There is no sense to separate power with power amplifier. The power is the core of power amplifier, what we need do is to put it as near as possible to make strong signal amplifier.

Some do. McIntosh make one. Also Jadis made one.

VAC makes one but adding a chassis, connection cord, etc., becomes expensive, two chassis, shipping boxes, etc.  It is not necessary IMO as a manufacturer.

Happy Listening.

I have an integrated from the 80's like that.

This is an educated guess. Most amps, at the highest level are monoblocks. Most of the highest level preamps are two box (power supply separated from the amplification). So preamps are amplifying very low level signals and the important part is keeping the high energy power supply away from the low voltage amplification. In amps, the amplification is high power, so keeping the two channels separate is more important. This is so universal… it must be really obvious to designers: monoblocks for amps and power supply separation for preamps.

@emergingsoul Wrote:

Why don’t higher end amplifiers come with a separate power chassis?

See below:

Mike

Atma-Sphere MA-3

http://www.atma-sphere.com/en/ma-3.html

There are a few, but amplifiers aren’t usually as sensitive as preamps, so there really isn’t much nee for separate power supplies.

Pass labs does it in their XS series.

It's very expensive and as stated above not as necessary as in a preamp with very low level signals.

It comes down to the ratio of transformer noise to output signal: high on preamp, low on power amp.

In addition to the examples cited above, Border Patrol Audio uses separate chassis for signal path and power supply. Thomas Mayer (Germany) employs this approach with some of his amplifier models. I can see a strong case to be made for either this method and the more common/traditional mono block design.

Charles

Steve McCormack at SMc Audio is offering DNA Power Block External Power Supplies for their upgraded (and I suspect new) amplifiers.

A big reason is warranty servicing. Connection points are a leading cause of failure due to the mechanical stresses on the coupling and the connecting and reconnecting cycles, so there has to be a large benefit to cost ratio (and with a power amp there isn’t). Last thing a manufacturer wants is for word to get around that his product will be a service nightmare and ain’t worth the aggravation.

A preamplifier, on the other hand, requires space along the back for ease of access to use the input and outputs. This results in a lot of real estate taken up inside the box for the circuit boards and becomes a challenge to situate the power supply. An amplifier requires space on the sides for heat sinking the output transistors and a small footprint for the input board. The output circuit board can easily be situated vertically on the sides (and even the input devices can be fit). This leaves a lot of space inside the box for the transformer and filter caps and maybe some folded laundry. So it makes no economic sense to separate the power supply. The box needed for the amplifier passives is comparatively very small and would be a waste of metal which would be 99% air if kept at a standard size.

Isolation from induced noise vs. distance between the amplifier circuitry and the supply.

It's not a zero trade-off solution, but it certainly appeals to the separatist mind of audiophiles.

It sure would make moving monster power amps a bit easier (e.g. the Rogue Zeus is a 210 lbs monolith and a real nightmare to move), but doing it "right" would involve a lot of additional expense for the manufacturer. As others pointed out, the usual reasons to separate out PSU from phono & preamp components don't apply (as much) for a power amp. 

My new amp being built is in 3 chasses. But it is really to make it one-man portable. I specified the heaviest chassis to be 50 lbs.   So far the interconnecting cables are complete.  the transformers are in transit from Europe.

Jerry

@gs5556 You lost me at "circuit boards"...point to point is a design requirement for me.

Like these Valvet?

The only reason not to is cost. The reason to is mains isolation. The distance between them is irrelevant provided a shielded cable of suitable gauge is provided. Yes shielded as DC is easily contaminated.

If you don't have separates, and you're brave enough, open the case and with a sheet of aluminium, cut and fit shielding around the power transformer and if possible around the DC power board. Don't stop there, do all your equipment and you'll be shocked at the improvement, no matter what the purchase price.

I design power amps.

Simple: cost.  The added chassis adds a LOT of cost that could be invested in more important improvements. And it hits again raising shipping costs, also a LOT.  The advantages can be minimized through shielding of the only noisy parts - the transformers. Finally, all power amp signals are fairly large, so they are not terribly suceptible to noise compared to things like DACs and RIAA (phono) stages.  The input to a power amp is, by convention ~ 1V rmp for full output.  The input of some moving coil cartridges, by way of comparison, is 1/2 of 1/1000th V (in other words 00.5 mV). Line stage preamps fall int he middle.

