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I have always been curious what these tube emulators were doing and finally took a peak. Here is what I found.
This tube emulator has 8 presets emulating different tube gear and is used in production track mixing. I thought it might be interesting to optionally add a "tube buffer" into the chain for a quick A/B.
I installed the VST plugin to JRMC, measured without (baseline = red bottom plot) and with each of the 8 preset configurations.
From the measurements, they add 2nd order harmonic distortion in varying amounts up to an additional 25dB depending on the profile selected as seen in the plot below.
They also play with the EQ profiles, volume and slightly shift phase by up to 60 degrees.
Here is another plot using the Harmonic Frequency as a reference and hiding harmonics below the noise floor. As you can see, most of the baseline is below the noise floor with the emulations clearly above the noise floor.
The notion that tubes "add" something to the signal is NOT what good tube products offer; it is in fact the exact opposite: it is what they DON'T add (but solid state does) that makes them (some think) superior to ss. Greater low-level linearity, less odd-order harmonic distortion, greater depth of field, more lifelike reproduction of instrumental timbre and tonal "density", more 3-dimensional images, "soft" amplifier clipping, greater headroom, lack of "grain", higher resolution and transparency, etc.
Of course the above are crude generalizations: superior solid state beats mediocre tube. Tim de Paravicini offers both tube and solid state products in his EAR-Yoshino line of electronics, using whichever he feels better for a given job. He offers a great solid state RIAA phono amp, but most of his products employ tubes for amplification. The electronics in the analog recorder and condenser microphones Kav Alexander uses to create his Grammy Award winning recordings (Water Lily Records) were designed and built by Tim. Tim was also involved in the Pink Floyd Studio in London.
I haven't had much experience with tubes, real or otherwise... :)
Take this with the appropriate grains of salt, but my singular experience in the context of my own system was replacing a Pass X350 with a VAC Phi 300.1 and my initial impression was that it sounded amazingly similar. Over time, I teased out subtle subjective differences, but I was not blind to which amp was which and one could say that I had a vested interest in preferring the amp for which I had most recently shelled out 5 figures.
So, I think it probably has less to do with tubes vs transistors and more to do with design and execution, not to mention synergy with the load presented by the speakers. I have no regrets about purchasing that valve amp and I'm sure it was the finest piece of HiFi gear I will ever own, but I can't say that I really miss it either. The experience satisfied a yearning and a curiosity, which translated into more satisfaction with the solid state amps.
Seriously appreciate the candid comments! Not that I'm in a position to buy a 5 figure amp. 😁
Grant, if and when you want to try a tube amp with your Maggies, there is one that is unusually apropos for that application: the Music Reference RM-200. It was designed and built by tube expert Roger Modjeski, who wanted to have a tube design that offers a few unique features:
1- The RM-200 has a solid state input stage, tube driver and output stages.
2- The amp has loudspeaker impedance taps (solid brass binding posts) of 1ohm, 2ohms, 4ohms, and 8 ohms.
3- It is very unique for a tube design in that it's power output into a 4ohm load is the same as into an 8ohm one: 100 watts RMS. All other tube amps (other than OTL's) produce considerably less power into a 4ohm load than into an 8, typically 60 watts at 4 vs. 100 at 8.
4- RM achieves 100 watts with only a single pair of KT88's (per channel), and does so without the cost of shortened tube life (modest tube dissipation).
5- The amp is balanced, it's inputs on XLR jacks only (input impedance 30k ohms).
6- The amp was produced (Modjeski passed away last year, so no more will be produced) in two basic versions: the original, and the slightly improved Mk.2. Their price on the used market is approximately $2000 for the original and $3000 for the MK.2. They don't appear often, so be prepared to pounce when you see one!
7- Both versions have been reviewed by Michael Fremer in Stereophile, and ranked in the Class A category. The sound quality and character of the amp is perfect for Maggies; not the soft high frequencies and mushy bass of lesser tube amps, and none of the somewhat dry, hard, or "etched" highs found in many solid state amps, a characteristic easily revealed by the Maggie ribbon tweeter. Liquidly transparent, excellent low level resolution, great depth and sound-staging, a champ at reproducing the organic timbre of acoustic instruments and vocals. An all-around excellent amp, and at a reasonable price.
100 watts may appear to be barely adequate for Maggies, but tube watts are different than ss watts. The RM-200 should be enough for 3 series Maggies in average-size rooms, especially if the speakers are used with a sub or two and a high-pass x/o filtering the signal going to the amp.
Back in the day, when there was a great interest in this matter I was present as a bystander (in Lyric Hi-Fi) during a shoot-out between a ARC D79 (tubed) and a Mark Levinson (SS) amplifer. Differences in their sound, 'nada'. Listeners included Mike Kay and one of his potential customers who was ready to buy one or the other.
Many years back I did try a Mobile Fidelity tube buffer (if I recall the part description properly). In my system, to my ears... I did not like what I heard.
What almost always jumps to mind in such discussions is that three Stereophile editors were unable to hear *any* differences (using selected program material and loudspeakers) when comparing a tubed to solid state amplifier.
('Carver Stereophile Challenge')
But that was from Bob Carver purposely manipulating a solid state amp in a very sophisticated way to sound exactly like the tube amp used in the challenge. It wasn't meant to prove there is no no sonic differences between tube and solid state amps. Rather that he could make a solid state amp sound like anything he wanted it too.
Exactly. It wasn't a case of SS vs, tubes, BC's tweaked mid-fi SS amp's sound just happened (?) was made to imitate the sound of a tube amp, costing nearly ten times more (and without its heat).
It was presumed he also could have tweaked his mid-fi product to imitate the sound of a much more costly SS Mark Levinson amp.
".... I would love for BC to produce some genuine red-blooded tube amplifier replicas. It will accelerate the growth of NYAL because it would increase the public's awareness of the unique virtues of tubes. ...." Harvey Rosenberg, NYAL.
However, then it would no longer be *UNIQUE* to tubes.
Thanks for posting the link.
The tube/Levinson amp emulations is news to me.
As technology progresses, I wouldn't doubt the sound of any piece of gear could be emulated through DSP providing the base gear is clean enough to serve as the foundation for the DSP to be layered on top of. Bad news for HW manufacturers.
That is pretty much what I recall, but that was a read from quite some time ago...
When Stereophile first published the article they didn't disclose what the target amplifier was. They didn't publish that until years later. Pretty amazing that Bob Carver was able to pull that off. I wish I could afford one of his current tube amps. Interesting that that's all he makes now.
Do either of you have a link to the story/article/shootout ?
I have only heard tubes at dealers and a tube radio and tube TV when I was very young so I can't really say if the emulator sounded the same or not.
I would have to spend more time running through the options without the EQ profiles being changed. The 8 presets also tip up/down the high and low ends and also boost SPL.
We know increased SPL is perceived as "better", so those frequency/volume changes mask the even order distortion signatures.
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