U.P.S. (Uninterrupted Power Supply)

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Re: U.P.S. (Uninterrupted Power Supply)

Postby Ernie » Tue Aug 23, 2005 12:36 pm

ihatejazz wrote:Contrary to rumors from audio gurus a U.P.S. did not, in any way, dteriorate the sound of my system. In fact I honestly felt that the sound improved tremendously. Background much quieter and full of detail and life in the music.

This is my first salvo using the unpopular device which most of our audio hotshots frown upon. What have I got to lose? To my satisfaction I am buying this 600watt capacity unit for sole use of my Clearaudio Balanced Reference phonostage which I don't intend to turn off and want it on even during brownouts. I will be buying two units of 1.25kva for my power amps.


Where can we purchase this ups unit. Thanks!
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Postby tonydog » Tue Aug 23, 2005 11:59 pm

I have a very good conditioner and AVR from Master Rivo. I saw how it worked yesterday during a massive lightning storm. The breaker shutdown and doesn't turn on untill you press the reset button. W/out that feature i think some fuses would have been fried or maybe worse.

How does the UPS protect in this situation?
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Postby JackD201 » Mon Sep 05, 2005 12:34 pm

Mods Moz or Hyperion please move a copy to Tech Archive.

Thanks,

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Re: U.P.S. (Uninterrupted Power Supply)

Postby leo » Thu Nov 10, 2005 3:06 am

ihatejazz wrote:Contrary to rumors from audio gurus a U.P.S. did not, in any way, dteriorate the sound of my system. In fact I honestly felt that the sound improved tremendously. Background much quieter and full of detail and life in the music.

This is my first salvo using the unpopular device which most of our audio hotshots frown upon. What have I got to lose? To my satisfaction I am buying this 600watt capacity unit for sole use of my Clearaudio Balanced Reference phonostage which I don't intend to turn off and want it on even during brownouts. I will be buying two units of 1.25kva for my power amps.


I have one concern though.

These UPSes, whether the Backup type or the SMART ones, have indications of current ratings on their output ports ranging from 2.5 to 3.5 amperes only.

Audio gears, most specially amplifiers, would often require more current. What would be the effect of this on such audio gears then? Would it be harmful to the equipment's circuitry?
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Re: U.P.S. (Uninterrupted Power Supply)

Postby rascal101 » Thu Nov 10, 2005 1:31 pm

leo wrote:I have one concern though.

These UPSes, whether the Backup type or the SMART ones, have indications of current ratings on their output ports ranging from 2.5 to 3.5 amperes only.

Audio gears, most specially amplifiers, would often require more current. What would be the effect of this on such audio gears then? Would it be harmful to the equipment's circuitry?


You can calculate the amount of current your amplifier needs. For example,

Given:
amplifier output power = 10W per channel
input line voltage = 220V

Solution:
total output power = 10*2 = 20W
linear power supply efficiency = 50% (assumed typical)
power factor = 0.5 (assumed typical)

Efficiency = tot output power / (power factor x input power)
input power = tot output power / (power factor x Efficiency)

= 20/(.5 x .5) = 80watts

input power = input line voltage x input line current
input line current = input line voltage / input power

= 220/80 = 2.75A

Note: the linear power supply typically used in audio is really bad in terms of efficiency. So much converted to waste.

In a typical circuit, if the devices require 10A but only power supply can supply 8A or less, supply voltage (rail to rail) will go down. The power supply will try its best to give the 10A. When it does, supply voltage will go down (to maintain input power). As such, peak signal can easily reach supply voltage (since its lower) causing clipping. I don't know how this sounds as I haven't heard one yet but I guess sound will be bad.

Cheers,

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Postby Oldfogey » Thu Nov 10, 2005 2:37 pm

Hi rascal,

I tried using your formula, but something doesn't seem to be right. Maybe my math is really bad :)

My flea power amp produces 2.5 watts per channel. Using the formula, is it correct that my amps need 11 amps of current? :?

