[Wodgy]

So you don't trust online reviews of solid state amps but you trust online reviews of digital amps? Seems odd. It's better to be wary. There is a lot of fishy stuff out there, and you should really listen for yourself before buying or recommending to others.

For instance, there are reviews online claiming that $50 digital amps you can buy at Target destroy mythical $1000+ setups. How likely is this to be true, given that the unit itself likely contains about $5 worth of parts, including the power supply? No one ever posts measurements.

From what I've seen, a lot of the online reviews of digital amps compare them not against their solid state brethren but against low-power, single-ended tube amps, such as EL84 designs. The thing is, in my experience they do have a lot in common. 8-watt single ended tube amps usually have nice highs but very little bass control, sounding slow and bloated. (Whether this is caused by a lack of power or a low damping factor I can't really say.) In my experience, digital amps sound a lot like that. They have smooth highs, and somewhat deep bass, but the bass is often soupy and uncontrolled. It's not surprising, since they tend to be underpowered and have a low damping factor. You can almost never find accurate measurements of digital amps, and many of the power claims are simply misleading. 100 watts peak? That means what in the real world? 20 watts continuous? Less? At what level of distortion?

The two amps I have are a Sharp SD-SH111 and a Sharp SD-SX10 (not sure about the model number of the last one). For the price I paid for the SD-SH111 ($150), it was a bargain since it plays DVDs and doesn't sound too bad, but there is no comparison between it and my current inexpensive favorite conventional amp, the Pioneer Elite A-35R (around $150), driving speakers. For instance, in my review of the SH111 I mentioned that I needed to use it with a self-powered subwoofer because the amp's control of low bass in my main speakers was poor. I agree with you that some of the low end solid state competitors sound terrible -- you've probably seen me relentlessly pan the NAD C320BEE which is clearly not worth the money in my opinion, but that doesn't mean they all sound bad. Shop around and audition. You may find that you prefer the digital amps, but in my experience the digital amps are no low-cost magic bullet. You tend to get what you pay for.

 

[ooheadsoo]

Very true, Wodgy. It's just that I've been burned on solid state so I'm kinda turning to digital. To tell you the truth, I haven't seen many user reviews of NAD and the like that say good things, just magazine reviews. The rest of the guys are just guys like me who tend to parrot what they've heard other people say. I've only heard one solid state amp that I've really enjoyed to date, and its price is way out of my reach. Btw, I thought only the Sharp SX series were digital.

Another thing: the amps that you hear sound like el34 big buck tube amps are the tripath class t amps. Of the ones I mentioned (teac, jvc, panny) only the teac is tripath. The jvc uses its own digital analog hybrid feedback system, and the panny is pure digital. People are driving their VMPS RM40's with the panny xr-45 and are very happy. http://www.vmpsaudio.com/rm40Pic.htm That's two 10" drivers and a bevy of planars. RM40s are notoriously hard to drive, as well. It's as anti-tube as a speaker can get. However, the bass control on the panny is supposed to be quite good. I find that kind of testimony hard to fight against, just due to the sheer massive "size" of it

Oh well, we'll have to see, eh? lan is driving his maggie mmg's, another notoriously hard to drive pair with his xr-25 and he's pretty satisfied. So I think it's safe to say that the tube-like comments only refer to the tripath based amps, and indeed, most of the positive tripath comments are being generated by horn users.

Edit: for reference, those rm40's are about 6 feet tall.

 

[erikzen]

Quote:

Originally Posted by ooheadsoo Do you need it soon?

No, just trying to do my due dilligence.

 

[ampgalore]

We are only seeing the first or the second generation digital amps.

Whereas analog amps have been a mature technology for decades.

I would wait for a fourth or fifth generation digital amp to come out before jumping on the digital amp bandwagon. By then all the quirks will have been worked out.

 

[ooheadsoo]

"Bleeding edge" is my middle name!

 

[soundboy]

Wodgy,

I haven't hear the TEAC digital power amp, but I am extremely intrigued given its $100.00 price tag. To be honest, it's between the TEAC digital amp and the upcoming Sony SACD changer competing for my last audio hardware purchase this year.

I have listened to the Panasonic SA-XR25 when it was available at Circuit City. Despite the less than ideal listening environment, it was very VERY impressive. Then seeing it actually out-powering similarly-priced HT receivers from Onkyo and Yamaha in a group review (with measurements) in Sound & Vision magazine, it was proven as the real deal.

I believe we are on the edge of a revolution in amplification technology. Yes, I think there are still issues to work out, such as the extra analog >>> digital >>> analog conversion when used with SACD/DVD-A players, but I believe this will be solved in time.

Regarding the $30.00 Sonic Impact digital amp available at Target, 6moons.com is reading a review. Boulder Cable Company has several "mods" available that can work with it.

 

[eyeteeth]

Quote:

Originally Posted by soundboy I believe we are on the edge of a revolution in amplification technology.

