All 7 pin tube amp—Video DemoClips Added 1/27/18

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didit
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Re: All 7 pin tube amp

Post by didit »

brewdude wrote: Thu Sep 07, 2017 11:51 pm Changing the screen voltage has a pretty noticeable effect. At higher voltages it seems to be more glassy and lively and lower voltages more velvety and compressed.

If I were to make the two pentode stages dissimilar, which way do you think would be more desirable?
Seems you somewhat answered your own question, but now should decide what tone qualities you are ultimately after. Second in chain has more distortion potential with gain from the first to drive.

Best .. Ian
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Re: All 7 pin tube amp

Post by brewdude »

Thanks didit,
I'm curious, in your experience, would you consider it more beneficial to have the more compressed fuzzy stage first and then the glassy dynamic stage or vice versa?
gtomax
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Re: All 7 pin tube amp

Post by gtomax »

brewdude wrote: Fri Sep 08, 2017 5:20 pm Thanks gtomax,

Wow, that is a crazy circuit. Thanks for posting.
Is that inductor part of a tone circuit?
Looks like a cathodyne PI followed by a gain stage?

I like the cooler weather this week too.
Yep - Lover used it to cancel the hum of a single coil input. My understanding is that the inductor was wired in reverse to swap polarity of the signal and cancel the AC hum from the guitar input just like the 2nd coil in a humbucker (which he also designed) did. Pretty ingenius, just move the 2nd coil into the amp rather than in the guitar.
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Re: All 7 pin tube amp

Post by brewdude »

gtomax wrote: Sun Sep 10, 2017 4:09 pm
brewdude wrote: Fri Sep 08, 2017 5:20 pm Thanks gtomax,

Wow, that is a crazy circuit. Thanks for posting.
Is that inductor part of a tone circuit?
Looks like a cathodyne PI followed by a gain stage?

I like the cooler weather this week too.
Yep - Lover used it to cancel the hum of a single coil input. My understanding is that the inductor was wired in reverse to swap polarity of the signal and cancel the AC hum from the guitar input just like the 2nd coil in a humbucker (which he also designed) did. Pretty ingenius, just move the 2nd coil into the amp rather than in the guitar.
Fascinating. I'm having trouble seeing how it functions as you described by looking at the schematic, but I am no electronic genius--in fact I would describe myself as knowing enough to be dangerous.
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didit
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Re: All 7 pin tube amp

Post by didit »

brewdude wrote: Sun Sep 10, 2017 3:15 pm I'm curious, in your experience, would you consider it more beneficial to have the more compressed fuzzy stage first and then the glassy dynamic stage or vice versa?
Apologies for misleading .. no real experience yet cascading small-signal pentodes. Just a single 6SJ7 amp build http://ampgarage.com/forum/viewtopic.php?f=6&t=30164, plus some breadboard experimentation. Used values as written in Gibson's original schematic. Will change it to lower screen voltage when next inside it.

Simply noting that given stage-one gain to drive it there would more range of impact tweaking with the second stage. Inclined to suggest switchable screen, add resistor in parallel adjusting voltage as desired. Needs a bit experimentation. Simpler than another elaborate VVR as you did in the past. Ultimately what works is matter of tonic taste--no?

Best .. Ian
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Re: All 7 pin tube amp

Post by brewdude »

Thanks for responding further.

I seem to like the higher screen voltage on the other amp that has the VVR on the screens which has the pentode as V2. This leads me to wish to start with the lower screen at V1 and higher screen at V2. However, I going to leave as is for a while (at least until harvest is over and all the wine is dry, malo-lactic complete, and safely into barrel... somewhere between Halloween and Thanksgiving.
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Re: All 7 pin tube amp

Post by JazzGuitarGimp »

brewdude wrote: Sun Sep 10, 2017 7:23 pm and all the wine is dry, malo-lactic complete, and safely into barrel
Oh yeah.... talk dirty to me.... :-) The wife and I are wannabe wine aficionados. We've been all over Napa and Sonoma tasting, talking, learning - We've even taken a few winery tours... About 4 years ago, we made a batch of Old Vine Zinfandel from a kit. It was a fun experience, but didn't turn out as well as I would have liked; the wine has a strange note in the nose and in the mouth. Though if I decant a bottle and let it stand for a handful of hours, the funky aroma and taste dissipate and it's almost drinkable....almost.... LOL
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Kagliostro
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Re: All 7 pin tube amp

Post by Kagliostro »

Many thanks for the link didit

K
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Re: All 7 pin tube amp

Post by brewdude »

JazzGuitarGimp, I live in Napa (born at the St. Helena Hospital), and work in Oakville at a medium size family owned premium winery (we do no more than 80,000 cases a year). We have only 4 labels (Cab, Reserve Cab, Chard, and Sauv Blanc). The wine is quite delicious and fairly expensive. It's a good gig--this is my 15th harvest--only 11 more years to got the Rolex (might not make it).
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JazzGuitarGimp
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Re: All 7 pin tube amp

Post by JazzGuitarGimp »

brewdude wrote: Sun Sep 10, 2017 8:49 pm JazzGuitarGimp, I live in Napa (born at the St. Helena Hospital), and work in Oakville at a medium size family owned premium winery (we do no more than 80,000 cases a year). We have only 4 labels (Cab, Reserve Cab, Chard, and Sauv Blanc). The wine is quite delicious and fairly expensive. It's a good gig--this is my 15th harvest--only 11 more years to got the Rolex (might not make it).
One of our favorite wineries (Turnbull) is in Oakville. Their cabs are out of this world yummy!
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brewdude
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Re: All 7 pin tube amp

Post by brewdude »

Solid choice.
I am not too far from them.
We are the pinkish colored mission style building (complete with bell tower) on the Oakville Crossroad. The owner is the former CFO of Atari. In the early days (before I worked here) the lobby downstairs was packed with old video game consoles.
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TUBEDUDE
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Re: All 7 pin tube amp

Post by TUBEDUDE »

Brewdude, if by chance you work at Far Niente, i am a big fan of your work. Well, i guess several of the Oakville wineries are faves also.
Tube junkie that aspires to become a tri-state bidirectional buss driver.
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Re: All 7 pin tube amp

Post by brewdude »

No, but they are another great choice.

I work at Groth Vineyards and Winery. Groth originally gained notoriety as the first winery to score 100 points on their Cabernet back in the late 1980's. Our style of winemaking has evolved much over the last few decades, and I think the new Winemaker, Cameron Perry, is taking the styles we produce to a new higher level of quality. I'm quite proud of the wines we produce.
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Re: All 7 pin tube amp

Post by brewdude »

So, I did a little experiment today... I jumpered the wiper of the gain pot to the wiper of the tone pot, effectively eliminating the tone pot and achieved a significant increase in gain... and I liked it--a whole lot!

I going to need a tone defeat switch--maybe a push/pull pot(?). Then again, maybe I should consider eliminating the tilt tone control altogether, possibly replace it with a simple tweed style tone circuit.
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Re: All 7 pin tube amp

Post by Mark »

Nice build and a good idea.
Yours Sincerely

Mark Abbott
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