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Anonymous
December 15, 2004 4:51:43 AM

Archived from groups: rec.audio.opinion,rec.audio.tech (More info?)

I am looking for an sound card that features dual DA converters in parallel.
Does anyone know of one?
tia
r


--
Nothing beats the bandwidth of a station wagon filled with DLT tapes.

More about : audio card

Anonymous
December 15, 2004 4:51:44 AM

Archived from groups: rec.audio.opinion,rec.audio.tech (More info?)

Robot said:

> I am looking for an sound card that features dual DA converters in parallel.

Do you need the second DAC to feed your positronic chip?
Anonymous
December 15, 2004 4:51:44 AM

Archived from groups: rec.audio.opinion,rec.audio.tech (More info?)

"R" <spmaway@ylhoo.com> wrote in message

> I am looking for an sound card that features dual DA converters in
parallel.
> Does anyone know of one?
> tia
> r

Turtle Beach.
Related resources
Anonymous
December 15, 2004 7:39:28 AM

Archived from groups: rec.audio.opinion,rec.audio.tech (More info?)

"Schizoid Man" <schiz@sf.com> wrote in news:cpo6ji$7jj$1
@geraldo.cc.utexas.edu:

>
> "R" <spmaway@ylhoo.com> wrote in message
>
>> I am looking for an sound card that features dual DA converters in
> parallel.
>> Does anyone know of one?
>> tia
>> r
>
> Turtle Beach.
>
>
>

It is not apparant that any of the models have two d-a converters running
in parallel.

r


--
Nothing beats the bandwidth of a station wagon filled with DLT tapes.
Anonymous
December 15, 2004 8:55:49 AM

Archived from groups: rec.audio.opinion,rec.audio.tech (More info?)

"R" <spmaway@ylhoo.com> wrote in message
news:Xns95BFCA0BD4122mc2500183316chgoill@10.232.1.1
> I am looking for an sound card that features dual DA converters in
> parallel. Does anyone know of one?

Please explain more precisely what you mean.
Anonymous
December 15, 2004 10:44:55 AM

Archived from groups: rec.audio.opinion,rec.audio.tech (More info?)

Turd-on-a-Rope shits on yet another misguided Kroopologist.

> > I am looking for an sound card that features dual DA converters in
> > parallel. Does anyone know of one?

> Please explain more precisely what you mean.

Robot means that the cat should have left you in the gutter with the other
trash. Or the homeless bum should have wiped you off his shoe. Or that you
should have been flushed with the other sewage.

It's perfectly clear to a Normal person.
Anonymous
December 15, 2004 1:05:06 PM

Archived from groups: rec.audio.opinion,rec.audio.tech (More info?)

"George M. Middius" <Spam-B-Gone@resistance.org> wrote in message
news:8q6vr0lfk6k2kljv9ie1e7u0hlomimddv7@4ax.com...
>
>
> Robot said:
>
>> I am looking for an sound card that features dual DA converters in
>> parallel.
>
> Do you need the second DAC to feed your positronic chip?

Maybe he is capturing imaginary music that will result
in complex numbers for the samples.
Anonymous
December 15, 2004 1:06:47 PM

Archived from groups: rec.audio.opinion,rec.audio.tech (More info?)

"R" wrote ...
>I am looking for an sound card that features dual DA
> converters in parallel. Does anyone know of one?

You wanna try that again?

Are you trying to solve some problem?
I've never seen a computer sound card that *didn't* have
at least two channels (i.e. "stereo")

Why do you think there is something "magic" about
"in parallel"?
Anonymous
December 15, 2004 4:17:07 PM

Archived from groups: rec.audio.opinion,rec.audio.tech (More info?)

Richard Crowley said:

> > Robot said:
> >
> >> I am looking for an sound card that features dual DA converters in
> >> parallel.
> >
> > Do you need the second DAC to feed your positronic chip?
>
> Maybe he is capturing imaginary music that will result
> in complex numbers for the samples.

I dunno. Andrews is a prole robot, not really equipped for metronic flights
of fancy. He chokes on irrational numbers.
Anonymous
December 15, 2004 8:57:12 PM

Archived from groups: rec.audio.opinion,rec.audio.tech (More info?)

On Wed, 15 Dec 2004 01:51:43 GMT, R <spmaway@ylhoo.com> wrote:

>I am looking for an sound card that features dual DA converters in parallel.
>Does anyone know of one?

You mean you want more than one stereo output? Sure. All the makers
of quality cards offer multichannel ones. M-Audio, Echo etc. etc.
Anonymous
December 15, 2004 9:34:11 PM

Archived from groups: rec.audio.opinion,rec.audio.tech (More info?)

"R" emitted :

>>> I am looking for an sound card that features dual DA converters in
>> parallel.
>>> Does anyone know of one?
>>> tia
>>> r
>>
>> Turtle Beach.
>>
>>
>>
>
>It is not apparant that any of the models have two d-a converters running
>in parallel.

If you have multiple output pairs, then you have dual or more DA
converters. If by 'in parallel' you mean synchronized to the same
clock, that should be as standard. My Echo Gina has the option to
disable "Synchronize wave devices", but that's really only for
developers.

I recall JJ bitching about some technicality relating to the
implementation of this, but I don't recall the specifics.


S i g n a l @ l i n e o n e . n e t
-----------------------------------
It's Grim up north..
Anonymous
December 16, 2004 1:45:20 AM

Archived from groups: rec.audio.opinion,rec.audio.tech (More info?)

"Arny Krueger" <arnyk@hotpop.com> wrote in news:QN2dnU2d2-ywhV3cRVn-
2A@comcast.com:

> "R" <spmaway@ylhoo.com> wrote in message
> news:Xns95BFCA0BD4122mc2500183316chgoill@10.232.1.1
>> I am looking for an sound card that features dual DA converters in
>> parallel. Does anyone know of one?
>
> Please explain more precisely what you mean.
>
>

Arny,

What I mean by parallel is that the data stream for one channel feeds 2 dacs
at once and the resultant output of the dacs are tied together. Many of the
high end CD players and D-A units use that circuit topology as it lowers the
distortion levels.

Adding a second D-A to a sound card in the field would be very difficult at
best.

r
Anonymous
December 16, 2004 2:06:54 AM

Archived from groups: rec.audio.opinion,rec.audio.tech (More info?)

"Richard Crowley" <rcrowley7@xprt.net> wrote in news:10s0v9njpd1hha7
@corp.supernews.com:

> "R" wrote ...
>>I am looking for an sound card that features dual DA
>> converters in parallel. Does anyone know of one?
>
> You wanna try that again?
>
> Are you trying to solve some problem?
> I've never seen a computer sound card that *didn't* have
> at least two channels (i.e. "stereo")
>
> Why do you think there is something "magic" about
> "in parallel"?
>
>

Not solving a problem per se, but I am trying to sort out which sound card I
might be happy with. Many of the common sound cards sound a bit harsh or
have some sort of "digital grunge" or both. The magic is that two DACs in
parallel lowers distortion. Proper chip decoupling lowers "digital grunge".

r
Anonymous
December 16, 2004 2:06:55 AM

Archived from groups: rec.audio.tech (More info?)

"Rich.Andrews" wrote ...
> Not solving a problem per se, but I am trying to sort out which
> sound card I might be happy with.

Go to Arny's website and look at his extensive measurements.
Then look at the Google Groups archives on the numerous discussion
of the merits of various soundcards in these newsgroups (and in
rec.audio.pro) I would not rely on rec.audio.opinion for real
technical discussions. They have a reputation for more philosophical
(or much stronger deprecatory adjectives) conversations. If you
just want to talk about sound cards, you should probably go over
there, but if you want to actually select one to buy and use, you are
better off in one of the more real-world newsgroups.

> Many of the common sound cards sound a bit harsh or have some
> sort of "digital grunge" or both.

You may be reading to much marketing babble. It seems likely that
even the cheapest $10 audio card features simultaneous clocking of
the samples on both input and output. Whether it subsequently uses
a single A/D or D/A converter or two in parallel or even sigma-
delta, or "1-bit", etc. etc. conversion is mostly immaterial.

Digital grunge in my experience is caused by cheap design (little
or no shielding, skimpy decoupling capacitors, etc.) and has nothing
to do with whether the design has single or dual DACs.

> The magic is that two DACs in parallel lowers distortion.

There is no technical basis for that statement, assuming some
minimal quality of the overall design. I challenge you to produce
the source of that factoid so that it can be properly evaluated in
context.

> Proper chip decoupling lowers "digital grunge".

