Recommend Dual Conversion UPS for Audio & Home Theater - Page 2 - AVS Forum
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post #31 of 44 Old 01-07-2007, 08:15 AM
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Originally Posted by Steve Bruzonsky View Post

Ya gotta do a little bit of homework instead of assuming that all "audiophile" claims are crap. HAAAA!

When are you leavin' for CES???

You're right, I speed read, and have been known to open my mouth when I have no idea what I'm talking about...

However, I'm VERY skeptical when PAD and others post things like his last post when he's apparently not involved in the technology. That to me then puts a Runco/Bose spin on things, and we all know how I feel about 'magic' in the a/v world.

I leave tomorrow afternoon, arrive at 10 PM. Leave again on Thursday AM. I left booking flights and accommodation way too late, they've reserved a cardboard box by the dumpster for me.

I'll be at the avs party and doing a whirlwind tour for the 2 days. No time for gambling, girls or goofing around..

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post #32 of 44 Old 01-07-2007, 08:26 AM
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Ok, after 7 minutes of intense (google) research (!) I see what they are talking about. That part is way over my little techy head.

There's no doubt of course that continuing research is bringing us better ways to accomplish stuff. Just 'cause I'm stuck in the 90s with CRTs doesn't mean I don't appreciate new things..

However, wild claims still need to be proven to me. I remember back in the 80s/90s when MOSFETs came out. They were touted to be more efficient than bipolar transistors, and most importantly, when the MOSFETs blow, they were supposed to blow OPEN instead of shorting out. As a tech, that interested me, and I installed a number of Ashly amps. While I still consider the Ashly product to be great stuff, I've repaired a number of them with shorted outputs.

Of course MOSFETS short out as much as bipolar transistors, and all claims of 'blowing open' have been 'blown out of the water'

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post #33 of 44 Old 01-07-2007, 08:43 AM
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Quote:
Originally Posted by Steve Bruzonsky View Post

Q: Can an ordinary, off the shelf, computer UPS product do the same thing as an AC regenerator?

A: No. Computer grade UPS systems are designed to support the specific requirements of computer power supplies and while they do an excellent job of protecting from surges and provide continuous power during blackouts (power failures) they have either no or very insensitive voltage regulation, do not remove harmonic distortion, allow some noise and transient voltages through and provide less than ideal sine wave AC output.

This statements just are not true for the mid-range and hig-end products.

Yes, they are true if you are comparing a real power conditioner to a $150 shoebox line-interactive UPS, but that's not what we're talking about. In fact, I know that several of us have made this distinction repeatedly.

Quote:


Regarding the Audiophile UPS 1050 discussed above, here's what they say about PC UPS compared to their unit:

http://www.audiophileaps.com/FAQs.htm

"Computer UPS systems such as the APC SmartUPS do not perform full continuous power conditioning, but pass through the AC power from the wall outlet, turning on their battery powered AC inverters only in low voltage (usually <95 volts) or blackout conditions. Their battery life tends to be limited. They also tend to be noisy and intrusive unless housed in a separate room or electrical closet."

Ya know, this statement is rather like comparing the performance of a Ferrari to a Chevette. The APC SmartUPS is a low-cost, line-interactive UPS, which was never designed to do any power conditioning.

However, there is one way in which it is identical to the 'regenerator' you are obviously trying to sell us on. The 'regenerator' also goes into bypass mode when it is unable to supply enough power. Now, when the unit is in bypass mode, how much protection do you think it's giving your equipment? If the difference of adding the conditioner is enough to hear, don't you think it would be quite audible when it bypasses and connects directly to the line? How is this a 'feature'?
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post #34 of 44 Old 01-07-2007, 09:07 AM
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Quote:
Originally Posted by MauneyM View Post

Yes, and you can also very closely approximate a sine wave using a summation of discrete square waves. With minimal output filtering, you can EXACTLY reproduce that sine wave with a series of square waves.

If you don't believe this can be done, then you clearly do not believe that a sampled digital music file can reproduce anything resembling a clear musical pitch from a bell, a flute, or a violin. Nyquist, anyone?

