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Volume Control ...

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Anonymous
June 10, 2004 4:03:23 PM

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

I'm hoping someone here might be able to help me out a little with this
project I'm working on. I have a Left and Right RCA Audio output that's fed
directly into a speaker amp, unfortunately, the speaker amp does not have
volume control. I'm hoping I could build something to go between the output
and input to control the volume. Is it simply a matter of just inserting a
variable resister (potentiometer)? Is that all there is to controlling
volume on an RCA audio signal? If so, what are the ohm ranges? Obviously 0
ohms for full volume, but how many do I need to make it silent? Also should
I use a linear pot or logarithmic pot?

Or, if something like this already exists (and has a remote control to
control the volume), please let me know, cause I'll just buy it instead of
making it.

Thanks,
Harry

More about : volume control

Anonymous
June 10, 2004 4:03:24 PM

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

In article <10ch1fl9mqjc9e4@corp.supernews.com>, Harry Muscle
<fake@AT@e-mail.com> wrote:

> I'm hoping someone here might be able to help me out a little with this
> project I'm working on. I have a Left and Right RCA Audio output that's fed
> directly into a speaker amp, unfortunately, the speaker amp does not have
> volume control. I'm hoping I could build something to go between the output
> and input to control the volume. Is it simply a matter of just inserting a
> variable resister (potentiometer)? Is that all there is to controlling
> volume on an RCA audio signal? If so, what are the ohm ranges? Obviously 0
> ohms for full volume, but how many do I need to make it silent? Also should
> I use a linear pot or logarithmic pot?

You can do a google search to come up with ideas. Any larger sized
pot would do, anything from 50K ohm to 100K ohm would do the trick.
Most folks prefer the action of a log taper, but in practice, the
log taper varies from pot to pot, so the right and left might be
different volume at some spots. Using a linear pot taper avoids
that problem.

> Or, if something like this already exists (and has a remote control to
> control the volume), please let me know, cause I'll just buy it instead of
> making it.

You can buy cheap stereo receivers with remote control via E-bay
or one of the discount on-line sites. You need one that has
pre-amp out/power amp in jacks. A remote control per-amp would be
even better.

-john-

--
====================================================================
John A. Weeks III 952-432-2708 john@johnweeks.com
Newave Communications http://www.johnweeks.com
====================================================================
Anonymous
June 10, 2004 5:26:42 PM

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

Harry Muscle wrote:

> I'm hoping someone here might be able to help me out a little with
> this project I'm working on. I have a Left and Right RCA Audio
> output that's fed directly into a speaker amp, unfortunately, the
> speaker amp does not have volume control. I'm hoping I could build
> something to go between the output and input to control the volume.

Probably. Tell us something about the source of this signal.

> Is it simply a matter of just inserting a variable resister
> (potentiometer)?

Could be.

> Is that all there is to controlling volume on an RCA audio signal?

In many cases, yes.

> If so, what are the ohm ranges?

Depends on the source and the load. If I was going to pick a number for
most modern applications, say 5 K ohms.

>Obviously 0 ohms for full volume, but how many do I need to make it
silent?

Potentiometers are typically hooked across full signal and ground, and the
slider selects a voltage at either extreme, and those in-between.

> Also should I use a linear pot or logarithmic pot?

Logrithmic.

> Or, if something like this already exists (and has a remote control to
> control the volume), please let me know, cause I'll just buy it
> instead of making it.

The "already exists" device is called a passive controller, and generally
ain't cheap unless you built it for yourself.
Related resources
Anonymous
June 10, 2004 7:55:15 PM

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

Mouser.com part number 313-2420-x Dual Ganged Audio taper potentiometer
(where x is the value - 1k, 10k, etc.)


"Harry Muscle" <fake@AT@e-mail.com> wrote in message
news:10ch1fl9mqjc9e4@corp.supernews.com...
> I'm hoping someone here might be able to help me out a little with this
> project I'm working on. I have a Left and Right RCA Audio output that's
fed
> directly into a speaker amp, unfortunately, the speaker amp does not have
> volume control. I'm hoping I could build something to go between the
output
> and input to control the volume. Is it simply a matter of just inserting
a
> variable resister (potentiometer)? Is that all there is to controlling
> volume on an RCA audio signal? If so, what are the ohm ranges? Obviously
0
> ohms for full volume, but how many do I need to make it silent? Also
should
> I use a linear pot or logarithmic pot?
>
> Or, if something like this already exists (and has a remote control to
> control the volume), please let me know, cause I'll just buy it instead of
> making it.
>
> Thanks,
> Harry
>
>
June 10, 2004 9:07:22 PM

