RIAA / Pre mod/upgrade

Cobra2 · 25th July 2007, 02:12 PM

Hi! I have this RIAA, (from far-east), that is fairly unusable...sounds like it is far off the curve....and no good overall sound...
Please give me some suggestions on how to upgrade, and calculate the riaa-filter...
Maybe go for other tube-types too?

Arne K

RIAA;

Cobra2 · 25th July 2007, 02:13 PM

Arne K

PRE;

Cobra2 · 31st October 2007, 05:55 PM

I found this: http://www.beigebag.com/case_riaa_3.htm

Arne K

KaDe · 31st October 2007, 10:02 PM

Series feedback is the most insufficient way to achieve RIAA and will always sound strange.
You may try parallel feedback like in this design:

Conta · 3rd November 2007, 06:57 PM

I think with two stages and negative feedback you have too small sensitivity of RIAA corrector to reach standard output level 1Vrms. Try circuit with 3 stages and without negative feedback, like this: http://audio.ring.lt/pre/pre_en.html

Cobra2 · 3rd November 2007, 07:15 PM

6N16... do not have that tube... closest replacement?

Arne K

Conta · 3rd November 2007, 07:46 PM

You can try not pencil tubes ECC84 (6N14P)

KaDe · 3rd November 2007, 07:58 PM

Hi !

Passiv RIAA is a good idea, here is a simple two stage design:

bucurb · 3rd November 2007, 07:58 PM

KaDe,

What could be B+ value in your phono schematic, please? Thanks.

KaDe · 3rd November 2007, 08:15 PM

The parallel feedback circuit needs something around 320V B+
The passiv RIAA just posted works at 250V B+

31st October 2007, 05:55 PM	#3
Cobra2 DIY ! diyAudio Member Join Date: Apr 2002 Location: Stavanger, Norway	riaa-filter calc (active) I found this: http://www.beigebag.com/case_riaa_3.htm Arne K __________________ Ars longa, vita brevis

3rd November 2007, 07:15 PM	#6
Cobra2 DIY ! diyAudio Member Join Date: Apr 2002 Location: Stavanger, Norway	6N16... do not have that tube... closest replacement? Arne K __________________ Ars longa, vita brevis

3rd November 2007, 07:58 PM	#9
bucurb diyAudio Member Join Date: Sep 2004 Location: Bucharest	nice schematic KaDe, What could be B+ value in your phono schematic, please? Thanks.

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3rd November 2007, 06:57 PM	#5
Conta diyAudio Member Join Date: Aug 2007	I think with two stages and negative feedback you have too small sensitivity of RIAA corrector to reach standard output level 1Vrms. Try circuit with 3 stages and without negative feedback, like this: http://audio.ring.lt/pre/pre_en.html

3rd November 2007, 07:46 PM	#7
Conta diyAudio Member Join Date: Aug 2007	You can try not pencil tubes ECC84 (6N14P)

3rd November 2007, 08:15 PM	#10
KaDe diyAudio Member Join Date: May 2007	The parallel feedback circuit needs something around 320V B+ The passiv RIAA just posted works at 250V B+

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