Think about it for more than a couple of seconds, and the ludicrousness (is that a word?) of the original statement becomes obvious.


This is not the way it works. A Square wave can be considered to consist of a large number of sinusoids of different high frequencies according to Fourier transforms. The converse does not apply. You are confusing this situation with the area of sampling rate for audio/video purposes.

In the situation where you are trying to reconstruct the original signal (analog) from discreet digital or stepped square waves (from the DAC), you need to apply some sort of low pass filtering to remove the high frequency components (sinusoids) from the signal and then use that signal to drive your amplifier or speakers. The rising/falling edges of the square waves are of extremely high frequency and must be smoothed by the filters prior to use by the amplifier stages and your speakers.

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post #35 of 44 Old 01-07-2007, 09:07 AM
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[quote=Curt Palme]

However, I'm VERY skeptical when PAD and others post things like his last post when he's apparently not involved in the technology. That to me then puts a Runco/Bose spin on things, and we all know how I feel about 'magic' in the a/v world.
QUOTE]
For business reasons it would be entirely inappropriate to comment on any involvement with this or other technologies. Not being involved with that company doesn't mean I am not involved with technology. I was just trying to help you be less skeptical that technology does work and that nano-whatever is real. So now that you have read up on it, it appears you see some logic in what they are saying. That's cool. Have a good one.

And please don't mention my name in the same sentence as Blose!
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post #36 of 44 Old 01-07-2007, 11:21 AM
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Quote:
Originally Posted by Steve Bruzonsky View Post

Q: Can an ordinary, off the shelf, computer UPS product do the same thing as an AC regenerator?

A: No. Computer grade UPS systems are designed to support the specific requirements of computer power supplies and while they do an excellent job of protecting from surges and provide continuous power during blackouts (power failures) they have either no or very insensitive voltage regulation, do not remove harmonic distortion, allow some noise and transient voltages through and provide less than ideal sine wave AC output.

Whoa, whoa, whoa, way too broad a statement. That's like saying your Bryston amps are no better than a boxed 5.1 system amp. An amplifier is just an amplifier right? There is a wide range of quality in UPS systems just as there is with any hardware.

Let me break UPS system down to four basic classes:

1) The cheapest is an "offline UPS" which is nothing more than a battery powered simple inverter connected through a DPDT relay to the outlet. The relay coil is connected to the incomming AC line. When the AC line drops, the inverter starts up, the relay relaxes and the inverter is switched to the outlet on the back. This all takes time - many hundreds of milliseconds. SMPS power supplies can ride this out of they are not heavily loaded and that's why these systems work well in certain applications. The output of this class is almost always a nasty square wave full of noise. Also things like ethernet switches and monitors can handle a glitch. But there is no regulation and in fact when not on the battery, they are just simply passing the AC cord right trhough to the outlet. They may throw in a Pi filter and MOV, but a cheap power strip can do that too. Easy to find at Best Buy and Wall Mart.

2) "Interactive UPS" These use solid state switching that can react within an AC cycle. Though not totally glitch proof, they are much better than the above. Also with these the inverter can come on line and assist the incomming AC line voltage. They can increase it if it is low but typically do nothing if it's too high. This is a form of regulation. As the inverter must now be synchronous with the AC line, it's design is far more complex. Also the output is more often than not a modified square wave or "stepped" square wave to better approximate a sine wave. Better computer and electronic stores carry these.

3) "On-Line UPS" In this class there is no relay or switch for changeover. That's because the inverter is always powering the load outlet. The incomming AC is converted to DC and the battery pack is summed to it with diodes. That means the two DC sources are combined to feed the inverter. (It's actually a bit more complex in that the line obtained DC is a bit higher to keep the batteries baised off until needed, but there is no significant switch time.) While these system can get by with a square wave or stepped sinewave, they are almost always true sine wave as the quality class demands it. As the inverter is the power source, it is re-generated AC and we don't need surge protectors or filters in it's output. As the AC power is re-generated, it is easy to tightly regulate. These are typically not found on store shelves and must be ordered from specialty suppliers.