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

Harry Muscle wrote:

> I'm hoping someone here might be able to help me out a little with this
> project I'm working on. I have a Left and Right RCA Audio output that's fed
> directly into a speaker amp, unfortunately, the speaker amp does not have
> volume control. I'm hoping I could build something to go between the output
> and input to control the volume. Is it simply a matter of just inserting a
> variable resister (potentiometer)? Is that all there is to controlling
> volume on an RCA audio signal? If so, what are the ohm ranges? Obviously 0
> ohms for full volume, but how many do I need to make it silent? Also should
> I use a linear pot or logarithmic pot?
>
> Or, if something like this already exists (and has a remote control to
> control the volume), please let me know, cause I'll just buy it instead of
> making it.
>
> Thanks,
> Harry
>
>

You could do that, but it's likely to affect frequency response unless
it's compensated. A better solution might be a cheap pre-amp if
fidelity matters. Or you could put something together with a dual
op-amp, in a way that lets the feedback loop take care of the response.

--
The e-mail address in our reply-to line is reversed in an attempt to
minimize spam. Our true address is of the form che...@prodigy.net.
Anonymous
June 10, 2004 9:07:23 PM

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

"CJT" <abujlehc@prodigy.net> wrote in message
news:40C89549.3020407@prodigy.net...
> Harry Muscle wrote:
>
> > I'm hoping someone here might be able to help me out a little with this
> > project I'm working on. I have a Left and Right RCA Audio output that's
fed
> > directly into a speaker amp, unfortunately, the speaker amp does not
have
> > volume control. I'm hoping I could build something to go between the
output
> > and input to control the volume. Is it simply a matter of just
inserting a
> > variable resister (potentiometer)? Is that all there is to controlling
> > volume on an RCA audio signal? If so, what are the ohm ranges?
Obviously 0
> > ohms for full volume, but how many do I need to make it silent? Also
should
> > I use a linear pot or logarithmic pot?
> >
> > Or, if something like this already exists (and has a remote control to
> > control the volume), please let me know, cause I'll just buy it instead
of
> > making it.
> >
> > Thanks,
> > Harry
> >
> >
>
> You could do that, but it's likely to affect frequency response unless
> it's compensated. A better solution might be a cheap pre-amp if
> fidelity matters. Or you could put something together with a dual
> op-amp, in a way that lets the feedback loop take care of the response.
>
> --
> The e-mail address in our reply-to line is reversed in an at to
> minimize spam. Our true address is of the form che...@prodigy.net.

Just curious, how cheap of a pre-amp would do the job? I've never really
looked at pre-amps, so I have no clue as to prices for them.

Thanks,
Harry
June 10, 2004 9:52:35 PM

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

John A. Weeks III wrote:

> In article <10ch1fl9mqjc9e4@corp.supernews.com>, Harry Muscle
> <fake@AT@e-mail.com> wrote:
>
>
>>I'm hoping someone here might be able to help me out a little with this
>>project I'm working on. I have a Left and Right RCA Audio output that's fed
>>directly into a speaker amp, unfortunately, the speaker amp does not have
>>volume control. I'm hoping I could build something to go between the output
>>and input to control the volume. Is it simply a matter of just inserting a
>>variable resister (potentiometer)? Is that all there is to controlling
>>volume on an RCA audio signal? If so, what are the ohm ranges? Obviously 0
>>ohms for full volume, but how many do I need to make it silent? Also should
>>I use a linear pot or logarithmic pot?
>
>
> You can do a google search to come up with ideas. Any larger sized
> pot would do, anything from 50K ohm to 100K ohm would do the trick.

It depends on the situation. Too low a value will load the source.
Too high a value will be more susceptible to parasitic capacitance
effects on the frequency response, and noise.

