Current amp vs Voltage amp

Why aren't more manufacturers making powered speakers, and why is it that people don't seem to buy them.

Lots of reasons come to mind. Charles mentioned an important one.

Let's say that a passive speaker is designed such that it will perform optimally, in a typical room, with an amplifier having a certain output impedance, a certain amount of feedback, and a certain power capability.

Separate power amplifiers meeting those criteria might range in cost from say $500 to $100,000. Their size, weight, and design philosophies will vary enormously. If the speaker manufacturer were to design a speaker incorporating an amplifier meeting the impedance, feedback, and power criteria, how would he choose among all of those kinds of possibilities without greatly limiting the number of potential customers?

Also, the size and weight of the speaker is likely to increase considerably. Its physical complexity and its appearance will change. WAF is likely to decrease considerably. Microphonics would have to be addressed in the design. Finally, the expertise required to design speakers is obviously very different than the expertise required to design amplifiers. As might be expected, there don't seem to a lot of high-end companies capable of, or even interested in, producing both kinds of products to a high standard. Israel Blume of Coincident being a notable exception.

Regards,
-- Al

Al,
Israel Blume is one of the very few.
MBL,Gryphon and Tidal for example build power amps and speakers.The problem, some like their speakers but not necessarily the amplifiers to match them.Again, the reality of being limited to a particular voicing chosen by the builder.Al you list many other good reasons against the universal practically of powered speakers.
Regards,

The only disadvantage I can see is a service issue. If one of that amps fails in an active speaker system you lose both the speaker and the amp vs. just one or the other in a passive system. Remember, in an active speaker system the filters for the crossover can be active.

Another thought on the powered speaker issue (btw, I love the NHT powered speakers I use at my computer)is that they don't appeal to the tweaky gearhead side that exists in many of us that the high end market is geared (pun intended) toward.

Powered speakers are like an albatross around your neck.

If you want more power, you can't. You have to sell the amps *and* the speakers to upgrade.

I have to agree with Bombaywalla. Some manufacturers of ESL's specifically made/make ss amps for use with their speakers, Acustat and Sanders come to mind. Many ESL manufactures use ss amps when demonstrating their speakers. I remember a particularly fine demonstration of Martin Logan's with Threshold amps.

'Many ESL manufacturers'. A bit cumbersome to be a real oxymoron, but nevertheless it is an oxymoronic phrase. And a bit of a red herring, there are not 'many' ESL manufacturers :)...

There is more going on here than meets the eye. ML and Sanders (the Acoustat powered speaker used a tube amp) are both trying to make their speakers work better with transistors by reducing the impedance of their speakers (unfortunately, Quad has been treading this path in recent years too). To this end you encounter some very low impedances (0.5 ohms to 4 ohms) with them. However if you can get around the impedance problem (with a set of ZEROs or the old Atma-Sphere Z Music autoformer) what you find is that the tubes sound better even on those speakers. Sure, such and such a speaker might have sounded 'fine' with a transistor amp, did you then compare it with a tube amp in such a way that that the tube amp was not having a problem with the load? Just because a speaker sounded 'fine' is not the same as it sounding its best.

The old Quad 57s and 63s, as well as most Sound Labs and some Acoustats, have impedance curves that vary from about 2 to 30 ohms or more. Usually if someone with such a speaker and a transistor amp claims that it makes bass, its because the speaker is too close to the wall. They are not winnowing out the performance of the speaker in that fashion.

Paul Speltz, who make the ZEROs, has a letter from Steve McCormick, who makes (or made) the McCormick amplifiers like the DNA1. In the letter, Steve states that while the amp can easily double power into 4 ohms, it actually sounds better driving the 4 ohm load through the ZEROs (meaning that it is seeing 16 ohms).

If you interview solid state amp manufacturers, you will find that they will pretty much agree on this point- just because they can double power into 4 ohms does not mean that they are sounding their best, and you can see that in the specs on any solid state amp- the distortion is higher as the load impedance is decreased.

Essentially, if the goal is the audio *quality*, there is no argument for four ohms or less. If sound *pressure* is the goal, then 4 ohms has a weak argument. Looked at another way, a simple means of making your speaker sound smoother and more detailed is to increase its impedance, not because the speaker will work any differently, but because the amplifier will.