Remember These?

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Nick
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Re: Remember These?

Post by Nick » Wed Oct 02, 2019 12:14 pm

Well it wouldn’t really steepen any load line, because the constant current sink in the cathode would give an essentially flat load line.
Don't forget the load. For AC a CCS in parallel with a AC load looks like a load not a CCS.
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Ray P
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Re: Remember These?

Post by Ray P » Wed Oct 02, 2019 12:18 pm

I'm questioning my memory now - I'll stick it into PSUD tonight to check it out.

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Re: Remember These?

Post by Cressy Snr » Wed Oct 02, 2019 1:20 pm

Ray P wrote:
Wed Oct 02, 2019 6:38 am
It's good to see you getting so much enjoyment out of this project Steve, both musically and as a DIY audio hobby....
Aye, it’s a very nice little project, and it does give beautiful sound. What’s more, it has proven to be thoroughly reliable.
It also responds positively and very audibly, to improvements to the power supply configuration. Separating the three stages from each other and giving them independent CLC supplies was a major step forward. Valve rectifying the input stage supply, put the icing on the cake.

I now think there isn’t any true dividing line, where the power supply ends and the amplifier begins; they are a single device and should be treated as one. I got a long way towards this way of thinking with the 6B4G monoblocks, and if I’d known then, what I know now, those monoblocks could have been something really special. Unfortunately, being an English graduate rather than an electrical engineer I learn (in this particular field at any rate) by osmosis and trial and error, so the road to enlightenment is quite a bit longer than it is for most electronics hobbyists. :)

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Re: Remember These?

Post by Nick » Wed Oct 02, 2019 3:48 pm

I now think there isn’t any true dividing line, where the power supply ends and the amplifier begins
Why would you expect there to be a distinction. The amplifier and power supply are both parts of a system, what you are describing are just words we use to think about the thing, the map is not the territory.
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Re: Remember These?

Post by Cressy Snr » Wed Oct 02, 2019 4:18 pm

Nick wrote:
Wed Oct 02, 2019 3:48 pm
I now think there isn’t any true dividing line, where the power supply ends and the amplifier begins
Why would you expect there to be a distinction. The amplifier and power supply are both parts of a system, what you are describing are just words we use to think about the thing, the map is not the territory.
Hi Nick,

It’s the way I think (wrongly it turns out) about things, and it can be rather frustrating; both for myself and the people who have to read the drivel I often put out. I have had amps and power supplies down as separate entities since I started. You work out the audio side, then you work out how you’re going to power the thing.

I now realise (better late than never) that the audio is the easy bit; the power supply and the grounding scheme, takes a damned sight more thinking about. From the results I have with this OTL, the PSU is the difference between a good amplifier and a great one. And I’ll stick my neck out and say that yes...this single tube OTL is now an excellent amp, and one with the potential to be absolutely outstanding.

Yes...I appreciate that in the eyes of the mathematicians, systems analysts and engineers among us, this power supply stuff and its importance, shouldn’t need to be explained to people when they are 15 years down the line. :oops:

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Re: Remember These?

Post by IslandPink » Wed Oct 02, 2019 6:22 pm

Cressy Snr wrote:
Wed Oct 02, 2019 1:20 pm
I got a long way towards this way of thinking with the 6B4G monoblocks, and if I’d known then, what I know now, those monoblocks could have been something really special.
Crikey, your standards must be really high ! :)
"The bass is the king of the instruments - it has no known natural predator" (Wobble)

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Re: Remember These?

Post by Cressy Snr » Wed Oct 02, 2019 6:48 pm

IslandPink wrote:
Wed Oct 02, 2019 6:22 pm
Crikey, your standards must be really high ! :)
Possibly; but there were some things that those monos didn’t do right. They were undeniably superb on simple music and acoustic jazz, but got a tad confused, uncouth and breathless on more complex tracks. That said, they did quite well with System 7 at Owston, but it’s difficult to tell with electronic music, what is ‘fault, and what is ‘effect’
Bass, seems to be the least affected by single channel power supplies when running SE amps; especially when said supplies are regulated. Instead it’s the midrange and treble that goes all to cock. Mids get all shouty, transients blur and top end textures fuzz out.

