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Amplifier power
In article
, wrote: Jim Lesurf wrote: It would depend on various factors: What kind of music you like. How large your listening room is. What speakers you will be using. etc. Classical music - not excessively loudly but of course orchestral climaxes can be loud. Digital sources - not vinyl. Room 11' x 13' x 8' high (rather small probably for the speakers Focal JMLab Chorus 714V Power handling 130W max (90W nom) Sensitivity 91dB) ... or just to start an argument. :-) I've been thinking I'd like to "upgrade" my 20yr old Audiolab 8000A (50W) in the near future. I was thinking of spending up to £1000 but if I don't need to spend that much I won't. I have the feeling that there is no specific *audible* reasons for your feeling that you should "upgrade". If this is so, my reaction is to continue to use what you have and spend the money on something else. e.g. loads more CDs, or LPs, or whatever music you favour. Enjoy the music, not the equipment-ownership. :-) 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: On Oct 13, 9:10 am, Jim Lesurf wrote: And even if they do, the trouble with listening in shops is that the listening room is very different from where I will be using the amplifier. Indeed. However that is a vastly harder problem when choosing speakers than amplifiers. And you seem to have chosen your speakers, so this can't be impossibly difficult. :-) Well, the room in which I compared the speakers was quite a bit bigger than my actual listening room (11'x13'x8') so I'm not sure really whether I chose the best of the three I compared. They are probably too big for my room but then I don't need to have them very loud to "fill" it. This is the difficulty with comparing in shops. Yes. And it tends to matter far less when choosing an amplifier than speakers. If in doubt, make sure they have a larger room than yours, and try to get them to play the amp with speakers that have a lower efficiency and lower impedance. This will make it likely the amp has enough power for you if OK in the shop. 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. Slainte, Jim [1] The 8000A I have in bits has heatsinks smaller than my old Armstrong 626s. Both designs have tiny heatsinks by 'super fi' standards. (Although the 8000 disguises this by hiding them inside the box.) Yet generally they work fine for classical or other acoustic and uncompressed music without overheating. -- 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: wrote: Jim Lesurf wrote: It would depend on various factors: What kind of music you like. How large your listening room is. What speakers you will be using. etc. Classical music - not excessively loudly but of course orchestral climaxes can be loud. Digital sources - not vinyl. Room 11' x 13' x 8' high (rather small probably for the speakers Focal JMLab Chorus 714V Power handling 130W max (90W nom) Sensitivity 91dB) An orchestra even in the auditorium can peak at over 120dB. To recreate that with 90 odd dB sensitivity speakers requires a 1kW / ch amp. Probably true if you listen outdoors. :-) That's why decent studios have such things. Probably about 6 of them for 5.1 sound. Do studios routinely use speakers with a 90dB sensitivity? Afraid I don't know much about that area, but assumed they used speakers of types that would be less sensitive. Also that their room acoustics and normal levels different to most domestic replay. 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
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Amplifier power
Jim Lesurf wrote: wrote: On 14 Oct, 00:40, Eeyore wrote: John Phillips wrote: Eeyore wrote: wrote: An orchestra even in the auditorium can peak at over 120dB. Do you have a reference for this? I have been looking for credible sources for peak orchestral SPLs in the auditorium for a long while. It's a 'well known fact' amongst audio professionals. Google it. For some reason I have come to be wary of claims thrown around on the basis of being a "well known fact". It was actually intentionally slightly tongue in cheek, but remeber I am referring to PEAK levels not average levels which dB meters read. That sometimes seems to mean, "Loads of people have been saying it to one another on the basis that someone else told them. They've been doing this for so long that no-one can recall who made it up in the first place." :-) See above. In other words completely useless because they haven't the tiniest clue what they're measuring. Thankfully or even orchestras would have to be banned from playing for HSE reasons. However I have only semi-credible figures for places in the auditorium and they only go up to 109 dB SPL. IIRC I read an old article by John Crabbe a while ago that reported measurements. I can't recall details, but if I do I'll report them. Clearly then, you'll know that having two speakers increases the nominal sensitivity by 3dB for a central sound, and having them in an average living room gives you another 3dB or so of reverberant sound, so you can hit a 120dB peak from 91 db/watt speakers with about 23dB of amp power, which is 200 watts. Not trivial, but readily obtainable from many modern amps. FWIW The effect of room reverb in UK domestic rooms might be somewhat higher than a 3dB gain. I did some analysis of this a while ago (see Hi Fi News August 2008). Hard to give a figure as it will probably vary from room to room, but 3dB may be on the low side as an estimate of what is typical. IIRC some texts also give details that indicate well above 3dB for this. 3dB relative to WHAT ? Are you familiar with nearfield and farfield measurements ? That said (again as discussed in the HFN article) there is a distinction between the actual instantaneous peak measured power, and the peak level perceived, due to the way human hearing tends to 'integrate' the effect of short term delayed reflections into one percieved peak. Quite. It's not simple. Graham |
