POWER GAMES:Servo Stabilizer,CVT or Online UPS?

[ajay124]

I have been using a Vertex Servo Stab 2kva (i have 3 of these for my various systems) for the past 3 years. They built these with better internal cabling (supposedly an audiophile mod). These are working great and in those occasions of power failure - the system just shut down - without any harmful consequences. I even have the Odyssey stratos extreme amp connected through the vertex, and though this amp. is a high current design - I have not personally noticed any detrimental effect on music - regardless of the connection either directly to the outlet or through the vertex. BTW I had my electrician run dedicated connections from the breaker to my listening room.
cheers
Sid

What do you perceive as the benefits of a servo stabilizer?
Is the sound quality impacted in any way?
Becomes better or worse?
Do the rf/emi filters make a difference?
Are you using any sort of surge protectors?

 

[borg]

in ordinary stabilisers there is an auto transformer with different taps and appropriate taps are selected by relays to correct the output voltage,out put variation can be as large as 50v(in digital stabilisers 10-15v) before the taps change

in servo the exposed windings of an autotransformer is connected by a moving brush controlled by a servo controlled motor, there is no tap jumping involved so the output voltage variation is minimal, you will get a precise output voltage,but this being a mechanical /moving device the correction is slow, you will not get galvanic isolation(like online ups) unless you buy an isolation transformer, a surge suppressor is also required because the correction is slow

 

[avidyarthy]

'Electricals' is a too much on 'if and buts' and 'compromise here to get something there' .....

I had checked on such threads here, before settling for a digital transformer. The only precaution I had taken .... for an operational peak load of 1.5 KW (seldom attained), I went ahead with the purchase of a 4 kVA unit.

All units, more so, the AVR is behaving sanely now. No shut-downs, indication-light fluctuations, minor distortions in sound etc .... now.

 

[sam9s]

what is your model number, It might be possible to adjust the sensitivity through the bundled software .

Its this ..

https://www.apc.com/products/resource/include/techspec_index.cfm?base_sku=SUA750JB&total_watts=50

Model no is : SUA750JB

 

[borg]

Its this ..

https://www.apc.com/products/resource/include/techspec_index.cfm?base_sku=SUA750JB&total_watts=50

Model no is : SUA750JB

it can't be , unless you are in japan,

so sua750 model dont have a sensitivity adjust at rear panel

then using powerchute software set the sensitivity to low

page 7 , user configurable items,

http://www.apcmedia.com/salestools/ASTE-6Z8LLF_R2_EN.pdf

 

[sidvee]

What do you perceive as the benefits of a servo stabilizer?
Is the sound quality impacted in any way?
Becomes better or worse?
Do the rf/emi filters make a difference?
Are you using any sort of surge protectors?

Ajay124 - my main concern is to avoid damage to the equipment due to constant fluctuating power - both brownouts and spikes. Secondly I do not want any current restriction. I think both of these needs are being met. Some answers to your questions:
1. I have not noticed any reduction in sound quality with the servo in the loop - symptoms that I looked out for - a slight haze, loss of resolution, compression/and or reduction in dynamics, increased noise floor etc.
2. I feel that the vertex is completely transparent in my system
3. I am sure that the emi/rf filters are helping to make the vertex sound transparent
4. I am using 2 surge protectors downstream of the vertex- mainly a PS audio duet for the music side and a monster hts5100 mkii for the HT.
5. when I use the odyssey stratos amp. i connect it directly to the vertex cause I am concerned of current restriction by the PS audio unit though they claim that this does not happen.
Cheers
Sid

 

[hifiashok]

If my existing set up is good enough,then should I refrain from buying anything and save myself the hassle of grappling with the fan noise of a UPS.

an inverter (usually) does not provide any power conditioning. it only offers a backup, that too a non-sine wave o/p (if we discount Su-Kam and/or any other manufacturer that claims this). the o/p when power us available is direct from mains w/o conditioning and when power is not available, is from the battery.

 

[sidlal]

Ajay, I was in the same spot when I bought my Krell Evo 302 Power Amp (max power consumption - 3.4KW) and 222 Pre Amp last year. Hope my experience is of help to you...

Spoke to tons of people in the power business but remained thoroughly confused with all the jargon, science and tall claims! Finally, I spoke to the Krell technician in the US (he was aware of the poor power supply in India) and he was rather helpful:

1. Power Outage: Needs no protection against as it will not spoil the power/pre amps - I have chosen to follow his advice and have not regretted it so far.

