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Old 17th January 2007, 04:20 AM   #61
Salas is online now Salas  Greece
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EL34 sounds fatter than life to your ears as to mine, if I understood right?
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Old 17th January 2007, 04:20 AM   #62
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Quote:
Originally posted by Wavebourn


Quad of 6P3S-E gave me 80W with 375V plate/310V second grid, 4K CT transformer, 40 MA per tube bias. Some sellers claim they are 6L6-GC, but I am afraid to load them harder. However, if Tubelab tortured them and found as good as GC...
That sounds good, but the higher primary impedance of my OPT leads me to suspect that I wouldn't get quite as steep a loadline, or quite as much wattage from the tube. From the looks of things, you're pushing it anyway... which is fine but I don't like the idea of constantly rolling tubes. I'll wait for those giant-killers I mailed you to ask about

I'd rather use bigger tubes and run them a little lighter, with plenty of power, than push a smaller 6L6GC/6P3S to its limits...
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Old 17th January 2007, 05:21 AM   #63
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Quote:
Originally posted by sorenj07


That sounds good, but the higher primary impedance of my OPT leads me to suspect that I wouldn't get quite as steep a loadline, or quite as much wattage from the tube. From the looks of things, you're pushing it anyway... which is fine but I don't like the idea of constantly rolling tubes. I'll wait for those giant-killers I mailed you to ask about

I'd rather use bigger tubes and run them a little lighter, with plenty of power, than push a smaller 6L6GC/6P3S to its limits...
Yes, with 6K transformers I would go with tubes that like bigger plate voltages.

They are not giant killers, they are approximately the same size, but designed differently and use different matherials.
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Old 17th January 2007, 07:06 PM   #64
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Quote:
Originally posted by salas
EL34 sounds fatter than life to your ears as to mine, if I understood right?
I prefer ray pentodes, though EL34 sounds interesting as well.
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Old 22nd January 2007, 06:52 PM   #65
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Though the 6L6 (and variants, i.e GC, etc.) are popular, I haven't seen too many simple designs for hi-fi. This guy (Tim Williams) has quite a few schematics, (and he posted quite a few on his site, but he says don't try them, as they are just from his notes and some are unproven). But I do look to newer audiophile stuff rather than real old classic stuff that hasn't had attention in the past 40 years.
Here's one that seems to do 25 watts or better per channel, looking at the spec of the output trafo, may make a nice monoblock:

Click the image to open in full size.

So I can't say if this will work or has major flaws. Looks, too, like he winds all his iron by hand.
Looks like maybe a standard 325-0-325 power suuply will work, a decent choke, and maybe a Hammond 1645 or better for output.

His exact quotes on his schematics:
" Some of these work well. Others don't. Some may work well but were never built (..yet..). Others were never intended to work, and some are very basic or incomplete diagrams that may spit a few sparks if tried! I don't recommend you try these unless you know what you're doing. "

So if this is of interest to anyone, would like to hear any analysis on design flaws , etc., as this may be another good simpe project if it works ok.
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Old 11th February 2007, 11:47 PM   #66
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I will very soon be in a position to buy my output tubes. Is it worth it to get 6550's/KT88's instead of 6L6GC's with the Williamson circuit and 60W 6600 a-a OPT? My PSU can put out oodles of current, maybe up to 70mA per tube, at 450V... I wouldn't mind 60W of UL power...
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Old 4th August 2013, 06:13 AM   #67
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Quote:
Originally Posted by frank754 View Post
Though the 6L6 (and variants, i.e GC, etc.) are popular, I haven't seen too many simple designs for hi-fi. This guy (Tim Williams) has quite a few schematics, (and he posted quite a few on his site, but he says don't try them, as they are just from his notes and some are unproven). But I do look to newer audiophile stuff rather than real old classic stuff that hasn't had attention in the past 40 years.
Here's one that seems to do 25 watts or better per channel, looking at the spec of the output trafo, may make a nice monoblock:

Click the image to open in full size.

So I can't say if this will work or has major flaws. Looks, too, like he winds all his iron by hand.
Looks like maybe a standard 325-0-325 power suuply will work, a decent choke, and maybe a Hammond 1645 or better for output.

His exact quotes on his schematics:
" Some of these work well. Others don't. Some may work well but were never built (..yet..). Others were never intended to work, and some are very basic or incomplete diagrams that may spit a few sparks if tried! I don't recommend you try these unless you know what you're doing. "

So if this is of interest to anyone, would like to hear any analysis on design flaws , etc., as this may be another good simpe project if it works ok.
that transformer will go for an impedance of 4.2k A-A at 8ohm load, and some fast calculations in the computer shows me that the inductance in the primary will go over 100 Hy and with few losses, and will go very good for a buget opt

Last edited by maton00; 4th August 2013 at 06:15 AM.
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Old 4th August 2013, 09:49 PM   #68
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Originally Posted by maton00 View Post
that transformer will go for an impedance of 4.2k A-A at 8ohm load, and some fast calculations in the computer shows me that the inductance in the primary will go over 100 Hy and with few losses, and will go very good for a buget opt
Keep the OPT, but not the rest. It has major flaws:

*) No NFB: Open loop, 6L6s sound nasty. They make lots of higher order harmonics that is very hard to listen to for very long. The 6L6-oids definitely need the help to sound good. That means local as well as gNFB.

If you're using 6BQ7s for your LTP, it's better to get the Vpk higher. SS active tail loading would require much less voltage, and operate the 6BQ7s higher up on the plate characteristic. Better still would be to cascode the 6BQ7s for the LTP. Since it's using an LTP, there is already a convenient gNFB summing node available there.
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Old 4th August 2013, 10:47 PM   #69
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that opt will go better with 6p3s and 6n1p wavebourn´s site amp?
what do you think of that design?
I think it may be a good overkill to get 10 to 15watts with a pair of the 6P3S-E
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Old 5th August 2013, 01:33 AM   #70
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Originally Posted by maton00 View Post
that opt will go better with 6p3s and 6n1p wavebourn´s site amp?
what do you think of that design?
I think it may be a good overkill to get 10 to 15watts with a pair of the 6P3S-E
Looks pretty good.

Quote:
that transformer will go for an impedance of 4.2k A-A at 8ohm load, and some fast calculations in the computer shows me that the inductance in the primary will go over 100 Hy and with few losses, and will go very good for a buget opt
If the OP is right, that 4K2 (P-2-P) would go nicely with a pair of 6AV5s or 6BQ6GTAs for a solid 30W of output. The DC rail is a bit on the low side, so you could get it up to 350Vdc, or accept a bit less power running at 300Vdc.

These TV HD finals also make for some excellent audio finals. They'll do 30W+ easily, and could go even higher with screen drive.
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