Does this amp consume >75W of real power? - diyAudio
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Old 25th October 2011, 07:01 PM   #1
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Default Does this amp consume >75W of real power?

Hi,

The Blackstar series one 200 says its a 200W amplifier.

Blackstar Series One 200 Guitar Amplifier

But does that mean 200 VA (apparent power) or is it 200W of real power?

-Also, does it use a Power Factor Correction stage?
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Old 25th October 2011, 07:10 PM   #2
kevinkr is offline kevinkr  United States
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Questions such as this are best addressed to the manufacturer I would think??

The power specified is the amplifier's output power which is specified as 200W so power consumption would be much higher than this at full output power.. Since it is presumably a class A/B amplifier in normal use and has lots of filaments to heat I would assume real power consumed is going to be well in excess of 75W..

I've yet to see a tube amplifier that uses power factor correction. The supply is probably a traditional power transformer into a FWB or similar.

Not sure what your angle is here..
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Old 25th October 2011, 07:24 PM   #3
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I have read EN61000 regulations from start to finish and there is no exemption on Power Factor Correction for Audio Power Supplies for guitar amps.

So i cannot understand why virtually NOT ONE single guitar amp in the world with power above 75W uses Power Factor Correction.

Is it a case of, as long as every body disobeys the regulations, then we're all OK?
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Old 25th October 2011, 07:30 PM   #4
kevinkr is offline kevinkr  United States
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Most large solid state power amplifiers for HIFI and PA don't either, and given the production volumes probably won't.
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Old 25th October 2011, 07:46 PM   #5
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Thanks, as you know, EN61000 laws on Power Factor Correction do not exempt power supplies from PFC simply because they have low sales volumes.

I am just wondering how the Audio fraternity has managed to ride roughshod over a regulation that is slavishly adhered to by the rest of the world?
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Old 25th October 2011, 08:54 PM   #6
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Quote:
Originally Posted by eem2am View Post
Thanks, as you know, EN61000 laws on Power Factor Correction do not exempt power supplies from PFC simply because they have low sales volumes.

I am just wondering how the Audio fraternity has managed to ride roughshod over a regulation that is slavishly adhered to by the rest of the world?
Because there's no such requirement - why are you obsessed by PFC?.

PFC is mostly only relevent to large industrial plant - although modern TV's now tend to have PFC correction PSU's.

But i don't think anything else domestic has PFC?.
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Old 25th October 2011, 09:11 PM   #7
kevinkr is offline kevinkr  United States
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Quote:
Originally Posted by Nigel Goodwin View Post
Because there's no such requirement - why are you obsessed by PFC?.

PFC is mostly only relevent to large industrial plant - although modern TV's now tend to have PFC correction PSU's.

But i don't think anything else domestic has PFC?.
Most better computer PSU do at least here..

I think it is also the case that most audio gear runs for a limited amount of time each day or even week as compared to most computers and TV sets. (Diminishing returns at high expense and some possible compromise in reliability - more parts and complexity afterall.)
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Old 25th October 2011, 11:01 PM   #8
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PFC isn't only needed to pass the regulations.........for a SMPS with more than a few hundred watts of CONTINUOUS output power, you cannot pass mains harmonic current limits, and keep input electrolytic cap ripple current inside limits with a non PFC supply.

so you actually need PFC if you have say 250W+ of continuous output power.......not just to pass the PFC regs.

...just imagine how massively high your RMS mains input current is if you do not have PFC with an offline SMPS with 250W+ of continuous output power.
...and then your common mode choke etc needs to be rated for this.

So if you have high continuous power, then you've no choice but to use PFC...regardless of the regulations
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Old 25th October 2011, 11:45 PM   #9
mimungr is offline mimungr  United States
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I'm no expert, but I believe the 75W threshold is based on average power consumption during normal operation, not the maximum rated power.

I think Blackstar could argue that under normal use, power consumption is less than 75W.
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Old 25th October 2011, 11:55 PM   #10
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A pair of KT88's will put out 100W according to the datasheet, four should do 200W.
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