Let's Talk About Amplifiers

BClarkeVA

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Related topic - bi-amping. My FR and FL speakers are Legacy Signature III towers, and I noticed Legacy always runs them bi-amped at audio shows. So I began to use the bi-amp capability in my Onkyo receiver, which effectively doubles the available wattage to each speaker. Sounds to me like there is more headroom.

Looking ahead to my next upgrade (as most HT folks do), I'm torn as I want to go to an AVR that will support a 5.2.4 Auro 3-D environment with at least 125 WPC, but I also want to be able to bi-amp the FR and FL Signature IIIs. That would require at least an 11 channel AVR or amp, and maybe more as at least in my Onkyo, the channels aren't entirely configurable.

BTW, my analog system is based around a Conrad Johnson MV-75a amp - Tubes Rule! But aren't practical for home theater, IMHO.
 

JohnRice

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So I began to use the bi-amp capability in my Onkyo receiver, which effectively doubles the available wattage to each speaker. Sounds to me like there is more headroom.
Well, yes, but not really. More power is available, as long as the power supply isn't being extinguished, and even if it isn't, the real-world gain in power is more like 15%, since the lion's share of power is going to the woofers. But that's an entirely different topic, and now I went there...
 
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Dave Upton

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Well, yes, but not really. More power is available, as long as the power supply isn't being extinguished, and even if it isn't, the real-world gain in power is more like 15%, since the lion's share of power is going to the woofers. But that's an entirely different topic, and now I went there...
I'm going to re-post my comments from another thread here re: damping factor:

Overhead and extra power is nice, but there is another huge factor here that isn't being discussed: transient response and damping factor.

Even a highly efficient transducer like a (horn) Klipsch or 1-way coaxial speaker will still have moments when it needs significantly more power - largely during movies rather than music. With an efficient speaker, it's less likely you'll run out of headroom on a good amp, but an amp like the D-Sonic pretty much guarantees it.

The other side of this, which has next to nothing to do with power or sensitivity, but correlates to power is the damping factor of an amplifier. The D-Sonic amps have one of the highest damping factors on the market. What is damping factor? It's the electrical ability to put the brakes on a woofer that is already at peak excursion and bring it back to a resting state. This directly correlates to the tautness of bass and how much "punch" your speakers will have.

John's XPA-DR2 has a damping factor of >500. The D-Sonics are >1000. To me, this is probably the "secret sauce" with the D-Sonic amps that has kept them in my system. There is just no comparison between a tom or kick drum reproduced by these vs any other amp I have heard.

Dennis of D-Sonic has a great summary of watts/power on his site that I think merits quoting here:

Watts— can you have too many, especially if they are accurate and musical? It is better and safer to have too many instead of not enough.
400, 800 or even 1500 watts into 8 ohms might sound excessive for some systems, but for most, they are generally a solid plus. 1500 watts can pressurize a large room with inefficient speakers. What’s dangerous is the opposite. Too few watts can damage your speakers and sound very bad long before they reach that level. Clarity is the goal regardless of sound pressure level (SPL).

Speakers are somewhat self regulating. Put too many watts into them and they play so loud you’ll naturally turn the level down well before the onset of trouble. Almost all speakers are capable of dynamic peaks far higher than their rated wattage since they are of short duration.
Under-powering a loudspeaker is where we risk clipping. Clipping the audio signal means we have exceeded an amplifier’s ability to reproduce loud passages. When this occurs the amp’s output signal wave is now flattened at its peak creating a burst of transient energy that is damaging to tweeters and mid-range drivers.

Lower powered tube amplifiers tend to clip gracefully because they do not have the energy or bandwidth to produce a driver-threatening peak, but they will never reproduce the visceral dynamics of wide range, exciting source material. The leading edge of a high amplitude sound wave can require many thousands of watts for a few milliseconds to reproduce this sense of realism. I prefer the sonic ease and added headroom of stronger amps to the weakened potential of low-powered units.

The added headroom, increase in linearity, effortless presentation and freedom from potential damage an oversized amplifier presents to your speakers is generally always the best way to go when assembling a first-rate system.
 

JohnRice

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I'm going to re-post my comments from another thread here re: damping factor:

Overhead and extra power is nice, but there is another huge factor here that isn't being discussed: transient response and damping factor.

Even a highly efficient transducer like a (horn) Klipsch or 1-way coaxial speaker will still have moments when it needs significantly more power - largely during movies rather than music. With an efficient speaker, it's less likely you'll run out of headroom on a good amp, but an amp like the D-Sonic pretty much guarantees it.

