UTM INDUSTRY audio transformers - from Poland - EU

[solkatten]

Sorry, I don't understand your question.

Depending on source z the pri inductance is 16H 600ohm or 265H 10K

 

[solkatten]

Happy vacation… those transformer questions can wait till youre back

 

[abbey road d enfer]

Source impedance = 600R or 10k (can't remember), Load impedance = 600R.

i doubt very much the source Z is 10k. Typically generators are either 50, 150/200 or 600, no more.
In order to properly testing a xfmr with a 10k primary, one has to add resistors for reaching a total of 10 000 ohms.
Not all xfmr manufacturers do that. In particular Edcor do not, which allows them to print optimistic data sheets.
Loading the secondary is not necessary for assessing LF response. It is necessary for HF response.

 

[Ricardus]

Happy vacation… those transformer questions can wait till youre back

My question can wait til after vacation, too.

 

[Ricardus]

Hi igs,
thanks for joining this thread, it's great to be able to have more info on the UTM transformers.

I was doing a list with the UTM parts and equivalence to other known transformers so that I know what is available and I can choose that depending on the project.

This is the list I was able to do:

MIC input	Equivalent	Equivalent
UTM2545	Carnhil VTB9045	Neve L10468
UTM2546	Carnhil VTB9046	Neve L31267
Line input
UTM2571	Carnhil VTB9071
Line Level Out
UTM3502	UA-5002	1176, rev A-D circuit
UTM3504	UA-5002	1176, rev A-D circuit
UTM2510	Teletronix LA2A and UA175	UTC A-10 replacement
UTM3523	API2623 output ?	75:300
UTM3503	API 2503 output	300:300

Can you please let me know if this is correct?

Also I though the UTM3502 and UTM3504 were the same transformer with the only difference being the frame and both have in the description "Useful for 1176, rev A-D circuit" , but when checking the specs they have different specs, so what's the difference between the 3502 and the 3504?
The same happens with the 3507 and 3505...

How about equivalencies of these models below, can you provide info on what transformers are similar or what projects are they useful for?

UTM3547
UTM3548
UTM3501
UTM2546
UTM2571
UTM2582

Thank you so much
Best Regards

UTM has 3 Carnhill equivalent multi-tapped inductors as well:


UTM1543 - Carnhill VTB9043
UTM1544 - Carnhill VTB9044
UTM1550 - Carnhill VTB9050

 

[solkatten]

i doubt very much the source Z is 10k. Typically generators are either 50, 150/200 or 600, no more.
In order to properly testing a xfmr with a 10k primary, one has to add resistors for reaching a total of 10 000 ohms.
Not all xfmr manufacturers do that. In particular Edcor do not, which allows them to print optimistic data sheets.
Loading the secondary is not necessary for assessing LF response. It is necessary for HF response.

Im curious but you could also make the case if the sec inductance readings are accurate. The pri inductance is 115H at 100Hz its not impossible that inductance doubles down in the 10 Hz region, Then you got a 10K source Z… Christmas mysteri

I have ordered the UTM3580 15K CT:600ohm P-P trafo. I will measure it when it arrives…

 

[abbey road d enfer]

Im curious but you could also make the case if the sec inductance readings are accurate. The pri inductance is 115H at 100Hz its not impossible that inductance doubles down in the 10 Hz region, Then you got a 10K source Z… Christmas mysteri

Indeed. Inductance measurements should be done with frequency sweeps, not spot. That's where many LCR meters fail.

 

[igs]

igs,

Have you considered making a 2622 API style input transformer using the modern JT-110K-HPC footprint (round with 2 rows of 4 pins)?

We are waiting for the permalloy housings right now. They should arrive at the beginning of 2022.
After that, we'll be able to do these kinds of transformers too.

 

[Ricardus]

We are waiting for the permalloy housings right now. They should arrive at the beginning of 2022.
After that, we'll be able to do these kinds of transformers too.

This is excellent news. I look forward to using them in my next API build.

 

[igs]

Anyway, back on topic it's great to see a new EU source for iron and hats off to UTM and IGS for opening their wares up to the DIY crew. Wonder if there's anything in the catalogue similar to a UTC A-25, that would do for an RCA BA-2C preamp output... (9:1, gapped for 5 or so mA DC).

Yes, we can do this as the EI41, clamped. Please PM me if you are interested.

 

[rock soderstrom]

Yes, we can do this as the EI41, clamped. Please PM me if you are interested.

 

[solkatten]

Hi I recieved the UTM3580 trafo to day…. Started with measure the primary inductance. With a 9K (2x4k7) serial resistance the -1dB was at 11Hz. So -3dB is at 5,5Hz. Primary inductance = ca 260H

 

[gyraf]

Aah thanks! ..And the high frequency corner, still with the 2x4K7..?

/Jakob E.

 

[solkatten]

Aah thanks! ..And the high frequency corner, still with the 2x4K7..?

/Jakob E.

15Kct:150ohm 9K source -3dB at 30KHz but unbalanced to a DI input probably not optimum for high freq response.

15Kct:600 into a lower source z and a balanced load you should get much better hi. freq extension

 

[solkatten]

I will so some more measurment in coming days. But it seems like good universal OPT for tube preamp. With healthy primary inductance of 260H.
PP: 15k:600 or 15k:150 CT
AC-coupled it can do10:1, 5:1 or 2,5:1.

Next I will put it in my PP/SE mic preamp and see how it fairs...

 

[rock soderstrom]

I will so some more measurment in coming days. But it seems like good universal OPT for tube preamp. With healthy primary inductance of 260H.
PP: 15k:600 or 15k:150 CT
AC-coupled it can do10:1, 5:1 or 2,5:1.

Good news, thanks!

 

[jensenmann]

This looks very promising. I´ve ordered a pair right away.

 

[solkatten]

Measured with 20K source and the -1dB is at 18Hz, so -3dB is at 9Hz the first measurment was to close to the soundcards roll off..
The force is strong in this one: pri inductance upgraded to ca 350H

 

[solkatten]

Measured with a 2K source 15kct:600 to balanced load 2K. Flatness 20Hz-20Khz +0dB -0,4dB… I f you look at the very top end you haft to factor in that my focusrite is down 1dB at 35K…

 

[igs]

The same measurement with AudioPrecision. 2k source, 2k load.