A little help evaluating price/value of two Sowter transformers

[Windcrest77]

I'm in the process now of fabricating a project that uses transformer coupling at the input, 600 to 10K line transformer. I would like to get Sowters but for the two models I'm looking at the price nearly doubles one vs the other. The project I'm doing is on another post here, basically a computer desk amp where I might have 6-8 different sources plugged in at once sharing the ground. So I want a transformer input to alleviate ground loops and get some gain.

Can someone more familiar with input transformers tell me what I am getting for the extra money between these two models? I understand that quality vs price is never linear, but I have no problem spending for the more expensive model if the sonic reward is measurably greater.

USD $74

https://www.sowter.co.uk/pdf/8540.pdf

vs...

USD $138

SOWTER TYPE 3575 TRANSFORMER

Here are some of the advantages I've garnered so far for spending more on the 9063 model:

1) I can have a balanced input source as well as all my RCA sources.
2) More headroom and inductance, all the sources will be from op-amps (CD, DAC, Random headphone output of a phone, Bluetooth adapter, my DJ fader, etc). Some sources may be "hotter" than others.
3) More bandwidth
4) Better distortion
5) Having separate secondaries offers more parallel/series design choices for wiring it up.

What do you think? Should I spring for the $138 model? We only live once.

 

[audiowize]

I'm in the process now of fabricating a
Here are some of the advantages I've garnered so far for spending more on the 9063 model:
1) I can have a balanced input source as well as all my RCA sources.

The 8540 doesn't allow this? Why not?

2) More headroom and inductance, all the sources will be from op-amps (CD, DAC, Random headphone output of a phone, Bluetooth adapter, my DJ fader, etc). Some sources may be "hotter" than others.

The 9063 has a higher maximum operating level. The 8540 will take about 5V RMS, the 9063 will take 12. I really doubt you have much more than 2 available from most of your sources.

3) More bandwidth

Maybe.

4) Better distortion

This is another maybe. One has a rating at 1kHz, the other at 50Hz. It's likely that the larger of the two would have lower THD, but if you're operating them both at 2V of signal, the difference may not be all that large.

5) Having separate secondaries offers more parallel/series design choices for wiring it up.

Extra gain is very rarely needed!

What do you think? Should I spring for the $138 model? We only live once.

I think you're building a desktop amp. I would use the Sowter 4600 or a pair of Altec 15335.

 

[Windcrest77]

The 8540 will take about 5V RMS, the 9063 will take 12. I really doubt you have much more than 2 available from most of your sources....

Extra gain is very rarely needed! ....

I think you're building a desktop amp. I would use the Sowter 4600 or a pair of Altec 15335.

Thanks! You're right, at 2V, paying for pro voltage bandwidth and distortion specs is probably overkill. The 8540 doesn't have a center tapped primary to take a 600 ohm balanced XLR source. My DJ fader has both RCA and XLR outs, probably not necessary for me to include an XLR input source. This model seems to be similar 8540 but with a CT primary:

SOWTER TYPE 4383 TRANSFORMER


Thanks, this helps a lot!

I'll probably order two 4600 1:1 transformers and two 8540 1:4. I'm using an ElectraPrint design that specified a 600:10K line transformer, but I can experiment that design using both 1:1 and 1:4 on the breadboard. Eventually I'll use the parts in another project. With the Altec I'd have to be watching ebay for the next few months, so Sowter it is.

 

[audiowize]

You don't need a center tap on the transformer for balanced input...

 

[Windcrest77]

Wow sticker shock made me abandon my shopping cart at the Sowter site. What the heck is a VAT tax? ouch. Much too costly for two pairs of transformers, I'm sure they are stellar performers, but that VAT tax and shipping is something I wasn't ready for today. I can get Jensen isolators locally with free shipping and no tax. So I'm compromising on the step-up level. My original schematic had 1:4, I could go with 1:1 but Jensen has a bit of a compromise here with a 1:1.4. So I'm going to take the middle road:

https://www.parts-express.com/pedoc...mer-for-vacuum-tube-line-input-data-sheet.pdf

Thanks again, I think the 10K input impedance will be more versatile than the 600R, and I'll still get a little gain.

 

[audiowize]

You don't have to pay VAT if you're in the US.

 

[Windcrest77]

You don't need a center tap on the transformer for balanced input...

I see now how to hook that up:

https://www.parts-express.com/pedoc...mer-for-vacuum-tube-line-input-data-sheet.pdf