2.4KW amp, anyone?

[Robh3606]

Lee is right on the money. I hope no one is talking about 0dbfs (full scale) music playing at 2.4 KW!!!

Hello Amir

Of course not but the bottom line is we are talking just peak SPL. So I could substitute in 600 watt amp and just back my max SPL down 6db. Drop it 3db and use a 1kw amp. If you do start pushing the power levels up with higher SPL levels you are going to end up with power compression issues from the drivers which will only get worse with more power and time. I agree you definaelty hear benefits having more watts for more headroom. I have quite a bit of headroom in my set-up, I could have more but I see it as pointless once you have enough power reserves to get the peak spl levels you want to acheive in your room.

Rob

 

[fas42]

I don't think people would have an issue with bigger amps producing a greater sense of ease. That's been readily apparent driving my Martin-Logans with the the 275 wpc cj tube amps. What has been an issue is that the larger power amps just don't sound as good as the lower powered amps. That came out years ago in comparing say the smaller Class A Bedini amps vs the large, same circuit design 100 wpc Bedini amps. Many thought the little ARC Classic 60 sounded much better than its bigger brothers and so on (of course on the right speakers). I think the same thing held true for the little 60 watt Jadis amps sounding better than the 200 or 500 watters. But...the bigger amps just have a greater sense of dynamic ease

Thanks for the comments so far, guys, it's been very helpful! Yes, I have noted the apparent problem that higher powered amps appear to have for people many times, it has been repeated over and over again that some of the "magic" , or musicality is lost as you up the horsepower. I believe part of the answer for that happening is that as you increase the ratings of the various components to deal with the power handling, everything physically increases in size and spacing from everything else, and the very manner of constructing a particular circuit topology alters. This allows more distortion behaviours to intrude, and poorer sound.

As my intent is to make an amp that can do both a sense of ease and be pleasant to the ear, I would ensure in such a large beast that the physical positioning of components was optimised. This was a philosophy that I followed with the DIY gainclone and certainly that paid dividends; it was capable of reaching clipping and thermal shutdown without losing sound quality.

As has been stated, the power in the real world can be easily used up. Take an 84dB sensitivity speaker, the seemingly enormous 2400 watts translates to a bit over 30dB power gain at 1 metre from the speaker, meaning 114dB, and then about 109dB at the listening position: not that spectacular really! This is only the level on a musical peak, average is probably around 103dB.

Mark, the HT box is pushing to get 20 watts a channel, but they are good watts, and most people here know the difference. I also have the 200 watt Perreaux, and when I first started playing around with it I had no trouble hearing the power supply start to collapse at only a bit more than decent sound levels. The HT played up once or twice before, but came good of its own accord: this time it seems more set in not co-operating, and the problem could be in one of the custom, do everything, chips. If not easily fixed, no point in continuing with it, it was only ever a test bed ....

Finally, the sound quality I talk of has been achieved with 20, 60 and 200 watts. It is not the oomph, it's how well it's been sorted out.

Frank

 

[mep]

I think that's a whole other debate and probably not entirely on topic.

I disagree. Any thread that deals with the benefits of having very high headroom should also be open to discussing if anything is given up by going to higher powered amps over their lowered powered brethren.

This used to be an issue in days gone by, and I for one am not sure if it’s still relevant with today’s amps. And having said that, I’m a fan of high powered amps for many reasons.

 

[fas42]

Of course not but the bottom line is we are talking just peak SPL. So I could substitute in 600 watt amp and just back my max SPL down 6db. Drop it 3db and use a 1kw amp. If you do start pushing the power levels up with higher SPL levels you are going to end up with power compression issues from the drivers which will only get worse with more power and time. I agree you definaelty hear benefits having more watts for more headroom. I have quite a bit of headroom in my set-up, I could have more but I see it as pointless once you have enough power reserves to get the peak spl levels you want to acheive in your room.

Rob

Rob, my experience has been over and over again that speaker drivers are quite amazing fellows. Provided you don't try and cook them with pure sine waves or badly clipping amps, they do a remarkably graceful job of handling high level transient signals. General audio chatter would tell you other, but I have yet to hear a driver cry uncle if I fed it clean power with a reasonable, musical, signal ...

