output transformer - type of steel and affect on tone

[pula58]

What do you folks think about the type of steel used in output transformers? Seems like when I get OT's with grain-aligned M6 steel that they seem brighter, in a way that I don't care for.

Any opinions on this?

[Stevem]

If they are interleaved wound that's one reason for sure why it might be brighter, I do not know about the core metal?

[Firestorm]

That is a great question that I have no knowledge about. Moose had some insight when he was trying to spec Express OTs. Any EM guys have a thought?

[Leo_Gnardo]

Might be intended for hi fi use.

I've run across Mercury OT's intended for medium size Fenders (Fender A6A for Bandmaster and similar) sounding razor-sharp bright, not at all what we expect for Fender tone. Did MM think they were making an "improvement"? Reminds me of:

[Firestorm]

Leo, as you know, some Fenders sound good, some sound like voice of God. But I don't think it's the transformers, more likely the way the PI is structured. Like HAD did.

[Cantplay]

You could also add to this discussion the effect of lamination thickness.

John

[Firestorm]

Yeah, I'd like to know why.

[rp]

M6 makes a difference I can clearly hear, doesn't mean bad doesn't maen good. In my limited experience in vintage clones with a few Hammond 1600 series and one Audio Note 2XEL84 type I didn't like the sound, tone was skewed towards buzzy, zippy if not exactly bright, not warm, loose, open, sounded kind of '80s not '50s - '60s if you know what I mean, kind of like shotgunning with 715 caps. But that doesn't mean much, the Edcor in my 5C1 sounds much clearer and brighter and totally non-original tone but it's a bad-ass sound. The Hiwatts, Oranges, Sound City used hifi Partridges, I'm guessing were M6. Many here love the A470 in various builds, all the Edcors used and liked here are M6. However one man's Little Debbie Swiss Roll is an other's Sacher Torte, hard to tell on the internet.

So it's a case by case thing. If you're going for an accurate vintage clone or a restore that din't use M6 I'd say stay away from M6, I'd stay away from bobbins too, which is why I prefer paper wound Heyboers, haven't tried MC. I don't think most vintage circuits were voiced for too much bandwidth so when you upgrade parts the tone skews. Otherwise, if you experiment you might stumble across a cool mix like my 5C1 w/ the Edcor, but you might also wind up with a couple of hundred bucks in OTs that have to go on eBay.

I heard vintage Marshall OTs were M6 - anyone know if true?

[Leo_Gnardo]

Leo, as you know, some Fenders sound good, some sound like voice of God. But I don't think it's the transformers, more likely the way the PI is structured. Like HAD did.

In the Bandmaster I mentioned, bone stock everything except for MM OT. RZZZZZZ !! Yikes! Tubes and circuitry all worked fine. Swapped in a stock used A6A and got the right tone back.

[pula58]

I have had Fender blackface-like buids where I tried Heyboer (custom, with M6) - too brite, Magnetic comonents-too brite, Hammond (from their Fender drop-in line of OT's) - just right.

I have no idea why!
It is getting expensive to blindly try OT'ds. Plus, A-B-ing is kind of a pain.

I wish I knew how to specify the OT's to a custom transformer builder to get it right (to my ears).

[roberto]

This is what I collected few years ago about trafos:
http://www.slocloneforums.com/viewtopic.php?f=24&t=5517

[Stevem]

gnardo I have that Mothers of invention record to I this day and listen to it once or twice a year!

I have a Ferrets as pets also but I have never used one to shave with! Lol!

In regards to the OT thing, for guitar do we really need one that can go passed 10k with out rolling off, not in my book?

I've got a 1967 a Kustom brand SS amp with a phase inverter transformer and people say they sound like crap due to that. Well the last one of these I fixed I tested the frequency response of that PI transformer and it was flat all the way to 15k, so it was just the way the preamp was designed that it was a mellow sounding amp!

[Alan0354]

I am no expert in OT and I am not going to comment on the steel used. I can only tell one of the experiment I did that I switch the OT between a Classic Tone Vibrolux OT and Classic Tone Marshall Plexi 50W OT. The dimension ratio and size are totally different. I fully expected to hear a clear difference. I set it up with protection that I can switch OT instantly by a switch hot so I can actually go back and fore listening instead of go by memory. This is the best test I can think of as everything else remain the same, the guitar, the amp.....all the same, in the same room.

I cannot hear a dent of a difference!!!! I was absolutely stunned. Maybe my ears are not that good, one of you that have golden ears might be able to tell. I switched back and fore and back and fore, I couldn't tell a difference.

Seems like I can make much more difference by changing a value of a coupling cap, a tone cap etc. When I change the tube from 6V6 to EL34, I can tell a difference right away just by memory.

[Alan0354]

Leo, as you know, some Fenders sound good, some sound like voice of God. But I don't think it's the transformers, more likely the way the PI is structured. Like HAD did.

In the Bandmaster I mentioned, bone stock everything except for MM OT. RZZZZZZ !! Yikes! Tubes and circuitry all worked fine. Swapped in a stock used A6A and got the right tone back.

Ha ha, maybe it's like good food, you don't necessary need expensive components, you can cook fantastic tasting food with ordinary components with a lot of love and touch!!!

[Leo_Gnardo]

I have a Ferrets as pets also but I have never used one to shave with! Lol!

NYC - thank goodness former - Mayor Giuliani, the one who couldn't keep his pants zipped, banned New Yorkers (city) from having ferrets as pets. "Who would want to have a weasel as a pet?" If he wants to see a weasel, all he has to do is look in the mirror. RZZZZZZZZ!

Back to subject of thread...

Seems most guitar amps, no problem if the OT rolls off by 10K or so. IF someone wants to build a more Hi Fi amp, say for acoustic guitar or guitar synth, now we have some idea who's got what.