The Newton 300B

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Thermionic Idler
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#136 Re: The Newton 300B

Post by Thermionic Idler »

izzy wizzy wrote: Tue Feb 16, 2021 7:21 pm
Thermionic Idler wrote: Tue Feb 16, 2021 7:06 pm Ah yes, I've been looking at the uTracer. Also the eTracer which has enough -ve bias to measure the 300Bs but it's ... a bit spendier.

The Raytheon 6V6's went back in tonight, I couldn't take any more. Aaaaaaand as if by magic... the music's back! :D

I thought it would be something I'd have to listen carefully for. Nope, even Meredith who was in the kitchen area prepping the chicken and not listening particularly closely, could hear the difference in the first few seconds.

So now to find a matched set of Raytheons. Although I'm not sure whether to stick with those or try Sylvanias, which I've always liked for *SN7 valves. The problem is the 6V6 is used primarily as a guitar amp valve, so most of the opinion out there is from guitarists operating them at the ragged edge.
Good result. I'm no guitarist but don't those folk like tone? So not a bad recommendation for starters? Not all are on the "ragged edge" AFAIK.
Good point, and it's specifically that which I've been paying attention to when reading the various write-ups. A lot of them also seem to like the current issue Tung-Sol too.

I do wonder why NOS valves sound better in general - surely if these things are operating to specification it shouldn't make any difference? Or is that the problem right there?
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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#137 Re: The Newton 300B

Post by steve s »

It's all in the metals Dave, they knew what they where doing pre war, remembered most of it post war, then
when production went abroad no one cared, I think they are getting better at making them, but they are starting to charge for it too.
Last edited by steve s on Wed Feb 17, 2021 1:10 pm, edited 1 time in total.
The tube manual is quite like a telephone book. The number of it perfect. It is useful to make it possible to speak with a girl. But we can't see her beautiful face from the telephone number
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Nick
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#138 Re: The Newton 300B

Post by Nick »

I think there is also an aspect that just being older means the structures of the valve have had longer to "relax" in the same way that cryo treatment seems to.
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#139 Re: The Newton 300B

Post by Ali Tait »

I had some cryoed Shuguang EL34 that sounded better than NOS RFT’s.
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#140 Re: The Newton 300B

Post by steve s »

Ali Tait wrote: Wed Feb 17, 2021 1:23 pm I had some cryoed Shuguang EL34 that sounded better than NOS RFT’s.
That's interesting Ali, I wonder if it works with 300b's.. or my be that why the are sounding better than those made 20 years ago, they do it as a matter of course.
The tube manual is quite like a telephone book. The number of it perfect. It is useful to make it possible to speak with a girl. But we can't see her beautiful face from the telephone number
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#141 Re: The Newton 300B

Post by Thermionic Idler »

No idea what time I went to bed last night. After Ms Idler had turned in post-evening TV, I stayed up to listen to some records with the lights off. Completely lost track of time. I'm liking these amps but they are bad for my health!

I kinda wish the 300B's glowed more, but my operating point rules out mesh plates. That said, there is a nice blue glow on the glass, although that can only be seen in darkness. Probably near-impossible to capture on camera.

I'm starting to think I might also leave the 6V6 operating points where they are - that tiny difference in 3rd order distortion from the theoretical model would probably be swamped by variance between valves, and dropping the current might affect the drive to the 300B's. It sounds so good that right now I'm disinclined to mess with it any further, other than the inevitable valve rolling. All valves are running quite conservatively (provided the 12SN7 is a GTA type) so I hopefully should get good tube life as well.
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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#142 Re: The Newton 300B

Post by Ali Tait »

steve s wrote: Wed Feb 17, 2021 4:10 pm
Ali Tait wrote: Wed Feb 17, 2021 1:23 pm I had some cryoed Shuguang EL34 that sounded better than NOS RFT’s.
That's interesting Ali, I wonder if it works with 300b's.. or my be that why the are sounding better than those made 20 years ago, they do it as a matter of course.
Guess it would, though it’s equally possible I was conned on the NOS I suppose. They didn’t look used though. The Shuguangs I remember sounding very good.
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#143 Re: The Newton 300B

Post by steve s »

Ali, I sold a set of 4 telefunken el34s about 2 or 3 years ago at a radio rally, they looked like modern (1970s) far east production, in the same set there was a telefunken gz34, that was a re badged mullard.

