[I.Greyhound Fan]

subjective tests are not good to show up distortion(inaudible),you can do thd measurements,however what
Pneumonic said was inaudible distortion,there is no sonic difference in that case.

Exactly, that is my point.

[DaveC113]

What sonic difference exists between a low powered amp that "performs" with inaudible levels of distortion and a high powered amp that does the same?

I can say it's very difficult to tell the difference between my 5 wpc SET and my 375 wpc Crown XLS class D amp until the volume gets loud. But it's really dependent on the speakers, my SET won't do a good job with speakers that use drivers with heavy cones because it doesn't have the damping factor but on my speakers the cones are 2g and they sound pretty much identical.

[I.Greyhound Fan]

I can say it's very difficult to tell the difference between my 5 wpc SET and my 375 wpc Crown XLS class D amp until the volume gets loud. But it's really dependent on the speakers, my SET won't do a good job with speakers that use drivers with heavy cones because it doesn't have the damping factor but on my speakers the cones are 2g and they sound pretty much identical.

And that brings us back to system matching and synergy.  A low watt amp is not going to do well with a low sensitivity speaker and speakers that thrive on high current like my Maggies

[Early B.]

The answer to the original question on how much power you really need is -- ALOT. Here's why:  generally speaking, you can recognize the deficiencies from an underpowered system, but have you ever heard an audiophile complain that his massive amp sounds too powerful?

After trading out a bunch of amps over the years, I came to the conclusion that 250 wpc into 8 ohms is the minimum I would consider. My amp snickers like a tickled two-year old at the light load I'm asking it to carry. I'm not suggesting that lower powered amps generally sound inferior by any means, but I'm saying that to be on the safe side, I want more available power than I'll likely ever need.

[I.Greyhound Fan]

Low powered amps can certainly limit your options for speakers.  I got to hear a pair of Martin Logan CLX's with a pair of Mac 601 monoblocks that put out ?600wpc yesterday at my local Magnolia Best Buy store.  It sounded awesome.  You could drive them with 20wpc but not to the dynamics and level that I heard them.

[Tyson]

I wish I was that handy.  I can use a soldering iron but I am not very adept when it comes to following schematics for electronic gear from scratch.

Besides, where do you get the kit or plans?

Output boards:

http://www.diyaudio.com/store/amplifier-circuit-boards/power-amplifiers/first-watt-clones.html

Power Supply boards:

http://www.diyaudio.com/store/amplifier-circuit-boards/power-supplies-accessories/universal-amplifier-power-supply-v3.html

Pre-drilled Chassis:

http://www.diyaudio.com/store/amplifier-chassis/full-width-40mm-heatsinks/deluxe-amplifier-chassis-enclosure-4u-216.html

[I.Greyhound Fan]

Output boards:

http://www.diyaudio.com/store/amplifier-circuit-boards/power-amplifiers/first-watt-clones.html

Power Supply boards:

http://www.diyaudio.com/store/amplifier-circuit-boards/power-supplies-accessories/universal-amplifier-power-supply-v3.html

Pre-drilled Chassis:

http://www.diyaudio.com/store/amplifier-chassis/full-width-40mm-heatsinks/deluxe-amplifier-chassis-enclosure-4u-216.html

Cool, what about all the electronics, power transformer, schematics, ect.?

You have peaked my interest.

[Alan]

Cool, what about all the electronics, power transformer, schematics, ect.?

You have peaked my interest.

Electronics - Mouser or Digi-Key, sometimes you can find someone selling kits (I was lucky last time).

Transistors must be matched, there's a couple guys who sell those.

Antek are probably the best value in transformers, or Avel Lindberg.

Schematics are available, but not really needed to stuff the boards.

Look for the build guides, the author is very helpful. (and local to me).

The Amp Camp amp is a very simple build and sounds great. Only 5 watts, but it might drive your bedroom system fine. I'm currently working on an Aleph J.

Have fun with it.

[BobM]

Here's my philosophy ...

(1) the most important component is the room
(2) the speakers have to fit the room
(3) the amp has to fit the speakers

That certainly leaves a lot of room (pardon the pun) to wriggle about with high or low sensitivity speakers, cones, horns, panels and the like. So if you have horns or high sensitivity speakers you are in the wonderful position to be considering a SET amp. But if you have inefficient panels then high powered solid state might make the most sense, but then you can put tubes in front of it and still be happy.

