You are here

Log in or register to post comments
ethanwiner
ethanwiner's picture
Offline
Last seen: Never ago
Joined: Sep 1 2005 - 2:26pm
Re: Clean Power


Quote:
I was hoping to travel light


Yeah, after I wrote that it occurred to me a power conditioner is not something that's easy to carry on a train. Hey, just having you visit will be fabulous all by itself.

Also, I didn't really intend for our visit to be a bunch of gear tests! I have lots of fun stuff here, and I'd rather play with the toys and do "normal" listening anyway. And chat more generally about audio stuff - and acoustics of course!

--Ethan

ethanwiner
ethanwiner's picture
Offline
Last seen: Never ago
Joined: Sep 1 2005 - 2:26pm
Re: Clean Power


Quote:
amps are merly modulated power supplys.


Good point. A power amp converts the incoming AC power line to filtered DC, and modulates that with the audio being amplified. So proper power line filtering is already an integral duty of a power amp.


Quote:
How come Crown, QSC, numerous ohter units keep cranking and cranking all nite long under teh most insane conditions, low line voltages, high line voltages, dips, spikes etc. And the majority of em just keep on going. And they sound just fine.


Indeed. I never understood why audiophile purists look any farther than professional grade equipment. The good ones measure and sound great, and are built like tanks, and cost a lot less than the boutique stuff which, as you pointed out, is often frail and blows up too easily.

--Ethan

Elk
Elk's picture
Offline
Last seen: 5 months 4 days ago
Joined: Dec 26 2006 - 6:32am
Re: Clean Power

Ergonaut,

Are you saying that your amplifiers have power supplies that have no ripple, etc.? How expensive are such power supplies? Can you provide us with examples of of equipment (CDP's, preamps, amplifiers, etc.) that have such power supplies?

AS an example, Levinson equipment often incorporates inernal AC power regeneration in which the DC supply is derived from an AC source generated within the device itself. Very cool, effective, but very expensive.

I hope this doesn't sound argumentative, it isn't meant to be. I am absolutely certain that it is more than possible to build power supplies of such quality, but I would expect them to cost quite a bit and to be too expensive to be present in reasonably priced equipment.

I ask because from my limited experience, the DC that is output from a rectifier is not perfect. The junk in the incoming AC is greatly reduced but still reflected in the outgoing DC. These imperfections power the downstream circuits and could negatively impact the sound.

Even if the incoming AC is perfect, the DC output can be less than perfect. For example, the unfiltered output from a rectifier varies in voltage. The purpose of the filter capacitor on the DC output of the rectifier is to filter the output to produce constant voltage DC. However, even after the filtering capacitor or smoothing circuit there typically remains some voltage ripple. Wouldn't this negatively impact the sound

dbowker
dbowker's picture
Offline
Last seen: 2 months 3 weeks ago
Joined: May 8 2007 - 6:37am
Re: Clean Power

All good points (mostly) people, but actually this thread wasn't even about Power Conditioning, nor was my conclusion isolated to what a dedicated line did for my amp. For all I know, it did nothing for the amp, given it's build and beefy power supply, but the noise removal took place all on the front end! Maybe all the added detail I'm getting is happening for the CD player and my phono preamp? Don't know, and only sort of care. My point was, for a mere $300 investment of having an electrician do a quality job of giving my system of it's own 20 amp circuit and isolated ground I got a easily observable and very satisfying drop in noise, and thus more music comes through. Dats all there is too it folks! Nothing fancy, just good clean(er) power.

Ergonaut
Ergonaut's picture
Offline
Last seen: Never ago
Joined: Apr 15 2007 - 9:01am
Re: Clean Power


Quote:
Nothing fancy, just good clean(er) power.

Good thing to have

Ergonaut
Ergonaut's picture
Offline
Last seen: Never ago
Joined: Apr 15 2007 - 9:01am
Re: Clean Power


Quote:
Ergonaut,
Hi ELK
Are you saying that your amplifiers have power supplies that have no ripple, etc.? How expensive are such power supplies? Can you provide us with examples of of equipment (CDP's, preamps, amplifiers, etc.) that have such power supplies?


One can design to reject as much ripple as possible - there is a lot more available quality components today, compared to say the 1970's and 1980's --

My preference (and I am doing 120W into 8 Ohm mono-blocs right now) is to design an amplifier with a power supply holding 10x the muscle than the amplifier actually needs. i.e. For Stereophile purposes and my own self build, for every 100 Watts I will provide the amplifier with a supply that would with ease provide power for a 1000 watt amplifier.

The reason for this over engineering is to mitigate certain inherent issues. Ripple, rail noise and instability becomes more apparent the closer you get to the power supplies limit.

So If I design so those limits cannot be reached - This puts me in the camp of the "Over Engineer".

This isnt the most refined way of designing an amplifier. Naim, Musical Fidelity, Roksan and Carver dont do it this way - Krell, Mark Levinson, Bryston do. Hence why their Chassis wouldnt look out of place on 4 huge legs drilling for oil.