> Most folks prefer the action of a log taper, but in practice, the
> log taper varies from pot to pot, so the right and left might be
> different volume at some spots. Using a linear pot taper avoids
> that problem.
>
>
>>Or, if something like this already exists (and has a remote control to
>>control the volume), please let me know, cause I'll just buy it instead of
>>making it.
>
>
> You can buy cheap stereo receivers with remote control via E-bay
> or one of the discount on-line sites. You need one that has
> pre-amp out/power amp in jacks. A remote control per-amp would be
> even better.
>
> -john-
>


--
The e-mail address in our reply-to line is reversed in an attempt to
minimize spam. Our true address is of the form che...@prodigy.net.
June 10, 2004 9:53:49 PM

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

Harry Muscle wrote:

> "CJT" <abujlehc@prodigy.net> wrote in message
> news:40C89549.3020407@prodigy.net...
>
>>Harry Muscle wrote:
>>
>>
>>>I'm hoping someone here might be able to help me out a little with this
>>>project I'm working on. I have a Left and Right RCA Audio output that's
>
> fed
>
>>>directly into a speaker amp, unfortunately, the speaker amp does not
>
> have
>
>>>volume control. I'm hoping I could build something to go between the
>
> output
>
>>>and input to control the volume. Is it simply a matter of just
>
> inserting a
>
>>>variable resister (potentiometer)? Is that all there is to controlling
>>>volume on an RCA audio signal? If so, what are the ohm ranges?
>
> Obviously 0
>
>>>ohms for full volume, but how many do I need to make it silent? Also
>
> should
>
>>>I use a linear pot or logarithmic pot?
>>>
>>>Or, if something like this already exists (and has a remote control to
>>>control the volume), please let me know, cause I'll just buy it instead
>
> of
>
>>>making it.
>>>
>>>Thanks,
>>>Harry
>>>
>>>
>>
>>You could do that, but it's likely to affect frequency response unless
>>it's compensated. A better solution might be a cheap pre-amp if
>>fidelity matters. Or you could put something together with a dual
>>op-amp, in a way that lets the feedback loop take care of the response.
>>
>>--
>>The e-mail address in our reply-to line is reversed in an at to
>>minimize spam. Our true address is of the form che...@prodigy.net.
>
>
> Just curious, how cheap of a pre-amp would do the job? I've never really
> looked at pre-amps, so I have no clue as to prices for them.
>
> Thanks,
> Harry
>
>

I haven't looked lately, but I wouldn't be surprised if something
acceptable could be found for under 50 bucks.

--
The e-mail address in our reply-to line is reversed in an attempt to
minimize spam. Our true address is of the form che...@prodigy.net.
Anonymous
June 10, 2004 10:23:09 PM

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

> Harry Muscle wrote:
> > Or, if something like this already exists (and has a remote control to
> > control the volume), please let me know, cause I'll just buy it instead
of
> > making it.

"CJT" wrote ...
> You could do that, but it's likely to affect frequency response unless
> it's compensated. A better solution might be a cheap pre-amp if
> fidelity matters. Or you could put something together with a dual
> op-amp, in a way that lets the feedback loop take care of the response.

The risk of audible anomolies is significantly greater from a
"cheap pre-amp" than from a conventional passive potentiometer.

The risk of spending too much to solve the problem is definitly
greater using a "cheap pre-amp" than assembling a passive
potentiometer in a metal box with two pair of RCA connectors.

The circuit is literally trivial and can be found in any number of
sources, both conventional and online.
June 11, 2004 5:33:17 AM

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

Richard Crowley wrote:

>>Harry Muscle wrote:
>>
>>>Or, if something like this already exists (and has a remote control to
>>>control the volume), please let me know, cause I'll just buy it instead
>
> of
>
>>>making it.
>
>
> "CJT" wrote ...
>
>>You could do that, but it's likely to affect frequency response unless
>>it's compensated. A better solution might be a cheap pre-amp if
>>fidelity matters. Or you could put something together with a dual
>>op-amp, in a way that lets the feedback loop take care of the response.
>
>
> The risk of audible anomolies is significantly greater from a
> "cheap pre-amp" than from a conventional passive potentiometer.

It's true that the shortcomings of a passive potentiometer are
not anomalous -- they're well known and fairly easy to characterize.
But that wasn't my point.

>
> The risk of spending too much to solve the problem is definitly
> greater using a "cheap pre-amp" than assembling a passive
> potentiometer in a metal box with two pair of RCA connectors.
>

Yes, pots are cheap.

> The circuit is literally trivial and can be found in any number of
> sources, both conventional and online.
>
>

And the circuit is trivial. That doesn't mean it's good.


--
The e-mail address in our reply-to line is reversed in an attempt to
minimize spam. Our true address is of the form che...@prodigy.net.
Anonymous
June 11, 2004 5:33:18 AM

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

> Yes, pots are cheap.
>
> > The circuit is literally trivial and can be found in any number of
> > sources, both conventional and online.
>
> And the circuit is trivial. That doesn't mean it's good.

