Will Step down transformer affect HiFi's performance??

kams

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Friends,

This question is hitting me whenever I think abt electronic Item purchase in USA.

Friends Tell me "Will Step down transformer affect High end HiFi's(120V) perfomance?"......If it is, what is the performance difference compared to standard Voltage(230V) HiFi Items?

Is there any good&economy brand transormers available in India?..
What is the role of Voltage stabilizer and UPS in Hi Fi setup?....

guidance please..

Thanks,
Pandiyan
 
Hi Pandiyan
There may be an affect if your step down rating is not much higher. For .e.g. if you have an amp with max consumption at 500W, you should get a transformer that is rated much higher (remember there is an inefficiency also associated with the transformer itself). Even then, your performance may likely deteriorate. However, how much you can make out/hear is dependent also on the quality of the setup that you have...ranging from a simple receiver to a higher end receiver/amp.
A Power conditioner is used to remove noise from the line and a UPS is used to provide uninterrupted power supply :D although you can get a good one and use it as a UPS + a top notch power conditioner.

cheers
 
Let us get some fundamentals in place.

Electricity is all about the flow of electrons in wire. "Voltage" is a measure of how hard the electrons are pressing to get through--it's like water pressure in a pipe, or like the rotational force in our car's wheels. "Current," measured in amps, is a measure of how fast the electrons are flowing--it's like the gallons-per-minute flow in a pipe, or the feet-per-minute rate of spin of the tires on our car. Total power delivery, in an electrical circuit, is measured in watts, which are simply the volts multiplied by the amps; in the same way, the total power delivered by the car in our example is the amount of rotational force delivered by the wheels, multiplied by the speed of rotation. A number of watts may represent a very high voltage with relatively low current (such as we see in high-tension power lines) or a low voltage with very high current (such as we see when a 12-volt car battery delivers hundreds of amps into a starter).

To all this let us add a new dimension. This dimension is called 'frequency'. Unlike direct current (DC) that flows in one direction all the time, alternating current changes direction (represented as +ve and -ve) at a predetermined cycles per second. In the US it is 60 cycles per second or 60Hz. In India, it flows in 50 cycles per second or 50Hz.

How does this affect us? Well most AC equipment such as tube lights, heaters, and motors have been designed to work with these cycles. Are you aware that a tube light flickers (comes on and off) at the same frequency as the AC current?

What does this mean to me? Well, if you take a US made motor designed for 60Hz and run it in India at 110 volts but at 50Hz, it just wont even turn or at best will turn erratically.

Step down transformers, as with any transformer, are usually around 96% efficient. They can never be 100% efficient as there is loss of energy and current in the windings. But the catch is most step down transformers do not worry about frequency. So if you take a step down transformer and convert 230 volts to 110, what you will get is 110 volts but at 50Hz.

Now we come to the best part. Your audio equipment should not be affected at all? Why. Simply because all audio equipment work on direct current. Power supplies inside the audio equipment contain a TRANSFORMER which converts the mains AC supply to a safe low voltage AC. Then the AC is converted to DC by a bridge RECTIFIER but the output is varying DC which is unsuitable for electronic circuits. So the next step is SMOOTHENING of the voltage. This is performed by a large value electrolytic CAPACITOR connected across the DC supply to act as a reservoir, supplying current to the output when the varying DC voltage from the rectifier is falling. Even this will only supply DC current with small ripples in voltage that yet cannot be fed to the electronic circuits. So a last step is a REGULATOR. This is usually an IC that consists of a zener diode regulator and resistors. Irrespective of what voltage is fed to the diode, it always sends out constant voltage that can be fed to the electronic circuits.

Ideally you should try to get equipment that can take both 110 and 230 volts at 60 and 50Hz respectively. This way you eliminate the need to bring in another step in your supplying power to the audio equipment. For example literally every mobile phone charger can be used across the world without any hassle as they can switch between 230 and 110 volts. These would generally be rated as 100-240~ with frequencies FROM 50 TO 60Hz.