2. Voltage Fluctuation: suggested that a servo stabiliser would be sufficient and cheap. I tried the CVT and online UPS (upto 15KVA). However both tripped off as soon as I pressed the power button on the power amp. I finally bought a 5KVA servo (with no bells and whistles!) and that has been serving me well over the last year. It does make a noise each time there is a fluctuation so I have connected it near my Distribution Board and it cannot be heard in the listening room. The wiring runs internally from the DB to the stabiliser and then to the wall switches in my listening room for the amp/pre-amp.

3. Spike Protection: Was advised against using one as the Krells apparently have built in protection and they may limit the sudden power draw. I decided to be a little more cautious and installed an SPD (Spike Protection Devices) in the DB itself on the phase to which my equipment is connected. These were from Indo Asian. I faced a spike one evening while my system was on. My laptop's charger and a few bulbs blew (they were on an unprotected phase) but my equipment remained fully safe! Now I am installing the SPDs on the other two phases as well to protect the whole house. I have not witnessed any deterioration in the sound quality.

4. Noise Filters: Was strictly told to avoid them as Krell already has full power conditioning circuitry already built in. Followed the advice and have no plans to use one.

Lastly, I have ensured that all my connection sockets are secured well and plugs are not loose to help prevent spikes and shorts.

In all, I spent less than 10K and have not had any problems so far.

Hope the above helps.

I am rethinking my requirements and feel that basically what I want is surge protection,rf and emi filters and stable power between 230-240 at all times.I am not very comfortable with the idea of noise from the cooling fans.If we ignore online ups for the moment,the choice seems to be between doing nothing or opting for the Vertex Servo Stabilizer with or without their surge protector.Vertex is willing to build the stabilizer according to my requirements with filters,obo surge protector and sockets which will directly accept the power cables from the cdp,pre and power.No extension board,no isolation transformer.I would prefer to keep the chain small.Would the direct regulated power from the servo be superior to the double converted 'pure sine wave' power of the ups?Since there is no back up,the equipment would abruptly shut off in case of power failure.Is this kind of shutdown harmful for the system or does it make no difference?

 

[hifiashok]

I am rethinking my requirements and feel that basically what I want is surge protection,rf and emi filters and stable power between 230-240 at all times.I am not very comfortable with the idea of noise from the cooling fans.If we ignore online ups for the moment,the choice seems to be between doing nothing or opting for the Vertex Servo Stabilizer with or without their surge protector.Vertex is willing to build the stabilizer according to my requirements with filters,obo surge protector and sockets which will directly accept the power cables from the cdp,pre and power.No extension board,no isolation transformer.I would prefer to keep the chain small.Would the direct regulated power from the servo be superior to the double converted 'pure sine wave' power of the ups?Since there is no back up,the equipment would abruptly shut off in case of power failure.Is this kind of shutdown harmful for the system or does it make no difference?

between a servo and CVT, CVT any day! a servo, after all, is mechanical.

 

[arj]

an inverter (usually) does not provide any power conditioning. it only offers a backup, that too a non-sine wave o/p (if we discount Su-Kam and/or any other manufacturer that claims this). the o/p when power us available is direct from mains w/o conditioning and when power is not available, is from the battery.

A online UPS works differently from a regular UPS. here power is always converted to DC and then regenerated back to an AC sinewave (hence a double converting online UPS). Battery is used for additional power in order to give the rated supply always. so even if input power reduces, you get the rated output using the battery. it controls the Voltage, power and frequency and give a pure Sinusidal for most loads.

apparently the sinewave might not be that pure post 75% of the rated load

 

[hifiashok]

I tried the CVT and online UPS (upto 15KVA).

definitely a rating issue. a 15KV CVT would be humongous! and expensive. an o/l UPS even more so!

 

[hifiashok]

an inverter (usually) does not provide any power conditioning. it only offers a backup, that too a non-sine wave o/p (if we discount Su-Kam and/or any other manufacturer that claims this). the o/p when power us available is direct from mains w/o conditioning and when power is not available, is from the battery.

A online UPS works differently from a regular UPS. here power is always converted to DC and then regenerated back to an AC sinewave (hence a double converting online UPS). Battery is used for additional power in order to give the rated supply always. so even if input power reduces, you get the rated output using the battery. it controls the Voltage, power and frequency and give a pure Sinusidal for most loads.

apparently the sinewave might not be that pure post 75% of the rated load

was referring to an inverter in my post, not a UPS.

