Difference between SS amps?

Why do they need to justify anything? Audio is hardly the only product category in which consumers are willing to pay different prices for the same functionality.

And "audible quality" is hardly the only criterion by which one might judge audio components. Visual aesthetics, build quality, technical (i.e., measurable) superiority, bragging rights, are all legitimate reasons to favor one component over another, even if they are functionally and audibly equivalent.

Look, you're lucky you see through the hype. You won't be wasting money on stuff you don't need. And yes, it's rather sad that so many self-styled audiophiles are paying for fantasy, not reality. But the world has bigger problems.

That is because it is neither difficult nor expensive to build an amplifier that has distortion levels that are insignificant, and orders of magnitude less than your speakers. Any distortion from the amplifier is swamped by the distortion generated by the speakers, and there isn't that much distortion coming from the amp in the first place (assuming we aren't talking consumer schlock to start with).

I generally agree. I had a denon AVR and was going to upgrade to an integrated, but choose not to, just upgrading to another avr with better features such as airplay, network connections, etc.

There is one area where some manufacturers can be better and that is in parts selection, worst case analysis (electrical stress), and quality control. Part quality can vary dramatically and parts can be used inappropriately by poor circuit design and finally they can be thrown together with little quality control. This will result in high failure rates for components. So while you might not hear sonic difference between amps there could be a significant difference in quality of the unit itself. At the far end of the spectrum is a Bryston. They offer a 20 year warranty on analog parts, 5 on digital.) After careful assembly they stress test each unit for 24 hours running a clippiing sine wave through it in one hour on/off cycles constantly heating and cooling the amp off. They are very expensive, but you can rest assured it will work. A lot of modern AVRs seem subject to relatively high failure rates if the threads in this forum are any indidcation. I have a denon 3311ci, and the hdmi board and network board seem to fail quite freqeuently. I've been fortunate in that regard.

So while sonic differences may not be there, there will be quaility ones. The had part is knowing where the point of diminishing returns is.

The audio market is all about perceived value, and it gets more that way the higher the prices go.

I've done my share of blind testing, and frankly one of the questions that presented itself to me once I had done a fair amount of testing is why the technical specs of things could be so different and the sonic results so much the same.

This launched me on a decade long study of human perception. If you understand how much information that the successful and highly regarded perceptual coding tools throw away, you get a clue about why measured specs with lots of leading zeros are meaningless.

Throw in how technically bad speakers and rooms are, and you've got the picture.



Perhaps the most interesting things for me is how people so easily and strongly perceive audible differences among things that actually are as sonically alike as peas in a pod.

First off, just about every listening comparison that almost everybody relies on is grotesquely flawed. The near-universal lack of level matching and quick switching are the two big stumbling blocks. As soon as people start listening with levels accurately matched and quick switching, most don't need any more bias controls to know that their world has just been rocked pretty thoroughly.

Throw in concealment of the IDs of what people are listening to at any particular moment, (IOW make it a DBT) and serious vertigo sets in for anybody who still thinks that audible differences abound after the level matching and quick switching.

Them's the facts and I've observed it for literally 100s of people of all ages and all backgrounds over an (amazing to me) nearly 4 decades.

As far as build quality goes, the actual quality of parts and construction is converging a lot faster than many would believe. I was looking at a $5K AVR the other day and 99% of what I saw said $300-500 AVR. Anodize the heat sinks and maybe have an industrial designer make them look different, and throw in a toroid in a nice round black metal case, and after that its mostly the front panel.

All of this gear is heading towards being a big empty box because once switchmode and class D take over, the size of receivers will all be about, you guessed it, perceived value. Take a look at a Sansa Clip+, and like it or not that's actually a fairly full function high performance FM stereo receiver/player with small power amps. The size of the power amps is pretty much the only difference between a Clip+ and a classic stereo receiver. That's where it is all headed!

Even though I agree that amps tend to sound alike, I still believe there are quality differences one should expect as amp prices rise. IMHO, Any company offering pricey gear for the very discriminating audiophile should make it a priority to:

* Ensure the volume control tracks properly throughout the entire volume range. You should not hear one channel go completely silent while music is still audible from the other - even if you need to hold your ear quite close to hear this. I realize this may be related to speaker efficiency, but the Amp mfg. knows the range of possibles, so engineer for it!

