6B4G - The Resurrection Shuffle

[simon]

That's a shame Steve. But if your heart's not in it there's no point if there's no fun. How about sitting on everything for 6 months and see how you feel then?

That said I'm tempted by the JJs - my RCAs are getting a bit gassy with age I guess. Must have been using them off and on for 10 years.

[Cressy Snr]

That's a shame Steve. But if your heart's not in it there's no point if there's no fun. How about sitting on everything for 6 months and see how you feel then?

Aye,
Might do that.
See how I get on with the speakers first.

[simon]

<Mike's big thumbs up emoji>

[jack]

I agree about not deciding on absolutes - give yourself some time - you're right in that you've nothing to prove (to yourself or anyone else) - quite right to question your own motivation.

Just noticed that the schematics are at the start of this thread. I learnt a lot from the original build - there is so much there that as a novice in these things, it got quite intimidating for me! Really appreciated the effort you (and others) put in to documenting the process.

[Cressy Snr]

The main problem, if you can call it that, is that you learn as you go, rather than having any inherent electronic skills other than the elementary algebra type as explained very satisfatorily by Morgan Jones in "Valve Amplifiers"
Armed with this knowledge, you can make an amp that will make a sound and you think that because you built it yourself, it is the bees knees.

Some of the stuff I used to come out with about how fantabulous the sound of my stuff was, is plain embarrassing when I look back at it. But interestingly, it all flows with an enthusiastic sense of the wonder of it all, a style that is now completely absent from anything I tend to write these days. In fact a lot of the written stuff I put out now reads a bit jaded and world weary and the (let's be honest for once) PITIFUL performance of my whizz-bang monoblocks at Owston only went to reinforce the notion that something has been lost on the way to where I am now. The stereo Barbarik (sorted out after visiting Colin's) that Paul now has, makes the monoblocks look like a sick joke I'm afraid.

They cost me a bloody fortune to build and are so full of bullshit it's unreal, and so misplacedly confident was I that they HAD to be the best, it produced a sort of blind arrogance about their abilities. They cost a lot of dosh, so they had to be better.

The classic hi-fi load of bollocks and brainwash, the Doc often rails against had got me in its grip about my own stuff, which is for me worse than believing the crap about the Linn Naim stuff. Christ, I was believing my own internalised hype!

Then 200 quid's worth of simple black box, 25WPC solid state amplifier, made by a controversial cantankerous old git was installed in my system and in the context of my own home system, so comprehensively did it walk all over anything I could have ever built (yes including that legendary 6B4G) that it was just game over. A serious wake-up call if ever there was one. And when I think of the money I have spent......no Stephen, dont for God's sake.

Now, to my credit (I believe that anyway) I have realised it is game over in that department and have been open-minded enough to accept that my DIY electronic stuff might be good, but it's not that good, if you get my drift.

I have stayed grounded where my speaker designs are concerned and as a consequence, the speakers, both omnis and Metronomes, actually do sound summat like, and I'm pleased with them and the reception (in the case of the Mets) they have had, both here and across the pond.

Now...here's the deal with tube amps. What I intend to do is to go right back to basics, strip out all of the "look how clever I am" bullshit and complication and just make a nice, simple, honest 2A3 SET and actually enjoy it for what it is....you know...ENJOY a great hobby and not tie myself in knots over it.

I'll quietly build it, once I've got the big omnis out of the way and just turn up at Owston with it and them next year; probably the best way to move forward.

[simon]

Makes a lot of sense Steve. Use the 12GN7s as triodes cap coupled to the 2A3s, LCLC PS. Nice coupling caps, nice 2A3s and nice OPTs and jobsagoodun.

If you fall in love with it again try the shunt reg PS, maybe DC reg the filaments. Maybe not bother. I use something similar to the above but with D3a and CCS load instead with the Quasars and it's 'good enough'.