Yes, but that has nothing to do with the number of DACs.
Anonymous
December 16, 2004 8:58:03 AM

Archived from groups: rec.audio.opinion,rec.audio.tech (More info?)

"Rich.Andrews" <spmaway@ylhoo.com> wrote in message
news:Xns95C0AA733F343bvzxrpl@10.232.1.1

> What I mean by parallel is that the data stream for one channel feeds
> 2 dacs at once and the resultant output of the dacs are tied
> together. Many of the high end CD players and D-A units use that
> circuit topology as it lowers the distortion levels.

Seems like a total waste, given the rediculously-low distortion levels
already obtained by more conventional means.

What a concept - use a better converter!

> Adding a second D-A to a sound card in the field would be very difficult
> at best.

Agreed.
Anonymous
December 16, 2004 9:01:08 AM

Archived from groups: rec.audio.opinion,rec.audio.tech (More info?)

"Rich.Andrews" <spmaway@ylhoo.com> wrote in message
news:Xns95C0AE1B2CE33bvzxrpl@10.232.1.1

> Not solving a problem per se, but I am trying to sort out which sound
> card I might be happy with. Many of the common sound cards sound a
> bit harsh or have some sort of "digital grunge" or both. The magic
> is that two DACs in parallel lowers distortion. Proper chip
> decoupling lowers "digital grunge".

Digital grunge is a marketing term with no real-world significance, in the
21st century world of top-quality converters.

Since I can run audio through a computer 20 times in a row without any
audible change as shown in the files from

http://www.pcabx.com/product/cardd_deluxe/index.htm

we have adequate proof that digital grunge is no longer a real-world
problem.
Anonymous
December 16, 2004 10:15:39 AM

Archived from groups: rec.audio.opinion,rec.audio.tech (More info?)

On Wed, 15 Dec 2004 22:45:20 GMT, "Rich.Andrews" <spmaway@ylhoo.com>
wrote:

>"Arny Krueger" <arnyk@hotpop.com> wrote in news:QN2dnU2d2-ywhV3cRVn-
>2A@comcast.com:
>
>> "R" <spmaway@ylhoo.com> wrote in message
>> news:Xns95BFCA0BD4122mc2500183316chgoill@10.232.1.1
>>> I am looking for an sound card that features dual DA converters in
>>> parallel. Does anyone know of one?
>>
>> Please explain more precisely what you mean.
>>
>>
>Arny,
>
>What I mean by parallel is that the data stream for one channel feeds 2 dacs
>at once and the resultant output of the dacs are tied together. Many of the
>high end CD players and D-A units use that circuit topology as it lowers the
>distortion levels.

You don't mean parallel, you mean a differential pair. Given that
distortion levels with conventional DACs can be 0.001% or less, do you
think this is important?

>Adding a second D-A to a sound card in the field would be very difficult at
>best.

Try a Lynx sound card, you will find no 'digital grunge' there. The
LynxOne is perhaps the best stereo sound card available, while the
LynxTwo-A will give you what you asked for - four channels with
balanced outputs.
--

Stewart Pinkerton | Music is Art - Audio is Engineering
Anonymous
December 16, 2004 10:20:41 AM

Archived from groups: rec.audio.opinion,rec.audio.tech (More info?)

Stewart Pinkerton <patent3@dircon.co.uk> wrote in
news:02d2s0l4rc62qqdancdr5o3jnurahbb0oe@4ax.com:

> On Wed, 15 Dec 2004 22:45:20 GMT, "Rich.Andrews" <spmaway@ylhoo.com>
> wrote:
>
>>"Arny Krueger" <arnyk@hotpop.com> wrote in news:QN2dnU2d2-ywhV3cRVn-
>>2A@comcast.com:
>>
>>> "R" <spmaway@ylhoo.com> wrote in message
>>> news:Xns95BFCA0BD4122mc2500183316chgoill@10.232.1.1
>>>> I am looking for an sound card that features dual DA converters in
>>>> parallel. Does anyone know of one?
>>>
>>> Please explain more precisely what you mean.
>>>
>>>
>>Arny,
>>
>>What I mean by parallel is that the data stream for one channel feeds 2
dacs
>>at once and the resultant output of the dacs are tied together. Many of
the
>>high end CD players and D-A units use that circuit topology as it lowers
the
>>distortion levels.
>
> You don't mean parallel, you mean a differential pair. Given that
> distortion levels with conventional DACs can be 0.001% or less, do you
> think this is important?
>


I don't think i mean a differential pair. Wuld not a differential pair be
2 dacs fed with the same source but one dac has it's invert pin asserted?

r


--
Nothing beats the bandwidth of a station wagon filled with DLT tapes.
Anonymous
December 16, 2004 10:51:10 AM

Archived from groups: rec.audio.opinion,rec.audio.tech (More info?)

"R" <spmaway@ylhoo.com> wrote in message
news:Xns95C1DAE5CF1Emc2500183316chgoill@10.232.1.1
> Stewart Pinkerton <patent3@dircon.co.uk> wrote in
> news:02d2s0l4rc62qqdancdr5o3jnurahbb0oe@4ax.com:
>
>> On Wed, 15 Dec 2004 22:45:20 GMT, "Rich.Andrews" <spmaway@ylhoo.com>
>> wrote:

>>> What I mean by parallel is that the data stream for one channel
>>> feeds 2 dacs at once and the resultant output of the dacs are tied
>>> together. Many of the high end CD players and D-A units use that
>>> circuit topology as it lowers the distortion levels.

Thinking back for a while, I remember the days when doubling up DAC chips
was sorta popular.

There was even a tweak that stacked two DAC chips on top of each other. This
kinda worked because many DAC chhips of the era had high impedance outputs,
so that their outputs were summed at the input to the following stage.

The net effect was that the output voltage was doubled (6 dB), while any
internally generated uncorrelated noise increased by only 3 dB.

However, the effects of running the sucessive stages at twice the signal
voltage were, err *unspecified*.

I never saw any technical tests that quantified the actual results. Of
course we had the usual "sounds better" garbage from the peanut gallery.

>> You don't mean parallel, you mean a differential pair. Given that
>> distortion levels with conventional DACs can be 0.001% or less, do
>> you think this is important?

Of course, the whole approach is rediculous and futile and turned out to
pretty much be yet another passing fancy of tweakdumb.

> I don't think i mean a differential pair. Wuld not a differential
> pair be 2 dacs fed with the same source but one dac has it's invert
> pin asserted?

This would be the better idea (in a land of futile non-thinking) because it
would eliminate such vanishing amounts of even order distortion as there
might be in the analog side of a quality DAC. Internally uncorrelated noise
would also be reduced, such as it might be.

Right now the better DAC chips are among the most precise of all audio
circuits. In production quantities I understand they run about $30. The real
challenge is finding op amps that will accurately deliver their performance
to the output terminals. Furthermore, if you look at the performance of
commodity DAC chips running about $1 or less, they are often as good or
better than the media being played.
Anonymous
December 16, 2004 2:21:10 PM

Archived from groups: rec.audio.opinion,rec.audio.tech (More info?)

In practice we take the one output and split it.

--

Jerry G.
======


"R" <spmaway@ylhoo.com> wrote in message
news:Xns95BFCA0BD4122mc2500183316chgoill@10.232.1.1...
I am looking for an sound card that features dual DA converters in parallel.
Does anyone know of one?
tia
r


--
Nothing beats the bandwidth of a station wagon filled with DLT tapes.
Anonymous
December 16, 2004 4:51:04 PM

Archived from groups: rec.audio.opinion,rec.audio.tech (More info?)

"Arny Krueger" <arnyk@hotpop.com> wrote in
news:CuCdnV8JE-YyGVzcRVn-og@comcast.com:

> "R" <spmaway@ylhoo.com> wrote in message
> news:Xns95C1DAE5CF1Emc2500183316chgoill@10.232.1.1
>> Stewart Pinkerton <patent3@dircon.co.uk> wrote in
>> news:02d2s0l4rc62qqdancdr5o3jnurahbb0oe@4ax.com:
>>
>>> On Wed, 15 Dec 2004 22:45:20 GMT, "Rich.Andrews" <spmaway@ylhoo.com>
>>> wrote:
>
>>>> What I mean by parallel is that the data stream for one channel
>>>> feeds 2 dacs at once and the resultant output of the dacs are tied
>>>> together. Many of the high end CD players and D-A units use that
>>>> circuit topology as it lowers the distortion levels.
>
> Thinking back for a while, I remember the days when doubling up DAC
> chips was sorta popular.
>

It is still done today by at least one manufacturer.

r


--
Nothing beats the bandwidth of a station wagon filled with DLT tapes.
Anonymous
December 16, 2004 4:51:05 PM

Archived from groups: rec.audio.opinion,rec.audio.tech (More info?)