The other side of this, which has next to nothing to do with power or sensitivity, but correlates to power is the damping factor of an amplifier. The D-Sonic amps have one of the highest damping factors on the market. What is damping factor? It's the electrical ability to put the brakes on a woofer that is already at peak excursion and bring it back to a resting state. This directly correlates to the tautness of bass and how much "punch" your speakers will have.

John's XPA-DR2 has a damping factor of >500. The D-Sonics are >1000. To me, this is probably the "secret sauce" with the D-Sonic amps that has kept them in my system. There is just no comparison between a tom or kick drum reproduced by these vs any other amp I have heard.

Dennis of D-Sonic has a great summary of watts/power on his site that I think merits quoting here:
Dave, do most amps even publish a damping factor?
 

Dave Upton

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Dave, do most amps even publish a damping factor?
Typically, only the ones that have a value to brag about, so more in the Class D space.

You will find a lot of very expensive audiophile Class A/AB amps don't publish this. A good example of brands that have poor/low damping factor:
Naim
Dartzeel
PS Audio
Constellation
Most Outlaw Audio and Emotiva amps are actually quite low damping factor

The amp makers who do have good damping factors and tend to brag/publish them:
ATI
Bryston
Anthem
Classe
ATC
D-Sonic
Emotiva (new stuff)

You know who also consistently has really high damping factors? Pro sound amp makers. You can't drive a line array or bass bins without high DF - or you get mushy, squishy bass that has no impact.

Crown
Lab Gruppen
Powersoft
QSC
 

JohnRice

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You know who also consistently has really high damping factors? Pro sound amp makers. You can't drive a line array or bass bins without high DF - or you get mushy, squishy bass that has no impact.

Crown
Lab Gruppen
Powersoft
QSC
..and those are all Class D, aren't they?

I said in another thread that it makes sense a Class D amp would be capable of high damping factor, since by their design they only run at 100% or 0%.

Also interesting that it's the new Emotiva stuff, which don't have the vaunted toroidal power supplies, but have "inferior" switching power supplies, which excel in this sense.

I just want to add that there are a lot of factors which contribute to the sound quality of an amp, and damping factor is only one of them.
 
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JohnRice

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OK @Dave Upton , riddle me this. Would you speculate that high damping factor might be more important in the front stage of an HT, less in the surrounds and maybe even less in overhead/Atmos channels?
 

Dave Upton

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..and those are all Class D, aren't they?

I said in another thread that it makes sense a Class D amp would be capable of high damping factor, since by their design they only run at 100% or 0%.

Also interesting that it's the new Emotiva stuff, which don't have the vaunted toroidal power supplies, but have "inferior" switching power supplies, which excel in this sense.

I just want to add that there are a lot of factors which contribute to the sound quality of an amp, and damping factor is only one of them.
Absolutely - it's an important, often overlooked factor but it's not everything.

Most important to me is imaging, transparency and detail retrieval. Many tube or older class A designs have high IMD or THD that results in a syrupy sound that some like, but is ultimately lower in resolution. Many find newer class D or H topologies "harsh" because they don't mask any of the recordings flaws.

When you look at an amplifier, the type matters.

Class D amps are all about the input stage - since the modules are just OEM from Pascal, B&O (IcePower),Hypex or a few others. If you have a really good input board your class D amp will be special. The modules themselves are all designed to measure extremely well.
 

Dave Upton

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OK @Dave Upton , riddle me this. Would you speculate that high damping factor might be more important in the front stage of an HT, less in the surrounds and maybe even less in overhead/Atmos channels?
Absolutely. In a HT, you want damping factor and peak power to be highest in your largest transducers with the highest excursion (Xmax) so first subwoofers and then your LCR channels. The rest are of lower and lower importance as they have smaller transducers with lower Xmax and typically less activity.

This is why I really wouldn't want any less than 800W feeding my LCR in my theater, because now that I've compared it to the lower powered amps, it's a night and day difference.
 

Dave Upton

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Absolutely - it's an important, often overlooked factor but it's not everything.

Most important to me is imaging, transparency and detail retrieval. Many tube or older class A designs have high IMD or THD that results in a syrupy sound that some like, but is ultimately lower in resolution. Many find newer class D or H topologies "harsh" because they don't mask any of the recordings flaws.

When you look at an amplifier, the type matters.

Class D amps are all about the input stage - since the modules are just OEM from Pascal, B&O (IcePower),Hypex or a few others. If you have a really good input board your class D amp will be special. The modules themselves are all designed to measure extremely well.
To add on to this comment, I'm not saying Class A amps have higher distortion - i'm saying some old designs do. What's really hard to do with Class A (read: expensive) is to have high power AND low distortion. The sweet spot tends to be lower power.

