Ain't it good to have too much B+? lol.
I am having a hard time to get a proper PT. I either have all the windings I need but not ennough B+, or I get overboard and end up with something ridiculously too strong.
I am starting to think about putting the front end (and maybe add a pre-amp while I am there?) in a separate box... although I really wanted to have all in a single chassis.
I never used a preamp. are those overrated?
[to be honest, I'd rather just find someone who sells an appropriate power amp]
I am having a hard time to get a proper PT. I either have all the windings I need but not ennough B+, or I get overboard and end up with something ridiculously too strong.
I am starting to think about putting the front end (and maybe add a pre-amp while I am there?) in a separate box... although I really wanted to have all in a single chassis.
I never used a preamp. are those overrated?
[to be honest, I'd rather just find someone who sells an appropriate power amp]
Don't I need the 6.3V to be center tap to avoid hum? (maybe I misunderstood the concept here, if it is not required, I'll dig again trough the edcor site...)
Also, I want to add a front-end with display. I'll suck up about 10-20mA from B+ for the display, and require a 5VDC for the electronics controls (I want to remote modify digital potentiometers for volume) - can I add a rectifier out of the same 6.3V as the heaters without having induced noises?
[edit] I see you posted the XPWR064-120 while I was writing. This is one I coloured as "interesting" - I am glad to see I am making sense in my searches...
Thanks!
Also, I want to add a front-end with display. I'll suck up about 10-20mA from B+ for the display, and require a 5VDC for the electronics controls (I want to remote modify digital potentiometers for volume) - can I add a rectifier out of the same 6.3V as the heaters without having induced noises?
[edit] I see you posted the XPWR064-120 while I was writing. This is one I coloured as "interesting" - I am glad to see I am making sense in my searches...
Thanks!
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Some circuits need to elevate the 6.3V heaters to meet heater-cathode insulation requirements (again, explained well in MJ's book). In that case I would not use the 6.3V for a logic board. However, this "DIY Push-Pull (PP) 6V6" amp does not require this. If you build the low voltage supply using "Ultra-fast" or "Schottky" diodes and/or use snubbers, you don't really need to worry about it. SY was referring to the diodes on B+ itself inducing switching noise into the heater supply via the transformer. He has a point, but frankly most amps out there work just fine. In this amp in particular, such noise would be all common-mode and would mostly cancel-out.
What is your "display"?
What is your "display"?
I am (slowly) working a front-end control system that would have volume/tone/balance knobs, IR remote control (hopefully) and display values via nixie tubes. (I love the look of nixies!)
It will use a microcontroller and some modern electronics, to control a set of digital potentiometer to the amp. I figure the nixies will look very good with a tube amp, and the whole thing will give modern functionality without changing the end result of the input signal (beside volume/tone adjusting it).
The nixies will require to tap on B+ to get about 180V at maybe 10-20mA, and the microcontroller, power transistors and IC to control the knobs and nixies will need 5VDC (still uncertain how many mA, but won't be huge). The precision of the 5VDC is not super critical, I could run as low as 4.5V I guess.
Its a good thing if I can pull it all from the same 6.3V.
Do you think the XPWR064-120 would be powerful ennough?
It will use a microcontroller and some modern electronics, to control a set of digital potentiometer to the amp. I figure the nixies will look very good with a tube amp, and the whole thing will give modern functionality without changing the end result of the input signal (beside volume/tone adjusting it).
The nixies will require to tap on B+ to get about 180V at maybe 10-20mA, and the microcontroller, power transistors and IC to control the knobs and nixies will need 5VDC (still uncertain how many mA, but won't be huge). The precision of the 5VDC is not super critical, I could run as low as 4.5V I guess.
Its a good thing if I can pull it all from the same 6.3V.
Do you think the XPWR064-120 would be powerful ennough?
Well, the four power tubes will typically be setup for 30-35mA each. The 6SL7 will probably be something like 2-3mA per plate, so that's ~150mA at idle for the amp. At full output it will be more like 200mA from the B+ supply. You'll need 3A for the heaters. It seems like you have enough headroom.
That sounds like a good plan too. Maybe run it from a wall wart to give yourself some flexability and some isolation. One thing sometimes not appreciated when beginning with valves/tubes is that solid state is very very fragile, and easily damaged by the tiny transients in valve gear. Leakage to filaments is a classic potential problem, so sharing the filaments' transformer windings for the solid state stuff is a false economy.
All good fortune,
Chris
All good fortune,
Chris
Do you think I should simply run it from a wall wart in the end? I could technically add a plug to the amp before the PT and plug the wallwart there. It could even be controlled by the same power switch. I was somehow wanting to make a "final" product, but if I fry something or induce noise, I might be wasting time trying to make everything work on a single cord...
(well, its not wasted time, I am learning a lot about power transformers!)
(well, its not wasted time, I am learning a lot about power transformers!)
I suffer the same affliction, to want to make everything polished and professional. It's sometimes at odds with the other goals of a learning project. But often, breaking a project down into managable and testable steps is most important, and also allows for changes as we learn our way along.
Maybe leave enough room in the chassis for a small separate power supply, just in case?
I know one thing for absolutely sure - there's *always something* that wants to get itself into any available space!
All good fortune,
Chris
Maybe leave enough room in the chassis for a small separate power supply, just in case?
I know one thing for absolutely sure - there's *always something* that wants to get itself into any available space!
All good fortune,
Chris
I might leave ennough to add an edcor XPWR083A-120/240 to act as plan B (or C?) ifever the original PT cause issues.
I also want the chassis to have enough room for maintenance. I am still recapping my philco radio, and there are areas that are just annoyingly tight, while other areas are about empty.
which leads me to another question - perhaps I should post it on another thread...?
how do we select the size of the chassis? I am wondering if I should make a wood/metal chasis, or purchase a nicely build/folded together all-metal one, or whatever. I have no prior experience in selecting chassis, I don't know what to look for... Are there some kind of online guides about that I could read?
I also want the chassis to have enough room for maintenance. I am still recapping my philco radio, and there are areas that are just annoyingly tight, while other areas are about empty.
which leads me to another question - perhaps I should post it on another thread...?
how do we select the size of the chassis? I am wondering if I should make a wood/metal chasis, or purchase a nicely build/folded together all-metal one, or whatever. I have no prior experience in selecting chassis, I don't know what to look for... Are there some kind of online guides about that I could read?
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