Rate the Express output transformers.

[Mark]

I was thinking perhaps it is time to have a sticky post on the pros and cons of the various output transformers.

Basically, it is Stancor versus Pacific and the various versions of these transformers.

1. Just installed a A8301 in my Express build.
DBeasley started this post.
Edcor output transformer removed and vintage Stancor A8301 installed.

Greater chord clarity with higher gain.
Low end doesn't get mushy with high gain.
Large sweet spot and EQ control.
Note: The amp has PPIMV, Vox treble cut, 150K trimmer resistor to adjust gain, 1 meg resistor across the volume control so it is 500K.

http://ampgarage.com/forum/viewtopic.ph ... er#p384923

2. Grey bell Stancor A-3801 clone by Mercury Magnetics.

These are RJ's comments and not additional comments in the thread, I omitted them as RJ was doing the comparison.

(a) Mercury RJ-3801 sounds great, has clarity and more low end than other transformers.
(b) Pacific 14415 has strong bite and midrange distinction typical of an Express. RJ prefers more chime and bottom end from this transformer.
(c) Pacific 25525 sounded better than Pacific 14415. RJ spoke to a Pacific engineer who said they are essentially the same transformer. The engineer was surprised by the measureable differences between the two model numbers.
(d) Heyboer HTS-9384 sounds great, has a nice balance of tone and harmonics.
(e) Magnetic Components has a good tonal range and breaks up nicely.when pushed hard it does get squishy. It doesn't have the clarity and richness of an old Stancor. The MC output transformer sounded similar to the Ceriatone transformer, and RJ said it was loud and bright.

RJ had said he wanted to test the Marstran output transformer but concluded the tests before doing so.

From my own perspective there were unusual comments in the thread where RJ states he doesn't feel inspired by the Pacific 14415 output transformer and prefers the Stancor A-3801 yet he states the Pacific 14415 is a sonically richer version of the A-3801.

Most in the thread agreed the Pacific did the clean to distorted the best.

https://ampgarage.com/forum/viewtopic.p ... it=Stancor

3. Available, another vintage variant of the Stancor A-3801 O/T.

The transformer in question was a Halldorson S-81 35 watt o/p txer.
Geetar picker pointed out that this transformer doesn't have the 3 layer iron core.
The other similar output transformer is the Triad S-60. Richie points out he thinks the Thordarson 24S57 is similar to the Stancor A-3801.

http://ampgarage.com/forum/viewtopic.ph ... or#p359789

4. Liverpool output transformers

This discussion is largely about who made the first Liverpool output transformer (an amp called Ginger) and what was it's primary impedance.

Largely the discussion is about 5.2K versus 6.6K in the primary if the output transformer.
RJ mentions he used the 5.2K Heyboer transformer with M6 iron and liked it as much as the Dynaco A470 transformer.

http://ampgarage.com/forum/viewtopic.ph ... or#p379547

5. A new source for Stancor A3801 style output transformers

The writer mentions that Chris Merren is going to make an output transformer for the Express, I have never heard anymore about this, though Chris is a nice guy and I have found him to be very helpful in the past. I'll flick him an email and see what he says.

I contacted Chris Merren and this is the reply I received:

I do wind Train-wreck OT's..... Not recently though....
I wound a bunch A-3801 OT's for Kenny Fisher in the late 80's early 90's... when he couldn't source them anymore..
I lived 30 minutes from Kenny in those days...
Kenny wasn't happy with the A-3801...he wanted more presence and more tighter bottom end...
He thought the original A-3801 was bit murky and soft on the bottom...
Eventually I design the Express OT for him....
So I wound exactly 12 transformer variations of the 3801...
After critical listening he picked one that he liked...
This design was sent to Pacific Transformer to wind in higher volume...

https://ampgarage.com/forum/viewtopic.p ... or#p339221

6. Recently picked up "Lori 1985" + Hard Rock Cafe gig.

Glen K discussed the pro's and con's between Lori which has a Stancor and his other Express which has a Pacific transformer. Worth a read if if you are undecided about choosing Pacific or Stancor output transformers.

https://ampgarage.com/forum/viewtopic.p ... or#p197795

7. A-3801 Stancor & Pacific OT's

The thread deals with the frequency response of the output transformer. The frequency response is believed to be between 80hz to 160hz to 16K.

https://ampgarage.com/forum/viewtopic.p ... or#p116437

8. Stancor A-3801 pictures & problems.

Cliff Schect has a problem with his vintage A-3801 output transformer, he said the windings were loose on the transformer, he has disassembled the transformer and has taken photos.

https://ampgarage.com/forum/viewtopic.p ... or#p113621

9. Terra: A Trainwreck Express build with Stancor A-3801.

Cliff Schect discussed and shows pictures of his build. It doesn't have a convention layout.

https://ampgarage.com/forum/viewtopic.p ... or#p104602

10. Stancor - Pacific - Heyboer - Marstran - MM - Edcor - Ceria

RJ tests and discusses the various available output transformers. It's worth a read.

https://ampgarage.com/forum/viewtopic.p ... cor#p99351

11. Stancor 3801 data?

There is a small amount of technical info, not enough for most people I suspect.
There is a reply suggesting the Marstran transformer has been built without the 500 ohm and 250 ohm taps. I don't know enough to confirm this.

https://ampgarage.com/forum/viewtopic.p ... cor#p45615

https://ampgarage.com/forum/viewtopic.p ... ic#p388051

I'll continue to add links as I have time.

