Axiom Home Page Forums General Discussion Home Theater Cool amps

OK, here's a question for y'all. (no, I'm not buying anything anytime soon...) Is it possible to make a cool running amp? Are there any extant today? My H/K 525 (7x75wpc) runs hot just sitting in the cabinet doing nothing. Seems like such a waste of power. I'm guessing the A1400 runs much cooler, but that's a biiiit out of the price range of many (myself included).

Yeah, I was gonna say that I thought digital amps, like the Axiom, run relatively cool. I'm not gonna be much help cuz, off hand, I don't know of any other digital amps. I suspect they exist, I just don't know about 'em.

They exist, but they're reputed to be problematic, from what I know. Or at least from what I know from reading the A1400 reviews...

Wyred 4 Sound supposedly makes a good digital amp as well as Nu Force. All are somewhat pricey, but that is in the eyes of the beholder.

Hi kcarlile,

Class A/B analog solid-state amplifiers are about 50% to 60% efficient, so yes, they do waste lots of power, but at least we can console ourselves that we're not using vacuum tubes! You can warm up dinner on top of most tube amplifiers; in fact, tubes don't even work until the heater element inside heats up (that's what gives off the orange glow so beloved of tubo-philes) and stabilizes so that the electrons will flow.

Anyway, digital amplifiers like the Axiom A1400, which I have, run tepid or warm, but never really hot (like those old H/Ks, which I also have!), because as their output increases, they become more efficient (at near full output, the A1400 reaches about 95% efficiency).

The ICE digital amplifiers developed and licensed by Bang & Olefson (Pioneer uses them in some of their receivers) also do not run hot. Panasonic has made some really cheapo digital AV receivers which should run cooler than analog, but I've never had experience with them.

The real problem is sticking seven amplifiers plus all the preamp circuitry inside of one chassis. In the stereo days, you just had two amplifiers to worry about, and reasonable heat-sinking would keep them from running hot. But now, unless you put either a cycling or constant-running cooling fan into a 7-channel class A/B AV receiver, it's going to cook!

Regards,
Alan

If you don't want to risk the problems that come with most digital amps, you can look into type-H amps. They run much cooler than A/B amps, but usually run more than their A/B counterparts. The Emotiva MPS-7 is a good example of this sort of amp (http://emotiva.com/mps2.shtm), read up on it.

Like I said, they are more than A/B class amps, but not quite as pricey as the A1400... well, at least the Emotiva wasn't! lol

Second that. My GX5 is Class-H and runs very cool on the low rail. But once your want to feel the music, it gets hot via the high current rail. As expected, I don't know what any of that means, but I know it works!

From QSC:

I would not recommend Emo with Axiom m80s.

Yeah, Instead get something like Odyssey Stratos mono's... which will run cool due to their massive heat sink's. There arent even any vents in the chassis.

Ken, the NHT amp I'm using is a 200X5 with B/O Ice Power Modules in it. It runs cool. Heck, I even have the 3808 sitting on it and it still runs cool to the touch.

Micah,

There is nothing new about class H (or class G) amplifier designs (they are similar), which have been around since the late 1970s. The first class G design I recall was developed by Hitachi. It used two voltage rails, a lower-voltage supply for lower power output, then, when music signals became large, the amp would momentarily switch to a high-power voltage rail and a second set of output devices. A class H design is a variation of class G, and uses a power-supply input-tracking circuit, so on peaks the power supply delivers enough voltage to allow the amplifier to briefly deliver much more current to handle the peak without clipping. In both class G and class H, the amplifier runs cooler so long as signal levels remain small.

Class G designs were never that popular in home audio because it was feared that the voltage-rail switching would add distortion when it switched to the high-power output devices. Both class G and class H are quite popular in professional applications.

Incidentally, there are not "problems that come with most digital amplifiers"; properly designed digital amplifiers have many advantages, however, they tend to be relatively expensive.

No amplifier design is perfect, however. Each amplifier class has distinct advantages and disadvantages.

Regards,
Alan

Brandon, as much as I appreciate the enthusiasm for the Odysseys, huge heatsinks means that it's generating a lot of heat, and that heat has to go somewhere--into the heatsinks, and then into the surrounding air. Heatsinks cool the thing they're attached to, not the enclosure or device itself.

I believe the Outlaw M2200 run cool and are relatively inexpensive.

What reasons are there for NOT choosing Emotiva for an M80 setup?! Their site says they are coming out with a new multichannel amp within the year.

Call Lonnie @ EMO, he personally told me they are not a good match and refunded my money after 2 failed (blown channels) RPA-2's in a row. Customer service was excellent however. Remember, this is just "my own experience". Others have no issues whatsoever.

For what it's worth, you can read about my whole story here:

http://www.axiomaudio.com/boards/ubbthreads.php?ubb=showflat&Number=263595#Post263595

That amp is an AB; the reason it is able to run cool is because it is only a single channel. Nothing wrong with a monoblock (and quite a few things right), except they generally cost more in the end than going with a multi-channel amp. But you know each amp has its own separate power supply, and you can locate them very close to each speaker.

Just this weekend we heard M80s with EMOs XPA-1 monoblocks. No trouble there!

Wow, you know I'd read about the XPA-2 not working out so well with the M80's, but I'd never seen this thread before. I guess I'm lucky the RPA-2 wasn't available after all. Well here's hoping the XPA-3 doesn't have the same issue's with the M80's as some of Emotiva's other amps have had. I would truely hate to have to go down a similar road as you had to travel.

And while your story started to make me wairy of my Emotiva purchase, I think back to the last time I felt this way... that would be after reading Bob's thread on Axiom's. I was just about to make my purchase when I read about his disappointment and unsatisfactory experience with his speakers. It made me seriously doubt my choice in brand decision making. But here I am 2 months after making the call to Axiom, and I couldn't be any happier with my choice. Every company out there has a customer with a similar story as you have. So I won't hold it against them.

Heck just look at me. I have an EP800 that has had 3 out of 3 components go bad in it. Potential Axiom customers might read my story and decide the EP800, or even Axiom as a company, is too risky to deal with. But that would be a shame, because dispite the set-backs, I'm convinced there are few companies out there that put out as good a product as Axiom puts out. And to your credit you haven't tried to smear Emotiva, you've mentioned this is a 'personal experience', and that there are many other satisfied Emotiva customers out there, including in this forum.

So I won't sweat it unless I experience a similar problem as you.

I wouldn't sweat it either Micah, I'm sure the XPA-3 will be fine. Actually, I'm glad I had to go thru my ordeal. If I didn't I wouldn't have ended up with my odyssey mono's, which so far I am extremely happy with them.

Even if something goes wrong, you will be in good hands with Emo.

Good luck and enjoy!

Dduval