Best Output Transformer

[Robbie]

Hi Folks,

I've been listening and reading a lot about output transformers and have come to the conclusion that amps that use power amp distortion rely to a large degree on the OT for their tone. I am using a Toneslut OT in my Express Clone. While it sounds good, it doesn't exactly match the dynamics and harmonic content that I hear on Glenn's clips. So the question is, which aftermarket OT gets the closet to the original Express tones?

Thanks,

Robbie

[Moose]

You using the original spec, or the vintage spec tranny? I don't remember when I sent you yours, but I added some new stuff to the line at the end of the year.

The vintage spec is identical to the Pacific in Glenn's amp -- on M19/26 steel, same lams, same wind, same tap, etc. The difference is noticable in the feel of the amp, especially in the ease of sustain, as well as in the midrange focus and distortion. It's smoother vs. the crunchier distortion on the original M27 version.

So, if you want Franchesca tone, the closest tranny I have is the new Vintage spec. The other choice is to chase down a tranny from Pacific, which is what's in Glenn's original amp.

[Robbie]

Hi Moose,

Thanks for the response. I remember looking at the various options on your website and I ended up settling on the vintage OT. When I scope the output, at the onset of OD I see:

a.) Attenuation of low end response via the falling trailing edge of the waveform.
b.) A duty cycle shift resulting in even order harmonics
c.) A degree of cumulative sag as the transformer is driven hard.

The tone is 'smooth'. In listening to Glenn's clips, I thought there was more of a crunchy thing happening when he was doing the bar chord work that I'm not able to duplicate.

How does your other transformer behave as compared to what I have described above?

Thanks,

Robbie

[billyz]

Are you using the same guitar, same speakers, etc. Point is Transformers are important but there are many ingredients to the tone. Tubes, cables, The PLAYER. The room, the mic, ad infinitum.

[Moose]

I can't really diagnose for sure, but the only more authentic transformer is a Pacific and it will be ostensibly identical to the Vintage Spec, though you might hear a difference. That's what Glenn used in his clone, and why I switched steel to match it.

At this point, the other question that comes to mind is your tube complement. The "crunch" value of the amp -- other than trannies when overdriven -- comes in large part from the second preamp valve. I have a warm-sounding Bell that makes my express a blues amp with warm, wet, and creamy distortion, and I have a black-plate triple mica that elicits thoughts of a JCM800 with all the crunch in the world.

Glenn's pretty picky about his valves, including the power tubes he uses (one of the GT line, ping him and he'll tell you specifically) and that might also get you a little closer.

These are picky amps. They are a beast to tube, and they are really fussy about some simple things, but that's where the tuning comes in. Picking valves and, if you so choose, fussing with the filter in the clipping stage to further refine your response.

So, in summary:

- Check your preamp valve
- Check with Glenn on his poweramp tubes
- The most authentic OT would be from Pacific to the same specs

[geetarpicker]

On my CD I was using Siemens EL34s, which I guess are aka RFTs. However more recently all my clips are using the GT EL34Ms biased at about 45-48ma. All of my Express clips on youtube are using old Sylvania 12AX7s, though on my CD I may have used other preamp tubes on different tracks. I use to use Tung Sol 12AX7s a bit when I had a few good ones. In my amps I find the Sylvanias have deeper and tighter lows.

Yes my original TW has a 6.6k primary Pacific OT (and a Pacific PT) and so do both of the clones I built. My original and clones both run around 417B+, here where the wall voltage runs a little high at about 122-125v.