* eliminate ALL signal bleed b/w channels (example: music heard from tuner, when selector set on CD and CD player is paused and gain wide open

* Eliminate ALL hiss/hum that is audible when no source is playing, and gain wide open. Again, this may be related to speaker efficiency, but the amp companies know the range of possibles, so engineer for it.

* Eliminate ALL pops, clicks, thumps, etc.. one hears on cheaper gear when switching b/w inputs, turning the amp on/off, etc...

Things like "bass slam" and "prat" and "imaging", etc. are all nebulous, impossible to measure, and are likely attributable to expectation-bias. Yet, the things I've mentioned can be easily heard and give some hint as to how well something is built. ..IMHO.

I own the AudioSource AMP100 you mention and it exhibits ALL of the things I mention above. ..No big deal, as it cost $89! ..I also owned an NAD C375bee which exhibited NONE of those things, but it cost $1400. ..But did they sound different while simply listening to music and not scrutinizing it for these flaws? No. They sounded pretty much the same

Three words: digital volume controls


Three words: digital signal processing


In the extreme, mission impossible. In any practical way, three words: digital signal processing


Three words: digital signal processing

a buddy of mine has a b&k amp...his pre/pro and source components are on a dedicated circuit, while his amp shares a breaker with various outlets.

while listening one day, his wife turned on an appliance (vacuum, blender, don't remember) and kicked the breaker. two lamps in his listening room went dark, as the music continued...for about ten seconds. as the power led on the b&k slowly dimmed, the music gradually faded out.

aside from pointing out an obvious need to upgrade his breaker box, it was an impressive display of power reserves...

as for having an effect on sound quality...dunno

Amplifiers have different design and circuits. Some parts are just more expensive. Just look at the price of RCA connectors. They can be very inexpensive or very expensive. The design of some amplifiers handle things differently. Some may be good for low impedance loads. Others may not handle certain speakers well.

Noted was non-demanding 8 ohm speakers in the original post. Even such speakers can have swings in the impedance. My old B&W P6s in the secondary basement system are rated at 8 ohms but I believe have a minimum of 3.5 ohms. The room is very large (like maybe 650 square feet). I had an old Marantz SR7300 OSE (orig. spec. ed.) driving everything except the center channel (to give it some relief) for years and it sounded great. I bought a Pioneer 1120, which although had similar power ratings to the Marantz, really left something to be desired for both music and movies (a washed out sound). I moved the Pioneer to the (4.1) office systems and it sounds great driving old Mobile Fidelity OML-1s (which I believe are 6 ohm rated but of course they are in an average size room vs. the basement). I have an Onkyo 1008 in the basement now.

My main system for many years has consisted of Thiel speakers. For mains for a bit I had the 2.3s, then the 7.2s and now the 3.7s. They are not 8 ohms. They are all rated at 4 and the 7.2s are torture for many amps and the 3.7 are not a picnic either (I think the minimum per Stereophile's test was 2.4 ohms and they spend much of the band between 2 and 3 ohms). Even with the 2.3s, I had a Rotel amp (and the main room is big too with a 19 foot ceiling) and it would cause one channel to shut down often enough that I picked up a Bryston 4BST many moons back. The Rotel was much happier running 3 channels (I read a test report that said with only three channels running it was 304 watts into 4 ohms).

So in summary, not all speakers of a rated impedance will provide the same load.

just curious...what rotel amp were you using?

Back then - I believe the model was the RMB-1085 (5x100). I had Thiel 2.3s, a Thiel SCS2 center and PSB (8 ohm) surrounds at the time. The room is very large about 16x20 with a 19 foot ceiling and opens into other spaces. I had the Rotel pre/pro (I think the 980) and the system was much happier after the Bryston 4BST (about 400W into 4 ohms) and the Rotel driving the center and surrounds. I eventually upgraded the rears to Thiel SCS2s and then got the Thiel 7.2s as mains, the MCS1 center and the Bryston was pretty close to its limit in the room and I got Proceed electronics with an HPA amp which is 500W into 4.