PS Audio's HCA-2 Digital Stereo Amplifier has been out for a few years already.
There is also the wonderfully named 'Flying Mole'.

http://www.flyingmole.co.jp/en/index.shtml

 

[soundboy]

eyeteeth,

By that quote, I meant that digital amps can be afforded by mass consumers. Will digital amps replace solid-state amps? Too early to tell, but certainly possible. The paradigm is shifting indeed.

 

[Sovkiller]

There is a common confusion while talking of Class-D amps, and digital amps, could anybody explain this, in details, please? I found this article browsing that explain some of the misnomer commonly found while talking about the digital amps. But I still have my doubts about the digital truth...IMO there is such a "digital amp" at one point the signal has to be converted to analog anyway, IIRC there is no transducer capable of accepting the digital signal as such, here is a part of the article:

"......The Truth About Digital (Class D) Amplifiers:

Firstly I'd like to point out that "digital amps" is a misnomer. There are two categories:

1.Analog-controlled class D. Switching amplifiers with an analog input signal and an analog control system. Normally some degree of feedback error correction is present.

2. Digitally controlled class D. Amplifiers with a digitally generated control that switches a power stage. No error control is present. Those that do have an error control can be shown to be topologically equivalent to an analog-controlled class D with a DAC in front.
Both use switching power stages and have high power efficiency as their most eye-catching feature.

Digitally controlled class D: dead end street.

Analog controlled class D: definitely the future, although you shouldn't expect it to flatten competition from traditional solid- state and tube amps by a tremendous margin......." etc.....

you could find the rest here

 

[Wodgy]

Quote:

Originally Posted by soundboy I have listened to the Panasonic SA-XR25 when it was available at Circuit City. Despite the less than ideal listening environment, it was very VERY impressive. Then seeing it actually out-powering similarly-priced HT receivers from Onkyo and Yamaha in a group review (with measurements) in Sound & Vision magazine, it was proven as the real deal. I believe we are on the edge of a revolution in amplification technology. Yes, I think there are still issues to work out, such as the extra analog >>> digital >>> analog conversion when used with SACD/DVD-A players, but I believe this will be solved in time. Regarding the $30.00 Sonic Impact digital amp available at Target, 6moons.com is reading a review. Boulder Cable Company has several "mods" available that can work with it.

I don't doubt that the Panasonic XR25 and XR45 are competitive with similarly-priced HT receivers from mass-market brands, which likely use analog chip amps. However, I'd be more interested in a shootout between a high-performance, good value conventional discrete amp like the Pioneer Elite A-35R (ironically cheaper than even the XR25) and one of the digital amps.

One of the reasons I'm skeptical of digital amps, including the Panasonic XR25 and XR45, is that they make ludicrous performance claims. For instance, the XR45 is claimed to be rated at 100 watts for each of 6 channels. Trust me, there's no way there are large enough heatsinks inside the slimline XR45 to dissipate 600 watts, and that's assuming the impossible -- that the amplifier is 100% efficient. Digital amps are efficient, but in the real world you'd realistically need heat sinks that are capable of dissipating 900 watts or more.

The problem is that digital amps are like car audio -- there don't seem to be any FTC standards mandating what manufacturers can claim. Hence the $99 car amps that produce 500 watts of power.

Another reason that I'm skeptical of digital amps is because the distortion numbers tend to be bad. I checked out the Panasonic XR45 web page this morning and it's rated at 0.9% THD. In comparison, that's more than 10 times higher than even an average discrete amp like the A-35R, and nearly 50 times higher than the NAD C272 (which I do like, though I pan the C320BEE relentlessly). 0.9% THD wouldn't be bad for a tube amp, but it sucks for a solid state amp. And the Panasonic has the upper hand to start with -- you'd think with a pure digital signal path the result would be lower distortion.

Anyway, the reason manufacturers are moving to digital is not for performance. It's for cost. Because digital amps are more efficient, they can build them for cheaper, with smaller heat sinks, in the slim-line cases consumers prefer, and because there are no standards mandating what they can claim, they're much better for marketing purposes. A revolution may be in the making, but it's not here now.

 

[ooheadsoo]

Distortion is not necessarily bad, particularly even order harmonic distortion, which may even be considered preferable. Tube amps measure poorly in distortion but it's even order, and many people prefer that sound. The distortion that these (good) digital amps make are reputedly of the good sounding kind, with the exception of the pannies, which people do not say sound tube like at all. Rather, it's supposed to have the best qualities of solid state amps at a low price. Wodgy, you don't think a wimpy amp could drive the rm40's do you? Those speakers take immense amounts of current to drive 4 10" woofers and a bevy of planars. I know people have driven the rm40's to 110db+ peaks when biamping using party mode with a single panny without problems. Unfortunately, these digital amps come with fans instead of heatsinks, but I also don't hear of the fan activating very often except with faulty units.

