Bonky
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Posts: 156
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Post by Bonky on Feb 11, 2018 14:31:39 GMT
Hi, I'm still contemplating a valve amp but wonder if there are likely to be any more developments in their design. I have the feeling 'no', (or very small incremental changes). I put this down (in my naive way) to the relative simplicity of designs and that valves/tubes are old technology. Again, excuse my naivety, but I believe the same isn't quite true of SS amps - although they too must soon be struggling to find any new/original/breath-taking break-throughs, (apart from 'audiophile fuses ' etc!)
Am I wrong?
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Deleted
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Post by Deleted on Feb 11, 2018 14:41:14 GMT
Happy Birthday, bonky.
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Bonky
Rank: Trio
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Post by Bonky on Feb 11, 2018 14:42:10 GMT
That's very kind...thank you!
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Post by Deleted on Feb 11, 2018 14:51:35 GMT
I think most valve amps are reworkings of very old designs. Likely they peaked years ago. Only difference is in most cases component reliability is better.
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Post by dsjr on Feb 11, 2018 15:09:21 GMT
I'd politely suggest that valve amps peaked decades ago (50's and 60's?) and the best of today's may well be re-workings of old classic designs. I believe E.A.R. may have custom transformers made to Tim's particular spec (he's one of a handful who probably could re-design a valve circuit and probably has a few times over the years) and of course, Tim for one, designed the 509 and 519 around TV output valves - his argument was that if a valve like this could run 15K flat out for many years then as an audio valve it would be barely coasting, and I believe he was proved right...
I think the main issue here isn't with the valves as such (although the fact you can tube-roll and general short lifespans indicate something's still not right here), but with the output transformers which add all manner of nasties to most valve output stages unless they're very carefully designed and probably expensive overkill for the amp they're partnered with. Look at the Stereophile Prima-Luna reviews to see how it *shouldn't* be done - rollercoaster response into a real speaker and ringing at 40 to 50kHz... I believe it was a Quicksilver design (can't be arsed to look - sorry) which hardly affected the response into speaker loads at all and it *sounded* very good too...
Does anyone here remember the company (Tech-Tube) that nearly came out of the ashes of the Mullard-Philips CRT factory? The last generations of CRT TV tubes seemed to be very long lasting indeed and the business end was found to be adaptable to audio use. they launched some popular small-signal valves based on the then mature CRT technology but the financial backers pulled the plug after a year or so (even less, I can't remember) and the company and the bright ideas they nurtured disappeared.
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Post by Deleted on Feb 11, 2018 16:02:01 GMT
I'd agree that valve amps peaked decades ago, but the same can be said for Solid State. Today's offerings are usually just re-hashes of old circuits.
Edit: Class D/T excluded, but I would never consider mentioning them in the same sentence as "zenith". Nadir, maybe.
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Post by Clive on Feb 11, 2018 16:20:56 GMT
Some of the Rozenblit diy OTL designs are using better optimisations than OTLs of yore.
My Black Tulip SS power amp hails from the 80s but is as modern as many sophisticated Class AB amps so not much progress there.
Maybe with SS the transistors used have moved on from what was available in the 70s but are they noticeably better or just different?
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Post by dsjr on Feb 11, 2018 16:39:23 GMT
I'd agree that valve amps peaked decades ago, but the same can be said for Solid State. Today's offerings are usually just re-hashes of old circuits. Edit: Class D/T excluded, but I would never consider mentioning them in the same sentence as "zenith". Nadir, maybe. I'm no engineer (couldn't do the maths needed), but as I understand it, although solid state topology may not have changed too much in the basic sense, the devices used did develop hugely over the years and may still be evolving. I'm sure his growing experience in the audio field may have contributed to this, but the 'versions' of AVI amps that Martin Grindrod designed in the 90's were developed to take advantage of new devices coming to market and his last old-school model was the huge but low slung S2000A power amp at 200WPC or so. Where a typical 90's US amp had a multitude of output transistors all trying to match each other for minimal distortion, it became possible to do the same job with just two per channel and certainly no more than four for a 140W amp. Maybe I have it totally wrong (apologies of so), but looking at some amps I've owned with a dozen output transistors per channel (in series/parallel?) scared the sh*t out of me.
One amp I should have persevered with was a Croft OTL, this one unregulated* and having the simplest circuit I'd ever seen, apart from the quad of output valves per channel. This was Glenn's last unregulated one and it kept blowing line fuses with no warning and even idling quietly one Saturday evening with friends round, I had an internal firework display from it - it was checked over and sold pronto.
*Glenn developed a regulated supply circuit for his OTL's and I should have paid to have mine updated should it have been possible. When it worked and into 'easy' speakers, it sounded amazing, but then, the replacement AVI amps (via a freshly updated Quad 405-2) sounded as good musically and far better in 'HiFi' aspects and of course, they ran stone cold and NEVER ONCE caused reliability concerns...