If I had to do it all over again I'd just have a 2-channel system upstairs and a HT downstairs. I've gone the route of a 2-channel preamp with HT Bypass and have an Integra DTC 9.8 pre/pro at this point. I've gone through my fair share of electronics. Even a Bryston 14BSST (600W into 8 ohms and 900 into 4 and the test sheet showed 645W into 8 ohms) was not all that great with the Thiel 7.2s I had to build an amp stand with fans. It was better with the 3.7s but still would get extremely hot on one side. I've gone to Modwright electronics (KWA 150SE amp and LS36.5 DM preamp) in the main system. While the 3.7s are not the easiest load, they are fairly efficient (rated at 90db and tested a hair over that be Stereophile) and in a couple of years I will be in a bit smaller room (a drop smaller but also a 12 foot ceiling vs. a 19 foot) and will either use the Onkyo 1008 as a pre/pro and use its built in amps for the height and back channels or get something like it. The amps built into the Onkyo are pretty good and I have no doubt they'll be OK driving Thiel Power Points as height channels and Thiel SCS2s as back channels. They are both 4 ohm but not 4 ohm rated and have an impedance like the Thiel 3.7s. I've driven SCS2s with a Sony ES receiver several years back in the bedroom system.

It is a fact that different amps measure differently, with different amounts of distortion. But it's also a fact that once the distortion is too soft to hear, then all amps with distortion that soft or softer will sound the same. (Assuming an equally flat frequency response.)

--Ethan

Maybe, maybe not. The length of time an amp plays after power is removed depends on:

(1) The size of the main power supply capacitors

(2) The amount of current drawn for the given volume level which in turn may be highly dependent on the power level. Or, it might depend on bias settings. Do we penalize amps for running class A to higher power levels due to higher bias? If the amp was blasting away at top volume, it may have gone silent quite quickly, despite the fact that (1) was plenty.

(3) The voltage drop that the amp can tolerate before the amp goes silent. During testing long ago I found that while my now-ancient Dyna 400 would play well at reasonable power levels when the power supply was only +/-12 volts. Normal operating voltage was more like +/- 83 volts. Obviously, the amp would "coast" quite impressively despite its non-exceptional power supply.

A power amp may have a protection circuit that quite sensibly mutes the amp when the power goes down to say, +/- 50 volts. Since that should never happen under normal operating conditions, is that amp worse because it won't work with +/- 12 volts? I don't think so!

I happen to be of the viewpoint that all RCA jacks are junk. The reasons why are many and well known to many of us. If you want a real jack, you learn how to spell XLR. ;-)


If you want an amp that really does a great job on low impedance loads, shop carefully at the pro audio store. ;-)

[quote=arnyk;22094999]I happen to be of the viewpoint that all RCA jacks are junk. The reasons why are many and well known to many of us. If you want a real jack, you learn how to spell XLR. ;-)



I don't agree that all are junk. However, I do use XLR connections between the amp and the preamp and DAC and the preamp as I regard it as a better choice. I also have XLR connections between the pre/pro and the center and surround channels.

[quote=HighEndWire;22095106][quote=arnyk;22094999]I happen to be of the viewpoint that all RCA jacks are junk. The reasons why are many and well known to many of us. If you want a real jack, you learn how to spell XLR. ;-)

XLRs used to be impractical for more general use because they were expensive. The Chinese have learned how to make some good very cheap ones.

[quote=arnyk;22095153][quote=HighEndWire;22095106]
China is not the only one making reasonably priced good XLRs. Just go to jenving.se

Neutrik works for me!

Neutrik is good too as is Vampire. XLR when it snaps on is a good solid electrical connection with great noise rejection. When I use RCAs I like Neutrik ProFis. They are a fraction of Eichmann's or many of the WBT connectors.

The noise rejection is due to the differential circuits, not the cable or the connectors.

Agreed. What XLR brings to the table is:

capable of handling a balanced connection which RCA can never do
latches in place
no protruding contacts which RCA always much have
can be abused severely without loosing functionality
great implementations for a fraction of the price
hard plated (not gold) versions readily available

Are balanced connections sonically superior to RCAs? I understand there are durability advantages, but I don't unplug and plug in my RCAs very often.

Then you have nothing to worry about. And if they ever fail, replacements are very, very cheap.

There are a number of things that affect the "quality" of an amplifier, including the use, and size of toroidal transformers in the power supply stage, the capacitance offered within the amplifier, the topology of the amp (class A, A/B, T?) the quality of the capacitors used (1% metalized poly caps? matched pair electrolytics? audio grade? blackgates? no-name chinese?) as well as things like the connections offered.. Does the amp have balanced inputs? What type and quality speaker binding posts does it have? Are the heat sinks provided in the amp adequate to keep the amp cool and distortion free?

These are things that make an amplifier cost more. In some cases like Classe, Pass Labs, etc, you're also paying for the name. I can understand an amplifier costing several hundred dollars. I can't understand one costing tens of thousands. Sometimes it's just what the market can bear.

