I remember an article back in the 1980s with amplifier designers from various manufacturers being asked what they’d use if they couldn’t use their designs from the manufacturer they worked for. All of them answered they’d use something they’d built previously, except Julian Vereker who said he’d use a Quad valve system with Quad ESLs. I have front-ended my Quad II/22 system with a 272 and it acquitted itself very well for a 1950’s design but could not match the resolution of more modern gear and the phase response is such that stereo imaging is ok at some frequencies and indistinct at others. High frequency transients were generally what suffered in this regard and its down to the output transformers.
Hi Pete,
Historically I have used an EAR864 and 868 with CB250 to good effect.
Currently my Phono stage is a Tron 7 GT - superb.
M
That’s an interesting anecdote! ISTR other mentions of Quad in relation to Naim, in a positive way. Nice that on occasion manufacturers can hold each other in high regard.
I suspect there is a lot of mutual respect and in fact instances of “wow I wish we’d made that.” However, from a marketing and PR perspective, many such thoughts about contemporary gear have to be suppressed and self censored. You can’t have Naim engineers in interviews saying , “God I wish the SN3 sounded like the PMC Cor amp. What a machine!”
We only get stuff in long hindsight. Most engineers at many manufacturers probably have a lot of praise and admiration for other stuff they keep bottled up.
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I’ve read some very good reviews and user opinions on Decware valve amps. I’d love to try one at some point in a vinyl setup.
I’ve owned a number of tube amplifiers including an ARC SP9/Classic 30, Audio Space AS3i, Audiomat Arpege Reference and currently a Jadis I35. I ran a CD5 with the Audiomat which I found highly complementary and currently an nDac with the Jadis.
Like others I’m not at all fond of weight, and wasted energy and heat of a tube amp but those issues disappear for me the minute sound comes out of the Jadis!
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Sure many valve amps can have a warmish sound, but there are various reasons… but driving valves too hard, just like with semiconductors, results in clipping and the creation of harmonics that will artificially brighten a sound.
Sure there seem to be more stray capacitances associated with valves so the harmonics may be less with valve and so sound less harsh, perhaps even a lot less hard than with semiconductors…. But I can’t see how driving a valve hard or even misbiasing it can cause a warner (yet pleasant) sound.
Impedance (mis) matching certainly can as well as making a brighter or colder sound. You may find this can occur with different valve types.
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A lot of the warmth people mention comes from using valves in the rectification stage.
Compared to diode rectification, the residual 50/60Hz ripple on the DC output is quite pronounced. This distortion comes through downstream and some find mildly pleasant. Secondly, the size of capacitor that can follow directory after a rectifier tube is far smaller than what can be used after a diode. This also greatly affects the output in ways that I admit are a bit beyond my understanding but the lower value capacitor is said to find most of its workload within servicing current requests from the output stage for midrange (vocals, pianos etc.) and is not really sufficient for higher power transients at the frequency extremes which again leaves a warm midrange enhanced feeling.
@Simon-in-Suffolk There is driving tubes hard and driving too hard. From my limited experience, driving tubes within their load capacity sounds vastly different than driving well under capacity. In both cases clipping doesn’t occur. From reading about the design of my valve amp, the tubes used are common enough in other valve amps rated at much higher output in the 20-25w range but a decision was made to limit their use parameters to 10w to extend the life to match the caps and to avoid the amp sounding overly warm and make it a bit more balanced overall.
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I owned a pair of VTL 50w monoblocks for many years…they were punchy and open and surprisingly powerful. I put them in the loft for 12 years… bought my 272/250dr combo…I decided to sell the valve amps…which were now 30 years old on the orginal valves. I hooked them up to the 272…and omg…they were awesome…punchy dynamic…and open. They gave the 250dr a real run for their money. So if ever you get an opertunity give the VTL a listen…
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That’s the direction I’m heading.
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Warmth varies in the way @feeling_zen explained. It’s how far tubes are pushed within their operating range that will impart more or less warmth. It was explained to me as follows when I was enquiring about warm sounding tube amps compared to the ones that sound more neutral/transparent. Obviously there are other factors at play but how far tubes are pushed as plays a part.
