Single-Ended Pentode Redux

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Paul Barker
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#31 Re: Single-Ended Pentode Redux

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Rolling on the floor in stitches at that final comment. You're sense of comedic timing in the whole post is as good as any of the great non politically correct comedians of yester-year. Salute my friend.

Pretty sure I have one or two UK ruggedised military Mullard ECC81’s. If I find one Ill send it so you can compare to that one. These also sell for triple figures. Scary.

To be fair to the guy who obviously thinks tube rolling is madness. Majority of humans dont get us!
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#32 Re: Single-Ended Pentode Redux

Post by Cressy Snr »

:D
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#33 Re: Single-Ended Pentode Redux

Post by Thermionic Idler »

Cressy Snr wrote: Fri Jan 14, 2022 7:23 pm Yes, I think the 6V6 SEUL with Schade feedback is certainly a definite candidate for putting in a proper enclosure. That's three amps then:

2W DHT SET
4.5W 6V6 SEUL
60W solid state with built-in phono stage.

Quite a productive and enjoyable few weeks. Lovely.
Valve buffer for the NVA thingy anyone? :)
How about adding a directly heated pentode amp to that list? (Type 47).

I didn't even know directly heated pentodes were a thing until this showed up on my Youtube feed...

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Phono: Pete Millett LR, Lundahl SUT, AMB σ22 PSU
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#34 Re: Single-Ended Pentode Redux

Post by Thermionic Idler »

andrew Ivimey wrote: Thu Jan 13, 2022 6:41 pm I only have a few Brimar 6V6s but would like to hear how the cheap Russian ones sound.
Pretty lifeless when used as 300B push-pull drivers, I bought a matched quad and took them out after a day, it was like the Dementors had descended. I currently have old-stock Tung-Sol, much better. That said, at the time I was running them with less current, they might wake up a bit at the 35mA I'm running them at now.
Last edited by Thermionic Idler on Sun Jan 16, 2022 7:31 pm, edited 1 time in total.
Deck: Garrard 301 - Audio Origami PU7 - NW Analogue DH3S
Phono: Pete Millett LR, Lundahl SUT, AMB σ22 PSU
Linestage: Bruno Putzeys Balanced Pre + Hans Polak relay mod, LCDuino control
Power amps: 300B PP 'Symmetric Reichert'
Speakers: FF225WK Big Mets
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#35 Re: Single-Ended Pentode Redux

Post by Thermionic Idler »

Cressy Snr wrote: Fri Jan 14, 2022 5:56 pm I have a pair of NOS, French Mazda 6V6 from the 1950s in the amp at the moment and they are lovely.

I have 2 NOS black glass Brimar and 2 grey glass Sylvania, plus a pair of new production JJ 6V6S, so plenty to be going on with.

A nice, sweet and detailed 4 and a bit Watts or so, vs the 9..ish Watts of KT77. The 6V6 in ultralinear Schade config is quite close to a 45 soundwise.
Steve - I'd be interested on your thoughts on the sound of the JJ 6V6 versus the old stock ones - I've only ever used old stock in the 6V6 driver position of my 300B's, but have been pondering trying some new JJ's as I think one of the ones in there at the moment is going weak.
Deck: Garrard 301 - Audio Origami PU7 - NW Analogue DH3S
Phono: Pete Millett LR, Lundahl SUT, AMB σ22 PSU
Linestage: Bruno Putzeys Balanced Pre + Hans Polak relay mod, LCDuino control
Power amps: 300B PP 'Symmetric Reichert'
Speakers: FF225WK Big Mets
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#36 Re: Single-Ended Pentode Redux

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Thermionic Idler wrote: Sun Jan 16, 2022 7:30 pm
Steve - I'd be interested on your thoughts on the sound of the JJ 6V6 versus the old stock ones - I've only ever used old stock in the 6V6 driver position of my 300B's, but have been pondering trying some new JJ's as I think one of the ones in there at the moment is going weak.
I’ll try them and report back tomorrow Dave. :)
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#37 Re: Single-Ended Pentode Redux

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Thermionic Idler wrote: Sun Jan 16, 2022 7:14 pm
Cressy Snr wrote: Fri Jan 14, 2022 7:23 pm Yes, I think the 6V6 SEUL with Schade feedback is certainly a definite candidate for putting in a proper enclosure. That's three amps then:

2W DHT SET
4.5W 6V6 SEUL
60W solid state with built-in phono stage.

Quite a productive and enjoyable few weeks. Lovely.
Valve buffer for the NVA thingy anyone? :)
How about adding a directly heated pentode amp to that list? (Type 47).

I didn't even know directly heated pentodes were a thing until this showed up on my Youtube feed...

Some of these sparcely knowledgeable you tubers make me think of an old expression long gone rusty, kids and loaded guns spring to mind.
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#38 Re: Single-Ended Pentode Redux

Post by andrew Ivimey »

Skunky Designs. .... made me smile!
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#39 Re: Single-Ended Pentode Redux

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pre65 wrote: Fri Jan 14, 2022 7:27 pm
Cressy Snr wrote: Fri Jan 14, 2022 7:23 pm Yes, I think the 6V6 SEUL with Schade feedback is certainly a definite candidate for putting in a proper enclosure. That's three amps then. Lovely.
IF I had UL output transformers I'd be tempted. :wink:

But, I don't need any more amps, my one remaining ambition is to get the revamped 833a up and running. :)
Good idea, one thing I like about the 833a is it does what lower powered amps do best, compared to most other transmitting valves, better than the niche low powered valves. Unlike the 211 for instance, which in its environment sounds good and never lets you down but it doesnt shine anywhere else. As soon as an 833a amp starts playing you have no messing, big brother is showing how great he sounds low level too.
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#40 Re: Single-Ended Pentode Redux

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I am also quite pleased Steve has popped a 6v6 in, with me building a Raymond Bates. I cant give Bates my best effort because I dont see any point taking my nice 5k opt’s from the 801a PSE. So was looking at other 5k opts I could get.

