FM Acoustics amps

[Mike Lavigne]

Hey Mike...is the measurement capacitance in microfarads? As in 400,000-500,000 microfarads in Gryphon amps? Presumably the amount of energy the amp can store, the greater the amp's ability to instantly react to large transients/energy draws without any sag?

honestly; i have no idea how microfarads compares to joules. but they both sounds like guys i have met.

Herve told me that the 458's hold 750 joules of energy in their capacitors, which is the same energy in a 45 caliber bullet. i simply wondered how that might compare to the 118's and expect they hold at least as much. but i am clueless as to really how that all works.

 

[Mike Lavigne]

The energy stored in a capacitor is given by the formula W = 1/2 x V x V x C , W , V and C being in joule, volt and farad.
The square dependence on V explains why tube amplifiers have reasonable energy storage in their capacitors with much less capacitance.

There is no proved relation between the amount of capacitance and the transient behavior of an amplifier. Some designers will even tell you that amplifiers with extra large capacitance are slow sounding. And electrolytic capacitors are "slow" - they must bypassed with other types, otherwise the power supply could not react fast enough to transients.

Power supply design is very complex and is linked with the overall design of the amplifier - most of the time the "audiophile rules" are mainly due to marketing pressure. Sorry to disappoint!

i am not disappointed. if amp design was only a numbers game then i would be very surprised.

with all the talk on this thread about super high power i was simply curious about how 750 joules of the 458's compared to the 118's.

 

[microstrip]

i am not disappointed. if amp design was only a numbers game then i would be very surprised.

with all the talk on this thread about super high power i was simply curious about how 750 joules of the 458's compared to the 118's.

Yes, it is not only a number game but it is easy to get involved in these competitions!

Even the ARC REF750 surpasses it POWER SUPPLY ENERGY STORAGE: Approximately 1300 joules.

 

[mep]

The Joule race is on...

 

[FrantzM]

The 100V capacitors used in the 1811 and 118 are proprietary designs made exclusively for FM Acoustics.

Manuel Huber points out that the larger a capacitor is, the higher its inductance and resistance at high frequencies. In addition, a capacitor has a nonlinear electrical series resistance (ESR) with respect to frequency. The FM Acoustics capacitors reduce the ESR by a factor of about five as compared to conventional capacitors.
Thus, their ripple current capacity is extremely high. This allows the use of smaller and fewer capacitors, making the ESR lower and far more linear over the entire frequency band.

The 1811 and 118 use a special Mil-spec leaf transformer which can deliver 3 KVA continuous (peak up to 10 KVA), proprietary capacitors, and matched pairs of power transistors mounted directly onto the cooling fins are part of the reason it can supply an immense output current. However, it is the on-board analog computer which really makes possible of its virtually unlimited output current.

The computer measures peak and continuous output current, output voltage, rail voltage bias, temperature and other parameters 20 times per second and compares this data to optimum values stored internally. If you introduce, for example, a very dynamic signal (but not a short circuit), then the output voltage will on average be very high, while the average current will be reasonable but the peak current will be huge, while the rail voltage remains stable.

So here the output current remains absolutely unlimited, producing as much dynamic current as is required by the load. This, of course. requires huge reserves, and the amplifier will reproduce precisely what is fed to the input, limited only by what the a.c. power can supply.

If a short-circuit situation develops, peak current is high, continuous current is shooting extremely high, and the rail voltage drops (because it collapses with such great amounts of current). At that moment, the amplifier shuts off before the output stage can be damaged.

There is no limiting, compression. or anything similar, the amplifier shuts down, and the front-panel display shows an error message. An other circuit is immediately activated to measure the load impedance 20 times per second. As soon as the short circuit is removed, the amplifier automatically resets and becomes operational.

We'll take all these they are marketing points. I can't take the 600 Amperes. It is just isn't possible at 8 ohms or even 1 Ohm.

 

[LL21]

Yes, it is not only a number game but it is easy to get involved in these competitions!

Even the ARC REF750 surpasses it POWER SUPPLY ENERGY STORAGE: Approximately 1300 joules.

capacitance times V = joules. but how do we know what Volts to use? is there a specific thing like 'maximimum voltage output'?

 

[LL21]

capacitance times V = joules. but how do we know what Volts to use? is there a specific thing like 'maximimum voltage output'?

From Wizard:

View attachment 7921

Mephisto inside - with 8 big blue 100V 56000 uF capacitors from Nippon Chemi-Con.
That gives operation storage of 2240 Joule.