Huh? It is precisely the same circuit used equipment of every
possible description from $3 radios to $3,000,000 audio systems.

The same circuit used in "passive preamps" costing hundreds
(even thousands) of dollars.
June 11, 2004 6:12:47 AM

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

Richard Crowley wrote:

>>Yes, pots are cheap.
>>
>>
>>>The circuit is literally trivial and can be found in any number of
>>>sources, both conventional and online.
>>
>>And the circuit is trivial. That doesn't mean it's good.
>
>
> Huh? It is precisely the same circuit used equipment of every
> possible description from $3 radios to $3,000,000 audio systems.
>
> The same circuit used in "passive preamps" costing hundreds
> (even thousands) of dollars.
>
>
I assume you're being deliberately dense on this for some reason unknown
to me. My point was simply that a simple potentiometer, in conjunction
with parasitic capacitance, is a filter. As such, it can affect
fidelity. Of course, the devil is in the details. But an earlier post
in this thread suggested, as I recall, pots in the 100K ohm range.

In a pre-amp, the designer has some control over the impedances involved
and the circuit configuration, and can compensate for these effects.
That's not to say all do, of course, and perhaps the really cheap ones
don't. If that's your point, then maybe we're not far from agreement.
But that's why my original post in this thread was worded the way it
was.

Tell me why you disagree. But I'm not impressed by arguments based on
"passive preamps" unless accompanied by significant detail about the
circuits involved. Nor am I convinced by your apparent claim that every
audio system simply ignores the issue and uses the precise same circuit.

--
The e-mail address in our reply-to line is reversed in an attempt to
minimize spam. Our true address is of the form che...@prodigy.net.
Anonymous
June 11, 2004 6:12:48 AM

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

"CJT" <abujlehc@prodigy.net> wrote in message
news:40C9151F.3060103@prodigy.net...
> Richard Crowley wrote:
>
> >>Yes, pots are cheap.
> >>
> >>
> >>>The circuit is literally trivial and can be found in any number of
> >>>sources, both conventional and online.
> >>
> >>And the circuit is trivial. That doesn't mean it's good.
> >
> >
> > Huh? It is precisely the same circuit used equipment of every
> > possible description from $3 radios to $3,000,000 audio systems.
> >
> > The same circuit used in "passive preamps" costing hundreds
> > (even thousands) of dollars.
> >
> >
> I assume you're being deliberately dense on this for some reason unknown
> to me. My point was simply that a simple potentiometer, in conjunction
> with parasitic capacitance, is a filter. As such, it can affect
> fidelity. Of course, the devil is in the details. But an earlier post
> in this thread suggested, as I recall, pots in the 100K ohm range.

We agree that recommending something like a 100K pot for what
would appear to be conventional consumer line-level use is not
appropriate. My assumption of consumer line-levels is ~<1K source
impedance and ~>10K input impedances.

I would wager a nice dinner that it would be impossible for the OP
to detect any difference between a reasonable-quality 10K passive
pot in a simple shielded enclosure and the most expensive solution
you could suggest.

> In a pre-amp, the designer has some control over the impedances involved
> and the circuit configuration, and can compensate for these effects.
> That's not to say all do, of course, and perhaps the really cheap ones
> don't. If that's your point, then maybe we're not far from agreement.
> But that's why my original post in this thread was worded the way it
> was.
>
> Tell me why you disagree.

I don't disagree. But IMHO you are significantly overblowing the
level of the original question. Everything you wrote was true, but
seems to offer little of practical value to the OP.
June 11, 2004 6:36:07 AM

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

Richard Crowley wrote:

