najo49 said:
Which Paramour?
Which power supply?
SR45 amplifier
- Thread starter debk
- Start date
Which Paramour?
Which power supply?
Paul, The paramour 2 and I would like to have main power supply regulated. Or, is it possible to put the soft start paramount kit on the 12at7? I suspect this would be major work. But I was wondering. But Doc I was reading in this thread the possibility of a board being avail. on a limited basis w/0 a manual,or am I mistaken.Jann
najo49 said:
Why? and why?
The soft-start is technology implemented to stabilize direct coupling, which the Paramour does not employ.
Main power supply regulation and 2A3 operation is not possible on the PT-2.
While you "could" install the soft-start upgrade into the Paramour II, there are no instructions for this, and any installation errors will be your sole responsibility to troubleshoot.
Paul Joppa
Moderator
@najo49 -
What we have been using for regulated high-voltage power is a shunt regulation scheme. This requires both more voltage and more current from the power supply, as well as adding the regulator circuit. That's the reason why the old SR45 uses a 45 - the tube itself needs less voltage and less current than a 2A3, thus the Paramour power supply could power a shunt-regulated 45. It also explains why you can't easily convert a 2A3 amp to regulated operation.
Because I am not happy with the design of the original SR45, I have asked Doc B to not sell anymore of the boards. Instead (as described in various places in this long, rambling thread!) I am working on an SR45 design done right. When we have a working prototype, I'll start a new thread.
The Paramour II, however, does have enough power supply headroom to run a shunt-regulated driver stage (with unregulated output stage). The easiest way to do this is to use the Paramount soft-start upgrade kit. There are no explicit instructions available, but the conversion is similar to that for the Paramount. You must use the (included) 5670 tube instead of the 12AT7.
What we have been using for regulated high-voltage power is a shunt regulation scheme. This requires both more voltage and more current from the power supply, as well as adding the regulator circuit. That's the reason why the old SR45 uses a 45 - the tube itself needs less voltage and less current than a 2A3, thus the Paramour power supply could power a shunt-regulated 45. It also explains why you can't easily convert a 2A3 amp to regulated operation.
Because I am not happy with the design of the original SR45, I have asked Doc B to not sell anymore of the boards. Instead (as described in various places in this long, rambling thread!) I am working on an SR45 design done right. When we have a working prototype, I'll start a new thread.
The Paramour II, however, does have enough power supply headroom to run a shunt-regulated driver stage (with unregulated output stage). The easiest way to do this is to use the Paramount soft-start upgrade kit. There are no explicit instructions available, but the conversion is similar to that for the Paramount. You must use the (included) 5670 tube instead of the 12AT7.
caffeinator
New member
If you just want a kind of dumb soft-start, it might be possible to implement using an Inrush Current Limiter in the incoming mains power. Note that this will somewhat slowly ramp all power, filaments and B+ alike - not sure that's what you're after.
See the linked datasheet for more info. I've used the CL-90 variety in kits for small push-pull tube amps, typically in the return leg from power trans primary to neutral (w/ hot switched upstream of power trans primary).
http://www.mouser.com/ds/2/168/920-325D-LR-245176.pdf
See the linked datasheet for more info. I've used the CL-90 variety in kits for small push-pull tube amps, typically in the return leg from power trans primary to neutral (w/ hot switched upstream of power trans primary).
http://www.mouser.com/ds/2/168/920-325D-LR-245176.pdf
caffeinator
New member
Well, if I'm doing something that Xavier is doing..well..I'll keep doing it.
Garcon! CL-90's, all the way around!
Garcon! CL-90's, all the way around!
howardnair
New member
output transformer question-i am finally getting around to building the SR45-i am laying out on posterboard my wiring diagram-this concerns the MQ exo45 output transformers-there are 4 wires 2 on either side-i pair is red and blue and the other pair is black and clear--the red and blue read .436k-and the black and clear read 1 ohm-so the red and blue go to my outputs -i will guess that red is positive -how may i ck this to be sure--and on the black and clear wires one wire goes to the plate via the coupling cap the other to the junction of the hum pot, cathode bypass cap and cathode resistor-does it matter which wire goes where?
thanks howie
thanks howie
howardnair
New member
ok so the side with the large resistance is the primary side-the exo45 is handwritten--but there are no dots-on the primary side both red and blue come out of the transformer at the same distance from the coil--on the output side one wire obviously comes from the inner part of the coil-i will post on the mq site thanks--howie
howardnair
New member
aaron -thanks-i should know these things by now-i still am not certain what lead goes where-i suspect that the red to the plate and blue to ground and clear to positive and black to neg-being they are 550 for the pair i would like to be certain-i am surprised how much real estate i need for this-output transformer,large plate choke, triad power choke,grid choke and output trannie times 2 -i am using jensen radial style caps which are large -a mundorf m-lytic cathode bypass cap-again times 2 -plus all the other things needed-rt now it is all layed out on 1 piece of poster board-i am not sure whether it will be 1 amp or 2--this is my first scratch build-so it is fun but i am a little nervous-if put on one chassis are there any special cautions between the left and rt sections-
Paul Joppa
Moderator
My mnemonic is the "blue plate special" - an old diner term that has stuck in my head. Blue to the plate (i.e. high AC signal voltage). For series feed transformers the red goes to the high voltage supply; for parallel feed it goes to AC ground; in this circuit that would be the cathode. There is a parafeed cap in one of these lines of course! Note that whether the red lead goes to B+ or to ground, the important thing is that it has near zero AC signal voltage.
Grainger49
New member
Paul,
From what I know of transformers it will work either way but swap absolute phase on the output.
However, wiring it as it should be yields lower noise.
Is that right?
From what I know of transformers it will work either way but swap absolute phase on the output.
However, wiring it as it should be yields lower noise.
Is that right?
Paul Joppa
Moderator
I don't know all the reasons for choosing a polarity, but I'm pretty sure there are more than one.
howardnair
New member
ahhh!!-Paul--the blue plate special it is!!-mike got back to me and the blue goes to the plate and red to ac ground-and black is ground on the secondary-and here is a little read on the blue plate special
http://en.wikipedia.org/wiki/Blue-plate_special
http://en.wikipedia.org/wiki/Blue-plate_special
Grainger49
New member
Howard,
Now Paul should reveal what BPC stands for.
He has before, it isn't a secret but it is funny and appropriate.
Now Paul should reveal what BPC stands for.
He has before, it isn't a secret but it is funny and appropriate.
