POWER GAMES:Servo Stabilizer,CVT or Online UPS?

[newlash09]

Below is a copy and paste from an excellent write up by our forum member hifiashok , almost a decade back



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• Audio Video Accessories

Constant Voltage Stabilizer - CVT - Explained

• Thread startermadbullram
• Start dateDec 9, 2009

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murali_n
Well-Known Member
Dec 9, 2009
#21
Hai Thad,

Not necessarily

N.Murali

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Thad E Ginathom
Well-Known Member
Dec 9, 2009
#22
Let me borrow that wall... I want to bang my head against it! :lol:

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abhifusion
New Member
Dec 10, 2009
#23
I bought 2KVA servo stabilizer from Lotus Autotron , Pune ...
I had given him idea that i'll be using it in house for LCD,Fridge n Comp ...

But when we called electrician for setting it up , he said its 1Phase and for house you need 3 Phase stabilizer :sad:

what do i need to do now ?? I paid 5k for it !!

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murali_n
Well-Known Member
Dec 10, 2009
#24
Hai,

Connect all the appliances in a single circuit and connect this circuit to the output of the servo.

One point I would like to mention is why do you connect the Fridge to a Servo stab ? Because the compressor will switch ON & OFF many times per hour and every time that load will cause volt drop , which is going to make the servo motor to adjust the Voltage and ultimately the maintanence work in your stab will increase.

Servo stab are meant to be used for precise control of voltage for sensitive equipments like computer and communication equipments.

Just my 2 cents.

N.Murali.

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cmsajith
Well-Known Member
Dec 10, 2009
#25
Thad E Ginathom said:
Does that mean that the voltage of an ordinary household stabilizer will be jumping?

My hifi (and my wife's laptop) is connected to a small (APC Back-UPS500) UPS, which I was hoping would regulate the voltage as well as provide backup for short outages. However, the amplifier usually trips off on a power cut. It is more sensitive than a computer! Other components remain on.

Whilst I don't want to spend a lot of money on a stabiliser, I doubt that I'll be able to afford the same quality amplifier again, so protection is important.
Click to expand...
Normally all the "household voltage stabilizers" which are available in the market will do the voltage correction, but it will not do a smooth correction. Rather those stabilizers should be called voltage boosters. When the output voltage drops from its permissible range, it will give a boost of 30-40v (it will be mentioned in the manual) to keep it in the range and the reverse will happen at the maximum range. So as you told we can say there will be a jump in voltage and it will become worse if the fluctuation is very high and last for a long time, you will hear the continuous "tick" sound from the relays inside.

Whereas a servo stab will have a constant sensing circuit for the output voltage and built in stable reference voltage source. The solid state control circuit operates the motor whenever the output voltage falls or rises beyond the preset voltage (usually it will be + or - 2 or 3v). The motor is mechanically attached (contact using a brush) to the arm of a continuously variable auto transformer for the smooth voltage correction and the movement make the sound. Since the servo motor is correcting the voltage, the correction time will be slightly more compared to others, but it will be smooth and the correction will be within 2 or 3v. If the fluctuation is happening for a long time or it is frequent the motor arm will try to adjust constantly and thereby the wear and tear of the brush will be more and early.

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cmsajith
Well-Known Member
Dec 10, 2009
#26
I have posted the pictures of my servo stabilizer in the following post:
http://www.hifivision.com/audio-vid...mi-rf-filters-surge-suppressor.html#post94242

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hifiashok
Well-Known Member
Dec 10, 2009
#27
there are usu. three kinds of UPSs, off-line, on-line and line-interactive.

off-line UPSs usually are cheaper, lower efficiency solutions. they deliver electricity using the batteries only when there is none from the mains.

line-interactive UPSs are a compromise on cost and quality and are ok for computer use. the crux is the switch-over time (optimally needs to be 5-6ms or then the comp. may reboot, data losses may occur or damage to the electronics is possible).

on-line are the best (among UPSs), for computer and other sensitive equipment needs. this is coz. differential o/p is generated from the batteries, irrespective of the fact that electricity is on or cut, meaning there is waveform correction (square to sine).

so, no AVR needed in on-line. PWM (pulse width modulation) us used.

in on-line UPSs, AC is converted to DC (say input of 230V AC to 180V DC) then AC is regenerated from DC (say input of 180V DC to 220V AC). so, o/p AC is cleaner and constant.

UPSs (incl. on-line) however, are bad choices for audio (since they use a switching frequency of 14.4KHz to 16KHz that could introduce harmonic distortion and noise).

the off-line and line-interactive UPSs need AVRs but the quality of the AVR (or the total lack of it) is a price/market dependent variable.

AVR work using relays for step-up or step-down (physical moving devices).

Line-interactive UPSs usually go upto 1.5KV. Only APC goes upto 5KV.