But wife nagging was getting to a pitch last few days, and online purchases were consistently targeted in the moaning carping criticism.

So Im going to have to order nothing more for the present. This puts me with two options, use the 3k into 8 ohm se Rcores, or cease building.

So my efforts with Bates might not show the true sounds available from 6v6. But I have in my memory bank that day, no those few days, I sat endlessly in Bruce Edgar’s room at vsac hearing flawless sound. The focus was the speakers, the talk was all Dr Bruce, you couldnt get a word in edgeways, but on reflection I had nothing to say. Now noone can sit with Dr Bruce I am so glad I shut up and listened for the duration.

I think I only managed to extend his pause for breath to allow a question once and I prized it wide enough to discover what amp he was using. The only words from his mouth were “a little 6V6 cathode follower amp these guys made for me”.

Listen Ive never heard anything that comes anywhere near that experience.

So Edgars Tightans are done and dusted for me. Shame I dont have the money required or the Nut behind the wheel any more.

So one of the influences that made me pick up the Bates article was that!

Anyway compromises dont necessarily kill projects. But they slow them down as you have to use youre imagination a lot more. Simplest way is take the 801a power supply (choke input, Black Gates 608vdc 250mA output), and simply series pass reg it to serve as a “bench power supply” for sub 600v projects going forwards. have enough 6080’s, the nech supply element would go in a decent sized Class II Adaptable Box which receives the 608v and sends out the voltage required for whatever project it is this time! That would be the simple way. But you know me!

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#41 Re: Single-Ended Pentode Redux

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Paul Barker wrote: Mon Jan 17, 2022 9:30 am I am also quite pleased Steve has popped a 6v6 in, with me building a Raymond Bates. I cant give Bates my best effort because I dont see any point taking my nice 5k opt’s from the 801a PSE. So was looking at other 5k opts I could get.

Why not make the OPT's a separate item (like I do) then you can use them with more than one amp.

Makes the amp a bit lighter as well. :wink:
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G-Popz THE easy listening connoisseur. (Philip)
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#42 Re: Single-Ended Pentode Redux

Post by Cressy Snr »

This is where we are at the moment:
6V6SEUL+Schade.png
6V6SEUL+Schade.png (55.8 KiB) Viewed 1972 times
A tweak to the cathode bypass cap value on the output valve enables 6V6 operation.


6V6PSU.png
6V6PSU.png (56.8 KiB) Viewed 1972 times
Power supply.
Hybrid rectifier, but that's the norm these days when you are using what you have in the parts bin, and never had any old iron from the heyday.
Mains transformer is a 220VA, Antrim potted toroidal I bought years ago, from Andrew L. It's completely silent in operation, indeed the whole thing is silent, absolutely zero hum, of either the electrical or the mechanical variety. I've never built a valve amp with this kind of inky black background before.
I hope it stays as quiet when it goes in a box.
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#43 Re: Single-Ended Pentode Redux

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Thermionic Idler wrote: Sun Jan 16, 2022 7:30 pm Steve - I'd be interested on your thoughts on the sound of the JJ 6V6 versus the old stock ones - I've only ever used old stock in the 6V6 driver position of my 300B's, but have been pondering trying some new JJ's as I think one of the ones in there at the moment is going weak.
Right!
JJ 6V6S are very good indeed. Nice fat bass and more extended treble compared to the old Brimar, Mazda and Sylvania. Some people think they have a hint of the 6L6 presentation in the sound they make. I was quite impressed with them TBH. They sound slightly different to the older valves but this is by no means a criticism of them. They are just as valid a proposition as the old ones, in my amp at any rate.
Last edited by Cressy Snr on Mon Jan 17, 2022 2:35 pm, edited 2 times in total.
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#44 Re: Single-Ended Pentode Redux

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It’s good but because the 801a is done dusted, delightful and proved reliable as daily used since Owston I don’t want to plunder it.

When I’m semi retired I’ll sort out transformer winding again. I bought a Chinese AVO knock off but it’s not Chinese Engineerings finest hour, all bars the cogs are rotated and traversed via, is ofcentric buckled and looks like the Scarborough goalie after the match with Chelsea.

Edit, this post makes sense if you knew I thought I was quoting Phil’s last post, but I wasn’t! The story of my life.

Edit, Very pleased to hear you already have a good result Steve!
Last edited by Paul Barker on Mon Jan 17, 2022 2:41 pm, edited 1 time in total.
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#45 Re: Single-Ended Pentode Redux

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Paul Barker wrote: Mon Jan 17, 2022 8:58 am Good idea, one thing I like about the 833a is it does what lower powered amps do best, compared to most other transmitting valves, better than the niche low powered valves. Unlike the 211 for instance, which in its environment sounds good and never lets you down but it doesnt shine anywhere else. As soon as an 833a amp starts playing you have no messing, big brother is showing how great he sounds low level too.
I find that an interesting observation Paul.. and I echo your thoughts about the 211.

I suppose that could be seen to contradict the view that the detailed, sweet sound of many low powered valves is down to higher levels of 2nd harmonic content..
..which in turn to me, doesn't quite seem like an adequate explanation.
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