Decades ago, I went to Circuit City, to look at AV receivers.
Except for the $1,200 AV receiver, all the other models were only rated for 8 Ohm speakers.
But every speaker in the store was either 6 Ohm rated or 4 Ohm rated.
Keep in mind that many 6 Ohm loudspeakers have minimum impedance of 4 Ohms.
That is often in the 20 to 30Hz region; and if it is a ported design, often at a frequency between the double impedance peaks of the ported design, and also, ported or not, often between 200 and 400 Hz.
Did those salesmen know about that?
Did the purchasing agent know about that?
Did the marketing person know about that?
Perhaps they did not care.
Where is Circuit City today? Gone.
Except for the $1,200 AV receiver, all the other models were only rated for 8 Ohm speakers.
But every speaker in the store was either 6 Ohm rated or 4 Ohm rated.
Keep in mind that many 6 Ohm loudspeakers have minimum impedance of 4 Ohms.
That is often in the 20 to 30Hz region; and if it is a ported design, often at a frequency between the double impedance peaks of the ported design, and also, ported or not, often between 200 and 400 Hz.
Did those salesmen know about that?
Did the purchasing agent know about that?
Did the marketing person know about that?
Perhaps they did not care.
Where is Circuit City today? Gone.
My phone pre was made by a now defunct company for radio stations. I bought it because it was the only one I could find with XLR outs.
The power amps are rated at 0.03% THD at 1dB below rated output which is for the 3 I own is variously 215W, 250W and 350W all into 8Ω from 20-20 000Hz (0.008 at 1kHz).
They were designed by Terry Clark (formerly founder and technical director of Klark Teknik) and Ian McCarthy who started EAR with Tim de Paravincini.
I found some independent tests for the biggest one which came out at 359W with 0.0058% at 1k. They were also the quietest amps they ever tested.
I gather now the Benchmark is a bit less noisy.
What I like about them is that I simply forget that they exist in my system.
The first amps I've owned which do that.
You might believe that but I hear it as being very obnoxious if it is above 1% while doing the Klippel double blind test, inaudible through my speakers at <0.5% though.
I assume you meant +/- 25VDC, not AC.
You have to remember that an audio (sine) wave is fluctuating between the + and - rails.
Thus, your total of +/- of 50 volts DC is what is totally available for the output transistors.
Not all of it is able to be used though, since voltage drops of the transistors, as well as design of the drivers, limiters, etc., limits things.
A reasonable guess generally speaking, is something around 75, maybe 80% of that before clipping, is sent to the speakers.
tube amp watts are real watts, solid state depends on the build and with class D it's the theoretical maximum, that is almost never possible in real live. Class A and AB tend to be at least close, but won't be able to give that all the time.
And like said, you mostly don't use the full power. Speakers tend to be 80 to 90dB efficent mostly (for hifi), and most listen between 60 and 90dB at home (90dB in a home is very loud, you can't speak anymore) so a few watt is mostly enough.
My amps are 32w (tubes AB), 20w (class D) and 45w (transistor class AB) and all are too powerfull for my home listening on my speakers that are between 86db and 92dB efficient. I had for a while 2 pairs of SET amps in consignation (owner was abroad for a long time) of 3.5 and 8w and even those were more than enough...
And i did dj on a new years party a few years ago for about 200 ppl with a pair of Kiplishhorns (105dB efficient) powered by a 2x 35W tube amp and a Tapped horn sub powered by a 1000w class D amp in a small hall, and that went loud... On the same, a decade ago i was at a reggae festival (Reggae Geel in Belgium) where a custom vintage tube soundsystem (Axis Valve A Tron) of 3kW overpowered a "40kW" class D powered line array...
And like said, you mostly don't use the full power. Speakers tend to be 80 to 90dB efficent mostly (for hifi), and most listen between 60 and 90dB at home (90dB in a home is very loud, you can't speak anymore) so a few watt is mostly enough.
My amps are 32w (tubes AB), 20w (class D) and 45w (transistor class AB) and all are too powerfull for my home listening on my speakers that are between 86db and 92dB efficient. I had for a while 2 pairs of SET amps in consignation (owner was abroad for a long time) of 3.5 and 8w and even those were more than enough...
And i did dj on a new years party a few years ago for about 200 ppl with a pair of Kiplishhorns (105dB efficient) powered by a 2x 35W tube amp and a Tapped horn sub powered by a 1000w class D amp in a small hall, and that went loud... On the same, a decade ago i was at a reggae festival (Reggae Geel in Belgium) where a custom vintage tube soundsystem (Axis Valve A Tron) of 3kW overpowered a "40kW" class D powered line array...
Efficient speakers make all the difference here, even if the 40kW of class D watts is more like 4K real ones. The bass/mid drivers in those modern line array elements are lucky to get to 93dB 1m/1W anymore. It used to be 100 was considered “PA level”, then 96, and it just keeps dropping. Give it another decade and PA drivers will be 85 if you’re lucky and home audio in the 60’s. With millions of class D watts behind them.
I don't agree with that either but that's not to say I don't like beefy amps, it's just I don't see how a continuous full power sinewave has anything to do with music.
Here's a bench test of several of the biggest professional amps produced, the LG6400, Crown IT8000, and Powersoft K6 and K10. If you scroll all the way to the bottom they do the full power duration test at 8, 4, and 2 ohms, all of them do quite well into 8ohms but at 4 and 2 ohms they all start reducing output after about 1sec.
http://diy.poweraudio.ro/albums/userpics/10001/BENCH_COMPARISON_TEST.pdf
I bet that did sound sweet... unlike the last time I heard some Klipsch horns. It was a party at a university residence where the DJ had 4 LaScalla Pros powered by a Bryston 4B flat out with no processing. It was stupid loud and painful, I couldn't stay in the room and I like loud music. Total shame.
