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Old 19th March 2012, 06:10 AM   #3721
gootee is offline gootee  United States
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And if your power/gnd rails are more than a couple of inches long, in a power amp you will want to have big-enough decoupling capacitors very close to the point-of-load (each of the output devices).

Cheers,

Tom
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Old 19th March 2012, 07:43 AM   #3722
dvv is offline dvv  Serbia
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Quote:
Originally Posted by a.wayne View Post
Batteries ....! Dead sound ..........
Batteries, like everything else, have their pros and cons. On the one hand, they are as near to perfect DC as we can come, which is a definite plus. But they are slow, much slower than most electronic ciruits, and are thus not well suited to anything that has sudden large voltage/current swings, such as power amplifiers.

Stax had a 100 wrms out-of-this-world power amp, which was on a cart, and another cart moved around its impressive set of batteries, weighing in at over 100 kilos ( > 220 lbs). The inital series was fed straight from the batteries (don't ask me how) and returned dead as a doornail sound. This was quickly rectified by adding an electronic regulation circuit between the batteries and the amp, after which it turned into a legend in Japan. Unfortunately, as all things Stax, while meade in state of the art mode, its price was sheer astronomy, around Jupiter, I think, so few were made.

These days, batteries are used to power Nagra's tube preamp, but not the power amp. Both cost an arm and a leg.

I should have the service schematic of the above Stax amp, if anyone is interested, I can either post it, or e-mail it.
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Old 19th March 2012, 07:55 AM   #3723
dvv is offline dvv  Serbia
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Quote:
Originally Posted by cliffforrest View Post
@dvv

" I hope there is no-one here who believes that powwer transformers are not stressed by line hash. When they start humming is only the last stage, by that time, you have a catastrophe on your hands."

What on earth is that all about??

You must be drinking something very different to me

edit: didn't see Abraxalito's comment
As is, a transformer hums when power is applied, the sound is reasonable but strictly 2D. Add a filter, no humming, and the soundstage acquires some distinct 3D features.

Measure S/N ratios as is, add a power filter, and measure again - better.

For what's in the grid, simply connect an oscilloscope and take a peek. You WILL be surprised, although I must add that this does vary quite a bit depending on your location. If the local power transformer is next to your home, the benfits will be smaller, but increaseing the further away you are.

Especially effective in densly populated areas, such as big cities.

Especially effective for tube audio, which seems to benefit the most. As for why, that you need to ask the designers.

A 50:50 proposition for amps with power regulation. Works very well with older Naim gear, but not impressive with new Naim gear; I have heard it literally transform two all Krell systems from mundane to outstanding, and big Krell FPB amps have several regulation circuits inside. You never know, the only way to really know is to try it and see/hear.

THAT'S the bugbear of all power line electronics - manufacturers advertise as if they were selling a ticket to paradise, which can happen, but is by no means guaranteed to be so. Again - the only way to KNOW is to try them.
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Old 19th March 2012, 08:01 AM   #3724
Previously: Kuei Yang Wang
 
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Hi,

Quote:
Originally Posted by dvv View Post
These days, batteries are used to power Nagra's tube preamp
Correction, a switched mode supply powers the Nagra Tube Pre. The Batteries power that.

I have used battery powered solid state before. It does have it's distinct advantages, but practicality is low. Since I have investigated power supplies more to get closer to batteries without needing them.

Ciao T
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Old 19th March 2012, 08:05 AM   #3725
Previously: Kuei Yang Wang
 
Join Date: Nov 2002
Hi,

Quote:
Originally Posted by dvv View Post
As is, a transformer hums when power is applied, the sound is reasonable but strictly 2D. Add a filter, no humming, and the soundstage acquires some distinct 3D features.
The problem in this case is DC offset on the mains. All gear of mine (at home) and all I design includes as an ABSOLUTE MINIMUM the DC blocker and a snubber across the mains to kill the mains inductance.

I normally prefer to build the filtering into the transformer, where I cannot do that sufficiently, I used heavily overrated LC filters with corner frequencies as low as I can find. The NEC-Tokin Filter I picked for my poweramp has a 30KHz corner and the size of a big electrolytic cap... It will be combined with 68,000uF cap as DC blocker...

Ciao T
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Old 19th March 2012, 08:08 AM   #3726
dvv is offline dvv  Serbia
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Quote:
Originally Posted by abraxalito View Post
I'm curious - what is the hash here? Stuff in the 10kHz - 100kHz band from SMPSUs? If such high frequency then how might it stress the transformer? Doesn't the transformer look like a big lossy inductor to the mains supply? Is your meaning of 'stress' increasing the flux in the core much closer to, or even into, saturation?
In my view, about 98% of what should not be there but is lies in the 20 - 80,000 Hz range. Mostly fundamentals from various devices and their harmonics.

Manufacturers often quote cell and wireless phones, radio and TV - while they all do have their share, what is often too lightly passed over is that their relative POWER ratio is very low, especially compared to such devices as washing machines, hot water boilers, etc. I am not saying they are not a problem, I am saying they are much less of problem than they are made out to be.

Which explains why simple, IEC socket installed, power line filters do next to nothing - they have their -3 dB cutoff point at around 600 kHz, by which time 98% of the hash has already gone inside.

Attach a temperature proble to a power transformer. Measure temp under normal operating conditions as is, then insert a filter, and measure again. Lower, not astonishingly so (as some would have you believe), but 3-5 degrees could happen easily.

As for voltages, with any luck, you will see peaks in the range of 600-900 Volts, all very short of course, typically less than 1 mS.