Amplifier power
tony sayer wrote: Eeyore scribeth thus tony sayer wrote: I reckon you'd be well pushed to improve of the Audiolab excellent amplifier even at 20 years old:)).. You must be living in a very weird world then. Its design is utterly 'agricultural' by today's standards. It's barely any better than a decent semiconductor manufacturer's application note of that era. Frankly it's a joke. Plus any one you can find will need total re-capping of the electrolytics. Graham (pro-audio designer with 37 yrs experience) Bet you'd be hard pressed to tell one apart in a listening test!.. No perhaps not.. their prolly too neutral for your linking;!... If you want neutral you need one of my ultra-performance mosfet designs. The actual 'amp block' has a THD+N of 0.0008% @ 1 kHz (SINAD -103dB) measured on an AP with a residual THD+N of 0.0007% ! The 'back calculates' to a true THD of 0.0004% (SINAD -108dB). The response is VERY flat too. About -0.2dB @ 10 Hz and 20kHz IIRC. Oh and I designed it about 19 years ago. Sadly, the figure is degraded by the op-amp front end (5532s) ! But I could replace these with LME49720s instead. Graham |
Amplifier power
Jim Lesurf wrote: wrote: On 14 Oct, 00:40, Eeyore wrote: John Phillips wrote: Eeyore wrote: wrote: An orchestra even in the auditorium can peak at over 120dB. Do you have a reference for this? I have been looking for credible sources for peak orchestral SPLs in the auditorium for a long while. It's a 'well known fact' amongst audio professionals. Google it. For some reason I have come to be wary of claims thrown around on the basis of being a "well known fact". http://www.musicalfidelity.com/produ..._response.html " We know for a fact that concert hall peak sound pressure level (SPL) for a medium sized symphony orchestra is 109-110dB. For a big symphony orchestra or rock concert the levels are much higher." And the nearer you sit ! Graham |
Amplifier power
Jim Lesurf wrote: Eeyore wrote: wrote: Jim Lesurf wrote: It would depend on various factors: What kind of music you like. How large your listening room is. What speakers you will be using. etc. Classical music - not excessively loudly but of course orchestral climaxes can be loud. Digital sources - not vinyl. Room 11' x 13' x 8' high (rather small probably for the speakers Focal JMLab Chorus 714V Power handling 130W max (90W nom) Sensitivity 91dB) An orchestra even in the auditorium can peak at over 120dB. To recreate that with 90 odd dB sensitivity speakers requires a 1kW / ch amp. Probably true if you listen outdoors. :-) That's why decent studios have such things. Probably about 6 of them for 5.1 sound. Do studios routinely use speakers with a 90dB sensitivity? Afraid I don't know much about that area, but assumed they used speakers of types that would be less sensitive. Also that their room acoustics and normal levels different to most domestic replay. Check out the big ATCs. Virtually THE standard. http://www.atc.gb.net/downloads/PRO_P18-19.pdf It's active but see the amp specs and the max SPL of 121dB. I know studios with 6 of these in a control room. Graham |
Amplifier power
In article , Eeyore
wrote: Jim Lesurf wrote: wrote: On 14 Oct, 00:40, Eeyore wrote: It's a 'well known fact' amongst audio professionals. Google it. For some reason I have come to be wary of claims thrown around on the basis of being a "well known fact". It was actually intentionally slightly tongue in cheek, but remeber I am referring to PEAK levels not average levels which dB meters read. I was aware of that. For all I know, the claim is quite accurate. But the problem is the one I described. That sometimes seems to mean, "Loads of people have been saying it to one another on the basis that someone else told them. They've been doing this for so long that no-one can recall who made it up in the first place." :-) See above. See above. :-) Clearly then, you'll know that having two speakers increases the nominal sensitivity by 3dB for a central sound, and having them in an average living room gives you another 3dB or so of reverberant sound, so you can hit a 120dB peak from 91 db/watt speakers with about 23dB of amp power, which is 200 watts. Not trivial, but readily obtainable from many modern amps. FWIW The effect of room reverb in UK domestic rooms might be somewhat higher than a 3dB gain. I did some analysis of this a while ago (see Hi Fi News August 2008). Hard to give a figure as it will probably vary from room to room, but 3dB may be on the low side as an estimate of what is typical. IIRC some texts also give details that indicate well above 3dB for this. 3dB relative to WHAT ? 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. 