Several members in other threads here have alluded that dual conversion UPS
units would be cost effective for audio and home theater, but the market is too small for those companies to advertise for home theater.

Market too small. Tell that to HDTV manufacters? If these units are available at a price range of $1,000 to $2,000, perhaps even $2,500, I suspect there's a good market for them.

But no one has given specific models, prices, and web links to features. And I really haven't ever seen anyone post this info on the web? Are such models really available and at what cost?

And hey, if they are, I'm interested in learning more and demoing.

Thanks. :D

Almost all dual-conversion UPS units currently available are digital ie. they use what you have referred to as class D amplifiers in their output. That is a major factor against acceptance by the traditional audiophile, but that is how they achieve their 90% plus efficiency. The older analog versions invariably used output transformers which may or may not be a good thing, depending on your point of view.

Almost all dual-conversion UPS units currently available are digital ie. they use what you have referred to as class D amplifiers in their output. That is a major factor against acceptance by the traditional audiophile, but that is how they achieve their 90% plus efficiency. The older analog versions invariably used output transformers which may or may not be a good thing, depending on your point of view.

I know that Class D amps generally are not as good sounding as Class AB amps, as I've demod some. But to what extent Class D vs. Class AB would make a sonic difference re AC regeneration I haven't demod and don't really know. What are you throughts on this?

Hi

The amount of distortion introduced by a decent digital inverter in a 60 Hz is negilgible and is order of magnitude smaller than what comes out of ANY audiophile Line Conditionner.

The PS Audio is one of the few products coming from an Audiophile manufacturer that actively generate their OWN AC.. DUal COnversion is just that. First use the AC and make it DC. it charges a bunch of batteries which can be seen i this context as huge capacitors and they filter most of the AC ripple. THis new Power now DC is presented to an oscillator/amplifer whose sole purpose is to produce /amplify ONE waveform.. the problem associated with Digital amplifers namely production of higher harmonics acan be mitigated by an output transformer or an inductor( choke) , or which is currently used by products from APC and Liebert for example.
I am not too sure the traditionnal UPS companies have addressed the tiny audiophile market. APC does have some HT products I do not know and would not think they are Dual conversion.

The really amusing part however for me is the reluctance of the audiophile community to try something that does not have some kind of "audiophile" twist to it... Namely that the transformer would be from "long" crystal, cryogenically treated copper or Silver wire... The heavy duty Dual conversion UPS will power ANY sane HT with ease. A 10 KW model is less than $7,000. Installation could be an issue, it ican be involved since you are actually installing a new source of electrical power in the house. With more people installing back-up generators in their house, maybe this could be less of a problem.
I am repeating myself here. NO Audiophile Power conditionner from any of the usual suspects can be as effective as a real dual conversion system

But no one has given specific models, prices, and web links to features. And I really haven't ever seen anyone post this info on the web? Are such models really available and at what cost?

Yes, I did - it was the Powerware 9155. The link was to a 15kVA model, which would be massive overkill for any sort of audio system or home theater.

The reason that you won't see much of this type of information on the web is due to the target markets for these devices. A data center manager doesn't purchase 750kVA of UPS capacity and a several roomfuls of batteries by searching the web for a 'deal' - it's all quoted and done through reps, consulting/specifying engineers, and/or manufacturers service organizations. The reps for a given area are listed on each of the major manufacturers' webstes - the ones I listed several threads ago.

Also, pricing is not as simple as you might think at the high end of UPS systems because there are several steps in the selection process. 1) You analyze and select your load capacity. 2) You determine the amount of headroom (or future capacity) desired. 3) You decide whether you want a single exact-sized system, parallel redundancy, parallel capacity, Parallel N+1 capacity, Parallel N+1 redundancy.......etc. 4) You decide your minimum load-loss run time. 5) Finally, you select your battery sizes and types. (Weight is actually a big part of this - what can your data center floor hold?).

Now, understand that the guys who do this for a living (selling multi-million dollar systems) aren't really focused on the small handful of audiophiles who can hear the difference made by a double-conversion system with very high-performance amps. Could they sell a product to them? Sure, and I'd bet they would be happy to quote it and help you select a system. But I'd have a hard time seeing them spend the money to really go after this market - it's just too niche and limited, and there is little or no follow-on market for service.