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Re: Remember These?

Post by Ray P » Wed Oct 02, 2019 8:32 pm

So a quick check in PSUD2 suggest I'll have a nice clean B+ of around 137V with an assumed load of 500mA and my recollection of around 20V was about right. The transformer parameters are measured/correct but I took a flyer on the cap resistances but it won't be far out. I assumed a mains voltage of 240V but we typically run a couple of volts above that.
PSUD2 - power supply sim.PNG

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Re: Remember These?

Post by Ray P » Wed Oct 02, 2019 8:40 pm

Apologies Steve, its dawned on me that I've been a bit rude and clogged up your thread. :oops:

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Re: Remember These?

Post by Cressy Snr » Wed Oct 02, 2019 8:45 pm

Ray P wrote:
Wed Oct 02, 2019 8:40 pm
Apologies Steve, its dawned on me that I've been a bit rude and clogged up your thread. :oops:
No worries Ray,
I’ve clogged it up myself, with enough nonsense to sink a battleship.You could remove three quarters of the posts and the thread would make far better sense. At least you’re putting up stuff that actually means something :lol:

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Re: Remember These?

Post by Ray P » Thu Oct 03, 2019 6:22 am

Cressy Snr wrote:
Wed Oct 02, 2019 8:45 pm
I’ve clogged it up myself, with enough nonsense to sink a battleship.
I think you're being hard on yourself Steve. I, for one, have enjoyed your journey and wouldn't want you to change anything. Keep being you.

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Re: Remember These?

Post by Cressy Snr » Thu Oct 03, 2019 10:22 am

Ray P wrote:
Thu Oct 03, 2019 6:22 am
I think you're being hard on yourself Steve. I, for one, have enjoyed your journey and wouldn't want you to change anything. Keep being you.
It isn’t really me Ray; at least, not entirely. Over the years, this monster has been created, that should have been killed off, like Ziggy, a long time ago. I love building things. I no longer really enjoy writing about the process. There’s only so much one can say before it becomes tedious if I’m being completely honest. I’ve written about 51 amps in 15 years so that seam is probably long since exhausted.

Anyway, the OTL and the Fanes are providing plenty of great sounds and some thoroughly enjoyable music listening. That’s as far as I’m going with the purple prose for now. Folks will have to tell me what they think in June next year. :wink:

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Re: Remember These?

Post by Cressy Snr » Fri Oct 04, 2019 11:57 am

OK,
Final round up of the amp specs:

Three independent stereo power supplies, serving preamp stage, driver stage and power stage.

Preamp stage - Valve rectified by hybrid bridge. EZ80, into 22uF-4H-220uF, CLC

Driver stage - Valve rectified by hybrid bridge. GZ34, into 40uF -10H-100uF, CLC

Power stage - solid state, 25A bridge rectifier, into 2200UF - 0.032H - 2200uF, CLC.

That’ll do very nicely thank you. :)

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Re: Remember These?

Post by Ray P » Sat Oct 05, 2019 6:20 am

Steve, I suspect even the largest size will be too small for your transformer but I thought I would point these out to you just in case;

https://www.ebay.co.uk/itm/Metal-Shield ... 2749.l2649

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Re: Remember These?

Post by Cressy Snr » Sat Oct 05, 2019 10:36 am

Ray P wrote:
Sat Oct 05, 2019 6:20 am
Steve, I suspect even the largest size will be too small for your transformer but I thought I would point these out to you just in case;

https://www.ebay.co.uk/itm/Metal-Shield ... 2749.l2649
Thanks Ray, the largest is indeed too small for the main transformer, but they are worth using for another project I’m collecting the bits for. I’ve bookmarked the page.

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