Since the HiFi equipment does an internal conversion from AC to DC and from high voltage such as 110/240 to somewhere around 5 to 25 volts, most equipment can, by themselves, perform well with mildly varying input voltages (voltage fluctuation). So if you do put a step down transformer between your power supply and the equipment, it should not make too much of a difference to the equipment. If the frequency is not properly managed, highly sensitive parts such as DC motors (in a CD player) could be affected. This is where PSRR of the equipment's power supply plays an important part.

Why are we then talking about stabilisers and UPS? Most equipment manufactured in the US, Europe and other advanced countries depend upon a stable power supply that does two things - ONE they supply power without fail; and TWO have very low fluctuation usually +/- 5 volts. In India, unfortunately, the power supply is both very erratic, and falls in voltage as the power is withdrawn by the consumers. For example, let us assume there is a mela or a political program running near your house. This will draw huge amounts of current from your supply albeit for a short time. When this happens, the power supply to your house will be affected by a huge drop in voltage as the EB is incapable of compensating for the additional load. In addition, at times, because of low production (as compared to demand) the EB will deem it fit to present you with a power cut.

A step down transformer that is given erratic power supply will in turn supply erratic voltages to the power supply of the audio equipment. This will put a strain on the power supply's capability to generate steady DC voltages sometime leading to a fuse blowing up or the whole power supply burning out.

Another important factor to understand and build for is good earthing. Many US and European equipment are earthed to the body of the equipment. You might get mild shocks when you touch a live equipment. Secondly the static electricity created by a equipment not properly earthed could create electro magnetic waves that could affect nearby equipment. In TV you will usually see this as noise lines moving across the screen at an angle of 45 degrees or more. Good earthing and line filters will help remove this problem.

I am showing below an interesting article from a US based magazine called The Audio Critic. Their 26th issue had an article on the 10 Biggest Lies In The Audio Industry.

The 8th Biggest Lie in Audio

The Power Conditioner Lie


Just about all that needs to be said on this subject has been said by Bryston in their owner's manuals:

"All Bryston amplifiers contain high-quality, dedicated circuitry in the power supplies to reject RF, line spikes and other power-line problems. Bryston power amplifiers do not require specialized power line conditioners. Plug the amplifier directly into its own wall socket."

What they don't say is that the same is true, more or less, of all well-designed amplifiers. They may not all be the Brystons' equal in regulation and PSRR (*), but if they are any good they can be plugged directly into a wall socket. If you can afford a fancy power conditioner you can also afford a well-designed amplifier, in which case you don't need the fancy power conditioner. It will do absolutely nothing for you. (Please note that we aren't talking about surge-protected power strips for computer equipment. They cost a lot less than a Tice Audio magic box, and computers with their peripherals are electrically more vulnerable than decent audio equipment.)

The biggest and stupidest lie of them all on the subject of "clean" power is that you need a specially designed high-priced line cord to obtain the best possible sound. Any line cord rated to handle domestic ac voltages and currents will perform like any other. Ultra-high-end line cords are a fraud. Your audio circuits don't know, and don't care, what's on the ac side of the power transformer. All they're interested in is the dc voltages they need. Think about it. Does your car care about the hose you filled the tank with?

(*) Power supply ripple rejection ratio (PSRR) is a measure of how well a circuit rejects ripple coming from the input power supply at various frequencies and is very critical in many RF and wireless applications. In the case of an DC linear voltage regulator (LDO), it is a measure of the output ripple compared to the input ripple over a wide frequency range (10 Hz to 10 MHz is common) and is expressed in decibels (dB).
 
Venkat,

Thx a lot for your wonderful reply .... It is like a mini seminor on Current conversion...It reminds my Physics degree !!!...I appreciate it..Great !!!

Odyssey, Thx 4 u'r reply aslo..

Pandiyan
 
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I forgot to add some conversion factors. This has been explained to some extent by Odyssey, but let me see if I can make is clear.

Generally speaking KW and KVA are units of power. The ampere is a unit of current. If you divide power by the voltage involved, you can determine the current involved, in amps.

Power (watts) = volts x amps

A volt-amp(vA) is a watt (W). (A volt times an amp is a watt.)