I know that Class D amps generally are not as good sounding as Class AB amps, as I've demod some. But to what extent Class D vs. Class AB would make a sonic difference re AC regeneration I haven't demod and don't really know. What are you throughts on this?

This is irrelevant, since the 'amp' is not in the signal chain. The only issue for a power conditioner is the quality and stability of the output power. A clean, well-regulated 60 Hz sine wave capable of delivering enough current to drive your devices under all the expected conditions without inducing voltage sags, ripple, or flicker is the goal; how you arrive at the goal makes no difference once it has been achieved.

Transformer output designs actually cause problems for devices with significant load variations; the output impedance is high enough to cause a voltage sag that the source (control circuit) doesn't directly see. You can also end up with inductive effects that you don't want - better to stay with direct-drive if the control system is fast enough to generate a clean output wave.

NO Audiophile Power conditionner from any of the usual suspects can be as effective as a real dual conversion system

I'm not sure I'll go that far (there may be something I haven't looked at), but I'll certainly say that I haven't seen one that has specs anywhere close to the current UPS IGBT technologies.

Thanks guys. Sounds like dual conversion UPS is a wonderful way to go but that you've gotta spend some good bucks to go there.

I did a web search and found pricing for the Poweware 9155. Starts at over $7,000.

http://www.powerware.com/UPS/9155_pricing.asp

With some of the megabuck home theater installations you'd think there's be at least a few folks that actually use these for home theater and/or audio???

Try looking at the source side of things......
Powerware's Digital TV focus (http://www.powerware.com/Digital_TV/Solutions.asp)

You'll notice that they have plenty of connections with and understanding of DTV markets. Frankly, our little hobby is small potatos in comparison with the needs of broadcasters and content producers - even at the high end.

I did a web search and found pricing for the Poweware 9155. Starts at over $7,000.

OK, try the 9120. It starts at $649 for a 700VA unit, $1,099 for a 1500VA unit (These prices are from the manufacturer's website). Complete isolation through a double-conversion online UPS.

Powerware 9120 UPS (http://www.powerware.com/UPS/9120_pricing.asp)

OK, try the 9120. It starts at $649 for a 700VA unit, $1,099 for a 1500VA unit (These prices are from the manufacturer's website). Complete isolation through a double-conversion online UPS.

Powerware 9120 UPS (http://www.powerware.com/UPS/9120_pricing.asp)

CompUSA online has it for $797.99, the 1500VA unit.

http://www.compusabusiness.com/products/product_info.asp?pfp=SEARCH&Ntt=powerware+9120+ups&N=0&Dx=mode+matchall&Nty=1&D=powerware+9120+ups&Ntk=All&product_code=52486259&Pn=PW9120_1500VA_UPS_120V_PERP

Here's the specs, including less than 3% THD.

http://www.powerware.com/UPS/9120_Specs.asp

That $7000 plus Powerware UPS noted above had THD of less than 5%.


Questions:

1. How important is the THD % for high resolution audio in particular?

2. Are any of the outlets isolated from each other, as isn't this important especially to isolate analog from digital components? My impression from the below pamphlet is that they aren't, but maybe I'm wrong.

http://www.powerware.com/UPS/9120_info.asp

I looked up the initial Secrets of Home Theater review on the PS Audio P300 from 1999, when it first came out, because it was done by Stacey Spears, a Microsoft engineer who knows his stuff. He is one of the very few technical reviewers as opposed to audiophile reviewers. I was interested if he had anything to say about UPS units.

Here's the review:

http://www.hometheaterhifi.com/volume_6_4/ps-audio-power-plant-300.html


Here's what he said about UPS units:

"DC Galvanic Isolation

What?!? That is the technical term for what a UPS (Uninterruptible Power Source) and the Power Plant do. It simply means turning AC into DC then back into AC. It is the ultimate approach for cleaning up those nasty noise makers that might be on the AC.

Are all AC-DC-AC converters created equal? No way! A lot of UPS devices intended for PCs do a poor job at this. They essentially lay many square waves on top of each other, even though, according to Fourier’s theory, if you lay enough sine waves on top of each other, you create a square wave rather than the other way around. Also, many computer UPSs inject high frequency distortion into the new AC, and this comes from the device used to generate the sine wave itself.

Does that mean that all UPS are bad? Again, of course not. Some industrial UPS devices costing lots of $$$ do an excellent job. A nice Toshiba UPS will run you about $3,495. That is just one model that I investigated before I had even heard of the Power Plant."

