Whatever Ralph meant the mid-fi comment did make me laugh knowing that
the sound I hear from practical Class D amps today (like the ones I own
which are neither the least or most expensive) is not mid-fi by any
reasonable listening standard.
@mapman Do you think that because we've taken this technology very seriously that at the same time we don't?
If I can point out some things without people trying to put words in my mouth, first- tube amps are rarely mid-fi. The term 'Mid-fi' refers to equipment generally sold in box stores like Best Buy (not including their in-store Magnolia dealerships); stamped out to make money. Tube amps are usually too expensive for that (tube power is generally expensive, which is why there were many high efficiency speakers on the market when tubes were the only game in town decades ago).
The thing about most solid state is that the specs really haven't changed a whole lot since the late 70s or early 80s. Like I said, compare a Kenwood amplifier a Krell and you will see what I mean. The big difference is power (on paper). Bandwidth and distortion are almost the same. Of course a Krell is built better, has bigger heatsinks and bigger power supplies. And its not sold in box stores.
Class D has almost entirely taken over at the bottom end of the audio market. And the middle part too. You can't buy a boom box now days that isn't class D. For the number of class D amps in total on the market, only a tiny minority (the ones that generally have our attention) are considered high end. Many of them use the same modules found in mid fi gear.
Think about that for a moment before railing on me? I'm only working with the facts here so don't shoot the messenger. If you look at a high end tube amp or a traditional solid state amp, **NONE** of them use parts/circuitry/assemblies also found in mid fi gear. This is something different about class D and has entirely to do with how inexpensive the technology actually is.
(To give you an idea of that, I have a module on my desk that was sent to me by a customer (who happens to be the vice president of Phillips Semiconductor). This was one of their best modules built about 12-13 years ago. It makes 100 watts per channel and is a stereo module that is complete except for the power supply. It even has connectors on the board for easy hookup. The specs are quite good (Phillips TDA8920B, scans at 317KHz!; not bad for decade-old technology; faster than some amps made today and features no 'dead time') and it sounds alright too. In quantities of 1 it cost $25.00. I know of at least one 'high end' amp that uses this module that cost $2500.00. This module is the size of a pack of cigarettes complete with connectors and heatsink.)
So when I talk about mid fi and class D, you **should** know why now. I think a lot of posters here are attaching a negative meaning to the 'mid fi' term that does not exist; Just because its mid fi does not mean it has to sound bad and I can point to plenty of examples (we could start with the Radio Shack Lineaum speakers). What I'm seeing in class D is something I've not seen in audio before- amplifiers that use the same parts as a mid fi amp as in a high end amp. In fact its safe to say that class D has lifted mid fi performance to what many would have called 'high end' only a decade earlier.
So you might like your amp and I'm not disputing that! OK, I'll say it again, you might like your amp and I'm not disputing that. But if you think that the amp does not share a lot with mid fi gear you are ***really*** mistaken.
There is one other thing that keeps getting left out of this discussion. Its a simple fact that no matter what the amp is, if you make it work hard for a living its not going to sound as good because its distortion will be higher. This is easy to hear and easy to measure!! You can see it in the specs of any amp. Tube amps in general are best experienced when driving higher impedances 8 ohms or more. All output transformers are more efficient driving higher impedances and also will have wider bandwidth (its not unusual for an output transformer to loose an octave of low frequency bandwidth going from the 4 ohm tap as opposed to the 8 ohm tap). For this simple reason, Magnaplanars and Ohm Walsh loudspeakers are not the best candidates to really tell how good a tube amp actually is (the tube amp will sound better on a load that's easier to drive, and so will any solid state amp). My speakers at home and here at the shop are both 16 ohms and very different designs; both extremely transparent. When both amps are on a level playing field their differences are more easily assessed.
At any rate, if you are happy with what you hear than that's really what's important. If you have audiophile nervosa, which is a deadly disease (I've had it for decades and its no picnic) you are always left wondering what's around the next bend, how you can arrange things to get better sound. I've outlined already how class D has to improve (FWIW, some of the complaints I have apply to regular amps as well), which we hope to address in our design.