I am re-arranging my lab right now and I'm going to take some shots of the design and build as it journeys through it phases of development-- Then I'll show test examples such as this and what you can expect to see.

cyclebrain
cyclebrain's picture
Offline
Last seen: 2 years 7 months ago
Joined: Jun 16 2006 - 11:40pm
Re: Clean Power

I too was suprised when designing my amplifier. I wanted to use a power transformer with a power rating greater than the sum of the max power output of both channels divided by the effiency of the amplifier. Even using highly efficent switching amps I was suprised of the huge size of transformer required. Much larger than used with a higher powered, less efficent class AB amp.

trevort
trevort's picture
Offline
Last seen: 3 years 8 months ago
Joined: Aug 21 2007 - 8:05am
Re: Clean Power

Followed up on your endorsement for a dedicated power line.
Hooked up with an electrician who can do the job.
He showed some astonishment when I mentioned 20A line, saying I could run half my house on it.
Before proceeding, wanted to get sense of whether I really need that much current.
I'm pretty low volume sort of listener.
Power amp is 80 Watts / Channel. If this is my main drain on power, Its hard to see how my 4 or so components could draw even 10 Watts.
Of course, its no big deal to put in an oversized line, but if your 20A line was because of your particular situation, no need to install that much copper myself.

What size of dedicated power line would be appropriate for a reasonably modest system, as described above or even 2X that power, in case of eventual upgrade?

tx
t

CECE
CECE's picture
Offline
Last seen: Never ago
Joined: Sep 17 2005 - 8:16am
Re: Clean Power

15A ckts are fine for home audio stuff. Actually running consumer amps on 20A protected lines is kinda dumb, since most line cords are 16 guage maybe 14g for higher powered amps.....The NEC rule is 80% of continuous current, continuous use is 3 hours and more. A 15A ckt just for your stereo would be fine. With nothing else on it. I run 3 15A ckts to power up my stuff, the entire system when cranking takes about 18A at 105dB or so...with some serious bass. I know it does cus the Furmans have front panel voltage and current read outs. I also have 4 mono amps running which are about 1400+ W RMS capable, they draw a considerable amount of current when cranking. So I divided it among 3 ckts, to not pop the breakers. Nothing else is on them but the audio stuff...an 80W amplifier really doesn't need it's own line...that is less than a big screen tv

dbowker
dbowker's picture
Offline
Last seen: 2 months 3 weeks ago
Joined: May 8 2007 - 6:37am
Re: Clean Power

Yeah, DUP's right. For what you have you don't need the 20 amp circuit. Maybe I went overboard but I'm using a class A amp that draws around 300 watts normally and can peak to far more than that and I figured why not? It was some effort to get he line routed to that place in the room, and this way I've got plenty of juice to spare for the future if I need more.

Elk
Elk's picture
Offline
Last seen: 5 months 4 days ago
Joined: Dec 26 2006 - 6:32am
Re: Clean Power

Extra headroom is always a good thing - especially when it doesn't cost much more.

Good call.

trevort
trevort's picture
Offline
Last seen: 3 years 8 months ago
Joined: Aug 21 2007 - 8:05am
Re: Clean Power

Thanks all.
15A sounds fine -- there's no way I'd ever survive 105db!
Incidentally, its not for the unfettered current flow I perked up when I saw this post about a dedicated line.

I'm mostly looking to have a line that doesn't pick up the buzz from my rheostically dimmed lights -- an obvious loud and annoying sound -- as well as perhaps pre-empting the other lesser invasions mentioned in this thread.

cyclebrain
cyclebrain's picture
Offline
Last seen: 2 years 7 months ago
Joined: Jun 16 2006 - 11:40pm
Re: Clean Power


Quote:
I too was suprised when designing my amplifier. I wanted to use a power transformer with a power rating greater than the sum of the max power output of both channels divided by the effiency of the amplifier. Even using highly efficent switching amps I was suprised of the huge size of transformer required. Much larger than used with a higher powered, less efficent class AB amp.

While I noticed that my math was wrong, I still question the small size of power supplies relative to max output power and amplifier efficiency. Feedback Ergo?

Ergonaut
Ergonaut's picture
Offline
Last seen: Never ago
Joined: Apr 15 2007 - 9:01am
Re: Clean Power


Quote:

Quote:
I too was suprised when designing my amplifier. I wanted to use a power transformer with a power rating greater than the sum of the max power output of both channels divided by the effiency of the amplifier. Even using highly efficent switching amps I was suprised of the huge size of transformer required. Much larger than used with a higher powered, less efficent class AB amp.

While I noticed that my math was wrong, I still question the small size of power supplies relative to max output power and amplifier efficiency. Feedback Ergo?

Hi Cycle

Oooops -- I missed this -- woz it meh you wished to feed back?

SHREEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEK

Oh sorry - not that type of feedback

I dont think you were wrong -

The Big PA - Concert Amplifier people usually say "design for power then add a third extra in the power supply for headroom"

And I kind of agree to this approach in Audiophilia

If you have a lot of Amplifier and hardly any supply -- that leads to cheap audio (Try Car Audio as an example and PWM Amplifiers)

If you have an Amplifier with the correct supply balanced against power out - you will have adequate capability but not much elasticity or headroom.

I go for having a small amplifier (In relative terms) and a power supply the amplifier hasnt the capability to interupt or cause any of the usual ill effects from not having enough OOoomph.

PWM (Pulse Width Modulated) Amplifers, Which are essentially the audio equivalent of "Switch Mode power supplies" are IMO a disaster. I just dont like them - but that is a personal/engineering dislike.

Pages

  • X
    Enter your Stereophile.com username.
    Enter the password that accompanies your username.
    Loading