NEW  Matt presents bias and operation data for the 6V6 tube in SE operation - 6V6 Single-Ended (SE) Ultra Linear (UL) Bias Optimization.

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 Post subject: Re: Smallest possible ampPosted: 30 Aug 2019, 15:07

Joined: 02 Mar 2009, 12:41
Posts: 1110
Location: Vänersborg, Sweden
Came to think of it, got a 12B4A-Darling I was struggling with ...

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Magnus

“If you don't know where you are going, any road will get you there.”
―Lewis Carroll

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 Post subject: Re: Smallest possible ampPosted: 30 Aug 2019, 17:11

Joined: 23 Feb 2017, 02:02
Posts: 618
Very nice, I like

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 Post subject: Re: Smallest possible ampPosted: 31 Aug 2019, 02:58

Joined: 02 Mar 2009, 12:41
Posts: 1110
Location: Vänersborg, Sweden
The box on the last pic is a military dosimeter box and amplifier is the basic Darling but with 12B4A. Never got this one to sing and never had the energy to find the fault. Maybe just take it apart and start from the beginning.

Made som basic calculations: a standard 6AQ5-amp (SE) will draw at most 100mA at 290V. Pure and simple arithmetics tells me that at 12V, the power source must be good for at least 2.4A. My 18Ah battery will (theoretically) last 7,5 hours.

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Magnus

“If you don't know where you are going, any road will get you there.”
―Lewis Carroll

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 Post subject: Re: Smallest possible ampPosted: 31 Aug 2019, 04:12

Joined: 13 Jan 2018, 21:33
Posts: 274
Location: australia
Nice images from Vänersborg in wintertime. Looks like a pretty place.

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John

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 Post subject: Re: Smallest possible ampPosted: 31 Aug 2019, 05:32

Joined: 01 Jun 2013, 09:05
Posts: 907
Just looking at this,

Very interesting thank's Magnus

Regards
M. Gregg

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 Post subject: Re: Smallest possible ampPosted: 31 Aug 2019, 06:43

Joined: 02 Mar 2009, 12:41
Posts: 1110
Location: Vänersborg, Sweden
This guy made great efforts to have everything documented. Most of us use a DVM to check voltages and then lend an ear to see that the circuits are working "normally".

Woodo: I started using my LOMO Kompakt Avtomat, bought in USSR 1989 and then bought a Soviet Leica, the FED-2 last Autumn and then it just went on ... Shooting with real cameras and real (reel) film is much more fun and challenging than using a digital camera.

I still wonder what design to use. I got my three amps stored away, but I also have an STC (Super Triode Connection) using an ECL82/6BM8 and an odd 6EJ7 as CCS. A nice and different design.

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Magnus

“If you don't know where you are going, any road will get you there.”
―Lewis Carroll

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 Post subject: Re: Smallest possible ampPosted: 31 Aug 2019, 14:01
 Project Author

Joined: 04 Jun 2008, 20:59
Posts: 4098
Location: Arizona, USA
Hi, An ancient thread...but interesting. Yes you can use nuvistors as a phone amp. They are relatively low voltage but can handle (some of them anyway) up to about 25 ma. I can envision a pentode one as a voltage amp feeding a triode output SE. Or even with a splitter feeding a push-pull pair. A few hundred milliwatts ought to be possible. Also the SE amp I cooked up with 6GV8s is actually pretty nice and good for a clean 1 watt. I attached a copy of an early version of the schematic. A later version is the basis for the Oddwatt Alpha.

Good listening
Bruce
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 Post subject: Re: Smallest possible ampPosted: 31 Aug 2019, 14:22

Joined: 02 Mar 2009, 12:41
Posts: 1110
Location: Vänersborg, Sweden
I've got a bunch of 6GV8, or 6F5P as Russians call them. Have to find a) the half-built amps I have ben referring tomy collection of tubes tomorrow. According to the weather forecast it's gonna rain.

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Magnus

“If you don't know where you are going, any road will get you there.”
―Lewis Carroll

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 Post subject: Re: Smallest possible ampPosted: 01 Sep 2019, 21:15

Joined: 13 Jan 2018, 21:33
Posts: 274
Location: australia
My first SLR was a then East German made Practika. I fondly remember having to use the sunny f16 rule to confirm what the exposure meter was telling me which was fun. Sometimes got a good exposure. Not the camera's fault but the operator's. Still have some b & w photo from that camera developed at an adult education course. How new technology changes things.

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John

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 Post subject: Re: Smallest possible ampPosted: 02 Sep 2019, 02:41

Joined: 23 Feb 2017, 02:02
Posts: 618
I'm more into push pull since the sound luster which is SE and modded to limits are not yeilding satisfatory sound quality.

Which was my relaxing and for fun project.
After university exams last year so tired and and not in the mood to do 3-14 days of R&D before I get any working model and get to listen to it.
Relaxing and for fun means things are done in half to a day and you get to listen to the mods on the same day........ Sometimes two, three days but fast results to relif pressure.

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