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Old 19th October 2013, 08:03 PM   #10601
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It was . I found it by prodding around . The R10 symbol is set between the resistors and is obvious once tested . In real life much smaller . 390 mV does some nice things ( 1.34 V standard into 100 K ) . It suits NE5532 better for a start which was born out by some tests . Hypex use 100 R series resistance input to chip .

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Old 20th October 2013, 06:11 PM   #10602
dvv is offline dvv  Serbia
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Nige, I may be missing the point, but I would wager that a high quality standard analog PSU would outshine soundwise the vast majority of SPSs. They may be much less effcicient, but there's no such thing as a free lunch, and efficiency has its price.

Put in another way, if you could separate the input stage/VAS power supply on those boards, and feed them from fully regulated and well filtered separate lines from those feeding the current stage, 1 will get 10 you'd have a much better sound.

11 years ago, a friend and I measured the amount of noise those switchmode power supplies as used in PCs send back into the grid - "criminal" is the only word applicable. They should be outlawed. And all it takes is one simple capacitor to cut the problem down by 90%, yet only ONE PSU had it.

I would imagine the switchmode supplies for audio are in fact better made, but in my book, they still have a long way to go - a VERY long way. And when they make it, they will cost as much as standard supplies, their only benefit being that they will be much smaller and hence need less in-case real estate.
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Old 20th October 2013, 08:18 PM   #10603
gootee is offline gootee  United States
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This is interesting. It has a chart of the power needed to match the SPL of instruments, for different speaker sensitivities. I still need to translate it from the French, to better-understand it.

(a.wayne, you might have been shooting way too low, with your lust for power. <grin> )

Capacit dynamique d'un systme audio
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Old 20th October 2013, 08:32 PM   #10604
benb is offline benb  United States
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There's always Google Translate which may be useful, though it doesn't translate the text embedded in images: Google Translate
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Old 20th October 2013, 11:19 PM   #10605
fas42 is online now fas42  Australia
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Thanks for that, Tom. Some interesting points ... note that the piano, supposedly so difficult to do, only requires a 60W amp to drive speakers of typical efficiencies, 90dB, to maximum loudness. Which matches up with my own experience - a solo piano requires the volume to be such that the amp is at the point of clipping on a peak transient, essentially the max. volume setting on the HT system.

The most extreme volumes are only for people wanting to do silly things, like sitting a foot in front of the brass section in a full size orchestra - low 120dBs is a good goal, will take care of 99.9999% of situations ...
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Old 20th October 2013, 11:24 PM   #10606
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Quote:
Originally Posted by dvv View Post
11 years ago, a friend and I measured the amount of noise those switchmode power supplies as used in PCs send back into the grid - "criminal" is the only word applicable. They should be outlawed. And all it takes is one simple capacitor to cut the problem down by 90%, yet only ONE PSU had it.
I'd steer away from SMPSUs for PCs in any audio application, they really are built down to the lowest possible price. Digital stuff has higher noise immunity so low output ripple isn't a major requirement. Didn't they have to meet any regulations for conductive noise?

Quote:
I would imagine the switchmode supplies for audio are in fact better made, but in my book, they still have a long way to go - a VERY long way. And when they make it, they will cost as much as standard supplies, their only benefit being that they will be much smaller and hence need less in-case real estate.
Switchers built specifically for audio I've yet to encounter - my experience has been with the general purpose brick kinds (Meanwell, from Taiwan and 50% cheaper mainland Chinese clones of these with no regulatory approval). Yes they're not suitable for audio in stock form, but can be modded. The grounding (internal caps between mains and the output 0V) needs attention. Output ripple needs filtering (too much HF hash), common-mode noise needs suppressing. Provided you take steps to address these, I'd never go back to an ordinary linear supply. SMPSUs are definitely the future for audio poweramps.
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Old 21st October 2013, 04:11 AM   #10607
a.wayne is offline a.wayne  United States
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Quote:
Originally Posted by gootee View Post
This is interesting. It has a chart of the power needed to match the SPL of instruments, for different speaker sensitivities. I still need to translate it from the French, to better-understand it.