On another note a crucial thing for me is the bright switch. I always use the full 500pf position, and can't really get my tone without it even by tweaking the knobs to compensate. The 500pf cap is always switched on. However it's almost a little too much so I mellow it back a tad with two 18' Mogami cords in series, and old G12M speakers which are a bit dark compared to other lower wattage speakers. Way darker than typical new "greenbacks", and a little darker than the M75 Scumbacks but they are quite similar. On the cord note my original Wreck sounds pretty darn nasty with a short cord, it just needs the loading of the longer cord. I tried small caps on the input using a shorter cord, but the longer cable simply sounds better. The bright caps seems to really help the clean tone shine when you back the guitar down, and the amp doesn't really seem to clean up as well (or "sound" clean) without it. The extra jangle helps the clean tones to stay clearer, and when you crank the guitar the amp seems to compress the extra top away just enough. Probably part of that IS the output tranformer saturation rounding off the highs just a tad.

My Strats have Fralin vintage hots for pickups, and my old Les Paul has stock original PAFs. My strats are wired with a jumper on the 5 way switch, so that the 2nd tone control works on both the neck AND bridge positions, and the 1st tone works on the middle pickup. This does mean that when I use the bridge and middle together OR the neck and middle together both tones are functional but do the same thing. The side effect of the bridged wiring. I use a fairly large cap in the strat and with it wired this way there is some extra darkening going on in the guitar at least in those two pickup switch positions as both tone pots load it down slightly more than stock wiring. I didn't realize this until just recently when I put fralins in my relic and it was noticably brighter than my Callaham, until I jumped the tones together.

I guess I'm saying it all plays a part. I hope that helps! GK

[Robbie]

Thanks everyone for the feedback.

I have tried an array of speakers and tubes, but the most interesting thing that Glenn pointed out was his use of the (2) 18' cords in series. I ran a couple calcs and came up with the following loading numbers for the cables then ran a quick simulation to see what affect the caps would have on the resonant freq of a humbucker having an Rs of 10Kohm and L = 5 H. These are rough approximations, but are interesting.

I looked at the cable having a range of cap anywhere between 20pf/ft versus 50pf/ft

a.) 36ft x 20pf/ft = 720pf >> Fres = 2.8Khz
b.) 36ft x 50pf/ft = 1800pf >> Fres = 1.8Khz
c.) 6ft x 20pf/ft = 120pf >> Fres = 4.5kHz

The slope of the cut-off is -12db/oct so I could imagine the cap loading really making a difference in tone.

I will have to try this!

Thanks Again,

Robbie

[geetarpicker]

My mogami cables measure about 600-700pf per cable. I recently measured the single old no name 40' cord that I used on my CD and it's around 3500pf! These days I find the mogamis sound nice and my old 40' cord to have too much of a mid spike to my ears. I guess when I mixed my cd I made it work in the mix. Either way, Ken told me he had even made boxes for folks with a rotary switch and multiple small caps. Many details in this thing about tone.... GK

[Moose]

Glen,

In case I haven't said it this week, you're always remarkably helpful. It is much appreciated.

[M Fowler]

Moose,

Did you compare the constuction of the Pacific to come up with the Vintage Spec series that you have now? I would imagine trying to find a Pacific would be darn hard to do. I see that there is a Pacific transformer company is that the same company but they don't sell this type anymore?

I have more questions than I do answers, unfortunately. I need to order another tranny set from you soon this time around will be for an Express and yes I want it as close as I can get to an original spec.

Not that I want a Mercury Magnets tranny Moose, it is just that you know your trannies. Do you know if those guys at MM ever cloned an original Pacific? They advertise to send your vintage in and they will clone it.

Mark

[Colossal]

I see that there is a Pacific transformer company is that the same company but they don't sell this type anymore?

Mark, for what it's worth, I called Pacific (1-800-325-0501) a while back when I was working up a parts list for an Express. I gave them the original Express transformer part numbers that I think Glenn provided. They said they could still make them; here are the quotes I was given:

PT 25475 $98.29
OT 25525 $79.15

Do you know if those guys at MM ever cloned an original Pacific? They advertise to send your vintage in and they will clone it.

