6B4G - The Resurrection Shuffle

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Paul Barker
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#181 Re: 6B4G - The Resurrection Shuffle

Post by Paul Barker »

Anyway, I messed up in my head already, found an old project chassis and started planning allsorts of insane stuff. Then melted down crashed and burned. It may be a slow journey and the hardest part is making it simple.

there is a hammomd interstage in there. There will probably be a triode el84 driving the 6b4g by interstage. There will me something driving that, cant say what yet, maybe what Steve said if I can find a couple. my opts for this project are of a budget nature some R core which I bought when they first came out and have always performed in such an amp.
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#182 Re: 6B4G - The Resurrection Shuffle

Post by Cressy Snr »

Paul Barker wrote: Fri Sep 22, 2017 9:13 am It may be a slow journey and the hardest part is making it simple
That's the problem, isn't it. The more you know, the more you complicate.
Laser like focus and discipline are what's needed. Unfortunately I have neither. :lol:

But....let's see what can be done.
I feel a bit more purposeful now.
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andrew Ivimey
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#183 Re: 6B4G - The Resurrection Shuffle

Post by andrew Ivimey »

Hello Boys, surely the simplicity of Hammond heater transformers with the centre taps is fine and dandy with 2A3s?

What's wrong with AC ( could understand if we were talking something Russian ... and transmitter)?
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#184 Re: 6B4G - The Resurrection Shuffle

Post by Cressy Snr »

Might use my centre tapped Hammond heater transformers with the RC snubbers fitted, à la MJ's Linear Audio article, plus the customized snubber networks Nick derived for me with his magic box the other week, on the mains TX.

Simple and might be a very interesting little experiment re unwanted buzzing and the removal thereof.

I'll install the DC modules for easy comparisons.
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#185 Re: 6B4G - The Resurrection Shuffle

Post by Paul Barker »

andrew Ivimey wrote: Fri Sep 22, 2017 1:09 pm Hello Boys, surely the simplicity of Hammond heater transformers with the centre taps is fine and dandy with 2A3s?

What's wrong with AC ( could understand if we were talking something Russian ... and transmitter)?
your probably right ref the 2a3 but if we used 6a3 6b4g it would hum too much.

But I might do what you say and stick to 2a3 so as to keep it simple and see whta the 100hz hum sounds like at that voltage. Might also be a pure luck hum cancellation if used an ac heated preamp valve insteda of el84. Sometimes such luck happens. like the firts time people came here to listen to the 212 when I had ac heating withput hum because of cancellation which just happened.
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#186 Re: 6B4G - The Resurrection Shuffle

Post by ed »

Cressy Snr wrote: Fri Sep 22, 2017 2:13 pm
Simple and might be a very interesting little experiment re unwanted buzzing and the removal thereof.

I'll install the DC modules for easy comparisons.
at this stage I'm willing to place a bet.
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#187 Re: 6B4G - The Resurrection Shuffle

Post by izzy wizzy »

The journey of this thread reminds me of a similar journey of mine. I had a phono stage that had grown to incorporate everything I thought I knew. Seperate heater windings, rectification, regulators for each stage. Seperate HT windings for each channel with channel regualtion foloowed by regulation for each stage. Each cap was bypassed with smaller values throughout the whole thing including all power supply capacitors.

But there was something it wasn't doing. It just didn't engage as it should. It was more an intellectual listen.

So one day, I started removing things. All the bypasses went and I started to relax a bit more. Then the regulators and bit by bit I removed so much stuff that in the end, all that was left was a simple power supply and the audio circuit. It was a revelation.

At that point, I only introduced or changed something that kept me feeling the music and the idea that people were playing music. If I had to think about what I was comparing, it didn't go in. Bigger bass, more treble and so on just didn't cut it if I lost the flow.

Sometimes I think in this game we can convince ourselves that more control of the circuit is the way forward but maybe it isn't if things aren't free to express themselves.

cheers,

Stephen
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#188 Re: 6B4G - The Resurrection Shuffle

Post by simon »

I use AC to heat my 2A3s - just plain old Hammond filament trafos. And then I make a centre tap for the cathode resistor with two small resistors, 22R or something similar. Nice and simple, no hum pot required.