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? That said (again as discussed in the HFN article) there is a distinction between the actual instantaneous peak measured power, and the peak level perceived, due to the way human hearing tends to 'integrate' the effect of short term delayed reflections into one percieved peak. Quite. It's not simple. That was indeed, part of my point. :-) 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: Jim Lesurf wrote: For some reason I have come to be wary of claims thrown around on the basis of being a "well known fact". http://www.musicalfidelity.com/produ..._response.html " We know for a fact that concert hall peak sound pressure level (SPL) for a medium sized symphony orchestra is 109-110dB. For a big symphony orchestra or rock concert the levels are much higher." Interesting that he seems able to narrow down all orchestras to a 1dB range like that. Reminiscent of the way undergrads sometimes write down a lab experiment result to as many significant figures as their hand calculator displays - regardless of having input figures only roughly accurate. :-) 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. My personal conclusion was that his sliderule rather over-egged how much amplifier power I'd need for my domestic use. However my listening room is somewhat smaller than the Royal Festival Hall... ;- As I wrote, it seems common for people to make assertions on the basis of "we know that", or "everyone knows that". But alas making such a claim does not automatically make an assertion true. Of course, that doesn't make it false, either. And the nearer you sit ! ....although of course since you mentioned nearfield versus farfield in another posting you will doubtless be aware that this does not always follow the 1/r^2 law you might expect from school physics books. :-) Like John Phillips I've seen assertions about this on many occasions. However also like him, I can't recall seeing reliable peak measurement values. Although I do recall reading recently the old article by JC I can't currently remember which back-issue this was, or what values her got. The peaks may well reach 120dB [1], that seems quite possible to me. But plausible assumptions or assertions aren't actually measured results. As I explained, I've seen all kinds of claims made by people on the "everyone knows" basis, and have become wary of simply believing everything I'm told. Up to you what you believe, but I'd prefer evidence when possible. Slainte, Jim [1] You might apply your own "reference what?" question here, BTW. :-) -- 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
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Amplifier power
In article , Eeyore
wrote: Jim Lesurf wrote: Eeyore wrote: To recreate that with 90 odd dB sensitivity speakers requires a 1kW / ch amp. Probably true if you listen outdoors. :-) That's why decent studios have such things. Probably about 6 of them for 5.1 sound. Do studios routinely use speakers with a 90dB sensitivity? Afraid I don't know much about that area, but assumed they used speakers of types that would be less sensitive. Also that their room acoustics and normal levels different to most domestic replay. Check out the big ATCs. Virtually THE standard. http://www.atc.gb.net/downloads/PRO_P18-19.pdf It's active but see the amp specs and the max SPL of 121dB. I know studios with 6 of these in a control room. For the above to answer the actual question I asked, you would have to be saying that the above comprises a "90 odd dB" sensitivity speaker with a 1 kW amp. Is that what you were saying? From the specs, I suspect not. The ATC seems to have four amps, each connected to an individual drive unit. The amp powers do total a nominal 850W, but this arrangement doesn't seem to be what you were referring to above. The way you used "90 odd dB sensitivity", etc, seem to presume a speaker driven by a single amp and with an nominal '1W 8 Ohms' as the sensitivity ref. Or did you mean something other than the common way of quoting sensitivities used for passive domestic speakers? You seem to be mixing apples with oranges here. Also, the above seems to be 121dB SPL. I thought at an earlier point we discussing peaks - i.e. not time-averaged levels. Were you saying that orchestras deliver 'peaks' with a short-term level of 120dB, or that the instantaneous peak is 120dB? The MF document you quoted was claiming levels of 109-110dB SPL and I assumed that was time-averaged from the use of 'SPL'. So there does seem to be some ambiguity in the figures being claimed or asserted. I appreciate, though, that the ATC should be able to wake you up if placed just 1m from your ear. Would make an impressive bedside alarm radio. :-) 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
Jim Lesurf wrote: Eeyore wrote: Jim Lesurf wrote: FWIW The effect of room reverb in UK domestic rooms might be somewhat higher than a 3dB gain. I did some analysis of this a while ago (see Hi Fi News August 2008). Hard to give a figure as it will probably vary from room to room, but 3dB may be on the low side as an estimate of what is typical. IIRC some texts also give details that indicate well above 3dB for this. 3dB relative to WHAT ? 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 ? They're really odd. 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. 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). 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. That said (again as discussed in the HFN article) there is a distinction between the actual instantaneous peak measured power, and the peak level perceived, due to the way human hearing tends to 'integrate' the effect of short term delayed reflections into one percieved peak. Quite. It's not simple. That was indeed, part of my point. :-) Ok. Graham |