"R" <spmaway@ylhoo.com> wrote in message
news:Xns95C14FDDCA902mc2500183316chgoill@10.232.1.1
> "Arny Krueger" <arnyk@hotpop.com> wrote in
> news:CuCdnV8JE-YyGVzcRVn-og@comcast.com:
>
>> "R" <spmaway@ylhoo.com> wrote in message
>> news:Xns95C1DAE5CF1Emc2500183316chgoill@10.232.1.1
>>> Stewart Pinkerton <patent3@dircon.co.uk> wrote in
>>> news:02d2s0l4rc62qqdancdr5o3jnurahbb0oe@4ax.com:
>>>
>>>> On Wed, 15 Dec 2004 22:45:20 GMT, "Rich.Andrews"
>>>> <spmaway@ylhoo.com> wrote:
>>
>>>>> What I mean by parallel is that the data stream for one channel
>>>>> feeds 2 dacs at once and the resultant output of the dacs are tied
>>>>> together. Many of the high end CD players and D-A units use that
>>>>> circuit topology as it lowers the distortion levels.
>>
>> Thinking back for a while, I remember the days when doubling up DAC
>> chips was sorta popular.
>>
>
> It is still done today by at least one manufacturer.

Down from how many at the peak of this particular weirdness?
Anonymous
December 16, 2004 8:50:08 PM

Archived from groups: rec.audio.opinion,rec.audio.tech (More info?)

On Thu, 16 Dec 2004 07:20:41 GMT, R <spmaway@ylhoo.com> wrote:

>Stewart Pinkerton <patent3@dircon.co.uk> wrote in
>news:02d2s0l4rc62qqdancdr5o3jnurahbb0oe@4ax.com:
>
>> On Wed, 15 Dec 2004 22:45:20 GMT, "Rich.Andrews" <spmaway@ylhoo.com>
>> wrote:
>>
>>>"Arny Krueger" <arnyk@hotpop.com> wrote in news:QN2dnU2d2-ywhV3cRVn-
>>>2A@comcast.com:
>>>
>>>> "R" <spmaway@ylhoo.com> wrote in message
>>>> news:Xns95BFCA0BD4122mc2500183316chgoill@10.232.1.1
>>>>> I am looking for an sound card that features dual DA converters in
>>>>> parallel. Does anyone know of one?
>>>>
>>>> Please explain more precisely what you mean.
>>>>
>>>>
>>>Arny,
>>>
>>>What I mean by parallel is that the data stream for one channel feeds 2 dacs
>>>at once and the resultant output of the dacs are tied together. Many of the
>>>high end CD players and D-A units use that circuit topology as it lowers the
>>>distortion levels.
>>
>> You don't mean parallel, you mean a differential pair. Given that
>> distortion levels with conventional DACs can be 0.001% or less, do you
>> think this is important?
>>
>I don't think i mean a differential pair. Wuld not a differential pair be
>2 dacs fed with the same source but one dac has it's invert pin asserted?

Essentially yes, and this is a classic method of averaging errors
between the two DACs.
--

Stewart Pinkerton | Music is Art - Audio is Engineering
Anonymous
December 16, 2004 8:50:09 PM

Archived from groups: rec.audio.opinion,rec.audio.tech (More info?)

"Stewart Pinkerton" <patent3@dircon.co.uk> wrote in message
news:bji3s053e67u14jv1e7s0070v9lccjqrc0@4ax.com
> On Thu, 16 Dec 2004 07:20:41 GMT, R <spmaway@ylhoo.com> wrote:
>
>> Stewart Pinkerton <patent3@dircon.co.uk> wrote in
>> news:02d2s0l4rc62qqdancdr5o3jnurahbb0oe@4ax.com:
>>
>>> On Wed, 15 Dec 2004 22:45:20 GMT, "Rich.Andrews" <spmaway@ylhoo.com>
>>> wrote:
>>>
>>>> "Arny Krueger" <arnyk@hotpop.com> wrote in
>>>> news:QN2dnU2d2-ywhV3cRVn- 2A@comcast.com:
>>>>
>>>>> "R" <spmaway@ylhoo.com> wrote in message
>>>>> news:Xns95BFCA0BD4122mc2500183316chgoill@10.232.1.1
>>>>>> I am looking for an sound card that features dual DA converters
>>>>>> in parallel. Does anyone know of one?
>>>>>
>>>>> Please explain more precisely what you mean.
>>>>>
>>>>>
>>>> Arny,
>>>>
>>>> What I mean by parallel is that the data stream for one channel
>>>> feeds 2 dacs at once and the resultant output of the dacs are
>>>> tied together. Many of the high end CD players and D-A units use
>>>> that circuit topology as it lowers the distortion levels.
>>>
>>> You don't mean parallel, you mean a differential pair. Given that
>>> distortion levels with conventional DACs can be 0.001% or less, do
>>> you think this is important?
>>>
>> I don't think i mean a differential pair. Wuld not a differential
>> pair be 2 dacs fed with the same source but one dac has it's invert
>> pin asserted?

Invert pins are kinda like historical artifacts on modern audio DACs.

This goes back to no later than the acension of sigma-delta DACs which
nearly totally dominate the present market for SOTA audio DACs.

> Essentially yes, and this is a classic method of averaging errors
> between the two DACs.

The real problem with this proposed solution is that modern DACs are highly
deterministic and tend to lack symetrical errors.

In fact, more benefit might come from operating the op amp buffers in a
balanced configuration. Many better audio DACs have + and - outputs.
Anonymous
December 16, 2004 9:14:23 PM

Archived from groups: rec.audio.opinion,rec.audio.tech (More info?)

"Arny Krueger" <arnyk@hotpop.com> wrote in message
news:CuCdnV8JE-YyGVzcRVn-og@comcast.com...
> "R" <spmaway@ylhoo.com> wrote in message
> news:Xns95C1DAE5CF1Emc2500183316chgoill@10.232.1.1
>> Stewart Pinkerton <patent3@dircon.co.uk> wrote in
>> news:02d2s0l4rc62qqdancdr5o3jnurahbb0oe@4ax.com:
>>
>>> On Wed, 15 Dec 2004 22:45:20 GMT, "Rich.Andrews" <spmaway@ylhoo.com>
>>> wrote:
>
>>>> What I mean by parallel is that the data stream for one channel
>>>> feeds 2 dacs at once and the resultant output of the dacs are tied
>>>> together. Many of the high end CD players and D-A units use that
>>>> circuit topology as it lowers the distortion levels.
>
> Thinking back for a while, I remember the days when doubling up DAC chips
> was sorta popular.
>
> There was even a tweak that stacked two DAC chips on top of each other.
> This kinda worked because many DAC chhips of the era had high impedance
> outputs, so that their outputs were summed at the input to the following
> stage.
>
> The net effect was that the output voltage was doubled (6 dB), while any
> internally generated uncorrelated noise increased by only 3 dB.

Care to explain this voltage doubling claim of yours Arny? I smell more
snake oil than hi-rez in PC/ABX.

ScottW
Anonymous
December 16, 2004 11:40:34 PM

Archived from groups: rec.audio.opinion,rec.audio.tech (More info?)

In rec.audio.tech R <spmaway@ylhoo.com> wrote:
> Stewart Pinkerton <patent3@dircon.co.uk> wrote in
> news:02d2s0l4rc62qqdancdr5o3jnurahbb0oe@4ax.com:
>
>> On Wed, 15 Dec 2004 22:45:20 GMT, "Rich.Andrews" <spmaway@ylhoo.com>
>> wrote:
>>
>>>"Arny Krueger" <arnyk@hotpop.com> wrote in news:QN2dnU2d2-ywhV3cRVn-
>>>2A@comcast.com:
>>>
>>>> "R" <spmaway@ylhoo.com> wrote in message
>>>> news:Xns95BFCA0BD4122mc2500183316chgoill@10.232.1.1
>>>>> I am looking for an sound card that features dual DA converters in
>>>>> parallel. Does anyone know of one?
>>>>
>>>> Please explain more precisely what you mean.
>>>>
>>>>
>>>Arny,
>>>
>>>What I mean by parallel is that the data stream for one channel feeds 2
> dacs
>>>at once and the resultant output of the dacs are tied together. Many of
> the
>>>high end CD players and D-A units use that circuit topology as it lowers
> the
>>>distortion levels.
>>
>> You don't mean parallel, you mean a differential pair. Given that
>> distortion levels with conventional DACs can be 0.001% or less, do you
>> think this is important?
>
> I don't think i mean a differential pair. Wuld not a differential pair be
> 2 dacs fed with the same source but one dac has it's invert pin asserted?