Frank

 

[mauidan]

I don't think people would have an issue with bigger amps producing a greater sense of ease. That's been readily apparent driving my Martin-Logans with the the 275 wpc cj tube amps. What has been an issue is that the larger power amps just don't sound as good as the lower powered amps. That came out years ago in comparing say the smaller Class A Bedini amps vs the large, same circuit design 100 wpc Bedini amps. Many thought the little ARC Classic 60 sounded much better than its bigger brothers and so on (of course on the right speakers). I think the same thing held true for the little 60 watt Jadis amps sounding better than the 200 or 500 watters. But...the bigger amps just have a greater sense of dynamic ease.

Things have been slowly changing but there's still some magic--be it compromises that have to be made in winding output transformers and bandwidth, etc.

I remember HP (TAS) always saying it was easier to build a good small amp than a good big amp. Fewer output devises, simpler circuit design.

Currently, I have three amps in my listening room, SS-700 watts/ch, SS-200 watts/ch and Tube-25 watts/ch into my 4 ohm speakers. Lately, the 25 watt/ch amp has been getting most of the playing time.

 

[fas42]

I remember HP (TAS) always saying it was easier to build a good small amp than a good big amp. Fewer output devises, simpler circuit design.

Currently, I have three amps in my listening room, SS-700 watts/ch, SS-200 watts/ch and Tube-25 watts/ch into my 4 ohm speakers. Lately, the 25 watt/ch amp has been getting most of the playing time.

Yes, exactly what the "problem" is. Would you care to mention what the amps are (I note 2 on your profile)?

Frank

 

[mauidan]

Yes, exactly what the "problem" is.

There's no "problem." It's just a personal preference that could change at any time.

Would you care to mention what the amps are (I note 2 on your profile)?

Other than what's on my profile, no.

 

[Robh3606]

Rob, my experience has been over and over again that speaker drivers are quite amazing fellows.

Hello Frank

Yes but it's one thing to go through a thought experiment and quite another to actually do it in the real world. As amazing as they may be you can't get around the laws of physics. You simply can't dump unlimited power into drivers. They have thermal limits and physical limits such as x-max that you cannot get around. If you want THX level SPL readings or realistic peak levels on music you don't base you system around 84db speakers.

Rob

 

[fas42]

Yes but it's one thing to go through a thought experiment and quite another to actually do it in the real world. As amazing as they may be you can't get around the laws of physics. You simply can't dump unlimited power into drivers. They have thermal limits and physical limits such as x-max that you cannot get around. If you want THX level SPL readings or realistic peak levels on music you don't base you system around 84db speakers.

Rob, I agree with what you say: of course you don't try to put too much power into drivers, that's the the point about them handling transient, momentary spikes of high power, the peaks in crescendos in other words. As far as I was aware, x-max is only something to worry about with bass drivers, and some of the big boys here can soak up well above 2.4KW if appropriately boxed. Midrange and treble will just imitate light bulbs, and release their inner smoke .

As regards 84dB speakers, the point is that people have these for their qualities of reproduction, not to do HT, but still would like to get realistic levels of sound during music listening. Which won't happen if the power amp is not up to it. An example: MBL 101Es, the watermelon speakers, 82dB sensitivity, they handle 500 watts RMS, 2200 peak; and you don't want to use MBL's amps ...

Frank

 

[fas42]

Oh, by the way, I've been tossing around a couple of names for the unit: favourites at the moment are either "Krill" or "Mork Levinson", engraved on perhaps some fancy and appropriate metalwork. Will that help anyone decide ...??

Frank

 

[mep]

Oh, by the way, I've been tossing around a couple of names for the unit: favourites at the moment are either "Krill" or "Mork Levinson", engraved on perhaps some fancy and appropriate metalwork. Will that help anyone decide ...??

Frank

Decide on what?