The main difference between watts and volt amps is that the watt rating determines the actual draw of power from a power source and the heat generated from equipment. The VA rating is used for sizing equipment such as circuit breakers, stabilisers, wiring, and UPS. The VA rating is normally equal to or higher than the watt rating, as it includes the power factor in its calculation.

Power Factors

The Power Factor is a calculation used to account for the difference in power supplies used to convert AC power into DC for use in electrical appliances. There are two types of power supplies - the capacitor input supply and the power factor corrected supply.

Power factor corrected supplies are used in most high end equipment, and have a ratio of 1W:1VA, allowing a very simple calculation for scaling electrical equipment and UPS. Thus, in theory, if your power factor is 1:1, and your load is 100 watts, you need an UPS that is rated at 100vA or 0.1KvA. You would be loading the UPS to 100% of its rating.

Older electrical equipment, as well as most audio and video equipment use capacitor input power supplies and have a power factor anywhere from 0.55 to 0.75 times the VA rating.

Typically when scaling a UPS for use you will use a 60% load factor on the UPS. If you overload a UPS it is almost certain to fail during a power outage, as the draw on the batteries will exceed the capacity of the UPS. Most new UPSs will automatically go into battery bypass when an overload condition occurs. The 60% load factor accounts for the high probability that most of the equipment drawing power through the UPS will be of a category that has a power factor of between 0.55 and 0.75.

Let us assume we have a brand new amplifier whose power consumption is shown as 500 W. You divide this by 0.60 (Point Six Zero) to get the KvA of the UPS/Stabiliser. Thus the load capacity on the UPS for your amplifier will be 500/0.60 which equals to 833 vA or 0.8KvA.

For step down transformer, all you have to compensate for is the energy loss due to heat dissipation, which is usually around 10%. So if your power consumption is 1000 watts, make sure that the step down transformer is rated at 1.10KvA.
 
ILet us assume we have a brand new amplifier whose power consumption is shown as 500 W. You divide this by 0.60 (Point Six Zero) to get the KvA of the UPS/Stabiliser. Thus the load capacity on the UPS for your amplifier will be 500/0.60 which equals to 833 vA or 0.8KvA.

.

I think you need to revisit the calculation. For 500 W power consumption, current rating would be 2.71 A which could be steady state current drawing, while during cold start , the amp draws heavy current (called as In rush Current) as well as while playing complex / dynamic music the amp again draws much higher current than this 2.71 A!

Your calculation suggests putting 0.8 KVA UPS to power this amp (500 W power consumption) , means this UPS can supply 3.48 A, which is not enough. In order to take care of In rush current and dynamic current requirements one has to provide at least 3 times the normal (steady State)current . In this example it should be 2.71 x 3 = 8.13 A!

Now after applying that UPS safe opering margin of 60%, this becomes 13.55 A! Which is 3.11 KVA UPS.

Put anything less, amp will work but dynamics will suffer.

And one more important thing here if it is UPS then it must be of Pure Sine wave UPS. (Not the quasi / Stepped Sine wave type). And 3 KVA Pure Sine wave UPS will cost a bomb!!

One can power HifI compoent through Servo Voltage Stabilizer with optional Ultra Isolation Trasformer. (Calculations reamins the same as I explained above).

Hope this helps.

SUhas
 
Thanks SuhasG. You could be right.

But then again, the figures I mentioned were under the assumption of peak or maximum usage. Most amplifiers would mention clipping power (maximum continuous power/channel) and this is the figure we have to take to do our calculation.
 
Sorry I also agree that an UPS will cost a bomb. Please replace all 'UPS' with 'UPS/Stabiliser'.
 
This brings up a question in my mind - will a AV receiver work well with inverters without any issues? I have already blown up a cooler and a spike guard (running pc speakers) but blowing up a av receiver wil be a costly affair.
 
Venkat,

Very nice write up mate. I think its the audiophelia (much abused term, I know:rolleyes:) inside the head that do not let us go by logic and steer us into believing something that only the ??golden ears? can experience!