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Re: U.P.S. (Uninterrupted Power Supply)

Postby zenaudio » Thu Nov 10, 2005 4:31 pm

rascal101 wrote:
input power = input line voltage x input line current
input line current = input line voltage / input power

= 220/80 = 2.75A



There's something wrong in the above derivation

For an easy guide, go to

http://www.sengpielaudio.com/calculator-ohm
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Postby Oldfogey » Thu Nov 10, 2005 5:18 pm

zenaudio,

Thanks for the link! Did the calculations, and my amplifiers need 0.011 amps of current. That's more like it :D

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Postby Guest » Thu Nov 10, 2005 5:20 pm

Oldfogey, Zenaudio,

The substitution is wrong (my mistake),

input power = input line voltage x input line current ---> correct <----
input line current = input line voltage / input power ---> wrong <---

input line current = input power / input line voltage ---> corrected <---
for my example;

= 80/220 = 0.36A or 360mA

for your case

= 20/220 = 0.1A or 100mA

Thank you for pointing it out.

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Re: U.P.S. (Uninterrupted Power Supply)

Postby leo » Thu Nov 10, 2005 9:03 pm

rascal101 wrote:

Given:
amplifier output power = 10W per channel
input line voltage = 220V

Solution:
total output power = 10*2 = 20W
linear power supply efficiency = 50% (assumed typical)
power factor = 0.5 (assumed typical)

Efficiency = tot output power / (power factor x input power)
input power = tot output power / (power factor x Efficiency)

= 20/(.5 x .5) = 80watts

input power = input line voltage x input line current
input line current = input line voltage / input power

= 220/80 = 2.75A

Note: the linear power supply typically used in audio is really bad in terms of efficiency. So much converted to waste.

In a typical circuit, if the devices require 10A but only power supply can supply 8A or less, supply voltage (rail to rail) will go down. The power supply will try its best to give the 10A. When it does, supply voltage will go down (to maintain input power). As such, peak signal can easily reach supply voltage (since its lower) causing clipping. I don't know how this sounds as I haven't heard one yet but I guess sound will be bad.

Cheers,

Rascal101



Thank you for your input.

Does this formula work for integrated amps that are dual mono?

The integrated amp is dual mono and the gear is rated as 70W/8Ohms, 110W/4Ohms, 220 volts, 20amp Peak Current.

I plugged it to a APC Backup UPS rated at 400 watts capacity with output ports of 3.0 amperes.

I noticed that the entire audio system (CD and Amp) sounded well when plugged into the UPS. Although not in a very big way but noticable enough as the system became clean sounding, more detail, firm bass, and the harshness at high frequencies seems to have soften.

It seems okay now but I'm wondering though if I'm doing harm to my amplifier in the long run.

Do you think I'm starving it of its "current" requirement?

Maybe I'm just being paranoid. = >

Could you please help on this?
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Postby Guest » Fri Nov 11, 2005 10:00 am

Sir Leo,

Made a mistake in the computation per above but also corrected in above thread (should be I = P/V). Anyways, you need not be paranoid. Above formula is applicable to linear (applicable to most audio power supplies) or switched mode power supplies. Pls note that the power factor is typical but efficiency a bit high - use 40% if not sure instead of 50%.

For your case, I assume that the 20amp peak current is inrush current. During initial plug in, the bulk e-cap is shorted (this is what the AC inlet sees) and current rises but slowly decreases as the bulk e-cap gets charged. Inrush current lasts for a few milliseconds. The fuse should be capable of handling this. You can check its I^2 x t (Inrush energy) rating. If its any comfort to you, at work we use a DC source with 4A max current rating to power up 800W power supplies. If you want, to minimize inrush current, put volume at lowest possible then turn on amp. After a few seconds, turn on cd then slowly increase volume in the amp. This is what we call slow start-up at work.

The ordinary UPS does not actually produce a clean AC signal (they look more like a triangular wave with flat tops) but since you have a linear power supply this should not be a big deal. However, APC is a good company so I assume they make good products. For switched mode power supplies, it is as there are more input harmonics.

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Postby rascal101 » Fri Nov 11, 2005 10:18 am

Sirs,

I log-in as Rascal101 but get cut-off after a few minutes. Maybe because at work we use a proxy server. I don't know??? Sorry, but I always turn up as guest when I send my reply.