[RDavidson]

The answer to the original question on how much power you really need is -- ALOT. Here's why:  generally speaking, you can recognize the deficiencies from an underpowered system, but have you ever heard an audiophile complain that his massive amp sounds too powerful?

After trading out a bunch of amps over the years, I came to the conclusion that 250 wpc into 8 ohms is the minimum I would consider. My amp snickers like a tickled two-year old at the light load I'm asking it to carry. I'm not suggesting that lower powered amps generally sound inferior by any means, but I'm saying that to be on the safe side, I want more available power than I'll likely ever need.

That makes sense, definitely. Set it and forget it. But personally, I have yet to hear an "affordable" big amp (250 wpc +) that sounds just as good pushing 1/4 watt as it does at about 1/4-1/2 of it's total output. I find that most amps have a sweet spot where they're having to work a little bit to sound their best, but they aren't anywhere near their limit. That's where speaker / amp matching is really key. If you're running a 5 watt SET amp, but rarely even push it to 1 watt, you're pretty much always in its sweet spot. Same goes for a 250 wpc amp. If you're only tapping into maybe 50-100 wpc continuously, then you're running it in the sweet spot. That's just my experience. Only the upper echelon of high powered amps seem to have the refinement to push 1/4 of a watt just as well as they push 1/4-1/2 of their total output.......and that's why they're flippin' expensive. Set it and forget it indeed.

[BobM]

Even with a 250 watt amp, I bet it's mostly running 1-2 watts continuous, maybe even less, and only going over that on big crescendo's and bass thumps. Of course if you're playing house music then those bass thumps are rather continuous.

[RDavidson]

Even with a 250 watt amp, I bet it's mostly running 1-2 watts continuous, maybe even less, and only going over that on big crescendo's and bass thumps. Of course if you're playing house music then those bass thumps are rather continuous.

Entirely depends on other factors already discussed (speakers, room size, listening distance, listening level, music dynamic range). But yeah, I think there are probably just as many cases where people don't realize they're using 10 wpc or less 90% of the time as there are cases where people don't realize they're using 100 wpc or more 90% of the time. Speaker and amp matching is more critical than a lot of people realize, particularly when taking into consideration the amplifier's "sweet spot".....ie where you want to be pretty much all the of the time.

[Freo-1]

The point I was trying to make is that this thread is off....power and spl is in log terms, not linear.  Thus 2,4, 8, 15, 32, 64 is linear not normal terms. 

What one needs for transiet power, i.e. <1% of the time and what one needs from an amp isn't max power.   Tube amps tend to compress, SS amps tend to clip (nasty sound).

+1   




I think this point is being missed in this thread. 

[I.Greyhound Fan]

Electronics - Mouser or Digi-Key, sometimes you can find someone selling kits (I was lucky last time).

Transistors must be matched, there's a couple guys who sell those.

Antek are probably the best value in transformers, or Avel Lindberg.

Schematics are available, but not really needed to stuff the boards.

Look for the build guides, the author is very helpful. (and local to me).

The Amp Camp amp is a very simple build and sounds great. Only 5 watts, but it might drive your bedroom system fine. I'm currently working on an Aleph J.

Have fun with it.

 
Thanks Alan.  I would like to build and F5 Turbo.  My system in my Master bedroom consists of a pair of Monitor Audio S1's, 6 ohm and a sensitivity of about 88 or 89 dB.   My room size is 17x17 with a cathedral ceiling.   

I can solder but I am not trained in reading electronic schematics.

[werd]

Big power basically translate into higher output rating in watts for A/B or more unswtiched dynamic power in Class A. What powers the output devices are capacitors.  What keeps the capacitors stiff is the transformer VA size. The reason why you want a big VA size transformer is because the amp sees the local neighbourhood transformer through the house plug, wiring, fuse Box, and hopefully not any other Junction boxes. This all translates into high house impedance. Which screws with your dynamics. Big transformers keep a reservoir of power to keep those output capacitors stiff. Which allows for transient power to your speakers. Big power is a bandaid fix for a 15 amp circuit.  Aside  from the obvious huge speakers that will only work with big amps.

Good work around is to plug your amp into a suitable transformer conditioner.

[S Clark]

Although it isn't discussed much, with speakers with lots of drivers, back EMF can be a factor in controlling the speaker.  Although my GR-Research LS9's are rather efficient, they need a couple of hundred watts/channel  to maximize what the do well, dynamics.

[Folsom]

 

Werd, there's ten things going on for every one you've said.