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Post by Deleted on Feb 11, 2018 19:52:45 GMT
Sadly I've still never heard an OTL amp. Fate has also conspired several times to rob me of a chance to own Croft amps. My last attempt was aborted via mutual agreement with the seller after the courier returned them to him twice without actually attempting a delivery to me! They were a real bargain too! Never mind, I'm really happy with what I have and I'm more into the build and aesthetics than the sound these days.
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Post by Chris on Feb 11, 2018 22:34:27 GMT
I'm kind of the opinion that valves are moving on a bit. We've seen things like KT120s and KT150s emerge so whilst certain circuits will always be used these newer valves may very well inspire something different. Internal components are getting better and better as well.
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Post by MartinT on Feb 12, 2018 3:51:26 GMT
In the same way as new valves have emerged, there are high frequency power MOSFETs on the market now which do a fine job in solid state designs. Topology is more important and the previously mentioned Tim de Paravicini has created some excellent designs. I used to have one of his phono stages and it always fascinated me that he's not a believer in special valves or components.
It's just a preference and there are good and poor designs using both valves and transistors out there.
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Post by steveeb on Feb 12, 2018 9:51:13 GMT
Much as many won't like the idea that streaming can become a credible rival source to vinyl, significant amplifier development seems to be in Class D.
Read about the SPEC company, lifelong advocates of SET valve amps, now claiming (and arguably succeeding) in achieving 'better' results with Class D and a flagship model at £14k. Or Technics return to the home audio scene with not dissimilar technical innovation to minimise the signal corruption at £63k, Class D.
New GaN FETs are a tangible tool for designers to address some basic issues with the technology, plus digital volume control and back EMF management.
I was also interested to see Technics use of wideband drivers in their speakers.
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Post by MartinT on Feb 12, 2018 11:24:39 GMT
Mark Levinson also have some high end class D amps.
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Post by daytona600 on Feb 12, 2018 11:53:24 GMT
nothing new in audio for decades heard a 1920s full western electric rig a few years ago & shamed most modern gear
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Post by dsjr on Feb 12, 2018 14:15:12 GMT
In the same way as new valves have emerged, there are high frequency power MOSFETs on the market now which do a fine job in solid state designs. Topology is more important and the previously mentioned Tim de Paravicini has created some excellent designs. I used to have one of his phono stages and it always fascinated me that he's not a believer in special valves or components. It's just a preference and there are good and poor designs using both valves and transistors out there. As long as these MOS-FETS match each other better than older ones did (I'm told that one 'side' of a pair never properly matched the other as conventional transistors do). Nick Gorham (Longdog Audio) is apparently using or researching something very interesting in his new amps, but I know little more. Apparently his phono stages despite the cost, are supremely good in all the important musical areas... Maybe another maker for Martin to investigate seriously as they look the part too...
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Post by Deleted on Feb 12, 2018 15:06:14 GMT
They say MOS FETS have a "sound" but I've never understood what that was. I've had a few over the years but not found any common ground. My little TMA3 uses them, as have some MF I've owned but there was no common thread. I think the Claymore used them too. I still love the look of the Claymore and I deeply regret not buying that blue one at the Sound Org. I later had a Claymore 2 but it didn't do anything for me (sorry Colin). If it had looked like the original model, I wouldn't have cared: I'd have loved it for its design. Sorry, I'm rambling
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Post by MartinT on Feb 12, 2018 15:15:47 GMT
Apparently his phono stages despite the cost, are supremely good in all the important musical areas... Maybe another maker for Martin to investigate seriously as they look the part too... I did evaluate the Longdog phono stage and it was excellent. I ended up buying an Aurorasound VIDA only because it was marginally better sounding still.
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Post by daytona600 on Feb 12, 2018 16:02:13 GMT
As long as these MOS-FETS match each other better than older ones did (I'm told that one 'side' of a pair never properly matched the other as conventional transistors do). Nick Gorham (Longdog Audio) is apparently using or researching something very interesting in his new amps, but I know little more. Nick uses different mosfets in pairs from same supplier Ixys in germany power mosfets generally used in industrial high power switching applications , inverter drives , welders in audio applications watts not kilowatts they are " ticking over " & his recent monoblocks vsounded nice indeed , balanced , dynamic & punchy
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Post by Deleted on Feb 12, 2018 16:07:56 GMT
Apparently his phono stages despite the cost, are supremely good in all the important musical areas... Maybe another maker for Martin to investigate seriously as they look the part too... I did evaluate the Longdog phono stage and it was excellent. I ended up buying an Aurorasound VIDA only because it was marginally better sounding still Have you tried the Ayre P5 XE Martin? I ask because it looks like I'm getting back into vinyl in spades and I've been offered one. It's probably overkill as far as I'm concerned but the price is keen, so I thought it worth asking.
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Post by MartinT on Feb 12, 2018 18:57:41 GMT
No Andrew, I've never even seen one in this country. There are also the Pass XP phono stages which have a great reputation. I must admit that my future investment in vinyl equipment is likely to be zero, I'm happy with what I have and prefer now to squeeze every last drop of performance from digital.
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