Power transformer for tweed deluxe

[pdf64]

The 291BEX has a HT winding resistance of 103ohms https://www.hammfg.com/files/parts/pdf/291BEX.pdf
I suppose that power resistors could be added in series with each red lead, eg 68 to 75ohms.

[A.M.]

You do not want to modify the chassis. 291BEX would most likely be fine, but if you want to go with the lower current higher voltage secondary (355-0-355 @ 115 mA, 238.1 ohms DCR), the 290BBEX is the one you want. The primary has options you don't need, but it can be wired for 240V, and the mounting centers are the same as the 291BEX (2.25 x 2.813). The closest one to the original might be 290BBX, with the same HV voltage and current rating, and 204.4 ohms DCR, but it has 120V primary only.

Thanks Martin. But is there any advantage in going for a higher voltage secondary, other than for accuracy purposes? I get that an original tweed deluxe transformer would sag, but why choose the higher voltage option? 90% of the tweed deluxe related threads I've read complain that they their B+ is too high...

[martin manning]

I think people are focused on the sag component, which would be less with the transformer rated for higher current, even if the idle voltage is the same. There is a large voltage drop in the 5Y3, which you would have either way. I don't think it would make much difference, and with the 291BEX you only have one extra lead. Not that that is a big deal, but there isn't a lot of space in the chassis for bundles of unused wire. I look at the current Fender reissues to see what voltages they have settled on. Presumably they have made their choices for overall good sound. In the '57 Deluxe they have 370V on the B+. Those schematics are a good source of voltages in general.

[JPK64]

I chose to go with the lower HV 290BX (US 120V primary). I ended up with a 375V B+1 and a plate voltage of 368V/368V on the JJ rectifier. Sounds great.

[martin manning]

I chose to go with the lower HV 290BX (US 120V primary). I ended up with a 375V B+1 and a plate voltage of 368V/368V on the JJ rectifier. Sounds great.

Perfect!

[A.M.]

I chose to go with the lower HV 290BX (US 120V primary). I ended up with a 375V B+1 and a plate voltage of 368V/368V on the JJ rectifier. Sounds great.

That's cool! The 291bex is the 240v, updated version of your transformer. I should end up with similar voltages : )
In terms of "sag" and overall behavior how would you describe the amp perfomance with that transformer?

[JPK64]

I chose to go with the lower HV 290BX (US 120V primary). I ended up with a 375V B+1 and a plate voltage of 368V/368V on the JJ rectifier. Sounds great.

That's cool! The 291bex is the 240v, updated version of your transformer. I should end up with similar voltages : )
In terms of "sag" and overall behavior how would you describe the amp perfomance with that transformer?

Hi, I'm not an expert on sag even though I know what it is, but I'm not sure what it sounds like while I play. I can only say that the amp sounds great. The glossy tone and touch sensitivity from a Fender guitar like a Strat and a Tele is amazing. Just love listening to the notes ring out together. I consulted many forums and there was one guy that said he's built about 90 of these 5E3 amps and uses the 290BX. Says he does not prefer the higher HV version and I don't remember his exact comment why.

Here's a link to some really good sound clips of a 5E3 with the 290BX PT and 1750E OT (mine has a 1760E).

https://www.tdpri.com/threads/hammond-p ... st-8244683
.