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Why do you need a very powerful amp?

Discussion in 'audio' started by mandryka, May 20, 2019.

  1. martin clark

    martin clark pinko bodger


    Oh, that's the whole joke by the way: 'everyone says' ESLs don't do bass, and that's true if&only if your expectation of 'bass' is re-arranging the furniture to dull loud thumping sounds.
    Once you get over such delusions, you might find ESLs of any kind can do attack, and dynamic range, and the whole note envelope top-to-bottom like nothing else - just no sash-rattling. A more cerebral pleasure, for sure.

    (Anyway - Swamp Thing took them home with him then, nr a decade ago. And now we both have bigger Quads as well.)
  2. MattSPL

    MattSPL pfm Member

    Interesting. What would be the lower cutoff frequency in the bass of the Quads?
  3. sq225917

    sq225917 Bit of this, bit of that

    You cant beat quads, but even the biggins need a couple of 12" subs up em to portray the whole note. Ask misterdog, he runs 989s us and a 12" dipole and 150l cabled 12" dual sub setup. The bandwidth is remarkable
    MattSPL likes this.
  4. martin clark

    martin clark pinko bodger

    ESL57s have a bump c 90hz which is deliberate to offset their limited dimensions. After which they roll-off fast, and done by c 60Hz (but that's no impediment to great bass quality)

    989s and sim/later in room get down to v low30s quite easily. It's a surprise to many. I can run my old Steinberger Wav4 Upright bass through ' em and want for nothing in the bottom octave.
    MattSPL likes this.
  5. chartz

    chartz pfm Member

    Well my OTA ‘57s do make my furniture rattle a little and I can certainly feel that in my armchair which vibrates accordingly.
    MattSPL likes this.
  6. MattSPL

    MattSPL pfm Member

    I’d definitely need to run subs, but to be honest most speakers need subs IMO. If I can hear a bass note fade through fault of the speakers, it drives me nuts.
  7. George J

    George J Herefordshire member

    It is odd, because if the normal published performance figures for the original ESL really reflected what you were going to hear from the type, then you would expect that the pipe organ would be a caricature of what they really do sound like in real life. In my experience the ESL not only lets you hear the normal bass 16 foot "C," but easily shows when this is doubled by the 32 foot "C."

    In modern [A at 440 Hertz] tuning this gives pitches for the 16 foot bass "C" of approximately 16.5 and 33 Hertz for the 32 foot rank. I am not saying that the 32 foot "C" on the ESLis as impressive as standing in the south aisle of Hereford Cathedral by the 32 foot pipes, but from the naive the proportion of pedal notes compared to the rest of the organ is very much credibly presented by the ESL in a seamless progression.

    This is not trouser flapping bass, but it is well focussed and pitched. It is not trouser flapping in real life either.

    Best wishes from George

    Note piches:

  8. martin clark

    martin clark pinko bodger

    'need subs' is only about personal preference IME - like so much else in this pastime : )

    (To be clear - not my choice, I can get adequate measure of a low-B c 27hz as it is ; and I'd look to the recording before upsetting my neighbours...)
    Wilson likes this.
  9. MattSPL

    MattSPL pfm Member

    True. It’s a bit of OCD I have where I just can’t ignore missing bass. It stands out like a sore thumb when I listen to music. Don’t get me wrong, it’s as much about quality and the right quantity.
    Which leads back to Powerful amp question. A Krell integrated rated at 200w/ch vs a Krell fpb rated at 200w/ch, same figures, but the power amp is miles ahead in terms of bass power and control.
  10. John Phillips

    John Phillips pfm Member

    I haven't measured the draw-away curve in my room as you have. I think I should try that too.

    Floyd Toole in the 3rd edition of his "Sound Reproduction: … " book overlays draw-away curves from several sources for different (not line source) loudspeakers in domestic living rooms (fig. 10.8). The slopes range from -2.5 dB to -3.5 dB per doubling over 0.3 to about 5 metres. He notes (section 10.4) that differently treated rooms might fall outside the range but expresses surprise that loudspeakers with different directivities give such similar results.

    The difficulty is, of course, to not over-generalize from sources such as this. And the question of what real rooms do for SPLs as a baseline, as you point out, is one I have not found enough sources for.

    Uncertainties aside, however, I think it's quite easy to underestimate how good even moderately low power amplifiers work in real world situations if they have the ability to properly drive loudspeakers having low impedance / high phase angle points on their impedance curves.
    cooky1257 likes this.
  11. cooky1257

    cooky1257 pfm Member

    Indeed John, the rough guide is back of a fag packet stuff that seems to hold up reasonably well but given all the other variables its probably of very limited use.
  12. S-Man

    S-Man Kinkless Tetrode Admirer

    If you build a low powered amp with a big power supply it will tend to sound powerful (used within its power limits).
  13. March Audio

    March Audio Trade: March Audio

    This is correct but incorrect.

