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Old 4th November 2008, 12:20 PM   #111
w5jag is offline w5jag  United States
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Quote:
Originally posted by vinylkid58


May I ask what those finals are. Anything with an anode cap gets my attention.

Jeff
General Electric 6DQ6B.

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Old 29th May 2009, 06:42 PM   #112
ipop07 is offline ipop07  Canada
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Maybe this comes as a dumb question for yous, and you will probably go do some reading, which I honestly did. But can this amp be used as a guitar amp? Or be modified to be used as a guitar amp?

(have some mercy my nobness, that I keep proving over and over again as I post stuff on this forum)


thank you
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Old 26th November 2010, 02:13 AM   #113
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I have done a choke input Simple SE, but I did it differently. I used two chokes... This allows the original CLC filter to remain in place and a LCLC filter to be used for choke input.
Well, I finally got around to doing this to mine. Even before I even decided to build a Simple SE, I wanted to use this beautiful pair of 1945 vintage 6L6GA. I used them as the "models" in my chassis design concepts. Unfortunately, they told me the Simple SE voltage would be too high to safely run these tubes. The choke input seemed like a good way to drop a lot of voltage without having to swap out for a different power transformer.

I found a spot to sneak in a little Triad C-24X, which ends up being the second L in the filter. The larger Hammond 159Q is the input choke. The hardest part was cutting the trace on the circuit board - for two reasons. I hated to make a more or less permanent change to the board, even if can jumper around it later to reverse the mod. The second reason was the copper on George's board is really thick, and even with a sharp X-acto I had to work a bit to get a clear cut.

With the choke input, B+ is about 335 VDC. I'm wondering if I should make any other changes, perhaps to the cathode resistors (currently 810 ohms) or possibly jumping out R14 to account for the lowered B+. I do need to make a quick measurement of the 6L6 cathode voltage, and also of the 12AT7 plate voltage. But first, I'm going to take a little time to finally enjoy these sixty-five year old tubes.

Click the image to open in full size. Click the image to open in full size.
http://i69.photobucket.com/albums/i4...E/P1150138.jpg
http://i69.photobucket.com/albums/i4...E/P1150148.jpg
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Old 26th November 2010, 02:32 AM   #114
w5jag is offline w5jag  United States
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I don't think you will need to jumper R14/24. For the 6L6GA and 335 volts, 470 ohm would be a good starting point for the cathode resistor.

With that B+ voltage, 6V6 and 6F6 will work well. An 810 ohm cathode resistor is about right for them.

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Old 28th November 2010, 01:59 AM   #115
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For the 6L6GA and 335 volts, 470 ohm would be a good starting point for the cathode resistor.

With that B+ voltage, 6V6 and 6F6 will work well. An 810 ohm cathode resistor is about right for them.
I measured the idle current for the 6L6GA, and came up with about 33.6mA average. That's only ten watts dissipated in the tube. I'll fiddle the cathode resistor and see what happens.

I popped in a pair of 6V6GT, and they sounded just fine.
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Old 28th November 2010, 03:55 AM   #116
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Originally Posted by Ty_Bower View Post
I wanted to use this beautiful pair of 1945 vintage 6L6GA.
Lovely!

Click the image to open in full size.

jeff
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Old 28th November 2010, 03:29 PM   #117
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Lovely!
Thank you. I think the lighting came out better in this photo... although I need to do a little dusting on the chassis.

Click the image to open in full size.
http://i69.photobucket.com/albums/i4...E/P1150163.jpg
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Old 28th November 2010, 06:25 PM   #118
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Sherri and I have been sorting through, and eliminating our lifetime collections of "stuff" so that we can reduce the expense of renting storage space. During the process I discovered some boxes full of tubes that I had forgotten about. One such box contained about 20 6L6GA's and 6L6GAY's. No clue how many of them are good, but one or more projects will come from them. The easiest will be a SSE with one of the HP power transformers that I have.
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Old 29th November 2010, 02:34 AM   #119
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Originally Posted by tubelab.com View Post
Sherri and I have been sorting through, and eliminating our lifetime collections of "stuff" so that we can reduce the expense of renting storage space. During the process I discovered some boxes full of tubes that I had forgotten about. One such box contained about 20 6L6GA's and 6L6GAY's. No clue how many of them are good, but one or more projects will come from them. The easiest will be a SSE with one of the HP power transformers that I have.
Hello Gents,
House cleaning and sorting memories in California too. I put my hands on my stuffed but never tested SSE, Allied 540 volt CT PT. Triad 6H choke, 70uf motor run capacitor and the best part. The best part is a repurposed chassis with a Aerojet General property sticker on it. Aerojet builds rocket engines. When I was a kid in Boy Scouts we went to visit a MIT PhD’s home DIY shop. The guy was a metallurgist and head of the Aerojet foundry where they cast rocket engine nozzles. In his home shop he built custom engineered race boat turbochargers, intake manifold, and propellers. He built them from the ground up not some GM or MoPar stuff.
I was hooked on mechanical engineering and DIY. Sorry for the digression.
DT
All just for fun!
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