Trying to understand output capability of XPA Gen3

[KeithL]

There are a few things here that really need a bit of clarification...

First of all... the actual efficiency of loudspeakers varies A LOT... from as low as 82 dB to as high as 104 dB (per 1 watt in)... 
(So you would need A HUNDRED TIMES as much power with that low-efficiency speaker to play as loud as the most efficient one.)

 Second of all, room acoustics, and speaker frequency response, also vary widely.
A "dead" room will obviously need a lot more power to reach a certain level than a "live" room.

And, although it is somewhat more difficult to quantify, in larger rooms, some speakers "just fill a room better than others".
Things like the directionality and surface area of the drivers, and the location relative to room boundaries, make a difference in "the level you can reach in a room".

But, in this particular case, there is also something you need to understand about amplifier power and music.
Music is very dynamic... so, when you play music, the AVERAGE power is FAR less than the peak power.
A common estimate used in the industry is that the difference can be as large as 10x or 20x.

So... (and this is not based on any specific amplifier of ours)....

Music is quite dynamic... which means that the AVERAGE amount of power it requires is FAR less than the peak power it needs...
A typical "250 watt amplifier" can probably deliver 350 watts or so peak before it clips.
And, when playing typical music, "as loud as it can without clipping", that amplifier is probably being asked to deliver an AVERAGE power of only 35 - 50 watts.
So, when you see someone say that "an amp required a 20 amp service to reach maximum power"....
They're talking about continuous power, on a test bench, with a continuous test signal ...
(Which is not at all representative of the situation when playing music.)
In real life, when playing actual music, and not clipping badly, that amp will NOT need anywhere near that much current.

Aug 16, 2023 1:27:54 GMT -5 leonski said:

Aug 15, 2023 17:07:19 GMT -5 AudioHTIT said:

Ah, active crossover, got it, that’s the way to go! But yes, a speaker with built in amps (like the Emotiva AM5S I use on the desktop) would be referred to as active speakers, and in most cases would have active crossovers, but I suppose they might still be called active even with passive crossover. 🧐

I don’t think I’ve seen an XPA amp with a 20 amp socket (pretty sure neither my XPA-7 G2 or G3 had one), but if so that would indicate it could consume up to 2400W given the right power supply. A 20A socket would have horizontal blades.

I think a 20 amp socket will have one 'T-Shaped' and one blade up/down.......So it's gonna be OK with double paralled blades of a 15 amp AND the 20 amp which is 2 blades at RIGHT ANGLES.....   Ground in either case is the same.
20 amps at 120 v is 2400 watts.....but that is short time period.....And it's the same for 15 amp / 120v which is 1800 watts short term.    I think the DERATE long time period would be 20%?     If curious, talk to an electrician.    All sorts of rules apply.....
I don't know that 'peak power' to a speaker would be a problem......But I'd get clear on just WHAT was required to get to maximum power on the amplifier.....If it has a 20 amp setup?   Make sure the power cord is 12ga or 10ga.   And that EMO didn't 'cut corners' by
supplying a 14ga cord.      

At least one of the early XP  mono amps required a 20 amp service to reach maximum power.    All those poor schleps who put a pair of 'em on a single 15 amp service along with the rest of the HT system were wasting money.....But didn't seem to care.    I had LOTS
of discussions with people pointing out that their 600 a side amps would NEVER get that power wired the way which was very common....

The IEC connector .....on chassis.....is as AUDIO indicates......

[AudioHTIT]

Aug 17, 2023 10:51:25 GMT -5 KeithL said:

There are a few things here that really need a bit of clarification...

First of all... the actual efficiency of loudspeakers varies A LOT... from as low as 82 dB to as high as 104 dB (per 1 watt in)... 
(So you would need A HUNDRED TIMES as much power with that low-efficiency speaker to play as loud as the most efficient one.)

 Second of all, room acoustics, and speaker frequency response, also vary widely.
A "dead" room will obviously need a lot more power to reach a certain level than a "live" room.

And, although it is somewhat more difficult to quantify, in larger rooms, some speakers "just fill a room better than others".
Things like the directionality and surface area of the drivers, and the location relative to room boundaries, make a difference in "the level you can reach in a room".

But, in this particular case, there is also something you need to understand about amplifier power and music.
Music is very dynamic... so, when you play music, the AVERAGE power is FAR less than the peak power.
A common estimate used in the industry is that the difference can be as large as 10x or 20x.

