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In Reply to: RE: Quad ESL 63 impedance curve: not as bad as we thought? posted by banpuku on March 29, 2016 at 07:14:01
SET and Quads not working are probably folklore more than reality.
For me SET would not work because of limited SPL. But if one can live with lower maximum SPL, the typical Quad owner, the SET will work fine. I know plenty of people using SET and they are quite happy with the combo.
When I take Quads to shows we always use low output amps typically around 20 watts. At CAF last summer we had a large room, 24' X 20', running original Quads and the Miyajima 20 watt OTL. Filled the room with sound and played plenty loud enough for everyone.
8-10 watts of power should get the Quad to 88dB without clipping.
Follow Ups:
88dB max FAST RMS I hope... 88dB peaks are the same at conversational speech levels. Just me talking at normal levels on the left (87dBPeak, 64dBA Average Level) and on the right, me raising my voice to just a moderately louder level and banging my fingers on my desk to simulate music dynamics (this is not Loud). The mic is about 1 meters away in my small office.
In the two examples, the average level goes up about 15dB (LAeq/Lceq/Phon) The Fast weighted (think VU meter) max levels go up 16dB but the peak level goes up over 22dB!
To play music with an average level of 88dBC might take a watt of power - and to capture the peaks in this simple example, the Amp needs to swing a wider voltage (about 10x the voltage) to not clip the signal - and remember this is C-weighted -3dB at 50Hz and 10kHz
2.8Volts is a watt into 8 ohms so the amp needs to swing 28 volts before clipping. Can your SET swing +/- 28 volts?
It's just that most the time SET owners don't realise their amps are clipping when they are. Or otherwise mistake the distortions of clipping as something pleasant.
I love Real measurements!
"The hardest thing of all is to find a black cat in a dark room, especially if there is no cat" - Confucius
Agreed.
Some users will never push the speakers beyond 88dBC peaks. While this is not loud enough for me for many Quads users that will be fine.
Under these conditions a few watts will get the job done.
I would venture that EVERY listener will push their speakers well beyond 88dB peaks - infact I would say that every listener here will push there system well over 100dB. Especially with high quality signals.
Now granted it is very hard to find recorded sources that hold a 15dB or greater crest factor (Peak to RMS Ratio) and they have been produced. A lot of popular recordings may only have a very unrealistic 8-10dB greast factor.
But as you can see from my measurements even my mild simulation had 18dB crest factor.
"The hardest thing of all is to find a black cat in a dark room, especially if there is no cat" - Confucius
I would venture the typical Quad owner never gets close to those kind of output levels. I would not be one of them but that is the case for most folks that own Quads.
One of the nice things about a Quad is it can sound amazingly lifelike, 3-dimensional, etc. with levels at 60-70dB output, average. It does not fall apart at extremely low levels and does not need to be pushed to loud levels to open up. The reason why many people like them versus other speakers. Low level resolution is outstanding.
And you wonder where the bass goes at 60 to 70 dB. With the human ears' bass response at low levels rolled off significantly even a flat speaker sounds rolled off badly at these levels. No orchestra will sound lifelike at those levels.
...and does not need to be pushed to loud levels to open up. The reason why many people like them versus other speakers. Low level resolution is outstanding.
Agreed. I suppose 100db+ might be fun every now and again to shock a visitor. I would be exhausted after focused listening to music at those sorts of levels for more than a few minutes. This is not typical of listeners here I gather.
A healthy pair of original Quads will play louder than many people think can (obviously not Wilson or Magneplanar QR levels). I will bring my Radio Shack SPL meter with me the next time I sit down with my Quads. I am curious to see what average and peak levels I measure.
FYI: I turned on the TV as I typed this and set it for what I consider normal listening level. I am measuring 64-67db average, 70db peak (fast response, C weighting) at my ears.
100+ dB peaks are a function of the waveform and not audible - I go to my local Jazz club and measure a piano at 15 ft away, and you get peaks over 105dB, a snare hit pops 116dB the average level (LOUDNESS) is only about 85-90 dBC - they aren't even trying to play loud - the place seats 40.
Sure you can lower the volume in playback but it is not real. And how many of you have your loudness compensation button pushed in.
Granted - the mastering engineer/producer will not allow a real life 25-30dB crest factor to go into a music recording even if he has 16 or 24 bits to play with.
Why? one reason is to prevent likely amplifier clipping when played back on typical playback equipment.
Of course the main reason is the most folks would think the recording is "broken" not playing loud enough.
"The hardest thing of all is to find a black cat in a dark room, especially if there is no cat" - Confucius
The crest factor for large scale orchestral works reaches into the 30 db range. Which is why NAD class H amps work so well despite lowish RMS ratings.
While my listening preference is for higher peak volumes I don't actually play average volumes much over 80 db. The loudest passages are played at 90-94 db average but they peak at 105-115 db.
I ran bass sweeps when a pop fan friend was over and was doing 90-95 db SPL at 25 and 20 hz and he asked "what is THAT?" so I told him. It was only moderately loud subjectively, but outside of large hall sub harmonics short bass drum whacks and organ pedals we don't get to hear that bottom octave often. In pop music it is only in synth hip hop (Erika Badu) and electronica (Anderson) that those show up any sub 30 hz content.
My music teacher's quads with the 40 watt Macs did not do orchestra very convincingly even with his KEF 9" oval subwoofer. In his tiny listening room you would be surprised how loud the quad could go but the setup did not do peak volumes at realistic orchestral levels. While this did marvelous string quartets and vocals the orchestral and piano peaks were always decidedly clipped and bass dynamics really limited if not just plain MIA. The alternative was to play music at low volume so that peaks don't go beyond mid 90s db.
Instruments just don't sound like themselves at the wrong volume. You obviously hear the clarinet having the $&%# blown out of it but it barely passes mezzo forte in the quad system. The trumpet or violin played hard lose their smoothness and get gritty and are ear shearing in real life in the front orchestra seats. Nothing like it in restricted volume listening. Brings you back to row 53 deep under the balcony. Seats you so don't want to sit in that you consider not going even with free tickets.
For the front orchestra listener there has to be a match between the volume at which the instruments or voices sound strained and those indications of strain in tonal structure and texture. Not a problem for a mid balcony listener where the strained sound occurs at moderate levels. If you listen to chamber music is living rooms and small venues then you are aware that they were written with full scale orchestral dynamics in mind that are achieved readily in the small space they were traditionally performed in. One of my pet peeves is the original instrument movement insisting on using chamber orchestra ensembles in gigantic modern halls built for a 200 member orchestra. Why don't they also insist on playing these ensembles and instruments in the 300-500 seat halls in which they were originally performed, or having a piano quartet performed in a salon of 25X50 ft seating 40 or 50 people.
For people growing up with real instruments at close quarters then listening to live performances at the front orchestra seats a Quad based system will just not match up with their experience of live music. Fortunately, recordings are made from a much closer perspective so you can play the back with a row 4 -row 7 volume levels that DO reach 115 db peaks (a few milliseconds) on large scale works from Stravinsky or Mahler. That being while preserving the spatial spread of the orchestra in front of you going 20+ feet in either direction. .
Max Fast and Average levels
"The hardest thing of all is to find a black cat in a dark room, especially if there is no cat" - Confucius
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