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6AQ5 to "Mini-6V6" converter


 :
10/26/1997 9:40 AM
R.G.
6AQ5 to "Mini-6V6" converter
I was replying to an email question about the place in the RCA manual where it says about the 6AQ5 that "within the limitations of its ratings, the 6AQ5 is equivalent to the larger 6V6" when it struck me that it would be possible to use an octal base and a 7 pin mini socket to make an adapter to plug a 6AQ5 into a 6V6 socket.  
 
That would work as long as the plate voltage could be decreased to cut the plate dissipation down to where the 6AQ5 would survive. The 6V6 is rated at 14W plate dissipation, the 6AQ5 at 12W. Fender ran the 6V6 at up to 20W, and probably got away with it since the 6V6 is physically large for such a low plate dissipation. You probably couldn't put an AQ5 through such abuse - hence the lower B+ need.  
 
I -think- that you could also put a power zener in the adapter that would wipe off some excess plate voltage and let you keep any modifications out of the base amplifier. That would make for about 6-8W output power, and --cheap-- output tubes, and creamy distortion at lower powers. I must have 100 6AQ5's that I have collected in bagging other tube types. I have an affinity for the sound of a single-ended 6AQ5 in my homemade practice amp.  
 
I don't have it fully worked out, just speculating. Anybody willing to do some craftsman work to try this out? A Princeton or Deluxe would be a good place to start.
 
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10/26/1997 12:39 PM
ROBERT HINSON

HEY RG, I BUILT AN AMP USING 6 6005W'S WITH 2 5V4G RECT. TUBES FOR THE POWER SUPPLY. I BELIEVE I RAN THEM AT AROUND 380V AND 20MA ON THE PLATES WITH THE STANDARD TWEED BASSMAN/MARSHALL PREAMP DRIVING 'EM. IT SOUNDED PRETY COOL AND PRETTY DAMN LOUD. THE 6005W'S APPEAR TO BE A VERY WELL MADE TUBE--THE BATCH I GOT WAS VERY SOLID WITH THE INNARDS ATTACHED LIKE A TANK, NO RATTLING. ANYWAY I JUST THOUHGT I'D THROW THAT INTO THE MIX.
 
10/27/1997 12:37 PM
R.G.
Yeah, the 6AQ5/6HG5/6005 is an excellent tube, just small. It was designed for the output stage of mobile equipment, I think, so it has vibration resistance in it's ancestry.
 
10/27/1997 5:42 PM
Cosmik Debris

I have thought about doing something similar. I would like to put some EL84 in my 6L6 output stage and bias them to Class A. There are some converters called Black Jack converters and also THD Yellow Jackets (same circuit) which do this. They plug straight into the octal base and drop the plate voltage to 320V and cathode bias the EL84.  
 
I was thinking about using a power zener. Would you also need one for the screen voltage? I guess 5-10 watt zeners would be somewhere in the right ball-park.
 
11/4/1997 8:00 AM
Y.

Let me now what you find out. I have recently bought an old PiloTone tube Hi-Fi amp that is almost indentical to the Tweed Deluxe circuit (plus an extra 12A?7 socket for...something. Maybe reverb?). I am planning on making this my first amp project (after I get a lot of other stuff off my workbench). It might be cool to have a few extra options on tubes and sound.  
 
-Y.  
(wyatt poist)
 

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