The noise rejection of the differential connection is still there. You don't see XLR single ended connections, or equipment, so it is a valid answer since XLR = differential in this context.

Depends on the application, but generally no. In home audio, XLRs usually end up as line-level connections, where being balanced doesn't buy us that much that is audible. However, balanced connections usually provide measurable benefits.

It's not clear whether you are talking about sound quality or perceived value. Do tell!


There are some ironies about your list. For example amps for professional use generally have balanced inputs, and yet as a class of amps, they are generally less costly than home audio products with similar power ratings. They also generally have really robust output terminals, often with the classic 5-way binding posts and Speakon connectors in parallel. Aluminum extrusions for heat sinks are pretty cheap these days, and designing them for power amps is pretty much a cook book/ computer model project. I see no justification for exceptional pricing in any of these areas.

Agreed. They are generally very nice amps, but the pricing is out there, even given what is in the box.

Totally agreed. I think that around $0.50 a 4 ohm RMS watt is the border line between pricing for reasonable cost recovery and gouging.

Generally, within certain specified standards (namely playing at a given output power level well within the capabilities of the amplifier without reaching clipping or distortion levels) no, you won't hear a difference between amplifiers. When you will hear a difference, is when you push the amplifier to near it's limits, and you find out just how much headroom that power supply within the amplifier can offer. This is typically seen more often in car audio than home audio I'll admit, but it's still a valid factor to consider in regards to who a bigger power supply and bigger capacitors matter, so to answer you, both. It matters in perceived value, and at times, in SQ. The latter holds especially true when the amp is asked to drive highly reactive, very low impedance loads with speakers such as ESL panels for example.

I also disagree with yoou that balanced inputs are only seen in professional studio/PA type amplifiers. I see a LOT of quality home audio amplifiers offering XLR connections these days, such as Odyssey, Adcom, Emotiva, and others. There are also more flagship AV receiver models showing up as pre-pro models minus the amplifier stage, with both balanced and single ended pre-outs being offered on the market. The thing I didn't mention, is that with the short distances and line-level voltages you typically see in home audio, how important a balanced connection really is, well, is a matter of buyer perception. It isn't nearly as important as it would be in a studio setting, though, using higher voltage signal paths.

The point of my response, noting things like the aluminum heatsinks, is because the OP noted a comparison between a NAD amplifier (I think rack-mountable or stackable component amplifier, like an Emotiva, Adcom, Classe, etc) versus an AudioSource (read: Parts-Express pocket amplifier in a project box) so yeah, in that case, the cooling makes a huge difference. This holds especially true when you compare a Pure class-A (very expensive, mostly due to power supply again) to a class D or T or similar "digital" amp that is around 80-90% efficient, compared to the class A amplifier's 40-50% efficiency, and need to dissipate the heat of all the additional power used, and put off by the finals.

Is that bridged or in stereo, Arny?

I was just explaining to my wife why I bought the Bryston for the front speakers in the home theater instead of another Adcom. The Bryston puts out 330WPC into 8 ohms, 1008W in bridged into 8 ohms. I don't know what it does into 4 ohms. According to your formula, I overpaid significantly. I told my wife I knew it was a splurge, but cited build quality, warranty, aesthetics, etc, to justify the cost. You really can't put an Adcom on a pedestal between your speakers.

I feel a lot less silly than I would, if, like my buddy, I'd bought the Ayre VX-R, which is 200WPC for $15K. That's just crazy.

Stereo. Bridged 4 ohms (which many pro amps handle) would cut the costs even further.
Not to make you feel bad but...

A more typical example - a Crown XTi 2000, the last two of which ran me less than $500 each.

Stereo, 2 ohms (per ch.) 1000W*
Stereo, 4 ohms (per ch.) 800W
Stereo, 8 ohms (per ch.) 475W
Bridge-Mono, 4 ohms 2000W*
Bridge-Mono, 8 ohms 1600W

The two power ratings with asterisks should probably be derated by 5-10% for HiFi purposes.

No, they aren't particularly pretty:




The XTi series amps have DSP built in, which allow one to obtain the function of electronic crossovers, parametric equalizers, etc. for no extra cost.

Or...
Behringer EP4000 @ < $400




8 Ω per channel 550 W
4 Ω per channel 950 W
2 Ω per channel 1250 W