Redboy, thank you for sharing. That thing is a monster.
My coolest vintage tube amp!
- Thread starter Redboy
- Start date
Most likely a piece gear for telecom or mobile industrial use. This is a good example of how "point-to-point" wiring should be done. Compare that with typical consumer grade equipment of the same age.
Mike Stehr
Poverty Audio
I love the 40-50's military/industrial PTP wiring.
So what's the frequency response of that amplifier?
So what's the frequency response of that amplifier?
I've seen that kind of color mismatch between chassis/transformers and decals before. Not uncommon on military electronics of that era.
Neat, Nate
Yeah, right? Some of my favorite hifi amps like the Pilot 232 are just a rat's nest by comparison!
I don't know, exactly. I suspect it suffers a little on the frequency extremes, but not terribly.
It's in the system now!
I used it for a while when I got it about a year ago, and then pulled it out again. Just put it back in again a couple days ago.
When I first tested it, I brought it up slowly on a variac because it is bone stock, absolutely original. I'm not a proponent of running such old equipment without updating it, but I am loath to make any changes to this thing, if I can avoid it.
You can see in one of the photos above that I was able to use two existing chassis holes to mount the RCA inputs in, and wired the input directly into the second stage of the 6SN7. There'd be way too much gain with the input transformers, and their frequency response isn't all that great anyway if the labels are correct (and I assume they're about right).
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That's a beauty, what's the military model number? Does it have a metal name plate attached?
One think to keep in mind is those bathtub capacitors can and do go bad. I would make absolutely sure no DC is getting through any coupling caps to protect those beautiful transformers!
Look at this one!!!! (No affiliation...)
I think I like yours better (and no doubt it sounds better) but this one is more powerful! And it uses a seldom seen output tube with a name sure to make immature people snicker
Look at this on eBay:
http://pages.ebay.com/link/?nav=item.view&alt=web&id=172449265786
RARE Vintage U.S. Army Military Signal Corps VCA RCA? STEREO Tube Amplifier
I think I like yours better (and no doubt it sounds better) but this one is more powerful! And it uses a seldom seen output tube with a name sure to make immature people snicker
Look at this on eBay:
http://pages.ebay.com/link/?nav=item.view&alt=web&id=172449265786
RARE Vintage U.S. Army Military Signal Corps VCA RCA? STEREO Tube Amplifier
chuckworkb
Super Member
Wow, very nice, and very cool all at the same time.
Good point. I tend to give the old bathtubs a pass because they're so much more reliable than old 'lytics, but good to be reminded that they're not infallible! If I decide to run this thing long term, I'll do some more testing.
That is funny! I've been watching that one for a while, and would love to hear what it can do. As someone pointed out about my amp, most of the copper in the output transformers is dedicated to windings on the higher impedance secondary taps - they're probably not as robust as their size would suggest. Same goes for those, I'd guess.Look at this one!!!! (No affiliation...)
I think I like yours better (and no doubt it sounds better) but this one is more powerful! And it uses a seldom seen output tube with a name sure to make immature people snicker
Look at this on eBay:
http://pages.ebay.com/link/?nav=item.view&alt=web&id=172449265786
RARE Vintage U.S. Army Military Signal Corps VCA RCA? STEREO Tube Amplifier
Love it, Dennis!
MickeySmile
Well-Known Member
It is very "delicious". How does it sound compare to the 46 SE mono blocks that you built?
Binh
How does it sound compare to the 46 SE mono blocks that you built? Binh
Glad you like it! As a fellow SE aficionado, I'm sure you can see the potential in it!It is very "delicious".
Binh
There are similarities to my 46 amps. This amp is very quiet, due in large part to the excellent power supply, I am sure. Channel separation is really great, and the tone is wonderful. There's a true SE flavor to it, but it doesn't have quite the liquid clarity of a true single-ended triode.
I think the frequency extremes are a little rounded off, but not in an obnoxious way. This thing is VERY listenable, and quite enjoyable.
I was repairing an old military signal generator in the fall, very similar age and construction. The bathtubs used as coupling caps (same style as yours) were all leaky enough to totally throw off operating points, it would be fine when cold then go nuts after it was totally warmed up. I just lifted one end and wired film caps in place. (Yeah I know a bit of a hack!)
All the above chassis paper in oil cans worked as new... I think those bath tub style caps can't be lumped together with the nearly indestructible rectangular can paper in oils, despite their similar appearance.
