5e5-a build suggestions

[mark enger]

Ive built a few 5e3 with 6l6 type 5e5, now i was wanting to try the fixed biases 5e5-a, i was gonna do them in head type chassis not combo, ive never played the real fender 5e5-a was wondering how useful the tb presence tonestack is? i was also thinking about using a 5th input like my sunn model t, any suggestions woulld be helpful thanks mark

[Structo]

Well just as the 5E3 Deluxe the way the first tube is wired will make the volumes interactive.

The 5E5a amp is the Pro as you know, so about double the power of a Deluxe.
The TB controls are pretty crude as far as tone stacks go but it probably adds to the Tweed tone these amps have.

The Pro also adds negative feedback in the way of the Presence, but with a NFB resistor of 100K it isn't going to affect it too much.

It's probably a very cool amp to have.

See the Weber 5E5a to see how to implement the adjustable bias mod.

https://taweber.powweb.com/store/5e5a_schem.jpg

[mark enger]

Thanks structo. I was thinking about running 6550 as i have a sextet of good ones, Can i simply sub the 6l6 with 6550? Would i need a different ot? Ive tried kt66 in my cathiode biased 5e5 and they sounded great, Ill be running about 425v on the plates.

[renshen1957]

Thanks structo. I was thinking about running 6550 as i have a sextet of good ones, Can i simply sub the 6l6 with 6550? Would i need a different ot? Ive tried kt66 in my cathiode biased 5e5 and they sounded great, Ill be running about 425v on the plates.

Hi,

How much heater current does your 6V3 secondary have? The 6550 is a hungry tube current wise, 1.6 amps, I have measured as high as 1.8 on some tube samples! The 6550 is a more linear tube, (takes longer to break up), great for more head room, clean sounds. The 6550 won't be any louder in the circuit than a 6L6 or KT66 (1.4 amps heater current BTW), just a different tone.

I wouldn't worry about OT transformer impedance, the tubes don't, an OT for a Tweed Pro is fine, the secondary options might be worth contemplation if you are making a head.

My son owns a 5E5-A (with Octal Preamp tubes, factory original one of only two he has seen), the T-B pots work very well. The V2 has a feedback loop and the pots are fed from a CF. The presence works well, too, and a several of magnitudes better than Fender's original RI Tweed Bassman presence knob.

Comparing essentially the same circuit/tone stack in a 5E6-A side by side with a 5F6-A with the typical Fender tone stack (both vintage amps), I found the F6-A settings TMB to be affected more by interaction compared to the E-6A stack. The other curious phenomena I noted was the volume setting on the channel not plugged into would audibly change the tone when rotated either CW or CCW on both amps. I recall similar on my sons amp.

5E5-A is a great circuit, and its cousins the 5F4 Super (4.7 Mega Ohm), and the 5E7 bandmaster (10 Mega Ohm) only differ in a component change in the V2 feedback loop (5E5-A, 5 Mega ohm) and the Tweed Supers and Bandmaster have 56k feedback resistors to the Pros 100k.

Best Regards,

Steve

Steve