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Constant voltage tarnsformers = bad for audio?

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suri

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Hi all,

are constant voltage transformers NOT to be used for audio repoduction equipment?:eek:
 

Kamal

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And that response should also help manupanjab to rethink whether he really needs a CVT.
 

Asit

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Hi,

I am a novice in this business (I am a physicist but a theorist, not having much idea about everyday applications), but if explained properly, I think I will be able to understand.

Please look at post #29 of the thread http://www.hifivision.com/audio-video-accessories/1144-suggest-voltage-stabilizer-3.html. Would someone explain to me what's wrong with a servo stabilizer in places like Kolkata where there are quite a bit of voltage fluctuations and spikes.

I have solid quantitative proof of this (i.e. voltage fluctuation), because in our office a Cray supercomputer is supported by two online UPS from APC each of 60 KVA. These UPSs are configured so that each time the power supply goes out of a certain range, it falls back on batteries. These fluctuations happen almost everyday several times and the UPS system reports to me through e-mail each time it happens. I live in the Institute housing and have the same power source.

As a result I have installed a 3KVA servo stab from Krykard with RFI/EMI filter and surge protection. In that same thread quoted above, you shall find the main features of this servo stab. In future, if I can afford it, I want to install an UIT in the chain.

I am sorry to be a bit impolite here, but I have read so many conflicting reports in this forum that even being a physicist I am confused (so I can imagine the state of a non-technical person), I would not settle for a bla-bla answer. Knowledgeable people, please please give solid arguments for one way or the other in a fashion that is understandable. Really this should not be at all difficult to understand. We are talking about very very basic physics here.
 

Asit

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Hi Cranky,

Thanks for a super prompt answer. I do not have a CVT, I have a servo based stabilizer.

It's too late now and I am very sleepy. I shall provide you with its main features at a later time. The question is if this (i.e. a servo based solution) makes sense in areas like the one where I live with power quality as I described.

I am not sure Suri was very particular about a CVT as such, my impression was that it was more general: whether a device that is designed to produce a constant voltage supply obviously with a given error (on the voltage stabilisation) like a CVT or a servo based stab is good for audio equipments.

BTW, how do you know the power quality is pretty good in your locality? My report says completely opposite.
 

venkatcr

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Asit,

In terms of preferences for pure power I would rate the following as good in the order shown below:

1. Regenerators. This isolates the equipment from the power source and delivers a completely clean output.

2. UPS that deliver enough KVA and pure sine wave output. They are kind of half way to a regenerator. BUT, for an UPS to be effective, they should have low tolerances and switch to batter power extremely fast. For the kind of ratings we look for such UPS end up costing 40 to 50K or even more.

3. Servo controlled stabiliser that deliver a voltage plus/minus acceptable limits. Companies such as Krykard, Aplabs, Audire, and Vertex make extremely good servo stabilisers that will protect your equipment and also clean power for it to work well. Since you also have EMI/RFI filters as well as Spike protection built in, your equipment are very safe.

The only issue with servo as against a UPS is that you cannot use your equipment when there is a power failure.

Also read post no. 29 in http://www.hifivision.com/audio-video-accessories/1144-suggest-voltage-stabilizer-3.html

Cheers
 
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suri

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Hi Cranky,I am not sure Suri was very particular about a CVT as such, my impression was that it was more general: whether a device that is designed to produce a constant voltage supply obviously with a given error (on the voltage stabilisation) like a CVT or a servo based stab is good for audio equipments.

Hi Asit,

i, actually, referred to a CVT as opposed to a servo stabiliser.
at the place where i work, CVT's are used, and i have noticed that when CVT's are switched on without a load, they make a resonant sound which progressively decreases as more amperage is drawn.

at home, only servos are used and their operation seems to be silent.

I have not seen or heard of CVT's being recommended for use in audio reproduction, and I have wondered about the reason - hence the post:)
regards
 

suri

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COULD THIS BE AN OPTION-

= BUY A HONDA PETROL ENGINE (SILENT) GENERATOR, locate it at a distance in a ventilated enclosure (for better sound attenuation) and use this as a dedicated power source for the audio reproduction equipment.

