Presonus Eureka Mod

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seveone

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So, it seems alot of people that own the MP20 and M80 switch out the Opamps and transformers. Is this a mod that can be done to a Eureka? Will it make a difference?

I can't find any info about the stock opamps, and I just got the eureka yesterday. It sounds alright, but I was in a crunch and needed something better than my board (it is...much), and it was reviewed better than average. Got it over a Focusrite TwinTrak, ART Pro Channel and a couple other mid priced pre's. I'm just "test driving" and can return it, but for what it has to offer, and if a opamp mod would make a difference I'll keep it. My other options are to return it, get a Toft Audio EC-1, FMR RNP, Tampa, Grace 101 (and a RNC), or a Presonus MP20 and mod it.

My price range is $400-600 (total). I'm only doing a project/home thing now, possibly upgrade later but I only record for a couple bands now (mine and a couple friends), and mixing/mastering. I'd like to be able to keep and use whatever I get, down the road as a backup if I further this "studio".

Any advise?
 
seveone said:
So, it seems alot of people that own the MP20 and M80 switch out the Opamps and transformers. Is this a mod that can be done to a Eureka? Will it make a difference?

I can't find any info about the stock opamps, and I just got the eureka yesterday. It sounds alright, but I was in a crunch and needed something better than my board (it is...much), and it was reviewed better than average. Got it over a Focusrite TwinTrak, ART Pro Channel and a couple other mid priced pre's. I'm just "test driving" and can return it, but for what it has to offer, and if a opamp mod would make a difference I'll keep it. My other options are to return it, get a Toft Audio EC-1, FMR RNP, Tampa, Grace 101 (and a RNC), or a Presonus MP20 and mod it.

My price range is $400-600 (total). I'm only doing a project/home thing now, possibly upgrade later but I only record for a couple bands now (mine and a couple friends), and mixing/mastering. I'd like to be able to keep and use whatever I get, down the road as a backup if I further this "studio".

Any advise?
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Open it up and post a close-up picture of the opamps and also the input caps if you can get to them.
 
The Presonus Eureka isn't a bad little strip, I like the input ohm selection on the pre too.

War
 
Alright, took the top off and what I get is (2) NE5534AP - so these are the 5534's huh? They appear to be simple enough, no soldering. Big silver thing? No writing. Above both 5534's is a op07c. On each side of the 5534s - not sure - 45/10/50v. The image is poor, but hope it helps decipher.
 

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seveone said:
Alright, took the top off and what I get is (2) NE5534AP - so these are the 5534's huh? They appear to be simple enough, no soldering. Big silver thing? No writing. Above both 5534's is a op07c. On each side of the 5534s - not sure - 45/10/50v. The image is poor, but hope it helps decipher.
Click to expand...

Yep that looks pretty similar to the MP20/M80, with socketed 5534s. You can try OPA134, OPA627. I haven't tested the 627, but I believe others have without it oscillating. There are a few Analog Devices opamps that get recommended too, but I don't know the part #s--AD797? Maybe somebody else will.

OP07 is another opamp, looks like it's surface mount in your photo. Not sure what it's doing, but I think Presonus' design was to socket the key opamps so they'd be easy to swap. Pretty cool if you ask me :cool:

Since it looks so much like the MP20, it might be too hard to get to the input caps to make a swap worthwhile. I didn't bother with the MP20 or the M80, because too much disassembly was required. I haven't read about anybody else doing cap swaps either.

The silver thing is the transformer. All the weensy bits around the opamps are little surface mount resistors, might be a few caps there too, I don't recall. Don't worry about 'em. There will also be more opamps in the compressor and EQ section, but I don't know anything about those circuits.

Back to the opamp swap, I used OPA134 which is better, not dramatically so, but incrementally. Still it's so easy that I recommend doing it. The OPA627 mod owners seem pretty happy too.
 
OPA134AP $2.25
OPA627AP $18.00

Are they that much better @ 18.00? Not concerned with the price as much as the price difference. Why so much more?

I should get the ones (either version) that end in AP right?
 
seveone said:
OPA134AP $2.25
OPA627AP $18.00

Are they that much better @ 18.00? Not concerned with the price as much as the price difference. Why so much more?
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627 is a superfast opamp, with a corresponding price. 134 is faster than the 5534, quieter too, but it doesn't have the speed of the 627.

TI has a sample program where you can get a few opamps, check their website.

I should get the ones (either version) that end in AP right?
Click to expand...

Yes.
 
Look into past issues of TapeOp, they had an article where the dude 'hot wired' his eureka. That may help. I think the wife threw my copy away. :(
 
Ok, I ordered (2) OPA134PA, (2) OPA627AP, and (2) OPA637AP from Ti, as free samples and they overnight for free too. Pretty good deal. I'll post back when I get them and sample them. I'll try to post samples of them too.

Thanks for the help.
 
seveone said:
Ok, I ordered (2) OPA134PA, (2) OPA627AP, and (2) OPA637AP from Ti, as free samples and they overnight for free too. Pretty good deal. I'll post back when I get them and sample them. I'll try to post samples of them too.

