Behringer UB1204-PRO Mods

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12Bass

Active member
Joined
Jul 27, 2007
Messages
42
Hi Everyone,

For some time I've been interested in modifying and improving the sound quality in various pieces of sound equipment. A few years ago I bought a an inexpensive Behringer UB1204-PRO for recording small projects. At the time of purchase I compared the UB's "IMP" preamps to an older Mackie (non-VLZ), Audio Buddy, and an older Behringer MX1204 mixer. To my ears, the UB preamps were clearer and better sounding than the others. Later, after owning the Behringer for a while I compared the UB preamps to a Mackie VLZ Pro and thought that the VLZ Pro preamps were a bit more natural and open sounding. So, given that I'm presently working on another recording project, I thought I'd see what I could do to improve the sound of the UB1204's preamps to make them satisfactory for tracking.....

After recently finding the high performance LM4562 and AD8599 op amps, I thought I'd try replacing the stock JRC4580 with an AD8599, since I already had one in the SOIC package. Compared to the regular JRC4580 channels, both a friend and myself are readily able to discern the improvement in sound from using the AD8599. Most evident is the increase in "air" or openness of the sound. Also, the AD8599 sounds cleaner and more even across the frequency spectrum. The lows sound better, more natural, too. Noise also seems to be reduced slightly.

I'm planning on ordering another AD8599 (SOIC only) and a couple of LM4562s in SOIC for the remaining three channels. That will give me two channels of AD8599 and two LM4562. Are there any other modifications that might be worthwhile for this unit? Given that it uses SMT, it can be a bit trick to modify. Does anyone happen to know where I might find a schematic for this mixer? That would be helpful!

On a side note, shortly after purchasing the UB1204 I opened it up to install inserts right after the preamp section and before the mixer's channel strips. There is a connector between the input PCB and main PCB which can be used for this purpose. I recommend this modification for anyone looking for a better quality direct output from their mixer. The sound from the insert is noticeably clearer than the main output.

I highly recommend replacing the stock JRC4580 op amps to improve the sound of the Behringer preamps.
 
A couple of days ago I replaced the remaining NJM4580s in the preamp sections of channels 2-4 of the UB1204 with another AD8599 and two LM4562s. Now channels 1-2 have the AD8599, while 3-4 have the LM4562. Although the sound of op amps seems somewhat circuit dependent, again I have found that the LM4562 is a bit more open and transparent than the AD8599. In comparison, the AD8599 seems to have a bit more of a warm, euphonic, round sound, while the LM4562 sounds more transparent and sonically neutral.

IMO, the new op amps really bump up the quality of the Behringer preamps. Both upgraded op amps are a significant improvement over the 4580. What they seem to do is help bring out that little extra air and subtle detail which gets lost in lower fidelity preamps.

I'll probably use the LM4562 channels when I'm looking for uncolored transfer of the input signal and use the AD8599s when a bit more warmth and roundness is called for.
 
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