Amp design.

[zumbo]

If your speaker impedance drops to 1 ohm and the source(music/movie) you play requires 500W at that point but your amp adjust the rail voltage so as not to deliver more than 200W then you end up starving your speakers for that short duration for the sake of limiting the distortion to that 0.005% from the otherwise much higher distortion of say 0.08%. That's why for peace of mind some people prefer the 300/500W amp because they know they cannot hear the 0.08% distortion but they sure can detect a 4 dB increase in volume.

Now you can always get the MC-602 and keep all those high dynamic transients even with the autoformer output interface. For the best of both worlds, MC-602 is the answer.

But, isn't the 500W too much? I know many of you will say no. But, they don't make my speakers anymore. I have pushed many speakers above their limit with clean power. The sound remains clean until the tweeters can't take anymore, then sleepy time. I am a fan of the volume knob, and I have a high threshold for pain.

 

[PENG]

Everyone knows, as the volume knob goes up, the music looses it's detail. Why? All things mentioned. But, if the amp maintains it's composure, the detail remains as well. This, I believe, is the reason for the value.

Not necessarily, if the amp is putting out 500W into 4 ohms or say 800W into 2 ohms at 1.6X0.007=0.012% distortion (your theory of double distortion for double the power, I think it would be much higher), most people would think that the amp is still keeping it's composure. In this case, it is more likely that the speakers will not be able to keep their composure and begin to sound harsh.

A mid level 300/500 power amp costs 2 to 3K. A 3K per pair speakers should be able to handle 500W transients without losing it's composure but it will likely have trouble handling 500W continuous power, even at 0% THD.

 

[PENG]

But, isn't the 500W too much? I know many of you will say no. But, they don't make my speakers anymore. I have pushed many speakers above their limit with clean power. The sound remains clean until the tweeters can't take anymore, then sleepy time. I am a fan of the volume knob, and I have a high threshold for pain.

Depends on what and how loud you listen to, size and acoustic of your room. hifi will probably tell you 500W won't be not too much. I don't listen loud but I listen to enough classical music that has transients high enough that I cannot rule out getting the 602 if I go the McIntosh route. For continuous power, 200W is enough for me. Clean dynamic/transient power is why I want much more.

 

[zumbo]

Depends on what and how loud you listen to, size and acoustic of your room. hifi will probably tell you 500W won't be not too much. I don't listen loud but I listen to enough classical music that has transients high enough that I cannot rule out getting the 602 if I go the McIntosh route. For continuous power, 200W is enough for me. Clean dynamic/transient power is why I want much more.

My Adcom 7605 claims 175W @ 4ohm. I use every bit of it. The peak indicators light up, and the clarity fades. I wouldn't want it any louder, and I don't think my speakers can take any more. Rated 180W max. However, I feel that if I put a 200W@8hm amp that makes it 330W@4ohm, it will be clean above the power needed. The hand will get happy with the clean power, and as I said, sleepy time for the tweets. On the other hand, an amp than delivers 200W without fatigue seems perfect.

This is not only a discussion for my certain situation, but one that I consider important at any power level.

 

[highfihoney]

But, isn't the 500W too much? I know many of you will say no. But, they don't make my speakers anymore. I have pushed many speakers above their limit with clean power. The sound remains clean until the tweeters can't take anymore, then sleepy time. I am a fan of the volume knob, and I have a high threshold for pain.

500 watts isnt too much,ive always said on this site that as long as an amp can truly hold its spec while being driven hard speakers can easily be pushed way past their rated limits.

I like the volume knob too,my speakers are rated for no more than 300 watts continuous & im running mc1201 1,200 watt monoblocks & i drive the crap out of them with the power levels reaching above 900 watts continuous & short term peaks well over 1,200 watts,at these levels the power guard feature rarely comes into play but when it does its for a split second & i cant hear it.

Ive owned this set of speakers for 3 years now & the minimum they have been driven with was an mc500 500 wpc amp,for the last 2 years its been 1200 watts & all without even damaging a single tweeter.

I try not to talk about my krell stuf in a bad way because i like the amp but i wouldnt dream of pushing my KSA 150 through them at its hardest & if i did i'd have 44 blown tweeters.

 

[Yamahaluver]

You didn't vote for this design.

What design are we talking about?

 

[zumbo]

What design are we talking about?

