[MathGuy]

So have any of you yet tried these Solid-State Output Transformers yet from Promitheus Audio?

I'm talking about these ones: Click Here

I've received a couple of these (600 Watt finished-product versions!) from Promitheus Audio this week - haven't had a chance to try them yet, but pretty excited to see what they can do!

Anyone else, or am I the first one?  aa

Is there interest in a review and/or pics?  aa

[*Scotty*]

MathGuy, please post your system so we can know what amp and speakers you are going to be using these guys with. This helps give a context
to your remarks about the transformers, pro or con. Please report on your experiences with these pieces of equipment.
Scotty

[fvale]

Hello everybody. A couple of months ago I bought two 100W SS output transformers (bare) from Promitheus and I've to say I'm still shocked about the sound! It's a MAJOR improvement, hard to believe as (after a few hours of burn-in) you would not recognize the system as yours! But don't misunderstand me, I wasn't able to find ANYthing negative on sound.
My power amp is a slightly modified old Audionics CC3 amp (80W/ch.) which drives a couple of vintage Altec 605A duplex in a big cabinet.
Bass seems to be be more deep and more musical and mid range is more realistic. I didn't notice any high frequency attenuation, even at top end. Look at the description of these transformers on Promitheus web site, I found it to be realistic.
Furthermore I'm happy to be able to protect my 40 years old valuable Duplexes from DC!

Ciao from Italy.

[vkaiwar]

I purchased a pair of 250-watt output transformers from Nicholas Chua in July, to go with my Promitheus Audio TVC and a Hypex ucd180 amp made by Tim Rawson.  The main improvements are in three areas:

1.  A better sense of timing and rhythm.
2.  A greater sense of space and lateral imaging.  My speakers are too close to the wall to assess image depth.
3.  Better tone on a range of instruments; bass is especially good.  Massed voices and instruments are nicely textured instead of sounding amorphous.

Overall, if I were to give a non-expert summary, my speakers [Mission 752F] sound more like good single-driver speakers.  There is overall a greater feeling of presence and immediacy.  Perhaps this is due to the amplifier not having to drive the speaker's crossover.  I want to try my amp/transformer combo with a single-driver speaker.  I have a pair, not the greatest, but it might be worth trying as an experiment.  A lot of people who might be tempted to spend money on upgrading their amplifiers might try these output transformers first. 

[MathGuy]

Hi AudioCircle folks,

Didn't want you to think I forgot to follow up here!

The transformers arrived very banged-up from DHL, and were closely inspected by US Customs and Border Patrol on their way through shipping as well (Nicholas thought they might have been worried, that the transformer boxes contained a bomb or drugs or something of concern). Thankfully after a little effort, I was able to clean them up and get them solidly put back together.

I am having one main problem with these transformers so far, that I'm sure Nicholas will help me resolve. With the transformers in place, there is a very significantly loud pop that now comes from my speakers, when I turn off my Musical Fidelity amplifier. It is loud enough that I am worried it might damage my speakers (Joseph Audio RM7si Signature MK2's).

I'm still doing some careful listening to determine what effect these transformers have in my system, and will report back if anybody remains interested.

Cheers!

[MathGuy]

Just an update:

I have tried to do some more careful listening with the output transformers in place - but this has been extremely limited due to my above stated concern, about the very loud pop that now comes through my speakers when shutting off my amp. I don't want the result of using these transformers, to be permanent damage to my speakers!

So hard to say anything further until this problem is better understood and controlled.

I have known Nicholas for some time now, and he has always come through for me before. He has told me to wait for his futher input on this problem, while he tries to determine what is happening here. I have confidence that he will get back to me eventually with his input, and hopefully with a solution to the problem.

Anyone here know how to approach fixing this issue? It would be good to get some ideas, while I'm waiting for Nicholas to get back to me. I will also post here again when I do hear from Nicholas.

[Steve Eddy]

Just noticed this thread and while I'm a big fan of transformers myself, I wanted to address something which was said in the link in the original post:

When your amp drives a purely inductive component like a transformer, it does not see your speaker wild reactive loadings but instead it sees a very stable high impedance  load from by the inductance of the transformer which does not fluctuate under load or frequency .

This is incorrect.

Transformers don't have any particular inherent impedance of their own and do not turn a varying reactive load into a stable load. What transformers do is reflect impedances. In other words, the load connected to the transformer's secondary is reflected to the transformer's primary and the source impedance driving the transformer's primary gets reflected to the transformer's secondary.

Impedances are reflected as the square of the transformer's turns ratio. If the turns ratio is 1:1, then the load impedance gets reflected to the primary by a factor of 1 and the amplifier sees the same impedance that it would otherwise. If you use a step-down transformer, say a 4:1, then the load gets reflected to the primary by a factor of 16. So the amplifier will see a nominal 8 ohm loudspeaker as a 128 ohm loudspeaker.

However it doesn't see a stable 128 ohm load. The varying, frequency dependent impedances of the loudspeaker all get multiplied so the amplifier still sees a load that varies with frequency.

And of course if you're using a 4:1 step-down, the amplifier's output voltage get stepped down by a factor of four (the turns ratio) so you need to make sure your amplifier has enough excess voltage gain to overcome the step-down transformer's loss of voltage gain.

Anyway, this isn't any sort of comment on the product itself. Just clarifying how transformers actually function.

se

[Early B.]

For those who are using these transformers, can you post pictures? I want to see how you have them hooked up.

Thanks.

[kp93300]

Hi All,
Are this transformer similar in function to the Richard Gray power supply products?

KP

[DanTheMan]

MathGuy, do you know the ratio of turns in the OPTs?

Also, does anyone know why their installation could cause a turn on thump?  Seems strange that they would do this as the should have a very high resistance to DC.

Thanks,

Dan

[MathGuy]

MathGuy, do you know the ratio of turns in the OPTs?

Also, does anyone know why their installation could cause a turn on thump?  Seems strange that they would do this as the should have a very high resistance to DC.

Thanks,

Dan

Nicholas advised me that the solidstate amp would see an impedance of 75 ohm (a much easier loading) but for power purposes it would still give out as according to 8 ohm or 4 ohm loading.

He also mentioned that the loud popping sound from my speakers, when turning off the amplifier, must be due to my amplifier somehow not working well with the transformer loading.

Also as I mentioned earlier, I've enjoyed Nicholas' products since I first ordered a version 1 TVC quite some time ago, and with several other orders from him since then. He has always made sure everything was good, and I trust him - he takes very good care of his customers, and I know that he will make sure everything is right.

I will be posting again here soon, about his solid-state DAC (silver pulse transformer upgrade, balanced outputs).