freaky new phonostage

[nicoch58]

like this

 

[artosalo]

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

Please do this. Phono stages are allways interested to discuss about.
I have also done some.

 

[revintage]

Hey Thomas,
Noticed you use the old std Tango component-values for+/-0,2dB. Do you have an opinion about the so called Neumann or 4th time-constant?
This have been discussed intensively at IntactAudio´s forum.

 

[Zen Mod]

Thomas ;

have you , by any possibility , values of 10K LRC network , discussed on , now defunct, ANSA forum ?

btw .... this one looks Fugly!

 

[Vinylsavor]

Hi Lars,

Do you have an opinion about the so called Neumann or 4th time-constant?

I do implement it when possible. If I use fixed LCR modlues like the Tango EQ600, there is no chance to implement it. I did implement it in the Octal Preamp (see new thread) and also in a LCR linestage using the 6AM4 triode and discrete LCR networks with coils from Dave Salgle of intactaudio.

Best regards

Thomas

 

[Vinylsavor]

Hi!

have you , by any possibility , values of 10K LRC network , discussed on , now defunct, ANSA forum ?

I've never implemented a high impedance LCR network. I prefer low impedance intercaces between stages anyways, so I had no need for it. 10k LCR values can be calculated easily. My concern would be the high inductance values needed. I'm sure Dave can help you with those (intactaudio.com)

Best regards

Thomas

 

[Vinylsavor]

Hi!

btw .... this one looks Fugly!

I got tired of that construction style myself and changed gears, especially since I went commercial some 2 years ago.

ImageShack® - Online Photo and Video Hosting

Do you like this one better ?
That's my big phono and line stage combo, both with external PSUs, phono with EC8020 and linestage with 801A/10Y

Best regards

Thomas

 

[Zen Mod]

this one is great :

Imageshack - phonoline8.jpg

 

[JLH]

Hi Lars,



I do implement it when possible. If I use fixed LCR modlues like the Tango EQ600, there is no chance to implement it. I did implement it in the Octal Preamp (see new thread) and also in a LCR linestage using the 6AM4 triode and discrete LCR networks with coils from Dave Salgle of intactaudio.

Best regards

Thomas

Thomas,

That does the schematic of the discrete LCR with the Neumann constant look like? What extra components are added? Thanks.

 

[nicoch58]

my prefered

 

[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]

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/Reverse-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 .