The point here is being cool under pressure, that means delive high current with a huge transformer and caps, and be distortion less at the same time, thats the attribute of a good amp.

This goes along with the second option, but you voted for the first.

 

[mtrycrafts]

But again, if the amp resists this behavior? What then? It maintains it's composure? Delivers the power needed? At a well respected, and acurate distortion spec?

If it delivers the needed power at that lower impedance, then that is all the amp that is needed, just don't count on it delivering more, what the speakers may really demand. Again, it is a very limiting amp.

 

[mtrycrafts]

That is the point entirely. Doesn't matter, if the amp doesn't see the drop. This is why I think other designs are flawed. We all know the speaker doesn't maintain it's ohm spec. Any speaker.

I think you are missing the forest from the trees

The amp does see the impedance drop and is limited in output. The speaker's sensitivity would dictate more power as impedance drops to maintain the correct spl. It cannot, so the speaker's response will be non linear with power.

 

[zumbo]

If it delivers the needed power at that lower impedance, then that is all the amp that is needed, just don't count on it delivering more, what the speakers may really demand. Again, it is a very limiting amp.

I think you are missing the forest from the trees

The amp does see the impedance drop and is limited in output. The speaker's sensitivity would dictate more power as impedance drops to maintain the correct spl. It cannot, so the speaker's response will be non linear with power.

If this is fact, then the resale value would be squat.

The distortion numbers have been thrown around like it is no big deal, but if you look at the percentage, it is a big deal.

Look at the Bryston specs.
< 0.005% 20Hz to 20kHz at 300 watts into 8 W
< 0.007% 20Hz to 20kHz at 500 watts into 4 W

66.7% of 300W added to 300W will give you the 500W.
40% of .005 added to .005 will give you .007

There is a 40% increase in distortion. That's big. I know we can't hear .007, but the speaker can. If a speaker goes above 20kHz, we can't hear it. But, the speaker can. So, if the speaker can hear the 40% increase in distortion, the SQ will most certainly be effected.

Another way to put this whole thing.

Two choices. An amp that doubles it's power to get 200W. Or an amp that is 200W no matter what the load. I think there is no contest here.

This is not about the cost. This is about the best way to get 200W to a 4ohm speaker. Or, if 500W is needed, then the best way to get 500W to a 4ohm speaker. I still say the amp that does it no matter what the load. Distortion remains the same at peak of any ohm load. Amp remains cool. You are certain of what is getting to you speakers.

 

[Nuglets]

I think this has already been mentioned but it seems like the Mac gear has longevity in mind. They keep the maximum power output constant regardless of impedance which will make the amplifier last longer because as the impedance drops most amps will output more and more power but at the expense of generating a lot more heat, which we all know is the number one killer of electronics.

Also, like Zumbo said, we may not be able to detect that 40% increase in distortion but our speakers can and from what I understand, distortion will reduce the life of your speakers. I think it comes down to getting something that you will not have to replace any time soon. If you get a Mac amp with the amount of power to suit your needs(like HiFi's 1200W monoblock ) you can count on it being able to deliver that amount of power at any impedance, lasting for a long time, as well as keeping the distortion low at any impedance which should help protect the speakers. It seems like mac has many products to choose from so most people should be able to find an amp that delivers the amount of power they require so I can't see running into any problems because it doesn't double its maximum when impedance drops. I don't think any speaker would be demanding more than 1200W in a normal home audio setting so considering that amp doesn't double to a 2400W maximum when the impedance halves shouldn't be much of an issue, right? That's what I'm getting out if this...

 

[Nuglets]

I think you are missing the forest from the trees

The amp does see the impedance drop and is limited in output. The speaker's sensitivity would dictate more power as impedance drops to maintain the correct spl. It cannot, so the speaker's response will be non linear with power.

That is if you get an amplifier that doesn't suit your needs. Like I said in my above post, take HiFi's 1200W monoblock for example, I don't think any speaker is going to demand more than that amp can output no matter what the impedance drops to unless you are doing a test to see how fast you can lose your hearing when listening at EXTREMELY high volume levels.

Also, I'm not sure but I'm guessing that the amp DOES see the changes in impedance and increases the power much like any other amp but is limited to a maximum value that it will not exceed so you must get the right amp for your specific setup.