Bigger amps with larger reservoirs and higher headroom suffer less from the power problems that represent power that does not exist. Essentially the amp acts sort of like a PFC in a manner by being above and beyond the duty of needing anything near. However all the impedance etc aren't a loss of power so much as they're interfering, and usually with noise.

Large VA transformers are good for in-rush current, and very useful for when it'll cost you an exorbitant amount of space and money to populate with enough capacitance to make up for needing the efficiency of a very large transformer. It can be done easily with small devices, very large capacitor reservoirs for their size to the point where you turn it off and the device plays full volume for a few seconds. You can't do that with a Pass amp. You probably can't afford too...

The size retains thermal efficiency, particularly at 60hz, and not necessarily a relation to the amperes needed.

This is all about power delivery, not the amount. 15a is more than enough to service any Pass amp WITH EASE. But we're talking about an amplifier that has a constant current power supply so it's always using power, and sometimes more. under load the capacitors actually get a work out, so the efficiency of in-rush current means a lot. The inrush current isn't necessarily high, but it's happening a lot. It'd be wise to beef the capacitance but we're talking soft starts and CH-CHING! At least for some better capacitors.

Believe it or not, I'm on the job of a PSU board for the F's... Not the turbo though, totally unruly in size. Perhaps I'll quarter up the pieces but it destroys the benefits quiet a bit.

[Folsom]

Although it isn't discussed much, with speakers with lots of drivers, back EMF can be a factor in controlling the speaker.  Although my GR-Research LS9's are rather efficient, they need a couple of hundred watts/channel  to maximize what the do well, dynamics.

What happens when you put the TDA7297 on them? I've driven Piega Premium 5.2's to moderate levels without issue. They're not efficient.

[G Georgopoulos]

Big power basically translate into higher output rating in watts for A/B or more unswtiched dynamic power in Class A. What powers the output devices are capacitors.  What keeps the capacitors stiff is the transformer VA size. The reason why you want a big VA size transformer is because the amp sees the local neighbourhood transformer through the house plug, wiring, fuse Box, and hopefully not any other Junction boxes. This all translates into high house impedance. Which screws with your dynamics. Big transformers keep a reservoir of power to keep those output capacitors stiff. Which allows for transient power to your speakers. Big power is a bandaid fix for a 15 amp circuit.  Aside  from the obvious huge speakers that will only work with big amps.

Good work around is to plug your amp into a suitable transformer conditioner.

Hi werd
almost 80% of power comes from the transformer,and about 20% from capacitors,capacitors are there to filter out the hum from the rectifier ,this had been a lesson for me when dealing with class-a amplifiers,and the filter needed to be big...

[werd]

Werd, there's ten things going on for every one you've said.

Bigger amps with larger reservoirs and higher headroom suffer less from the power problems that represent power that does not exist. Essentially the amp acts sort of like a PFC in a manner by being above and beyond the duty of needing anything near. However all the impedance etc aren't a loss of power so much as they're interfering, and usually with noise.

Large VA transformers are good for in-rush current, and very useful for when it'll cost you an exorbitant amount of space and money to populate with enough capacitance to make up for needing the efficiency of a very large transformer. It can be done easily with small devices, very large capacitor reservoirs for their size to the point where you turn it off and the device plays full volume for a few seconds. You can't do that with a Pass amp. You probably can't afford too...

The size retains thermal efficiency, particularly at 60hz, and not necessarily a relation to the amperes needed.

This is all about power delivery, not the amount. 15a is more than enough to service any Pass amp WITH EASE. But we're talking about an amplifier that has a constant current power supply so it's always using power, and sometimes more. under load the capacitors actually get a work out, so the efficiency of in-rush current means a lot. The inrush current isn't necessarily high, but it's happening a lot. It'd be wise to beef the capacitance but we're talking soft starts and CH-CHING! At least for some better capacitors.

Believe it or not, I'm on the job of a PSU board for the F's... Not the turbo though, totally unruly in size. Perhaps I'll quarter up the pieces but it destroys the benefits quiet a bit.

The idea was answering how much power do you really need. My posts leans towards lots. You are saying it can be done using smaller devices. I agree but we are talking audio here.  It's how it sounds.  The idea behind a regular toroidal is to stay stiff while power spikes into 40 50 current range. Typical amps using toroidals want the current availability. The local transformer doesn't want to supply power in that range to some little PS Like you find in a carver. it's going to go only to big power. Those amps never see that kind of recovery from the wall.
I like S Clarks remarks about the damping requirements for his speakers.