APCs used to have a lot of issues in India since the designers in the US were not aware of electricity issues here. However, over time, they seem to have customised their offerings for Indian conditions.

coming to servo, correction time, owing to the physical movement of the motor/brush, is approx. 35V/sec where correction in the on-line UPSs is in millisecs. servo also does not do any waveform correction.

consequently, IMHO, for audio use, CVTs are the best option (when not incl. power re-generators in the list of options, like Power Plant from PSAudio). esp. when from companies like Bhurji, that are and have been at the epitome of power conditioning for many years.

CVTs handle harmonic distortion. They handle waveform correction. They work on the saturated core principle so are able to deliver best, clean and stable power. the manufacturer's credentials and R&D are critical to a good CVT design as 'balancing' is a key requirement, esp. since there are 04 coils. and, of course, use of the highest quality of materials.

A CVT, by virtue of its design, is 85% efficient (approx. 15% heat, etc., loss).

Secondly, owing to the large transformers therein, there is an avoidable hum.

Consequently, there are CVT usage best practices, viz.,

1. Try and install the CVT in a room/area other than where the audio eqpt. is, to avoid the irritating hum.
2. Try and keep the CVT atleast 3m away from the audio eqpt. to avoid harmonic distortions.
3. Try and keep the CVT in a well ventilated area to dissipate the heat generated.
4. Depending on the distance of the CVT from the equipment, quality and gauge of the power connecting wire/s need/s to be calculated carefully.

http://www.hifivision.com/audio-vid...ssues-power-supply-inverters-3.html#post32447

 

[haisaikat]

Digital sources, DACs and preamps are the sensitive electronics in the chain, that usually don't come with very robust power supplies. And they need all the pure power that can be supplied. And on the positive side, their current draw is not much. So the below are to be achieved in the same :
1. Keep voltage constant - CVT or servo stabilizer
2. Isolation from power line noise - isolation transformer.
3. Keep power properly shaped - pure sine wave regenerators or some models of online ups that achieve the same. Even some CVT achieve the same.
4. Galvanic isolation between all source components, especially kit having SMPS modules like Amazon fire TV sticks and cell chargers.

I have been considering a combination of CVT + isolation transformer to achieve point nos 1 to 3. I have a star wired power block that achieves the galvanic isolation required as per point no.4. So depending on the number of boxes you can accommodate, you can go for an all in one, or seperate boxes. Just like in a audio chain, seperate boxes offer better power than one integrated solution.

Bhurjitransformers Index

+91 (124) 4001172-75, 3012041-42

Are you using the CVT from Bhurji? Is there a CVT that will take care of 1,2,and 3? For 4, in my audio chain out of Little Dot MK II pre-amp looks to be having a transformer already, CS 851C CDP and Allo Digione, only the Digione is using a SMPS power, as such only that would be requiring a Galvanic Isolator right? I am also checking if powering the digione with power banks that claim to provide 3 amp / 2.4 amp in a single output port can be an option although i am skeptical if they actually maintain constant voltage of 5 volt with time

 

[newlash09]

Are you using the CVT from Bhurji? Is there a CVT that will take care of 1,2,and 3? For 4, in my audio chain out of Little Dot MK II pre-amp looks to be having a transformer already, CS 851C CDP and Allo Digione, only the Digione is using a SMPS power, as such only that would be requiring a Galvanic Isolator right? I am also checking if powering the digione with power banks that claim to provide 3 amp / 2.4 amp in a single output port can be an option although i am skeptical if they actually maintain constant voltage of 5 volt with time

Hi again haisaikat...

Iam actually using a CVT I got off Amazon. Below is the link.
https://www.amazon.in/gp/aw/d/B07KYTLQMW/ref=ya_aw_od_pi?ie=UTF8&psc=1

As regarding the isolation transformer the search continues. This CVT will cover the requirement to keep the voltage steady and also shaping of the sine wave. But it does not offer complete power isolation. So will need an external isolation transformer again.

As regards achieving no.4, if you can feed off the SMPS for the Allo from different wall socket, then it's high frequency return noise will be dumped into a different wall point. And when that travels to your hifi rig, it will be stopped once you have a isolation transformer in place.

 

[haisaikat]

As regards achieving no.4, if you can feed off the SMPS for the Allo from different wall socket, then it's high frequency return noise will be dumped into a different wall point. And when that travels to your hifi rig, it will be stopped once you have a isolation transformer in place

This is a good idea.

I see you are also using a isotek power cable, is that for all devices or particular ones?

 

[antoniodias]

Ajay I think you should wait a while as @ GeorgeO states. Possibly it will now run fine since you have changed all your old sockets to a new branded ones. Best of luck in your decision making

 

[newlash09]

This is a good idea.

