UTM INDUSTRY audio transformers - from Poland - EU

[Heikki]

Anybody plan to put some of these PCBs in production ? I'd be interested in a pair.
Thanks !

Not to step on toolshedamps toes but I have some extra ones I can sell.

 

[toolshedamps]

No worries, I told Igor that since I had many pcb's made that I'd offer them to the community for the cost of postage. Thanks! Matt.

 

[TimG]

Ordered August 14th -arrived safe and sound August 28th to East Coast USA.

Thanks Igor!

 

[f.aiseur]

Hi everyone,

For a LA2A project, I plan to use both UTM (2510-In and 3515-Out), so my question is : could you suggest a better solution to mount them?
As you can see on the pictures, i "secured" the Input Tx with two aluminium plates, but there is still some gap between the transfo, the plates, the case...
For Output Tx, do you think it'd be better to mount it opposite, inside the case, so the cables stay inside?
Would i need to fill the gaps?
I guess the best way would be to make specific adapter plates, but i'm not equiped for that, so if anyone use those Transfos for LA2A, how did you mount them?

Thanks, as always, for your inputs, great help, and have a lovely day

 

[TwentyTrees]

Yes, the output transformer isn't shielded so should really be mounted inside the case

 

[abbey road d enfer]

For Output Tx, do you think it'd be better to mount it opposite, inside the case, so the cables stay inside?

You should experiment. The only notable difference would be regarding the magnetic filed from the power transformer? Since you have an aluminium chassis, it does not provide magnetic shielding, but the flux lines are probably different. You should experiment with the orientation also. Regarding electrostatic shielding, the impedances are low enough to make it negligible.

Would i need to fill the gaps?

No.

I guess the best way would be to make specific adapter plates, but i'm not equiped for that,

If you made this chassis, there is no reason why you couldn't make adapter plates.

 

[f.aiseur]

You should experiment. The only notable difference would be regarding the magnetic filed from the power transformer? Since you have an aluminium chassis, it does not provide magnetic shielding, but the flux lines are probably different. You should experiment with the orientation also. Regarding electrostatic shielding, the impedances are low enough to make it negligible.

No.

If you made this chassis, there is no reason why you couldn't make adapter plates.

Thanks!! I will experiment
Isnt it going to be an issue then that this chassis is made of aluminium?..
I bought it as is, just made a few holes in it..
So i’ll probably use a metal bracket from hardware store because i can’t cut metal, i only can drill holes

 

[abbey road d enfer]

Thanks!! I will experiment
Isnt it going to be an issue then that this chassis is made of aluminium?..

It may or may not...
An aluminium chassis does not shield from external fields, but OTOH steel can channel flux lines and orient them in a eird manner, which can result in increased noise.

So i’ll probably use a metal bracket from hardware store because i can’t cut metal, i only can drill holes

I bet one day you'll have to have a hacksaw and a vice.
Meantime can you ask a friend?

 

[thomasdf]

Thanks!! I will experiment
Isnt it going to be an issue then that this chassis is made of aluminium?..
I bought it as is, just made a few holes in it..
So i’ll probably use a metal bracket from hardware store because i can’t cut metal, i only can drill holes

I am in the process of building a LA2A with UTM transformers too, and I have an analogue vibe chassis... which means I'll make some adapter plates one of these days (I'll CNC them). Send me a PM and I'll see if I can make a few more. I just don't know when that will be because I have quite a lot of projects on going. But by the end of the year, for sure.

 

[toolshedamps]

Hi everyone,

For a LA2A project, I plan to use both UTM (2510-In and 3515-Out), so my question is : could you suggest a better solution to mount them?
As you can see on the pictures, i "secured" the Input Tx with two aluminium plates, but there is still some gap between the transfo, the plates, the case...
For Output Tx, do you think it'd be better to mount it opposite, inside the case, so the cables stay inside?
Would i need to fill the gaps?
I guess the best way would be to make specific adapter plates, but i'm not equiped for that, so if anyone use those Transfos for LA2A, how did you mount them?

Thanks, as always, for your inputs, great help, and have a lovely day



View attachment 98026View attachment 98027

If you want to mount the unshielded output transformer on the outside of the chassis (although as stated the aluminum chassis isn't going to provide shielding anyway) I'd buy some steel transformer covers like these...... (see link below) to shield it.

https://www.goodcomponent.com/produ...-case-enclosure-90x80x90mm-gdtc0015-1056.html
They work really well.

 

[toolshedamps]

Does anyone know if the UTM7070 has ultralinear taps on the primary winding? There doesn't seem to be a "contact" tab on the website and no further info on these transformers is in the latest catalog (2c) pdf.

Thanks! Matt.

 

[Ricardus]

I see you make a Low Profile version of the 3523 for 500 series module. Do you make the same for the 3503?

 

[igs]

Does anyone know if the UTM7070 has ultralinear taps on the primary winding? There doesn't seem to be a "contact" tab on the website and no further info on these transformers is in the latest catalog (2c) pdf.

Thanks! Matt.

No, this transformer is dedicated to Sansui AU70 power amp. This is a special kind of cathode negative feedback. The schematic is attached.

But we can do a similar transformer with the UL taps for any kind of output tube. Just PM me what you need.

 

[igs]

I see you make a Low Profile version of the 3523 for 500 series module. Do you make the same for the 3503?

Yes, no problem.

 

[Ricardus]

Yes, no problem.

Ah, excellent. I will be getting the 3523's first and the 2622's.

 

[abbey road d enfer]

No, this transformer is dedicated to Sansui AU70 power amp. This is a special kind of cathode negative feedback.

EDIT

It's just a standard Williamson amp with the usual arrangement of NFB taken from the 16 ohm secondary.
Actually, the secondary is a 16ohm+16ohm, and indeed each goes to the cathode of the output tubes, so yes, it's cathode NFB.
One again, I forgot to turn the brains on before typing.

However, it is peculiar because of the weird arrangement for the headphones output.

 

[toolshedamps]

It's just a standard Williamson amp with the usual arrangement of NFB taken from the 16 ohm secondary.
However, it is peculiar because of the weird arrangement for the headphones output.

That........ and, it looks like the output tubes are biased strangely as well. Thanks!

 

[abbey road d enfer]

it looks like the output tubes are biased strangely as well. Thanks!

Fixed bias, at -18V. Nothing curious about it.
It's somewhat uncommon, because the EL84/6BQ5/7189 has been designed to have almost equal performance in cathode bias than in fixed bias, but considering the choice of cathode NFB, it definitely makes sense.

 

[toolshedamps]

EDIT

It's just a standard Williamson amp with the usual arrangement of NFB taken from the 16 ohm secondary.
Actually, the secondary is a 16ohm+16ohm, and indeed each goes to the cathode of teh output tubes, so yes, it's cathode NFB.
One again, I forgot to turn the barins on before typing.

However, it is peculiar because of the weird arrangement for the headphones output.

Ahh, in any case, not my cup O' tea. I've designed a SE (5842) -> IT -> Pair EBL21 (UL connected), CCS bias PP amp and will be "auditioning" 8K-10K primary OT's over the winter to see what I like... the UTM7070 was one of them that I was hoping to try. I'll just PM him directly. Thanks!

 

[zamproject]

Hello

@igs . Interested to know if you can wind coil former for standardized RM or E series from TDK/EPCOS ?

Best
Zam