Quote-
An example of this type of marketing, and the associated reviews in magazines, is the $1499 power cord, for which the reviewer states that "The choice of power cord one makes to transmit AC over the final feet to a component has the potential to be the most influential sonic link in a music system's power chain.

Roger Russell??a former engineer and speaker designer for McIntosh Labs??describes the introduction of expensive speaker wire brands, and critiques their performance in his online essay called Speaker Wire - A History.


In pursuit of happiness ?? bliss!

Check this out, incase you want to get more confused:cool:
Speaker Wire
 
This brings up a question in my mind - will a AV receiver work well with inverters without any issues? I have already blown up a cooler and a spike guard (running pc speakers) but blowing up a av receiver wil be a costly affair.

I am surprised that an inverter blew up anything. An inverter, since it provides power stored and transformed from a battery should provide the cleanest power possible. There should be no spikes, and no fluctuation. Only thing is at the end, when the batteries are dying out, you will have a continuous drop in voltage till the system dies.

Can you use an AVR with an inverter? I would say no unless you have an inverter that can take a huge load. If you read the specifications of the inverter, it will be mentioned what kind of load it can take. Most residential inverters are made to keep a couple of fans, and a couple of tube lights burning till the mains power come back. Remember amplifiers and AVR consume huge loads, particularly when they are playing at high volumes. A combination of an AVR, a DVD Player, and a TV will drain your inverter quite quickly.

The best combination is to run your AVR through a stabilizer, and a power conditioning unit such as line filter, and run the system only when you have mains power.
 
Thanks SuhasG. You could be right.

But then again, the figures I mentioned were under the assumption of peak or maximum usage. Most amplifiers would mention clipping power (maximum continuous power/channel) and this is the figure we have to take to do our calculation.

I go by the Amp's fuse rating.

Most (or all) amps are provided with Slow Blow type fuse (those are indicated by letter 'T' [Time] associated with its current and voltage rating) .

Why 'Slow blow' ? As I mentioned above amps take higher current at cold start (that is when you swict on the amp ) as well as during delivering complex music sections, while normal steady state current is much lower.

If a fuse is fitted in accordance with the steady state current , it will blow during start up and dynamic deliveries, while fuse rated as per the In rush current won't protect the amp when it operates at steady state current (most of the time. )

Slow blow fuse can take a momentary excess current load than its rated current this helps to tide over in rush current demand , hence the fuse won't blow while under normal conditions if the amp tries to draw excessive current over a longer period the fuse blows and protect the amp.

Slow blow fuse can withstand 2-3 times normal rating that is printed on the fuse. So take this steady state current fuse rating and mutiply by 3 to arrive at worst case current drawn by the amp. Then multiply it by 230 to get KVA rating. Then multiply it by 1.2 to comensate for power factor, assuming that amp's input transformer is having 0.8 lagging pf. This will give you a correct estimate of actual KVA requirements , agian multiply it by 1.3 to have some safty buffer. Now you know what KVA stab to order!

Here I am considering only Amp, if you have any other current hungry equipments also to be powered then add respective VA requirements.



My amp takes 0.8 A under steady state and probably 3 A worst case, I have provided a 3 KVA Krykard servo voltage stabilizer which can supply around 13 Amp.




Hope this helps.


SUhas
 
Hi Venkat
Thanks for your insightful posts on the forum.
I am surprised that an inverter blew up anything.
Even I was surprised at this. I have microtek 800Va inverter coupled to a 190Ah battery and I get good backup even with 29 inch CRT on for most of the time for last 3 years without any issues. It also manages to run a semi auto washing machine and mixer!

Things changed when i bought a cooler last year and when there was a power cut, the cooler started making strange noises. I immediately switched it off and it saved the cooler. But the next time in my absence, it just blew up. The cooler had problem working on square wave I guess.

Other incidence was when I was running my 2.1 speakers though a spike guard and there was a power cut. I guess it was too much to handle for the inverter with whatever was happening in the spike guard and it started beeping abruptly. After a while the spike guard gave off. I didnt realize it were the speakers that were causing the problem.


Now the inverter is always switched off so that in case of power cut I have sufficient time to switch off these sensitive things before I switch it on.

