2A3 "Pink SET" Amp Rebuild.

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pre65
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Re: 2A3 "Pink SET" Amp Rebuild.

Post by pre65 » Fri Feb 16, 2018 10:23 am

andrew Ivimey wrote:
Fri Feb 16, 2018 10:19 am
Piece of piss! Phone 'em up, Simon, and tell them to warm up the capacitor making machine. 🐶🐶🐶🦐🦐🦐 just discovered emoji? what on earth do they all mean!???

Beautiful day today. I'm deep in the Chilterns, 37 miles from home...oops wrong thread, sorry. But I'm not cycling home. If I get to Stoke Mandeville I get lunch and a lift home ( in an ambulance!!!! NOT)

BEEEE YOU TEA FULL DAY.
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ed
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Re: 2A3 "Pink SET" Amp Rebuild.

Post by ed » Fri Feb 16, 2018 10:48 am

one of those emojis looks like a raw prawn....I know where your coming from!
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Re: 2A3 "Pink SET" Amp Rebuild.

Post by jack » Fri Feb 16, 2018 4:27 pm

Not deep in Chilterns, but wild camping in Oman tonight on Jebel Shams in the Northern Hajar. 8:30 pm here and just about 20C...
IMG-20180216-WA0001-960x540.jpeg

Cressy Snr
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Re: 2A3 "Pink SET" Amp Rebuild.

Post by Cressy Snr » Fri Feb 16, 2018 4:59 pm

steve s wrote:
Tue Feb 13, 2018 11:47 pm

I have a few 6v6's Steve just need to find them...
I've just acquired a nice pair of NOS, early '50s, French, grey glass, Mazda 6V6GT. They sound quite entrancing, driving the 2A3-40s. It would be interesting to compare them with some of yours.
At the moment my amp has old French valves in both the input and driver stages. I need to compare the Frenchies with Mr I's Brimars.
Now I know things are not going to self-immolate I can get down to some tube rolling in the driver section.
Happiness is not good for the economy Matt Haig.

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Re: 2A3 "Pink SET" Amp Rebuild.

Post by Cressy Snr » Fri Feb 16, 2018 5:13 pm

In more general terms, despite the problems I've had with this blasted thing, the case for three stages, with a small power valve as the DHT driver is proven to my satisfaction.

Some would say it's overkill to use a power driver unless you are driving 300Bs or big transmitter triodes, and RC coupling one is just wasting the power driver's potential to drive grids positive, but for me, it is not the power dimension, it is the consummate ease with which the SET goes about its business, when the DHT is being propelled by a power valve. All low-revving, relaxed torque and a wide power band, rather than jittery and rev-happy, if you know what I mean.
Happiness is not good for the economy Matt Haig.

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Re: 2A3 "Pink SET" Amp Rebuild.

Post by simon » Fri Feb 16, 2018 9:47 pm

Excellent result Steve.

Now bloody well leave it alone :-D

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Re: 2A3 "Pink SET" Amp Rebuild.

Post by Cressy Snr » Mon Feb 19, 2018 3:22 pm

Got sick of looking at the scratched front panel, and to respray it was just not viable, so I just screwed a couple of lengths of "D" shaped hardwood moulding to the front and gave it a couple of coats of mahogany coloured Danish oil.

It looks OK and covers a multitude of sins:
Image

I'll leave it alone now...honest.
Happiness is not good for the economy Matt Haig.

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Re: 2A3 "Pink SET" Amp Rebuild.

Post by simon » Mon Feb 19, 2018 8:46 pm

:-)

Don't touch it for at least 10 years. Doctors orders.

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IslandPink
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Re: 2A3 "Pink SET" Amp Rebuild.

Post by IslandPink » Mon Feb 19, 2018 9:12 pm

Yes, no picking at it !
White flags of winter chimneys waving truce against the moon ( Mitchell )

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Re: 2A3 "Pink SET" Amp Rebuild.

Post by Cressy Snr » Sat Mar 24, 2018 2:35 pm

I decided on a whim, to compare my pink SET to the solid state "NVA Inside" I built. It turns out that both amps are equally awesome! :D

That's what this hobby is all about, transistor nutters and valve nutters, coming together
to make equally awesome sounds.
Long may it continue! :mrgreen:
Happiness is not good for the economy Matt Haig.

Ant
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Re: 2A3 "Pink SET" Amp Rebuild.

Post by Ant » Sat Mar 24, 2018 3:18 pm

Anyone done a hybrid?

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Re: 2A3 "Pink SET" Amp Rebuild.

Post by little eddy » Sun Mar 25, 2018 1:03 pm

A hybrid approach is why I started looking at SS power amp. It might also make my OB speakers an option with me being domestically limited to 15" max baffle & 12" drivers.

I will start a new pre-amp thread once I have finished the power amp but was thinking of an 2A3 driver. The other option is single MP41 as my current KT66 amp.

Would be interested in what operating point for a 2A3 driver would be as have seen one scheme at I think just 15mA.

Interestingly was looking at the F4 which is said to be one of the most neutral SS designs and may be suited to something like the 2A3 if it can swing enough voltage.
Thorens TD-125 & 'Snail' phono/pre, NAS/SBT, CS4398 DAC, Rocky KT66 amp, still messing with OBs.

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Nick
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Re: 2A3 "Pink SET" Amp Rebuild.

Post by Nick » Sun Mar 25, 2018 1:56 pm

76 makes a good driver for a f4. Tried it some years ago.
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Re: 2A3 "Pink SET" Amp Rebuild.

Post by Cressy Snr » Wed Apr 11, 2018 11:31 pm

If you've been reading the DIY NVA solid state amp build thread, you'll have read how the KISS philosphy has led to excellent musical quality. The power rails just go end to end on the PCB, with each stage strung off the rails with no isolation between them. The stages talk to each other unhindered.

Inspired by this uncomplicated approach, I've reworked the power supply on the 2A3 SET so that there is no isolation of one stage from any of the others. I'll put up a pic of the insides of the SET tomorrow.

The results are really rather good.

More on that tomorrow.
Happiness is not good for the economy Matt Haig.

RhythMick
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Re: 2A3 "Pink SET" Amp Rebuild.

Post by RhythMick » Thu Apr 12, 2018 7:53 am

I'd be interested in the circuit diagram if you have one

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