 

[fas42]

As I mentioned in the first post, whether it would worth my while pursuing the project. It would be an interesting exercise, but it is not really worth doing just for me alone, I don't have such inefficient speakers to drive nor the the need for such dynamic power. If others are interested in the results of such an effort then it may be worth making it work, and possibly going the extra step and putting it out as a product ...

Frank

 

[Tom Danley]

Amirm wrote
“Me, I found value in going up to 500 watts with a high efficiency design. Without it, likely would need another 50% to 100% to match the same. I was so surprised to see an improvement over beefy amps of somewhat lower power. So count me converted on part of this argument .”

Hi amirm,
Me too.
For me this happened when I had a chance to be in an official ABX listening test of a number of amplifiers. I brought in my trusty Threshold stasis as my known reference and used speakers I had designed at work and had at home as well.

There was plenty of time and I went through a number of my reference CD’s to find a few passages that brought out the differences best and then went to “without knowledge” listening. At this point one could still hear some differences between them but they generally fell into two groups which I could reliably hear. What I heard were differences in the decay part of the sound which I have no explanation for (I used to build amplifiers too).

A funny and unexpected thing also happened which is why I am writing, in comparing the various pro-amps to my Threshold, I found that one group and it were indistinguishable except the Threshold began to sound “less dynamic” as I increased the level. AS the Thresholds VU led scale showed the peaks were -20dB or so down, I was puzzled. Connecting an oscilloscope to the output revealed the truth.

At a point WAY below one could hear it as a “flaw”, at a point that indicator showed peaks as 1/100th rated power, there was instantaneous voltage clipping.
To be very clear, this WAS NOT audible at all as a flaw or heaven forbid the familiar “clipping” the only clue was that compared to a much larger amplifier, the Threshold was somehow less dynamic above a modest level.

At that point, I switched to a larger pro-sound amplifier at home too. Currently my upper speakers (SH-50’s) are about 100dB 1w1m and I use an 800W/ch power amp on these above 80Hz.
With any commercial recording or movie soundtrack, this is more than enough headroom to never breathe hard but I can still reach instantaneous limiting with the fireworks recording.

Anyway, the big and unrealized advantage of having more power is that the short voltage clipping events reduce the dynamics long before it’s audible as a flaw. This can be seen (when present) by using an oscilloscope to examine the Voltage waveform going to the loudspeaker.

To be clear, just as a subwoofers job is to extend the response and that is not the same as “turning up the bass”, this IS NOT the same as “cranking it up” although a larger amplifier lets you do that too if your speakers are up to it.. This is about reproducing the peaks (in the “good” recordings) which are often clipped off much more often than people realize.

Want to see different ways of looking at the dynamics or loudness of the same signal, try this on your favorite recordings.

http://orban.com/meter/

So far as making a “full push” hifi amp, why not.
Remember Pro sound amps take advantage of the fact that the peaks are at least 6-10dB over the average power, circuit breakers are intended to allow surges and have a time constant so having an amp that puts out several thousand watts from a 15 Amp outlet is not unreasonable..
Best,
Tom Danley
Danley Sound Labs

 

[Phelonious Ponk]

As I mentioned in the first post, whether it would worth my while pursuing the project. It would be an interesting exercise, but it is not really worth doing just for me alone, I don't have such inefficient speakers to drive nor the the need for such dynamic power. If others are interested in the results of such an effort then it may be worth making it work, and possibly going the extra step and putting it out as a product ...

Frank

If you're going to thoroughly document and post your design and build process, with pictures of your progress, I'm sure many of us would be very interested. If you're going to reveal no more than you have about your tweaks to the Phillips -- ie: vague generalities about superficial tweaks resulting in physics-defying results -- it will be worth much less to us than it would be to you alone.

Tim

 

[RogerD]

There is no substitute for horsepower.

 

[DonH50]

1 HP = 746 W

Just in case someone needed to know that...

 

[terryj]

You devil, you!! The tropical heat certainly does the damage, eh??

Terry/John is no particular fan of amps, so I don't know whether he would tune into the difference ...

