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Old 14th February 2012, 02:56 PM   #1
teleman is offline teleman  Norway
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Default BEHRINGER UB1204FX PRO

Hi,
Has anyone done any mods or swapped IC's (JRC4580) on a Behringer UB1204FX Pro mixer? If so, are these SOP or SOIC devices?

Cheers
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Old 14th February 2012, 03:13 PM   #2
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Hi,

I haven't modded this exact type of Behringer product but in all other devices I did mod (A500, DEQ2496, DCX2496, T1953, SRC2496) had SOIC devices on board. I swapped them for OPA2134 on the inputs & OPA2227 on the outputs and added extra supply bypassing. Works like a charme. Beware Behringer does not only solder the parts to the PCB but also uses a small amount of glue! I found that a desoldering hot air gun @ 400C works best for removing these opamps.
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Last edited by Mark.Clappers; 14th February 2012 at 03:19 PM.
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Old 14th February 2012, 04:17 PM   #3
teleman is offline teleman  Norway
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Thanks a million Mark.C,

As you've indicated,the "chips" on these too could be SOIC types!

I was just wondering, you have mentioned that you swapped these JRC xxxx with OPA 2134 & 2227 devices. But, are not JRC 4580 BJT type,while OPAxxxx are JFET tyes? I am thinking on the lines of replacing these with NE5532 or LM4562 op amps. What's your take on this?

If the chips are glued as you've rightly warned me, then it would be a pity,that melting the glue would very likely fry the IC's, thus rendering these unusable. 'Cause JRC 4580 is not all that bad & are widly used in guitar effects & stomp boxes as well.





Thanks again & cheers.

Last edited by teleman; 14th February 2012 at 04:22 PM.
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Old 14th February 2012, 06:04 PM   #4
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From the top of my head the OPA2134 are JFET devices and the OPA2227 BJT

I must admid that a part of the reason I used these devices is that I had them in stock. To me it made more sense to use the JFET devices as input & BJT as output. I also tried OPA2228 but these are not stable in this application and caused oscilations.

After this mod my noise floor was lowered quite a bit, but this is probably a combination of a cleaner power supply & lower noise opamps.

As long as you use an opamp which is stable at unity gain and can handle the supply voltages you should be fine, NE5532 should do a great yob here. The JRC4580 is certainly not a bad opamp for it's price but you can do much better.

When you are already busy inside the mixer check if there are any clocks generated by a crystal and a logic port (inverter). Filtering the supply of this IC with an LC filter and adding a beefy capacitor can do wonders here...

Regarding the glue, i didn't fry the opamps but the PCB itself is far more sensitive. If you pull on the IC a bit with tweezers you can be sure you will have some traces lift off the PCB. be carefull with this, very carefull!
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Last edited by Mark.Clappers; 14th February 2012 at 06:07 PM.
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Old 14th February 2012, 07:30 PM   #5
teleman is offline teleman  Norway
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Thank you again for all your invaluable info...this is exactly what I was looking for! Much appreciated.

You, with a better insight than me in the finer points of modding, I hope, will be able give me some more tips & advice on generally improving this mixer as I dwell into this soon. I've actually uploaded the schematic elsewhere on this thread, so please do feel free to make any comments or improvements as you may deem fit from time to time.

I think,this piece of gear has a lot of potential,by the sheer number of mods done on this by many!
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Old 15th February 2012, 07:31 AM   #6
teleman is offline teleman  Norway
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Sorry,I'm unable to upload the PDF file as it is 605kB & all 10 pages are sequenced (tied) together!
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Old 15th February 2012, 08:59 AM   #7
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I recently moded Behringer UB1002 which is the same series as UB1204. I moded the micpres and the circuit must be the same as they both are advertized being Behringer's IMP "invisible" micpres. I can share micpre schematic and more info if you are interested.

Last edited by CFMartinD18V; 15th February 2012 at 09:29 AM.
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Old 15th February 2012, 04:12 PM   #8
teleman is offline teleman  Norway
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Thank you indeed for your offer with regard to the schematic. I do have the schematic for the UB1204FX Pro.I did try to upload this here,but couldn't as the PDF file size was way over (605kb) the limit allowed on this forum since all the 10 pages are combined or linked, so I don'r know how to export it 1 page at a time!

Please do upload it, as I am sure it'll benefit many. Btw, are the JRC 4580 on these SOIC types? Just trying to be 100% sure. What did you swap these with?

What other (critical) mods have you done to improve the UB1002?
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Old 15th February 2012, 05:03 PM   #9
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This is all very interesting, as I am really interested in upgrading the opamps in some equipment.

One is an old Soundcraftsmen preamp I use mostly for source switching and unbalanced effects sends and returns. It's got lots of other mods, like years ago I upgraded all the interior wire to shielded wire and added power supply caps, added a switch to turn off the RIAA preamp section, added shielding around the power supply,
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Old 15th February 2012, 05:57 PM   #10
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Hi teleman,

I can't find the schematics, I did a quick google search but that came up emty to.

If you can share (a part of) the schematics, I'll have a look.

Hi Cyclecamper,

If you have some room to spare inside the device you could have a look at really filtering the supply of the opamp, not just adding extra capacitance. A simple way to try (i use it a lot in my designs, both DIY and professionally) is a 10uH coil in series with the supply and a 10uF ceramic or tantalum cap to ground. cheap, simple, quick mod.
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Last edited by Mark.Clappers; 15th February 2012 at 06:02 PM.
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