Can someone tell me what the difference is here?

Summing the output of two DACs should give "s1 + s2".
A differential pair, as I understand it, would be "s1 - (-s2)"

I don't see a difference. Am I missing something?
Anonymous
December 16, 2004 11:40:35 PM

Archived from groups: rec.audio.opinion,rec.audio.tech (More info?)

"Colin B." <cbigam@somewhereelse.nucleus.com> wrote in message
news:41c1f110@news.nucleus.com
> In rec.audio.tech R <spmaway@ylhoo.com> wrote:
>> Stewart Pinkerton <patent3@dircon.co.uk> wrote in
>> news:02d2s0l4rc62qqdancdr5o3jnurahbb0oe@4ax.com:
>>
>>> On Wed, 15 Dec 2004 22:45:20 GMT, "Rich.Andrews" <spmaway@ylhoo.com>
>>> wrote:
>>>
>>>> "Arny Krueger" <arnyk@hotpop.com> wrote in
>>>> news:QN2dnU2d2-ywhV3cRVn- 2A@comcast.com:
>>>>
>>>>> "R" <spmaway@ylhoo.com> wrote in message
>>>>> news:Xns95BFCA0BD4122mc2500183316chgoill@10.232.1.1
>>>>>> I am looking for an sound card that features dual DA converters
>>>>>> in parallel. Does anyone know of one?
>>>>>
>>>>> Please explain more precisely what you mean.
>>>>>
>>>>>
>>>> Arny,
>>>>
>>>> What I mean by parallel is that the data stream for one channel
>>>> feeds 2 dacs at once and the resultant output of the dacs are tied
>>>> together. Many of the high end CD players and D-A units use that
>>>> circuit topology as it lowers the distortion levels.
>>>
>>> You don't mean parallel, you mean a differential pair. Given that
>>> distortion levels with conventional DACs can be 0.001% or less, do
>>> you think this is important?
>>
>> I don't think i mean a differential pair. Wuld not a differential
>> pair be 2 dacs fed with the same source but one dac has it's invert
>> pin asserted?
>
> Can someone tell me what the difference is here?

> Summing the output of two DACs should give "s1 + s2".
> A differential pair, as I understand it, would be "s1 - (-s2)"

> I don't see a difference. Am I missing something?

Your algebra is correct for a simpler case, but it ignores the inversion of
the digital input, and the effect of that inversion on distortion.
Anonymous
December 17, 2004 12:13:05 AM

Archived from groups: rec.audio.opinion,rec.audio.tech (More info?)

On Wed, 15 Dec 2004 23:06:54 GMT, "Rich.Andrews" <spmaway@ylhoo.com>
wrote:

>Not solving a problem per se, but I am trying to sort out which sound card I
>might be happy with. Many of the common sound cards sound a bit harsh or
>have some sort of "digital grunge" or both. The magic is that two DACs in
>parallel lowers distortion. Proper chip decoupling lowers "digital grunge".

There are good and bad-sounding cards out there. But I wouldn't
worry too much about this particular bit of snake-oil. You've picked
it up from an audiophile review or advert? Come on over to the pro
audio world. You can still spend a lot of money if you insist, but
you'll get more for it than in the audiophile arena :-)
Anonymous
December 17, 2004 2:00:51 AM

Archived from groups: rec.audio.opinion,rec.audio.tech (More info?)

"Arny Krueger" <arnyk@hotpop.com> wrote in news:jNSdnfAzYIQMIVzcRVn-
pA@comcast.com:

> "R" <spmaway@ylhoo.com> wrote in message
> news:Xns95C14FDDCA902mc2500183316chgoill@10.232.1.1
>> "Arny Krueger" <arnyk@hotpop.com> wrote in
>> news:CuCdnV8JE-YyGVzcRVn-og@comcast.com:
>>
>>> "R" <spmaway@ylhoo.com> wrote in message
>>> news:Xns95C1DAE5CF1Emc2500183316chgoill@10.232.1.1
>>>> Stewart Pinkerton <patent3@dircon.co.uk> wrote in
>>>> news:02d2s0l4rc62qqdancdr5o3jnurahbb0oe@4ax.com:
>>>>
>>>>> On Wed, 15 Dec 2004 22:45:20 GMT, "Rich.Andrews"
>>>>> <spmaway@ylhoo.com> wrote:
>>>
>>>>>> What I mean by parallel is that the data stream for one channel
>>>>>> feeds 2 dacs at once and the resultant output of the dacs are tied
>>>>>> together. Many of the high end CD players and D-A units use that
>>>>>> circuit topology as it lowers the distortion levels.
>>>
>>> Thinking back for a while, I remember the days when doubling up DAC
>>> chips was sorta popular.
>>>
>>
>> It is still done today by at least one manufacturer.
>
> Down from how many at the peak of this particular weirdness?
>
>
>

I don't believe the count is relevant. The point is that putting two dacs
in parallel lowers distortion and I feel that if I am going to spend some
money, I might as well spend a bit more and get the best.

r
Anonymous
December 17, 2004 2:00:52 AM

Archived from groups: rec.audio.opinion,rec.audio.tech (More info?)

"Rich.Andrews" <spmaway@ylhoo.com> wrote in message
news:Xns95C1AD140A87Bbvzxrpl@10.232.1.1

>
> I don't believe the count is relevant. The point is that putting two
> dacs in parallel lowers distortion and I feel that if I am going to
> spend some money, I might as well spend a bit more and get the best.

In audio interfaces, AFAIK "The Best" is the LynxTWO.
Anonymous
December 17, 2004 2:09:32 AM

Archived from groups: rec.audio.opinion,rec.audio.tech (More info?)

"Colin B." <cbigam@somewhereelse.nucleus.com> wrote in
news:41c1f110@news.nucleus.com:

> In rec.audio.tech R <spmaway@ylhoo.com> wrote:
>> Stewart Pinkerton <patent3@dircon.co.uk> wrote in
>> news:02d2s0l4rc62qqdancdr5o3jnurahbb0oe@4ax.com:
>>
>>> On Wed, 15 Dec 2004 22:45:20 GMT, "Rich.Andrews" <spmaway@ylhoo.com>
>>> wrote:
>>>
>>>>"Arny Krueger" <arnyk@hotpop.com> wrote in news:QN2dnU2d2-ywhV3cRVn-
>>>>2A@comcast.com:
>>>>
>>>>> "R" <spmaway@ylhoo.com> wrote in message
>>>>> news:Xns95BFCA0BD4122mc2500183316chgoill@10.232.1.1
>>>>>> I am looking for an sound card that features dual DA converters in
>>>>>> parallel. Does anyone know of one?
>>>>>
>>>>> Please explain more precisely what you mean.
>>>>>
>>>>>
>>>>Arny,
>>>>
>>>>What I mean by parallel is that the data stream for one channel feeds
>>>>2
>> dacs
>>>>at once and the resultant output of the dacs are tied together. Many
>>>>of
>> the
>>>>high end CD players and D-A units use that circuit topology as it
>>>>lowers
>> the
>>>>distortion levels.
>>>
>>> You don't mean parallel, you mean a differential pair. Given that
>>> distortion levels with conventional DACs can be 0.001% or less, do you
>>> think this is important?
>>
>> I don't think i mean a differential pair. Wuld not a differential pair
>> be 2 dacs fed with the same source but one dac has it's invert pin
>> asserted?
>
> Can someone tell me what the difference is here?
>
> Summing the output of two DACs should give "s1 + s2".
> A differential pair, as I understand it, would be "s1 - (-s2)"
>
> I don't see a difference. Am I missing something?
>

As I see it, in a balanced audio setup the positive dac output would be
the plus side and the inverted dac output would be the negative side. The
common mode noise would be diminished in such a configuration.

In the configuration I am referring to, it would e a simple single ended
unbalanced output but with 2 dacs sharing inputs and outputs.


r
Anonymous
December 17, 2004 2:12:20 AM

Archived from groups: rec.audio.opinion,rec.audio.tech (More info?)