(a.wayne, you might have been shooting way too low, with your lust for power. <grin> )

Capacit dynamique d'un systme audio

No underestimation here , big speakers and lots of power for any sort of realism



Quote:
Originally Posted by fas42 View Post
Thanks for that, Tom. Some interesting points ... note that the piano, supposedly so difficult to do, only requires a 60W amp to drive speakers of typical efficiencies, 90dB, to maximum loudness. Which matches up with my own experience - a solo piano requires the volume to be such that the amp is at the point of clipping on a peak transient, essentially the max. volume setting on the HT system.

The most extreme volumes are only for people wanting to do silly things, like sitting a foot in front of the brass section in a full size orchestra - low 120dBs is a good goal, will take care of 99.9999% of situations ...
Not so that estimation is for a listening distance of 1M, flea power and high sensitivity can make for real noise , not so for realism and size , big power wins out all the time ....
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Old 21st October 2013, 05:03 AM   #10608
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I've a feeling the combination of realism, size and big power you're talking about here is the impression that the bottom end of the keyboard is being fully expressed, realised ...

Talking about distances from speakers, this for me is always a key indicator: when the sound not up to scratch, the distance you are from the drivers is crucial, makes all the difference; when in good order, that distance becomes irrelevant - you can be 1m, 2m, 4m ... or just 0.5m away ... makes no difference, subjectively ...
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Old 21st October 2013, 07:47 AM   #10609
dvv is offline dvv  Serbia
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Quote:
Originally Posted by gootee View Post
This is interesting. It has a chart of the power needed to match the SPL of instruments, for different speaker sensitivities. I still need to translate it from the French, to better-understand it.

(a.wayne, you might have been shooting way too low, with your lust for power. <grin> )

Capacit dynamique d'un systme audio
Very interesting indeed. For me especially.

It MIGHT have a caveat - those are pure numbers, "as is" in real life, but I have yet to hear a recording on any medium which did not compress the original sound at least a wee little bit.

This table clearly shows that with my speakers, and the power I am mostly concerned with, I am just fine with my own take on a 100W/8 Ohm amp. One of the reasons for this is that given the power supply voltages, my 100W amp will not clip up to about 172W/8 Ohms, an additional +2.3 dBW not everyone has.

It also VERY clerly shows that what Klipsch, JBL, Altec Lansing and me have been saying all along - speaker efficiency is GOOD! The least efficient speakers I have ever had were my AR 5 boxes - typical AR of the day (early 70ies), superb tonal balance, but at 87 dB/1W/1m, not efficient enough. It drained my reVox A78 integrated amp (rated at 50W/8 Ohms) of the day at any higher volume level.

Lastly, the table shows the absolute numbers, but let's not forget that at home, in our rooms, we do not listen in absolute numbers. As Wayne put it, 85 dB SPL in a room is already quite loud, but still within our comfort zone, and will not cause the SWAT team to come crashing in through the door. Or the missus to reach for her kitchen cutlery.
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Old 21st October 2013, 07:58 AM   #10610
dvv is offline dvv  Serbia
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Quote:
Originally Posted by abraxalito View Post
I'd steer away from SMPSUs for PCs in any audio application, they really are built down to the lowest possible price. Digital stuff has higher noise immunity so low output ripple isn't a major requirement. Didn't they have to meet any regulations for conductive noise?

Switchers built specifically for audio I've yet to encounter - my experience has been with the general purpose brick kinds (Meanwell, from Taiwan and 50% cheaper mainland Chinese clones of these with no regulatory approval). Yes they're not suitable for audio in stock form, but can be modded. The grounding (internal caps between mains and the output 0V) needs attention. Output ripple needs filtering (too much HF hash), common-mode noise needs suppressing. Provided you take steps to address these, I'd never go back to an ordinary linear supply. SMPSUs are definitely the future for audio poweramps.
I understand a British company, Chord, uses them in their amps, however, this one is of their own design and manufacture, not likely to appear anywhere.

While I quite agree with your note on tuning a switchmode PSU, and while I have indeed dome some of this myself in my time (replacing suspect 150uF electrolytics with quality Siemens 330 uF, replacing some god-knows-which-if-even-He power transistors rated at 90 and 120 Watts with 200 Watt Motorola trannies, etc), I still have to say it - when you have just bought it, and know straight away it needs work, something is awfully wrong with the industry. My filters will make sure the junk from the grid never gets into it, but there's nothing they an do about poor, cheapskate parts used inside, with corresponding results.
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