[Cressy Snr]

Cheers Simon,
Something like the config you mention above, has to be the way to go really, doesn't it.
Valve amps are meant to be simple and simple is my intention from now on with these things.

[Paul Barker]

I totally agree and at risk of sounding like the Jasper Carrot "there is only one way to get rid of a mole" sketch.

May I suggest bin off the active power regulation. Do bare choke input. I would (and yes this is just me and an old fashioned notion) keep clear of the very high transconductance single stage driver. But also dont replicate the frequently used dual stage of same tube of a mu of 20 or so.

I would volt amp ta first stage with reasonably high mu tube something greater than 20 but less that 70 which counts out the 6sl7 ecc83 etc. But dont use the ecc88 its not got a quality sound imho. So I dont know whta you could use, but I'm sure you'll find something. driver stage give it to a triode connected el84. As Simon said go rc coupled with quality c.

All the fun of it went for me when I moved away from those sort of amps. But I am enjoying your Barbaric. You are not a failure or a fool, but you might be a bit bipolar.

Its obvious I too have had a later life crisis and given it all up, but maybe in support of you but at the very least for myself I too may build such a stripped down se amplifier just to see if we can recover the joy of the hobby. I promise I too will stera totally clear from active power supply intervention. But I shall use the transformer ripple rejection system as it is very bare and simple, and arguably if one can use the natural regulation of the choke input topology its just an extension of that philosophy.

I too will build it 2a3 powered but I reserve the right to make that with the 801a or the px4

[Cressy Snr]

I wouldn't say I'm bipolar, but it is very true that I have been going through a bit of a flaky patch over the past year with regards to my attitude to this hobby, and it has definitely had some kind of detrimental effect on my mental health. I think it's frustration rather than a feeling of failure that is the driver of the issue.

I agree with you Paul, that we need to try and recover the joy of this hobby, because when approached with the right attitude, it was and can once more be very rewarding.
I think Mr I was also alluding to the need to stop the bullshit and get back to the grass roots on another thread, but I can't remember which one now.

I'm glad you are enjoying the Barbarik. It is a far better amplifier than the monoblocks even though it is virtually the same idea but on a stereo chassis.

Thanks for the advice about simple power supplies and driving arrangements and I will look for a suitable setup for a voltage amp and driver stage. And thanks Simon also.

[simon]

Simple is good, in a number of senses. But component quality can be really important.

12GN7 is what I use to drive the GM70s, and that's the best amp I've built. But there may be better out there. I think I'd be using PX4s if I had them though Paul.

[Paul Barker]

shutup now ore youll have me building gm70.

[Cressy Snr]

Well,
From what I can find in the tiny stash of valves I have left, and a perusal of some sets of curves and using a three stage setup, I have found that triode strapped Thomson 6AU6 (mu of 36 and nice and linear in triode mode) driving triode strapped, JJ 6V6S (similar curves to EL84) driving JJ2A3-40, looks promising. I also found an old GEC A2900 (mu 60) lying in an old cardboard box that could (if it works) be used as the input stage; one less hole to put in the chassis.

Simple choke input supply to Eyuda oil-filled motor run caps, with AC for heaters and the 2A3 filaments.

Should get an authentic SET sound out of that.

[Paul Barker]

excellent choices. except ac 2a3 heaters will need some cancellation. that brings complexity and nervous edginess and throwing toys out of pram is at the end of that road for you and for me, as things stand in my life right now.

So you should compromise by using dc heaters for 2a3 I feel.

But if you want to go with S.Bench dht hum cancellation https://docs.google.com/document/d/18mp ... DHXFX4snIMI used circuit 3 in the link and it is sufficient hum cancellation for me, and the amp I used it on sounded good. No complaints. I would do it again.

[Cressy Snr]

I have a couple of DIYHS modules that'll do the filaments of the 2A3s, so no prob for DC filaments.

[Paul Barker]

Fine, while you were typing that I added a link but I suggest stick with the modules. Not a great idea to add complexity now.