solid state DC class-A RIAA schematic needed

[neazoi]

hello,
Is there any schematic out there for a direct coupled class-A RIAA preamplifier? Better to be a capacitor-less circuit...

I have seen this pre-pre preamplifier of the 80s but this is a pre-preamplifier for MC cartridges, to bring them in MM level, not a RIAA one...

[neazoi]

Here is the pre-pre

[AndrewT]

Hi,
the RIAA characteristic cannot be obtained without capacitors.

The RIAA also has two standards for Bass roll off. Both require a DC blocking cap in the signal route to achieve that.

A DC coupled capacitorless RIAA cannot comply with RIAA standard.

[neazoi]

Thank you Andrew!
I have also seen this design of hiraga. It uses 1-2 caps only, but unfortunately the article is in French so I cannot understand the details. It says something like this achiever the RIAA response using passive method...?

I have not seen another similar circuit thought...

[alayn91]

Hello,

Here are the details translated, at my best:

Direct coupled transistorized pre-amplifier as decribed in november 85 japonese "Stereo music" revue.
Input stages are symmetrical & differential cascodes and are followed by drivers stages and push-pull output with MOSFET.
Between the linear stages wich gains are respectively 33,6dB & 27,2dB,
the passive RIAA correction takes place with passive components LCR Tango EQ-600P.
Total gain is about 41dB, the average distorsion ratio is 0,002%, between 10Hz & more than 40kHz.
Global harmonic distorsion don't reach 0,002%.

Et voila.

Some infos I found about Tango EQ-600P:
http://digilander.libero.it/paeng/inductive_riaa.htm
And, others with Google !

Regards.
Alain, from France.

[knutn]

You may try my oldie: RIAA Amplifier

[DF96]

To do RIAA without capacitors means either using inductors (with perhaps greater problems) or some form of digital processing. You might also need perfect records played on a perfect turntable, as you would have no protection against warps and arm-cartridge resonance. You would need battery supplies, as you can't smooth the mains without capacitors.

Why?

[neazoi]

Alayn, so it uses an interstage transformer to do the equalization, I got this now, thanks a lot for the translation.

Knuth, It seems an interesting design, does it operate in class-A (I bet so)? Could it be used for high fidelity or is it just for old 60s phono heads? A listening impression would help.

[neazoi]

Originally Posted by DF96

To do RIAA without capacitors means either using inductors (with perhaps greater problems) or some form of digital processing. You might also need perfect records played on a perfect turntable, as you would have no protection against warps and arm-cartridge resonance. You would need battery supplies, as you can't smooth the mains without capacitors.

Why?

Df, I mean no caps on the signal path. And yes my Le monstre amplifier operates on batteries only
I am trying to use high quality components and simple designs to achieve best transparency. And DC mostly offers the best transparency. In some cases DC cannot be done, that is why I have started this thread

[knutn]

Originally Posted by neazoi

Knutn, It seems an interesting design, does it operate in class-A (I bet so)? Could it be used for high fidelity or is it just for old 60s phono heads? A listening impression would help.

Yes it is operated in Class A; it was used with my high output MC (about 3.5 mV) for high fidelity listening. But it deserves a better power supply. And yes, it sounded good...