Amplifier power
Jim Lesurf wrote: Eeyore wrote: Jim Lesurf wrote: For some reason I have come to be wary of claims thrown around on the basis of being a "well known fact". http://www.musicalfidelity.com/produ..._response.html " We know for a fact that concert hall peak sound pressure level (SPL) for a medium sized symphony orchestra is 109-110dB. For a big symphony orchestra or rock concert the levels are much higher." Interesting that he seems able to narrow down all orchestras to a 1dB range like that. Reminiscent of the way undergrads sometimes write down a lab experiment result to as many significant figures as their hand calculator displays - regardless of having input figures only roughly accurate. :-) 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. My personal conclusion was that his sliderule rather over-egged how much amplifier power I'd need for my domestic use. However my listening room is somewhat smaller than the Royal Festival Hall... ;- As I wrote, it seems common for people to make assertions on the basis of "we know that", or "everyone knows that". But alas making such a claim does not automatically make an assertion true. Of course, that doesn't make it false, either. And the nearer you sit ! ...although of course since you mentioned nearfield versus farfield in another posting you will doubtless be aware that this does not always follow the 1/r^2 law you might expect from school physics books. :-) Like John Phillips I've seen assertions about this on many occasions. However also like him, I can't recall seeing reliable peak measurement values. Although I do recall reading recently the old article by JC I can't currently remember which back-issue this was, or what values her got. The peaks may well reach 120dB [1], that seems quite possible to me. But plausible assumptions or assertions aren't actually measured results. As I explained, I've seen all kinds of claims made by people on the "everyone knows" basis, and have become wary of simply believing everything I'm told. Up to you what you believe, but I'd prefer evidence when possible. Slainte, Jim [1] You might apply your own "reference what?" question here, BTW. :-) 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/ Graham |
Amplifier power
tony sayer wrote: Eeyore scribeth thus tony sayer wrote: Eeyore scribeth thus tony sayer wrote: I reckon you'd be well pushed to improve of the Audiolab excellent amplifier even at 20 years old:)).. You must be living in a very weird world then. Its design is utterly 'agricultural' by today's standards. It's barely any better than a decent semiconductor manufacturer's application note of that era. Frankly it's a joke. Plus any one you can find will need total re-capping of the electrolytics. Graham (pro-audio designer with 37 yrs experience) Bet you'd be hard pressed to tell one apart in a listening test!.. No perhaps not.. their prolly too neutral for your linking;!... If you want neutral you need one of my ultra-performance mosfet designs. The actual'amp block' has a THD+N of 0.0008% @ 1 kHz (SINAD -103dB) measured on an AP with a residual THD+N of 0.0007% ! That 'back calculates' to a true THD of 0.0004% (SINAD -108dB). The response is VERY flat too. About -0.2dB @ 10 Hz and 20kHz IIRC. Oh and I designed it about 19 years ago. Sadly, the figure is degraded by the op-amp front end (5532s) ! But I could replace these with LME49720s instead. Humm... I Wonder how may pro recording bits of gear are around with 5532's;).. Just about most of it in current use. Did you check the spec of the LME49720 ? http://www.national.com/pf/LM/LME49720.html They had to devise a special method to measure the THD without the noise dominating. They're not even that shockingly expensive. Graham |
Amplifier power
Eeyore writes:
Rob wrote: I have a 20 year old (at least) NAD 3020 - works perfectly but sounds distinctly soft/mellow compared to a newish SS amp, and indeed an even older Pioneer receiver. Is this a symptom of old caps, and/or poor design? I know the 3020 moderately well. It was very well regarded (and designed - I fact I met the designer) and should still sound at least decent today. At that age, recapping the electrolytic caps specifically is likely to be a good move. Especially if you're competent with a soldering iron yourself or have a friend who is. The parts won't cost much. So true. Some ten years ago I did this to a ten plus but not quite twenty years old amp (not NAD) and the improvement was a jaw dropper. -- Martin Schöön "Problems worthy of attack show their worth by hitting back." Piet Hein |
Amplifier power
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 |
Amplifier power
On 2008-10-13, Eeyore wrote:
John Phillips wrote: Eeyore wrote: wrote: Jim Lesurf wrote: It would depend on various factors: What kind of music you like. How large your listening room is. What speakers you will be using. etc. Classical music - not excessively loudly but of course orchestral climaxes can be loud. Digital sources - not vinyl. Room 11' x 13' x 8' high (rather small probably for the speakers Focal JMLab Chorus 714V Power handling 130W max (90W nom) Sensitivity 91dB) An orchestra even in the auditorium can peak at over 120dB. Do you have a reference for this? I have been looking for credible sources for peak orchestral SPLs in the auditorium for a long while. It's a 'well known fact' amongst audio professionals. Google it. I have indeed Googled it rather extensively. What I mostly see is unsupported assertion that seems to have been copied without question from unsupported sources. I have seen no good, well-documented evidence. This is why I am interested in asking. I have quite a few health & safety measurements of very good credibility inside the orchestra and a few at the conductor's rostrum. In other words completely useless because they haven't the tiniest clue what they're measuring. Thankfully or even orchestras would have to be banned from playing for HSE reasons. You have it quite wrong. The H&S reports (typically for North American orchestras) are not always perfect but they usually are good enough at specifying the instrument and what it was set to measure. On the credibility scale they rate generally well. I am happy to accept peak levels inside the orchestra well on the eye-watering side of 130 dB SPL. However while these are good enough measurements for checking musicians' exposure to sound, they don't give the positional data for source and measurement to allow projection to levels in the auditorium. However I have only semi-credible figures for places in the auditorium and they only go up to 109 dB SPL. A or C weighted on fast or slow response ? The average dB meter is about as useful as a wet blanket when measuring either impulses or frankly most music. There is no correlation between industrial hearing damage levels as measured by a typical dB meter and music because the waveforms and wavefronts are WILDLY different. Good questions - these are exactly why I am not happy with the "semi-credible" source in question. BTW this particular source was the one Musical Fidelity used in the advertising that's been brought up later in this thread. And used by HFN in its fairly recent "how much power do you need" articles. So, at the risk of giving offence I am afraid I am still not prepared to assign any credibility to unsupported assertions of "well known fact". For exactly the reasons you state. That's why I am still interested in seeking credible, well supported data. -- John Phillips |
Amplifier power
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. -- John Phillips |
Amplifier power
Martin Schöön wrote:
Eeyore writes: Rob wrote: I have a 20 year old (at least) NAD 3020 - works perfectly but sounds distinctly soft/mellow compared to a newish SS amp, and indeed an even older Pioneer receiver. Is this a symptom of old caps, and/or poor design? I know the 3020 moderately well. It was very well regarded (and designed - I fact I met the designer) and should still sound at least decent today. At that age, recapping the electrolytic caps specifically is likely to be a good move. Especially if you're competent with a soldering iron yourself or have a friend who is. The parts won't cost much. So true. Some ten years ago I did this to a ten plus but not quite twenty years old amp (not NAD) and the improvement was a jaw dropper. Mmm, might have a look into that then, thanks. It's more a nostalgia thing - some desperate attempt to relive my youth :-) Rob |
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"John Phillips" wrote in message
... On 2008-10-13, Eeyore wrote: wrote: Jim Lesurf wrote: It would depend on various factors: What kind of music you like. How large your listening room is. What speakers you will be using. etc. Classical music - not excessively loudly but of course orchestral climaxes can be loud. Digital sources - not vinyl. Room 11' x 13' x 8' high (rather small probably for the speakers Focal JMLab Chorus 714V Power handling 130W max (90W nom) Sensitivity 91dB) An orchestra even in the auditorium can peak at over 120dB. Do you have a reference for this? I have been looking for credible sources for peak orchestral SPLs in the auditorium for a long while. I have quite a few health & safety measurements of very good credibility inside the orchestra and a few at the conductor's rostrum. However I have only semi-credible figures for places in the auditorium and they only go up to 109 dB SPL. -- John Phillips Funny that - and I'm not psychic. Before I finished reading the first paragraph of your reply the number 109 was in my mind. Then I read the second paragraph.... we must have read the same comic at some time (I have one of those memories for numbers.) -- Woody harrogate three at ntlworld dot com |
Amplifier power
In article , Eeyore rabbitsfriendsandrela
scribeth thus Jim Lesurf wrote: Eeyore wrote: Jim Lesurf wrote: For some reason I have come to be wary of claims thrown around on the basis of being a "well known fact". http://www.musicalfidelity.com/produ..._response.html " We know for a fact that concert hall peak sound pressure level (SPL) for a medium sized symphony orchestra is 109-110dB. For a big symphony orchestra or rock concert the levels are much higher." Interesting that he seems able to narrow down all orchestras to a 1dB range like that. Reminiscent of the way undergrads sometimes write down a lab experiment result to as many significant figures as their hand calculator displays - regardless of having input figures only roughly accurate. :-) 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. My personal conclusion was that his sliderule rather over-egged how much amplifier power I'd need for my domestic use. However my listening room is somewhat