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Better to not share a preamp in the same outlet or strip as the amp?

108.14.104.71

Posted on January 15, 2017 at 09:06:39
I tried plugging my preamp into really the same outlet in the wall but another strip. The outlet has been upgraded to hospital grade. 2 plugs, one a power strip PS audio the other a radio shack power strip. I plugged the preamp into the radio shack power strip and it sounds better.

I do have a very old monster power conditioner. Does anyone think that would be better to put the preamp on its own separate power conditioner at this point?

My cables are all over the place, I have to figure this out, thanks for any help.

 

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RE: Better to not share a preamp in the same outlet or strip as the amp?, posted on January 15, 2017 at 10:01:21
jea48
Audiophile

Posts: 6770
Joined: January 5, 2005
From my personal experience I have the preamp and power plugged into the same 20 amp dedicated circuit wall duplex receptacle. Both pieces of equipment are analog.
( 120V 20 amp dedicated branch circuit, with #10-2 with ground NM-B cable, Romex is a Trade name of NM cable).

The thing that must be considered is the size of the branch circuit wiring used, and the length of the branch circuit wire from the electrical panel to the wall receptacle outlet. You do not want the AC mains voltage fluctuating, bouncing around, caused by the dynamic load placed on the power supply of the amp, when driving the amp playing a dynamic musical source through the amp. One reason many use #10awg wire for the branch circuit wiring for a 20 amp circuit. For a short branch circuit run #12 may be fine. Though it may depend on the size of the power amp and how hard it is driven.

As for any digital equipment, I personally have found it is best to feed it from another dedicated circuit. The idea, theory, is to decouple the digital equipment power supply/s from the analog equipment power supply/s.
I suggest you search the archives, here on AA on the subject, of Al Sekela and rcrump just to name two.

//

EDIT:

Impact of fluctuating AC mains voltage on a power amp's power supply.


atmasphere,

5,153 posts 06-03-2014 10:46am

With power cords its all about voltage drop across the cord. Some of that is at 60Hz, and some of that is much much higher- well above 30KHz-100KHz depending on the power supply in the unit with which it is being used.

I've seen a 2 1/2 volt drop rob an amplifier of about 30% of its output power. The cord was rated for 10 amps, and the draw was about 6 amps. This measurement was done with a simple 3 1/2 digit Digital Voltmeter.

The more insidious problem is high frequency bandwidth. The power supplies of most amplifiers have a power transformer, a set of rectifiers, and a set of filter capacitors. The rectifiers only conduct when the power transformer output is higher than that of the filter caps. So:

When the caps are fully charged the amp is able to play. As it does so, the caps are discharged until the AC line voltage waveform gets high enough again that the rectifiers in the power supply are able to conduct. Depending on the state of charge of the filter capacitors, this might only be for a few microseconds or it might be a few milliseconds. Either way, the charge is a spike which has very steep sides- and requires some bandwidth to make it happen.

If the power cord has poor high frequency response, it will current limit on these spikes. This can result is subtle modulations in the power supply or even a sagging power supply voltage.

Romex wiring found in many buildings actually works quite well. So it really becomes all about that last few feet and also how well the power cord is terminated- molded cords generally are not terminated very well. If the ends of your power cord get warm after a while, you know you have a problem!

This can be measured, its quantifiable and also audible as many audiophiles know. Anyone who tells you differently probably has not bothered to do any measurements- please refer them to this post.

The same holds true for VD, Voltage Drop, on branch circuit wiring.

 

RE: Better to not share a preamp in the same outlet or strip as the amp?, posted on January 15, 2017 at 10:44:06
SgreenP@MSN.com
Audiophile

Posts: 3538
Joined: April 23, 2007
I like to keep my amp plugged separately

 

RE: Better to not share a preamp in the same outlet or strip as the amp?, posted on January 15, 2017 at 10:48:43
Jack G
Audiophile

Posts: 9740
Joined: September 24, 1999
Since your preamp is mostly passive, it may not make much of a difference.
That said, I always like to keep class D amps separated from the rest of the electronics. It's a good practice.
Jack

 

+ 1 on the Class D amp/s on their own dedicated circuit. nt., posted on January 15, 2017 at 11:45:57
jea48
Audiophile

Posts: 6770
Joined: January 5, 2005
nt.

 

RE: Better to not share a preamp in the same outlet or strip as the amp?, posted on January 15, 2017 at 13:16:18
pictureguy
Audiophile

Posts: 22597
Location: SoCal
Joined: October 19, 2008
I don't mean to be picky, but just WHAT does 'seperated' mean?
Different drop from the box?
Different leg altogether? (other side of the box)
Or will just a different circuit from the Power Conditioner do?

