Macgyver,

I saw that you mentioned transfer function a couple of times in the other thread. I'm not intimately familiar with the transfer function but I'm wondering if what you were referrring to is what I'm thinking of. About 10 years ago (I think) Bob Carver (one of my idols) developed a solid state amp that he said would sound great to the most discerning audiophile. He said the sound of the amp was shaped by the transfer function and he had developed a tunable transfer function. His amps were subsequently compared head to head against some esoteric, high end tube amps by Audiophile magazine. Bob Carver was allowed to tune his transfer function to match those amps and his solid state amp ended up being indistinguishable from the tube amps. Is this the same "transfer function" you've been referring to?

 

I won't guarantee it, but I can't imagine a reason he would be talking about anything else.

The transfer function is merely a mathematical description of what will happen to a signal as it moves from the input of a system to the output of a system. Capacitors, resistors, inductors, etc. all add a component to this equation, and do so in ways that depend upon how they are installed in the circuit.

The explanation behind the mathematics involved are probably beyond the scope of most who lurk here, but suffice it to say that it is nothing more than algebraic manipulations (OK, OK, so there may be some calculus or differential equations needed for analysis, but let's not quibble about the details on this one).

Many out there love the "smooth sound" of tube amps, and prefer it to the "hard sound" of digital and solid-state analog amps. I think I would call Carver unique, for his time, in using the modifiable transfer function in his marketing strategies, but everytime someone tweaks a component in the audio path, they're modifying the transfer function. I don't want to over-simplify, but technically, everytime you adjust the amp gain knob you're modifying the transfer function.

There have been countless articles over the years about how to simulate the sound and fgeel of a tube amp using solid-state tehnology. All these articles are showing is how to take the transfer function of the "usual" amps of today, and adding/deleting components until the new transfer function matches that of a "common" tube amp. It's a fun thing to play with, but I personally don't see the point. My ears aren't that golden to begin with, and I can tolerate a wide range of different sound "feels" from different types of amps...I like solid-state over tubes because they're compact, but they both sound nice to me.

 

I took a class on transfer functions back in college for my engineering degree. Lots of Calculus and Differential Equations.

 

I agree. I'll take a solid state amp over a tube amp any day of the week, unless I live in a super cold climate and want the added benefits of a space heater . It sounds like we are talking about the same thing. The reason I remember this was after the "contest", Audiophile magazine recognized that Bob Carver had in fact made his solid state amp sound exactly the same as an esoteric tube amp there was a huge run on the amp by readers of that magazine. They found out, to their dismay, that the amp didn't sound like the tube amp they thought it would. When the magazine asked Bob about this he told them he made the amp sound that way for the purposes of the contest but that he never promised that the production models would sound that way. He made the production models sound the way he thought was best. It started a riff between him and Audiophile magazine that went on for as long as I was reading the mag, at least a couple of years. It was a good old flame war just like we see here from time to time .

 

A transfer function is a mathmatical equation describing the output of a signal block divided by the input. He sold those amps (I believe called Silver Something) for a lot of money. Some people liked the sound.