I also think a lot of people make way too much hay out of specs and numbers, like all the rmaa specs being put out lately. Do you think you could reliably point out a 0.5db peak in the 16khz area? That's what these people are comparing. I bet most people couldn't even point out a 2db peak reliably beyond 16khz. There comes a point where it's all relative. You can't hear any of it, it's just become a pissing contest. The car amps make my point. Those wattage specs mean squat. What about FTC regulated home theater specs? They mean squat too. Specs for the NAD C320BEE? They look ok, but they mean squat. Still sounds like crap, right? I don't think a distortion figure necessarily makes the sound of an amp.

We people with small wallets need to be optomistic! I'll go out on a limb again and see what this jvc is all about. I wish I could hear your pioneer a-35. Do you think good guys or maybe circuit city would have it?

 

[Sovkiller]

Quote:

.....One of the reasons I'm skeptical of digital amps, including the Panasonic XR25 and XR45, is that they make ludicrous performance claims. For instance, the XR45 is claimed to be rated at 100 watts for each of 6 channels. Trust me, there's no way there are large enough heatsinks inside the slimline XR45 to dissipate 600 watts, and that's assuming the impossible -- that the amplifier is 100% efficient. Digital amps are efficient, but in the real world you'd realistically need heat sinks that are capable of dissipating 900 watts or more.

Just to clarify something one of the virtues of the digital amps is the high efficiency, they are on the range of the 95+%, so you do not have to dissipate 600 watts. Sorry but you are assuming all the opposite, that the amp is dissipating the whole power, and you have an amp not an iron, the huge part of this power goes in the audio amplification and 5% or less of it dissipates in heat, and not only at the amp, voice coild get hot, cables get hot etc...assuming 10% of 600 watts, this figure is about 60 watts of heat, and you could disipate this with an small heatsink on each channel.....about the distortion as you say, if you go to tubes amps they are a lot bigger and some of them sells for thousands of $$$$ BTW 0.9% is not that bad for a 600watts amp this THD is usually at full power, you will not hear it at 20 watts....

 

[Wodgy]

I agree with you that specs generally bear little relation to sound, but there is a difference between honest and dishonest specs, and manufacturers that make dishonest claims tend to make me skeptical about the product. A small fan is just physically not going to be able to dissipate 600w+ of heat.

Also, I'm kind of curious about your claim that you know more than one person who is driving VMPS RM40s with the Panasonic XR45. The RM40s are $4600 speakers. It seems unlikely to me that you would know several people who have those specific speakers, and even more unlikely to me that they all happen to be using the same $350 amp for driving them, but hey, I believe you. It just seems odd to me.

Anyway, do check out the A-35R. My guess is that either Good Guys or Circuit City would have it. Look through the top. Unlike the NAD, which mounts all the transistors to the same heatsink (increased thermal crosstalk), there are actually four separate large heatsinks in the A-35R, one per transistor.

It is possible that digital amps do have low distortion levels at very low power levels, which is typical of tube amps and atypical of solid state amps. That would be a desirable feature. I'd be interested in seeing distortion vs. power graphs for a typical digital amp.

 

[ooheadsoo]

VMPS has a forum over on audiocircle, so there are quite a number of rm40 owners there. I believe it was at one of the Denver, Colorado audiocircle meets where a bunch of them got together to hear the panny 45 drive the rm40's in both regular and biamped fashion. Subsequently, I think more of them got pannies to drive their rm40's. Wayne of Bolder Cables brought the measuring gear and computers over, I think.

Sov makes some interesting points. Also, I think it's important to note that those 600 watts are not ALL being converted to heat. Wouldn't that mean that the amp was about as inefficient as a log? As Sov mentioned, the white papers state that digital tech is pretty efficient. Also, it gives me pause to think of anyone running 600 watts RMS into any normal set of speakers. If that were the case, there would be no room for dynamics...And everyone would be deaf in short order

 

[soundboy]

I wish either Circuit City or The Good Guys would sell the Pioneer Elite A-35R integrated amp. Between those 2 chains, they sell ONE stereo integrated amp....a Yamaha model at something like $500.00. The A-35R is probably one of the best-kept audio bargains/secrets out there and I would highly recommend it to anyone considering an inexpensive stereo integrated amp.

As for the Panasonic SA-XR25/45/50 HT receivers, almost all comments I have read about its spectacular performance involving it being used in a 2 channel setup. In fact, these receivers' HT performance is rarely mentioned. As for their specs, you can check out how the SA-XR25 did in a comparison test done by Sound & Vision magazine here. And the lab measurements here. It's rare for ANY receiver, at any price, to deliver its rated power to all of its channels at the same time. The Panasonic XR25 delivering 82 watts into 8 ohms, all channels driven, is actually excellent numbers. This from a 10 pound receiver with no vent on the top. Here is a webpage with lab measurements from Sound & Vision magazine regarding rated power vs. actual delivered power.