smaller than the Royal Festival Hall... ;- As I wrote, it seems common for people to make assertions on the basis of "we know that", or "everyone knows that". But alas making such a claim does not automatically make an assertion true. Of course, that doesn't make it false, either. And the nearer you sit ! ...although of course since you mentioned nearfield versus farfield in another posting you will doubtless be aware that this does not always follow the 1/r^2 law you might expect from school physics books. :-) Like John Phillips I've seen assertions about this on many occasions. However also like him, I can't recall seeing reliable peak measurement values. Although I do recall reading recently the old article by JC I can't currently remember which back-issue this was, or what values her got. The peaks may well reach 120dB [1], that seems quite possible to me. But plausible assumptions or assertions aren't actually measured results. As I explained, I've seen all kinds of claims made by people on the "everyone knows" basis, and have become wary of simply believing everything I'm told. Up to you what you believe, but I'd prefer evidence when possible. Slainte, Jim [1] You might apply your own "reference what?" question here, BTW. :-) 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/ Graham Can't say any prom or other concert I've been to this year was "that" loud and most we're quite quiet;).. -- Tony Sayer |
Amplifier power
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Amplifier power
In article , Eeyore wrote:
Rob wrote: Eeyore wrote: Once only wrote: wrote in message If all (properly designed) amps sound the same, how do I decide which amp to buy? Is it just a case of choosing one with sufficient power output and how do I determine this? No, thats not true - the myth of long wire with gain. Amplifiers can have very similar specs but have different sonic characters and abilities. Bandwidth and an amps ability to pump out the amperes when fronted with an awkward load etc etc etc. If I were you the first thing is to not pay too much attention to the big girls blouses of this group. Do yourself a favour, don't heed mag reviewers advice either. Try the pre-owned market, plenty of stereo bargains to be had. This is just one example, the Pioneer A400 was a huge success because of it ultra wide stable bandwidth (5 - 100) and it's impressive ability to drive any loudspeaker and remain stable - thats the ability to churn out amperes! It sold by the truck load and often crops up in the for sale ads, and it is proven to be a rugged longstander, can be picked up for less than £100. But then there are others, Nad, and even Sony from the late 80's and early 90's. First port of call believe it or not would be Cash Converters, then the specialist pre-owned dealers, then the small ads. Once you've found a model, look it up! Don't bother with Naim or Arcam, over-priced and nothing special. But don't buy antiques. No matter how well they were supposed to sound. All the electrolytic caps will need replacing and standards weren't as high then. Modern amplifiers are much better on the whole. cross-posted intentionally to rec.audio tech I have a 20 year old (at least) NAD 3020 - works perfectly but sounds distinctly soft/mellow compared to a newish SS amp, and indeed an even older Pioneer receiver. Is this a symptom of old caps, and/or poor design? I know the 3020 moderately well. It was very well regarded (and designed - I fact I met the designer) and should still sound at least decent today. At that age, recapping the electrolytic caps specifically is likely to be a good move. Especially if you're competent with a soldering iron yourself or have a friend who is. The parts won't cost much. I have gone over many amps, and its really rare that I would need to replace the main caps. Many times the smaller caps will go bad. If I were really going over an amp in every detail, if I had plenty of time, then I might check the main caps, or even buffer them. Its likely an amp will sound just fine if not driven hard with lossy main caps. If it can obtain max power with resonable distortion then I would not touch the main caps. greg You don't have the 'soft clip' engaged do you ? That would make it mellower. Also clean ALL the input and output sockets. Damn RCA / phono / Cinch crap ! Funnily enough, around the time of the 3020 I nearly worked as a designer for NAD. The deal breaker was that I wanted to do it on contract and they wanted me full time. I can still remember the excellent lunch they took me out for btw ! Super Italian. Graham |
Amplifier power
On Tue, 14 Oct 2008 21:06:34 +0100, tony sayer
wrote: In article , Eeyore rabbitsfriendsandrel scribeth thus tony sayer wrote: Eeyore scribeth thus tony sayer wrote: Eeyore scribeth thus tony sayer wrote: I reckon you'd be well pushed to improve of the Audiolab excellent amplifier even at 20 years old:)).. You must be living in a very weird world then. Its design is utterly 'agricultural' by today's standards. It's barely any better than a decent semiconductor manufacturer's application note of that era. Frankly it's a joke. Plus any one you can find will need total re-capping of the electrolytics. Graham (pro-audio designer with 37 yrs experience) Bet you'd be hard pressed to tell one apart in a listening test!.. No perhaps not.. their prolly too neutral for your linking;!... If you want neutral you need one of my ultra-performance mosfet designs. The actual'amp block' has a THD+N of 0.0008% @ 1 kHz (SINAD -103dB) measured on an AP with a residual THD+N of 0.0007% ! That 'back calculates' to a true THD of 0.0004% (SINAD -108dB). The response is VERY flat too. About -0.2dB @ 10 Hz and 20kHz IIRC. Oh and I designed it about 19 years ago. Sadly, the figure is degraded by the op-amp front end (5532s) ! But I could replace these with LME49720s instead. Humm... 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. Marky P. |