4) "Facility Wide UPS" These are the same as #3 except built on a massive scale to protect an entire technical facility such as bank and insurance headquaters. Also at home in TV broadcast centers and medical facilities where power loss is simply not an option. They typically take in 3 phase 480v and output the same. Then distribution transformers drop this down to 120/208v and distribute to breaker panels and dedicated outlets. This is because in large buildings, 480v can use thinner wire with less voltgae drop over long runs. You place the transformers in local electrical closets. These systems are also often paired with backup generators. That's why most of the se large systems only have 15-20 minutes of reserve. That's plenty of time for the generator to start and stabalize. These systems are very low in THD and have internal redundancy on many levels. They regulate within 1% which is way beyond any connected device requirements. They also have to be servicable hot and have synchronous bypass switches so they can be shut down and brought up without a glitch to the load. These systems are custom build and can cost upwards of a millions.

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post #37 of 44 Old 01-07-2007, 11:26 AM
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This is not the way it works. A Square wave can be considered to consist of a large number of sinusoids of different high frequencies according to Fourier transforms. The converse does not apply. This is not the way it works. A Square wave can be considered to consist of a large number of sinusoids of different high frequencies according to Fourier transforms. The converse does not apply.

AV Doogie, the converse is indeed valid. There's no confusion here. But to be clear, it is really more of mathematical interest than it is of practical interest.

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post #38 of 44 Old 01-07-2007, 11:46 AM
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I am looking at the practical use. But as far as mathematics are concerned, this does indeed work....my bad. You need an exremely high sampling rate to make the output look like a sinusoid without filtering. Akin to using calculus with integration limits to infinity

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post #39 of 44 Old 01-07-2007, 07:06 PM
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Quote:
Originally Posted by AV Doogie View Post

You need an exremely high sampling rate to make the output look like a sinusoid without filtering. Akin to using calculus with integration limits to infinity

You don't need it to be as high as you might think. You have to take into account the load (and source) impedance AT THE FREQUENCY OF INTEREST. In this case, it's the frequency of the harmonic, not the fundamental. Now, our normal power systems (and power supplies) are designed to have minimum impedance at 60 Hz (the reason for this should be obvious).

Practically speaking: If you use a 16-point curve, the Nyquist is 480 Hz. 128 points gets you to 3840 Hz. This is pretty easy for an output stage to generate, and is high enough that it won't get very far in a normal 60 Hz distribution system. Under any circumstances, it's not very difficult to add enough inductance to get rid of a 4kHz signal on a power line without reducing your power output significantly.

[FWIW, keep in mind that a CD only uses 2 points to represent a 20 kHz signal. When it reaches the analog output, it's a perfect sine wave.]

Make sense?
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post #40 of 44 Old 01-07-2007, 09:16 PM
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Ya know, if Mauney and Doogie got together, they'd design something SPECTAULAR!

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post #41 of 44 Old 01-08-2007, 06:33 AM
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Quote:
Originally Posted by MauneyM View Post

[FWIW, keep in mind that a CD only uses 2 points to represent a 20 kHz signal. When it reaches the analog output, it's a perfect sine wave.]

Make sense?


Yes, with brickwall filtering.

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post #42 of 44 Old 01-08-2007, 06:34 AM
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Originally Posted by Curt Palme View Post

Ya know, if Mauney and Doogie got together, they'd design something SPECTAULAR!


Mom, they're picking on us geeks again

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post #43 of 44 Old 01-08-2007, 05:33 PM
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Mom, they're picking on us geeks again

That's OK - we'll just fix their PS3s so the cheat codes don't work.
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post #44 of 44 Old 01-10-2007, 02:23 PM - Thread Starter
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I was at Fry's Electronics the other day. Over next to the PC section, they had a stack of APC "Home Theater" UPS units selling at $499. I didn't review the specs or look at them carefully.

"Doug Winsor" used to troll at some AV Forums as "Steve Bruzonsky"! My home theater at:
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