Why Don't People Muse About Tube Amps That Have The Tone and Timbre of Solid State?

[MylesBAstor]

I guess it’s time to come out of the SS closet. I have been using tube gear exclusively since around 1985 (preamps and power amps) and was using tube preamps exclusively for several years before that. So basically for the last 27 years I have been listening to tubes in my system. That’s over a quarter century of tube listening. During that time I had convinced myself of the superiority of tubes and would basically turn my nose up at the sight of SS gear.

And then something snapped, and it snapped a few times before it finally broke. And the catalyst for the ‘snap’ was a combination of a very low ambient noise level in my listening room coupled with the noise of tube phono stages, tube preamps, and tube power amps mixed in with the inherent problems of output tubes being eaten and small signal tubes going noisy or should I say nosier and along for the ride, their first cousin named ‘Microphonic.’ They all combined together for a potent toxic mix.

One of the times it ‘snapped’ was when my ARV VT-100 MKII started acting squirrely and making a strange low frequency oscillation sound that I thought was going to take out my subs and possibly the sub amps. I was going to go ahead and buy new tubes and set the bias until I read the bias procedure and saw it was straight out of Chapter 1 of Dante’s Inferno. There is a reason Uncle Kevin from Upscale Audio refuses to sell tubes for any VT-100 series amp.

Before I owned the VT-100 MKII amp I had stuck my toes in SS waters when I purchased a Pass Labs X-250 amp. The X-250 was a disaster in my system. It sounded more like a 25 watt amp. I was glad to get back to tubes when I bought the ARC VT-100 MKII. Next up to bat was the Jadis Defy 7 MKII which I found the looks striking and the midrange glorious. It also gloriously munched on my 6550 output tubes and every time it eats a 6550, it takes out the cathode fuse and sometimes the cathode resistor. I could go on and on about the nonsense you have to put up with if you own a Defy 7 (and I have talked about the nonsense in the past).

Sometime before my last Defy 7 problem I had taken my Teac R2R to a local repair shop. While I was in there I eyeballed a Phase Linear 400 Series 2 amp. The owner explained that he had completely gone through it, replaced the power supply caps with higher value caps, and it was working perfectly. I bought it as a backup knowing that with tube amps, you need a backup. So when the Jadis munched another 6550 and took out a cathode resistor with it and I was waiting for Brooks Berdan to ship me a replacement resistor, I installed the Phase Linear amp in my system.

So now I’m a little shocked at what I’m hearing and not hearing. There is a quality to the bass reproduction from 20 Hz to 160 Hz (the bottom three octaves) that tube amps can dream about, but can never really achieve. Let’s face reality: tube amps struggle with both accurate bass and accurate high frequencies. It’s the nature of the beast when dealing with tubes and output transformers. Tubes are inherently high impedance/low current devices. Output transformers help convert the high impedance and low current to a lower impedance and higher current, but it still doesn’t come close to what a SS output stage can do.

Added in with the low current that output tubes have is the low dampening factor. Even though some tube companies (think ARC) try to compensate for this by building massive capacitor banks for energy storage, they still can’t get around the low dampening factor. A tube amp is never going to have the iron fisted control over your woofers that SS has.

High frequencies bring on another set of issues with tube amps. Because the output impedance of a tube amp is so high, there is always an interaction between the changing impedance of the loudspeaker across the frequency bandwidth and how that affects the highs. We can all kid ourselves and say it doesn’t really matter and the highs sound just fine. I know I did for over 25 years. But when you seriously listen to a great SS amp and you still want to cling to that line, you have crossed over into the land of make-believe.

And what about that glorious tube midrange? The midrange of tube amps is about the only thing they come close to getting right because they can’t get the bass or high frequencies right for reasons I stated above. And we hear all types of adjectives used to describe the glories of tube midrange, but I seriously think that any harmonics you hear through a tube amp in the midrange that you find lacking in a great SS amp are just low levels of harmonic distortion being added to the signal that is pleasing to the ear. You can come up with your own counter-theories like “Oh no, tube amps are just letting you hear the harmonics that SS strips out from the signal. Uh-huh. The only difference between that statement and a fairy tale is that it didn’t start off by saying “Once upon a time…”

As for tube phono sections and tube line stages, don’t even get me started. Here is where the low transconductance of tubes becomes their own worst enemy with regards to noise. If you want the absolute lowest noise you can achieve in your system and thereby increase the purity of the signal by eliminating distortions, you aren’t going to get there with tubes. Tube phono stages and line stages will add noise to your signal that will ride right along all the way to the power amp. And if you are using a pure tube preamp to amplify low output MC cartridges, you are adding lots of noise that is being amplified by both the line stage and power amp.

