‘bout time I listened to 46

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Paul Barker
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#1 ‘bout time I listened to 46

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#2 Re: ‘bout time I listened to 46

Post by Paul Barker »

Shouldnt encounter grid current at 46 grid so I can stack small PV waifer,s built in a light proof environment so I can control the level.

Very simple construction. I need to set a simple goal and actually achieve that goal. Obviously hard to make -33v exact, Ill fall short and complete the bias with very small un-bypassed cathode resistance, which may occur through the hum pot.

I dont know any better that Stephie how to do things so as Im in a mental state where I’d never get out of the cycling wild ideas stage, hence going with Stephie’s triode connected D3a.
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#3 Re: ‘bout time I listened to 46

Post by Paul Barker »

I’m assuming Steve will let me bring it to listen on his super efficient speakers, in Steve’s listening room 1 watt is loud.
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andrew Ivimey
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#4 Re: ‘bout time I listened to 46

Post by andrew Ivimey »

Wow, minimal. I like it!
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#5 Re: ‘bout time I listened to 46

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andrew Ivimey wrote: Sun Aug 29, 2021 10:08 am Wow, minimal. I like it!
Thanks for youre support Andrew. I would love to pick up on Mark’s experiences with D3a pentode mode, but the triode mode just screams “interstage couple me”, no Im not hearing voices!
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#6 Re: ‘bout time I listened to 46

Post by Nick »

Not sure what the PV provided bias gives in terms of problems solved?
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#7 Re: ‘bout time I listened to 46

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I know, was talking to Neal at a gathering about using it for b+. I said “we don’t know what it sounds like”!

Remembering that day in you’re listening den when you suggested my lead acid battery bias and compare it to resistor bias. I learned that day the batteries sounded bad and have never gone back to them.

I’m doing this because I want to find out what it sounds like.
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#8 Re: ‘bout time I listened to 46

Post by IslandPink »

Paul Barker wrote: Sun Aug 29, 2021 1:01 pm Thanks for youre support Andrew. I would love to pick up on Mark’s experiences with D3a pentode mode, but the triode mode just screams “interstage couple me”, no Im not hearing voices!
I think for a power amp you'd be battling too much gain with a D3a in pentode mode, same as the 12GN7 which I found a bit troublesome. The transconductance, limited dissipation and likely B+ would force an anode resistor that would give too much gain. That's why C3m is quite a good choice , less Gm. I eventually went to DHP with the 4P1L which to be honest is a bit low in gain for many systems, but my speakers are fairly efficient. The extra current and direct heating seems to give the best transparency and midrange tone that I've had.
Anyway, will be good to see how this one works out. What is the interstage ?
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#9 Re: ‘bout time I listened to 46

Post by Paul Barker »

I can’t off hand say model butt Hammond bifilar 1:1

I have a pair AE bifilar but if I mount those they take too much chassis room up and their current capability well in comfort zone.
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#10 Re: ‘bout time I listened to 46

Post by steve s »

Paul Barker wrote: Sun Aug 29, 2021 8:51 am I’m assuming Steve will let me bring it to listen on his super efficient speakers, in Steve’s listening room 1 watt is loud.
Of course Paul, your always welcome
I have a pair of ST 46's somewhere too..
Be good to hear them
Get it built up quick on a bread board !
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#11 Re: ‘bout time I listened to 46

Post by Paul Barker »

Cool
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#12 Re: ‘bout time I listened to 46

Post by RhythMick »

I'll have a look through my boxes. I have a nagging thought that I may have a pair of Cunningham globe 46.
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Paul Barker
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#13 Re: ‘bout time I listened to 46

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"Two things are infinite, the universe and human stupidity, and I am not yet completely sure about the universe." – Albert Einstein
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#14 Re: ‘bout time I listened to 46

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Ooh
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#15 Re: ‘bout time I listened to 46

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I oriented the D3a base same as EL84 but that put both D3a’s different to each other and different to EL84. Anyway, whose to say the EL84 won’t in future occupy those bases and the BRitish 5 pin valve might not provide the gain. I have the base ready for that, or for ending up modifying amp to px4.

You never know, but first iteration, let’s find out about the 46.

I’m going to have to either make a variable bias supply or if my surplus b+ before I tame it, have selectable bypassed cathode resistors. After I’ve hooked up power supply I’ll know better.
Last edited by Paul Barker on Mon Aug 30, 2021 2:24 pm, edited 1 time in total.
"Two things are infinite, the universe and human stupidity, and I am not yet completely sure about the universe." – Albert Einstein
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