> "CJT" <abujlehc@prodigy.net> wrote in message
> news:40C9151F.3060103@prodigy.net...
>
>>Richard Crowley wrote:
>>
>>
>>>>Yes, pots are cheap.
>>>>
>>>>
>>>>
>>>>>The circuit is literally trivial and can be found in any number of
>>>>>sources, both conventional and online.
>>>>
>>>>And the circuit is trivial. That doesn't mean it's good.
>>>
>>>
>>>Huh? It is precisely the same circuit used equipment of every
>>>possible description from $3 radios to $3,000,000 audio systems.
>>>
>>>The same circuit used in "passive preamps" costing hundreds
>>>(even thousands) of dollars.
>>>
>>>
>>
>>I assume you're being deliberately dense on this for some reason unknown
>>to me. My point was simply that a simple potentiometer, in conjunction
>>with parasitic capacitance, is a filter. As such, it can affect
>>fidelity. Of course, the devil is in the details. But an earlier post
>>in this thread suggested, as I recall, pots in the 100K ohm range.
>
>
> We agree that recommending something like a 100K pot for what
> would appear to be conventional consumer line-level use is not
> appropriate. My assumption of consumer line-levels is ~<1K source
> impedance and ~>10K input impedances.
>
> I would wager a nice dinner that it would be impossible for the OP
> to detect any difference between a reasonable-quality 10K passive
> pot in a simple shielded enclosure and the most expensive solution
> you could suggest.
>
>
>>In a pre-amp, the designer has some control over the impedances involved
>>and the circuit configuration, and can compensate for these effects.
>>That's not to say all do, of course, and perhaps the really cheap ones
>>don't. If that's your point, then maybe we're not far from agreement.
>>But that's why my original post in this thread was worded the way it
>>was.
>>
>>Tell me why you disagree.
>
>
> I don't disagree. But IMHO you are significantly overblowing the
> level of the original question. Everything you wrote was true, but
> seems to offer little of practical value to the OP.
>
>
Fair enough. I'm not sure how we seem to have got crosswise, but it
might relate to the context in which I first posted, at which time the
only reply on the board was suggesting a 100k pot. That probably
colored my thinking toward a more consumer failsafe option.

Of course, we don't really know much about the OP's "project," either
....

:-)


--
The e-mail address in our reply-to line is reversed in an attempt to
minimize spam. Our true address is of the form che...@prodigy.net.
June 11, 2004 9:29:03 AM

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

In article <40C8A02C.5020900@prodigy.net>, CJT <abujlehc@prodigy.net> wrote:
>Harry Muscle wrote:
>
>> "CJT" <abujlehc@prodigy.net> wrote in message
>> news:40C89549.3020407@prodigy.net...
>>
>>>Harry Muscle wrote:
>>>
>>>
>>>>I'm hoping someone here might be able to help me out a little with this
>>>>project I'm working on. I have a Left and Right RCA Audio output that's
>>
>> fed
>>
>>>>directly into a speaker amp, unfortunately, the speaker amp does not
>>
>> have
>>
>>>>volume control. I'm hoping I could build something to go between the
>>
>> output
>>
>>>>and input to control the volume. Is it simply a matter of just
>>
>> inserting a
>>
>>>>variable resister (potentiometer)? Is that all there is to controlling
>>>>volume on an RCA audio signal? If so, what are the ohm ranges?
>>
>> Obviously 0
>>
>>>>ohms for full volume, but how many do I need to make it silent? Also
>>
>> should
>>
>>>>I use a linear pot or logarithmic pot?
>>>>
>>>>Or, if something like this already exists (and has a remote control to
>>>>control the volume), please let me know, cause I'll just buy it instead
>>
>> of
>>
>>>>making it.
>>>>
>>>>Thanks,
>>>>Harry
>>>>
>>>>
>>>
>>>You could do that, but it's likely to affect frequency response unless
>>>it's compensated. A better solution might be a cheap pre-amp if
>>>fidelity matters. Or you could put something together with a dual
>>>op-amp, in a way that lets the feedback loop take care of the response.
>>>
>>>--
>>>The e-mail address in our reply-to line is reversed in an at to
>>>minimize spam. Our true address is of the form che...@prodigy.net.
>>
>>
>> Just curious, how cheap of a pre-amp would do the job? I've never really
>> looked at pre-amps, so I have no clue as to prices for them.
>>
>> Thanks,
>> Harry
>>
>>
>
>I haven't looked lately, but I wouldn't be surprised if something
>acceptable could be found for under 50 bucks.
>
Just get on ebay one of those elcheapo audio/video mixer boxes
Anonymous
June 13, 2004 12:38:24 AM

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

>I'm hoping someone here might be able to help me out a little with this
>project I'm working on. I have a Left and Right RCA Audio output that's
>fed
>directly into a speaker amp, unfortunately, the speaker amp does not have
>volume control. I'm hoping I could build something to go between the output
>and input to control the volume. Is it simply a matter of just inserting
>a
>variable resister (potentiometer)? Is that all there is to controlling
>volume on an RCA audio signal? If so, what are the ohm ranges? Obviously
>0
>ohms for full volume, but how many do I need to make it silent? Also should
>I use a linear pot or logarithmic pot?
>
>Or, if something like this already exists (and has a remote control to
>control the volume), please let me know, cause I'll just buy it instead
>of
>making it.
>
>Thanks,
>Harry
>
>
>

10K ohms will be suficient, commonly available and easy to wire.

