UTM INDUSTRY audio transformers - from Poland - EU

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Well, if a lot of people still are going OT including "Mr. No Grievances" than allow me the same. If this is purely a tech support thread than ok maybe it doesn't need to be in the white market. But given that new products are also announced here and people sharing their experiences maybe it does. I do not mind either way, and I especially do not need to read the last couple of pages where people without grievances KEEP ON airing grievances, clearly off topic of this thread so yeah.
I've used the ignore button now, so that'll help.
Sorry to Igor, he makes most excellent transformers, keep up the good work!
 
Disagree. At this point, and given the title, I think ownership of this thread belongs to Igor. Please take this discussion elsewhere.

Ownership of this thread belongs to GroupDIY forum and not Igor or anyone else.
Although I started the thread and still think it was a good idea after seeing so much interest and help around here, it doesn't belong to me also.

And above all anyone is free to write what they want here or talk about the subject they feel relevant to this thread, it doesn't matter if you or anyone disagrees, as long as there's respect and don't break any forum rules, everyone is free to write here.

Personally I feel that at the moment that it's relevant there was an uncalled threat to lock it and that the 3 moderators avoid any explanation, and I will write about it with no problems if I need to.

You or anyone else, that might attack me and continue to undermine what happened, don't seem to know that you are only able to write in this thread and it still exists because of me, I defended this thread from being locked already 2 times, first one in posts 305 and 306 and the second one was last week posts 323 and 325. I also defended it again in the last days from being a commercial thread, posts 353 and 355.
So whoever comes here and undermines the situation, writes here like if nothing happened and shows very disturbed about complaints that were made in this thread, don't know what you are talking about. You only have the privilege of writing here in the first place because someone defended it

Best regards Ricardus and good DIY as I know you are a true and great DIYer
 
Had little adventure with fitting UTM0547 transformer in t.Bone SCT2000, with some creativity and tolls we made it.
UTM transformer in combination with K47 capsule/12ay7 tube minus few capacitors (standard ccda mod) in SCT2000 sounds royal!!

IMG_0420.jpegIMG_0424.jpegIMG_0423.jpeg UTM transformer can be used with Apex 460/Nady 1050 or any other Chinese tube mic with few cuts on bell housing at the bottom of the mic.

@igs set new standard for customer support. Highly recommend folks to buy from.
 
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Yeah, sometimes it takes a little creativity to fit parts into a case. Easy solved UTM0547 Transformers on Poctops U47 Tube PCBs. Fits perfectly in the big China U47 Bodies. I used a cheap M2 Screw set from Amazon with plastic washers inbetween to mount. And drop of nail polish to fix the nut...
 

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nice hack

could the magnetic properties be intermittent/lams shorted?
No damage to transformer has been done, everything works, no issues.
I asked Igor if lams can be trimmed at edges to fit into bell housing. That’s not recommended.

Cheers
 
Just received our first samples of UTM output transformers. Tried the UTM 3504 which is gapped, and am seeing a significant roll off at low frequencies. Is that a side effect of it being gapped? Technically the transformer doesn't need to be gapped in this application, there would never be any DC across it, we mostly liked the sound of a gapped Carnhill we listened to in a similar application and circuit.

Is there a fundamental sound difference between gapped and ungapped transformers, assuming the impedances are similar?

Thanks!
 
Is there a fundamental sound difference between gapped and ungapped transformers, assuming the impedances are similar?
Well, a gapped transformer has always less inductance (lower impedance) than a non-gapped one of otherwise identical characteristics.
That's why gapped xfmrs are usually larger than their non-gapped counterpart, for a similar bass response.
Alternatively, for a similar size core, they would require more turns of thinner wire, which would result in increased losses.
 
Alternatively, for a similar size core, they would require more turns of thinner wire, which would result in increased losses.

It seems that was what was done with LO2567 and the LO1166 used by Neve.
Both are the same size and winding structure, the LO1166 is the gapped version of the LO2567

The 2567 being non-gapped has less turns and thicker wire

Screen Shot 2023-09-01 at 03.53.27.png

The LO1166 being gapped has more turns and thinner wire

Screen Shot 2023-09-01 at 03.53.03.png

This info is from CJ's docs.
Thanks CJ
 
Another question on the gapped UTM 3504. We are driving it with a relatively simple mosfet voltage follower and are seeing first a noticeable output level bump at around 15-20 khz, followed by a dropoff at higher frequencies. The datasheet states a frequency response of 20 hz to 80 khz, which we are clearly not seeing.

Question - could this have to do with how we are driving the transformer? The frequency response at the mosfet driver stage is flat. Do we perhaps need a small resistor in series, or a small inductance like they do for the 990 DOA? Or would a Zobel network help, and how do you pick the right values?

Thanks,

- Bertu
 
The UTM3504 is a gapped transformer dedicated to 1176 rev A/B. The frequency response of the transformer is similar to UTM3502 and shown on the attached diagram.
I heard some feedback from 1176A builders and they are happy with their results using 3502/3502. Sure, you can use a Zobel filter on the output.
1694847094475.png
 
Had little adventure with fitting UTM0547 transformer in t.Bone SCT2000, with some creativity and tolls we made it.
UTM transformer in combination with K47 capsule/12ay7 tube minus few capacitors (standard ccda mod) in SCT2000 sounds royal!!

View attachment 112014View attachment 112015View attachment 112016 UTM transformer can be used with Apex 460/Nady 1050 or any other Chinese tube mic with few cuts on bell housing at the bottom of the mic.

@igs set new standard for customer support. Highly recommend folks to buy from.
why do you remove c7 and c6? what do it with the sound?
 
I recently finished up my own little 500-series version of Ian Thompson Bell's REDD eq using the UTM 2571 input transformer and the 1543 and 1544 inductors in the eq circuit. Here's a thread with a little more info about the project. Thanks to Igor for making these options available to us!
Oooh. Looking good. Would love to build some of those.
 
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