So... (and this is not based on any specific amplifier of ours)....

Music is quite dynamic... which means that the AVERAGE amount of power it requires is FAR less than the peak power it needs...
A typical "250 watt amplifier" can probably deliver 350 watts or so peak before it clips.
And, when playing typical music, "as loud as it can without clipping", that amplifier is probably being asked to deliver an AVERAGE power of only 35 - 50 watts.
So, when you see someone say that "an amp required a 20 amp service to reach maximum power"....
They're talking about continuous power, on a test bench, with a continuous test signal ...
(Which is not at all representative of the situation when playing music.)
In real life, when playing actual music, and not clipping badly, that amp will NOT need anywhere near that much current.

Aug 16, 2023 1:27:54 GMT -5 leonski said:

I think a 20 amp socket will have one 'T-Shaped' and one blade up/down.......So it's gonna be OK with double paralled blades of a 15 amp AND the 20 amp which is 2 blades at RIGHT ANGLES.....   Ground in either case is the same.
20 amps at 120 v is 2400 watts.....but that is short time period.....And it's the same for 15 amp / 120v which is 1800 watts short term.    I think the DERATE long time period would be 20%?     If curious, talk to an electrician.    All sorts of rules apply.....
I don't know that 'peak power' to a speaker would be a problem......But I'd get clear on just WHAT was required to get to maximum power on the amplifier.....If it has a 20 amp setup?   Make sure the power cord is 12ga or 10ga.   And that EMO didn't 'cut corners' by
supplying a 14ga cord.      

At least one of the early XP  mono amps required a 20 amp service to reach maximum power.    All those poor schleps who put a pair of 'em on a single 15 amp service along with the rest of the HT system were wasting money.....But didn't seem to care.    I had LOTS
of discussions with people pointing out that their 600 a side amps would NEVER get that power wired the way which was very common....

The IEC connector .....on chassis.....is as AUDIO indicates......

I think most of us understand that (and I agree a 20A service isn’t always required for a ‘20A amp’). What about the 20A label above the 15A chassis socket?

[KeithL]

I'm going to give you the official story here...

The AMPLIFIER ITSELF is safety certified to consume 20 amps.
The actual IEC socket we use is certified to have "a 15 amp continuous rating".

I'm going to go off on a bit of an editorial tangent here...
A few folks have noticed in the past that certain of our amps seem to to have confusing power consumption ratings.
(For example a few of our models appear to be rated to deliver more power than their "maximum power consumption" under certain conditions.)
The bottom line there is that, in order to receive various safety certifications, the amplifier must be tested in certain very specific ways.
And, once we receive those certifications, we are required to state those numbers "exactly as they are provided to us by the certifying lab".
And that "maximum power consumption" is one such number.
(This is true even if, as is sometimes the case, the amp may be capable of delivering more power with a different load.)

Aug 17, 2023 11:16:53 GMT -5 AudioHTIT said:

Aug 17, 2023 10:51:25 GMT -5 KeithL said:

................................

I think most of us understand that. What about the 20A label above the 15A chassis socket?

[leonski]

I had this discussion before. But my point was that someone purchasing a pair of 20 amp (required for max power) Mega-Monos will not get anywhere near that when running the pair of 'em on a 15amp service with the rest of the stuff tossed in for good measure.
My OPINION has always been that if you like a pair of speakers equally?   By the more sensitive pair and save by buying better amplifiers of lesser power......In an extreme case, one of the 30-a-side class 'A' amps from Pass Labs.....

Sure....the PS caps will be 'charged' to maximum voltage. So you have a brief amount of time for a burst of dynamic power. If you are in the least curious? 1000mfd at 80 volts is only 3.2 joules.......not much at all.

www.omnicalculator.com/physics/capacitor-energy

If you decide to 'play' with this calculator?    Try a very high voltage....say 400 volts....which might be typical of a TUBE amp and watch the stored energy jump UP.   this is why tube amps have a certain.....advantage over SS.    And lack what most SS guys think is 
needed in the form of some huge capacitor bank......Simply not needed in tube gear.....


It would also not surprise me to learn that 'testing labs' use a Variac to stabilize power line voltage TO the amp. Something few people would ever attempt.....About the most I've seen is someone running thicker wire TO the outlets in question from a dedicated circuit in order
to minimize voltage drop....
I ran a lab-standare X-Ray machine which had such circuitry built in. I think Monster made a device for home use which provided a stable voltage output.......

