Greetings Lads:
I've been away from the forum since late last year. I've had a lot on the plate these last 8 months or so and haven't sniffed solder smoke for some time.
My Hybrid A is in limbo for the moment.
In the meantime I've picked up a Hammond organ power amp. I think it may be an L100 but I dunno for sure. Pair of 6BQ5s with 12AX7 PI and a 12AX7 in the pre position.
http://cgi.ebay.com/ws/eBayISAPI.dll?Vi ... %26fvi%3D1
It most likely will become something like a Matchless Spitfire (see schematic heaven). I am not however impressed with the master volume arrangement, though I must admit I've never played one.
I've searched the archives and cannot find the alternate master volume design posted a million years ago by the Normster. In any case, I need a simple little lead amp that will probably be mic'ed in the Worship band. I'm likely to push either a red white and blues or a pair of swamp something or other 10" speakers.
I've heard the Goodsell super 17 and like what's going on there, but have not seen a scheme. I suspect he's stayed pretty close to the Matchless schematic.
Any Ideas folks? And I see not much has changed around here except the old timers post less and there are a million new names. Hi All!
Dan Hall
South Frisco on a Boat.
Master Volume discussion
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skyboltone
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Master Volume discussion
The Last of the World's Great Human Beings
Seek immediate medical attention if you suddenly go either deaf or blind.
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Seek immediate medical attention if you suddenly go either deaf or blind.
If you put the Federal Government in charge of the Sahara Desert, in five years time there would be a shortage of sand.
Re: Master Volume discussion
Hi .
There's a hugh thread over on Metro amps on PPIMV. They're having great success with making those 2 220k "bias splitting" resistors on the o/p tubes into a dual ganged 250K pot. and taking the wiper to the o/p tubes. MIND YOU..they were'nt talking cathode biased but I think it would still work.
http://forum.metroamp.com/viewtopic.php?t=4390
The meat starts a few pages in.
Stew
There's a hugh thread over on Metro amps on PPIMV. They're having great success with making those 2 220k "bias splitting" resistors on the o/p tubes into a dual ganged 250K pot. and taking the wiper to the o/p tubes. MIND YOU..they were'nt talking cathode biased but I think it would still work.
http://forum.metroamp.com/viewtopic.php?t=4390
The meat starts a few pages in.
Stew
Last edited by stoo on Sun Jun 10, 2007 3:57 pm, edited 1 time in total.
Re: Master Volume discussion
from brown note
Post Phase Inverter Master Volume
"Drawn by Mark Huss, this master volume works well with the 18watt lite to acheive cleaner tones a higher volumes and more grit at lower volumes."
it's now in my 18 lite with 120pf caps across wipers & PI lugs.
i like the fact RC time constant raise when you lower the volume so you don't hear the bass getting lower with the volume (physiological effect?), the effect could be increased with 1M pot/270K resistor in a 220K amp.
IMHO i find it slightly better than the cross master in the 18w, but both master volumes make me realize that the goodie of 18w is in power tubes distortion...if your amp has two preamp stage and a cathode follower before PI, master volume may be a good option.
mine is dimed 98% of the time
Post Phase Inverter Master Volume
"Drawn by Mark Huss, this master volume works well with the 18watt lite to acheive cleaner tones a higher volumes and more grit at lower volumes."
it's now in my 18 lite with 120pf caps across wipers & PI lugs.
i like the fact RC time constant raise when you lower the volume so you don't hear the bass getting lower with the volume (physiological effect?), the effect could be increased with 1M pot/270K resistor in a 220K amp.
IMHO i find it slightly better than the cross master in the 18w, but both master volumes make me realize that the goodie of 18w is in power tubes distortion...if your amp has two preamp stage and a cathode follower before PI, master volume may be a good option.
mine is dimed 98% of the time
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Re: Master Volume discussion
if you prefer prePI masters there's a simple one where a 1M pot takes place of the 1M PI first grid resistor with wiper going to the first triode grid
(V3 pin2 in the upper schematic).
never tried though.
(V3 pin2 in the upper schematic).
never tried though.