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Amplifier power
In article , Eeyore
wrote: Jim Lesurf wrote: Eeyore wrote: If you look at what Stewart wrote (Hi, Stewart! :-) ) that seems to be comparing the effect of the room reverb with a situation where such reverb would be absent. At least that is my understanding of his saying, "...having them in an average living room gives you another 3dB or so of reverberant sound..." If that is wrong, I'm sure he will correct me, but that was what I then was referring to. Sorry if you didn't follow what I wrote. It's certainly true that a domestic room will have a far or ambient field that is greater than an anechoic chanber. Ever been in one btw ? Yes. Although 'retired' as an academic I still have my old University anechoic chamber as a 'lab'. (This translates to my also using its anteroom as my 'office' when in the physics building. :-) ) They're really odd. Indeed. :-) But then again does one listen to one's speakers at 1 metre distance usually ? so the SPL will have dropped off by X dB anyway by the time it reaches the sofa. Indeed. That will tend to happen. Are you familiar with nearfield and farfield measurements ? Yes - although you haven't said which particular mechanisms you have in mind for the factor(s) which affect how they differ, so I don't know which one(s) you have in mind. Have you read the article I referred to? Don't need to. In the near field, SPL will drop off at a rate of 6dB per doubling of distance (inverse square law). You haven't noticed that close-in that general assumption may break down? Consider what happens for example when your distance from the source is both less than a wavelength and less than a source diameter. Have you seen the AES papers, etc, that deal with sound levels close in? There is an analogy here with RF antennas. Near to the antenna the fields are not simply 'radiated in free space', and the change in level with nominal distance isn't inverse square. Nor is the wave impedance always the same as for open space propagation. So the difficulty here is that 'near field' has more than one defining meaning. For room acoustics it may mean relative to the boundary between being dominated by the direct radiation and the reverberant. But there are other effects. In the far field it's anyone's guess due to all the factors previously mentioned. Where the far field begins depends the size of your room and those other factors. Indeed. This is one of the reasons the MF 'sliderule' was somewhat misleading. BTW I just paused as I heard that Winter is approaching. The geese are flying over. So loud that I can hear them though the double-glazing. Nice sound, but sorry to wave farewell to summer... Slainte, Jim -- Change 'noise' to 'jcgl' if you wish to email me. Electronics http://www.st-and.ac.uk/~www_pa/Scot...o/electron.htm Armstrong Audio http://www.audiomisc.co.uk/Armstrong/armstrong.html Audio Misc http://www.audiomisc.co.uk/index.html |
Amplifier power
In article
, wrote: Jim Lesurf wrote: However if your audiolab seems to you not to clip or overheat I doubt you will have a problem with most other = 50Wpc amps in terms of power unless your speakers drop to low impedance. The 8000 series tends to have pokey small heatsinks[1], but can IIRC deliver reasonably high peak currents. Above said, I haven't yet seen you say anything that makes me feel you would benefit from a new amp. Except perhaps in the way of feeling pleased to own and use a newer and - allegedly - 'better' one. Well the phono sockets needed replacing 18 months ago - I'd like an amp with sockets which don't self destruct. I'm not sure that phono-socket lifetime is a spec you will find quoted for most amps. :-) Why did they need replacing? The 8000 I have was given to me by a colleague as one of the drivers had blown, but the sockets seem fine. Slainte, Jim -- Change 'noise' to 'jcgl' if you wish to email me. Electronics http://www.st-and.ac.uk/~www_pa/Scot...o/electron.htm Armstrong Audio http://www.audiomisc.co.uk/Armstrong/armstrong.html Audio Misc http://www.audiomisc.co.uk/index.html |
Amplifier power
In article , John Phillips
wrote: On 2008-10-14, Jim Lesurf wrote: In article , Eeyore wrote: Jim Lesurf wrote: I also still have my natty copy of the 'sliderule' he had sent out with one issue of HFN. This seems to imply I should change to a more powerful amp. I confess seeing this was one of the things that prompted my curiosity and lead to the HFN article I mentioned. Like yourself, I suspect, I've spent far more hours than any sane person should watching a scope display, etc, of power amp output whilst playing music to see what demands the music waveforms place on the amp and speakers. Some time ago John Crabbe reported published work in which listeners' perception of the same absolute loudness was rather different when they were listening in a large concert hall compared to a domestic listening room. This would suggest you do indeed need less in SPL terms at home than you get in the auditorium. Yes. I should make a public acknowledgement to JC here for that. I had read his articles and long since forgotten about them. He then saw my article and politely pointed out his own. I should have mentioned his articles as references for people to check out. Will do so if I get a chance to write more on the topic. He - and some readers - described the perception as being a sort of audio claustrophobia. This seems to be due to the short-time-delay nature of the reflections in small domestic rooms. So the work in my article may point at the cause. But at present it is hard to say for sure as there is a lack of experimental data so far as I am aware. Slainte, Jim -- Change 'noise' to 'jcgl' if you wish to email me. Electronics http://www.st-and.ac.uk/~www_pa/Scot...o/electron.htm Armstrong Audio http://www.audiomisc.co.uk/Armstrong/armstrong.html Audio Misc http://www.audiomisc.co.uk/index.html |
Amplifier power
In article , Eeyore
