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Installing Behringer OT1 transformers
Old 1 week ago
Installing Behringer OT1 transformers

I've recently picked up some old Behringer rack gear (PEQ305 and an MDX compressor) and recently also tracked down some OT1 output transformers.
I'm interested in doing the upgrade, I just have one question that I can't find a definitive answer for.
Other than soldering in the transformer itself, do I just first remove the two resistors sitting in the middle of the transformer slot, or is there anything else I need to do in order to install them properly?
Old 1 week ago
Gear Addict
weave's Avatar
1 Review written
๐ŸŽง 5 years
I am very interested in this upgrade you are contemplating and although I have no answer for you I would like to ask that if you do mod that maybe you take a few before and after pics and post them and maybe a thought or two on issues etc. I would be very grateful and will be watching this thread to see where it goes.

Old 4 days ago
So I unfortunately got pretty into it with the Peq305 right when it arrived - I opened it up to make sure it had the slots and the OT1's arrived with it still open so I neglected to get a before pic. I grabbed a pic from an old reverb listing to show what it looked like before though, you can see the slots for the transformer around the two little yellow resistors with the single line. The only difference with mine was a sticker was over some of the holes but it came off easy. On a side note, the board is pretty different from the mdx - everything is neatly arranged and thru-hole, lots of room and looks like it would be easy to repair.
The underside of the board had solder where the transformer would go (similar to pic attached but that might be an after pic since the resistors are out) - it melted extremely easy and only took a single pass with the solder vacuum. Likewise the resistors were extremely easy to desolder, one just fell out.
The transformer dropped in with a little coaxing, and was pretty simple to solder.
I really should have used the unit more beforehand because it's pretty hard to gauge the sound difference when I only tested it on speech, but in any case I used the upgraded version in a stream the same night and it performed admirably and seemed a bit fuller and less noisy than before but again I didn't do enough testing so it could be placebo. I am surprised how much gain this thing has and without that behringer muddiness that you sometimes get.
I hope this helps a bit! Apologies for not doing a proper audio test but maybe when I do the mdx I can - I do think someone in the forums did already do a before/after with the mdx though, worth a listen because the difference I heard in the peq305 was similar to his clips.
My BEST advice: contact music tribe's parts department about the transformers. They're like 6 bucks plus shipping, I maybe paid about 12 per transformer total. Less money and work than buying the old DI's and ripping them out, at least where I live where they run 30 plus shipping.
Attached Thumbnails
Installing Behringer OT1 transformers-img_20210510_171042.jpg   Installing Behringer OT1 transformers-img_20210510_172858.jpg   Installing Behringer OT1 transformers-img_20210510_171219.jpg   Installing Behringer OT1 transformers-vetdjzkyqujgtieic9hs.jpg   Installing Behringer OT1 transformers-img_20210510_172957.jpg  

Old 4 days ago
Gear Addict
weave's Avatar
1 Review written
๐ŸŽง 5 years
Thank you for the follow up and the pics!
Old 3 days ago | Show parent
No problem!
Did the autocom today, and here's some pics during the process. I did the same thing and it worked, main weird difference is that the slots are on the other side of the xlr outputs so you're soldering them on the opposite side. The resistors were a fair bit fussier to remove because of the smaller holes and the smaller amounts of solder being harder to melt but the slots for the transformers didn't have solder in them which saved a bit of time. Putting it in was easy though the angles are a bit tougher with the xlr there.
In general it's a pretty doable upgrade if I was able to do it without issue. The sound differences have been covered on the forum but what stood out to me on a quick vocal test was that it seemed to clip differently when cranked (more saturated - could be my imagination) and had a bit more presence in the low end.
Attached Thumbnails
Installing Behringer OT1 transformers-img_20210511_124259.jpg   Installing Behringer OT1 transformers-img_20210511_124237.jpg   Installing Behringer OT1 transformers-img_20210511_124241.jpg  
Old 3 days ago
Here are the ot1's installed. One weird thing I noticed is that there's two slots for capacitors on the board that are empty.
Attached Thumbnails
Installing Behringer OT1 transformers-img_20210511_131549.jpg   Installing Behringer OT1 transformers-img_20210511_131544.jpg   Installing Behringer OT1 transformers-img_20210511_131539.jpg  
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