A good example of this approach in class A is the below amp:

Schiit Aegir: https://www.schiit.com/products/aegir

If you look at the SINAD measurements Amir does at ASR (which is not a great way to evaluate equipment, and I don't recommend), it does tell a useful story if you look at the list. The vast majority of these designs at the top of the chart are Class D. The ones that aren't are more expensive class A designs:

Power Amplifiers.png
 

JohnRice

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Most important to me is imaging, transparency and detail retrieval.
I'm with you there. #1 for me has to be an amp that can tame the wild beast of my Thiels. It needs to resolve, but not exaggerate, since those things are ruthless with even slightly bright electronics. But the reason I bought them is for imaging. A rich, full, wide, deep sound stage that wraps around you.
 

John Dirk

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This is the type of discussion I was hoping for with this thread!

The input stage applies "gain" to the signal, which is what makes the signal "louder".
So adjusting you pre/pro's [or AVR's] volume control does nothing more than increase the input voltage that is eventually fed to the amp stage?

I went with Outlaw audio. 200w per channel. If I were to do it all over again I'd get 300x per channel.
With a Class A/B design (such as the Outlaw model 7900) 300 WPC x7 channels will require dual 15 amp circuits. One of the reasons I'm looking at Class D if i decided to go that route but I'm thinking I may be fine just adding headroom to the LCR channels and letting my model 7140 drive the others.
 

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So adjusting you pre/pro's [or AVR's] volume control does nothing more than increase the input voltage that is eventually fed to the amp stage?
Actually, it only reduces it. At least in traditional equipment it did, so let's just stay with that. Traditional volume controls were simply variable attenuators. It's a little more complicated now, the attenuation is digital, and your system calibration further adjusts the level of each channel, but really all you are doing with the volume control is reducing it to the playback level you want.
 

JohnRice

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With a Class A/B design (such as the Outlaw model 7900) 300 WPC x7 channels will require dual 15 amp circuits. One of the reasons I'm looking at Class D if i decided to go that route but I'm thinking I may be fine just adding headroom to the LCR channels and letting my model 7140 drive the others.
Interesting detail. Manufacturers are required to provide the ability to drive amps at full power, constantly, long term. So, the 7900 has dual A/C inputs, and it wouldn't be a bad idea to connect them to different circuits. A Class D amp will be the same, because power out requires power in. You'll notice several of the D-Sonic amps have 20 amp connections. The thing is, you will never, ever, EVER, draw what the amp is capable of long enough to really cause problems. With your Klipsch especially. Those peak power surges last a second or less. Your house's circuitry won't even notice. Is it ideal to have at least three dedicated 15 amp circuits in a serious HT? Sure. I get away with two just fine, and I do distribute the demand between the two that were already in the room.
 
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John Dirk

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So it occurs to me that my system can sound anywhere from incredible to atrocious depending on the source material I feed it. I figure I'm not in the minority in that my music collection is a hodge-podge of digitized material collected over many years and of varying quality. Of course, this makes any objective analysis difficult.

Interested in everyone's go-to reference tracks, preferably across multiple genres?
 

Dave Upton

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So it occurs to me that my system can sound anywhere from incredible to atrocious depending on the source material I feed it. I figure I'm not in the minority in that my music collection is a hodge-podge of digitized material collected over many years and of varying quality. Of course, this makes any objective analysis difficult.

Interested in everyone's go-to reference tracks, preferably across multiple genres?
I listen to mostly lossless music from my personal collection or from Qobuz.

Check out the album road houses and automobiles by Chris Jones, there are a couple of tracks in that album that I truly love for an audiophile demo, including No Sanctuary Here and Thank You RJ Reynolds.

Do you have a genre of music you like more than others? I can make some more specific recommendations once you tell me
 

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Much of the music produced today sound terrible on good systems. The songs are overly compressed and the bass comes out as square waves. Even artists who sounded good 10 years ago suddenly sound terrible on their latest recordings.
 

JohnRice

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So it occurs to me that my system can sound anywhere from incredible to atrocious depending on the source material I feed it. I figure I'm not in the minority in that my music collection is a hodge-podge of digitized material collected over many years and of varying quality. Of course, this makes any objective analysis difficult.

Interested in everyone's go-to reference tracks, preferably across multiple genres?
Most of my "show off" stuff is high res music from HDTracks. Of course, nobody ever comes to my house, so I'm just showing off to myself.

One of my favorites is Dream Theater's A Dramatic Turn of Events. There are several show off worthy pieces, but one that especially kicks your ass is Outcry.



For something that completely awesome in an entirely different way, here's a video from the recording HDTracks has of Kim Andre Arnesen's Magnificat, recorded in a cathedral, and the ambiance of the recording is just astounding.


If you're looking for HD remasters of some classic rock, Chicago Transit Authority, Supertramp's Crime of the Century, and Jethro Tull's Aqualung are all incredible.
 
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