That said, for a recent prototype that i constructed i did just that - mostly to make it easier to work on and experiment with tho.....but everyone seems to thinkl its cool. :-)

I would say to cost and plus designing a psu takes time and effort that people don’t want to use. Also home equipment is a copy from pro equipment and all pro equipment is made to fit in a standard 19 inch rack so since home copies they use very similar designed circuitry if not an exact copy just they don’t copy the chassis and standard 19 inch rack design. Also I know with professional amps crown xli and xls the power section is shielded fairly decently so putting a separate power block doesn’t make much sense. If you want separate power blocks I do believe Bursonaudio has them for sale and they aren’t so cheap a couple of thousand for a decent one so enjoy and know this if you listen to mostly music pro is the way to go. Kudos

They do not just copy pro equipment.

Is pro equipment up to critical listening standards?

and know this if you listen to mostly music pro is the way to go. Kudos

If this is your listening experience outcome, good for you and stick with it. I find well designed and implemented audio products for domestic environments provide a higher level of sound quality. So to each their own.

Charles

As expected, we’ve seen technically competent remarks from the younger, faster, and better looking members of this group. From an old guy’s perspective, I will add that the additional economic impact of building 2 chassis is significant. Here’s an (incomplete?) list of what happens when you split and amp in half:

- 2 chassis

- 2 faceplates

- 2 on/off switches (maybe)

- 2 shipping cartons

- 2 sets of packing materials

- 2 items to ship, handle. insure against damage

- 2 sets of service literature

- 2 sets of marketing materials (if items sold separately)

- 2 invoices

- 2 items to warehouse, inventory.

- and, last, but not least, 2 items to find room for in a rack, floor, shelf, or doily hanging from the ceiling

From a technical perspective (which I am underqualified to contribute), when high power between components is exposed to the environment, more precautions are needed in the cabling/connections. Thus, more insulation. Some have found that insulators/dialetrics are a factor in sound quality. The cost of the connections/terminators will be higher than if handled internally. But, then there exists the possiblity that the added real estate can allow for larger, more robust components. "If we just had a little more spece, we could have ...."

The two most expensive parts of a solid state power amp?

The chassis, and the power supply.

It’s a cost thing. 
 

Now, as I’m about to build a single ended EL34 power amp, I plan to put the power supply in a separate chassis. Mainly for noise isolation. But, separating the two does come with its own challenges, as had been stated above.

@muvluv What does pro gear have to do with anything as far as this topic goes? You make it seem like studio equipment gave birth to high end audio gear? How about, no…

@perkri i wasn’t talking about studio, that is more on the recording side than the playback side. Live concerts and stuff made for the pros eventually made it into the home.it happened many years ago and people forget easily the past. Also car audio helped advance drivers to handle much higher wattage than their home counterparts

Now it's car audio, two entirely different sets of parameters.

I believe early perfectionist audio systems were derived from equipment used in moving picture show houses.  There has been much evolution since.

Yeah.

Car audio is responsible for the ability of speakers to handle highpower.

Right

Small drivers, that can handle higher power came about when higher power solid state amps became a viable option as opposed to the lower powered tube amps that came before that necessitated big, high efficiency drivers in big boxes.

Got nothing to do with car audio…

@onhwy61 Wrote:

I believe early perfectionist audio systems were derived from equipment used in moving picture show houses. 

True. Like the home speakers from the late 1940's early 1950's. See below:

Mike

https://www.lansingheritage.org/html/jbl/specs/home-speakers/1948-d1000.htm

https://www.lansingheritage.org/html/jbl/specs/home-speakers/1952-c31.htm

https://www.lansingheritage.org/html/jbl/specs/home-speakers/1957-paragon.htm

Why do amplifiers come with such cheap power cords.  The power cords they come with might cost $5.  

My Musical Fidelity X-A1 has a separate toroidal power supply (its X-A2 bigger brother came with one as well).

Not super high end but a very nice "tube-like" sounding SS amp from 20+ years ago.

I just need a set of metric Allen wrenches and some thermal grease to get mine up and running again (fixed a broken lead on a wire wound resistor 15 years ago, but didn't have replacement thermal grease to use it long term - tool kit with the wrenches was stolen from my car).

Thing is that placing the power supply @ a certain distance and "angle" from the main unit improved the SQ.

DeKay

Are the power supplies usually a lot larger than the analog piece of the equation when it comes to an amp??

Seems to me the amplifier is deserving of a separate power box and all the rational to not do it doesn’t make sense. The impact on sound could be huge if done properly. All the trouble to get everything right in the chain before the amplifier and then it hits an amplifier and for some reason a major shortfall in execution occurs.

Power amps should be designed with a separate power box. Mono blocks are good because they have separate power supplies they just need to be separated it would be interesting to know how big these chassis would be. Mono blocks can be quite large how much of this is due to the power supply.

@emergingsoul Wrote:

Power amps should be designed with a separate power box. Mono blocks are good because they have separate power supplies they just need to be separated it would be interesting to know how big these chassis would be.