Forget all that nonsense about how speakers load a room and such. Just smoke. You are really up against the basic sensitivity OF such speaker VS power available. And don't forget that driving speakers nearer (not at, necessarily) limits will also change them.
Copper resistivity increases as it warms. Same for Aluminum which I understand can be used in voice coils.....it weighs less. You'll see this Phenom on LONG distance very high power electric distribution lines which are 'derated' in warm summers.....I've see pics of these
lines in cold weather V hot and the line is longer in the heat......sagging......

We can talk about an amps capability into a resistor V a real speaker some other time. But the bottom line is some amps simply do not do well into a real load as impdance drops or reactance increases .....or BOTH.....

[fredygump]

Aug 17, 2023 6:54:04 GMT -5 405x5 said:

Aug 14, 2023 20:36:57 GMT -5 fredygump said:

Why no make and model of the speaker you’re using sure as heck that would answer a lot of questions

The make is by me, and the model is #1.  I thought it was  clear this is DIY. 

[SteveH]

Aug 17, 2023 16:36:29 GMT -5 leonski said:

I had this discussion before. But my point was that someone purchasing a pair of 20 amp (required for max power) Mega-Monos will not get anywhere near that when running the pair of 'em on a 15amp service with the rest of the stuff tossed in for good measure.

You are absolutely correct leonski. My previous Carver system would make the family room lights dim with the bass and occasionally trip the 15 amp breaker in the service entrance panel. I knew there was no way I could power two DR1s, a Thirteen 1-6S, two S10 subs, an RMC-1 and the rest of my goodies on my family room's single 15 amp circuit. I love to listen to music at an elevated level with consideration for my neighbors. Both my neighbors listen to my genres and I told both of them to let me know if the music is too loud before calling the cops. I have never had a complaint (yet).

[fredygump]

Aug 17, 2023 13:06:56 GMT -5 KeithL said:

I'm going to give you the official story here...

The AMPLIFIER ITSELF is safety certified to consume 20 amps.
The actual IEC socket we use is certified to have "a 15 amp continuous rating".

I'm going to go off on a bit of an editorial tangent here...
A few folks have noticed in the past that certain of our amps seem to to have confusing power consumption ratings.
(For example a few of our models appear to be rated to deliver more power than their "maximum power consumption" under certain conditions.)
The bottom line there is that, in order to receive various safety certifications, the amplifier must be tested in certain very specific ways.
And, once we receive those certifications, we are required to state those numbers "exactly as they are provided to us by the certifying lab".
And that "maximum power consumption" is one such number.
(This is true even if, as is sometimes the case, the amp may be capable of delivering more power with a different load.)

Can you comment on the question about peak watts with multiple channels driven? 

At the beginning of this thread I listed theoretical max current requirements based on a combination of speaker modeling and actual measurements.  Is it possible to say if a theoretical demand of ~1800 peak watts split between 8 channels is possible?  From what I can figure out, it seems like it'll be fine.

Plenty of guys are going to say that the subwoofers built into my speakers can't give good bass, because I don't have a 3,000watt amp for each driver.  I think that is total BS, because I know the specs of my sub drivers. But I would like to be able to say that not only do I have enough power, but I have "x" number of watts headroom.

I'm not saying I'll ever use all the power, but from a design/ engineering point of view, I want to understand the limits of my system.

[405x5]

Aug 17, 2023 19:14:49 GMT -5 fredygump said:

Aug 17, 2023 6:54:04 GMT -5 405x5 said:

Why no make and model of the speaker you’re using sure as heck that would answer a lot of questions

The make is by me, and the model is #1.  I thought it was  clear this is DIY. 

The understanding of what you’re doing is quite clear, except for the fact that these are homemade loudspeakers of your design. That’s great and I commend you for it.

[leonski]

Aug 17, 2023 19:31:55 GMT -5 SteveH said:

Aug 17, 2023 16:36:29 GMT -5 leonski said:

I had this discussion before. But my point was that someone purchasing a pair of 20 amp (required for max power) Mega-Monos will not get anywhere near that when running the pair of 'em on a 15amp service with the rest of the stuff tossed in for good measure.