Laurence Payne <l@laurenceDELETEpayne.freeserve.co.uk> wrote in
news:18u3s05ervp0kh883itsinog7i9go40le8@4ax.com:

> On Wed, 15 Dec 2004 23:06:54 GMT, "Rich.Andrews" <spmaway@ylhoo.com>
> wrote:
>
>>Not solving a problem per se, but I am trying to sort out which sound
>>card I might be happy with. Many of the common sound cards sound a bit
>>harsh or have some sort of "digital grunge" or both. The magic is that
>>two DACs in parallel lowers distortion. Proper chip decoupling lowers
>>"digital grunge".
>
> There are good and bad-sounding cards out there. But I wouldn't
> worry too much about this particular bit of snake-oil. You've picked
> it up from an audiophile review or advert? Come on over to the pro
> audio world. You can still spend a lot of money if you insist, but
> you'll get more for it than in the audiophile arena :-)
>

I have actually picked it up from reviewing schematics of CD players and
stand alone DACs that I own or have considered owning.

r
Anonymous
December 17, 2004 3:34:22 AM

Archived from groups: rec.audio.opinion,rec.audio.tech (More info?)

"Stewart Pinkerton" <patent3@dircon.co.uk> wrote in message
news:bji3s053e67u14jv1e7s0070v9lccjqrc0@4ax.com...
> On Thu, 16 Dec 2004 07:20:41 GMT, R <spmaway@ylhoo.com> wrote:
>
> >Stewart Pinkerton <patent3@dircon.co.uk> wrote in
> >news:02d2s0l4rc62qqdancdr5o3jnurahbb0oe@4ax.com:
> >
> >> On Wed, 15 Dec 2004 22:45:20 GMT, "Rich.Andrews"
<spmaway@ylhoo.com>
> >> wrote:
> >>
> >>>"Arny Krueger" <arnyk@hotpop.com> wrote in
news:QN2dnU2d2-ywhV3cRVn-
> >>>2A@comcast.com:
> >>>
> >>>> "R" <spmaway@ylhoo.com> wrote in message
> >>>> news:Xns95BFCA0BD4122mc2500183316chgoill@10.232.1.1
> >>>>> I am looking for an sound card that features dual DA
converters in
> >>>>> parallel. Does anyone know of one?
> >>>>
> >>>> Please explain more precisely what you mean.
> >>>>
> >>>>
> >>>Arny,
> >>>
> >>>What I mean by parallel is that the data stream for one channel
feeds 2 dacs
> >>>at once and the resultant output of the dacs are tied together.
Many of the
> >>>high end CD players and D-A units use that circuit topology as it
lowers the
> >>>distortion levels.
> >>
> >> You don't mean parallel, you mean a differential pair. Given that
> >> distortion levels with conventional DACs can be 0.001% or less,
do you
> >> think this is important?
> >>
> >I don't think i mean a differential pair. Wuld not a differential
pair be
> >2 dacs fed with the same source but one dac has it's invert pin
asserted?
>
> Essentially yes, and this is a classic method of averaging errors
> between the two DACs.

If the 2 DACs come from the entire universe of DACs then this will
probably work. But if they come from the same production run or, God
forbid, from the same wafer, the chances are excellent that both DACs
will have errors in exactly the same place--in the same direction.
You could get no benefit from averaging.

Norm Strong
Anonymous
December 17, 2004 3:50:20 AM

Archived from groups: rec.audio.opinion,rec.audio.tech (More info?)

"Arny Krueger" <arnyk@hotpop.com> wrote in news:qZ-dnTNPju7CgF_cRVn-
og@comcast.com:

> "Rich.Andrews" <spmaway@ylhoo.com> wrote in message
> news:Xns95C1AD140A87Bbvzxrpl@10.232.1.1
>
>>
>> I don't believe the count is relevant. The point is that putting two
>> dacs in parallel lowers distortion and I feel that if I am going to
>> spend some money, I might as well spend a bit more and get the best.
>
> In audio interfaces, AFAIK "The Best" is the LynxTWO.
>
>
>

An input impedance of 24 ohms balanced and 12 ohms unbalanced? Isn't that
a bit low?

r


--
Nothing beats the bandwidth of a station wagon filled with DLT tapes.
Anonymous
December 17, 2004 4:20:48 AM

Archived from groups: rec.audio.opinion,rec.audio.tech (More info?)

R wrote:

> "Arny Krueger" <arnyk@hotpop.com> wrote in news:qZ-dnTNPju7CgF_cRVn-
> og@comcast.com:
>
> > "Rich.Andrews" <spmaway@ylhoo.com> wrote in message
> > news:Xns95C1AD140A87Bbvzxrpl@10.232.1.1
> >
> >>
> >> I don't believe the count is relevant. The point is that putting two
> >> dacs in parallel lowers distortion and I feel that if I am going to
> >> spend some money, I might as well spend a bit more and get the best.
> >
> > In audio interfaces, AFAIK "The Best" is the LynxTWO.
> >
> >
> >
>
> An input impedance of 24 ohms balanced and 12 ohms unbalanced? Isn't that
> a bit low?
>

Apparently you can't read a spec sheet.

Input Impedance Balanced mode: 24 kW , Unbalanced mode: 12 kW ( the ohms
symbol appears as W in plain text btw ).

http://www.lynxstudio.com/lynxtwospecs.html

IIRC - most modern converters work differentially internally anyway. The
inputs and outputs on the converters I'm currently using are differential and
most others I've looked at are too. Those that are 'single ended' usually have
an internal inverting stage that converts them to internally differential.

You're worrying about non-issues.


Graham
Anonymous
December 17, 2004 5:10:51 AM

Archived from groups: rec.audio.opinion,rec.audio.tech (More info?)

On Thu, 16 Dec 2004 23:12:20 GMT, "Rich.Andrews" <spmaway@ylhoo.com>
wrote:

>> There are good and bad-sounding cards out there. But I wouldn't
>> worry too much about this particular bit of snake-oil. You've picked
>> it up from an audiophile review or advert? Come on over to the pro
>> audio world. You can still spend a lot of money if you insist, but
>> you'll get more for it than in the audiophile arena :-)
>>
>
>I have actually picked it up from reviewing schematics of CD players and
>stand alone DACs that I own or have considered owning.

Yeah. But is it a marketing ploy, or is it actually solving a real
problem?
Anonymous
December 17, 2004 5:59:01 AM

Archived from groups: rec.audio.opinion,rec.audio.tech (More info?)

ScottW wrote:

> "Arny Krueger" <arnyk@hotpop.com> wrote in message
> news:CuCdnV8JE-YyGVzcRVn-og@comcast.com...
> > "R" <spmaway@ylhoo.com> wrote in message
> > news:Xns95C1DAE5CF1Emc2500183316chgoill@10.232.1.1
> >> Stewart Pinkerton <patent3@dircon.co.uk> wrote in
> >> news:02d2s0l4rc62qqdancdr5o3jnurahbb0oe@4ax.com:
> >>
> >>> On Wed, 15 Dec 2004 22:45:20 GMT, "Rich.Andrews" <spmaway@ylhoo.com>
> >>> wrote:
> >
> >>>> What I mean by parallel is that the data stream for one channel
> >>>> feeds 2 dacs at once and the resultant output of the dacs are tied
> >>>> together. Many of the high end CD players and D-A units use that
> >>>> circuit topology as it lowers the distortion levels.
> >
> > Thinking back for a while, I remember the days when doubling up DAC chips
> > was sorta popular.
> >
> > There was even a tweak that stacked two DAC chips on top of each other.
> > This kinda worked because many DAC chhips of the era had high impedance
> > outputs, so that their outputs were summed at the input to the following
> > stage.
> >
> > The net effect was that the output voltage was doubled (6 dB), while any
> > internally generated uncorrelated noise increased by only 3 dB.
>
> Care to explain this voltage doubling claim of yours Arny? I smell more
> snake oil than hi-rez in PC/ABX.

Just stepping in here.....

Those old converter chips were current output. 2 chips = twice the current =
double the voltage for the same output stage following it.

The noise only rises by 3dB since noise isn't a coherent signal ( it's random
). Each converter produces its own random noise so there is an overall
improvement in S/N of 3dB. You need to understand how signals sum to properly
follow this bit.

Standard output voltage can be obtained by halving the feedback resistor value
in the op-amp following the DAC. This helps reduce noise a tiny bit too since
lower value resistors have less thermal noise.

Graham
Anonymous
December 17, 2004 6:01:16 AM

Archived from groups: rec.audio.opinion,rec.audio.tech (More info?)