 Pretty big. Below are two 150 watt mono block amps with separate power supplies, four chassis.

Mike

Cool post! After learning about B fields in college physics, I've always been wary of placing transformers close to any circuitry without good shielding (despite trafo mfg claims of low b field). I use stainless cake pans. As some have mentioned above @erik_squires  it is nice to have the dc close. One idea I read about recently which seems to be the best of both worlds is to put the trafo and the first bank of caps after the rectifier then use the umbilical cable for a pi resistor (around 0R1) then place the second cap bank in the circuit chassis. Pretty cool. I'm sure SMc has implementing something similar, since he likes his clean ops DC juice close. Really close. As do I... peace

Xs300 past labs Mono blocks for a pair are $85,000.

I think they're 300 W per mono.   Doesn't seem like much power.

really nice car or a pair of mono blocks, or better still, both.

It seems 80% (totally anecdotal number) of the challenges around sound quality comes from the power supply of any complement. Very often the difference between different models from a manufacturer, at different price points, involve extremely complex work on the power supplies.
 

I was wondering if lithium battery distribution is less noisy or if changing to a solid state battery has the potential for less noise. 

@larry5729 "Why do amplifiers come with such cheap power cords.  The power cords they come with might cost $5."

Because the manufacturers know power cords make no difference to sound quality.  They surely have tested.  They don't need or want to waste money on components that cannot improve their product.  They package a good quality regular power cord usually of heavy gauge.  That is all that is required.

Those who wish to spend good $$$$ for no good reason may purchase after-market power cords at whatever price level makes them feel happy.

@larry5729 

Or, to put it another way.  Who knows more about power cords - major amp manufacturers who have been successfully in the market for decades, famous names, that employ dozens of qualified and imaginative engineers, or guys that post here in AG?

@clearthinker

Yawn, and by the way: what‘s this got to do with the topic of this thread? At least get into the relationship between power cable and umbilical, if you must.

@antigrunge2 

I am replying to @larry5729 who posted as I quoted.

Just as I am doing you the courtesy to reply to you.

Back on point, another reason why power amps don't have separate power supply chassis is because of the cost of complicated multi-strand umbilicals.

And another, these big chassis take up a lot of floor space that many of us can use more profitably and they should not be stacked because of the heat.

There.  Happy now?

@clearthinker

much better now. Did the thought occur that manufacturers may include a piece of wire fully well knowing that buyers will chose their own PCs? I very much doubt that any of them would label the generic as recommended. They certainly chose aftermarket cables when demonstrating their wares at shows, and btw: why might that be?

@antigrunge2 

Well now we seem to be locked into the PC debate.

No.  if the manufacturers thought their customers were going to buy their own PCs they would not include a PC at all, thus saving the buyers the cost of any supplied PC.  Nor in any amplifier handbook that I have seen has it been suggested by the manufacturer than replacing the power cord might have an advantageous effect on SQ.  Surely if the manufacturer believed it could, they would make such suggestion.  Its absence and the absence of a costly PC should answer the question.

Manufacturers want to sell amplifiers.  So at shows they probably choose to indulge their potential customers who think PCs make a difference, not wishing to get into pointless negative arguments with people who know less about the subject than they do.

There are some amp manufacturers who do think aftermarket power cords make a difference in sound quality.

Yes, The  AGD Audions come with quality power cords.

There are some amp manufacturers who do think aftermarket power cords make a difference in sound quality.

I do not doubt that for a moment. One thing is certain, confirmational bias is powerful. If someone is convince something will not make a difference, it certainly will not. This mindset can be extraordinarily rigid and unreceptive. Debate will be pointless.

Charles

@pwayland - The effectiveness of a tiny bit of resistance in the power supply to reduce or eliminate noise should not be underestimated.  DC sources with a tiny resistor in the way are going to perform much better in terms of noise rejection.

This is why it drives me a little nuts to see audiophiles trying to use car battery cables all the way to the transformers. The resistance and inductance between you and the rest of the world is a plus.

Frankly I don't see how marginally dripping the voltage with a tiny resistor is going to achieve anything.

Seems to me the amplifier is deserving of a separate power box and all the rational to not do it doesn’t make sense. The impact on sound could be huge if done properly.

@emergingsoul Keeping the power supply as close to the output section as possible is really important. You can have some pretty heavy current moving about and best not to have voltage drops due to any distance. Sometimes though an outboard supply has to happen; when this is the case if you do it properly you have to jump through some hoops to prevent the distance from interfering with the performance of the amplifier circuit.

Frankly I don't see how marginally dripping the voltage with a tiny resistor is going to achieve anything.

It depends on the circuit and how the resistance is applied.