I see you are also using a isotek power cable, is that for all devices or particular ones?

Hi again...

I only brought 2 isotek power cables of 1M each. So they are presently feeding the dac cum pre amp and Metrum Ambre. Ideally power cables are supposed to make the biggest difference on power amps. Unfortunately my cables are too short for that at the moment. Will add longer power cables in the future to drive the Poweramp. But the more pressing issue for me right now, is to get a dedicated line from the mains to feed the power amp. And my present in room wiring is unable to cope with the current draw of the amp on powering up.

 

[eddie_fox]

Hi all,

Sorry for re-raising the extensively discussed issue.... CVT vs Online UPS

I have been working without either of these products, but just with a V-Guard Crystal Plus stabiliser for the last few years. I had, fortuitously, not had any problems, till about a few months ago. My power amp section developed an issue and one of the channels needed replacement. Now, the other channel also developed an issue and is being replaced. I borrowed an amp from my friend to test my new speakers and his power amp got damaged as well (one channel). The fuses were blown and replacing them has not restored the functioning. We strongly suspect that these are power related issues in my apartment.

I am now forced to consider buying equipment to avoid further damage to my system. The choices I have are:

CVT + Power Conditioner by a company called Rontek
or
Online UPS - Not sure of the brand yet, as I am still researching.

Some key considerations in my case:
1. My setup is in the living room and I have to keep this power protection unit in the same room (and maybe quite close to the speakers etc.)
2. I am alright with or without backup time for shutdown

Can you please advice which of these products match my requirements?

P.S - I have read all the posts in this thread thoroughly, but am still confused which of the two (CVT or Online UPS) is better. Sorry.

Any help will be greatly appreciated.

 

[blackscorpio]

Hi all,

Sorry for re-raising the extensively discussed issue.... CVT vs Online UPS

I have been working without either of these products, but just with a V-Guard Crystal Plus stabiliser for the last few years. I had, fortuitously, not had any problems, till about a few months ago. My power amp section developed an issue and one of the channels needed replacement. Now, the other channel also developed an issue and is being replaced. I borrowed an amp from my friend to test my new speakers and his power amp got damaged as well (one channel). The fuses were blown and replacing them has not restored the functioning. We strongly suspect that these are power related issues in my apartment.

I am now forced to consider buying equipment to avoid further damage to my system. The choices I have are:

CVT + Power Conditioner by a company called Rontek
or
Online UPS - Not sure of the brand yet, as I am still researching.

Some key considerations in my case:
1. My setup is in the living room and I have to keep this power protection unit in the same room (and maybe quite close to the speakers etc.)
2. I am alright with or without backup time for shutdown

Can you please advice which of these products match my requirements?

P.S - I have read all the posts in this thread thoroughly, but am still confused which of the two (CVT or Online UPS) is better. Sorry.

Any help will be greatly appreciated.

IMO:
1. Servo stab + CVT for the ultimate safety, can be used for all types of equipment's.
2. (Online) UPS for backup (not recommended for power amps, AVRs. Best for TV, must for projector)

 

[raghupb]

A decent ups, offline or online, will suffice for most equipment.
I have a 800 VA inverter with battery back whole house. Very basic model.
Works for my rig. Marantz AVR and IA blink when power switches over.
Other equipment keeps playing on.
TV blinks sometimes. I guess it depends on battery charge levels
Cheers,
Raghu

 

[square_wave]

We strongly suspect that these are power related issues in my apartment.

Hi Eddiefox, This problem is very real. Also, if you live in an apartment, you have very less control over the wiring standards and the “generator or power backup kicking in situation “. There are no standards that are adhered to. I have met a few of these clowns who call themselves “electricians” in apartments. Don’t even get me started on it. That is why I bought a double conversion ups many years back. You need something like that or a CVT / Servo controlled stabilizer along with very high quality protection devices from furman etc.

I will never recommend anything from V guard for high end av equipment.

Regular home inverter systems are a big "No" for av gear.

 

[eddie_fox]

Thank you for your inputs.

Just to add, these are the current options:

Option 1 - 3KVa Servo Stab - 8000 INR (approx.)
Option 2 - 3KVa Servo Stab + Isolation transformer - 20,000 INR (approx.)
Option 3 - CVT + Power Conditioner - 28,000 INR (approx.)
Option 4 - 3KVa Online UPS (APC/Emerson) - 29,000 INR (approx.)

Any votes on the options? Any other suggestions?

Thanks

 

[square_wave]

I only have experience with double conversion online ups from Apc. Emerson, Leibert, Eaton are all good brands. Servo stabilizers are mechanical in nature so someone who has technical expertise in their suitability should chime in. I used to own a Vertex servo stab in the past. It used to make a sound whenever there was a fluctuation. It worked fine though with my odyssey stratos and preamp. A friend's amp blew because of mechanical failure of the servo stab though. Not vertex...something else. But I sold it in a jiffy !

