cheap pre-amp mod advice - component experts unite!

[crazydoc]

crazydoc, Bob's mods...you guys agree? Is there anything else worth doing?

Looking over this again, I see that Black Lion had resistor swaps and three caps removed. I have to say I didn't go that far, and it already sounds much better. Replace the electrolytic caps and bypass the caps on the input side (C12-15) with .1uf poly films. Swap the opamp for OPA2134. Change the tube if you like, and see where that gets you.

Record something really simple and repeatable, like a few guitar chords, before the change so you can A/B it.

I would echo this - tube (because it's easy), then op amps and then input caps. This should get you the best bang for your buck.

You don't need to worry about bypassing the feedback resistors as the OPA2134 doesn't have the bandwidth of the LM6172 that he used. The spec sheet for the 2134 does however recommend bypassing the power suply pins with 10nF or greater caps. Also, you could put in sockets for the op amps - I don't think any miniscule stray capacitances that might introduce will affect this circuit.

This all makes me wonder if other budget preamps can be modded in simpler ways to improve their sound, do many of these sort of pres have socketed op amps?.... how much difference would upgrading the op amps on units such as the dmp3 and the audio buddy make?

I don't know about modding the Audiobuddy or the DMP3 - thay are pretty clean as is. Naturally enough we're all looking for easy cheap mods to make our stuff sound like a million bucks - unfortunately, in most cases if it were easy or cheap, they would have built it that way in the first place.

But it's fun trying.


It would be a nice project to get this kit from PIAA (Tube Mic Preamp):
http://www.paia.com/tubestuf.htm
http://www.paia.com/fantusch.gif

and then mod it as you build it:
http://www.tapeop.com/magazine/bonus/paiamicpremods.html

 

[amzavareei]

Be careful with the parts ;list on that PDF, there are some errors. Double check the instructions first. I haven't done these mods yet, but was thinking of doing some similar mods to my Levelar, and then some other mods I have planned for my Aphex 107 and Studio Projects VTB-1. I opened up my Digi 001 to see what mods I could do, but I'm just gonna get a 002 anyway. I was gonna replace the SSM2017s with the SSM2019s, and replace some caps. The AD825s are supposed to be really amazing opamps, but they need a bit of modding to drop into NE5532. Here's the URL http://www.tech-diy.com/ad825_adapter.htm for the opamp schematic. The place have the 825s pretty cheap too. I've seen the premade ones somewhere for like 22 bucks somewhere, but making them myself it should run like 5 bucks each. I'll get to all these mods soon enough...

 

[Room 13]

I'd love to try that mod... I'm having trouble finding it online anywhere anymore. Can you post a link? Thank you!

 

[little angel]

I'd love to try that mod, too, but the pdf file link is dead

 

[Steenamaroo]

Welcome to the forums, little angel.

I think you might be out of luck. Most of this thread is from '05, and the only username I recognise isn't active here anymore.

Hopefully someone has subscribed to this thread, but I think google might have to be your friend.

 

[PRHunt]

I don't know about modding the Audiobuddy or the DMP3 - thay are pretty clean as is. Naturally enough we're all looking for easy cheap mods to make our stuff sound like a million bucks - unfortunately, in most cases if it were easy or cheap, they would have built it that way in the first place.

I have modified a DMP3. I replaced the op-amps with Burr Brown OPA2134 (I think they were the duals). The existing op-amps are single inline (SIL) devices, so I needed SIL to DIL adapters which I sourced from Brown Dog.

I replaced most of the small value caps with Vishay film caps, and I replaced signal coupling electrolytics with Nichicons. I also installed larger power supply reservoir caps.

Overall, clean became cleaner, and a bit quieter overall.