Thanks for the help.
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You might have trouble with 637, it isn't unity gain stable. But if it doesn't work, just yank it out & pop in one of the other ones.
 
Got the new chips yesterday (UPS Overnight AM Delivery - FOR FREE). Install took all of 3 min. I recorded 3 bass tracks: one straight from the board (mackie) E/Q'ed from the board and a Composer Pro XL for compression into a MOTU 828MkII, one through the Eureka with the original chips proccessed with the built in Comp and EQ direct to the MOTU, then one with the Eureka with switched out the Opamps (OPA627AP), same setup to the MOTU.

WOW.

The board was muddy, not really any dynamics, not horrible, but not happy either.

The Eureka with the originals, was like night and day over the board without even A/B'ing. Sounded really good, but a little muddy in the lows, and highs we're a bit muddy mid sounding. THe mids were good though.

Now, The Eureka with the mods chips (OPA627AP), didn't seem at first like a night and day difference. Until, I A/B'ed the two Eurekas. HUGE difference. The low end is really well rounded and not muddy at all. The mids seemed clearer, but not OMG! clearer. The highs poped out as much as the low end, really clear. overall much more clear and punchy. The EQ and Comp really work that clear signal. Almost as big of a difference as A/B'ing the board to the original Eureka.

Overall this experience was painless - AND FREE. I'm not an electronics know-it-all. Really pretty ignorant. But I know how to change out chips. Just like upgrading a proccesor, or swithing RAM, just smaller. If anybody is interested in doing this, Texas Instruments sent 2 samples of each OPAMP that I wanted, overnight, early morning delivery - FOR FREE. Can't beat that. I almost paid $18.46 a piece plus delivery just on the OPA627AP's. And based on my results, I would have been very happy doing that.

It'll be a little while before I post samples. I'm not a bass player, and nobody needs to hear my voice. In a couple weeks I'll have something.

Thanks for the help mshilarious!

7
 
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seveone said:
Thanks for the help mshilarious!
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No problem. Those were pretty much my reactions too, definitely noticed the tightening up of the low-end. I don't remember a big high-end change, but I usually test mods with a guitar and bass DI, so there isn't a lot of high frequency content to test.
 
seveone said:
It'll be a little while before I post samples. I'm not a bass player, and nobody needs to hear my voice. In a couple weeks I'll have something.
Click to expand...

Thanks, keep us posted.
 
upgrading too!...

I've been very pleased with my Eureka with the stock op amps, but (thanks to this thread) I also requested Burr-Brown samples from TI which arrived very promptly...I also scored an MP20 (real clean vintage 1999, with the original Jensen transformers) for only $199. on Instrumentexchange.com just a few days ago, so I'll be doing the B-B upgrades (I have samples of both the recommended op amps) on the 2 preamps...I'm anxious to hear the improvements...my Rane MSB1 has the B-B ops and it's very clean sounding...
Thanks to everyone who chimed in on this thread! (especially mshilarious!)...this is a great example of the productive and educational value of the HR.com site...
 
deepwater said:
Anyone know how to MOD a M-Audio Tampa?
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First off you need to ascertain if it's surface mount, and whether or not you can do surface mount work.

If you get too deep into modding, the best place to hang out is the Lab:

http://www.prodigy-pro.com/forum

I didn't find any Tampa threads there, but if you post a thread with pictures and/or a schematic, somebody will take a crack at it. Heck, they've even kicked around modding Nady stuff.
 
Thanks...

Nady??? You know times are hard when you start trying to make NADY sound better :)
 
deepwater said:
Thanks...

Nady??? You know times are hard when you start trying to make NADY sound better :)
Click to expand...

The box in question I think was 8 preamps in a 1u box for $100. I think they threw out everything but the box, the connectors, and the power supply :D
 
kidvybes said:
I've been very pleased with my Eureka with the stock op amps, but (thanks to this thread) I also requested Burr-Brown samples from TI which arrived very promptly...I also scored an MP20 (real clean vintage 1999, with the original Jensen transformers) for only $199. on Instrumentexchange.com just a few days ago, so I'll be doing the B-B upgrades (I have samples of both the recommended op amps) on the 2 preamps...I'm anxious to hear the improvements...my Rane MSB1 has the B-B ops and it's very clean sounding...
Thanks to everyone who chimed in on this thread! (especially mshilarious!)...this is a great example of the productive and educational value of the HR.com site...
Click to expand...

yes, this is a real thread..free stuff!!
I noticed Presunus Eureka made one of the Top picks for 2004- EM.
Any comparison to the DMP3/RNC?? better, worse...no change??
 
Does anyone know if the following are the right opamps for the Eureka?

Samples Ordered:
LT1357CN8#PBF
LT1357CS8
LT1357CS8#PBF

Anyone got any of those Brown burrs around they want to get rid of? I will pay the postage:-)
 
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