2A3 "Pink SET" Amp Rebuild.

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Cressy Snr
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#1 2A3 "Pink SET" Amp Rebuild.

Post by Cressy Snr »

I've decided to do a complete internal rebuild of the pink SET.

Now I have a proper sounding project, the intention is to fix the present lash-up and make it possible to experiment with both 6AQ5 and 6V6 as driver stages for the 2A3s. I'll be using my old DIYHS ultra-low noise DC filament supplies on the output valves and will be wiring octal sockets in parallel with the existing 7-pin driver valve receptacles.

This means that it will be possible to swap driver stages between the two types, as 6V6 and 6AQ5/6005 are the same valve but in different bottles. The only difference, between them, is that 6AQ5/6005 has less max dissipation capabilities than the 6V6.

A multi-contact changeover "Owston" switch will also be fitted, so that the mains transformer can be switched between the 450V and the 375V HT taps, giving "normal" and "super" 2A3 operation for increased power when using JJ or EML types.

SS rectification will continue, as it is the most reliable option for this design.

Now then, if anyone has any old 6V6s lying around, I would be willing to buy them for a reasonable fee.

Photies as usual in due course.
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Paul Barker
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#2 Re: 2A3 "Pink SET" Amp Rebuild.

Post by Paul Barker »

Not so easy to swap as heaters different but metal can 1619 2.5v dht would be worth trying. They've always been cheap. Metal can 6v6 were also always prevalent and cheap.

By a stroke of luck AC heating the 1619 driver and the 2a3 might cancel the annoying hundred cycles you're now concerned about.

Although all these things have to be tried on breadboard first. Could try in mono.

I would ordinarily be able to supply used 6v6 and 1619 but I can't get at them. I had a mezzanine floor at the lockup collapse. The valves fell but should be alright though. Not safe to go rummage in there. Because it's winter and I set off to Hull every day for 12 to 16hiurs no time to sort lockup and money is no problem either so no need or not financially viable to sort it out (opportunity cost).

So can't help with valves but they should still be plentiful.
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#3 Re: 2A3 "Pink SET" Amp Rebuild.

Post by steve s »

I have loads of them steve... there are some metal and coke bottle types too.
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#4 Re: 2A3 "Pink SET" Amp Rebuild.

Post by jack »

What about the dirt cheap Russian ones, the 6П6С / 6P6S (from Reflektor?) - supposed to be a 6V6GT equivalent.
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Cressy Snr
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#5 Re: 2A3 "Pink SET" Amp Rebuild.

Post by Cressy Snr »

@Paul

Re 1619,
I just had a look at the thread where you used the uTracer to test extensively the 1619. Pity all the pics of the traces have disappeared because of Photobucket's revised sharing policy. Looks a good valve if used properly. Could be worth looking at on a breadboard. It would provide plenty of tinkering opportunities without messing with the pink chassis. I'm enjoying playing about with SET stuff again.
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Cressy Snr
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#6 Re: 2A3 "Pink SET" Amp Rebuild.

Post by Cressy Snr »

jack wrote: Sun Feb 04, 2018 9:04 am What about the dirt cheap Russian ones, the 6П6С / 6P6S (from Reflektor?) - supposed to be a 6V6GT equivalent.
Cheers Nick, these would make a nice little addition to the tube roller's 6V6 stash. I have a couple of JJ 6V6S, from a time when I was messing with single-ended ultralinear Osram 6P25s and KT61s.
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Cressy Snr
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#7 Re: 2A3 "Pink SET" Amp Rebuild.

Post by Cressy Snr »

steve s wrote: Sun Feb 04, 2018 8:43 am I have loads of them steve... there are some metal and coke bottle types too.
Thanks Steve,
I'll be in touch :)
I have an additional favour to ask. I've been quietly refining my semi-omni speakers, but have very kept quiet about it, given what happened on here last time I mentioned them. Paul heard them in the version just prior to the one I have now.