If the tube system was spec'd the same way as the Class D amps powering the LA it probably would indeed be more powerful. In this case it's not about the speakers as they are all direct radiating, and magic isn't real so saying the valve system is only 3kw is as big a lie as saying the LA was 40kw.
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Hard to say, but perhaps a limiter circuit kicks in, to limit and protect both the amps and the speakers.
A lot of amp designs have such safety features built into them, it's nothing new.
Back in the mid-1970's I had a night job on the weekends being a DJ at a nearby bar.
Smallish place, the dancefloor area could handle 40-50 wiggling disco dancers.
I had to supply the equipment and music (records of course).
That place was rockin' and loud, and the dancefloor got packed on a Saturday night.
And all I had was my pair of Dual turntables (1219/1229) a Dynaco Stereo80 (40/40W)SS amp, a Newmark mixer, Koss PRO4AA headphones, and a pair of Advent "small" speakers up on the wall.
Never had a problem with that system, ever.
Smallish place, the dancefloor area could handle 40-50 wiggling disco dancers.
I had to supply the equipment and music (records of course).
That place was rockin' and loud, and the dancefloor got packed on a Saturday night.
And all I had was my pair of Dual turntables (1219/1229) a Dynaco Stereo80 (40/40W)SS amp, a Newmark mixer, Koss PRO4AA headphones, and a pair of Advent "small" speakers up on the wall.
Never had a problem with that system, ever.
Yes it's limiting circuits protecting the amplifier and yes this is nothing new, it's good design that keeps a show running. But it just goes to show.. these thing power some of the biggest concert sound systems on the planet and if those manufacturers, event producers, and system engineers don't think generating full power sinewaves indefinitely is required then why does anybody else.(EDM producers exempted)
For years... perhaps decades the audio industry has asked for more headroom from power amplifiers to better reproduce dynamic music, now we have it and all people complain about is how poor the new beasts are with sine waves.
For years... perhaps decades the audio industry has asked for more headroom from power amplifiers to better reproduce dynamic music, now we have it and all people complain about is how poor the new beasts are with sine waves.
Not to mistake my previous post about amp testing, I agree that testing with a low frequency sine wave is not music.
It's merely a simple test to determine IF the amp can handle a 60Hz tone for a few moments at least.
We all can agree that most of the power of any given amp is used for bass, right?
That takes a lot of current to produce, and if said amp can sustain it for even a few moments (at just below clipping levels) without breaking up, lagging and distorting, fine, it should certainly do well with music.
It's merely a simple test to determine IF the amp can handle a 60Hz tone for a few moments at least.
We all can agree that most of the power of any given amp is used for bass, right?
That takes a lot of current to produce, and if said amp can sustain it for even a few moments (at just below clipping levels) without breaking up, lagging and distorting, fine, it should certainly do well with music.
People have certainly used and enjoyed music for a a long time through audio amplifiers that are built like arc welders.. present company included, but the cost of building an amp to do that becomes more and more prohibitive as output power levels increase.
There is value in a sine test for sure but I just think there may be a little too much emphasis placed on it by some. Of course I have to recognize that there are a wide range of music genres and indeed some of them do contain a lot of sustained sine or synth tones, so there are applications where meeting this spec is much more important.
In my early days in the audio biz I was dismayed to discover how badly some seemingly good power amps were at performing under a 4 ohm load. It's become a bit of a benchmark for amp performance for me so I was surprised to see some of those expensive touring amps buckle at lower impedances in that bench test I linked. I guess it just goes to show that there are limits even with new technology when minimum size and weight are high on the priority list.
There is value in a sine test for sure but I just think there may be a little too much emphasis placed on it by some. Of course I have to recognize that there are a wide range of music genres and indeed some of them do contain a lot of sustained sine or synth tones, so there are applications where meeting this spec is much more important.
In my early days in the audio biz I was dismayed to discover how badly some seemingly good power amps were at performing under a 4 ohm load. It's become a bit of a benchmark for amp performance for me so I was surprised to see some of those expensive touring amps buckle at lower impedances in that bench test I linked. I guess it just goes to show that there are limits even with new technology when minimum size and weight are high on the priority list.
McIntosh MC2300, 300W/ch brute amp. - used by rock bands and outdoor concerts a lot.
Old school design, 128 pounds of metal.
I overhauled one about 2 years back, and believe me, that one can be classified as an arc welder.
Old school design, 128 pounds of metal.
I overhauled one about 2 years back, and believe me, that one can be classified as an arc welder.
What a SS amp does into 4 Ω is an important clue. If it can't make roughly twice the power it can into 8 Ω, it is an indication of corner cutting in the PSU. Tubes or SS the PSU is the foundation upon which the entire thing rests. Crappy PSU = crappy amp!
While absolutely necessary, a good PSU is not, by itself, sufficient. A good PSU provides the opportunity to have a good amp. Opportunities are seized and (unfortunately) squandered.
While absolutely necessary, a good PSU is not, by itself, sufficient. A good PSU provides the opportunity to have a good amp. Opportunities are seized and (unfortunately) squandered.
Well, the guy builds his own amplifiers and speakers and other equipment (dub preamplifiers, phono stages, ...) and is very known for his high quality high power tube amps. He rates them at clean sounding level, but they can be pushed a bit further into distortion if you want. He is the guy for amps for this kind of sound systems and makes a living out of it these days. Paul Axis | Facebook
The picture is his actual own build 1.5kW bass cabinet amp with a whole leap of 807 power tubes next to his wife for size reference (like he said it). He did not have this amp at that time yet and used several smaller ones for his basscabinets.
