Circuit toplogy considerations for RIAA............

Chris · 22nd September 2001, 04:05 PM

Hello again !!!

A few weeks ago I posted a thread in the general forum, about RIAA designs. I got alot of good feedaback from the members. Thank you !!

So far I have decided to use two BB OPA606 opamps with a passive network for the 2122 Hz rolloff, and a filter for the 50 and the 500 Hz brakepoints in the feedback circuit of the first opamp.
This procedure is described in the following article:

http://www.national.com/an/AN/AN-346.pdf

Thanks to PaulB for providing me (and others) with this information.

Now the question:
Since I`m making pcb`s for this project I wondered if some of you have any ideas how to get the best result.
Placing of compnents so they won`t distort the signal etc. ?
Using double sided pcb`s with ground and compnents on one side and both signal and power traces on the other?
Or power traces on one side and the signal path on the other side?

Thanks in advance!!

Chris.

alaskanaudio · 27th October 2001, 05:52 PM

A very fine RIAA Pre-Amp design utilizing a active EQ stage is available on my web site. It utilizes the Burr Brown OPA2134 for the flat input stage and/or OPA2134 or OPA2604 for the EQ and output stages. The noise floor is very low due to parralleling eight OPA2134 devices on the input stage. Sound quality is truly excellent. Circuit boards with on board voltage regulators are available.

The link to information on this preamp is:

http://www.audioamps.com/diyparts/pcb/pcb.htm

John Fassotte
Alaskan Audio

P.Lacombe · 27th October 2001, 07:12 PM

Chris,

There is a problem with the NS design : the electrolytic condenser Co in the feedback network of the first Op Amp.
Extended listening tests have proved that such design exhibit medium sound quality, because of the abnormal behavior of electrolytics at audio frequencies (erratic non-linearities).

Regards, P.Lacombe.

27th October 2001, 05:52 PM	#2
alaskanaudio diyAudio Member Join Date: Sep 2001 Location: Fairbanks, Alaska	RIAA Pre_Amp Project A very fine RIAA Pre-Amp design utilizing a active EQ stage is available on my web site. It utilizes the Burr Brown OPA2134 for the flat input stage and/or OPA2134 or OPA2604 for the EQ and output stages. The noise floor is very low due to parralleling eight OPA2134 devices on the input stage. Sound quality is truly excellent. Circuit boards with on board voltage regulators are available. The link to information on this preamp is: http://www.audioamps.com/diyparts/pcb/pcb.htm John Fassotte Alaskan Audio

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22nd September 2001, 04:05 PM	#1
Chris diyAudio Member Join Date: Sep 2001 Location: NORWAY	Hello again !!! A few weeks ago I posted a thread in the general forum, about RIAA designs. I got alot of good feedaback from the members. Thank you !! So far I have decided to use two BB OPA606 opamps with a passive network for the 2122 Hz rolloff, and a filter for the 50 and the 500 Hz brakepoints in the feedback circuit of the first opamp. This procedure is described in the following article: http://www.national.com/an/AN/AN-346.pdf Thanks to PaulB for providing me (and others) with this information. Now the question: Since I`m making pcb`s for this project I wondered if some of you have any ideas how to get the best result. Placing of compnents so they won`t distort the signal etc. ? Using double sided pcb`s with ground and compnents on one side and both signal and power traces on the other? Or power traces on one side and the signal path on the other side? Thanks in advance!! Chris.

27th October 2001, 07:12 PM	#3
P.Lacombe diyAudio Member Join Date: Jul 2001 Location: Orleans, France	Chris, There is a problem with the NS design : the electrolytic condenser Co in the feedback network of the first Op Amp. Extended listening tests have proved that such design exhibit medium sound quality, because of the abnormal behavior of electrolytics at audio frequencies (erratic non-linearities). Regards, P.Lacombe.