Hence, every time I have to buy a piece of electrical equipment I have this question - whether it will work on inverter!!
 
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I go by the Amp's fuse rating.

Most (or all) amps are provided with Slow Blow type fuse (those are indicated by letter 'T' [Time] associated with its current and voltage rating) .

Why 'Slow blow' ? As I mentioned above amps take higher current at cold start (that is when you swict on the amp ) as well as during delivering complex music sections, while normal steady state current is much lower.

If a fuse is fitted in accordance with the steady state current , it will blow during start up and dynamic deliveries, while fuse rated as per the In rush current won't protect the amp when it operates at steady state current (most of the time. )

Slow blow fuse can take a momentary excess current load than its rated current this helps to tide over in rush current demand , hence the fuse won't blow while under normal conditions if the amp tries to draw excessive current over a longer period the fuse blows and protect the amp.

Slow blow fuse can withstand 2-3 times normal rating that is printed on the fuse. So take this steady state current fuse rating and mutiply by 3 to arrive at worst case current drawn by the amp. Then multiply it by 230 to get KVA rating. Then multiply it by 1.2 to comensate for power factor, assuming that amp's input transformer is having 0.8 lagging pf. This will give you a correct estimate of actual KVA requirements , agian multiply it by 1.3 to have some safty buffer. Now you know what KVA stab to order!

Here I am considering only Amp, if you have any other current hungry equipments also to be powered then add respective VA requirements.

My amp takes 0.8 A under steady state and probably 3 A worst case, I have provided a 3 KVA Krykard servo voltage stabilizer which can supply around 13 Amp.

Hope this helps.

SUhas


Suhas:

We are both talking about the same thing. You can calculate the load from either amperage or from wattage, but both will arrive at the same volt amps. This is assuming that the load factor is the same.

As you mentioned, you can also calculate the load by multiplying the amperage with the voltage - either 110 or 230. Assuming the load factor is the same, you will arrive at the same results. In other words, amp*v/LF and W/LF will be the same.

Couple of things about your calculations:

1. If I am not wrong, a fuse will be rated not at steady state, but to withstand max load. In addition, the system at full load will be only 75 to 80% of the fuses's rated capacity. If this is not done, you will be changing the fuse everyday. Thus. the fuse itself has a good buffer. In addition, if it is a slow blow fuse, it is further capable of withstanding (as you said) 2 to 3 times it normal rated capacity during a in-rush.

2. In-rush and the need for a slow blow fuse is usually meant for lighting elements and motors where there is an inertia that has to be compensated for.

3. In a solid state electronics such as amp, the initial load when you switch on the system is only the quantum of energy needed to fill the capacitor and the time taken to do that. This quantum of energy should not strain the system beyond 150% of its normal load, and the time taken should be less than 10 seconds.

Though there is no harm, I do believe you are being overly cautious in calculating the load for the stabiliser. Actually providing for just the right capacity at the stabiliser end may be more prudent, as the stabiliser will trip or shut down in the event of a overload, thus protecting the expensive audio equipment.

Other than the fact that, in addition to the load factor, you are adding for a buffer at the fuse level, we are both talking about the same thing.
 
venkat, suhas....just out of curiosity (and a lot of gratitude)....what do you guys do for a living? i am seriously regretting dropping science after 10th standard....of course...if i'd taken science i would have regretted dropping humanities (and wouldn' have ended up being a lawyer probably).....so you can't really win :)

Suhas:

We are both talking about the same thing. You can calculate the load from either amperage or from wattage, but both will arrive at the same volt amps. This is assuming that the load factor is the same.

As you mentioned, you can also calculate the load by multiplying the amperage with the voltage - either 110 or 230. Assuming the load factor is the same, you will arrive at the same results. In other words, amp*v/LF and W/LF will be the same.

Couple of things about your calculations:

1. If I am not wrong, a fuse will be rated not at steady state, but to withstand max load. In addition, the system at full load will be only 75 to 80% of the fuses's rated capacity. If this is not done, you will be changing the fuse everyday. Thus. the fuse itself has a good buffer. In addition, if it is a slow blow fuse, it is further capable of withstanding (as you said) 2 to 3 times it normal rated capacity during a in-rush.