 

[audioforever]

I think this is an interesting thread. It is interesting in my view because there are members of this forum not accepting each and every hyped technical nonsense spread by a manufacturer via a mouthpiece reproducing more or less blindly manufacturer's philosophy and being used also by other manufaturers for the same reason. As long as members of this forum know how to fight such kind of guerilla marketing based on founded expression of opinion it can be even informative and instructional and not only interesting to have such threads.

 

[Dave_A]

I think this is an interesting thread. It is interesting in my view because there are members of this forum not accepting each and every hyped technical nonsense spread by a manufacturer via a mouthpiece reproducing more or less blindly manufacturer's philosophy and being used also by other manufaturers for the same reason. As long as members of this forum know how to fight such kind of guerilla marketing based on founded expression of opinion it can be even informative and instructional and not only interesting to have such threads.

Yes, but this is akin to character assassination. FM is a highly regarded and respected company, and their efforts are being trashed left and right in this thread. Probably there's an agenda here.

I doubt FMs sales will affected by these tirades, however.

Cut this wizard guy some slack, he's just passionate about this brand, and rightfully so. The stuff is excellent, imo.

To rockitman: We get it, you don't like FM. There are those that don't like Pass Labs, which is what you use. Personally, I think FM runs rings around Pass Labs. Pass Labs is not the cat's meow either.

I bet you would get all butthurt if someone started an anti-Pass Labs thread. Which is fine actually, audiophiles are sensitive about the brands they own.

Anyway, my 2 cents. Take it or leave it.

 

[rockitman]

To rockitman: We get it, you don't like FM. There are those that don't like Pass Labs, which is what you use. Personally, I think FM runs rings around Pass Labs. Pass Labs is not the cat's meow either.

Anyway, my 2 cents. Take it or leave it.

LOL, you can keep your $100k stamped sheet metal and zip tie construction amps/pre's,ect. I applaud those who have the intestinal fortitude to pad FM's bank account. Cheers !

 

[Dave_A]

LOL, you can keep your $100k stamped sheet metal and zip tie construction amps/pre's,ect. I applaud those who have the intestinal fortitude to pad FM's bank account. Cheers !

And you can keep your Pass Labs with impressive cases and nothing much in them.

 

[rockitman]

And you can keep your Pass Labs with impressive cases and nothing much in them.

wow, declining intelligent quotient. Good day sir...

 

[mep]

I bet you would get all butthurt if someone started an anti-Pass Labs thread. Which is fine actually, audiophiles are sensitive about the brands they own.

Anyway, my 2 cents. Take it or leave it.

I would probably leave the "butthurt" behind me as it sounds too painful. I've been heartbroken before, but never "butthurt."

 

[Dave_A]

fyi: http://www.urbandictionary.com/define.php?term=ButtHurt

 

[garylkoh]

Dave_A - you are not helping things supporting FM Acoustics with posts like this. I too love the FM Acoustics products - I had 255, 266, 122, 611X.

But the members here are all "show me". They haven't heard the FM products because they are not easily available in the US. So, everything they haven't heard, they will question...... and this is NOT a FM trashing thread. If FMA was better represented in the US with shows, etc. it would get a different reception. However, since FMA does not allow reviews of their products, the skepticism is to be expected. I had to stop demo-ing with FMA because at shows, the audience began to question what my products would sound like with gear that they had heard.

 

[rockitman]

I'm sure FM sounds great. Whether the value is there compared to the competition is another matter entirely.

 

[Dave_A]

Dave_A - you are not helping things supporting FM Acoustics with posts like this. I too love the FM Acoustics products - I had 255, 266, 122, 611X.

But the members here are all "show me". They haven't heard the FM products because they are not easily available in the US. So, everything they haven't heard, they will question...... and this is NOT a FM trashing thread. If FMA was better represented in the US with shows, etc. it would get a different reception. However, since FMA does not allow reviews of their products, the skepticism is to be expected. I had to stop demo-ing with FMA because at shows, the audience began to question what my products would sound like with gear that they had heard.

My apologies. That's great. Those are all great units. Well true, not easily, you would have to go to Colorado and visit Audio Limits, the US and Canadian dist. That is the only place at the moment.

 

[Dave_A]

I'm sure FM sounds great. Whether the value is there compared to the competition is another matter entirely.

It does. FM has some of the best resale value. This is truth.

 

[NorthStar]

-- Dave, are you Canadian? ...You speak French?

 

[Dave_A]

-- Dave, are you Canadian? ...You speak French?

No, sorry. I'm in L.A.