| Sherman |
I'm putting together my list of "goodies" to try a pair of tube buffered NIGCs. My plan it to build two monoblocks so I guess I'll be wasting half a tube but that's OK.
Does anyone have any thoughts on this for a filament transformer- http://www.jameco.com/cgi-bin/ncomm...ys=503;528;781;
(Part no- 102162 in case the link doesn't work.)
And this for the higher voltage (+-35VDC)
http://www.jameco.com/cgi-bin/ncomm...ys=503;528;781;
(Part no- 102103).
They seem to meet the voltage and current requirements and I would be using one of each for each channel.
Also I'm looking at this one to supply the LM3875TF-
http://www.allelectronics.com part number TX-245
(I can't ge the link to copy correctly.)
Any thoughts before I plunk down my cash... er, plastic? |
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| planet10 |
| quote: | Originally posted by Sherman
I'm putting together my list of "goodies" to try a pair of tube buffered NIGCs. My plan it to build two monoblocks so I guess I'll be wasting half a tube but that's OK. |
Just wire then to use different halves of the tubes... when one half wears out (ie probably when you are old & grey) you can swap the tubes across mono-blocks and use the other half.
| quote: | | Does anyone have any thoughts on this for a filament transformer- |
Should be more then enuff
| quote: | | And this for the higher voltage (+-35VDC) |
Beefier than what i was planning on using... i was going to run them at a higher voltage thou.
| quote: | | Also I'm looking at this one to supply the LM3875TF |
with +/- 12V you are going to be down around 15-16V rails... something closer to +/- 18V would give you more power.
dave |
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| Sherman |
| quote: | Originally posted by planet10
...with +/- 12V you are going to be down around 15-16V rails... something closer to +/- 18V would give you more power...
dave |
Dave,
Thanks for the feedback!
I actually thought about using a three pole two position rotary switch to change tube halves! :D Probably won't though!
For the GC power trafo I was planning on using the CT as 0 volts and wiring the outside to the bridge and getting 30VDC or so after rectification. Using one trafo for each channel of course.
So in the finished amps I would have three trafos mounted, probably on top of the case with the tube front and center! I'm looking at those surplus A/B switches at allelectronics.com as cases. I bought a few and the size seems plenty for a monoblock. I'll probably paint them black and attach a piece of Paduak wood to each side to dress them up! |
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| Sherman |
Dave,
One other thing, I remember in another thread you also mentioned you would run your tube at a higher voltage (70V ?). What benefit is there to running the tube at a higher voltage in this configuration?
I thought I would stick to Joe's "plan" but if there is a big benefit from the higher voltage I might go ahead and do it. |
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| fdegrove |
Hi,
| quote: | | For the GC power trafo I was planning on using the CT as 0 volts and wiring the outside to the bridge and getting 30VDC or so after rectification. Using one trafo for each channel of course. |
That's actually the way it should be done for dual rails IMO.
Cheers,;) |
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| planet10 |
| quote: | Originally posted by Sherman
For the GC power trafo I was planning on using the CT as 0 volts and wiring the outside to the bridge and getting 30VDC or so after rectification. Using one trafo for each channel of course. |
24V CT means it is a 12-0-12 trafo... unless you stack 2 in series you are limited to 12x1.414-diode drop for the rails.
| quote: | Originally posted by Sherman
One other thing, I remember in another thread you also mentioned you would run your tube at a higher voltage (70V ?). What benefit is there to running the tube at a higher voltage in this configuration? |
Joe used 35-0-35 (ie 70 V anode to cathode) to keep the voltage in the usual SS range . I beleive these are happiest with 200-250 V total.
dave |
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| Sherman |
| quote: | Originally posted by planet10
24V CT means it is a 12-0-12 trafo... unless you stack 2 in series you are limited to 12x1.414-diode drop for the rails.
Joe used 35-0-35 (ie 70 V anode to cathode) to keep the voltage in the usual SS range . I beleive these are happiest with 200-250 V total.
dave |
The voltage between the two outside leads on the trafo is 24 volts. I can connect those leads to the bridge and use the CT as zero volts. At least that's how I did it with on of my GCs. (That one was only a single bridge but it worked.)
I looked up the specs on the tube and found there are a few different ones with slightly different specs but I did notice the higher voltage. Hmmm. I'll have to give the voltage some more thought, though I have to admit liking only having to come up with 35VDC! |
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