"F igure 2 is the output of a typical computer UPS when running on battery power. Pretty ugly huh? "

1. How important is the THD % for high resolution audio in particular?

95% is pretty darned good for an inverter-generated signal, and better than many utility feeds. Coupled with the tight voltage regulation, there should be no problems.

2. Are any of the outlets isolated from each other, as isn't this important especially to isolate analog from digital components? My impression from the below pamphlet is that they aren't, but maybe I'm wrong.

Look below at the 'Load Segments' link. There are multiple groups with programmable load-shedding and power sequencing.

Info (http://www.powerware.com/UPS/9120_features.asp)

Here's what he said about UPS units:

[...]

Does that mean that all UPS are bad? Again, of course not. Some industrial UPS devices costing lots of $$$ do an excellent job. A nice Toshiba UPS will run you about $3,495. That is just one model that I investigated before I had even heard of the Power Plant."

"F igure 2 is the output of a typical computer UPS when running on battery power. Pretty ugly huh? "

Typical? BS - this is just not true in today's UPS market, and it wasn't even correct in 1999. This may be true for the $100 shoebox unit you can buy at Staples to sit under your desk, but any current online double-conversion model designed for serious applications by the reputable vendors will be as good as the 'audio designs'.

Are all AC-DC-AC converters created equal? No way! A lot of UPS devices intended for PCs do a poor job at this. They essentially lay many square waves on top of each other, even though, according to Fourier’s theory, if you lay enough sine waves on top of each other, you create a square wave rather than the other way around. Also, many computer UPSs inject high frequency distortion into the new AC, and this comes from the device used to generate the sine wave itself.



You can approximate a square wave using Fourier transforms. Which is a mathematical use of many higher frequency sinusoids to approximate a sqare wave. Using this same analogy, a square wave can be considered to consist of an almost infinite number of sinusoids of varying frequency....which is akin to having many harmonics or multiples of the original frequency. Many UPS units which provide power using a stepped or modified sine wave produce a horrible amount of harmonic content,thsu polluting the very power you want to be clean. A high quality low pass filter will clean up the higher frequency harmonics and provide you with a much nicer sinusoid. Power filters are not cheap, and do require electrical components with high tolerance and therefore higher cost.

You can approximate a square wave using Fourier transforms. Which is a mathematical use of many higher frequency sinusoids to approximate a sqare wave.

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.

They essentially lay many square waves on top of each other, even though, according to Fourier’s theory, if you lay enough sine waves on top of each other, you create a square wave rather than the other way around.

Gimme a break. This guy may be respected in some field, but digital signal processing obviously ain't it. If he does understand it, then he is intentionally making a statement designed to mislead the reader.

By the way, even with my outstanding electrical/grounding system, the meter on the front of my new Premier Power Plant shows incoming AC with 3.3% THD, and outgoing (to components) of about .3% average THD.

Lot less THD than discussed above on the dual conversion UPS units. That's why I asked you folks how important is THD on the AC for both audio and video?

Gimme a break. This guy may be respected in some field, but digital signal processing obviously ain't it. If he does understand it, then he is intentionally making a statement designed to mislead the reader.

Have you noticed that you are G-D any anyone else, including engineers with technical backgrounds as good or even more than your own, no nothing if they don't agree with you?

Stacy Spears is well respected in both the computer and audio engineering circles. Are you? And AV Doogle is an engineer in the power business as well as he has a respectable home theater. I am certainly interested in learning from technical folks - but I do have to sort out their disagreements and determine what I think. And its nice when they can respectfully disagree rather than get nasty and accusatory.

Stacy Spears is well respected in both the computer and audio engineering circles.

Perhaps, but the statement that you quoted was laughable on its face. I think I pointed out the fallacy quite well, and I don't believe it takes a PhD to understand why the original statement was at best misleading.

BTW, I do have my own credentials in both power systems and digital signal processing - including high-end products and patents. I generally prefer not to elaborate in public forums like this - my employer takes issue with it.

Also, I don't think I've had any significant disagreements with AVDoogie since this thread started. Frankly, I think his posts have been pretty solid, and they seem to agree quite well with what I have observed. [Edit: I went back and checked, and I don't believe AVDoogie and I have been in disagreement at all on any point yet in this discussion. In fact, I've found at least one point where I quoted him as being absolutely correct.]

I agree that Stacey is well respected in his field. He's earned it.

