How much capacitance does your amp have per watt?

nadams · October 2010

Thought this might be interesting to some of the geeky types.

At your rated WPC, how much capacitance have the amp designers allowed per watt?

Pioneer A-77x - 100wpc @ 8; 16,400uf per channel (8200x2); 164uf per watt
Onkyo TX-7000 - 90wpc @ 8; 22,000uf per channel (22000x1); 244uf per watt

I don't know if it's a statistic that can say anything about an amp, but I like numbers and was wondering what other amps have...

cnh · October 2010

My Adcom GFA-555 -200 wpc @8 ohms has, a total capacitance of 60,000uf... so I assume that's 30K per channel.

More robust amps have even more. Though the Adcom is no slouch for power.

You can tell it has LARGE caps because it takes over a half a minute to discharge when you turn it off...you'll continue to hear your tunes for quite some time before it finally has no juice left.

I've seen amps with twice the Adcom's figures or 60K per channel? I'm sure there are even beefier amps!

High capacitance is a GOOD thing...but merely one of many variables that contribute to a good design. Check out some of the readings that Brock listed in an a past thread.

cnh

heiney9 · October 2010

Aleph 30 - 30wpc @ 4 or 8 ohms; 60,000uF per channel (120,000uF total) = 4000uF per watt.

Did I do the math correctly?

H9

Edit had the wrong amount of capacitance.

billbillw · October 2010

heiney9 wrote: »

Alpeh 30 - 30wpc @ 4 or 8 ohms; 30,000uF per channel = 2000uF per watt.

Did I do the math correctly?

H9

I think so. Pass always putts huge amounts of filter caps in their designs.

My Pass DIY Pearl Phono stage has a whopping 40,000uF per channel, and its output is less than 1 watt. Not sure how to calculate that out.

I know, apples to oranges comparison.

One of the larges cap banks I've seen would probably be in the Odyssey Stratos Mono blocks. Each mono has 120,000-180,000uF of capacitance depending on the configuration and power output of 180-200 watts/ch. (that would be up to 900uf/watt)

Of course, you have to realize, its not all about amount of capacitance. The size of the transformers and the current capability of the output transistors is also very important in determining the power/transient performance of the amp.

geebolt · October 2010

cnh wrote: »

My Adcom GFA-555 -200 wpc @8 ohms has, a total capacitance of 60,000uf... so I assume that's 30K per channel.

More robust amps have even more. Though the Adcom is no slouch for power.

You can tell it has LARGE caps because it takes over a half a minute to discharge when you turn it off...you'll continue to hear your tunes for quite some time before it finally has no juice left.

I've seen amps with twice the Adcom's figures or 60K per channel? I'm sure there are even beefier amps!

High capacitance is a GOOD thing...but merely one of many variables that contribute to a good design. Check out some of the readings that Brock listed in an a past thread.

cnh

60,000 divided by 200 equals 300uf not 30k. (If I'm figuring right).
Same specs for my Emotiva XPA-5.

George

heiney9 · October 2010

Bill I had the wrong figure's the Aleph is 60K uF per channel for a total of 120K uF. Each channel uses (6) 10K caps.

heiney9 · October 2010

billbillw wrote: »

One of the larges cap banks I've seen would probably be in the Odyssey Stratos Mono blocks. Each mono has 120,000-180,000uF of capacitance depending on the configuration and power output of 180-200 watts/ch. (that would be up to 900uf/watt)

Of course, you have to realize, its not all about amount of capacitance. The size of the transformers and the current capability of the output transistors is also very important in determining the power/transient performance of the amp.

The Aleph 60's I'm looking at (mono's) have 120,000 per mono for 60wpc performance.

I agree 100% with your second point. A great designer will match all 3 parameters for great performance together.

megasat16 · October 2010

Guyz....figuring out capacitance is not just the measure of power. In order to check the true storage of the energy (joule) on these capacitor banks, you need to figure out the voltage of the capacitors or the power supply rails voltage.

Just quoting the capacitance value does not mean a more powerful amp. You can have 1farad 12V or you can have 0.1farad at 1000V. Guess you know what you want now!

xj4094dg · October 2010

Continuous Power Output - Stereo
220 watts RMS x 2, 20Hz-20kHz, 8W
385 watts RMS x 2, 20Hz-20kHz, 4W
385 watts RMS x 2, 20Hz-20kHz, 2W
Continuous Power Output - Mono
750 watts RMS, 20Hz-201kHz, 8W
1000 watts RMS, 20Hz-20kHz, 4W
Current Capacity
50 amperes continuous
90 amperes peak
AC Power Requirements: 1000 watts
100,000uF computer-grade capacitors in power supply

cnh · October 2010

megasat16 wrote: »

Guyz....figuring out capacitance is not just the measure of power. In order to check the true storage of the energy (joule) on these capacitor banks, you need to figure out the voltage of the capacitors or the power supply rails voltage.

