New SE With Triode Mode KT120/150

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JamesD
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#226 Re: New SE With Triode Mode KT120/150

Post by JamesD »

Or the primary circuit...

but I prefer the secondary circuit in case of a transformer fault it limits the possible fault current through the rectifier circuit... rare I know but not unheard of...
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Nick
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#227 Re: New SE With Triode Mode KT120/150

Post by Nick »

JamesD wrote: Wed Aug 05, 2020 3:42 pm Or the primary circuit...

but I prefer the secondary circuit in case of a transformer fault it limits the possible fault current through the rectifier circuit... rare I know but not unheard of...
Agreed, but I was just pointing out that the primary side also plays a role in the source seen by the rectifier.
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Paul Barker
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#228 Re: New SE With Triode Mode KT120/150

Post by Paul Barker »

IslandPink wrote: Wed Aug 05, 2020 12:23 am
Paul Barker wrote: Tue Aug 04, 2020 10:09 pm I only build choke input power supplies, is that clearer?
Hang on - you built a Steve Bench shunt-regulated power supply - did you not like that one ?
ive built three and next will be 4th.
They’re all choke input, a capacitorless supply can’t have a capacitor in it.
Last edited by Paul Barker on Wed Aug 05, 2020 7:20 pm, edited 1 time in total.
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#229 Re: New SE With Triode Mode KT120/150

Post by Cressy Snr »

simon wrote: Wed Aug 05, 2020 1:37 pm There used to be a couple of guides on how to use PSUD knocking around on the net, I'll see if I can find them.
That might be rather helpful. :)
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Paul Barker
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#230 Re: New SE With Triode Mode KT120/150

Post by Paul Barker »

Paul Barker wrote: Wed Aug 05, 2020 7:17 pm
IslandPink wrote: Wed Aug 05, 2020 12:23 am
Paul Barker wrote: Tue Aug 04, 2020 10:09 pm I only build choke input power supplies, is that clearer?
Hang on - you built a Steve Bench shunt-regulated power supply - did you not like that one ?
ive built three and next will be 4th.
They’re all choke input, a capacitorless supply can’t have a capacitor in it.
I think Stephie called them RR or was it LR ? Can’t recall but choke input is part of the better sound. Valve shunt reg after all the L’s is bigger part of it and no capacitors is the final enhancement over all other supplies I’ve made. As I’ve said before I added capacitor one by one of all types including wkz and they all made it sound considerably worse.
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#231 Re: New SE With Triode Mode KT120/150

Post by simon »

I've found one of them Steve - it's by DHTRob and was originally in Bas Horneman's Christmas 2005 DIYMAG I think. Not sure they're available anymore, but the article is on DHTRob's website here:

https://www.dhtrob.com/overige/pdf/dhtrob_psu.pdf
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#232 Re: New SE With Triode Mode KT120/150

Post by Cressy Snr »

simon wrote: Wed Aug 05, 2020 10:58 pm I've found one of them Steve - it's by DHTRob and was originally in Bas Horneman's Christmas 2005 DIYMAG I think. Not sure they're available anymore, but the article is on DHTRob's website here:

https://www.dhtrob.com/overige/pdf/dhtrob_psu.pdf
I’ve been talking about the power stage supply mostly on this thread, but the pre/driver stage supply, is built on very similar lines to the example he talks about in the article. Using the simulations on my Mac, I got the capacitance in my own pre/driver supply way down, without any increase in noise. Good to see I’m on the right lines in that respect. But it was more iterative on my part, and arrived at more by luck than judgement.

Thanks Simon. That article is going to build up my knowledge nicely.
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#233 Re: New SE With Triode Mode KT120/150

Post by simon »

I've found the driver stage to be surprisingly important to the sound and have a separate supply for the 12GN7 driving my GM70 amp - think we're on the same page with this Steve :D
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#234 Re: New SE With Triode Mode KT120/150

Post by Paul Barker »

Sounds nice Simon
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#235 Re: New SE With Triode Mode KT120/150

Post by simon »

Yep. You've heard it at mine a few years back Paul.
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Paul Barker
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#236 Re: New SE With Triode Mode KT120/150

Post by Paul Barker »

Lovely session in your Doncaster house when we talked about the bridge they were fixing. You’ve moved I think u said since then?
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#237 Re: New SE With Triode Mode KT120/150

Post by simon »

No still in the same place, don't even want to think about moving again <shudder>. No idea which bridge that would have been, could have been one of many.
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#238 Re: New SE With Triode Mode KT120/150

Post by Paul Barker »

No matter. Maybe I’ll bring Matrix one day.

But stalled at power supply materials. The power supply chokes I’m going to need would be very costly and I’m broke for temporary. I’ll probably order some EI 120 laminations and wind my own. The u19’s will require 600 ohm resistance and I’d rather not just buy resistors but make sure all the chokes add up to 600 ohm. They’ll have to handle 250mA with two parallel chains of chokes so the shunt reg can shunt as much as the matrix required for signal. I.e power supply has to handle 500 mA. So all chokes have to be big.

No point building signal section power supply is first. The b+ is very simple but demanding heavy obviously.

Then all the other voltages stem from it except the negative bias. The LR power supply is looking like it’ll end up at around 900v Stephie wants 800 but it makes no matter because you’re on a horizontal section of the gk71 curves meaning no need to alter anything to run it at 900v instead of 800v. 400v g2 will be pulled off the vr string. The VA will be paired off that as will that stages g2.

Enough to keep me from boredom for a while.

You may have to wait years. Hope we’re all around. I’ve got everything I need except time and more big heavy chokes.
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#239 Re: New SE With Triode Mode KT120/150

Post by simon »

Time - the enemy of so many of us. And enough of the right iron. Would be great to hear it one day.
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#240 Re: New SE With Triode Mode KT120/150

Post by Cressy Snr »

Badge added to front of amp:
Both contributors named :wink:
865C04FB-8522-4CA2-AE41-045E60706BD8.jpeg
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