freaky new phonostage

[dave slagle]

Hey John,

not thomas but he did help me with this a number of years ago. Essentially you need to add an additional resistor (R25) above the .126u 68K combo and lower the value of the 45mhy inductor.

dave

[mashaffer]

Originally Posted by Vinylsavor

Hi!



A while back I shared a design of a full function preamp with RC RIAA phonosection on AA. I call it the Octal preamp. It uses 6SL7/6N7/6SN7 tubes.
If there is interest, I'll open a thread about it and post the schematics

Best regards

Thomas

Thanks, I am always interested in seeing stuff like this. I had gotten it in my head that I wanted to try one using the 12A_7 series of tubes just for giggles. I can't find the latest version of the schematic right off hand but it is essentially like this with a 12AY7 instead of 12AT7 for the lower element of the mu-follower.

[revintage]

Hey guys,
This an example of compensation that I simmed. The filters are from a Neumann 1974 cutter. It will still be approximation as Neumanns is 2nd order. If you have Daves chokes, Lundahls or a EQ-2L you can adopt it. The blue is uncompensated.

[dave slagle]

hey lars,

surely a few value tweaks can fix the minor drop at 5-6khz. In some circles that -0.2dB would surely make the results unacceptable :-)

dave

[Wavebourn]

You can borrow my test signal (please return it after you done!):

http://wavebourn.com/gallery/riaa/Re...Sweep-RIAA.wav

[revintage]

Hey Dave,
You can stay well below 0,1dB with 45mH, this has been showed at your place. What I now showed was an example of the difference between Neumann and std. Will surely be aproblem to do it IRL due to component-tolerances.

Below is another sim that shows the differences between std and Neumann. The *.asc is also in a thread at your place. Blue is Neumann-corrected. Now check tolerance .