Dead bug RIAA Pre

jackinnj · 6th December 2009, 07:40 PM

Took the opportunity of yesterday's crummy weather to dead-bug a passive RIAA pre using the LM4562 -- I got out the old RLC bridge and went through the component bin to get close to exact values for the network:

ikoflexer · 6th December 2009, 07:47 PM

Love the construction! It hardly can get more real than this

Looking forward to the rest of the story.

jackinnj · 08:54 PM

Here's a first shot at the performance:

I'm using Walt Jung's values from "The Op Amp Applications Handbook".

jackinnj · 7th December 2009, 02:54 PM

THD+N @2kHz is about 0.01%.

Glowbug · 7th December 2009, 05:40 PM

Cool

Rodeodave · 7th December 2009, 08:50 PM

Awesome! I'm really a fan of p2p, but I have to confess that I never built a true dead-bug design with a ground plane and such. Definitely up next!

Capt Zach · 8th December 2009, 04:23 PM

Nice job. I've also been eyeing this circuit, but haven't gotten around to ordering the parts yet. Have you gotten a chance to listen? I cant tell from the pic, did you build the full dc coupled circuit? I was thinking of omitting the low pass on the output

jackinnj · 8th December 2009, 04:48 PM

Quote:

Originally Posted by Capt Zach

Nice job. I've also been eyeing this circuit, but haven't gotten around to ordering the parts yet. Have you gotten a chance to listen? I cant tell from the pic, did you build the full dc coupled circuit? I was thinking of omitting the low pass on the output

No, I didn't put in the servo -- yet -- and it is DC coupled. The AD745 is a shown on Walt's schematic is a BiFET opamp and the LM4562 isn't so some belts and suspenders will probably be needed. I will probably have to get the Dremel out and put the servo on the bottom!

Dead-bug on copper is great because you have the ground plane, you have a heat sink and the P2P means that there aren't little gremlins running around on the fiberglas. The easiest way to nail down the opamps is with the ceramic bypass caps on pins 4 and 7.

jackinnj · 8th December 2009, 05:51 PM

Put a little LPF on the tail -- it could be tweaked a bit -- but this should tame clicks and pops:

6th December 2009, 07:40 PM	#1
jackinnj diyAudio Member Join Date: Apr 2002 Location: Llanddewi Brefi, NJ	Dead bug RIAA Pre Took the opportunity of yesterday's crummy weather to dead-bug a passive RIAA pre using the LM4562 -- I got out the old RLC bridge and went through the component bin to get close to exact values for the network:

6th December 2009, 08:53 PM	#3
jackinnj diyAudio Member Join Date: Apr 2002 Location: Llanddewi Brefi, NJ	Here's a first shot at the performance: I'm using Walt Jung's values from "The Op Amp Applications Handbook". Last edited by jackinnj; 6th December 2009 at 08:54 PM. Reason: more information

7th December 2009, 05:40 PM	#5
Glowbug diyAudio Member Join Date: Feb 2006 Location: Hillsborough, NC/McLean, VA	Cool __________________ Jim J.

7th December 2009, 08:50 PM	#6
Rodeodave diyAudio Member Join Date: Dec 2004 Location: in the alps Blog Entries: 1	Awesome! I'm really a fan of p2p, but I have to confess that I never built a true dead-bug design with a ground plane and such. Definitely up next! __________________ Gravity - Making the G since 13.7 billion B.C.

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6th December 2009, 07:47 PM	#2
ikoflexer diyAudio Moderator Join Date: May 2008 Location: Toronto	Love the construction! It hardly can get more real than this Looking forward to the rest of the story.

7th December 2009, 02:54 PM	#4
jackinnj diyAudio Member Join Date: Apr 2002 Location: Llanddewi Brefi, NJ	THD+N @2kHz is about 0.01%.

8th December 2009, 04:23 PM	#7
Capt Zach diyAudio Member Join Date: Jun 2004 Location: VA	Nice job. I've also been eyeing this circuit, but haven't gotten around to ordering the parts yet. Have you gotten a chance to listen? I cant tell from the pic, did you build the full dc coupled circuit? I was thinking of omitting the low pass on the output

8th December 2009, 05:51 PM	#9
jackinnj diyAudio Member Join Date: Apr 2002 Location: Llanddewi Brefi, NJ	Put a little LPF on the tail -- it could be tweaked a bit -- but this should tame clicks and pops:

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