    A drum rim shot is not a square wave. However, yes you are correct that a square wave has infinite odd harmonics. To reproduce a square perfectly you need infinite bandwidth.

    Analogue and Digital audio is band limited, starting at the microphone. Band limiting will change the waveform if there is content above the bandwidth recorded, but that does not mean it is audible.

    If you can't hear a 30 kHz harmonic from a live instrument you won't hear the fact that it is missing from a recording. Your ear hears the "modified" waveform in both instances. You can't hear 30kHz - period.
    Last edited: May 24, 2019
  14. Jim Audiomisc

    Jim Audiomisc pfm Member

    A DAC thread just encountered the reality of mic performance. Most studio mics tend to have a peak somewhere *below*, followed by a swift fall away into the HF. This means they tend if anything to turn any abrupt transient edge into a circa 15 kHz 'ring'.

    Hence for most of the decades when now 'classic' recordings were made there will be little in them above about 20kHz. And what there is will have been severely altered by the mics, etc, used. Plus, of course, having distortion products added later in the chain!

    My impression is that - with a few exceptions - mic manufacturers tend to dodge this by not publishing reliable measurements of the response of their models. And also usually stopping any plot before it goes above about 20kHz. I've also seen catalogues where the same response is given for all the mics.
  15. Jim Audiomisc

    Jim Audiomisc pfm Member

    BTW as per above: A rimshot or other real-world impact in music is *not* a discontinuity. The elasticity of the materials and the finite velocities of sound in them mean it generates a finite rise time. Hence the point that the result won't give an infinite bandwidth. Observing this is hard because normal microphones can't respond fast enough anyway.
  16. ToTo Man

    ToTo Man the band not the dog

    If a frequency is beyond the limits of a person's hearing, can it still damage their hearing? e.g. if one's hearing tops out at say 12kHz, would sustained exposure to a high intensity 20kHz sine wave cause further deterioration even though it is inaudible to that person?
  17. JensenHealey

    JensenHealey pfm Member

    Quite possibly - physical damage could still occur, even if you do not 'hear' it. The 'hearing' but is the hairs being triggered and nerves going to the brain processing centre. But non-heard damage can still happen to the ear drum and the vibrating bones.

    Not quite the same but a chap I work with got a perforated ear drum at a Bruce Springsteen concert a few years ago. So loud noise can cause physical damage. It has, I believe, healed.
  18. ToTo Man

    ToTo Man the band not the dog

    If you were to hazard a guess, would you say your colleague's perforated ear drum was caused by low frequency content? I've always worn ear plugs to music events (initially the 30dB yellow foamy thIngs then latterly the Christmas tree shaped 15dB-20dB Alpine/Etymotic type that don't kill the mids and highs too much), but none of the plugs I've tried take any edge off the bass, presumably because most of it is conducted through the body. My worst experience ever was a band that cranked a sub-sonic synth to "11" during the intro of a song which literally made me feel like my brain was going to explode!

    It is of course possible to sustain perforated ear drums during typical daily activities, e.g. contact sports, altitude changes, infections, etc. I'm growing increasingly paranoid about trying to protect my hearing... it drives me mad when someone slams the car door or boot shut when I'm still in it (the car that is, not the boot! :D). The impact this has on my ear drums is very uncomfortable!
  19. JensenHealey

    JensenHealey pfm Member

    No idea!

    Yes - I went to a Muse concert with my daughter - my g it was loud! On the threshold of pain. My daughter was next to me, I could not hear her when she was shouting straight into my ear.

    But many concerts these days are much more reasonable.

    Off to Roger Hodgson at the Royal Albert Hall tomorrow night. Seats around the back of the stage was all I could get.
  20. Jim Audiomisc

    Jim Audiomisc pfm Member

    A musician recently won a court case against the ROH for hearing damage caused by being required to sit just in front of the horn/brass section. Given this I suspect some amplified concerts might be exposing themselves to similar cases in due time. If you can't hear someone speaking next to you, the 'music' (sic) is too loud.

    FWIW My better half and I have often walked out of out local theatre because the 're-inforcement' of the singing on stage is too <expletive> loud and hurts our ears. Really unpleasant.

    I've spoken at length with the people concerned, and they ain't... I can only conclude that people swiftly go partially deaf. But it is genuinely painfully loud and obviously distorted. Bonkers.
    Snufkin likes this.

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