 

[highfihoney]

Too much emphasis is being put on the rail voltage being limited,the only time this happens is when the distortion level reaches 0.005% & then it only takes 1/1,000th of a second to correct the distortion back to the standard.

When the rail voltage is adjusted the effect is visual not audible,the amp tells you when its doing this,keep in mind that you need to be pushing the speaker way harder than with a krell amp (used as example only) to make this happen ,when the adjustments happen you loose no output from the amp & the sound never changes nor do the spl's & no impact is lost.

When the power guard does its job the results can be compared directly against output using the output meters on the amp,ive yet to hear a difference but just incase im going to measure spl's at the same time the power guard comes into action.

Results to follow.

 

[PENG]

Also, like Zumbo said, we may not be able to detect that 40% increase in distortion but our speakers can and from what I understand, distortion will reduce the life of your speakers.

The distortion spec for the $20,000 per pair B&W800D is:

Harmonic Distortion 2nd and 3rd harmonics (90dB, 1m)
<1% 45Hz - 100kHz
<0.5% 80Hz - 100kHz

So just the 2nd and 3rd harmonics are many times higher than that of most $2,000 solid state amplifiers. Most $2,000 per pair speakers won't even give you any distortion figures. The worry about "the speaker can hear 0.007% THD" is moot. Besides, look at Mc's tube amp's distortion specs and are you going to worry about them being too high and shorten the life of your speakers as well? I am sure my Veritas will love to be driven by one of those MC2102 and take the abuse of its 0.5% THD any day over my 0.004% THD solid state amp. I guess we both love the Mc amps, but not for exactly the same reasons.

 

[mtrycrafts]

The distortion spec for the $20,000 per pair B&W800D is:

Harmonic Distortion 2nd and 3rd harmonics (90dB, 1m)
<1% 45Hz - 100kHz
<0.5% 80Hz - 100kHz

That is at 1 watt. I'd like to see their THD at, say 10 watts, 100 watts.
I bet it isn't pretty.
Besides, distortion is juts another signal to the speaker, non destructive, unlike clipping can be.

 

[zumbo]

The distortion spec for the $20,000 per pair B&W800D is:

Harmonic Distortion 2nd and 3rd harmonics (90dB, 1m)
<1% 45Hz - 100kHz
<0.5% 80Hz - 100kHz

So just the 2nd and 3rd harmonics are many times higher than that of most $2,000 solid state amplifiers. Most $2,000 per pair speakers won't even give you any distortion figures. The worry about "the speaker can hear 0.007% THD" is moot. Besides, look at Mc's tube amp's distortion specs and are you going to worry about them being too high and shorten the life of your speakers as well? I am sure my Veritas will love to be driven by one of those MC2102 and take the abuse of its 0.5% THD any day over my 0.004% THD solid state amp. I guess we both love the Mc amps, but not for exactly the same reasons.

Distortion is just part of the whole picture. The question isn't which amp is a better design based on distortion? The question is which amp is a better design? The whole picture. I think we have both made our points, and both have merit.

 

[zumbo]

Besides, distortion is juts another signal to the speaker, non destructive, unlike clipping can be.

Ahha! Clipping. An amp that resists ohm load resists this as well.

Like I said, this is not all about distortion.

 

[mtrycrafts]

Not audible to human hearing? Yes. But, it has to play a part in SQ. Reliability. Heat. Speaker health. And, many other variables not being considered.

How can it be part of SQ if it is not audible? And, the more complex the music, the higher the THD needs to be for audibility. I think you are trying too hard to defend something not defendable.

 

[Nuglets]

The worry about "the speaker can hear 0.007% THD" is moot. Besides, look at Mc's tube amp's distortion specs and are you going to worry about them being too high and shorten the life of your speakers as well?

Actually I'm not worried about any distortion hurting my speakers and I don't even know what the THD value is on my amp. I was stating a point that I've read in the past that distortion is the main reason for driver failure which gave me the impression that it wasn't limited to clipping, but any kind of distortion. Again, that is just based on something I've read in the past and don't really know much about so by all means correct me if I'm wrong.

 

[Nuglets]

Besides, distortion is juts another signal to the speaker, non destructive, unlike clipping can be.

I guess that makes sense considering somebody I know has a Marshall stack setup from the 50's for his guitar and it's still perfectly fine even with a bunch of distortion from effect pedals.