pt15

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ed
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pt15

Post by ed » Mon May 20, 2013 5:58 pm

I was raking over my aikido stuff for another thread when I came across some notes I'd taken from John Broskie's site many moons ago....it was for a PP PT15 amp driven by an aikido front end, which JB said sounded like PX25....mmmm

anyways, my memory says that a few here built PT15 amps and they were cheap and plentiful.........

not anymore..where have they all gone!!!

or is it a memory fault again, and they were never cheap or plentiful
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Paul Barker
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Post by Paul Barker » Mon May 20, 2013 6:12 pm

It must be scarcity value.

Trouble is back then you could ring Rod Eliot or Jim Fish and place your order and they would send you excellent boxed tested valves like this for maybe £20.

Jim retired and I think Rod has sold up. Derek Roco never stocked this type of valve.

That leaves too few dealers so Colomore has cornered the market and is making shure his remaining stock of this type of thing which he can only sell once, goes at a good price. I can't blaim.

I said to Mike (I think it's his son) a few months ago, "what do you think will happen to our valves?" (What I meant by that was will they suddenly devalue as there becomes no demand, a day I do anticipate) he said "we will run out!"

Stocks are low, so prices have to be high as nobody knowing they cannot replace their stock will sell cheaply.

So I would leave such scarce valves to the folk who actually need them for their intended purpose and play with stuff made by the Russians, as you already have.

It is a crying shame that Svetlana didn't continue. You will be more aware than me of the scarcity of their excellent transmitting triodes. If I had only known in advance I would have stocked up on such as you use.
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Post by Paul Barker » Mon May 20, 2013 6:15 pm

One valve of the type you speak which I truly must try is the CV57 Colomore used to state it was like a px25 triode connected.

Could be smoke and mirrors. But we need to find out. I have at least two may have three.
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Post by Paul Barker » Mon May 20, 2013 6:33 pm

Interesting the cv57 if you look at the data sheet in this ebay sale

http://www.ebay.co.uk/itm/Matched-4pcs- ... 3ccc4df9e1

Possibly would be worth trying triode connected.

Seems to have a centre tapped filament with a kathode tap off it. Probably similar to the 6A57G

I have always had a pair and can't detect a difference in sound between these and the 6a3.

We used to discuss it and we decided because it sounds so good it is actually direct heated but the filament is centre tapped and that is the kathode connection.

I can believe that.

But that was before Guido Tent and all the follow on hispec dht heaters when ac heating was something to be sawt. (sorry Ed I have no chance of spelling that word.)
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Post by Paul Barker » Mon May 20, 2013 6:36 pm

Someone has realised how nice 6a5g's sound by the look of it. When I bought my pair people were turning their noses up at them. Dam, should have got more!

http://www.ebay.co.uk/itm/Matched-pair- ... 484c1c4592
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Post by pre65 » Mon May 20, 2013 6:47 pm

I've got four PT15 if you are interested Ed. :)
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Post by ed » Mon May 20, 2013 7:47 pm

Thanks Phil, but no thanks. my original question was rhetorical. Paul has summed up my feelings entirely vis chasing builds with valves that are disappearing...can only end in tears.....I have enough pairs of svets to see me through...

my money is on the SIC/SIT developments. You build an amp and it lasts forever, the little plastic chaps never wear out.

I have one spare set of valves for my 2A3 at the mo and when they wear out, if my finances don't change, then the amp is junk. So there are always different ways of looking at it.
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Post by Cressy Snr » Mon May 20, 2013 9:05 pm

Aye... this business of ever dwindling stocks of the old valves is one reason, why I'm striving so hard (thankfully with some success) to build good sounding amplifiers that use current production power valves.

Small signal valves such as 12AT7s, (ECC81) which make really nice drivers for push pull pentodes are still reasonably cheap NOS, but ECC83 Mullard/Telefunken, is virtually extinct and ECC82 are fast following them, with commensurate high prices being asked. Even 5687s have tripled in the last couple of years.

7pin miniatures, such as the 6AQ5 (EL90) are still very cheap and IMO if parallelled up in push-pull would make stunning little 20 watters. It'd be nice to drive them with DCC90 (3A5) miniature battery valves, cheap also. Finding a way to heat their 1.5V filaments is the problem.
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andrew Ivimey
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Post by andrew Ivimey » Mon May 20, 2013 9:07 pm

There's loads of 2A3s out there and those Shuaguang 2A3cs really are very nice. I've got loads of all sorts of 2A3s (but alas no single plate originals) but its a good place to be. I like it.

OTOH, I have quite a few PT15s and the odd pair of strange oddities all directly heated. I have more than I'll ever get through so ooooppps I'll never get through to them all - silly me!

Still there's loads of fun to be had and those PT15s (I have a PT15 amp gathering dust) and if I don't get round to it well, ca vas.

But I'd like to, and run the HT up a bit to push the envelope. They are nice as is but I like to feel the heat.

Which brings me back to Paul (oops I've just bought a pair of honkger triodes) but on the whole I agree... those rushin valves are so cheap and so exciting. He has heard (chinese) 50s you know and they weren't so good. And then he has heard some chinese 211s and he was surprised/impressed becasue what he heard before were rubbish. We can all agree they aren't vt4cs and the HT was slightly less than 1kVolt but they are stupidly cheap and I have one pair left which I keep for reference.

What are we going to do when all the NOS run out? I don't care that much as I will have had a lot of fun with my modest hoard. But I will also have thoroughly enjoyed the music.
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Post by ACPEN » Tue May 21, 2013 3:04 pm

Not sure if it's been mentioned before but the 1624 is a cheap DH pentode - looks like an 807 with an octal base (£10 from Langrex) or the 1619 (Octal) very similar at £8.00! They are both 2v @ 2.5A filaments. So easy switch from a 2A3!

ATB,

David.

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Post by ACPEN » Tue May 21, 2013 6:13 pm

Ooops! 1624 same base as 807, AND 2.5v 2A - but, you knew that anyway!

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Post by IslandPink » Tue May 21, 2013 9:29 pm

Eimac 35T's are available for £20-25 per valve and I even saw a pair for £13 on Ebay when I was looking ( not matched ) . That would make an ace project for someone if you ask eg. Paul or Nick for ideas on a cheap A2 driver.
On small signal valves and driver options there are so many obscure types out there I don't see that there's any shortage of good options for the future.
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Re: pt15

Post by MSound » Fri Apr 22, 2016 7:49 pm

Good Day!
Can anybody, please, the schematics SE PT15 postet?
I'm looking for especially James Doddingtons circuits.
Thank You!!!
Regards,
Leon

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Re: pt15

Post by pre65 » Fri Apr 22, 2016 9:19 pm

Hi, I posted a copy of James Ds circuit on World Designs forum. :)
People are like stained-glass windows. They sparkle and shine when the sun is out, but when the darkness sets in, their true beauty is revealed only if there is a light from within
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Re: pt15

Post by MSound » Fri Apr 22, 2016 10:48 pm

Unfortunately, all the information there is not available (deleted?).

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