[sdiy] DIP LM13700 discontinuation

cheater cheater cheater00social at gmail.com
Thu May 27 06:57:55 CEST 2021


Yes, as I understand the filters are something you should build
yourself and attach to the front end.

On Wed, May 26, 2021 at 7:52 PM Mike Bryant <mbryant at futurehorizons.com> wrote:
>
> The open loop gain of an op-amp will make no difference to the stereo levels - that is purely down to the accuracy of the gain setting resistors.
>
> And the signal has already been through at least two to three dozen op-amps in series getting to you.  A few more are going to make very little difference.
>
> And whilst a good instrument, a Levell TM3B is not going to accurately measure the -128dbu noise output of a mic amp.  It doesn't have the correct filters to start with.
>
>
> -----Original Message-----
> From: cheater cheater [mailto:cheater00social at gmail.com]
> Sent: 26 May 2021 18:46
> To: Mike Bryant
> Cc: Benjamin Tremblay; synth-diy at synth-diy.org
> Subject: Re: [sdiy] DIP LM13700 discontinuation
>
> On Wed, May 26, 2021 at 5:02 PM Mike Bryant <mbryant at futurehorizons.com> wrote:
> >
> > The TL07x is just a selected TL08x, mostly for gain, which translates to better offset voltage and sometimes slightly better noise.
> > Can you measure the difference ?  Just about
> > Can you hear the difference ?   Except in a mic amp, probably no chance, and even then probably only with an AP to convince you the noise is 1dB more above the theoretical noise floor.  It's only when you get into something like a 40 channel mixer that all these noises start adding up to something annoying.
>
> It can easily matter when doing stereo. 1dB of difference can shift the stereo field.
> It can easily matter in a thing that uses many op amps in series. Like a filter or a crossover.
> You don't need an AP unit to measure low noise. You can use a Levell TM3B, which goes real cheap, plus possibly a J-Can LNA (diy) if necessary.
>
> The Levell TM3B has super low self noise and input capacitance and the right bandwidth for an audio meter.
>
> J-Can: http://physicsopenlab.org/wp-content/uploads/2016/10/JCan-NV-article.pdf
>
>
> > -----Original Message-----
> > From: Synth-diy [mailto:synth-diy-bounces at synth-diy.org] On Behalf Of
> > Benjamin Tremblay via Synth-diy
> > Sent: 26 May 2021 15:48
> > To: Michael E Caloroso
> > Cc: synth-diy at synth-diy.org
> > Subject: Re: [sdiy] DIP LM13700 discontinuation
> >
> > Okay, I will go off on a tangent in this near-dead thread.
> >
> > When I was a kid, I could only get the TL08 series op amps at Radio Shack. I see you audio people like the TL07s better, so I went and bought a tube of TL071, TL072, and TL074.
> > But I’m still going through my stock of TL084s.
> >
> > When would be a case where I pull the TL08 from its socket and replace it with a TL07? What am I getting?
> >
> > Thanks,
> >
> > Ben
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