It is set up as an L pad Input wire to one terminal of the fader, output to
center slider and ground to last tap. Repeat for the other channel
Richard H. Kuschel
"I canna change the law of physics."-----Scotty
June 13, 2004 1:48:20 AM

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

Richard Kuschel wrote:

>>I'm hoping someone here might be able to help me out a little with this
>>project I'm working on. I have a Left and Right RCA Audio output that's
>>fed
>>directly into a speaker amp, unfortunately, the speaker amp does not have
>>volume control. I'm hoping I could build something to go between the output
>>and input to control the volume. Is it simply a matter of just inserting
>>a
>>variable resister (potentiometer)? Is that all there is to controlling
>>volume on an RCA audio signal? If so, what are the ohm ranges? Obviously
>>0
>>ohms for full volume, but how many do I need to make it silent? Also should
>>I use a linear pot or logarithmic pot?
>>
>>Or, if something like this already exists (and has a remote control to
>>control the volume), please let me know, cause I'll just buy it instead
>>of
>>making it.
>>
>>Thanks,
>>Harry
>>
>>
>>
>
>
> 10K ohms will be suficient, commonly available and easy to wire.
>
> It is set up as an L pad Input wire to one terminal of the fader, output to
> center slider and ground to last tap. Repeat for the other channel
> Richard H. Kuschel
> "I canna change the law of physics."-----Scotty

What you describe (a simple potentiometer, without more) is not an
L-pad.

http://www.bcae1.com/lpad.htm

--
The e-mail address in our reply-to line is reversed in an attempt to
minimize spam. Our true address is of the form che...@prodigy.net.
Anonymous
June 13, 2004 4:06:28 AM

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

On Sat, 12 Jun 2004 21:48:20 GMT, CJT <abujlehc@prodigy.net> wrote:

>> 10K ohms will be suficient, commonly available and easy to wire.
>>
>> It is set up as an L pad Input wire to one terminal of the fader, output to
>> center slider and ground to last tap. Repeat for the other channel
>> Richard H. Kuschel
>> "I canna change the law of physics."-----Scotty
>
>What you describe (a simple potentiometer, without more) is not an
>L-pad.
>
>http://www.bcae1.com/lpad.htm

A simple potentiometer, configured as a normal volume control *is* an
L pad. The part above the slider is the flat part of the L, the part
below the slider is the vertical part of the L.

d
Pearce Consulting
http://www.pearce.uk.com
Anonymous
June 15, 2004 10:32:34 PM

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

Harry Muscle <fake@AT@e-mail.com> wrote:

>Or, if something like this already exists (and has a remote control to
>control the volume), please let me know, cause I'll just buy it instead of
>making it.

Adcom SLC-505 (no remote control).

Also, I know that there a manufacture making a passive pre-amp with a
remote volume control: I dog-eared the page of a magazine recently --
now if I could only remember which one!

--
Len Moskowitz PDAudio, Binaural Mics, Cables, DPA, M-Audio
Core Sound http://www.stealthmicrophones.com
Teaneck, New Jersey USA http://www.core-sound.com
moskowit@core-sound.com Tel: 201-801-0812, FAX: 201-801-0912
Anonymous
June 20, 2004 7:20:24 PM

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

Just to clarify, do you mean to add resistance to attenuate? Or do you
mean to have the pot shorting from signal to ground? That (the second)
is the approach used in most audio equipment. No one has explained
this, and I think the OP was thinking the other way. In the shorting
approach, 10k might be too little. (Of course it is hard to say
without more info and a EE degree). I made this very thing long ago
from a 47k dual log pot (that had been the mic gain control in a
cassette deck I found in the trash). I put a 6 foot stereo wire on it
with both a male and female RCA plug at the end of each signal lead.
It can then connect easily between any source device and the power
amp. It was cheaper than buying a home theater sound system with a
remote (my pre-remote control Proton receiver still sounds fine), and
I sometimes find it handy for other applications.