"Tubes when operated gently but higher up their operating envelope will last longer instead of falling over abruptly.
The tonal balance of the amp can be set by how far the tubes are pushed in their operating range before they reach clipping (which will create distortion). Higher up their range they will saturate (making the sound warmer and fuller) and gradually begin producing second order harmonics (which sound like the musical octave) as they begin to distort.
With solid state amplifiers, the change from clean sounding music to the point it is distorted is more sudden and extreme by comparison. Digital can be even worse. While they do everything to stay clean for longer, when they do finally cross the threshold, the result is ugly sounding."
I play a Linn LP12 through an EAR Phonobox valve preamp into a UnitiStar and ProAc D20R.
Sound pretty good to me, although the purists tell me I need better amplification.
I’m more than happy with it.
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Bet it’s sounds great but I find that a little odd, vinly into a valve amp and then into a amp that turns everything into digital.
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Can’t explain the logic! Ears are the measuring tool.
Yes it sounds fab. LP 12 compared to the Star’s streaming is absolutely huge. Not warm, a perfect balance to my ear.
Since upgrading my entire system apart from the turntable, I was recommended the EAR and have not been disappointed.
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I can just see, in a few years, a nice smallish setup in a separate room with valve amp(s), my second speakers, and a Rega P8 or P10. And I suppose I would have to re-buy the Graham Slee Reflex M Phono stage I sold a few years back. Saw that one coming …
I’d leave the digital setup alone as it sounds great as is.
Maybe Decware has an Integrated valve amp with an on-board phono stage?
I hadn’t heard of that before - perhaps I will look into that.
That depends on the design to some extent - but yes like with most electronic components not driving them towards the top of their power envelope will help them last longer.
I find a key thing for longevity - is proper warm up time before you apply current to the device absolutely extends their life. One of my amps (an RF power amp) has an electronic timer before the amp kicks in to allow the power pentode to get appropriate operating temperature before switching to amplifier mode, and variable forced air flow when driven hard and optimally so as to avoid excessive heating (they generate a lot of heat when continuoulsy driving a 400W load) - which would otherwise shorten the pentode’s life. These high power RF power pentodes are large expensive devices - so it warrants this sort of protection. BTW I have never had an abrupt failure (possibly because of the care applied) - the odd failure I have had with power pentodes has caused extreme distortion and very non optimum current draw… but it has still operated - if you can call it that.
All my valve amps - both high power and low power - use semiconductor rectification.
I find in some of my other valve amps mixing pre stage pentode with driver power triode devices (what some call ‘tube rolling’ changes the warmth or brightness across all power settings. Setting the gain of the amp and matching for load impedance on a directly coupled class A can also affect bandwidth and warmth as well.
All good fun - I actually prefer my valve audio amps to be quite bright, and I tend to dislike obvious valve ‘warmth’ - its too coloured for me. On audio amps I tend to tube roll to get the sonic balance for a given load impedance I like.
Simon
Did someone mention valve based rectifiers?
Is not quite a valve based rectifier, but is a fun watch. If hair raising. Photoninduction testing a 50 yr old Mercury arc rectifier. In his front room. And you thought your latest floorstanders were a bit much!
Hopefully ok with forum rules, as I’m sure the chances of any members owning one, and thus being encouraged to crack open the box to test it, are small.
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Interesting. Still waiting on the arrival of my Tube Amp. It’s been a month or so since I demoed it at one of the few dealers handling them. I have a feeling it may still be quite a while before my build is finished.
It’s a Class A headphone amp with a solid state rectifier, 6SN7 drivers and 300b power tubes. From memory it’s not what I’d call neutral but it certainly doesn’t have that bass sag that’s often associated with tube amps. Clarity, bass extension + texture, dynamics, large sound stage with very clear layering are what really jumped out at me. I Should be interesting.
Brilliant and nuts. I’ll keep an eye for his name in the obituaries section.
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