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Old 16th February 2009, 02:24 AM   #1
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Default Tried this out, but needs more gain. . .

Voltages listed aren't real accurate. Used an old analog meter that shows considerable variation from range to range.

http://img514.imageshack.us/img514/1...al169aavl5.png

Figured I'd give it a try , it was easy enough.
I've asked about a similar design before, and basically was told it wouldn't work. It does work , and sounds very good, TONS of midrange resolution , but it just doesn't play loud enough . Perhaps if I had some speakers that were 10db more efficient, but alas , I don't.

This is S O simple. There is really very little to this design. Any thoughts how I can increase the output without increasing the amount of tubes ?I run a passive volume control from the DVD player, no preamp. I've thought of increasing output from my DVD player , but haven't looked into it yet.

Any thoughts ? Besides that I'm a nut ?


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Old 16th February 2009, 02:35 AM   #2
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You've built one of these: http://www.triodeel.com/compact.html

But you left out the first AF gain stage. You need to add another tube. Maybe using a transformer instead to get the voltage up might work? I dunno. You're not going to get the output you want with only a 1 volt input swing. You'll need more like 20 volts to fully drive those 6V6.

I wonder what would happen if you rewired the sockets for something like a 6SN7 and adjusted the cathode resistance and output transformer load appropriately?
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Old 16th February 2009, 02:51 AM   #3
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I've looked at that schematic a time or two .

I was just looking on the Triode Electronics website. Seems as though if I were to run these Pentode I would get considerabley more output from them.

From what I've read, it seems that Pentodes typically need about 1/3rd as much drive as compared to the same tube run Triode to achieve the same power output. In other words, much less input = equivalent output , or same input = considerabley more output. I'm gonna go switch them over to Pentode. I'll let ya know what happens. . . .




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Old 16th February 2009, 03:21 AM   #4
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Try this:

Only 2 more tubes 6CG7 or 6SN7 I even used 8FQ7 for some time with no ill effects from lower Fil. voltage
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Old 16th February 2009, 03:34 AM   #5
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Here's one you can do with 1 extra tube (12AX7)
PP 6V6 amp
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Old 16th February 2009, 03:38 AM   #6
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Quote:
Originally posted by DigitalJunkie
Here's one you can do with 1 extra tube (12AX7)
PP 6V6 amp

Basically the same as my suggestion. I meant 1 tube / channel
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Old 16th February 2009, 03:54 AM   #7
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You have two octal sockets, try a pair of 6EM7's.

If you wanted to keep the current setup, maybe a 1k:10k step-up transformer would help you out.
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Old 16th February 2009, 04:44 AM   #8
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Audiowize, did you mean the 6EM7's instead of the 6V6's ? Meaning in a single gain stage ?

I hooked them up like this now :

http://img101.imageshack.us/img101/2...apentodcn9.png


Plays louder , still not loud enough. I don't seem to like Pentodes as much as Triode tied pentodes. They just don't seem to do it for me. This setup sounds good, but not as good as the first one I tried.

Just so you guys know where I'm coming from, my main setup is currently this :

http://img101.imageshack.us/img101/5...9aarevizj4.png

http://img101.imageshack.us/img101/7...pplyforfn4.png

I think I need to lose the triode tied 6an8. I have some new matched Sovtek 6SL7's and some sockets to go with. Should I go for them, or not a good match for triode tied 6V6's ? I'm actually running 6p6s, or a Russian 6V6 style Tetrode.

Anyway, what are the thoughts on the 6SL7 ?




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Old 16th February 2009, 05:10 AM   #9
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OK, so I looked up the 6EM7's. I see they are a dual stage tube , meaning a driver and output triode in one glass tube. That answers that question.

Digital Junkie, I see you've posted a Magnavox schematic. Perhaps you noticed my amp started life as such ?

I'm gonna look into a 1:10 step up transformer. Thanks guys.




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Old 16th February 2009, 06:59 AM   #10
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It's actually the amp from an old Sears Silvertone console,pretty similar to the Magnavox schematics and amps I've seen pics of.
Maybe the Silvertone amp was made by Magnavox? I dunno.
It's a pretty simple amp,and sounds darn good.
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