Stereophile - MF Supercharger article-add 550W/ch.

Have you read this article in september issue of Stereophile?
It says that Supercharger pumps up your system to 550W/ch. and leaves "no sonic signature" - "Like a chameleon".

It works like this - simply connect Supercharger between your power (or integrated) amp and speakers.You only need a new set of very short speaker cables.You get 550 W/ch.,better dynamics and bass, and everything else is the same.
It is claimed that it only increases dynamics, and doesn't change "the sound" of your original amplifier.

Without questioning Stereophile's knowledge (it is my favorite magazine) i just find it hard to believe this.
My question - has anyone actually tried adding supercharger to the SET based system,2-20 Watts of primary amp. power?
And can any owner of such SET system say it didn't damage (a bit at least) the magic and "the sound" of SET tubes?
I am aware that in article Scott 299B(18 W/ch.) amp was connected with Supercharger.
I want to hear from owners of SET based systems who have tried this.Or from other people who have some opinion on this subject.I just find this hard to believe.
I read it and found it to be a very interesting concept. I would love to experience it myself. In theory, it should be no different than an amp passing on the "sound" of the source so I suppose as long as transparency is excellent, this amp should be able to do the same.

What they are doing is an old Carver trick.

If you remember the original Carver Cube amplifier ads they were selling a connection box which you connected your speaker cables to and then it converted the output into a low voltage connection bridge for their amplifier.

Your amplifier's output is restricted think putting a big resistor in line and all you get is a trickle of voltage.

This is a slick marketing gimmick, the intelligent thing would be to put in one of their amplifiers and be done with it.
I am not an expert on the topic, but i can't understand how pushing the signal through the transistor - based amps doesn't have any effect on quality and color of the sound.

I mean, it must leave SOME signature, right?These are SS amps, in push-pull mode, of course.
I don't argue on improvement in dynamics, that seems logical.

The whole point of this concept was to keep the sound you have and add power, bass and dynamics.Using them alone probably wasn't the main idea of MF.

But if what they are claiming is true - then you have ultimate sound!Use a 300B SET amp of 10 W/ch (or PX25 6W/ch), add Supercharger and that't the best ever imaginable system.

But i find this really hard to believe.
I agree with Audiobb. Merely putting in a passive volume control will change the sound of a system. I could buy the idea that the sonic change is minimal compared to the increase in dynamics and bass, which could overwhelm any change in tonal balance, detail, etc. It is an old but interesting idea. I loved the sound that some 15wpc Cary Audio 300B SET amps made with my Watt Puppy 7's--voices and instruments had a ton of presence, but I couldn't accept the floppy bass and reduced dynamic range. Perhaps the Supercharger is an answer to this dilemma.

You guys didn't get the point this is a marketing scam! You are trading transparency for power.

Putting one amplifier in series with another is not a great idea, hence even Carver stopped with it.

If you want the control of solid state with the musicality of tubes then you buy a tube preamp and mate it with a solid state amp.

There was another company marketing a distortion box which would make a solid state amp sound like a tube amp, this is no different.

I have heard the supercharger and it sounds like a good solid state amp period, however, if I was going to pursue Musical Fidelity I would buy a separate amplifier from them and not a super charger.
The supercharger increases the power of any 50 watt plus amplifier to over 550 watts rms so typical can't be used with low powered SETs.
Athipaul, like any amp that is added in series, the ultimate output is a function of the output of the 'last' amplifier in the series. So, as long as the SET amp has enough voltage to drive the following amp, low powered SETs can be used. Even 1/10th of a watt should be able to drive the Supercharger.
Still, what a strange way to get more power!?

Bob P.
Athipaul also came up with the info i found before.MF claims that.But Inpepi is right.In Stereophile they connected Supercharger with 18 W/ch tube amp.It worked just fine.

But has any SET owner out there tried this and can he make some comments on the sound changes?
As I mentioned in another post, I think one of the few systems that could perhaps benefit from this is MBL 101's. They can use alot of power to wake up supposedly.
FWIW the MBL 101s don't really need as much power as people think. Yes, they have low measured efficiency at 1 meter, but as soon as the speaker is put in a real room, the sound radiating in directions other than the one that the microphone was placed in all gets heard. You can add about 6 db to the result. 200 watts is enough power in many rooms.