I had over $5K invested in my pure tube Counterpoint SA-5.1 preamp with all of the upgrades and it wasn’t all that long ago that I thought it was the bomb. While it was off for its last round of upgrades I bought a Yamaha C2a to tide me over. I have written all of this before. I was embarrassed how badly the C2a bettered my Counterpoint.

Fast forward to the near present: While my Krell KSA-250 was back at the factory for what I thought was going to be a repair and shipment off to its new owner, I decided to buy yet another tube amp and tube preamp. I bought the ARC VS-115 and the ARC LS-17. I have written a mini-review of the VS-115 and the LS-17. The VS115 is the best sounding tube amp I have ever owned. It has the best tube bass I have ever heard. But it’s certainly not the best amp I have owned or even close to the best bass that I have heard. The LS-17 was the second one that I have owned and it sounded just as bad as the first one I owned. But the bottom line is that the VS115 is not capable of the performance of a great SS amp in my experience. And I hate to say this, but it’s not even capable of the performance of a really good SS amp.

I am officially done with the ‘glories’ of tube preamps and power amps. If the highest fidelity to the source is truly your goal, you are not going to get there with tubes. You will be adding measurable amounts of distortion and noise to your signal at every step of your tube chain. It’s time to put the VS115 up for sale so it can find a new owner who can revel in the tube magic and glory. For once and for all, I think I have finally broken my addiction to vacuum tubes. Out of all the adjectives you can use to describe the magical tube sound, the one adjective that doesn’t apply is ‘accurate.’ Like I said in a thread I started some time back, it really is all a preference.

Except for most of cherished recordings were recorded with tube electronics.

You're welcome to hear the new cj electronics, Doshi phono and let me know if you feel the same way.

 

[ack]

I am officially done with the ‘glories’ of tube preamps and power amps. If the highest fidelity to the source is truly your goal, you are not going to get there with tubes. You will be adding measurable amounts of distortion and noise to your signal at every step of your tube chain. [...]Out of all the adjectives you can use to describe the magical tube sound, the one adjective that doesn’t apply is ‘accurate.’

Exceptional post overall, Mark, and am in complete agreement... with a couple of exceptions. Try VTL or Lamm amplification as appropriate with your speakers, one last time, before you sign off from tubeland. Frankly, there is much better tube gear than Counterpoint and Audio Research, and you may have just limited yourself in that respect.

 

[slowGEEZR]

Thanks for the clarification mep! I too, would not be too worried about whether the stereo survived that! It's funny, many years ago I maintained the communication gear in some Minute Man missile underground control capsules. One of the more interesting types of communication gear was a super low frequency radio (SLFCS) which was there specifically to communicate after a nuclear attack.

 

[cjfrbw]

Every time I have tried to wean myself from tubes, it was like slow acting pernicious anemia. Everything seemed fine at first, or so I convinced myself, as the vitality seemed to drain by degrees from the listening experience over days, months.

Tubes back, voila.

I am not anti transistor, I am listening to some right now and it sounds great, but mainly as a diversion from the main course.

 

[cjfrbw]

What Carver did -- I assume you're talking about The Carver Challenge -- was not nearly that simple. You've been there, done that? You've heard that Carver amp and compared it to the tube amp it emulated?

Tim

Not what I said. Sorry, won't do the straw man tango, but I am sure there are others on your dance card.

 

[Gregadd]

Myles and Mep I recall J.Gordon Holt having a chronic love /hate relationship with tubes and solid state. It''ll pass.

 

[mep]

Exceptional post overall, Mark, and am in complete agreement... with a couple of exceptions. Try VTL or Lamm amplification as appropriate with your speakers, one last time, before you sign off from tubeland. Frankly, there is much better tube gear than Counterpoint and Audio Research, and you may have just limited yourself in that respect.

I did have the pleasure of having a pair of VTL MB-100 amps in my system for a few weeks thanks to a friend of mine and I can tell you they sounded very nice. They had a very pleasant sound that was appealing. And it was appealing in the much the way the pair of Quicksilver V4s I owned were also appealing. Every recording I played through them seemed to have the same amount of ‘goodness’ which I know isn’t right. All recordings sound different one from another, but both the VTL MB100s and the Quicksilver V4s somehow homogenized the sound down to a pleasant sounding common denominator. Something the Quicksilver MS-190 with the triode input boards never did.

