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Re: Opinions on a 5F2A-5E3 combo

7/22/1999 8:36 PM
fj Re: Opinions on a 5F2A-5E3 combo
thanx Bruce!...gonna see if I can do-it!
And now, a word from our sponsors:

7/22/1999 11:25 PM
connected pins 1 to 8...from (both) pins #4 of power tube sockets I connected 1K resistor to B+...plugged in EL-34 & got some occilation from the socket closest to rectifier...switched tube to other socket AND OK!...fierd it up with 5Y3...readings as # 3 = 321v...# 4 = 292v... # 8 = 21ma...sound OK to you guys?...thanx Bruce!
7/12/1999 8:21 PM

The Hammond 125E is only rated at 15 watts. I would think that running that tranny in a deluxe type setup would be pushing it a little too hard. I am not sure of the power rating on the tweed deluxe, but the blackface is around 22W.  
I think that running the B+ and signal wires through fone single little switch will definetly cause some noise problems. You wouldn't need to run the signal wires into the switch anyway. guitar's usually can't drive the grids positive to start them pulling any current, so I wouldn't think it would be necessary to switch this.  
If I am not mistaken a 125E is only about 25$ at AES. You could just buy two different OT's, and not have to worry about as much of that fancy switching.  
7/13/1999 3:26 PM

I've used the Hammond 125e OT in amps using 5881s and got over 28 watts output at clipping. No sweat with a pair of 6V6s.  
The 15 watt rating is class A single ended (without using the center tap) when the current throught the OT is limited top 80ma or less from 60Hz to abt 15KHz.  
They will work at power levels twice that.  
It is very slighty larger then a BF Deluxe Reverb OT.  
$25 is a great price considering they are about $22 at wholesale!  
7/14/1999 11:46 PM
Gary Anwyl

Thanks for the feedback. It was really valuable. Those are some really interesting ideas for design tweaks for the Princeton and Deluxe circuits. You've talked me out of building the "combo" amp. Now I just have to decide which amp to build first.  
7/15/1999 8:54 PM
Mark Hammer How do you add another power tube to a Class A?
You can tell which way I'm voting for the choice of Princeton vs Deluxe.  
What I'm wondering is how one goes about upping the power of an existing Class A, and what provisions one would have to make in order to plan ahead for it - largely with respect to transformers I would think - or to design a Class A amp that could have varying numbers of tubes installed to yield varying amounts of power. I know that Class AB amps can be backed off from 4 tubes to 2, but a Class A amp could, in theory, be modified a tube at a time...right? Or wrong?
7/16/1999 3:19 AM

What I'm doing is lowering B+ by using a 5Y3 rectifier tube when using the 6V6, then I go to a solid state plug in to up the B+ for the 6L6 or EL34 thereby giving me an increase in output power. I knew I wanted this option when I started building so as you suggest I had to get a power transformer that could supply the heater current required by a 6V6,6L6, and EL34(not all at the ame time). Also when wiring the output tube I had to tie pin 1 to ground since an EL34 doesn't have pin 1 connected to the cathode internally like a 6L6.  
I've had good results and am rather happy at the outcome of mine.  

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