2. In-rush and the need for a slow blow fuse is usually meant for lighting elements and motors where there is an inertia that has to be compensated for.

3. In a solid state electronics such as amp, the initial load when you switch on the system is only the quantum of energy needed to fill the capacitor and the time taken to do that. This quantum of energy should not strain the system beyond 150% of its normal load, and the time taken should be less than 10 seconds.

Though there is no harm, I do believe you are being overly cautious in calculating the load for the stabiliser. Actually providing for just the right capacity at the stabiliser end may be more prudent, as the stabiliser will trip or shut down in the event of a overload, thus protecting the expensive audio equipment.

Other than the fact that, in addition to the load factor, you are adding for a buffer at the fuse level, we are both talking about the same thing.
 
venkat, suhas....just out of curiosity (and a lot of gratitude)....what do you guys do for a living? i am seriously regretting dropping science after 10th standard....of course...if i'd taken science i would have regretted dropping humanities (and wouldn' have ended up being a lawyer probably).....so you can't really win :)

Well, I am an Post Graduate in Economics, and I manage software companies. I have been in the software business for about 25 years.

Cheers
 
Just about all that needs to be said on this subject has been said by Bryston in their owner's manuals:

"All Bryston amplifiers contain high-quality, dedicated circuitry in the power supplies to reject RF, line spikes and other power-line problems. Bryston power amplifiers do not require specialized power line conditioners. Plug the amplifier directly into its own wall socket."

FYI, Bryston now markets the Torus power range of power conditioners and hence now no longer recommends against using one. Maybe they realised that their "high-quality, dedicated circuitry in the power supplies to reject RF, line spikes and other power-line problems" is not good enough???

Bryston Limited - Music For A Generation
Torus Power Audio/Video Power Conditioners with Isolation and Surge Suppression - Clean Power
 
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venkat, suhas....just out of curiosity (and a lot of gratitude)....what do you guys do for a living? i am seriously regretting dropping science after 10th standard....of course...if i'd taken science i would have regretted dropping humanities (and wouldn' have ended up being a lawyer probably).....so you can't really win :)

I am a post graduate in Electrical Engineering. I am in the domain of Control Systems Engg, Process Instrumentation and worked with several companies in India and abroadf for past 22 odd years . At present working as a Consultant to Indian's number one IT company.

I also have got 4 years of training in Indian Classical Music (both Vocal and Instrumental) under the guidance of Pt Arvind Gajendragadkar. I listen to Jazz, Indian Classical , Western Classical and regional folk music.

Apart form music my other interests are Photography, architecture and reading.
 
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FYI, Bryston now markets the Torus power range of power conditioners and hence now no longer recommends against using one. Maybe they realised that their "high-quality, dedicated circuitry in the power supplies to reject RF, line spikes and other power-line problems" is not good enough???

Bryston Limited - Music For A Generation
Torus Power Audio/Video Power Conditioners with Isolation and Surge Suppression - Clean Power

You are very correct awedeophile. They are marketing Torus power conditioners and most recent reviews of bryston gear are all done using Torus power conditioning.
In spite of all this i was surprised to find the same old '' connect our amplifiers directly to the wall outlet " in the manual of the 4 B amplifier i received last month.
Dont really know what to make of it.
Regards
 
Power conditioner does make a difference

I suggest disbelievers try this : take your TV (should be 29inches or bigger any size, and fed with a dvd video or clear high quality cable signal). Just add a power conditioner or power line filter of good quality. The picture difference is significant even if you have a clean/modern home power wiring in Mumbai or any big city. I suggest this because its easier to see the difference than hear it. Power cords supplied with modern TVs are good enough and replacing them wont change things.

The same way, you will be able to hear the improvement in sound only if you have a system costing over 10 lacs in my opinion, or else you have problems with noise and voltage in your existing inputs that need a conditioner/isolator+filter. But these things do make an audible difference, you have to try them to see if they help your situation or not.
 
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