Arny Krueger wrote:

> "Stewart Pinkerton" <patent3@dircon.co.uk> wrote in message
> news:bji3s053e67u14jv1e7s0070v9lccjqrc0@4ax.com
> > On Thu, 16 Dec 2004 07:20:41 GMT, R <spmaway@ylhoo.com> wrote:
> >
> >> Stewart Pinkerton <patent3@dircon.co.uk> wrote in
> >> news:02d2s0l4rc62qqdancdr5o3jnurahbb0oe@4ax.com:
> >>
> >>> On Wed, 15 Dec 2004 22:45:20 GMT, "Rich.Andrews" <spmaway@ylhoo.com>
> >>> wrote:
> >>>
> >>>> "Arny Krueger" <arnyk@hotpop.com> wrote in
> >>>> news:QN2dnU2d2-ywhV3cRVn- 2A@comcast.com:
> >>>>
> >>>>> "R" <spmaway@ylhoo.com> wrote in message
> >>>>> news:Xns95BFCA0BD4122mc2500183316chgoill@10.232.1.1
> >>>>>> I am looking for an sound card that features dual DA converters
> >>>>>> in parallel. Does anyone know of one?
> >>>>>
> >>>>> Please explain more precisely what you mean.
> >>>>>
> >>>>>
> >>>> Arny,
> >>>>
> >>>> What I mean by parallel is that the data stream for one channel
> >>>> feeds 2 dacs at once and the resultant output of the dacs are
> >>>> tied together. Many of the high end CD players and D-A units use
> >>>> that circuit topology as it lowers the distortion levels.
> >>>
> >>> You don't mean parallel, you mean a differential pair. Given that
> >>> distortion levels with conventional DACs can be 0.001% or less, do
> >>> you think this is important?
> >>>
> >> I don't think i mean a differential pair. Wuld not a differential
> >> pair be 2 dacs fed with the same source but one dac has it's invert
> >> pin asserted?
>
> Invert pins are kinda like historical artifacts on modern audio DACs.
>
> This goes back to no later than the acension of sigma-delta DACs which
> nearly totally dominate the present market for SOTA audio DACs.
>
> > Essentially yes, and this is a classic method of averaging errors
> > between the two DACs.
>
> The real problem with this proposed solution is that modern DACs are highly
> deterministic and tend to lack symetrical errors.
>
> In fact, more benefit might come from operating the op amp buffers in a
> balanced configuration. Many better audio DACs have + and - outputs.

This is the topology I use. I can't recall seeing a recent serious DAC data
sheet that doesn't recommend this method.

Graham
Anonymous
December 17, 2004 6:02:50 AM

Archived from groups: rec.audio.opinion,rec.audio.tech (More info?)

normanstrong wrote:

> "Stewart Pinkerton" <patent3@dircon.co.uk> wrote in message
> news:bji3s053e67u14jv1e7s0070v9lccjqrc0@4ax.com...
> > On Thu, 16 Dec 2004 07:20:41 GMT, R <spmaway@ylhoo.com> wrote:
> >
> > >Stewart Pinkerton <patent3@dircon.co.uk> wrote in
> > >news:02d2s0l4rc62qqdancdr5o3jnurahbb0oe@4ax.com:
> > >
> > >> On Wed, 15 Dec 2004 22:45:20 GMT, "Rich.Andrews"
> <spmaway@ylhoo.com>
> > >> wrote:
> > >>
> > >>>"Arny Krueger" <arnyk@hotpop.com> wrote in
> news:QN2dnU2d2-ywhV3cRVn-
> > >>>2A@comcast.com:
> > >>>
> > >>>> "R" <spmaway@ylhoo.com> wrote in message
> > >>>> news:Xns95BFCA0BD4122mc2500183316chgoill@10.232.1.1
> > >>>>> I am looking for an sound card that features dual DA
> converters in
> > >>>>> parallel. Does anyone know of one?
> > >>>>
> > >>>> Please explain more precisely what you mean.
> > >>>>
> > >>>>
> > >>>Arny,
> > >>>
> > >>>What I mean by parallel is that the data stream for one channel
> feeds 2 dacs
> > >>>at once and the resultant output of the dacs are tied together.
> Many of the
> > >>>high end CD players and D-A units use that circuit topology as it
> lowers the
> > >>>distortion levels.
> > >>
> > >> You don't mean parallel, you mean a differential pair. Given that
> > >> distortion levels with conventional DACs can be 0.001% or less,
> do you
> > >> think this is important?
> > >>
> > >I don't think i mean a differential pair. Wuld not a differential
> pair be
> > >2 dacs fed with the same source but one dac has it's invert pin
> asserted?
> >
> > Essentially yes, and this is a classic method of averaging errors
> > between the two DACs.
>
> If the 2 DACs come from the entire universe of DACs then this will
> probably work. But if they come from the same production run or, God
> forbid, from the same wafer, the chances are excellent that both DACs
> will have errors in exactly the same place--in the same direction.
> You could get no benefit from averaging.

Not so. The differences are likely to be 'process related'. No 2 chips
from the same wafer are identical. The method is ( was ) valid.

Graham
Anonymous
December 17, 2004 6:02:51 AM

Archived from groups: rec.audio.opinion,rec.audio.tech (More info?)

"Pooh Bear" wrote ...
> normanstrong wrote:
>> If the 2 DACs come from the entire universe of DACs then this will
>> probably work. But if they come from the same production run or, God
>> forbid, from the same wafer, the chances are excellent that both DACs
>> will have errors in exactly the same place--in the same direction.
>> You could get no benefit from averaging.
>
> Not so. The differences are likely to be 'process related'. No 2 chips
> from the same wafer are identical. The method is ( was ) valid.

We fabricate several million die per year next door and I'd
have to agree with Mr. Bear. There is sufficient variation
over even a single wafer to use dual DACs to "swamp out"
any errors.
Anonymous
December 17, 2004 6:04:23 AM

Archived from groups: rec.audio.opinion,rec.audio.tech (More info?)

Pooh Bear <rabbitsfriendsandrelations@hotmail.com> wrote in
news:41C23470.999D67F7@hotmail.com:

> R wrote:
>
>> "Arny Krueger" <arnyk@hotpop.com> wrote in news:qZ-dnTNPju7CgF_cRVn-
>> og@comcast.com:
>>
>> > "Rich.Andrews" <spmaway@ylhoo.com> wrote in message
>> > news:Xns95C1AD140A87Bbvzxrpl@10.232.1.1
>> >
>> >>
>> >> I don't believe the count is relevant. The point is that putting
>> >> two dacs in parallel lowers distortion and I feel that if I am going
>> >> to spend some money, I might as well spend a bit more and get the
>> >> best.
>> >
>> > In audio interfaces, AFAIK "The Best" is the LynxTWO.
>> >
>> >
>> >
>>
>> An input impedance of 24 ohms balanced and 12 ohms unbalanced? Isn't
>> that a bit low?
>>
>
> Apparently you can't read a spec sheet.
>
> Input Impedance Balanced mode: 24 kW , Unbalanced mode: 12 kW ( the
> ohms symbol appears as W in plain text btw ).
>
> http://www.lynxstudio.com/lynxtwospecs.html
>
> IIRC - most modern converters work differentially internally anyway. The
> inputs and outputs on the converters I'm currently using are
> differential and most others I've looked at are too. Those that are
> 'single ended' usually have an internal inverting stage that converts
> them to internally differential.
>
> You're worrying about non-issues.
>
>
> Graham
>
>

http://lynxstudio.com/reviews/LynxTWOBrochureLoRes.pdf

Clearly says "Unbalanced Mode: 12 <greek omega>"

That means 12 ohms, not 12k ohms.

What were you saying about reading a spec sheet?

r
Anonymous
December 17, 2004 6:07:37 AM

Archived from groups: rec.audio.opinion,rec.audio.tech (More info?)

"Colin B." wrote:

> In rec.audio.tech R <spmaway@ylhoo.com> wrote:
> > Stewart Pinkerton <patent3@dircon.co.uk> wrote in
> > news:02d2s0l4rc62qqdancdr5o3jnurahbb0oe@4ax.com:
> >
> >> On Wed, 15 Dec 2004 22:45:20 GMT, "Rich.Andrews" <spmaway@ylhoo.com>
> >> wrote:
> >>
> >>>"Arny Krueger" <arnyk@hotpop.com> wrote in news:QN2dnU2d2-ywhV3cRVn-
> >>>2A@comcast.com:
> >>>
> >>>> "R" <spmaway@ylhoo.com> wrote in message
> >>>> news:Xns95BFCA0BD4122mc2500183316chgoill@10.232.1.1
> >>>>> I am looking for an sound card that features dual DA converters in
> >>>>> parallel. Does anyone know of one?
> >>>>
> >>>> Please explain more precisely what you mean.
> >>>>
> >>>>
> >>>Arny,
> >>>
> >>>What I mean by parallel is that the data stream for one channel feeds 2
> > dacs
> >>>at once and the resultant output of the dacs are tied together. Many of
> > the
> >>>high end CD players and D-A units use that circuit topology as it lowers
> > the
> >>>distortion levels.
> >>
> >> You don't mean parallel, you mean a differential pair. Given that
> >> distortion levels with conventional DACs can be 0.001% or less, do you
> >> think this is important?
> >
> > I don't think i mean a differential pair. Wuld not a differential pair be
> > 2 dacs fed with the same source but one dac has it's invert pin asserted?
>
> Can someone tell me what the difference is here?
>
> Summing the output of two DACs should give "s1 + s2".
> A differential pair, as I understand it, would be "s1 - (-s2)"
>
> I don't see a difference. Am I missing something?