wrote: John Phillips wrote: Jim Lesurf wrote: Eeyore wrote: Jim Lesurf wrote: I also still have my natty copy of the 'sliderule' he had sent out with one issue of HFN. This seems to imply I should change to a more powerful amp. I confess seeing this was one of the things that prompted my curiosity and lead to the HFN article I mentioned. Like yourself, I suspect, I've spent far more hours than any sane person should watching a scope display, etc, of power amp output whilst playing music to see what demands the music waveforms place on the amp and speakers. Some time ago John Crabbe reported published work in which listeners' perception of the same absolute loudness was rather different when they were listening in a large concert hall compared to a domestic listening room. This would suggest you do indeed need less in SPL terms at home than you get in the auditorium. Because the nearfield and farfield are closer at home. You may be confusing cause and effect with a situation where the same mechanism is causing two effects. :-) Slainte, Jim -- Change 'noise' to 'jcgl' if you wish to email me. Electronics http://www.st-and.ac.uk/~www_pa/Scot...o/electron.htm Armstrong Audio http://www.audiomisc.co.uk/Armstrong/armstrong.html Audio Misc http://www.audiomisc.co.uk/index.html |
Amplifier power
In article , Eeyore
wrote: Marky P wrote: tony sayer wrote: I Wonder how may pro recording bits of gear are around with 5532's;).. Just about most of it in current use. Are they at all similar to 5534's? Sure I used them in a phono pre-amp in the 80's, copied out of a R. A. Penfold book. Yes, they're the dual version and about 3dB noisier although not quite sure why. Not knowing why, my immediate suspicion was substrate noise caused by having two lots of bias currents. But that is just a spur of the moment guess. :-) FWIW I came to prefer the HA12017 as a general purpose audio op-amp. But I appreciate this is quite a weird choice. Slainte, Jim -- Change 'noise' to 'jcgl' if you wish to email me. Electronics http://www.st-and.ac.uk/~www_pa/Scot...o/electron.htm Armstrong Audio http://www.audiomisc.co.uk/Armstrong/armstrong.html Audio Misc http://www.audiomisc.co.uk/index.html |
Amplifier power
In article , Eeyore rabbitsfriendsandrel
scribeth thus Robert Orban wrote: says... Seems to be tricky to find anything actually. This mic has a max input SPL of 134dB which receives the comment "Hi-SPL handling is perfect for suspension over choirs and orchestras" http://www.dv247.com/invt/11582/ Try this: Dynamic-Range Requirement for Subjectively Noise-Free Reproduction of Music JAES Volume 30 Issue 7/8 pp. 504-511; August 1982 A dynamic range of up to 118 dB is determined necessary for subjectively noise-free reproeuction of music in an audio recorder with a white-noise floor. Maximum peak sound-pressure levels in music are compared to the minimum discernible level of white noise in a quiet listening situation. Microphone noise limitations, monitoring loudspeaker capabilities, and performance environment noise levels are also considered. Author: Fielder, Louis D. Affiliation: Ampex Corporation, Redwood City, CA Well, I never imagined I'd have Bob Orban backing me up on a technical issue ! Thanks Bob ! Graham Him being the one who will be criticised on other groups for making DAB and FM ever more distorted;!... -- Tony Sayer |
Amplifier power
In article , Anton Gÿsen
scribeth thus tony sayer wrote: In article s.com, scribeth thus Jim Lesurf wrote: However if your audiolab seems to you not to clip or overheat I doubt you will have a problem with most other = 50Wpc amps in terms of power unless your speakers drop to low impedance. The 8000 series tends to have pokey small heatsinks[1], but can IIRC deliver reasonably high peak currents. Above said, I haven't yet seen you say anything that makes me feel you would benefit from a new amp. Except perhaps in the way of feeling pleased to own and use a newer and - allegedly - 'better' one. Well the phono sockets needed replacing 18 months ago - I'd like an amp with sockets which don't self destruct. Phileas Wonder if that was a poor batch none of mine are duff at all!... I believe it's a common problem with 8000As. Well I've got Four of them and their all fine;!... Funnily enough we've got four Band 1 transmitters , yes those frequencies are still used, and the cores in one have all disintegrated away whereas in the other their fine all about the same age!.. What is it that fails, the plastic moulding?.. -- Tony Sayer |
Amplifier power
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Amplifier power
In article ,
Robert Orban wrote: In article , says... ..and there's also this, which explicitly references peak level measurements: Pre- and Postemphasis Techniques as Applied to Audio Recording Systems JAES Volume 33 Issue 9 pp. 649-658; September 1985 Thanks for the above. I've now had a chance to have a quick read-though of it. I've probably missed things, and would need to check some of its references, but my initial reactions were... Firstly, that the levels reported are somewhat larger than asserted by others elsewhere - e.g. already in this thread is values from MF. This tends to support my suspicion that people assert numbers which may be misleading if they don't actually know where they came from at origin. Hence my preference for measured results. :-) I wonder how that may relate to the following. Secondly, that the paper doesn't give any real details of the peak meter used. For example, not the bandwidth when 'flat', nor the response times of the peak function. e.g. no value for underread of something like a bandwidth-limited impulse. This might well affect results, but hard to say more without any details. Thirdly that the stats seem to be on a 'peak per concert' basis IIUC. Makes me wonder what the time stats are as that might be a better guide. However, thanks, very interesting. :-) Slainte, Jim -- Change 'noise' to 'jcgl' if you wish to email me. Electronics http://www.st-and.ac.uk/~www_pa/Scot...o/electron.htm Armstrong Audio http://www.audiomisc.co.uk/Armstrong/armstrong.html Audio Misc http://www.audiomisc.co.uk/index.html |
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