| Proud Papa Syndrome (Check out my new amp...) [message #8769] |
Sun, 30 January 2005 08:42  |
TubeCraft
Messages: 30
Registered: May 2009
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Baron |
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Hi there all, I just finished my new PP 6B4 amp. It uses the ST70 transformer set on a prototype stainless chassis, with brass and stainless hardware. I doesn't mean much, when I say that it's best thing I ever heard, because I haven't heard a lot of good amps, but I have experienced (and participated in as a sound technician) a lot of live music and theatre over the years. It has an incredibly rich tone with a lot of interior subtlety. The circuit is a 6S4 cascaded into a 7044, driving a Hammond 124E IT in a parafeed config. I basically copied the topology of the WE86A. I call it the Franklin 15. This was taken before the amp was wired. Now it's a thing of beauty with all the tubes lit up at night. TC
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| Re: Proud Papa Syndrome (Check out my new amp...) [message #8773 is a reply to message #8771] |
Sun, 30 January 2005 10:50  |
TubeCraft
Messages: 30
Registered: May 2009
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Baron |
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She'll take a 5687 or a 7044 or a 6900 (should you be lucky enough to have any of those), they're similar enough to work in that spot.
It'll take most any 5v rectifier that can deliver the current. 5u4 or 5AR4 or GZ37. At the moment, the B+ is right for NOS 6B4s - when I run the Sovteks I can crank up the B+. It's also easily converted to fixed bias for up to 15wpc. It's 7wpc currently.The chassis is 10x17. The largest that would fit in my cheapo cabinet. Speakers are old Klipsch Heresys circa 1977 - still alnico magnets then - at least on the mids and tweeters. (They're slightly modified.) Driven from the 8 ohm tap. TC
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| Niiiice! [message #8778 is a reply to message #8769] |
Sun, 30 January 2005 13:19 |
PakProtector
Messages: 935
Registered: May 2009
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Illuminati (2nd Degree) |
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Hey-Hey!!!,
that is the first mention I have heard of the 6S4 in a bit. Nice looking chassis. I would try some small motor run oilers instead of the Solen caps. My experience has not been positive with the dry metalized solens( except when I have taken them out! ).I'd love to hear it.
regards,
Douglas
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| Re: Niiiice! [message #8780 is a reply to message #8778] |
Sun, 30 January 2005 14:07 |
TubeCraft
Messages: 30
Registered: May 2009
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Baron |
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Yeah, I'll be replacing the solens in various positions as time goes by and as I collect more motor-run caps and Vitamin Q's. The chassis is a bit small to go as wild in this direction as I want to. I'm not as impressed with the Cerafines as I had hoped - perhaps they need to breakin longer... I'm getting some Angela tin foil caps to try. My budget is a bit limited for the more exotic types. The world needs a good $10 1uf 600v Teflon cap. Alternately, I'm going to obtain some some input transformers and go the completely balanced route - that'll get a few caps out of the chain. I like the 6S4s - they're pretty NOS black plate Tung-Sols - NJs finest...
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| here's my 'in-progress' [message #8783 is a reply to message #8780] |
Sun, 30 January 2005 17:08 |
PakProtector
Messages: 935
Registered: May 2009
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Illuminati (2nd Degree) |
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It's my new linestage. 12B4A amplifier valve and 12BY7A active loads behind their respective 12B4. It's waiting on acquisition of the four RCA jacks and a few yards of under-hood wiring. DC filament supplies, all L-C single stages with a lot of capacitance. Still need to tune the filter voltages. I considered the 6S4 but don't need all that much gain. I am also fairly comfortable with using the 12B4.
regards,
Douglas
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| Re: she's a beauty! [message #8789 is a reply to message #8783] |
Mon, 31 January 2005 05:30 |
TubeCraft
Messages: 30
Registered: May 2009
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Baron |
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Very nice! Is it two 12BY7s per channel in the active loads? I did up a 12B4 linestage last year with a couple of Freed line transformers that I scored from Angela years ago. Ya' gotta love the 12B4 - when you can find 'em that aren't microphonic!
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