 

[ack]

I did have the pleasure of having a pair of VTL MB-100 amps in my system for a few weeks thanks to a friend of mine and I can tell you they sounded very nice. They had a very pleasant sound that was appealing. And it was appealing in the much the way the pair of Quicksilver V4s I owned were also appealing. Every recording I played through them seemed to have the same amount of ‘goodness’ which I know isn’t right. All recordings sound different one from another, but both the VTL MB100s and the Quicksilver V4s somehow homogenized the sound down to a pleasant sounding common denominator. Something the Quicksilver MS-190 with the triode input boards never did.

Curious... why didn't you go the VTL direction then?

 

[MylesBAstor]

Every time I have tried to wean myself from tubes, it was like slow acting pernicious anemia. Everything seemed fine at first, or so I convinced myself, as the vitality seemed to drain by degrees from the listening experience over days, months.

Tubes back, voila.

I am not anti transistor, I am listening to some right now and it sounds great, but mainly as a diversion from the main course.

Wow Carl, that post is like you are channelling old Mark

 

[cjfrbw]

Wow Carl, that post is like you are channelling old Mark

I know, and the "new Mark" sounds like the "old Phelonius". Will wonders never cease?

 

[MylesBAstor]

I know, and the "new Mark" sounds like the "old Phelonius". Will wonders never cease?

You know they say there's nothing worse than reformed smokers

 

[DonH50]

Some interesting points Don. Regarding your first point, I think it depends on which type of transistor is used for the distortion type. The distortion characteristics of MOSFETs are very similar to a tube's, while a bipolar transistor's is not. Also, if you are in the correct operating range of a transistor, you can have vanishingly low distortion. Many manufacturers of transistor gear push their transistors a little much, IMO and then try to correct the distortion with feedback. In my Pass Labs XA 100.5 amp, forty output transistors are used to put out 100 watts! Many transistor amp designers put out that much power just using four transistors. The distortion is very low when designed to be run in their ideal operating range! So, a tube can have lower distortion than a transistor, but not necessarily.

Regarding the radiation point, I plead ignorance. I've never been aware of any radiation problems with amps.

Regarding amp headroom. I had always thought that tube amps of the same power rating as transistor amps had more headroom. That was until I tried the NAGRA 60 watt transistor amp and the Ear 890 70 watt tube amp in my system. The little Nagra really seemed to have the edge over the Ear with my speakers, re: headroom. It could play louder without showing signs of stress at the volume levels the Ear started showing stress. That changed my mind and I came to realize that it was a function of amp design, not necessarily tube vs transistor. What really brought it home to me was how much more powerful the 100 watt Pass amp seemed vs my 100 watt tube amp.

I was speaking of the device theory, not the practice. Of course the biasing point and many other factors about the design influence what comes out the terminals. An ideal MOSFET has only second-order distortion and the series ends there so technically it's the winner. Unfortunately, ideal devices are hard to come by, so all the other terms creep in as well... And, MOSFETs have their own set of problems, including thermal runaway when biased heavily (ideally they weren't supposed to, but they did, and a lot of designers went back to the drawing board after their amps blew up). Bipolars have that problem too.

The radiation comment referred to surviving in a radiation environment, as mep said. A joke, a poor one, obviously. Actually, not just EMP, but radiation detectors and sensors in atomic energy research, etc.

Headroom, I was thinking more of preamps. Tubes offer gobs of voltage range compared to most transistor circuits. Headroom in a power amp is a very slippery concept, especially when comparing different architectures. Tube amps tend to clip "softer" but as you stated it is as much design (the way they are used in the circuits) as intrinsic device behavior. SS amps tend to "fall off a cliff" so their distortion rises rapidly when overdriven, while tube amps rise more gradually. Over most of their power range, a typical SS amp will have much lower distortion, and much much higher damping factor (lower output impedance), than a typical tube amp. I am sure we'll be bombarded by exceptions... However, this is again by design more so than device characteristics, though arguably the designers are picking topologies that emphasize the device characteristics they (and their customers) want to hear.

Aside: The input stage of most tube preamps is not designed to eliminate Miller capacitance, meaning they present a much higher input capacitance than many SS inputs. This came into play with phono inputs, where the extra capacitance rolled off the high end and made many a cartridge and record sound "smoother" and "sweeter" to the listener.

Aside II: Headroom in most power amps is a function of power supply capacity as well as output devices and bias, leading to large "dynamic headroom" claims for many amps. An amp with a "stiff" supply won't have much headroom over its spec, but will deliver twice the power into half the load ("double down") where a lesser amp will be derated at lower load impedance. Which sounds better is highly dependent upon the speakers and the listener.

On the Carver challenge, there were many similar trials, but his was most publicized. I did not hear his (in)famous "coffee-can" amp but did hear protos of the pre-production version when he brought one into the store I worked. I was able to compare it to the CJ amp of the day (I forget which one, the big monoblocks) and while not identical, to my ears and those who heard them, they were very close.