Amplifier power
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Amplifier power
In article , Marky P
scribeth thus On Tue, 14 Oct 2008 21:06:34 +0100, tony sayer wrote: In article , Eeyore rabbitsfriendsandrel scribeth thus tony sayer wrote: Eeyore scribeth thus tony sayer wrote: Eeyore scribeth thus tony sayer wrote: I reckon you'd be well pushed to improve of the Audiolab excellent amplifier even at 20 years old:)).. You must be living in a very weird world then. Its design is utterly 'agricultural' by today's standards. It's barely any better than a decent semiconductor manufacturer's application note of that era. Frankly it's a joke. Plus any one you can find will need total re-capping of the electrolytics. Graham (pro-audio designer with 37 yrs experience) Bet you'd be hard pressed to tell one apart in a listening test!.. No perhaps not.. their prolly too neutral for your linking;!... If you want neutral you need one of my ultra-performance mosfet designs. The actual'amp block' has a THD+N of 0.0008% @ 1 kHz (SINAD -103dB) measured on an AP with a residual THD+N of 0.0007% ! That 'back calculates' to a true THD of 0.0004% (SINAD -108dB). The response is VERY flat too. About -0.2dB @ 10 Hz and 20kHz IIRC. Oh and I designed it about 19 years ago. Sadly, the figure is degraded by the op-amp front end (5532s) ! But I could replace these with LME49720s instead. Humm... 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. Marky P. Ones a single and ones a dual i.e. two Op amps in the one package and apart form some silly buggers usage their excellent chips for most all applications:)... -- Tony Sayer |
Amplifier power
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. |
Amplifier power
John Phillips wrote: Eeyore wrote: John Phillips wrote: Eeyore wrote: wrote: Jim Lesurf wrote: It would depend on various factors: What kind of music you like. How large your listening room is. What speakers you will be using. etc. Classical music - not excessively loudly but of course orchestral climaxes can be loud. Digital sources - not vinyl. Room 11' x 13' x 8' high (rather small probably for the speakers Focal JMLab Chorus 714V Power handling 130W max (90W nom) Sensitivity 91dB) An orchestra even in the auditorium can peak at over 120dB. Do you have a reference for this? I have been looking for credible sources for peak orchestral SPLs in the auditorium for a long while. It's a 'well known fact' amongst audio professionals. Google it. I have indeed Googled it rather extensively. What I mostly see is unsupported assertion that seems to have been copied without question from unsupported sources. I have seen no good, well-documented evidence. This is why I am interested in asking. I have quite a few health & safety measurements of very good credibility inside the orchestra and a few at the conductor's rostrum. In other words completely useless because they haven't the tiniest clue what they're measuring. Thankfully or even orchestras would have to be banned from playing for HSE reasons. You have it quite wrong. The H&S reports (typically for North American orchestras) are not always perfect but they usually are good enough at specifying the instrument and what it was set to measure. If they're anything like our HSE, they only ever measure dBA, which is absurdly wrong at high volume levels. I assume you know why ? On the credibility scale they rate generally well. I am happy to accept peak levels inside the orchestra well on the eye-watering side of 130 dB SPL. Very likely. However while these are good enough measurements for checking musicians' exposure to sound, they don't give the positional data for source and measurement to allow projection to levels in the auditorium. It's complex for 101 reasons. However I have only semi-credible figures for places in the auditorium and they only go up to 109 dB SPL. Undoubtedly averaged not peak. A or C weighted on fast or slow response ? The average dB meter is about as useful as a wet blanket when measuring either impulses or frankly most music. There is no correlation between industrial hearing damage levels as measured by a typical dB meter and music because the waveforms and wavefronts are WILDLY different. Good questions - these are exactly why I am not happy with the "semi-credible" source in question. BTW this particular source was the one Musical Fidelity used in the advertising that's been brought up later in this thread. And used by HFN in its fairly recent "how much power do you need" articles. So, at the risk of giving offence I am afraid I am still not prepared to assign any credibility to unsupported assertions of "well known fact". For exactly the reasons you state. That's why I am still interested in seeking credible, well supported data. I only wish I could quote you a Studio Sound article of about 30 years ago. As I said audio-pros understand it. Graham |
Amplifier power
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. Graham |