Robobass

> 10K ohms will be suficient, commonly available and easy to wire.
>
> It is set up as an L pad Input wire to one terminal of the fader, output to
> center slider and ground to last tap. Repeat for the other channel
> Richard H. Kuschel
> "I canna change the law of physics."-----Scotty
Anonymous
June 21, 2004 11:29:31 AM

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

> > 10K ohms will be suficient, commonly available and easy to wire.
> >
> > It is set up as an L pad Input wire to one terminal of the fader,
output to
> > center slider and ground to last tap. Repeat for the other channel
> > Richard H. Kuschel
> > "I canna change the law of physics."-----Scotty

"robobass" wrote ...
> Just to clarify, do you mean to add resistance to attenuate? Or do you
> mean to have the pot shorting from signal to ground?

An L-pad (or potentiometer) is neither/both.
It is both a series (inline) resistance AND a parallel (shunt)
resistance. A pot allows you to continuously vary the ratio
of the two.
Anonymous
June 21, 2004 7:04:29 PM

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

Thanks. My description was incomplete. As you attenuate you short the
input to ground. and after further consideration, I agree that 10k is
a good number.
Robobass

> 10K ohms will be suficient, commonly available and easy to wire.
>
> It is set up as an L pad Input wire to one terminal of the fader, output to
> center slider and ground to last tap. Repeat for the other channel
> Richard H. Kuschel
> "I canna change the law of physics."-----Scotty
June 22, 2004 7:17:21 AM

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

Don Pearce wrote:

> On Sat, 12 Jun 2004 21:48:20 GMT, CJT <abujlehc@prodigy.net> wrote:
>
>
>>>10K ohms will be suficient, commonly available and easy to wire.
>>>
>>>It is set up as an L pad Input wire to one terminal of the fader, output to
>>>center slider and ground to last tap. Repeat for the other channel
>>>Richard H. Kuschel
>>>"I canna change the law of physics."-----Scotty
>>
>>What you describe (a simple potentiometer, without more) is not an
>>L-pad.
>>
>>http://www.bcae1.com/lpad.htm
>
>
> A simple potentiometer, configured as a normal volume control *is* an
> L pad. The part above the slider is the flat part of the L, the part
> below the slider is the vertical part of the L.
>
> d
> Pearce Consulting
> http://www.pearce.uk.com

An L pad is configured to maintain constant impedance. A simple pot is not.


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Anonymous
June 22, 2004 11:14:28 AM

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

On Tue, 22 Jun 2004 03:17:21 GMT, CJT <abujlehc@prodigy.net> wrote:

>Don Pearce wrote:
>
>> On Sat, 12 Jun 2004 21:48:20 GMT, CJT <abujlehc@prodigy.net> wrote:
>>
>>
>>>>10K ohms will be suficient, commonly available and easy to wire.
>>>>
>>>>It is set up as an L pad Input wire to one terminal of the fader, output to
>>>>center slider and ground to last tap. Repeat for the other channel
>>>>Richard H. Kuschel
>>>>"I canna change the law of physics."-----Scotty
>>>
>>>What you describe (a simple potentiometer, without more) is not an
>>>L-pad.
>>>
>>>http://www.bcae1.com/lpad.htm
>>
>>
>> A simple potentiometer, configured as a normal volume control *is* an
>> L pad. The part above the slider is the flat part of the L, the part
>> below the slider is the vertical part of the L.
>>
>> d
>> Pearce Consulting
>> http://www.pearce.uk.com
>
>An L pad is configured to maintain constant impedance. A simple pot is not.

"L pad" describes the shape of the configuration - ie just like a pot.
Whether you choose to configure it for constant impedance or not is
entirely a matter of choice.

d
Pearce Consulting
http://www.pearce.uk.com
June 22, 2004 11:14:29 AM

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

Don Pearce wrote:
> On Tue, 22 Jun 2004 03:17:21 GMT, CJT <abujlehc@prodigy.net> wrote:
>
>
>>Don Pearce wrote:
>>
>>
>>>On Sat, 12 Jun 2004 21:48:20 GMT, CJT <abujlehc@prodigy.net> wrote:
>>>
>>>
>>>
>>>>>10K ohms will be suficient, commonly available and easy to wire.
>>>>>
>>>>>It is set up as an L pad Input wire to one terminal of the fader, output to
>>>>>center slider and ground to last tap. Repeat for the other channel
>>>>>Richard H. Kuschel
>>>>>"I canna change the law of physics."-----Scotty
>>>>
>>>>What you describe (a simple potentiometer, without more) is not an
>>>>L-pad.
>>>>
>>>>http://www.bcae1.com/lpad.htm
>>>
>>>
>>>A simple potentiometer, configured as a normal volume control *is* an
>>>L pad. The part above the slider is the flat part of the L, the part
>>>below the slider is the vertical part of the L.
>>>
>>>d
>>>Pearce Consulting
>>>http://www.pearce.uk.com
>>
>>An L pad is configured to maintain constant impedance. A simple pot is not.
>
>
> "L pad" describes the shape of the configuration - ie just like a pot.
> Whether you choose to configure it for constant impedance or not is
> entirely a matter of choice.
>
> d
> Pearce Consulting
> http://www.pearce.uk.com