FWIWFM - Don

p.s. I by no means claim to be any sort of authority on amp design, just something I have piddled with on the side through the years.

 

[mep]

Curious... why didn't you go the VTL direction then?

I tried to explain in my above post that the VTL was very pleasant sounding like the Quicksilver V4s, but I'm not looking for components that homogenize the sound of all recordings so they have the same level of 'goodness' with regards to sound quality.

 

[mep]

Wow Carl, that post is like you are channelling old Mark

I had that coming and I'm sure some more too. As soon as I finished writing my post, I went through my dresser drawers looking for my asbestos undies.

 

[Phelonious Ponk]

Not what I said. Sorry, won't do the straw man tango, but I am sure there are others on your dance card.

\

Originally Posted by DonH50
Just add some even-order harmonics and kill the damping factor and you're mostly there...
a la Carver?

Been there, done that, no go, it is not the same. It would be nice if it were that simple.

[/QUOTE]
Perhaps I misunderstood you, but strawman? Nah.

Tim

 

[Phelonious Ponk]

I had that coming and I'm sure some more too. As soon as I finished writing my post, I went through my dresser drawers looking for my asbestos undies.

You don't need any shielding, Mark. You've put in a lot of time, work, frustration and funds. Let's just hope you've landed in a place you can settle into for a long, long time.

Tim

 

[mep]

You know they say there's nothing worse than reformed smokers

That sentiment is quite apropos. I get it, trust me. The good news is that I’m not one of those audiophiles that come to your house to hear your system and then proceed to slash and burn the quality of your gear and setup. I don’t believe in that. I have met far too many of these types of audiophiles over the years. If you don’t own what they own, what you have is junk.

I’m not going to forget what I loved about tubes for over 27 years. I’m just no longer going to turn a blind eye to what they can’t do which is why I made the change.

 

[MylesBAstor]

I had that coming and I'm sure some more too. As soon as I finished writing my post, I went through my dresser drawers looking for my asbestos undies.

Oh I knew you would take it as good natured ribbing

 

[slowGEEZR]

I was speaking of the device theory, not the practice. Of course the biasing point and many other factors about the design influence what comes out the terminals. An ideal MOSFET has only second-order distortion and the series ends there so technically it's the winner. Unfortunately, ideal devices are hard to come by, so all the other terms creep in as well... And, MOSFETs have their own set of problems, including thermal runaway when biased heavily (ideally they weren't supposed to, but they did, and a lot of designers went back to the drawing board after their amps blew up). Bipolars have that problem too.

The radiation comment referred to surviving in a radiation environment, as mep said. A joke, a poor one, obviously. Actually, not just EMP, but radiation detectors and sensors in atomic energy research, etc.

Headroom, I was thinking more of preamps. Tubes offer gobs of voltage range compared to most transistor circuits. Headroom in a power amp is a very slippery concept, especially when comparing different architectures. Tube amps tend to clip "softer" but as you stated it is as much design (the way they are used in the circuits) as intrinsic device behavior. SS amps tend to "fall off a cliff" so their distortion rises rapidly when overdriven, while tube amps rise more gradually. Over most of their power range, a typical SS amp will have much lower distortion, and much much higher damping factor (lower output impedance), than a typical tube amp. I am sure we'll be bombarded by exceptions... However, this is again by design more so than device characteristics, though arguably the designers are picking topologies that emphasize the device characteristics they (and their customers) want to hear.

Aside: The input stage of most tube preamps is not designed to eliminate Miller capacitance, meaning they present a much higher input capacitance than many SS inputs. This came into play with phono inputs, where the extra capacitance rolled off the high end and made many a cartridge and record sound "smoother" and "sweeter" to the listener.

Aside II: Headroom in most power amps is a function of power supply capacity as well as output devices and bias, leading to large "dynamic headroom" claims for many amps. An amp with a "stiff" supply won't have much headroom over its spec, but will deliver twice the power into half the load ("double down") where a lesser amp will be derated at lower load impedance. Which sounds better is highly dependent upon the speakers and the listener.

On the Carver challenge, there were many similar trials, but his was most publicized. I did not hear his (in)famous "coffee-can" amp but did hear protos of the pre-production version when he brought one into the store I worked. I was able to compare it to the CJ amp of the day (I forget which one, the big monoblocks) and while not identical, to my ears and those who heard them, they were very close.

FWIWFM - Don

p.s. I by no means claim to be any sort of authority on amp design, just something I have piddled with on the side through the years.

Ha ha, I'm by no means any sort of authority either, but it is fun to discuss sometimes.