I have the kit for DC regs one day. One day. I think it may well sound better, but by how much?
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#189 Re: 6B4G - The Resurrection Shuffle

Post by simon »

Paul Barker wrote: Thu Sep 21, 2017 7:49 am shutup now ore youll have me building gm70.
You know you want to Paul :-).

100H anode choke on the 12GN7, Mundorf silver in oil coupling cap, AE amorphous 5k OPTs with 550V B+. Separate PS for 12GN7 and GM70, both LCLC, the second LC has one for each channel so 6 chokes in total. Coleman regs for the GM70 filaments. Simple as that. Just make sure they're coppers ;-).
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#190 Re: 6B4G - The Resurrection Shuffle

Post by pre65 »

I use a cascaded CCS and a grid choke on the 12GN7 anode for the GK-71 amps.

The cascaded CCS is almost as good as a separate PSU for the driver, so I'm told.

I have seen it in print somewhere that a trioded GK-71 sounds better than a normal GM70, but I can't remember where.
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#191 Re: 6B4G - The Resurrection Shuffle

Post by Paul Barker »

Some other time, this is as much about supporting Steve Emotionally in a journey I too struggle with these days.
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#192 Re: 6B4G - The Resurrection Shuffle

Post by Cressy Snr »

izzy wizzy wrote: Fri Sep 22, 2017 7:02 pm The journey of this thread reminds me of a similar journey of mine. I had a phono stage that had grown to incorporate everything I thought I knew. Seperate heater windings, rectification, regulators for each stage. Seperate HT windings for each channel with channel regualtion foloowed by regulation for each stage. Each cap was bypassed with smaller values throughout the whole thing including all power supply capacitors.

But there was something it wasn't doing. It just didn't engage as it should. It was more an intellectual listen.

So one day, I started removing things. All the bypasses went and I started to relax a bit more. Then the regulators and bit by bit I removed so much stuff that in the end, all that was left was a simple power supply and the audio circuit. It was a revelation.

At that point, I only introduced or changed something that kept me feeling the music and the idea that people were playing music. If I had to think about what I was comparing, it didn't go in. Bigger bass, more treble and so on just didn't cut it if I lost the flow.
Sometimes I think in this game we can convince ourselves that more control of the circuit is the way forward but maybe it isn't if things aren't free to express themselves.

cheers,

Stephen
Sounds encouraging.
Hopefully, with this KISS project I'll get back what I've lost :)
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#193 Re: 6B4G - The Resurrection Shuffle

Post by jack »

jack wrote: Thu Sep 14, 2017 12:23 pm
simon wrote: Tue Aug 22, 2017 8:14 pm Merlin Blencoe's power supply book is out of print now (seen Jack is looking for a copy on DIYAudio) but Merlin once posted it was because there were so many errors in it he wasn't happy with it. I'm sure most of it is just fine, but that comment alone has made me a little uneasy about its content. That said there's little new in the valve world so there should be corroborating text elsewhere.
I just found this on his website:
http://www.valvewizard.co.uk/ wrote:15 November 2013: I've been getting a lot of mail about my power supplies book. I'm sorry to say I permanently removed it from print. It contained too many mistakes and typos, and it didn't match the style of my preamp books. Do not email me asking if I have spare copies or PDFs; your email will be ignored. Fortunately, all the best material from the power supply book can now be found in the final chapter of my hi-fi preamps book!
(my highlighting)
Talking to myself again. Sad.

I now have a copy of the latest edition of Blencowe's "Designing High-Fidelity Tube Preamps" book.

There is nothing in it about valve shunt regulators.

Bah!
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#194 Re: 6B4G - The Resurrection Shuffle

Post by Paul Barker »

oh well. Thanks for letting us know though.
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#195 Re: 6B4G - The Resurrection Shuffle

Post by Cressy Snr »

Speaking of this amp,
I finished drawing up the audio circuit this morning.
It is a three stage design with a triode connected 6AU6 as the input stage.
Driver stage is a triode connected 6005W the mil spec equivalent of the 6AQ5, which is in turn, for all intents and purposes, a 6V6 in a 7 pin bottle.

The output stage is specifically designed for the JJ, 2A3-40W valve and has an anode dissipation of 27W, meaning that it is not suitable for NOS or standard, modern production 2A3s; it'd fry the poor beggars within seconds of powering up.

The chassis is to be '50s style, pastel blue with mahogany side panels.
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