Rate the Express output transformers.

[WhopperPlate]

I posted the same thing in that thread .

[gktamps]

Hence my link to it in this thread, but also asking if anyone has used a 7.5k OT.

[WhopperPlate]

maybe I shall be the first …contemplating making an order …

[RockinRocket]

Rocking Class posted all the files of Kens transformers they could find, 18 or so on here. Sad I lost all of them. They were all very similar, maybe different lead length difference on a lot of them? Non were 7k5.

[WhopperPlate]

Rocking Class posted all the files of Kens transformers they could find, 18 or so on here. Sad I lost all of them. They were all very similar, maybe different lead length difference on a lot of them? Non were 7k5.

too bad they’re gone

Well I guess count me as one more who doesn’t get the whole 7.5k thing …I am still inquiring further with Pacific

[WhopperPlate]

Update from Pacific :

“We were told by Ken Fischer to make a 6.6K ohm transformer for the trainwreck parts. After tweaking the part we did not measure the new impedance so we had just left it at 6.6K.

For the PAM-PT-30-54R, the design does show it's rated for 100mA. This has been working for Ken Fischer and others. If you want us to redesign it for 300mA we can do that.“

[Finom1]

Hello,

Has anyone tried Mercury Magnetics - TW-KF-OT Trainwreck | MISC. | Output Transformer Dual primary — 5200Ω and 6600Ω — 4, 8 & 16Ω taps — Upgrade! From, https://www.mercurymagnetics.com/produc ... ransformer?

Are the specs correct and does anyone know how they compare for sound?

[RJ Guitars]

I've tried the MM and a few others... MM was one of two at the top of my list, but it sounds different than the OEM Pacific. It might not be for everybody because it adds a little something to the traditional Express sound. My ears thought it was not quite as raw and simple as the Pacific, or you could say the Pacific was a bit dull sounding in comparison.

[gktamps]

"For the PAM-PT-30-54R, the design does show it's rated for 100mA.“

Huh. My recollection is that 300mA was the correct spec. Do I have that correct, or are we now getting more confusing info from PacTrans?

$315 for the MM is pretty pricey.

[RJ Guitars]

... My recollection is that 300mA was the correct spec. Do I have that correct, or are we now getting more confusing info from PacTrans...

I'd say absolutely so! However, the 100mA rating might not matter if the wire they are winding with and the leads they use for the HV can handle that load. When I worked with Edcor on custom winds they had a total current/voltage formula that they used with a given frame size. So I could trade some heater amperage for some HV amperage and the only difference was how they wrote up the label. They used the same size of wire for windings and leads in a given frame size. Given the massive over rating of the heater supply on these units there is likely no pain if the HV current demand goes above 100mA.

Working with Heyboer and Edcor I always had access to an engineer that understood transformer designs. I had that for a little at Pacific but the last few years all I can get is a salesperson that isn't really in the know.

Also, this note about Allesandro having a hand in the design is curious. If this is a line of classic guitar amp trannies why would they need design help unless they are new designs?

[RJ Guitars]

I found a few notes... it was a K&M part number that they originally were selling to me as a replacement tranny for Wrecks. I have a copy with a hand written note that says 300mA but I can't say who wrote it. I have a similar spec sheet on the Pacific trannies. Both of them show a 6.6K secondary on the OT's but don't give the current ratings on either sheet. Note that they have a 15 ohm tap on the OT - similar to the Stancor A-3801.

[RJ Guitars]

Here is a look at the Heyboer PT that was used in tens if not hundreds of Wreck clones before the Pacific's became readily available. Note that it actually uses the Pacific part number.

[gktamps]

Also, this note about Allesandro having a hand in the design is curious. If this is a line of classic guitar amp trannies why would they need design help unless they are new designs?

That's exactly what I was thinking as well, RJ.

Here is a look at the Heyboer PT that was used in tens if not hundreds of Wreck clones before the Pacific's became readily available. Note that it actually uses the Pacific part number.

A very familiar document to me. I have built a few with this transfo.

[WhopperPlate]

RJ, thank you for the cache of info!

Concerning Alessandro , from Pacific :

“Since we are just starting into the audio industry after the closure of ClassicTone.
We wanted to make sure we are putting the most authentic vintage replica transformers.
We have George Alessandro from Alessandro Amps testing and verifying our transformers to make sure they sound like the originals.“

Giving the full benefit of the doubt it seems like an honest to good intention…

[Finom1]

RJ,

Thank you so much for posting that and always sharing your wisdom with us.

Could you please help this old timer understand how the Pacific PAM-OT-30-54R with it's 7.5K Ohm will affect the true Express sound I love so much???

I just don't understand!!!

Bless you for sharing your wisdom. You are recording history for us tone chasers and amp lovers:)

Respectfully,
Fino