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Postby rascal101 » Sat Nov 12, 2005 12:01 pm

Dear Sirs/Madams,

Just to be clear,

A. If you have an integrated amplifier or pre-amplifier with two channels

Given
--------
(1) output power1 = 10W per channel
(2) input voltage = 220V

for two channels,

(3) output power = 10 x 2 = 20W

Assumptions
----------------
(4) efficiency = 40%
(5) power factor = 0.5

Equations
-------------
(6) efficiency = output power/(power factor x input power)
(7) input power = output power/(power factor x efficiency)
( 8 ) input power = input voltage x input current
(9) input current = input power/input voltage
(10) input current = (7)/(2)
= 20/(.5x.4)/220
= 0.454A or 454mA

B. If you have a power amplifier with a single channel
item (3) is, output power = output power1

C. If you have a power amplifier with a two channels
same as A

D. If you have an integrated amplifier with multiple channels
item (3) is, output power = output power1 x n (no of channels)

E. So, if you have a pre-amp (10Wpc) and monoblocks (10W ea)

Current reqpt (pre-amp)
= 20/(0.4 x 0.5)/220 = 0.454A

Current reqt (monoblock)
= 10/(0.4 x 0.5)/220 = 0.227A

Tot Current reqpt = pre-amp + 2 x monoblock
= 0.454 + 2 x 0.227
= 0.909A or 909mA

Hope this clears things.

Thanks.

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Postby leo » Mon Nov 14, 2005 1:01 pm

rascal101 wrote:Dear Sirs/Madams,

Just to be clear,

A. If you have an integrated amplifier or pre-amplifier with two channels

Given
--------
(1) output power1 = 10W per channel
(2) input voltage = 220V

for two channels,

(3) output power = 10 x 2 = 20W

Assumptions
----------------
(4) efficiency = 40%
(5) power factor = 0.5

Equations
-------------
(6) efficiency = output power/(power factor x input power)
(7) input power = output power/(power factor x efficiency)
( 8 ) input power = input voltage x input current
(9) input current = input power/input voltage
(10) input current = (7)/(2)
= 20/(.5x.4)/220
= 0.454A or 454mA

B. If you have a power amplifier with a single channel
item (3) is, output power = output power1

C. If you have a power amplifier with a two channels
same as A

D. If you have an integrated amplifier with multiple channels
item (3) is, output power = output power1 x n (no of channels)

E. So, if you have a pre-amp (10Wpc) and monoblocks (10W ea)

Current reqpt (pre-amp)
= 20/(0.4 x 0.5)/220 = 0.454A

Current reqt (monoblock)
= 10/(0.4 x 0.5)/220 = 0.227A

Tot Current reqpt = pre-amp + 2 x monoblock
= 0.454 + 2 x 0.227
= 0.909A or 909mA

Hope this clears things.

Thanks.

Rascal101



Thanks for all the info.

What brand/model of UPS are you using? What would recommend if we decide to buy one and where can we purchase locally?

Thanks,
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Postby rascal101 » Tue Nov 15, 2005 12:59 pm

Sir Leo,

We use Liebert as our UPS. How to contact them? What number? I don't know. Liebert is a sister company and we order through our purchasing dept. I know patronizing your sister company is biased but that's what we use and we've had no complaints.

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Postby sillyputty » Mon Dec 12, 2005 2:23 pm

san po makakabili ng ups? and magkano po ang estimated cost? para po sa avr na 50wattsx7channels.
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Postby tony » Wed Dec 14, 2005 4:16 pm

tonydog wrote:I have a very good conditioner and AVR from Master Rivo. I saw how it worked yesterday during a massive lightning storm. The breaker shutdown and doesn't turn on untill you press the reset button. W/out that feature i think some fuses would have been fried or maybe worse.

How does the UPS protect in this situation?



magnetic contactor is the term for it! once it trips, you have to push the reset button for power to come back. sometimes a time delay relay van be used to reset the cricuit during a powe outage. this is very easy to do!
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