Did you read the page I cited?

Are you trying to make an "Alice in Wonderland" argument
(i.e. words mean what you say they mean)? Or are you
willing to use the time-honored terminology the rest of
the world uses?

--
The e-mail address in our reply-to line is reversed in an attempt to
minimize spam. Our true address is of the form che...@prodigy.net.
Anonymous
June 22, 2004 12:07:39 PM

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

On Tue, 22 Jun 2004 06:57:19 GMT, CJT <abujlehc@prodigy.net> wrote:

>>>>>http://www.bcae1.com/lpad.htm
>>>>
>>>>
>>>>A simple potentiometer, configured as a normal volume control *is* an
>>>>L pad. The part above the slider is the flat part of the L, the part
>>>>below the slider is the vertical part of the L.
>>>>
>>>>d
>>>>Pearce Consulting
>>>>http://www.pearce.uk.com
>>>
>>>An L pad is configured to maintain constant impedance. A simple pot is not.
>>
>>
>> "L pad" describes the shape of the configuration - ie just like a pot.
>> Whether you choose to configure it for constant impedance or not is
>> entirely a matter of choice.
>>
>> d
>> Pearce Consulting
>> http://www.pearce.uk.com
>
>Did you read the page I cited?
>
>Are you trying to make an "Alice in Wonderland" argument
>(i.e. words mean what you say they mean)? Or are you
>willing to use the time-honored terminology the rest of
>the world uses?

Sorry - just went and looked at your "citation". Barely stopped myself
laughing. If the best authority for your assertion is somebody doing
car audio gear, then please think again. I think I made my first "L"
pad back in the 1960's. Used them again and again and again whilst
designing high performance test and measuring equipment for Marconi.
They are matched, or not matched, at the designers choice. You want a
reference for a citation? Please - use me.

d
Pearce Consulting
http://www.pearce.uk.com
June 22, 2004 10:48:40 PM

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

Don Pearce wrote:

> On Tue, 22 Jun 2004 06:57:19 GMT, CJT <abujlehc@prodigy.net> wrote:
>
>
>>>>>>http://www.bcae1.com/lpad.htm
>>>>>
>>>>>
>>>>>A simple potentiometer, configured as a normal volume control *is* an
>>>>>L pad. The part above the slider is the flat part of the L, the part
>>>>>below the slider is the vertical part of the L.
>>>>>
>>>>>d
>>>>>Pearce Consulting
>>>>>http://www.pearce.uk.com
>>>>
>>>>An L pad is configured to maintain constant impedance. A simple pot is not.
>>>
>>>
>>>"L pad" describes the shape of the configuration - ie just like a pot.
>>>Whether you choose to configure it for constant impedance or not is
>>>entirely a matter of choice.
>>>
>>>d
>>>Pearce Consulting
>>>http://www.pearce.uk.com
>>
>>Did you read the page I cited?
>>
>>Are you trying to make an "Alice in Wonderland" argument
>>(i.e. words mean what you say they mean)? Or are you
>>willing to use the time-honored terminology the rest of
>>the world uses?
>
>
> Sorry - just went and looked at your "citation". Barely stopped myself
> laughing. If the best authority for your assertion is somebody doing
> car audio gear, then please think again. I think I made my first "L"
> pad back in the 1960's. Used them again and again and again whilst
> designing high performance test and measuring equipment for Marconi.
> They are matched, or not matched, at the designers choice. You want a
> reference for a citation? Please - use me.

OK, what's your favorite?

I did a Google search, and it does seem some people have relaxed the
definition to include just about any attenuator in the definition.
To me, that just seems sloppy, but c'est la vie.

>
> d
> Pearce Consulting
> http://www.pearce.uk.com


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