Yup ! ;-)

The principle assumed a conversion error that had a common factor for a given
digital code input. Typically R-2R ladder types.

The output = ( sig1 + error ) - ( -sig2 + error )

= sig 1 + sig2 ( and no error ) = 2 x sig1

Modern converters aren't like this.

Graham
Anonymous
December 17, 2004 6:11:47 AM

Archived from groups: rec.audio.opinion,rec.audio.tech (More info?)

"Rich.Andrews" wrote:

> "Richard Crowley" <rcrowley7@xprt.net> wrote in news:10s0v9njpd1hha7
> @corp.supernews.com:
>
> > "R" wrote ...
> >>I am looking for an sound card that features dual DA
> >> converters in parallel. Does anyone know of one?
> >
> > You wanna try that again?
> >
> > Are you trying to solve some problem?
> > I've never seen a computer sound card that *didn't* have
> > at least two channels (i.e. "stereo")
> >
> > Why do you think there is something "magic" about
> > "in parallel"?
> >
> >
>
> Not solving a problem per se, but I am trying to sort out which sound card I
> might be happy with. Many of the common sound cards sound a bit harsh or
> have some sort of "digital grunge" or both. The magic is that two DACs in
> parallel lowers distortion.

Not any more. In fact modern DACs have voltage outputs so you can't parallel
them like 12+ yr old current output DACs.


> Proper chip decoupling lowers "digital grunge".

Actually - proper grounding design is the answer to that problem. I design
pro-audio DSP stuff so I know.


Graham
Anonymous
December 17, 2004 6:22:21 AM

Archived from groups: rec.audio.opinion,rec.audio.tech (More info?)

Laurence Payne <l@laurenceDELETEpayne.freeserve.co.uk> wrote in
news:c0g4s0h2tpmp46so68egcqk0kfjbvqp8eh@4ax.com:

> On Thu, 16 Dec 2004 23:12:20 GMT, "Rich.Andrews" <spmaway@ylhoo.com>
> wrote:
>
>>> There are good and bad-sounding cards out there. But I wouldn't
>>> worry too much about this particular bit of snake-oil. You've picked
>>> it up from an audiophile review or advert? Come on over to the pro
>>> audio world. You can still spend a lot of money if you insist, but
>>> you'll get more for it than in the audiophile arena :-)
>>>
>>
>>I have actually picked it up from reviewing schematics of CD players and
>>stand alone DACs that I own or have considered owning.
>
> Yeah. But is it a marketing ploy, or is it actually solving a real
> problem?
>

As far as I am concerned it does make a difference. Don't believe me?
Fine don't. I really don't care. Either the card I am looking for exists
or it doesn't. Unfortunately it appears it does not. So I am going to
have to start from scratch pouring over spec sheets.

The pro cards have more capabilities than what I would ever need but I fear
that they pro cards are geared toward 600 ohm balanced and I need high
impedance (~50k ohm) unbalanced as well as 600 ohms balanced.

r
Anonymous
December 17, 2004 6:23:44 AM

Archived from groups: rec.audio.opinion,rec.audio.tech (More info?)

"Rich.Andrews" wrote:

> Pooh Bear <rabbitsfriendsandrelations@hotmail.com> wrote in
> news:41C23470.999D67F7@hotmail.com:
>
> > R wrote:
> >
> >> "Arny Krueger" <arnyk@hotpop.com> wrote in news:qZ-dnTNPju7CgF_cRVn-
> >> og@comcast.com:
> >>
> >> > "Rich.Andrews" <spmaway@ylhoo.com> wrote in message
> >> > news:Xns95C1AD140A87Bbvzxrpl@10.232.1.1
> >> >
> >> >>
> >> >> I don't believe the count is relevant. The point is that putting
> >> >> two dacs in parallel lowers distortion and I feel that if I am going
> >> >> to spend some money, I might as well spend a bit more and get the
> >> >> best.
> >> >
> >> > In audio interfaces, AFAIK "The Best" is the LynxTWO.
> >> >
> >> >
> >> >
> >>
> >> An input impedance of 24 ohms balanced and 12 ohms unbalanced? Isn't
> >> that a bit low?
> >>
> >
> > Apparently you can't read a spec sheet.
> >
> > Input Impedance Balanced mode: 24 kW , Unbalanced mode: 12 kW ( the
> > ohms symbol appears as W in plain text btw ).
> >
> > http://www.lynxstudio.com/lynxtwospecs.html
> >
> > IIRC - most modern converters work differentially internally anyway. The
> > inputs and outputs on the converters I'm currently using are
> > differential and most others I've looked at are too. Those that are
> > 'single ended' usually have an internal inverting stage that converts
> > them to internally differential.
> >
> > You're worrying about non-issues.
> >
> >
> > Graham
> >
> >
>
> http://lynxstudio.com/reviews/LynxTWOBrochureLoRes.pdf
>
> Clearly says "Unbalanced Mode: 12 <greek omega>"
>
> That means 12 ohms, not 12k ohms.
>
> What were you saying about reading a spec sheet?

That's a 'printing error' obviously. Input impedances are clearly going to be
kilohms. They ought to get someone to proof read better.

Check my link.

Graham
Anonymous
December 17, 2004 6:31:59 AM

Archived from groups: rec.audio.opinion,rec.audio.tech (More info?)

"Rich.Andrews" wrote:

> Laurence Payne <l@laurenceDELETEpayne.freeserve.co.uk> wrote in
> news:18u3s05ervp0kh883itsinog7i9go40le8@4ax.com:
>
> > On Wed, 15 Dec 2004 23:06:54 GMT, "Rich.Andrews" <spmaway@ylhoo.com>
> > wrote:
> >
> >>Not solving a problem per se, but I am trying to sort out which sound
> >>card I might be happy with. Many of the common sound cards sound a bit
> >>harsh or have some sort of "digital grunge" or both. The magic is that
> >>two DACs in parallel lowers distortion. Proper chip decoupling lowers
> >>"digital grunge".
> >
> > There are good and bad-sounding cards out there. But I wouldn't
> > worry too much about this particular bit of snake-oil. You've picked
> > it up from an audiophile review or advert? Come on over to the pro
> > audio world. You can still spend a lot of money if you insist, but
> > you'll get more for it than in the audiophile arena :-)
> >
>
> I have actually picked it up from reviewing schematics of CD players and
> stand alone DACs that I own or have considered owning.

I suggest you look at DAC manufacturers data for modern parts.

Here's one from AKM for example. Note the differential output.

http://www.asahi-kasei.co.jp/akm/en/product/ak4395/ak43...

Check out the recommended grounding on page 22 and the external differential
Low Pass Filters on page 23 of the following pdf.

http://www.asahi-kasei.co.jp/akm/en/product/ak4395/ek43...


Graham
Anonymous
December 17, 2004 6:37:59 AM

Archived from groups: rec.audio.opinion,rec.audio.tech (More info?)

"Rich.Andrews" wrote:

> Laurence Payne <l@laurenceDELETEpayne.freeserve.co.uk> wrote in
> news:c0g4s0h2tpmp46so68egcqk0kfjbvqp8eh@4ax.com:
>
> > On Thu, 16 Dec 2004 23:12:20 GMT, "Rich.Andrews" <spmaway@ylhoo.com>
> > wrote:
> >
> >>> There are good and bad-sounding cards out there. But I wouldn't
> >>> worry too much about this particular bit of snake-oil. You've picked
> >>> it up from an audiophile review or advert? Come on over to the pro
> >>> audio world. You can still spend a lot of money if you insist, but
> >>> you'll get more for it than in the audiophile arena :-)
> >>>
> >>
> >>I have actually picked it up from reviewing schematics of CD players and
> >>stand alone DACs that I own or have considered owning.
> >
> > Yeah. But is it a marketing ploy, or is it actually solving a real
> > problem?
> >
>
> As far as I am concerned it does make a difference. Don't believe me?
> Fine don't. I really don't care. Either the card I am looking for exists
> or it doesn't. Unfortunately it appears it does not. So I am going to
> have to start from scratch pouring over spec sheets.