You are absolutely correct leonski. My previous Carver system would make the family room lights dim with the bass and occasionally trip the 15 amp breaker in the service entrance panel. I knew there was no way I could power two DR1s, a Thirteen 1-6S, two S10 subs, an RMC-1 and the rest of my goodies on my family room's single 15 amp circuit. I love to listen to music at an elevated level with consideration for my neighbors. Both my neighbors listen to my genres and I told both of them to let me know if the music is too loud before calling the cops. I have never had a complaint (yet).

View Attachment

SAME ISSUE.
My Carver Cube....the M400t would 'dim' the lights in the house IN TIME to the music.....and the amp had a 15 amp fuse!    
The speaker at that time was the Magnepan MG1, which I think was rated at 5 ohms.....The Ladder Display on the amp would be flashing except for the TOP lamp.....

If they neighbors have never complained, you are NOT trying hard enough.....

[leonski]

Carver was a real Power Supply Innovator. His 'Carver' line.......used some kind of Tracking / Railed power supply which basically turned ON and OFF in 'time' to the music.....Partly what we'd call class 'H' or maybe class 'G'.....I never DID get that straight.
And partly a giant choke (for the magnetic field.....hint hint) with a TRIAC I'm told. My amp emitted a very low-level 'putt-putt' noise. The collapse of the magnetic field supplied a 'kick' which was turned into power for the amp.......
My amp ran cool almost no matter what. Even full-tilt into my panels? Barely warm. But I fixed even THAT with a fan I fabricated which fit on the BACK of the amp and drew air thru......

www.diyaudio.com/community/threads/carver-magnetic-field-power-amp-whazzit.69614/

A mix of information courtesy of DIY Audio.......I think it was a CHOKE, not a transformer.....but I've also never seen a schematic....

[leonski]

Aug 17, 2023 20:02:56 GMT -5 fredygump said:

Aug 17, 2023 13:06:56 GMT -5 KeithL said:

I'm going to give you the official story here...

The AMPLIFIER ITSELF is safety certified to consume 20 amps.
The actual IEC socket we use is certified to have "a 15 amp continuous rating".

I'm going to go off on a bit of an editorial tangent here...
A few folks have noticed in the past that certain of our amps seem to to have confusing power consumption ratings.
(For example a few of our models appear to be rated to deliver more power than their "maximum power consumption" under certain conditions.)
The bottom line there is that, in order to receive various safety certifications, the amplifier must be tested in certain very specific ways.
And, once we receive those certifications, we are required to state those numbers "exactly as they are provided to us by the certifying lab".
And that "maximum power consumption" is one such number.
(This is true even if, as is sometimes the case, the amp may be capable of delivering more power with a different load.)

Can you comment on the question about peak watts with multiple channels driven? 

At the beginning of this thread I listed theoretical max current requirements based on a combination of speaker modeling and actual measurements.  Is it possible to say if a theoretical demand of ~1800 peak watts split between 8 channels is possible?  From what I can figure out, it seems like it'll be fine.

Plenty of guys are going to say that the subwoofers built into my speakers can't give good bass, because I don't have a 3,000watt amp for each driver.  I think that is total BS, because I know the specs of my sub drivers. But I would like to be able to say that not only do I have enough power, but I have "x" number of watts headroom.

I'm not saying I'll ever use all the power, but from a design/ engineering point of view, I want to understand the limits of my system.

One other 'possible' here, Freddy?

An amp with say.....5 channels, a not uncommon configuration these days, can  be setup one of 2 major ways.

EACH channel has its OWN power supply.   So that channel will be rated in some fashion and maybe the amp will have ratings for single channel driven, stereo and even 'all' channels driven......
Each channel has AC from the power input....and are all paralleled and each amp has 120vac INPUT and draws current proportional to its needs......Each module is essentially independent.
Each module may even have its OWN fuse or breaker.    A shorted speaker cable will not destroy the entire amp.....or at least that is the plan.....

The OTHER major setup would be what it appears EMO is up to.    ONE giant power supply which shares power among however many channels the amp has......the power 'bus' is something that 
each 'module' plugs into and is NOT power from the wall, but power from the Power Supply.....60vdc or 80vdc or whatever the voltage may be.....even 'rails' of G or H......which are not output classes....
So in the case of EMO, you have some giant power supply which for say......stereo is maybe 2x or 3x maximum anticipated need.   Maybe even a bit more?     Engineering standards enter into this.
So when playing more channels....the PS capacity is divided up with extra available for peaks from all channels.      Low demand from one or more channels just 'frees' up more available for OTHERS.

Take your pick.