It seems to me that alternators should be able to supply clean sine wave power with adequate amps; further there would be isolation from (dirty) mains power lines, and there would not be surges in the supplied voltage.

if this is, indeed, a viable option, then, what VA should the generator be? any recommended ancillary equipment to be used between the generator and the audio reproduction equipment?
 

moserw

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Depends...
Suri,

I've been using APC for years and absolutely no problems. They offer lots of options but in this thread's context quasi sine wave and pure sine wave. The pure sine wave ones are also online UPS where they charge and discharge the battery continuously and all supply comes from the battery whereas the quasi ones will supply power from the mains, and the battery kicks in when the power goes off. The pure sine waves as stated are obviously expensive and also the best. I've been using the quasi sine waves ones for all my PCs and they offer great protection and SQ too is great.

COULD THIS BE AN OPTION-

= BUY A HONDA PETROL ENGINE (SILENT) GENERATOR, locate it at a distance in a ventilated enclosure (for better sound attenuation) and use this as a dedicated power source for the audio reproduction equipment.

It seems to me that alternators should be able to supply clean sine wave power with adequate amps; further there would be isolation from (dirty) mains power lines, and there would not be surges in the supplied voltage.

if this is, indeed, a viable option, then, what VA should the generator be? any recommended ancillary equipment to be used between the generator and the audio reproduction equipment?
 

odyssey

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Asit,

In terms of preferences for pure power I would rate the following as good in the order shown below:

1. Regenerators. This isolates the equipment from the power source and delivers a completely clean output.

2. UPS that deliver enough KVA and pure sine wave output. They are kind of half way to a regenerator. BUT, for an UPS to be effective, they should have low tolerances and switch to batter power extremely fast. For the kind of ratings we look for such UPS end up costing 40 to 50K or even more.

3. Servo controlled stabiliser that deliver a voltage plus/minus acceptable limits. Companies such as Krykard, Aplabs, Audire, and Vertex make extremely good servo stabilisers that will protect your equipment and also clean power for it to work well. Since you also have EMI/RFI filters as well as Spike protection built in, your equipment are very safe.

The only issue with servo as against a UPS is that you cannot use your equipment when there is a power failure.

Also read post no. 29 in http://www.hifivision.com/audio-video-accessories/1144-suggest-voltage-stabilizer-3.html

Cheers

Actually ask a local UPS vendor to build an online DOUBLE CONVERSION UPS. This means that the pure-sine wave generator is always feeding off the battery (irrespective of the state of the mains supply - ON or OFF). This would effectively give you both 1 and 2. A 1KVA should cost less than 20K. The battery power neednt be substantial - 5 to 10 mins to allow you to switch off gracefully..
One can add an isolation transformer if needed for a few Rs K more.

cheers
 

venkatcr

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A 1KVA should cost less than 20K. The battery power neednt be substantial - 5 to 10 mins to allow you to switch off gracefully..
One can add an isolation transformer if needed for a few Rs K more.

Agreed, but this only strengthens the point I made. Most of us are looking at 2 to 3 KVA, and that will work out to 50K or more.

Other than an projector, none of the audio or video equipment need to be switched off 'gracefully'. There will be no harm to the equipment if the power is cut off suddenly.

Cheers
 

venkatcr

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The pure sine waves as stated are obviously expensive and also the best. I've been using the quasi sine waves ones for all my PCs and they offer great protection and SQ too is great.

Moser, as has been explained by SuhasG a number of times, you can use a quasi sine wave UPS for equipment such as TV and PC that have SMPS. For audio and AV equipment that do not have SMPS, you need to supply a pure sine wave input.

Though there are UPSs that do this, ultimately it is a cost factor. You can spend close to a lakh on a regenerator, around 50K for a pure sine wave UPS, or something like 15K for a good servo controlled stabiliser.

