Steve, I've been using 4P1L pentode as driver for my KR300B amp for a while now, and this drives various options but often the GPA288's on Azurahorn, now the Radian 745 Be's on the Azuras. It's certainly not obtrusive ( barely noticeable) at my listening position ( ~3m ) . There is some noise from the horn when you're closer, but I couldn't say for sure it's coming from the power amp , it sounds to be more of a buzz , likely overtones of some hum pickup, this is an open breadboard at the moment . If I tap the sub-board with the 4P1L's on , I can get some microphony of course.
Definitely worth proceeding, I'd say .
BTW these are heated by Andrew's smaller DHT filament boards.
Get the teflon Loctals though - very useful . Also check out this thread on vibration isolation. I use the 'well-nuts' for the 4P1L socket mounting .
http://www.audio-talk.co.uk/phpBB2/view ... =vibration
Amplification Best Approach for Efficient Active Speakers
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IslandPink
- Amstrad Tower of Power
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#46
"Once you find out ... the Circumstances ; then you can go out"
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vinylnvalves
- Old Hand
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#47
Thanks for that Mark - How are the speakers coming along, hope the supravoxes are working as you hoped.
Will look at those dampers, i was thinking about a slightly different approach, when i have turned one the lathe i will share a picture of my idea.
Does anyone know where i can get some ptfe loctals at a reasonable price? ( I can only find then costing 5 x the price of the tube!!!)
Will have to look into Andy's heater board, and see if its going to be better than Rod's ( i expect some bias on this forum!!)
Will look at those dampers, i was thinking about a slightly different approach, when i have turned one the lathe i will share a picture of my idea.
Does anyone know where i can get some ptfe loctals at a reasonable price? ( I can only find then costing 5 x the price of the tube!!!)
Will have to look into Andy's heater board, and see if its going to be better than Rod's ( i expect some bias on this forum!!)
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IslandPink
- Amstrad Tower of Power
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#48
I'm not sure about the PTFE loctals having looked. Seem to be a couple on EBay for £10 plus postage. I got a small box of about 10 or 12 a few years ago for a good price, so I've only just got enough for myself. You might want to ask the guy at Crowthorne tubes , I think I got them from him ( poss actually from Billington ) .
I haven't ( quite ! ) got the Supravoxes installed and working, but I have one speaker in an advanced state of progress now, intending to try it out by next weekend . I've been doing everything neat as a final version this time, and it's been slow . I'm still waiting for the big chokes from Mundorf for the series crossover , they won't arrive for a couple of weeks yet .
We try not to be biased on the filament supplies ! I spent a long time working with Andrew and telling him where his fell short of the Coleman ones and one or two other options, for several months ! I can tell you the Coleman ones are very good, and absolutely rock-solid in the bass and low bass. As supplied ( may be component choices ? ) they lack some air and high treble finesse .
I haven't ( quite ! ) got the Supravoxes installed and working, but I have one speaker in an advanced state of progress now, intending to try it out by next weekend . I've been doing everything neat as a final version this time, and it's been slow . I'm still waiting for the big chokes from Mundorf for the series crossover , they won't arrive for a couple of weeks yet .
We try not to be biased on the filament supplies ! I spent a long time working with Andrew and telling him where his fell short of the Coleman ones and one or two other options, for several months ! I can tell you the Coleman ones are very good, and absolutely rock-solid in the bass and low bass. As supplied ( may be component choices ? ) they lack some air and high treble finesse .
"Once you find out ... the Circumstances ; then you can go out"
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vinylnvalves
- Old Hand
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- Joined: Sat Jan 26, 2013 12:08 pm
#49
Mark
Thanks for the advice on a source for the PTFE sockets.
Regarding the colamn filament supplies - as i am going to use this amp for HF duties (above 1000hz), the good bottom end isn't of interest, but the air and clarity in the upper octaves is. Do Andy's perform better in these octaves?
Thanks for the advice on a source for the PTFE sockets.
Regarding the colamn filament supplies - as i am going to use this amp for HF duties (above 1000hz), the good bottom end isn't of interest, but the air and clarity in the upper octaves is. Do Andy's perform better in these octaves?