I have found a "reverse RIAA" module

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

On Sun, 28 Nov 2004 09:10:00 -0500, Bill <bill2@mindspring.com> wrote:

>I found at http://www.hagtech.com/ a "reverse RIAA" module for
>allowing line sources into phono inputs. It reverses the frequency
>response curve and pads the level to around minus 50-60.

But did you find a reason why anyone would wish to do this - aside
from testing an RIAA preamp?

--

Stewart Pinkerton | Music is Art - Audio is Engineering

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

"Stewart Pinkerton" <patent3@dircon.co.uk> wrote in message
news:q7sjq0lttc1ggivkjb3kfiroe6re41bedr@4ax.com...
> On Sun, 28 Nov 2004 09:10:00 -0500, Bill <bill2@mindspring.com> wrote:
>
>>I found at http://www.hagtech.com/ a "reverse RIAA" module for
>>allowing line sources into phono inputs. It reverses the frequency
>>response curve and pads the level to around minus 50-60.
>
> But did you find a reason why anyone would wish to do this - aside
> from testing an RIAA preamp?

He said that he needed another line input and had only the
mag phono input left on his device. An inverse RIAA pad/
filter is appropriate if he can't just re-wire his device or
use an external switch. Hope he doesn't have particularly
high expectations of how it will sound relative to a regular
line input.

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

Bill wrote:

> I found at http://www.hagtech.com/ a "reverse RIAA" module for
> allowing line sources into phono inputs. It reverses the frequency
> response curve and pads the level to around minus 50-60.

That's how we test RIAA inputs ! I didn't need some commercial company
to tell me how to do it though.


Graham

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

"Pooh Bear" <rabbitsfriendsandrelations@hotmail.com> wrote in message
news:41AA459D.47FB8FB6@hotmail.com...
> Richard Crowley wrote:
>
>> "Stewart Pinkerton" <patent3@dircon.co.uk> wrote in message
>> news:q7sjq0lttc1ggivkjb3kfiroe6re41bedr@4ax.com...
>> > On Sun, 28 Nov 2004 09:10:00 -0500, Bill <bill2@mindspring.com> wrote:
>> >
>> >>I found at http://www.hagtech.com/ a "reverse RIAA" module for
>> >>allowing line sources into phono inputs. It reverses the frequency
>> >>response curve and pads the level to around minus 50-60.
>> >
>> > But did you find a reason why anyone would wish to do this - aside
>> > from testing an RIAA preamp?
>>
>> He said that he needed another line input and had only the
>> mag phono input left on his device. An inverse RIAA pad/
>> filter is appropriate if he can't just re-wire his device or
>> use an external switch. Hope he doesn't have particularly
>> high expectations of how it will sound relative to a regular
>> line input.
>
> Indeed ! It'll be somewhat second rate at best, rather noisy, and the
> response won't be exactly flat due to component tolerancing affecting the
> response curves.

And yet, more accurate and quieter than vinyl!

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

"Pooh Bear" <rabbitsfriendsandrelations@hotmail.com> wrote in message
news:41AA59C1.4642082E@hotmail.com...
>
> Karl Uppiano wrote:
>
>> "Pooh Bear" <rabbitsfriendsandrelations@hotmail.com> wrote in message
>> news:41AA459D.47FB8FB6@hotmail.com...
>> > Richard Crowley wrote:
>> >
>> >> "Stewart Pinkerton" <patent3@dircon.co.uk> wrote in message
>> >> news:q7sjq0lttc1ggivkjb3kfiroe6re41bedr@4ax.com...
>> >> > On Sun, 28 Nov 2004 09:10:00 -0500, Bill <bill2@mindspring.com>
>> >> > wrote:
>> >> >
>> >> >>I found at http://www.hagtech.com/ a "reverse RIAA" module for
>> >> >>allowing line sources into phono inputs. It reverses the frequency
>> >> >>response curve and pads the level to around minus 50-60.
>> >> >
>> >> > But did you find a reason why anyone would wish to do this - aside
>> >> > from testing an RIAA preamp?
>> >>
>> >> He said that he needed another line input and had only the
>> >> mag phono input left on his device. An inverse RIAA pad/
>> >> filter is appropriate if he can't just re-wire his device or
>> >> use an external switch. Hope he doesn't have particularly
>> >> high expectations of how it will sound relative to a regular
>> >> line input.
>> >
>> > Indeed ! It'll be somewhat second rate at best, rather noisy, and the
>> > response won't be exactly flat due to component tolerancing affecting
>> > the
>> > response curves.
>>
>> And yet, more accurate and quieter than vinyl!
>
> Sssshhh ! You're not supposed to say that ! You might hurt someone's
> opinions.
>
>
> Graham ;-)
>
>
I have a reverse RIAA custom built by McIntosh for authorized servicers to
repair their stuff in the old days. I think this one dates back to the
stereo tube units, judging by the small wirewound resistors with painted
color dots for the codes, etc. Interesting.

Mark Z.

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

"Isaac Wingfield" <isw@witzend.com> wrote in message
news:isw-8B55A3.19282028112004@netnews.comcast.net
> In article <41AA4505.D79F26EA@hotmail.com>,
> Pooh Bear <rabbitsfriendsandrelations@hotmail.com> wrote:
>
>> Bill wrote:
>>
>>> I found at http://www.hagtech.com/ a "reverse RIAA" module for
>>> allowing line sources into phono inputs. It reverses the frequency
>>> response curve and pads the level to around minus 50-60.
>>
>> That's how we test RIAA inputs ! I didn't need some commercial
>> company to tell me how to do it though.
>
> To have any hope at all of accuracy. the *only* way to test RIAA
> inputs is using a proper RIAA test record.
>
> If you don't include the cartridge in the test, it's worthless.