Frank

It is Terry, what is with this terry/john stuff? Are you disputing me that it could have been john, and not me, you met?? Kinda OT, but it IS your thread so it's ok haha, I may have an idea who you are. Or not. I DO recall john telling me about some guy (dunno if it was you, but some clues are there) who auditioned some speakers using an atrocious Status Quo album..was that you frank?

But, if it was you, then you could not have met me eh. As I was not there when some guy auditioned speakers using an atrocious status quo album....

Did you come twice frank? How else (if it was you) could you have met me?

You are right tho, as far as 'sound' goes with amps I don't care one little bit. I think Tom has hit the nail fairly and squarely on the head, people clip their amps FAR more often than they realise. (which is why the extra caveat when comparing...and driven normally) Re-read Rogers descriptions on that matter.

And, it is often on music you'd least expect! On my bass drivers I have the old Phase Linear 700B, the one with meters. There was a bunch of guys here for the annual GTG one time, and we were cranking NIN. Yeah, the meter was moving, but nothing out of the ordinary.

Someone put on this chick singing norwegian wood (??). jazz stuff which I abhor so know nothing about, can't tell you who it is. Typical jazz instrumentation, upright bass etc.

Anyway, that was put on, and the few opening notes of this bass (nothing major), man, the needles hit the frickin pins!! SLAM.

We all were stunned...so here is a 350w/ch amp, on the bass drivers alone (96db sensitive, in active config) with the needles redlining on an upright bass jazz track. Just idling when cranking NIN.

People are happy with a 50 W amp running thru a passive network??? Well, no wonder they can 'hear differences between amps'.

So I am not against having enough power on tap frank!!

I have 600/ch on my subs, 350/ch on my bass drivers. 200/ch on my tens, 110/ch on my 6.5's, and fifty/ch on my tweeters. I'd imagine my tweeter is the least sensitive, (well, the subs actually)..the rest are over 96db. All active, amps connected directly to the drivers.

And, I have such a hodge podge of power because I only ever throw in whatever amp happens to be laying around, there is NO thought given to 'sound'...hence as I move up the amps get distributed according to the power requirements.

Does this mean we agree on something Fank?? haha, we are now audio buddies??

 

[fas42]

A funny and unexpected thing also happened which is why I am writing, in comparing the various pro-amps to my Threshold, I found that one group and it were indistinguishable except the Threshold began to sound “less dynamic” as I increased the level. AS the Thresholds VU led scale showed the peaks were -20dB or so down, I was puzzled. Connecting an oscilloscope to the output revealed the truth.

At a point WAY below one could hear it as a “flaw”, at a point that indicator showed peaks as 1/100th rated power, there was instantaneous voltage clipping.
To be very clear, this WAS NOT audible at all as a flaw or heaven forbid the familiar “clipping” the only clue was that compared to a much larger amplifier, the Threshold was somehow less dynamic above a modest level.

This is exactly the thing I've been talking about all the way through, something that I became aware of with the 200 watt Perreaux, well over 20 years ago: it was very easy to hear exactly where, and I shall use a dirty word, it started to distort, way down from the power that it should have been able to deliver. If I thought this amp, which I still have, was bad I got a shock when I went out and tested gear in hifi shops, they were far worse than the Perreaux! Uh oh, I thought, we've got a bit of a generic problem here.

So I'm impressed that you were able to monitor the actual misbehaviour of the Threshold, to see it actually feeding distortion to the speaker. Which is why I've been saying, over and over again, blame the amp, don't blame the speakers!

This is something I've been directly addressing, that's the IP I've mentioned, and why the miserable 20 watt HT fellow can do so well, it doesn't have this misbehaviour. Also, most likely why Steve and Jack's Lamm amps can do so well with the same "miserable" level of power ...

Frank

 

[mep]

Pictures of Matchstick Men and You...

 

[fas42]

If you're going to thoroughly document and post your design and build process, with pictures of your progress, I'm sure many of us would be very interested. If you're going to reveal no more than you have about your tweaks to the Phillips -- ie: vague generalities about superficial tweaks resulting in physics-defying results -- it will be worth much less to us than it would be to you alone.

Tim

If I'm hoping to commercialise it in some sense then I don't think that is going to be the brightest thing to do ...

Frank