Cheers
 

gobble

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Suri,

I've been using APC for years and absolutely no problems. They offer lots of options but in this thread's context quasi sine wave and pure sine wave. The pure sine wave ones are also online UPS where they charge and discharge the battery continuously and all supply comes from the battery whereas the quasi ones will supply power from the mains, and the battery kicks in when the power goes off. The pure sine waves as stated are obviously expensive and also the best. I've been using the quasi sine waves ones for all my PCs and they offer great protection and SQ too is great.

Arent you confusing line-interactive vs online with quasi-sine wave vs pure sine? I think both can be pure sine wave UPSes.

Regards.
 

odyssey

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Agreed, but this only strengthens the point I made. Most of us are looking at 2 to 3 KVA, and that will work out to 50K or more.

Other than an projector, none of the audio or video equipment need to be switched off 'gracefully'. There will be no harm to the equipment if the power is cut off suddenly.

Cheers

Hi Venkat
3KVA is a lot - not sure how many people need that. If its for things like inrush current, then switching on equipment one by one will take care of it. The cost for 2KVA is nowhere near 50K, I paid 17K for mine with an isolation transformer. A 2KVA was less than 30K when I enquired. If you dont care about the battery it should be cheaper.

cheers
 

moserw

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Depends...
Arent you confusing line-interactive vs online with quasi-sine wave vs pure sine? I think both can be pure sine wave UPSes.

Regards.

To my knowledge a line-interactive UPS is a step better than offline UPS. The power is filtered to be similar to pure sine wave, but not exactly and only results in better power conditioning. I am not too sure if line-interactive can be pure sine wave. If it is then I stand corrected (and something more learned today). Please let me know/correct me.

Either ways I don't have any pure sine wave at home. I asked the costs involved once for pure sine wave and decided to stay put with quasi sine wave. Maybe soon I will move to pure sine wave and see or rather hear for myself the difference in SQ.
 

manu4panjab

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in my house..,
i don't think constant voltage bad for audio

i have purchased 2 v-gaurd digi 200

and very happy with my decision :cool:

it gives me much clearer distinct sound
 

gobble

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To my knowledge a line-interactive UPS is a step better than offline UPS. The power is filtered to be similar to pure sine wave, but not exactly and only results in better power conditioning. I am not too sure if line-interactive can be pure sine wave. If it is then I stand corrected (and something more learned today). Please let me know/correct me.

Well atleast they advertise line-interactive products as pure sine wave.

>>> SU-KAM <<< Leading manufacturer of Power Products in India, Only Power back up company manufacturing world class UPS, Home UPS, Online UPS, Inverters, Batteries, Battery Chargers, Solar Products

So I assumed ...

Regards
 

Kamal

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what is UIT and how much does it cost?
Ultra Isolation Transformer.
Used to isolate mains noise.
Cost -Rs 4000/- for a 1 KVA model from a good company.
In places like where I live where there is negligible voltage fluctuation/voltage drop, this may be all that you may require.
 

anm

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thanks Kamal. So what I understand is that to keep mains noise out I need UIT. In a place where there is a stable power supply I need just that, and maybe a surge protection strip. What about EMI/ RFI filtering?

If the power supply is fluctuating, I buy a servo for constant voltage. And servo must be between mains and UIT. Is that correct?

Is UIT needed for amps also, or does it suffice to have it only for sources?

regards
 

Kamal

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thanks Kamal. So what I understand is that to keep mains noise out I need UIT. In a place where there is a stable power supply I need just that, and maybe a surge protection strip. What about EMI/ RFI filtering?
# Not really an issue, unless your house is very near a HT line/substation
If the power supply is fluctuating, I buy a servo for constant voltage. And servo must be between mains and UIT. Is that correct?
# Correct.

Is UIT needed for amps also, or does it suffice to have it only for sources?
# If the fluctuation is bad,then amps will also benefit;UIT's are not expensive ,compared to UPS's/Servo Stabs.
 
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