Best Output Transformer

[mlp-mx6]

Reply to the hijack -

Moose, I want to say I appreciate you for making these trannies available to the rest of us. I have ordered from you before (before you changed the steel) and will order again (soon, I hope, for a Rocket set).

[geetarpicker]

I remember Glenn talking about being at Kens, and playing another wreck with different transformers than the one in his amp. And he liked that amp also. I think, if i remember, the amp he played had a black OT or more like the Stancor. And Ken saying something like one had a more bluesy sound.. Glenn might be able to explain it better.

The first Express I ever played was a grey (I always assumed Stancor according to Ken) transformer model from the mid 80s. It was and probably still is owned by a guitar/electronics shop in Maryland. The owner of the amp was friends with Kenny from way back. The amp's top was also used in the shop as a cutting board for sub sandwiches! The owner let me borrow that amp for a week and I gigged with it at the well known and now gone "Bayou" club in Washington, DC. I was sold and then "got on the list". My gut feeling when I later got my Pacific transformer Express was that it was slightly more mid focused, slightly more aggressive, and maybe had slightly less deep lows. I don't remember much difference in the brightness but it was months between hearing the two amps.

In the early 90s I also played some other amps up at Ken's and at the time Ken was really trying to talk me into a Rocket. I played his original red Fuzz Face through his Rocket which was amazing. That was the first time I had played a really good fuzz that cleaned up amazingly well when you backed off almost like a good amp. Still, I liked the Rocket for clean but it was more of a pedals kind of amp IMHO. I think the other amps at Kenny's I played that day all had black transformers, as it was after Ken had given up on finding Stancors. I remember he had several amps around that day for me to try.

[doctord02]

The first Express I ever played was a grey (I always assumed Stancor according to Ken) transformer model from the mid 80s. It was and probably still is owned by a guitar/electronics shop in Maryland. The owner of the amp was friends with Kenny from way back. The amp's top was also used in the shop as a cutting board for sub sandwiches! The owner let me borrow that amp for a week and I gigged with it at the well known and now gone "Bayou" club in Washington, DC.

Hah! So you borrowed Steve's (Angela) Express for a test drive? Thats too funny... I had heard from someone else he used the top of the cab as a cutting board.

[M Fowler]

I want to thank all you guys for the very informative data given. I had read the old posts but that only left me wanting to know more. Now I know that the tranny sets I have been getting from Moose are the best I can use. Thanks.

I did with different trannies for my Rocket and very happy with its performance. When I can get some very good NOS tubes it will be even better. But my next build will be an original is I can get Express Head amp. First I have to finish up my asteroid 60 or knwitt will be hot on my butt for not doing so.

Mark

[Moose]

My gut feeling when I later got my Pacific transformer Express was that it was slightly more mid focused, slightly more aggressive, and maybe had slightly less deep lows. I don't remember much difference in the brightness but it was months between hearing the two amps.

Yeah, I did a touch of experimenting and that's close to the difference in the 5200 and 6600 ohm taps. Even with the M27 steel, that was the difference with the M19 giving you more bass whump at the attack, but the higher impedance smoothing things a touch. In M19 you can get some of that bassier sound of the stancor by using a liverpool tranny -- it's not so much MORE bass, but there is a change in character on the low end. Hard to describe as I didn't A/B, I actually swapped trannies on my personal amp.

I am again struck by the fact that these amps are surprisingly picky about subtle changes.

That was part of the reason we had a dual-tap tranny. Original amps had been measured and they had seen 5200 and 6600 ohm primaries, though nobody had pulled together the possibility that one was a stancor, another a pacific, etc... I figured "Let 'em choose for themselves."

For a while, I thought the dude who shared the info with me had measured an Express and a Liverpool, but no. He was right. The stancor was in early express amps as it was a go-to tranny for KF.

as moose said, they are copies of the old stancor units which i believe ken used in some early amps. rh

Thanks for chiming in -- you helped me understand a good deal of this stuff, along with the amp Ritchie built and Glen recorded next the the real deal, and Allyn's work.

[Robbie]

This is great dialogue. I however am still scratching my head as to what OT gets closest to Glenn's tone. One thing that seems clear to me is when I look at the output of a power amp when overdriven, the waveform signature is revealing. I have looked at many Fenders, a couple Marshalls with Mercury Mags and Mooses' vintage Express OT and they are all different. However, you can correlate the tone to the shapes of the waveforms. Therefore, Glenn, I was wondering if you have ever taken a picture of your Express' output when driven hard?

Just a thought.

Thanks,

Robbie

[jaysg]

One 'n', I believe. Glen, not Glenn.

[Moose]

You can fuss over it all you want with waveforms and the like, but Glen used Pacifics in his touring rig clones and got close enough for his ears. You want Franchesca tone, that's the owner of Franchesca and her clone, anecdotal evidence says Pacific will work.

Besides, they're the only other option still in business that I know about. Give 'em a call.