I reckon I have got them bang on song, so I' d be grateful for an opportunity to get a second opinion on them in your system, sometime. Perhaps we could get the "usual" listening panel together for an "honest" review?

I have a few ideas for a large pair of new omnis; ideas that could be mocked up to some extent (I'll bring a big protractor) with the smaller ones, to see if the ideas work, but it needs more than just me to be able do it properly.
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#8 Re: 2A3 "Pink SET" Amp Rebuild.

Post by jack »

Cressy Snr wrote: Sun Feb 04, 2018 9:29 am
jack wrote: Sun Feb 04, 2018 9:04 am What about the dirt cheap Russian ones, the 6П6С / 6P6S (from Reflektor?) - supposed to be a 6V6GT equivalent.
Cheers Nick, these would make a nice little addition to the tube roller's 6V6 stash. I have a couple of JJ 6V6S, from a time when I was messing with single-ended ultralinear Osram 6P25s and KT61s.
I bought 4 on spec a few years back for about USD 3 each - they're about GBP 4 each now - still a bargain if they're any good... Never got round to using mine, so I'll be really interested in what you think...

I'd send you mine, but they're about 3,500 miles away :(
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#9 Re: 2A3 "Pink SET" Amp Rebuild.

Post by Neal »

Cressy Snr wrote: Sun Feb 04, 2018 9:24 am @Paul

Re 1619,
I just had a look at the thread where you used the uTracer to test extensively the 1619. Pity all the pics of the traces have disappeared because of Photobucket's revised sharing policy. Looks a good valve if used properly. Could be worth looking at on a breadboard. It would provide plenty of tinkering opportunities without messing with the pink chassis. I'm enjoying playing about with SET stuff again.
Use Firefox Steve with the photobucket hot link fix
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#10 Re: 2A3 "Pink SET" Amp Rebuild.

Post by pre65 »

Neal wrote: Sun Feb 04, 2018 10:24 am
Use Firefox Steve with the photobucket hot link fix
I tried the Chrome Photobucket hot link fix, and it worked.

BUT, it slowed the computer down somewhat whenever I changed sites, so I ended up deleting it.
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steve s
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#11 Re: 2A3 "Pink SET" Amp Rebuild.

Post by steve s »

Steve that's great. We can sort that when your ready.. I'm sure ed and Scott will be happy to lend their ears?
And anyone else who can make a weekday session at mine.
The tube manual is quite like a telephone book. The number of it perfect. It is useful to make it possible to speak with a girl. But we can't see her beautiful face from the telephone number
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#12 Re: 2A3 "Pink SET" Amp Rebuild.

Post by simon »

Boooo! Some of us have to work during the week to pay your pensions :lol:
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#13 Re: 2A3 "Pink SET" Amp Rebuild.

Post by steve s »

simon wrote: Sun Feb 04, 2018 1:27 pm Boooo! Some of us have to work during the week to pay your pensions :lol:
Not mine Simon... but once I'm 66 that will be the case..
The tube manual is quite like a telephone book. The number of it perfect. It is useful to make it possible to speak with a girl. But we can't see her beautiful face from the telephone number
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andrew Ivimey
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#14 Re: 2A3 "Pink SET" Amp Rebuild.

Post by andrew Ivimey »

I have found that it is very definitely diffucult being a fabulously wealthy pensioner like myself. You wouldn't believe how much tax, for example, I am still required to pay, which vinyard to compliment, where to have lunch without the tedious necessity of taking the plane and so on.
Philosophers have only interpreted the world - the point, however, is to change it. No it isn't ... maybe we should leave it alone for a while.
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#15 Re: 2A3 "Pink SET" Amp Rebuild.

Post by jack »

andrew Ivimey wrote: Sun Feb 04, 2018 1:57 pm the tedious necessity of taking the plane and so on.
Just the one 'plane? Very modest of you. What about the entourage?
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