I dont think telefunken actually made gz34 or el34's.. but they where available!
Last edited by steve s on Wed Feb 17, 2021 10:39 pm, edited 1 time in total.
The tube manual is quite like a telephone book. The number of it perfect. It is useful to make it possible to speak with a girl. But we can't see her beautiful face from the telephone number
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#144 Re: The Newton 300B

Post by steve s »

Nick wrote: Wed Feb 17, 2021 12:47 pm I think there is also an aspect that just being older means the structures of the valve have had longer to "relax" in the same way that cryo treatment seems to.
May well be right nick, but something like vt75/kt66, the pre war / wartime coke bottle valves sound so much better than the post war versions, the straight sided post war types would be getting better as they aged, but I've not heard one that sounds like the early version.


The vt 75s I have are a maximum 82 years old, the 'modern' kt66 I've compared then to would be 65- 75 years old. Not really much difference in age

There are differences in the anode shape too, but they are spec'd the same
The same goes for el37s the famous fatbottle version,
And most other valves of the era.
The tube manual is quite like a telephone book. The number of it perfect. It is useful to make it possible to speak with a girl. But we can't see her beautiful face from the telephone number
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#145 Re: The Newton 300B

Post by Ali Tait »

steve s wrote: Wed Feb 17, 2021 10:18 pm Ali, I sold a set of 4 telefunken el34s about 2 or 3 years ago at a radio rally, they looked like modern (1970s) far east production, in the same set there was a telefunken gz34, that was a re badged mullard.

I dont think telefunken actually made gz34 or el34's.. but they where available!
Never seen any either Steve, just rebadged then?
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#146 Re: The Newton 300B

Post by steve s »

Ali Tait wrote: Wed Feb 17, 2021 10:40 pm

Never seen any either Steve, just rebadged then?
That's my understanding Ali., thinking about the valves I had they also could have been made in east Germany
The tube manual is quite like a telephone book. The number of it perfect. It is useful to make it possible to speak with a girl. But we can't see her beautiful face from the telephone number
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#147 Re: The Newton 300B

Post by Nick »

Yep, I did say:
I think there is also an aspect
Not that it was the only aspect, I also think that design choices may well have changed pre and during war and after the war may not have returned to pre war designs as maybe they were cheaper and quicker to make and no one seemed to complain about any difference.
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#148 Re: The Newton 300B

Post by Ant »

Wonder wether it was to do with strategic materials?
Post war, stuff like steel, copper, tungsten, et cetera was in short supply, i remember reading somewhere that the reason the original land rover body was riveted aluminium because there simply wasnt the steel available to do it with.
Perhaps valve internals were made of different blends of materials for the alloys and cathode coatings, or less pure metals because of the relative scarcity?

The designs will have changed to make things squaddie proof, much faster to produce, and to use less stratgically important materials, (less copper in a valve structure or something means more available for making the wiring in an aircraft/tank ect) and easier to transport.
Imagine the amount of straight sided valves you could fit per box (for the use of) as opposed to the amount of st bottles in the same box
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#149 Final pictures

Post by Thermionic Idler »

I think I can sign this project off now, as the amps have been performing faultlessly since the last round of mods.

Some daylight pics of them in position, left and right channels

Image

Image

And because this is the internet...

Image
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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#150 Re: The Newton 300B

Post by Cressy Snr »

Great sound, superlative construction standards inside and out, and fabulous looks (and that’s just the cat.) What more could one want.
Enjoy them Dave. :D
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