Hoffman Amplifiers Tube Amplifier Forum
Amp Stuff => Tube Amp Building - Tweaks - Repairs => Topic started by: bakerlite on September 29, 2014, 06:49:01 am
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Hey folks,
Long time no pester with questions aye?! Chopped the top of my index finger down to the bone so tinkering with amps been on the long finger (pun intended)
So at last playing again after months of physio and it follows its time to tinker again.
Anyway enough with the preamble...
Got a few gigs at the end of October I would like a 5e3 for. I have a gutted valve junior head and I am going to try and cram Doug's 5e3 turret board in there.
My stumbling block is that I need an upright transformer for this build that's not too large....
Does anyone have any ideas? It needs 6.3v and 5v taps as well as the big juice.
Speaking of which Does anyone know if Doug's layout is intended for a particular voltage ? There are so many laydown transformers for this amp varying from. 260-0-260 right up to 380, I think I should be shooting for 325-0-325 but if anyone knows different can they steer me straight?
Also if anyone else has fitted 3 extra sockets yo a vj chassis it would be nice to think it has been succsesfuly done as it sure measures up close....
Cheers
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I need an upright transformer for this build that's not too large....
Hammond 270FX would be my first choice because I've used this PT in several builds and know what to expect from it. It will give you about 350V B+ loaded with a 5E3 circuit. The 270EX would also be a good choice.
For a little more B+ I would use the 272DX or 272FX.
I kinda lean toward the 270FX or 272FX because they have a center tap on the heater winding. Here's a link...
http://www.hammondmfg.com/263.htm (http://www.hammondmfg.com/263.htm)
Speaking of which Does anyone know if Doug's layout is intended for a particular voltage ?
Doug's layout uses 475v filter caps. It will handle any voltage you are likely to throw at a 5E3.
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Awesome. So 550ct.... I was way off thanks.
Also I am euro voltage so I guess the http://www.bluebellaudio.com/transpowerPDFs/EDB370FX.pdf (http://www.bluebellaudio.com/transpowerPDFs/EDB370FX.pdf) 370fx is the one to go for
Its nice and small too.
Cheers
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I've had great luck with the 5E3 circuit and the classictone 40-18066 330-0-330. Lots of B+, more than the original. It's an upright. It might fit the bill.
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I am in two minds about the b+...
I wonder the difference between using a 275-0-275 and a 330-0-330
I am in no way knowledgeable enough to know what affect that would have on the sound of the amp. I'd love to know!
Got my parts ordered from Doug so just gotta bite the bullett on the power transformer and tubes. Thinking new issue tung soo for Tue 6v6 seem a good bet . I have had rotten luck with EH 12ay7's though and its arguably the mist important in this circuit....
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The lower voltage PT will give a more "brown" sound, with not as much headroom.
FWIW, my 5E3 uses a 330-0-300 transformer from a reissue Deluxe Reverb. It's small enough that the B+ is sucked down to 340VDC using a NOS 5Y3. This same PT produced 420VDC using a 5AR4/GZ34 in a fixed bias Deluxe Reverb circuit.
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Which of the two ?
330-0-330 or 300-0-300 ?
Franco
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Well I took the advice and sprung for the 275... Will report back....
Build thread pending! Thus things gotta be ready for 23rd Oct..