Just quoting the capacitance value does not mean a more powerful amp. You can have 1farad 12V or you can have 0.1farad at 1000V. Guess you know what you want now!

Point well-taken. But I don't think most posts above really disagree with that. As I read them they say that capacitance is only one factor that needs to be taken into consideration.

Thanks for elaborating on the others.

cnh

megasat16 · October 2010

Yes and No cnh! No post above mention otherwise. I am just filling in.

I think it's not as simple as to equate the amps power per watt with the capacitance value. The capacitor banks as energy storage will have enough power reserve for the short term peak power for a brief duration. That's why people generally says the more capacitance means more power in general since it has more reserve for the peak power.

heiney9 · October 2010

megasat16 wrote: »

Guyz....figuring out capacitance is not just the measure of power. In order to check the true storage of the energy (joule) on these capacitor banks, you need to figure out the voltage of the capacitors or the power supply rails voltage.

Just quoting the capacitance value does not mean a more powerful amp. You can have 1farad 12V or you can have 0.1farad at 1000V. Guess you know what you want now!

Mega, just giving him the geeky answer he asked for, nothing more nothing less.

H9

heiney9 · October 2010

megasat16 wrote: »

Yes and No cnh! No post above mention otherwise. I am just filling in.

I think it's not as simple as to equate the amps power per watt with the capacitance value. The capacitor banks as energy storage will have enough power reserve for the short term peak power for a brief duration. That's why people generally says the more capacitance means more power in general since it has more reserve for the peak power.

Nor should one think that watts or peak amperes or whatever is on the spec sheet means a damn thing in and of itself.

heiney9 · October 2010

megasat16 wrote: »

Yes and No cnh! No post above mention otherwise. I am just filling in.

I think it's not as simple as to equate the amps power per watt with the capacitance value. The capacitor banks as energy storage will have enough power reserve for the short term peak power for a brief duration. That's why people generally says the more capacitance means more power in general since it has more reserve for the peak power.

What do you mean by "power"? extra capacitance doesn't increase wattage, as you know. So for those that think 200wpc is "better" than 40wpc when you say "power" in this instance of capacitor charging/discharging you are not talking watts.

H9

megasat16 · October 2010

Ok for Geeky answer?

The amp with 200W/ch that has 10000uF@100V per channel will have more dynamic watts (power) than another amp with 200W/ch that has 10000uF@63V.

That's why I am saying quoting capacitance along with power output is inaccurate.

I guess it should make sense what I was trying to say before?

FTGV · October 2010

Class of operation plays a part.ie. because of it's high and constant current draw even at idle, a Class A amplifier will benifit most from large storage capacitance.

megasat16 · October 2010

heiney9 wrote: »

What do you mean by "power"? extra capacitance doesn't increase wattage, as you know.

H9

H9...you are making it harder than it should have been.

Extra Capacitance simply means it can store more energy. But how much more energy depends on what voltage it's storing at.

So for those that think 200wpc is "better" than 40wpc when you say "power" in this instance of capacitor charging/discharging you are not talking watts.

What do you mean?

megasat16 · October 2010

FTGV wrote: »

Class of operation plays a part.ie. because of it's high and constant current draw even at idle, a Class A amplifier will benifit most from large storage capacitance.

Very True! In some class amplifiers, you don't need a lot of capacitance at all.

I guess it's getting complicated trying to comprehend things in lamer terms.

heiney9 · October 2010

megasat16 wrote: »

H9...you are making it harder than it should have been.

Extra Capacitance simply means it can store more energy. But how much more energy depends on what voltage it's storing at.

What do you mean?

You missed my point entirely. Just trying to get you to clarify for those less learned. I understand it completely.

I guess my point was missed on the caps charge/discharge comment. So nevermind.

H9

hoosier21 · October 2010

my head hurts just reading this thread

dorokusai · October 2010

nadams wrote: »

At your rated WPC, how much capacitance have the amp designers allowed per watt?

More than enough to drive every loudspeaker I've ever owned....and others' as well. Simple.