[pompeiisneaks]

Stickied, sounds like a great idea to have a collation of this data. Might not be a bad idea of someone in the deep know to setup some kind of table with pros/cons etc.

~Phil

[Mark]

Issue rectified.

I posted a Strat emoji and it turned into a Les Paul. Undeniable proof of the sites mojo!

[BIG Dave]

Chris Merren is very knowledgeable. I had an old Maestro EP1 Echoplex that wouldn’t output. After it going to a couple techs that were stumped, I shipped it off to Chris. Chris diagnosed it and rebuilt it in a week. Reasonably priced too. Highly recommended.

[Colossal]

CURRENTLY I'M UNABLE TO REPLY PRIVATE MESSAGES, THEY STAY IN MY OUTBOX

Mark,

A PM converts from the Outbox (1) to read when the user visits the forum and see that he has a PM and reads it. The PM notification has not been working for probably a year now so guys never know they've been contacted by another forum member until they visit the forum next and notice they have a PM. It's maddening and Phil can't do anything about it.

[Winder]

When you visit the site and you're logged in, there's a notice in the upper right corner that lets you know you've got a message. The the best way, but folks just need to look there and there will be a red circle with a number in it telling them they have that number of private messages or notifications.

[Mark]

Phil had a look at the whole process and it appears. The messages stays in the outbox till the recipient reads it. It is a bit frustrating, I've had issues will email addresses where messages not sent stay in the outbox. I'll remove the message.

[Mark]

Chris Merren is very knowledgeable. I had an old Maestro EP1 Echoplex that wouldn’t output. After it going to a couple techs that were stumped, I shipped it off to Chris. Chris diagnosed it and rebuilt it in a week. Reasonably priced too. Highly recommended.

What were the heads like EP1, I had an Echolette to fix and the heads looked like someone had run a file over them. I had data to align the heads etc, but the heads were just awful.

Here is the thread I started on the echo unit.

https://ampgarage.com/forum/viewtopic.p ... ho#p301829

[pompeiisneaks]

Phil had a look at the whole process and it appears. The messages stays in the outbox till the recipient reads it. It is a bit frustrating, I've had issues will email addresses where messages not sent stay in the outbox. I'll remove the message.

Yup it's definitely annoying, if I could setup email for the domain name, (which I can if I owned the domain) then I could fix it, but I don't so I can't.

~Phil

[beezerboy]

I've been looking but I can't find any vendor that sells the Pacific 14415...

[Colossal]

I've been looking but I can't find any vendor that sells the Pacific 14415...

www.rjguitars.net

[leadfootdriver]

What about the Classic Tone variety? Don't hold back.

[jmrichardson01]

I've been looking but I can't find any vendor that sells the Pacific 14415...

Just a heads up; the Express output transformer part number is 11415 (not 14415). It is being sold directly from Pacific as part number "PAM-OT-30-54R" on their website www.pacificaudiomagnetics.com.

Hope this helps!

JR

[RJ Guitars]

I am slowing shutting down my amp parts sales but have been keeping a few Pacific tranny sets around to go along with the last of everything else I've hoarded for the past several years. In the last few months Pacific has quit responding to my email requests for new transformers so I think this is about the end of the line in offering complete amp packages for me. I did see that Pacific is now selling Trainwreck Trannies direct to the public but I noticed their specifications are not the same as the original Wrecks from the old days.

https://cdn.shopify.com/s/files/1/0519/ ... 1633190816
The output tranny has a 7.5K primary impedance while the originals used 6.6K

https://cdn.shopify.com/s/files/1/0519/ ... 1633189815
The power tranny says it has a 100mA HV tap which was 300mA on the original. It's not clear that the tranny is actually smaller so I'm not convinced that isn't a typo.

The interesting thing on the PT is that it still has that 10A heater tap. It seems like I sorted this out years ago that the original Wreck trannies were cloned from an old Television PT with a few dozen tubes in it - thus needing that 10 amps for all those heaters. It really is way overkill for an Express or Liverpool build for sure but it might be exactly what Ken Fischer wanted.

[Littlewyan]

That's very sad news RJ. Also very odd regarding Pacific. I vaguely recall coming across a site a few years ago which also sold these Pacific Transformers with the correct spec, but I can't find it anymore. You were originally speaking with a very keen contact there weren't you? My memory could be failing me but I thought someone who worked there was very keen in getting the original spec transformers made again, which is how we were able to buy them.