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How true? Class D amps can't sustain their maximum spec'd power

MakeMineVinyl

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Yeah the full size Altec horns are large'ish. I traded a set of full size metallic green Altec horns for a mid sized flat black Altec horn assembly and used them on top of the speaker cabinets at about 4 feet in height at the horn throat with the tweets right below. It sounded snappy, dynamic and clean.
VOTT Decal.jpg
 

Doodski

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@MakeMineVinyl so how about a pic of this efficient tube (Maybe a hybrid amplification and transducer arrangement.) system of yours. :D I'm super curious to see what you have formulated together. With the efficiency you are quoting this has to be intriguing.
 

MakeMineVinyl

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The multicellular Altec horns are where things get real -- I can't afford a pair, though.
I still love Gary Kaufman's A5s... some of the best loudspeakers I've heard that aren't (weren't) insanely expensive.



View attachment 151490
I remember watching the guy at the factory soldering those horns together with a huge soldering iron. :)
 

mhardy6647

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I still see AL Voice of the Theatre and other models coming up @ Canuck Audio Mart. (The US Audio Mart Canadian equivalent.)
They are not inexpensive.
Nor were my Frankenaltecs -- although the fact that the 515B 'woofers' are on loan from a local guru does help.
 

Doodski

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They are not inexpensive.
Nor were my Frankenaltecs -- although the fact that the 515B 'woofers' are on loan from a local guru does help.
I had these. They triggered the entire horn midrange drivers endeavor that I went upon. I traded the AL woofs and full size horn assembly stuff for 2 mid size AL horns and compression drivers and put as much power behind everything as I could find on the shelf at the time.
 

Rottmannash

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No argument just trying to understand how the advertised numbers relate to real world performance. From my understanding it sounds like a 400 watt Class D is not really comparable to a 400 watt Class AB as the class AB will have more headroom for transient peaks so more like a 400 watt Class D is comparable to a 275 watt Class AB for playing music.
Nope
 

JohnYang1997

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Yes I understand .... but how do you think about amp headroom? If there are 2 400 watt amps, one that had 0.25 dB of headroom and one with 3 dB of headroom do you consider them the same?
If one has more "headroom" then it's not the lower power number amp. It's the higher number with no headroom number amp. Basically it's a 420W amp and a 700W amp.

There are discussions about thermal designs but that's not my point was.
 
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Doodski

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Yes I understand .... but how do you think about amp headroom? If there are 2 400 watt amps, one that has 0.25 dB of headroom and one with 3 dB of headroom do you consider them the same?
I look first at the Watts/dollar or such. Class D has so much of that the numbers make for a good case.
 

Rottmannash

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I cranked up my system (Schitt Freya+ > Purifi > F208's) the other day with some well recorded hard rock to the point it was painful and scary- no distortion, just brutally loud. I could only tolerate it for about 20 seconds and the amp wasn't even warm. I can't imagine needing any more power.
 

DonH56

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I've never measured my vacuum tube 2 1/2 watt amplifier for transient power, but I bet it would be awesome. I know it plays for something like 15 seconds after I cut plate power. :D

I still remember the SoundDesign all-in-one el-cheapo system I had to repair way back when that was rated something like "1000 W instantaneous dynamic music power". That from a 2N3904/2N3906 output stage. Yes, "output", not "driver" stage... :p Might have done it for a millisecond before the fuse blew if you shorted the output. But I sort of doubt it.
 

levimax

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If one has more "headroom" then it's not the lower power number amp. It's the higher number with no headroom number amp. Basically it's a 420W amp and a 700W amp.

There are discussions about thermal designs but that's not my point was.

When ever @amirm reviews a power amp he shows "continuous power" and "peak power". Usually companies advertise "continuous power" and I think that is what most consumer expect when a company says they are selling a 400 watt amp. Looking at Amir's "peak power" measurements there are large differences in the amount of headroom different amps rated at the same continuous can power provide. I am not sure how much this matters but I am sure that all things being equal the amp with more headroom would be preferred.
 

JohnYang1997

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When ever @amirm reviews a power amp he shows "continuous power" and "peak power". Usually companies advertise "continuous power" and I think that is what most consumer expect when a company says they are selling a 400 watt amp. Looking at Amir's "peak power" measurements there are large differences in the amount of headroom different amps rated at the same continuous can power provide. I am not sure how much this matters but I am sure that all things being equal the amp with more headroom would be preferred.
No. Manufacturers should sepcify 1% THD power not at the tick which Amir uses.

Now you are getting into the clipping behavior, the 0.1% 1% 10% distortion rabbit hole. There's no correlation in the amp either the amp is class D or other. It's all the other design choices.

When stick to 1% distortion power, a 400W amp is a 400W amp.
 

levimax

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No. Manufacturers should sepcify 1% THD power not at the tick which Amir uses.

Now you are getting into the clipping behavior, the 0.1% 1% 10% distortion rabbit hole. There's no correlation in the amp either the amp is class D or other. It's all the other design choices.

When stick to 1% distortion power, a 400W amp is a 400W amp.

OK I think that is a great way to look at it both practically and for the consumer.... now we just need everyone to agree that this is the new standard :).
 

MakeMineVinyl

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I still remember the SoundDesign all-in-one el-cheapo system I had to repair way back when that was rated something like "1000 W instantaneous dynamic music power". That from a 2N3904/2N3906 output stage. Yes, "output", not "driver" stage... :p Might have done it for a millisecond before the fuse blew if you shorted the output. But I sort of doubt it.
Does that mean that if I parallel two 2N3904/2N3906 transistor pairs I can get 2000 watts? :eek:
 
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