No experience with CVT or Isolation transformer.

 

[blackscorpio]

IMO:
1. Servo stab + CVT for the ultimate safety, can be used for all types of equipment's.
2. (Online) UPS for backup (not recommended for power amps, AVRs. Best for TV, must for projector)

Sorry, it is Servo + Isolation trafo and the 3rd option must be CVT alone.

Considering, CVT being noisy I will rule it out, unless it can be placed outside the HT/stereo room. But this is the best option for protecting your gear, I read.

UPS is not recommended for amps/int/AVR, it is ruled out for the whole setup but I guess one must have a rather smaller capacity just for the projector/TV.

Servo + Isolation is my preferred setup.

Disclaimer: I have no electrical background, this is from the bits & pieces I read online.

 

[square_wave]

UPS is not recommended for amps/int/AVR, it is ruled out for the whole setup but I guess one must have a rather smaller capacity just for the projector/TV.

Can you tell us more about this ? From my research in the past, from a quality and protection context, power regenerators are the best option. Among ups systems, only " double conversion online " does this. This type of ups takes the input AC and then converts it into DC, then it reconverts it back to a pure sinewave AC. Your equipment is never connected to the input AC current at your home. High end regenerators like PS audio etc.. are pretty much doing the same thing. The only difference is that they take it to the next level when it comes to quality of the output stage. They are of course better but they come at a price.

What kind of ups systems have you tried out? What was your experience ?

Can you talk more about servo + isolation ? Will the isolation transformer be kept before or after the servo ? What is the benefit from a technical standpoint ?

 

[blackscorpio]

Can you tell us more about this ? From my research in the past, from a quality and protection context, power regenerators are the best option. Among ups systems, only " double conversion online " does this. This type of ups takes the input AC and then converts it into DC, then it reconverts it back to a pure sinewave AC. Your equipment is never connected to the input AC current at your home. High end regenerators like PS audio etc.. are pretty much doing the same thing. The only difference is that they take it to the next level when it comes to quality of the output stage. They are of course better but they come at a price.

I never thought of comparing the online UPS & regenerators, so I googled, here is the top result :

PowerPlant vs. Double Conversion UPS

For home theater, too, a UPS makes sense - projector bulbs do not like suddenly losing power. It can impact their overall lifespan. As you said, it’s tough finding apples to apples specs. I checked with one of our engineers and we don’t measure common and normal mode noise in our Power Plants.

forum.psaudio.com

BTW, I don't have any technical expertise to discuss or explain the topic. As I stated earlier, the statements I made is my conclusion of what I read, bits & pieces, on the internet.

please add the salt to your pleasing. lol.

What kind of ups systems have you tried out? What was your experience ?

I had an Eaton 3KVA online UPS only for HT. I didn't notice any change after removing UPS. Stereo, I never had any UPS.

Can you talk more about servo + isolation ? Will the isolation transformer be kept before or after the servo ? What is the benefit from a technical standpoint ?

Mains -> Servo -> Isolation -> Equipment

From what I read, Servo stabilizes the main input current but it does so through mechanical servo motor. Isolation trafo basically isolates the equipment from the direct connection with main input, isolation trafo has two winding's, primary & secondary, and there is no contact between the two. Current is transferred between through magnetic flux. So it makes the power lot cleaner. In laymen terms we can say it regenerates or say it generates electrical current from magnetic flux, I guess.

Disclaimer: Not an electrical engineer, I am as well trying understand/grasp things from what I read online. so, I might be totally wrong. I would appreciate if the more knowledgeable correct me.

 

[square_wave]

@blackscorpio , thanks for the quick reply. I have been following ps audio for a while. I got the context.
To summarise :

1. You could not find any difference in the HT before or after a double conversion ups was in place.
2. You have not tried a double conversion ups in your stereo.

Thanks for the info about servo + isolation trafo. Interesting. Have you tried this in your system ? How did it go ?
If there are people who have tried this, it would be awesome if they can also chime in.

I have been led to believe the following after many experiments and talks with people who have tried all these.

- For amplification devices, connecting to the wall socket directly gives the best performance. But this works if you have relatively clean power at your home. In cases of very bad quality power, power generators of very high quality works best. When I tried a servo in my setup in the past, I could not hear much difference. That was when I was living in an independent house. When I moved to an apartment, the APC ups made the sound a bit cleaner. So, all this need to be taken into context. I have never tried a servo with isolation trafo, so no comments.

- For digital and preamps, there are too many products out there. Power regenerators, conditioners .. all of them make a difference. But you go to try them to take a call.

This is very good for gear rated below 100 watts.

Monarchy-audio.com