New 80 Watt Wreck done!

[Allynmey]

The 10 amp filaments was nothing more than overbuilding. This is a touring amp and it was built to last. 1/8" thick chassis, Stainless hardware, 2W pots, 1/8" thick G10 boards...etc.

[M Fowler]

Thanks Allyn it is a nice amp and one of those chassis would have been nice to get ahold of along with the Pacific tranny set.

Well if you take into consideration that I would be up to 7A and with safety to 8A it is not unrealistic for the 10A, it just through me at first. The 3.3k OT has me stumped though as usually it is from 1700-2200 for that much power.

Mark

[dave g]

The 3.3k OT has me stumped though as usually it is from 1700-2200 for that much power.

I think that the 3.3k primary comes from the fact that the Pacifics Ken used were 6.6k, so for 4 tubes you would naturally divide the primary impedance in half.

If you read the EL34 datasheets, you'll see that the output impedance of two tubes in AB1 varies wildly depending upon the operating conditions, from around 2.8k all the way up to 11k.

Old Fender and Marshall specs aren't gospel. Leo and Ken Bran just used whatever they could get cheap...

[M Fowler]

Called in and re-ordered the transformers were not at production yet.

Ordered 315-0-315 400mA 6.3V 10A PT EDITED VOLTAGE

Ordered 412v; 1.7k 4,8,16 rated 100 watt OT

Now I will wait and see how those will work.

Mark

[M Fowler]

Just incase anyone else is building this amp and wants to go 80-100 watts using Edcor trannies.

The Edcor tranny info is

XPWR130 630v CT 400mA 6.3v 10A PT $79.73

CXPP100-MS-1.7k 100 watt 1700 ohms to 4, 8, 16 $92.87

Mark

[guitardude57]

Hey Mark,

Thanx for the tranny info. It is still a couple weeks out for me to order, but I will. Are you having any type of color coding with the wires? Or just stock?
Mike

[M Fowler]

I have issues with my Vista software so no excel data sheet.

BOM for 80w Express If I get my software figured out I could make BOM with mouser part numbers and Hoffman source, etc.

Mark

[M Fowler]

Here is the transformer charts.

[guitardude57]

oooooppppps

Isn't the OT supposed to be a 3.3K? Might minimize the balancing act.
Oh, what is the turn time on Edcor being quoted? Mike

[guitardude57]

OK, your info on the tranny diagrams just popped up......

[M Fowler]

Turn time is 4 weeks so if one needs to change something always call in rather than email.

Allyn is using 3.3k custom Pacific tranny and I have not found anything close in a 80 watt rating. So I did what most have done used the 1.7k to 2.2k primary.

Mark

[RHGraham]

what about the hammond 1650KA... 3.4 k, it's only rated for 50w, but I would think it might be alright in this app perhaps? Or is that pushin it for a hammond tranny...

[M Fowler]

I had looked at the Hammond 1650R 100 watt 5K 4, 8, 16 but it didn't seem right to me wasn't sure what voltage it was intended for.

Mark

[Allynmey]

If you are looking to keep that TW Express sound and feel with increased girth and chest punching power, I would suggest staying with the original specs. TW's are tough enough to balance stability when you use the correct parts let alone changing impedances and voltages.

PT sec. should be 300V-0-300V

Just my 2 cents

[M Fowler]

Yeah but Allyn I don't have an inside with Pacific or Heyboer or anyone else and Edcor is very reasonable to work with heck I could have requested a custom from them but decided to use something they have already engineered as not much they do is stock as far as guitar tube amp trannies.

So I went with 315-0-315 as close as I could get to your tranny and I have not seen any 3.3k 70-80-90-100 watt OT trannies.

Thanks for your help it is very appreciated.

Mark