[drhulsey]

... Remember, I'm not a business, per-se...

Moose, you are the busiest "not-in-business" guy I know
I just ordered a Vintage Express OT for my clone.
Thanks for all the work you're not busy doing

[RJ Guitars]

Thank you guys for running this thread and all the good posts... This is very good stuff and reminds me of the old days of AmpGarage.

I've got a couple questions if anyone can help out - Are the Pacific and Heyboer transformers for an Express both 300-0-300 volts? A 2nd relative question - We all know that the AC power seems to be a bit higher today than it was 20 years ago. What impact does the higher voltage have on our efforts to tweak an amp to those original specifications?


On a related note - Has anyone looked at EDCOR transformers? I've had them custom wind several of them in Trainwreck friendly voltages and wattages but it is very early in my use and dispersion of them and I don't know how they might compare to an old Stancor or Pacific.

I've had them wind output transformers for me in 35 watt 4.3k & 5.2K & 6.6K primary impedances. My first impression is that these transformers are very well made and coincidentally they are exactly the same footprint as the Stancor or Heyboer trannies. I've not had a Pacific to compare them with but if they are Stancor copies then the foot-prints should all be the same.

EDCOR is a very small family operation and they tend to work pretty cheap and are friendly toward one-off custom winds. They are here in New Mexico (although I have no other connection to them) and are highly respected by the HiFi guys. They have a real tendency to conservatively underrate their trannies and have an obvious difference in their appearance (Blue Bells) and they never spill an extra drop of varnish anywhere. I also think everything they make uses M6 steel... everything they have made for me has been.

I've made a few amps using Moose's trannies and I think I can say I've never heard a Heyboer that I thought sounded bad... so I think I have some good references to compare to. I am curious if anyone else has used these?

rj

[Moose]

T

I've got a couple questions if anyone can help out - Are the Pacific and Heyboer transformers for an Express both 300-0-300 volts? A 2nd relative question - We all know that the AC power seems to be a bit higher today than it was 20 years ago. What impact does the higher voltage have on our efforts to tweak an amp to those original specifications?

The voltage change was more than 20 years ago. The nominal power change from 110V to 120V in the USA started at the end of the 1950s, so the difference between an amp built in 1980 and today shouldn't require tweaking.

As for the 300-0-300 question, the answer is "No" with a qualification. They are rated differently if you look at the published secondary numbers, but the rating on the Pacific is based on a 115V primary, the Heyboer on a 120V primary. So, even though they are structurally and functionally identical, the published secondary number doesn't match.

In the end, the B+ produced by each will be the same within a very small margin of error.


I've never used Edcor trannies, but I'm sure they're a fine company. The name has been around for quite a while.

However, M6 is not the best steel if you want to chase Franchesca tone. I've got a stancor style in M6 here and it's clear, sounds bitchen with KT66, but the El34 sound is too sizzly and it doesn't thicken up when pushed.

M6 is a grain-aligned steel that is particularly good at resisting saturation, which makes it a technically great steel for audio transformers -- if you're a hi-fi engineer who is looking for clean. To get better saturation performance than M6 -- i.e. more flux with less time in saturation when overdriven, meaning more linear phase and frequency response and less harmonic distortion -- you have to actually go to much more expensive materials like nickle.

However, you can't get the Franchesca tone without the saturation and accompanying alinear response.

So, if you're cloning an express circuit, M6 is bad.

If you're designing your own circuit around M6, or if you're getting Edcor to make you a 470 clone on M6 for the super-super clean Rocket, Then you're good to go.

[billyz]

Moose,
Your history of the Trainwreck Transformers is great stuff. And the difference on voltages and core material with explanations is too cool. More please. This info can be applied across the board for new designed as well.

[M Fowler]

Normally I have been using Moose tranny sets but when I contacted Moose about a Rocket set he was nice enough to tell me to try the A-470S output so I did from Triode Electronics and got an experimental PT from RJ not sure if it is the Edcor he is referring to but was 245-0-245 (490V, 250mA Center tapped).

My Rocket has a very clean and chimey tone not at all like the LP or Express which both have more gain. So I am very happy with it. Heck I don't know what a real Rocket sounds like anyway. It does not have the power of the other two amps but is in a range all of it own for blues, country or cleaner sounds. It is also very pedal friendly.

The longer this tread goes on the more I am learning so once again thanks to all.

Message was edited to correct that the experimental tranny was a PT.

Mark

[soma_hero]

RJ, I'd be interested in getting one of those A470 clones from Edcor on the M6 steel for a Rocket. Was that something you had done spec wise? Or was that just for other amp projects?

[M Fowler]

The A-470S is the Dyanclone OT and not the PT that RJ and I were talking about. I unintentionally called it an OT in my previous message, sorry about that.

We were talking about a different PT using lower voltage. I sure can mess things up if not careful with my wording. I did edit the previous message.

Mark