MP20 mods

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wesley tanner

wesley tanner

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hey all

so I have already modded the OPAMPS in my MP20 from stock to the 627's (I was told there are the burr brown's everyone raves about). it's certainly a damn clean mic pre, at least to my ears...

the ease of this mod has prompted me to want to do more! I know you can switch out the transformer to a jensen one that is supposed to be a lot better as well. how difficult/expensive is this mod? any others that I could do to it? Anyone like any other OPAMPS more than the ones i already have? thanks in advance.

wes
 
wesley tanner said:
hey all

so I have already modded the OPAMPS in my MP20 from stock to the 627's (I was told there are the burr brown's everyone raves about). it's certainly a damn clean mic pre, at least to my ears...

the ease of this mod has prompted me to want to do more! I know you can switch out the transformer to a jensen one that is supposed to be a lot better as well. how difficult/expensive is this mod?
Click to expand...

It's difficult and expensive, and I haven't read that it makes a big difference.

You have to remove the main circuit board, desolder eight leads on the old trannies, then swap them out and swap the Jensens in, and resolder.

I recall the Jensens are about $60 each, and you need two of them.
 
How bout the mod on the MP20 to make it an M80? Or did i not read this post quite right? ;)

Sure, you'd have to add four channel strips, but that's not that much hardware, right?
 
NeoMagick said:
How bout the mod on the MP20 to make it an M80? Or did i not read this post quite right? ;)

Sure, you'd have to add four channel strips, but that's not that much hardware, right?
Click to expand...

Heh. No, I sold the MP20 and bought a M80--that's eight channels, or six more than the MP20.

Ain't no way you can fit six more channels in the MP20 box. The M80 is 2u with an external power supply. Transformers take up a good bit of space.
 
ha. look at that... 8 not 6.

it was funnier when i'd just woken up.
 
I currently own the eureka, and have made the Burr brown mod myself, with nice results I might add. I also came across a web site that had audio clips of the jensen transformer, and the presonus custom transformer using the 5534 chips (I think that's the number of the opamps they ship with?) I noticed a very audiable difference in "warmth" between the transformers, and found that each was good for a different sound. I have since decided to sell my Eureka and get the MP 20 for the same price (hopefully a little less so I can buy a RNC comp.)

Now here is the cool part. :) On one side of the MP 20 I'm adding the Jensen mod with the burr brown chips, and on the other side I'm leaving the custom transformer and using Linear Technology's 1357 opamp chips for a super clean sound. That way I have the choice between a little "warmth" or a more "transparent" sound. Hope that helps.
 
owen_vallis said:
Now here is the cool part. :) On one side of the MP 20 I'm adding the Jensen mod with the burr brown chips, and on the other side I'm leaving the custom transformer and using Linear Technology's 1357 opamp chips for a super clean sound. That way I have the choice between a little "warmth" or a more "transparent" sound. Hope that helps.
Click to expand...

That could be interesting. You will lose the use of the pre for critical stereo micing though.
 
I upgraded my MP20 with the Jensen transformers for a modest cost of $85. Jensen has a special pricing for the JT-11K8-APC transformers at $30 each (versus $47 apiece) for Presonus MP owners. I asked about the installaltion and Jensen said they could do the swapout and bench test for a flat $25. The turn-around time was just one day. That was the best $25 I spent. The people at Jensen are super nice and realy helpful. I highly recommend them for the transformer swapout.

After the transformer upgrade the sound was a little more richer but not as full as i hoped. The stock 5534 opamps were clean but didn't have the fullness that I was looking for.

Then I started to replace the 5534 with the BurrBrown (BB) OPA627A and that's when the sound just kicked ass. The sound was more much fully and richer than the 5534 and stock transformer. I also have a set of Analog Devices ADA797 for the big huge sound with a lot more bass but right now I am pretty happy with the BB OP627A.

Overall I think the MP20 is a pretty cool preamp especially when you have several upgrade paths available with the Jensen input transformer along with the BB OP627A and/or ADA797 opamps.

Pete
 
Has anyone tried a transformer other than a jensen? Could a cinemag or lundahl make a more drastic difference than a jensen? I have heard Jensen xformers described as neutral quite often...
 
I am surrprised you could swap out the 5534"s for the 627"s because they have different Pin configurations and the 5534 is a Quad Opamp and the 627 is a Difet which should not be Compatible at all unless you somehow had a Kit of some sort that reconfigured the Pin layout and if only one channel of the 5534 is being used in the Original curcuit......

I rescently swapped out the Opamps in my Guitar amp for some Burr Brown OPA2107"s and got a Much nicer and warmer sound and a much crunchier Gain sound.....

I am building a Preamp right now that uses the NE5532 Opamps and I am thinking of trying it with some Burr Brown"s that i have to see if it Makes a Positive differance in the sound but from what I hear useing the Stock 5532"s produces a very clean and Uncolored sound.....

Cheers
 
Minion said:
I am surrprised you could swap out the 5534"s for the 627"s because they have different Pin configurations and the 5534 is a Quad Opamp and the 627 is a Difet which should not be Compatible at all unless you somehow had a Kit of some sort that reconfigured the Pin layout and if only one channel of the 5534 is being used in the Original curcuit......
Click to expand...

No, 5534 is single channel. The usual BB upgrades are OPA134 or OPA627. The MP20 is happy with the swap to a FET. Often that is OK; going from FET to bipolar is the issue.
 
riantide said:
Has anyone tried a transformer other than a jensen? Could a cinemag or lundahl make a more drastic difference than a jensen? I have heard Jensen xformers described as neutral quite often...
Click to expand...

I don't know; the Jensen is used because Presonus originally shipped the units with Jensens, then changed to an unbranded tranny that is essentially the same as the original Jensen. Therefore the Jensen is directly compatible.
 
yeah, Sorry about that, I got confused with the Numbering method used for these chips...I thought that since the 5532 is a Dual I figured a 5534 would be a Quad, sort of like with Burr brown chips that are for instance OPA134 is single and OPA2134 is a dual.....


Cheers

:cool:
 
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