I thought we were talking about testing preamps, not cartridges.

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

"Isaac Wingfield" <isw@witzend.com> wrote in message
news:isw-8B55A3.19282028112004@netnews.comcast.net...
> In article <41AA4505.D79F26EA@hotmail.com>,
> Pooh Bear <rabbitsfriendsandrelations@hotmail.com> wrote:
>
>> Bill wrote:
>>
>> > I found at http://www.hagtech.com/ a "reverse RIAA" module for
>> > allowing line sources into phono inputs. It reverses the frequency
>> > response curve and pads the level to around minus 50-60.
>>
>> That's how we test RIAA inputs ! I didn't need some commercial company
>> to tell me how to do it though.
>
> To have any hope at all of accuracy. the *only* way to test RIAA inputs
> is using a proper RIAA test record.
>
> If you don't include the cartridge in the test, it's worthless.
>
> Isaac

Absolutely wrong. The reverse RIAA was provided to authorized servicers for
the purpose of testing and repairing phono preamp sections without having to
hook up a turntable, and accounting for the equalization so that EQ problems
would also be readily spotted. Even if it were just for testing frequency
response, it would still be useful for engineering and production purposes.

Another use which was barely mentioned in this thread was the very useful
task of hooking another line-level input to a receiver which doesn't have
enough of these. Tandberg and some earlier Onkyo models come to mind, since
they lacked enough auxiliary inputs. Yes, the addition of a device ahead of
the phono input would compromise ultimate fidelity compared to a regular
input, but even if this concerns you, a phono input could be used this way
for the audio output of a TV, game, or other lesser-quality signal.

Mark Z.

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

In article <41AA9E78.C2DDFAFA@hotmail.com>,
Pooh Bear <rabbitsfriendsandrelations@hotmail.com> wrote:

> Isaac Wingfield wrote:
>
> > In article <41AA4505.D79F26EA@hotmail.com>,
> > Pooh Bear <rabbitsfriendsandrelations@hotmail.com> wrote:
> >
> > > Bill wrote:
> > >
> > > > I found at http://www.hagtech.com/ a "reverse RIAA" module for
> > > > allowing line sources into phono inputs. It reverses the frequency
> > > > response curve and pads the level to around minus 50-60.
> > >
> > > That's how we test RIAA inputs ! I didn't need some commercial company
> > > to tell me how to do it though.
> >
> > To have any hope at all of accuracy. the *only* way to test RIAA inputs
> > is using a proper RIAA test record.
> >
> > If you don't include the cartridge in the test, it's worthless.
>
> And if you don't know what cartridge the user is going to attach....... ?
> What then ?

Then you really don't know what the system's performance is going to be.

Surely you don't imagine that a "calibrated" RIAA preamp will have the
same frequency response *from a record* regardless of which cartridge
you attach?

It's a very interesting experiment to use an inverse-RIAA network to
"calibrate" a preamp, and then hook up the cartridge of your choice and
check the response using the test record.

Most RIAA preamps are "pretty close" without calibration anyway. The
only reason to use the inverse network is to "fine tune" things, and if
you ignore the cartridge's effect when you do the tuning, you may wind
up further off than when you started.

Isaac

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

"Isaac Wingfield" <isw@witzend.com> wrote in message
news:isw-0179D5.20340029112004@netnews.comcast.net
> In article <41AA9E78.C2DDFAFA@hotmail.com>,
> Pooh Bear <rabbitsfriendsandrelations@hotmail.com> wrote:
>
>> Isaac Wingfield wrote:
>>
>>> In article <41AA4505.D79F26EA@hotmail.com>,
>>> Pooh Bear <rabbitsfriendsandrelations@hotmail.com> wrote:
>>>
>>>> Bill wrote:
>>>>
>>>>> I found at http://www.hagtech.com/ a "reverse RIAA" module for
>>>>> allowing line sources into phono inputs. It reverses the frequency
>>>>> response curve and pads the level to around minus 50-60.
>>>>
>>>> That's how we test RIAA inputs ! I didn't need some commercial
>>>> company to tell me how to do it though.
>>>
>>> To have any hope at all of accuracy. the *only* way to test RIAA
>>> inputs is using a proper RIAA test record.
>>>
>>> If you don't include the cartridge in the test, it's worthless.
>>
>> And if you don't know what cartridge the user is going to
>> attach....... ? What then ?
>
> Then you really don't know what the system's performance is going to
> be.

> Surely you don't imagine that a "calibrated" RIAA preamp will have the
> same frequency response *from a record* regardless of which cartridge
> you attach?

Agreed, but that is a different question.

> It's a very interesting experiment to use an inverse-RIAA network to
> "calibrate" a preamp, and then hook up the cartridge of your choice
> and check the response using the test record.

Been there, done that.

> Most RIAA preamps are "pretty close" without calibration anyway. The
> only reason to use the inverse network is to "fine tune" things, and
> if you ignore the cartridge's effect when you do the tuning, you may
> wind up further off than when you started.

Agreed.

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

On Sun, 28 Nov 2004 09:10:00 -0500, Bill <bill2@mindspring.com> wrote:

>I found at http://www.hagtech.com/ a "reverse RIAA" module for
>allowing line sources into phono inputs. It reverses the frequency
>response curve and pads the level to around minus 50-60.

Congratulations! Why?

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

"Geoff Wood" <geoff@nospam-paf.co.nz> wrote in message
news:I9asd.13581$3U4.297492@news02.tsnz.net...
>> Congratulations! Why?
> Wants to severely compromise gain staging, overload sensitivity, and freq
> linearity.

Yes, but surely there are cheaper ways to do that :-)

TonyP.