Back OT: Its a fun idea, but the 'supercharger' will have a negative sonic artifact, one that anyone who values what tube amps do will hear in a heartbeat. I imagine its pretty transparent on transistor amplifiers, Res Ipsa Loquitur.
Could it be that the solid state amp is relatively transparent and thus able to pass along the coloration of the tube amps so beloved by the analog folks?

db, don't think for a minute that transistor amps don't have colorations too! My experience is that it is a rare transistor amp that does not also sound like transistors- I can count them on one hand. No wonder that a 'tube-like' sound is used as a complement in reviews of well-received transistor amplifiers

Tubes more closely mimic the rules of human hearing, and while they often have more distortion (not always mind you), they have less of the distortions that the human ear objects to: odd ordered of the 5th harmonic and beyond. The human ear can distinguish these harmonics in vanishingly small amounts.

In this case, the supercharger concept is alluring because you could potentially have a setup that has small tube amp sonic properties along with high power. The 'supercharger' adds its own colorations of odd-ordered harmonics of the type I just described, and its easily heard. Re-read my earlier comments in this context and you will have a clearer idea of what I was talking about.
Although it is probably similar to using a tubed preamp as a driver, the concept does make some sense. Although something is going to be changed in the translation, the article states that the interface between the driving tube amp and the MF amp is optimised, more so than the tube amp driving a pile of caps and coils through a crossover. This would help, so I think that it might work to get a pretty nice sound aka "Hybrid" sound and would be great to try with a 2 watt 45 based SET amp.

My previous post was intended mainly to pull the chain of the anlog folks, but it does have some rationale.

My doctorate was in psychoacoustics, my post doc in binauaral processing, but how tubes mimic human hearing escapes me. I think of tubes as introducing a distortion that many find pleasant, a rosey sonic picture if you will. As a lab rat (grad student), one of my jobs was to test and match pairs of 6L6 and KT88 tubes for the many Mac MC 60 amps in the lab. A big box of tubes and a tube tester was not my idea of fun.

Along the same lines, check out the 6Moons review of Nelson Pass's First Watt F4 current drive amplifier. 50wpc stereo, 110wpc balanced monoblocks. Although, the design can easily be scaled up or down from that output.

In the review, Srajan runs a couple of SET amplifiers into the F4 and compares the sound with the SET's/F4 on their own.
Hi Dbphd, the way that tubes operate closer to the rules of human hearing is through the lack of odd-ordered harmonics, which comes from greater linearity and less need for feedback. Feedback runs counter to the rules of human hearing (i.e. adds high order odd harmonics).

Human hearing uses high-order odd harmonics as a way to measure loudness. Our ears are so sensitive to these harmonics that fractions of a percent is easily audible. We hear them as a 'sheen', 'hardness', 'clinical', 'brittle' or 'chalky' quality in the reproduction.
I haven't published in nor even looked at JASA for several decades, so I am far from current. But evolution of the human auditory system occurs very slowly, over thousands of years. You have to ask yourslef why human hearing, a system evolved for avoidance of danger and communication, would be sensitive to high-order harmonics. What might the teleological explanation be for developing such sensitivity be? For example, we can explain interaural sensitivity to timing and level in the lower frequency range as providing localization cues that could be important for survival. But what value might high-order harmonics add to our lives?

Hi db, I don't think high-ordered odd harmonics do add to our lives. The current state of high-end audio suggests that they don't. Their rarity in nature might mean that less brain power is required to detect the change in volume, but what is important is not the 'why?' but the fact of 'what is'.

That we react this way is easy to demonstrate BTW. If you have access to test equipment, set up a sine wave and run it through an amplifier at 0VU and listen to the result. Now run down the volume, switch to square wave, and turn it up until you get the same perceived volume level. Now look at the meter- you will be about 20-24db down compared to the original sine wave. That's 1/100th the level or so depending on your perception. If you add a filter to filter out the lower orders, you will find there is almost no change in perception.

A good empiricist needs first assure an absence of artifacts in such a demonstration. The signal generator and transducer can be sources of spurious acoustics, especially with square waves. A fast scope can monitor a generator, but I don't know how to monitor a transducer to assure absence of artifacts.

DBphd - you have a really interesting background and it seems your discipline could really add alot to so much of what we discuss here.

If you ever get the chance to hear any atma-sphere amps you should.

You might be shocked to hear how different (and how utterly un-tube like) they sound compared to the Mac gear you are so intimate with.
Dbphd, its not empirical if you don't try...

I have to agree with Atma.Tubes do sound natural, and SS amps don't.I don't know how to explain it, but it is what i hear in a second.There are good SS amps, but they always (at least the ones i heard) lack timbre and natural-sounding vocal that SETs are known for