 

[sidlal]

The 15KVA o/l UPS was really humongous and expensive and somewhere inside I was hoping it would not work... My wife would have definitely walked out on me!

The huge current draw of the power amp at starting was something the UPS/CVT could not handle.

definitely a rating issue. a 15KV CVT would be humongous! and expensive. an o/l UPS even more so!

 

[ajay124]

@sidlal
I agree with your suggestion for keeping things simple and economical.Too much esoteric power conditioning probably harms rather than helps SQ.I too am moving away from an Online UPS as I don't want the hum of the cooling fans added to my listening experience.I may be over reacting to the hum as Sam9's is happy with an online UPS.It is possible that the hum is not so prominent in an HT set up.But in my two channel system,when I listen to classical chamber music I rarely switch on the ceiling fan in the summers.A chilled beer is anyway more effective,silent and enjoyable than an AC or fan.
I may opt for a modified Vertex 2kva Servo Stabilizer.With a German surge arrester made by OBO Betterman.Can be fixed anywhere,but I would prefer it inside the Servo.Also 3-4 sockets to directly attach the power cable from cdp/pre/power to individual sockets on the Stabilizer.No extension board or extra cables in the chain.I am extremely happy with the response from Vertex.
http://www.signetengineers.com/Class C Protection Recommended at input of Subdistribution Boards.pdf

 

[arj]

i agree..its not worth it buying blind... Since so many folks here seems to have good experiences with Servos, it may not be a bad idea .

 

[hifiashok]

definitely a rating issue. a 15KV CVT would be humongous! and expensive. an o/l UPS even more so!

The 15KVA o/l UPS was really humongous and expensive and somewhere inside I was hoping it would not work... My wife would have definitely walked out on me!

The huge current draw of the power amp at starting was something the UPS/CVT could not handle.

there is some gap here.....

CVTs are normally never more than 10KW, even so obscenely large.

O/l UPSs are available in the 15KW range but only with a 3 phase input (99%). most residences are usually 1 phase, i.e., not more than 7.5KW (since the meter is rated so).

 

[hifiashok]

a CVT is able to offer corrections within 100ms, like good quality o/l UPSs.

a (most) servo is rated @35ms/V!!

a servo's correction is not very accurate, i.e., it corrects beyond the need and then eventually stabilises to a close approximation.

a CVT provides arc protection, complete galvanic isolation, earth choking protection (where a servo would fail), etc. a servo would need a down line isolation tfr.

a transformerless UPS design is a compromise (from an indian power condition perspective). APC has had and continues to have a lot of issues since their designs, built from a US, etc., perspective, just does not cater to indian conditions. also, it MAY not be reasonable to expect them to normalise/modify the off_the_shelf models specifically for us. in a transformerless design, line noises and hi-V spikes are not catered for, esp. if these are over the rated range, meaning the necessity of a down line isolation tfr. this is the reason why most indian UPSs (non-transformerless) have one built in. building a transformerless design is cheaper and sleeker. what would the point be if it does not address the need that mandates the bulk of an isolation tfr!?

the typical reason for start-up in-rush current needs is owing to large capacitors in the amp.

 

[anm]

this is all getting very confusing!

 

[captrajesh]

a CVT is able to offer corrections within 100ms, like good quality o/l UPSs.

a (most) servo is rated @35ms/V!!

a servo's correction is not very accurate, i.e., it corrects beyond the need and then eventually stabilises to a close approximation.

a CVT provides arc protection, complete galvanic isolation, earth choking protection (where a servo would fail), etc. a servo would need a down line isolation tfr.

During 2nd Chennai HFV meet, a technical person was summoned to explain the basics of power conditioning. I remember them saying that Servo stablizer will be more suited for audio applications and a CVT would add hum. Don't know the technicalities involved as to how a CVT works and how and why the hum issue arises. Would like to hear your comment on that.

 

[borg]

A cvt works on principles of magnetic saturation and resonance, it is basically a large transformer with secondary winding tuned with a high voltage capacitor,there will be some humming noise, also by nature it cannot provide high output currents as in case of short circuit output falls to zero (excellent feature for other apps but i am not sure of implications in this application),

It is very reliable compared to a servo or online ups,(only part that can fail is a h.v capacitor), but it is susceptible to oscillations at low loads,

If the load conditions not much dynamic i would say CVT is an excellent choice, provided you can keep it away from your audio equipment to avoid the hum/harmonics pickup