Look. Just about any modern sound card will use a differential output DAC.

The sound quality isues will lie elsewhere. Like good grounding design and the
use of decent pro-audio grade op-amps for the ins and outs.

The quality of the *connectors* is actually very important too. Mini jacks
don't cut it !


> The pro cards have more capabilities than what I would ever need but I fear
> that they pro cards are geared toward 600 ohm balanced and I need high
> impedance (~50k ohm) unbalanced as well as 600 ohms balanced.

Apparently you also don't realise that so-called '600 ohm' ( a misnomer btw )
circuits work just fine with Hi-Z too.

If you have Hi-Z gear ( with its lower performance ) why are you agonising over
DACs ?


Graham
Anonymous
December 17, 2004 9:14:32 AM

Archived from groups: rec.audio.opinion,rec.audio.tech (More info?)

Richard Crowley wrote:

> "Pooh Bear" wrote ...
> > normanstrong wrote:
> >> If the 2 DACs come from the entire universe of DACs then this will
> >> probably work. But if they come from the same production run or, God
> >> forbid, from the same wafer, the chances are excellent that both DACs
> >> will have errors in exactly the same place--in the same direction.
> >> You could get no benefit from averaging.
> >
> > Not so. The differences are likely to be 'process related'. No 2 chips
> > from the same wafer are identical. The method is ( was ) valid.
>
> We fabricate several million die per year next door and I'd
> have to agree with Mr. Bear. There is sufficient variation
> over even a single wafer to use dual DACs to "swamp out"
> any errors.

Thank you for validating my comment from your experience.

It is perhaps not widely realised that making semis is somewhat more like
baking a cake than some would like to admit.

They don't call them 'ovens' for nothing ! ;-)


Graham
Anonymous
December 17, 2004 10:06:16 AM

Archived from groups: rec.audio.opinion,rec.audio.tech (More info?)

Pooh Bear <rabbitsfriendsandrelations@hotmail.com> wrote in
news:41C25497.E5BEBF2@hotmail.com:

> "Rich.Andrews" wrote:
>
>> Laurence Payne <l@laurenceDELETEpayne.freeserve.co.uk> wrote in
>> news:c0g4s0h2tpmp46so68egcqk0kfjbvqp8eh@4ax.com:
>>
>> > On Thu, 16 Dec 2004 23:12:20 GMT, "Rich.Andrews" <spmaway@ylhoo.com>
>> > wrote:
>> >
>> >>> There are good and bad-sounding cards out there. But I wouldn't
>> >>> worry too much about this particular bit of snake-oil. You've
>> >>> picked it up from an audiophile review or advert? Come on over to
>> >>> the pro audio world. You can still spend a lot of money if you
>> >>> insist, but you'll get more for it than in the audiophile arena :-)
>> >>>
>> >>
>> >>I have actually picked it up from reviewing schematics of CD players
>> >>and stand alone DACs that I own or have considered owning.
>> >
>> > Yeah. But is it a marketing ploy, or is it actually solving a real
>> > problem?
>> >
>>
>> As far as I am concerned it does make a difference. Don't believe me?
>> Fine don't. I really don't care. Either the card I am looking for
>> exists or it doesn't. Unfortunately it appears it does not. So I am
>> going to have to start from scratch pouring over spec sheets.
>
> Look. Just about any modern sound card will use a differential output
> DAC.
>
> The sound quality isues will lie elsewhere. Like good grounding design
> and the use of decent pro-audio grade op-amps for the ins and outs.
>
> The quality of the *connectors* is actually very important too. Mini
> jacks don't cut it !
>
>
>> The pro cards have more capabilities than what I would ever need but I
>> fear that they pro cards are geared toward 600 ohm balanced and I need
>> high impedance (~50k ohm) unbalanced as well as 600 ohms balanced.
>
> Apparently you also don't realise that so-called '600 ohm' ( a misnomer
> btw ) circuits work just fine with Hi-Z too.
>
> If you have Hi-Z gear ( with its lower performance ) why are you
> agonising over DACs ?
>
>
> Graham
>
>

Graham, Sorry if i was a bit terse with the comment about 'not caring if
you believe me or not'. It was not directed at you.

I have some old hi-z gear that was fairly well designed. Preamp
distortion is at 0.02% and hum and noise at 90db or so. It has served me
well and continues to do so. For me to replace it would cost a few grand.
However, if I try to drive a low impedance (600 ohms or so) device with
my preamp, it causes the low frequencies to be rolled off. I have
experienced this same effect with other gear as well. I realize that a
low-Z source driving a Hi-Z load isn't a problem generally as 600 ohm
resistors are cheap. My amp has Hi-Z unbalanced inputs only but is fairly
decent as well. Distortion is better than 0.02% with hum and noise levels
at 100db or so. I see no reason to change the system and to do so would
be rather pricey.

I changed from a Denon DCD1520 CD player to a Nakamichi based unit that
uses twin stereo DACs in a parallel configuration. I was and sill am
quite pleased at the positive sound quality compared to the Denon. I also
notice that McIntosh's latest stand alone DAC features DAC's in parallel.
As a matter of fact they use 8 separate DACs in a twin parallel DAC
configuration. I am starting to build a PC based audio source and was
trying to find a sound card with the same positive attributes my CDP has
and it seemed that specifying dual DACs was a logical place to start. I
have listened to a few sound cards and the ones I listened to caused
listeners fatigue in varying degrees. I experience no listeners fatigue
while listening to the Nak. They also have varying levels of something I
call digital grunge as well. I realize that dual dacs have nothing to do
with grunge and everything to do with decoupling. The Nakamicki features
a choke and two caps at every chip's B+/VCC line and my opinion is that it
is those components that reduce the grunge.

As you might guess, I listen to classical music at least 90% of the time.
So you see, I have had good experiences with dual dacs in parallel and
as such I wanted to go with something similar.

r




--
Nothing beats the bandwidth of a station wagon filled with DLT tapes.
Anonymous
December 17, 2004 10:31:39 AM

Archived from groups: rec.audio.opinion,rec.audio.tech (More info?)

On Fri, 17 Dec 2004 03:04:23 GMT, "Rich.Andrews" <spmaway@ylhoo.com>
wrote:

>Pooh Bear <rabbitsfriendsandrelations@hotmail.com> wrote in
>news:41C23470.999D67F7@hotmail.com:
>
>> R wrote:
>>
>>> "Arny Krueger" <arnyk@hotpop.com> wrote in news:qZ-dnTNPju7CgF_cRVn-
>>> og@comcast.com:
>>>
>>> > "Rich.Andrews" <spmaway@ylhoo.com> wrote in message
>>> > news:Xns95C1AD140A87Bbvzxrpl@10.232.1.1
>>> >
>>> >> I don't believe the count is relevant. The point is that putting
>>> >> two dacs in parallel lowers distortion and I feel that if I am going
>>> >> to spend some money, I might as well spend a bit more and get the
>>> >> best.

In that case, forget sound cards and use a Benchmark DAC-1.

>>> > In audio interfaces, AFAIK "The Best" is the LynxTWO.

>>> An input impedance of 24 ohms balanced and 12 ohms unbalanced? Isn't
>>> that a bit low?
>>>
>> Apparently you can't read a spec sheet.
>>
>> Input Impedance Balanced mode: 24 kW , Unbalanced mode: 12 kW ( the
>> ohms symbol appears as W in plain text btw ).
>>
>> http://www.lynxstudio.com/lynxtwospecs.html
>>
>> IIRC - most modern converters work differentially internally anyway. The
>> inputs and outputs on the converters I'm currently using are
>> differential and most others I've looked at are too. Those that are
>> 'single ended' usually have an internal inverting stage that converts
>> them to internally differential.
>>
>> You're worrying about non-issues.
>>
>http://lynxstudio.com/reviews/LynxTWOBrochureLoRes.pdf
>
>Clearly says "Unbalanced Mode: 12 <greek omega>"
>
>That means 12 ohms, not 12k ohms.
>
>What were you saying about reading a spec sheet?

You're reading different sheets. The input impedance is 24k ohms
balanced, the one you quote is simply a misprint.
--

Stewart Pinkerton | Music is Art - Audio is Engineering
!