Auditronics Upgrades

papercuts · Post by **papercuts** » Tue Feb 07, 2006 11:48 am

Hello, I was wondering if any Auditronics users out there, particularly Joel Hamilton, know of any simple chip upgrades. I have an 18 channel 110a Grandson, which sounds very good but is full of the lm301, which are supposed to be poor quality. Anyone know what would be a good replacement? Thanks,

Jason

joel hamilton · Post by **joel hamilton** » Tue Feb 07, 2006 8:30 pm

Auditronics actually put out a revision, along with a simple schematic for "substituting the 701 for 5534."

It requires a little support circuitry, like one small cap for stability.

Search for that on the web, if you dont find it, I may be able to scan mine for you, PDF style.

You would be amazed at what a bunch of well socketed, burr brown 5534 eqiivalents (opa134? I cant remember) will do for that console, and a complete recap of the entire thing.

I have a different model. the big brother to what you have, and mine is discrete and basically fully custom, but with the inductive coil EQ's (4 band on the 501 module, rather than the 3 that your 110 modules have).

There are five big, nasty, silver electrolytics per channel. If there are ANY of those in your console, throw them out the window immediately. If you can, fire them into outer space....

A full re-cap and re-IC will do WONDERS for that console, especially in the master section.

Gutting the master section completely is what i did.... but i had another auditronics 501 based console that I just re-IC'd and re-capped back in the day and it was the reason i got the one i have now, just for the Eq though basically...

Have fun., Let me know how you make out finding the scem for the upgrades...

Electro-Voice 664 · Post by **Electro-Voice 664** » Wed Feb 08, 2006 7:12 am

jamesfei · Post by **jamesfei** » Wed Feb 08, 2006 10:02 am

Auditronics with LM301's should have a ceramic cap between pins 1 and 8 (20pf or lower). This should be removed if you swap it for a 5534 (as on some later modules) or other chips. As with all chip replacements, watch out for stability. You can do other tweaks like replacing the feedback compensation cap with a COG and lowering its value (again, if stable) for more bandwidth. As mentioned, you'll probably want to replace the signal electrolytics, maybe add a parallel film cap if you're tweaky. The power supply decoupling caps (the electrolytics or tants) can be bigger and better.

Changing the EQ opamp can vary the sound significantly, so there may be a lot of subjective decision making there. It uses inductors but the eq is in the feedback path of the chip.

I think later modules also have a ferrite bead on the output cap of the mic pre (which may hint at stability issues).

Best,

James

papercuts wrote:Hello, I was wondering if any Auditronics users out there, particularly Joel Hamilton, know of any simple chip upgrades. I have an 18 channel 110a Grandson, which sounds very good but is full of the lm301, which are supposed to be poor quality. Anyone know what would be a good replacement? Thanks,

Jason

papercuts · Post by **papercuts** » Wed Feb 08, 2006 3:44 pm

Thank you guys so much for the replies so far. It looks like I have finally tracked down schematics for the board, so I'm sure I will have more questions soon. From what I can find you are right about the Burr Brown opa134 being equivalant to the 5534, does anyone want to confirm that?

Joel, if you ever find your shematic for substituting the opamps that would be great if you couid scan them, I haven't had any luck finding them. And yes, I think recapping is the next step. That said I really like how it sounds now, especially the eq's and the pre's to tape so I'm excited to see what this will do...

Jason

linus · Post by **linus** » Tue Jul 04, 2006 8:46 am

Hey. Reviving this thread because I am getting my Auditronics 110B pair re-racked. I don't have the LM chips in it, I have the 5534s. So I suppose mine was a llater version or maybe someone "upgraded" them at some prior point.

Couple questions:
Is it worth swapping out the 5534s for the Burr Browns mentioned above? Is it a simple switch (pop out the 5534sa. pop in the Burr Browns with no other changes)? Or do other changes need to be made as well for stability?

joel hamilton · Post by **joel hamilton** » Wed Jul 05, 2006 12:51 pm

linus wrote:Hey. Reviving this thread because I am getting my Auditronics 110B pair re-racked. I don't have the LM chips in it, I have the 5534s. So I suppose mine was a llater version or maybe someone "upgraded" them at some prior point.

Couple questions:
Is it worth swapping out the 5534s for the Burr Browns mentioned above? Is it a simple switch (pop out the 5534sa. pop in the Burr Browns with no other changes)? Or do other changes need to be made as well for stability?

You may get lucky without any support circuitry. I did. before doing the discrete mods on myine, I did all burr brown, and really nice caps everywhere. I also got rid of all the tantalums on the damn power rails, as they short to ground. I USE the thing every day, and I dont do much work on it myself, as I am lucky to have an amazin tech source at purple audio. Those men are amazing. Seriously amazing. Beyond just "tech" and more like wizard...

The BB's certainly helped the "getting pushed hard" character of the console, and I REALLY liked the change in the mic pre. If your modules have shitty sockets for the IC's (or none at all) put some in with gold contacts, and it really helps as well.

linus · Post by **linus** » Wed Jul 05, 2006 8:11 pm

joel hamilton wrote: You may get lucky without any support circuitry. I did. before doing the discrete mods on mine...
...purple audio. Those men are amazing. Seriously amazing. Beyond just "tech" and more like wizard...

The BB's certainly helped the "getting pushed hard" character of the console, and I REALLY liked the change in the mic pre. If your modules have shitty sockets for the IC's (or none at all) put some in with gold contacts, and it really helps as well.

Joel, I hadn't even considered the fully discrete route. I wonder if the Purple Audio discrete card / daughter cards are an option...

alan901 · Post by **alan901** » Sat Aug 20, 2011 5:58 pm

Sorry for bumping an ancient thread, but I can't seem to find the Auditronics 501 Mic Pre/EQ schematic anywhere online.

Any help on the schematic and info on support circuitry for IC upgrades would be greatly appreciated.

joel hamilton · Post by **joel hamilton** » Sat Sep 10, 2011 5:33 pm

alan901 wrote:Sorry for bumping an ancient thread, but I can't seem to find the Auditronics 501 Mic Pre/EQ schematic anywhere online.

Any help on the schematic and info on support circuitry for IC upgrades would be greatly appreciated.

My hot rodded auditronics went to the Bunker. You should email them. I gave them some pretty thorough documentation.

Jim Williams · Post by **Jim Williams** » Sun Sep 11, 2011 7:29 am

The last set I went through I pulled out the local .1 uf psu bypass caps and fitted 220 uf/25v El caps awith .1 mono's mounted underneath. I used polyprop film and foil Wima caps in the EQ and mounted machine sockets for the opamps. I used ADA4898-1/LME49710NA and yanked out the el signal coupling caps. BB OPA1611 is another good choice.

It went from DC to 200k hz, no phase shift, very little noise and THD.

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