But it is also true and that he stepped way out of his league with that statement. Mauney's right, it's embarrasingly wrong.And its nice when they can respectfully disagree rather than get nasty and accusatory.Oh Steve, give it a rest. Your "confrontation threads" are just the same pettiness done another way. It's not as clever as you seem to think it is.

any thoughts of running balanced isolation transformers after these dual conversion units? Do these dual conversion units function properly if fed balanced AC?

By the way, even with my outstanding electrical/grounding system, the meter on the front of my new Premier Power Plant shows incoming AC with 3.3% THD, and outgoing (to components) of about .3% average THD.

Lot less THD than discussed above on the dual conversion UPS units. That's why I asked you folks how important is THD on the AC for both audio and video?

A couple of points.

1) correct me if I'm wrong, but THD measurements are made of differences between an input and output. THe difference in the waveform of in vs out is THD.
Can you measure THD of an incoming signal only? (and I could well be wrong, THD theory etc isn't my strong point.)

2) THe THD even if you can measure it of an AC power supply (AC outlet) should be immaterial since everything gets converted to DC within the amp regardless whether it's a linear power supply or an SMPS. I'd think the noise generating distortion (if you think it can cause problems in amps) would be pulses and crap riding on top of the AC sine wave, and that's not THD, is it?

Curt, THD is measured on the AC, that's why the UPS units mentioned above list THD in their specs. As my AC line, from the wall, has about 3.3% THD, if I connect straight from the wall, that's what I get. But assuming that the Premier Power Plant's readings are correct, using the Premier to power my front end components has .3% THD on the AC line from the Premier to the components. The UPS units discussed above are speced for 5% and 3% THD.

I would still like someone of engineering acumen to explain how THD on the AC affects both analog and digital switching power supplies. Thanks.

Sure you can measure it on the input only, because you have a reference for what the signal ought to be: a pure sine wave. If the power coming in has any components at other frequencies you can detect that.

Curt, THD is measured on the AC, that's why the UPS units mentioned above list THD in their specs.

Correct. THD, by definition, is the amount of energy in the signal that is composed of non-fundamental harmonics of the base frequency - 60Hz in the case of US AC power. There are actually two different definitions - THD, and thd; they differ in that THD is a %age of the total energy, while thd is a percentage of the fundamental energy.

I would still like someone of engineering acumen to explain how THD on the AC affects both analog and digital switching power supplies. Thanks.

In small amounts (<5%) it should have no discernible effect on the output of ANY solid power supply design, SMPS or linear.

At increasing levels, you can expect linear supplies to begin to have heating and noise issues, as the energy in the harmonics can cause excessive losses in the transformer. These inductive losses actually block the noise from getting into the DC side of the supply; the requisite capacitive filtering and voltage regulation stages will further isolate this noise from the output DC rails. Bluntly, if the capacitors can't filter out 5% THD, then they can't filter out the 60 Hz base wave that comes out of the rectifier. You might potentially have some inductive coupling (EMC) that would allow mid-frequency noise to get into the high-impedance circuitry elsewhere in the product, but this would be a product of very poor design in shielding and layout - not a problem with the PS. Now, you CAN have certain frequencies that will pass through a linear PS, and there is a point where the caps just can't filter out everything, but it tends to take quite a bit of 'junk' on the line to cause real noise to appear on the DC side. Transients are a much bigger issue with linears; they often dump a noise event into the device ('pop'); however, it doesn't take a $3500 power conditioner to deal with transients.

[Caveat: if the PS design has some bizarre resonant point that happens to line up with a non-fundamental frequency represented in the line voltage, it could cause overheating and reduce the supply's ability to deliver it's design-requirement current. In this case, the only good solution may be to use either a tuned filter or a double-conversion system.]

SMPS are a different animal entirely. SMPS devices actually like a square wave, as they can convert all of the energy in the harmonics, as well as in the fundamental. They actually create a tremendous amount of distortion in the switching process, then filter it all back out on the output side. THD should have NO impact on a SMPS. This is why the el cheapo 'shoebox' UPS units at the big-box office stores can get away with putting out a square wave (or 'modified' square wave) - all PCs and most other office devices use SMPSs, and are perfectly happy with that kind of power.

This is why you get so many people questioning the value of power conditioning for projectors that use a SMPS; there's just no good reason for it to matter. If it does make a difference, it is probably due to grounding, shielding, or some other system problem - not a line noise or voltage regulation issue.