I agree with some later comments as it's not just about that single figure. There are other smaller/larger figures, some of which may seem totally meaningless or swing greatly between designs, that also determine how good your amplifier is.

cristo · October 2010

Fender Pro Reverb (silverface ~ 1976) 95 uf (the first two 70's are in series so they
count as 35 uf - that's for the power tubes, then 20 more for the driver, 20 more for
the 2nd stage tubes and 20 more for the 1st stage). 45 watts, so 2.11 uf/watt
but the B+ is 360 - 440 volts depending on the stage of amplification.

megasat16 · October 2010

heiney9 wrote: »

You missed my point entirely. Just trying to get you to clarify for those less learned. I understand it completely.

I guess my point was missed on the caps charge/discharge comment. So nevermind.

H9

Ok Brock, I guess I missed what you wanted to say. I shall try to simplify but it's a long shot at best.

Capacitor banks and sizing depends on the amplifier designs (headroom) and Class.

We simply can't say the size of the capacitor banks or capacitance to easily equate with watts. Capacitors banks are like water tanks. They can be tall or short (voltage) and fat or slender (capacitance). The ones that can store more energy is the tall and fat one (high voltage and high capacitance).

So, how does energy storage in Joule relates to the Watts (power)?

The energy storage there can be related back into Power based on the load resistance (reactance of speakers).

I think we can get into that who really interested in it?

[Deleted User] · October 2010

Hello,
It is C=CV, where C (charge in coulombs) equals the capacitance times the operating voltage. A power supply for a vacuum tube circuit is usually much higher in operating voltage than one used in a solid state circuit. The power supply needs to have a sufficient charge to not sag when the peak demand happens. Also, it needs to have a low source impedance and sometimes increasing the capacitance raises the impedance. Like most things audio, it is a question of balancing one factor against another for the best results.
Cheers, Ken

megasat16 · October 2010

Thanks Ken, It's a better explanation than I could think of.

nadams · October 2010

I do see the points of everyone who posted in this thread... I just figured it'd be fun to compare amps with a somewhat arbitrary figure. What I should've detailed is the type of amplifier, and the voltage of the caps. However, pretty much all the ones I've seen have been in the 65vdc range.

And the point of "today's watts aren't like yesterday's watts" is pretty much what I was trying to convey. You can have a "200wpc" receiver today that doesn't have nearly the cap backing that a 70 or 90wpc receiver did 30 years ago.

Outfitter03 · October 2010

How about 32 megajoules. Now that is a capacitor bank.

http://www.popularmechanics.com/technology/military/4231461

megasat16 · October 2010

Uh no...You can't handle 32 of me!

FTGV · October 2010

If space is at a premium and no room for those large caps (and transformer) then using one these is an option.http://www.toutlehautparleur.com/images/Hypex_UcD/UCD400MPE/Hypex_SMPS400.pdf Since their filtering 100khz and not 120hz the capacitance requirements are substantially reduced.

lanchile · October 2010

nadams wrote: »

Thought this might be interesting to some of the geeky types.

At your rated WPC, how much capacitance have the amp designers allowed per watt?

Pioneer A-77x - 100wpc @ 8; 16,400uf per channel (8200x2); 164uf per watt
Onkyo TX-7000 - 90wpc @ 8; 22,000uf per channel (22000x1); 244uf per watt

I don't know if it's a statistic that can say anything about an amp, but I like numbers and was wondering what other amps have...

Well, I have build many diy amps. and it is not only how much capacitance your amp is using. it is how low ESR is in those caps. it is better to use small caps like: 3x6,800uf than 1x20,000uf you know those big caps like coke cans lol. usually the small caps are faster and they have low ESR than those big coke cans caps also the quality in the caps is important too. The capacitance it is the reserve of power in an amp. that means if you have enough capacitance in your amp, it will not run out of juice. More capacitance it does NOT mean...more power!!!! I hope I made my self clear.

and lets see here, if a circuit has a 30vdc and you use a 50vdc cap that is good!!!, but if you want to use an 80vdc cap instead of the 50vdc cap that does not mean it will give you more power, it will only handle more voltage (30vdc more) same thing with those 85* and those at 105* that it just for the temperature only.

all My 100 watts RMS amps That I build I use Mundorf caps total 20,000uf per channel. and never go for the usual thing like if an amp has 120,000uf per channel at 100watts RMS will be better than one using just 20,000uf per channel. all is in the design and the quality.;)

Fongolio · October 2010

Speaking in very general terms, and primarily solid state, doesn't large capacitance more or less equal larger dynamic headroom?

How much capacitance does your amp have per watt?

Comments