Try some of what I pointed out, and we can discuss it. I am used to people not believeing what's going on in the grid, so until you see it for yourself, there's no point in discussing it. Or, if you do wish to discuss the point further, move it to the private message region, else I'll be accused of misusing the forum to sell.
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Old 19th March 2012, 08:14 AM   #3727
dvv is offline dvv  Serbia
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Quote:
Originally Posted by ThorstenL View Post
Hi,



Correction, a switched mode supply powers the Nagra Tube Pre. The Batteries power that.

I have used battery powered solid state before. It does have it's distinct advantages, but practicality is low. Since I have investigated power supplies more to get closer to batteries without needing them.

Ciao T
Point taken, but in real world terms, it's a small difference. The original power source is still a battery, a near perfect DC source. Whatever you do to it afterwards will not improve it, just change it.

Agreed on the disasterously low practicality factor. Simply put, they are cumbersome, expensive and fidgety. You're much better off investing the money and real estate inside a device on classic supplies, but done right.
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Old 19th March 2012, 08:30 AM   #3728
dvv is offline dvv  Serbia
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Quote:
Originally Posted by ThorstenL View Post
Hi,



The problem in this case is DC offset on the mains. All gear of mine (at home) and all I design includes as an ABSOLUTE MINIMUM the DC blocker and a snubber across the mains to kill the mains inductance.

I normally prefer to build the filtering into the transformer, where I cannot do that sufficiently, I used heavily overrated LC filters with corner frequencies as low as I can find. The NEC-Tokin Filter I picked for my poweramp has a 30KHz corner and the size of a big electrolytic cap... It will be combined with 68,000uF cap as DC blocker...

Ciao T
Thorsten, from our discussions way back, I know you pay much attention to your power supplies. You have realized that power is to a circuit what our blood is to us - you can't expect a man with heart problems to run a marathon.

What you have to understand that you are THE minority. It often surprises me how flippant about power sources the mainstream industry is. The logic seems to be - what the hell, just throw in two medium sized caps which don't cost too much, and that's it. What? We have 5 100 wrms channels inside? OK, then don't use a pair of 6,800 uF caps, use a pair of 8,200 uF caps.

End result - if you want some serious oomph from your subwoofer, you have to get a self-powered one.

If anything has distinctly DEGRADED in the mainstream audio since the 70ies, those would be the power supplies. Just take a look at the Pioneers, Kenwoods, Sonys and the rest of them in the 70ies and compare them with similar products today.

In those days, products like Sansui's 2x85 wrms amps had at least 80,000 uF in front of them, often from separate left and right power transformers of rather good quality; today, if you find 30,000 uF in a similar product, you are one lucky man.

Some, notably the Brits (Naim, Cyrus, etc), will offer you add-on power supplies which will improve your sound - but by the time you have your end price, you discover you would have been better off buying a say Accuphase and having it all inside just one case. As I see it, they are charging you extra for what should have been there in the first place.

One of my two gripes about H/K gear is what I feel are their undersized filter caps. They get the numer right, they get the power transformer size right, but
they somewhow always undersize them by at least one step, usually two or three. Where they put in 8,200 uF, I would have put in at least 10,000 uF, more probably 12,000 or even 15,000 uF.

But, of course, they have price limits they must satisfy, and these by deafult come before the quality consideratons.
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Old 19th March 2012, 08:47 AM   #3729
Previously: Kuei Yang Wang
 
Join Date: Nov 2002
Hi,

Quote:
Originally Posted by dvv View Post
Point taken, but in real world terms, it's a small difference. The original power source is still a battery, a near perfect DC source. Whatever you do to it afterwards will not improve it, just change it.
Well, what is done in this case is to turn into a near perfect squarewave, send it through a stepup transformer/inductor and then rectify it. To me this would suggest defeating all the key benefits of the battery...

Quote:
Originally Posted by dvv View Post
Thorsten, from our discussions way back, I know you pay much attention to your power supplies. You have realized that power is to a circuit what our blood is to us - you can't expect a man with heart problems to run a marathon.

What you have to understand that you are THE minority.
Oh no, I understand this all too well. When AMR eventually gets around to it, we will re-package all the mains side technology we build into our 77 series Products and make them into a standalone conditioner... But we are currently working on other stuff...

We still have to work out the unique angle's and selling points (that is the marketing side).

The fun part is that practically every dealer and distributor has found that AMR gear most of the time sound best straight into the wall, no filters, expensive distribution etc...

I remember one very upset customer when I told him what degraded the sound of his system (AMR Phono, CD-Player and Monblocked Amp's) was his very expensive power conditioner. In the end the only that sounded better plugged into that conditioner rather than straight into the wall was his Turntable!

I suspect that if every manufacturer did what AMR do on the powersupply side (the actual cost is fairly notional, at least in a high end product) you'd be out of the mains conditioner business...

Ciao T
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Old 19th March 2012, 08:55 AM   #3730
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Originally Posted by scott wurcer View Post
I forgot to mention Bob Ludwig, as another name well represented by great LP's. You must have folks like this on your side of the ocean that we never hear of.
I, personally, am not aware of any of the similar calibre.

Btw, if anyone knows decent cutting house in Europe, please let me know or PM me with contact details, as I'm looking for one.
By "decent" I mean one, that has its signal chain free of unnecessary cabling/electronics and what else and that don't use A-820/A-80VU/A-80RC machines with their stock playback electronics. C-37 also doesn't count due to mechanical reasons. Plus they should be specialists in their field as well.
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