Guys, I work for the company who owns Powerware. I know the chief engineering guys there but I am NOT an EE nor an EXPERT! Anyways, I emailed them the link to the Audiophile APS 1050 unit I was considering (and did purchase) and their response was that nothing they offered was as tightly spec'd as the unit I was after. And the 1050 did address all of the PQ issues. Not that I could hear any difference and spurred on by my ignorance of these things, I bought the 1050 unit. Sure I can get a decent employee price on all Powerware stuff, but when they said the 1050 was as good as they read, I went with it.

BTW, dirty power to data centers, banks, etc. is why Powerware is about a $billion business today. With more sophisticated electronic equipment susceptible to the fluctuations and variations in electrical power, the need to protect said sophisticated electronics is ever increasing. Hence the argument that our own sophisticated electronics in our home systems need protecting. It is real and it costs businesses billions of dollars a year in damaged equipment and lost business. (end of sales pitch - no I am not in sales.)

PAD---I certainly don't dispute your claims but the term "dirty power" you're using encompasses far more than the THD issues being discussed here. I don't think that anyone here is disputing the notion that surges, over/under-voltages, spikes, etc. can cause damage to electronic equipment; indeed, many of us have lost at least once piece or another. What we're talking about here is more about cleaning up a stable power source with a dirty sine wave than it is about protecting equipment from occasional events. (Though again, that's not to say the latter isn't important.)

Hey Steve, the 1050 unit regenerates power as well. When I saw that it did that AND protected against the power quality gremlins I was very interested. Not being smart enough to know I may not have needed such an expensive beast I quickly moved past the Powerware units for my system. I'll sit back and see how this goes and maybe save myself some money by selling off my 1050 for some Powerware stuff.

BTW, Mr. Mauney is the expert here on this subject. I know him personally and for now I am toying with him as he hasn't figured out who I am yet. He does have a distinguished background in this field and hands-on experience creating and spec'ing these systems.

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.


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."

After now reading some stuff on the Audiophile unit, I can see what PS Audio came out with the Premier Power Plant. PS Audio started the audiophile power regeneration back in 1997. Then Exactpower came along. More recently Audiophile came along.

Audiophile legitimately compared their product to the others noting why they felt theirs was better, including that they have battery backup:

http://www.audiophileaps.com/pdf/Comparisons.pdf

Now PS Audio has evened out the competition with the Premier Power Plant. The differences between the Premier Power Plant and the Audiophile unit, that I can see,
involve primarily that the Audiophile unit has some batter backup, but the Premier Power Plant uses nanocrystals for isolation and 1/4 inch copper bars for AC signal path. And the
Premier Power Plant also has a Multiwave option (initially, the MW clearly sounded better to me and a good friend than 60 Hz sine wave. But now a bit more than a week later, with burn-in, I seem to be finding that good ol 60 Hz sounds better than ever, and although Mulltiwave sounds real nice, it has a bit too high of a pitch in comparison to 60 Hz).
At least these differences are important to me.

Steve, I tuned out when 'nanocrystals' came into the equation.

Steve, I tuned out when 'nanocrystals' came into the equation.

Curt, earlier in one these threads at this forum someone posted web links re the nanocrystals and that this is legitimate technology being used in AC power stuff.
Ya gotta do a little bit of homework instead of assuming that all "audiophile" claims are crap. HAAAA!

When are you leavin' for CES???

[QUOTE=Steve Bruzonsky]Curt, earlier in one these threads at this forum someone posted web links re the nanocrystals and that this is legitimate technology being used in AC power stuff.
Ya gotta do a little bit of homework instead of assuming that all "audiophile" claims are crap. HAAAA!
QUOTE]

Nanotechnology can be applied to many, many technologies/products. I can say no more here but let's just say that while I have not looked at the above-referenced item, nanotechnology is coming on strong on many fronts. Wish I could say more, but I cannot publicly. Sorry to be obscure. And I in no way work for any audio component company, just for the record.

I'm backing out of this conversation now as power discussions are well past my pay grade.

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..:(

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' <groan>

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.

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'?

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.

[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! :rolleyes:

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.

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.

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

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?

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

[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.

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


Mom, they're picking on us geeks again :p

Mom, they're picking on us geeks again :p

That's OK - we'll just fix their PS3s so the cheat codes don't work. :D

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.