Amplifier power
tony sayer wrote: Eeyore scribeth thus Did you check the spec of the LME49720 ? http://www.national.com/pf/LM/LME49720.html They had to devise a special method to measure the THD without the noise dominating. They're not even that shockingly expensive. Shockingly enough in small quantities;!... From the likes of Farnell maybe £4 seems a lot but compare that to a $400 wooden volume control knob ! http://uk.farnell.com/1367613/semico...questid=131459 That's only £2 per divine op-amp ! Wonder what Doc Martin would have to say;?... You lost me Graham |
Amplifier power
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. Graham |
Amplifier power
GregS wrote: Eeyore wrote: Rob wrote: Eeyore wrote: Once only wrote: wrote in message If all (properly designed) amps sound the same, how do I decide which amp to buy? Is it just a case of choosing one with sufficient power output and how do I determine this? No, thats not true - the myth of long wire with gain. Amplifiers can have very similar specs but have different sonic characters and abilities. Bandwidth and an amps ability to pump out the amperes when fronted with an awkward load etc etc etc. If I were you the first thing is to not pay too much attention to the big girls blouses of this group. Do yourself a favour, don't heed mag reviewers advice either. Try the pre-owned market, plenty of stereo bargains to be had. This is just one example, the Pioneer A400 was a huge success because of it ultra wide stable bandwidth (5 - 100) and it's impressive ability to drive any loudspeaker and remain stable - thats the ability to churn out amperes! It sold by the truck load and often crops up in the for sale ads, and it is proven to be a rugged longstander, can be picked up for less than £100. But then there are others, Nad, and even Sony from the late 80's and early 90's. First port of call believe it or not would be Cash Converters, then the specialist pre-owned dealers, then the small ads. Once you've found a model, look it up! Don't bother with Naim or Arcam, over-priced and nothing special. But don't buy antiques. No matter how well they were supposed to sound. All the electrolytic caps will need replacing and standards weren't as high then. Modern amplifiers are much better on the whole. cross-posted intentionally to rec.audio tech I have a 20 year old (at least) NAD 3020 - works perfectly but sounds distinctly soft/mellow compared to a newish SS amp, and indeed an even older Pioneer receiver. Is this a symptom of old caps, and/or poor design? I know the 3020 moderately well. It was very well regarded (and designed - I fact I met the designer) and should still sound at least decent today. At that age, recapping the electrolytic caps specifically is likely to be a good move. Especially if you're competent with a soldering iron yourself or have a friend who is. The parts won't cost much. I have gone over many amps, and its really rare that I would need to replace the main caps. Many times the smaller caps will go bad. If I were really going over an amp in every detail, if I had plenty of time, then I might check the main caps, or even buffer them. Its likely an amp will sound just fine if not driven hard with lossy main caps. If it can obtain max power with resonable distortion then I would not touch the main caps. I'd avoid over over-generalising. The lifetime / ripple current rating etc of reservoir caps varies hugely. Any sign of a bulge or white/yellow deposits around the base and out it comes. Graham |
Amplifier power
In article ,
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 |
Amplifier power
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Amplifier power
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Amplifier power
"Eeyore" wrote ...
tony sayer wrote: Eeyore scribeth thus Did you check the spec of the LME49720 ? http://www.national.com/pf/LM/LME49720.html They had to devise a special method to measure the THD without the noise dominating. They're not even that shockingly expensive. Shockingly enough in small quantities;!... From the likes of Farnell maybe £4 seems a lot but compare that to a $400 wooden volume control knob ! http://uk.farnell.com/1367613/semico...questid=131459 That's only £2 per divine op-amp ! I can't remember the last time (or ever?) I've seen a chip that was concurrently available in a package as new as SOIC and still in an antique metal-can, 8-pin TO-99! Is there some sort of continuing demand for those old metal cans? Military? |
Amplifier power
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 |
Amplifier power
Richard Crowley wrote: "Eeyore" wrote ... tony sayer wrote: Eeyore scribeth thus Did you check the spec of the LME49720 ? http://www.national.com/pf/LM/LME49720.html They had to devise a special method to measure the THD without the noise dominating. They're not even that shockingly expensive. Shockingly enough in small quantities;!... From the likes of Farnell maybe £4 seems a lot but compare that to a $400 wooden volume control knob ! http://uk.farnell.com/1367613/semico...questid=131459 That's only £2 per divine op-amp ! I can't remember the last time (or ever?) I've seen a chip that was concurrently available in a package as new as SOIC and still in an antique metal-can, 8-pin TO-99! Is there some sort of continuing demand for those old metal cans? Military? Audiophools ? Graham |
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