I asked with Paul Patronette at Mercury about this as well and he said they did have part numbers for Express iron. I think they were TW-KF-PT and TW-KF-OT or something close to that. They were <i>quite</i> a bit more than Moose's Toneslut or the Pacific Iron but, if I recall correctly, were supposed to be clones of original Pacifics.

Dave

[M Fowler]

Dave,

Thanks for the information. I am very happy with Moose's Heyboer sets and price but just wanted to know more about what happened to Pacific, if they are still building how come we aren't using those trannies and also why not using MM trannies.

This is all interesting and I have read the old posts back to 2005 but I can't remember everything I went over.

Mark

[Moose]

I would imagine trying to find a Pacific would be darn hard to do. I see that there is a Pacific transformer company is that the same company but they don't sell this type anymore?

I can get my hands on Pacifics, easily. Allyn, your glorious forum sponsor, has a good relationship with them and he, as well as a few others, have really helped us out with tranny info in the last year.


Anyway, I think I need to give the history again. I apologize for the thread hijack.

First -- the origins of KF's preferred trannies (rockets not withstanding). They're all "clones" of the stancor iron. Wound the same way, but with different primary impedances. The Pacific and Heyboer are both from KF's line card -- I don't know anything about the mercury stuff.

After stancor when out of business and he couldn't buy their stuff off the shelf anymore, KF used several winders, and they all wound to the same specs. He'd change impedance and steel on occasion, to suit the work he was doing.

The current heyboer wind came from Ken's line card. Originally, we thought they were M6, but that was because the line cards got confused between one that was ordered for a Hi-Fi experiment (on M6 steel) and something that a previous seller had done, and we took a guess at the correct steel.

The problem with the original guess was that we knew M6 wasn't it, and the person who did the research refused to talk. I can't say more about that. Additionally, there was a lot of misinformation and hokum floating around about all that. Some of it purposely fed to confuse the builders here, some of it just the product of the rumor mill. So, we took our best guess -- actually I took that guess -- and guessed wrong with M27. The amps sounded cool as hell, but not as marshally as the Franchesca tone that most people want now that Glen's clips are available.

Anyway, fast forward 3 years. Once we had our nose in Franchesca, and once Glenn and Allyn did some work, and Glenn built his clones, etc. etc... we learned about the steel in an express (M19/26). That was just last spring, so I experimented through the summer and fall (I order by the palette, so I only get trannies only a few times a year), and when I was convinced I switched steel.

The reason I don't carry Pacific is, simply, they wouldn't respond to me when I asked. Not "no" or "sure for a lot of money" but dead silence. SO, I worked a deal with Heyboer. Pacific has become significantly more forthcoming in the last year, but 4 years ago they didn't want to talk to me and Heyboer has been fabulous.

That said, if Heyboer couldn't wind them the same and make them sound the same, I'd have gone back to Pacific and tried again. But the Heyboers are good now that I've corrected the steel, so I haven't tried to work with Pacific.

Remember, I'm not a business, per-se. This all started when there were about 20 of us with completed wreck-like amps and about 100 forum members, total. No wreck owners were sharing info like Glen, and Heyboer was really complaining about one-off orders since the previous reseller had quit carrying wreck trannies. This is like a group-buy that has gotten way out of hand!

Anyway, I have to pick and choose my battles if I want to have stock on hand to ship out right away. Especially at the current prices as cost on power trannies has climbed dramatically in the last 18 months. I'm already to the point where I have to ship truck-freight, and I carry international versions of the power trannies, and now I have separate line items for liverpool and express so the express tranny can be EXACTLY the formula in the real amps -- even down to the single tap.

So, that's how this all came about.

Wow -- a lot of typing. Again, sorry to hijack the thread.

[Richie]

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.

[rhinson]

i had heyboer wind a batch of express trannies to exact specs a couple yrs ago (6.6k pri only and m19/26ga steel) for some builds and compared them them to the couple of pacific units i purchased a yr or two before that. in the same amp i could not tell the difference between them. i ended up just leaving the heyboer in the amp.

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