My 'd' amp was thru its OWN circuit and a PSAudio Soloist Outlet. Rest of stereo was thru a Power Conditioner on a public circuit in the house.

Never any interaction that I could hear.
Too much is never enough

 

Do you have, posted on January 15, 2017 at 17:12:46
E-Stat
Audiophile

Posts: 37652
Joined: May 12, 2000
Contributor
  Since:
April 5, 2002
any dedicated circuits going to your panel?

At the very least, I would recommend getting control of your cable rat's nest.

 

RE: Do you have, posted on January 15, 2017 at 18:08:43
I do but it was used for central AC.

I'll read more up on this, thanks to all for the very helpful advice.

 

"I like to keep my amp plugged separately." +1 nt, posted on January 15, 2017 at 19:38:51
R Browne
Audiophile

Posts: 1710
Location: So. Cal.
Joined: January 14, 2002
nt

 

RE: Better to not share a preamp in the same outlet or strip as the amp?, posted on January 16, 2017 at 04:50:05
Mechans
Audiophile

Posts: 1804
Location: East Coast
Joined: May 23, 2004
I dunno about the physics/electrical parameters etc. all I can tell you is that I use different outlets from the same dedicated circuit. This results in absolutely beautiful music with no apparent degradation in sound. I respect Ralph Karsten's thoughts and suggestions. FWIW really same power source no problems.

 

Ideally, posted on January 16, 2017 at 05:59:23
E-Stat
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Posts: 37652
Joined: May 12, 2000
Contributor
  Since:
April 5, 2002
you would use one or more for your audio gear. I put two in my dedicated listening space.

 

RE: Better to not share a preamp in the same outlet or strip as the amp?, posted on January 16, 2017 at 10:37:11
jea48
Audiophile

Posts: 6770
Joined: January 5, 2005
Just to be clear, I posted Ralph's Agon quoted comments only for voltage drop, as that was the purpose of his post on Agon.

As for your experiences using a single branch circuit to power all your audio you are not alone. Many others do as well.

Could it sound better using a single dedicated branch circuit strictly for your audio system, instead of a shared convenience 120V 15 amp outlet branch circuit?

Could it sound better using at least two dedicated branch circuits, one for the analog equipment and the other for the digital equipment?

All that really matters is you are happy with how your audio system sounds.

//

About 8 years ago a friend of mine that owned a B&M Audio/video store ask me to install some power on a new wall he had built. He said he didn't really care where I fed it from. I talked him into installing 2 new 20 amp dedicated branch circuits to the wall where the audio equipment rack would be located. One for analog the other for digital. (Wiring material used, two solid core 12-2 with ground MC aluminum armor cables)

I happened to stop in his place one day just to talk and look around. I noticed all the equipment on the rack was plugged into one Box Store bought power strip that was plugged into a receptacle of one of the dedicated circuits.

My friend, the owner, was not there at the time but one of his sales guys was there. I should mention the guy has been in the business for many years and has a good ear for hearing differences of audio equipment and speakers.

I asked the guy why is all the equipment plugged into one power stripped plugged into only one dedicated circuit? I reminded him I installed two, one for analog the other for digital. He replied the way he had it was to make his job easier. He then added most the people that walk through the door could not hear the difference.

I then asked him, do you think you could hear any differences? He responded, probably not.... You would be surprised how may audiophiles think the same way. How possibly could the AC mains power have any impact on the sound quality of an audio system?

I asked him if he would like to participate in a quick listening test. He said sure, why not.

Just going from memory the amplifier was a Marantz integrated and the CDP was I believe a Marantz or maybe a Cambridge audio. I don't remember the speakers. They might have been Monitor Audio or Paradigm. I do remember the pair that were hooked up at the time were floor standing and sounded pretty good connected to the Marantz amp.

For the blind test we found a good size piece of cardboard to hide his view from the two dedicated circuit wall duplex receptacles and from seeing what I might be doing. Though there was other equipment on the rack only the CDP and amp was used for the listening test.

The listening test.
I asked the guy to pick out a couple of CDs he was familiar with. CDs of a female artist and maybe some solo piano segments preferred.

I first let him listen to the system as he had it connected to the power strip, plugged into the wall receptacle. I then plugged both the CDP and the amp into the same duplex receptacle, not telling what I had changed. I then said ok I am ready for him to listen to the track again and listen for any differences. Believe it or not I could hear a slight difference for the better right off the bat. The guy listened for only about 30 seconds and then said let him listen to it again the other way. He had me repeat the A/B comparison only a few times and picked the sound that sounded best to ears. I then removed the cardboard so he could see both the CDP and amp plugged directly into the same duplex receptacle.(I should mention here the power strip was not an audio grade power strip by any means. The purpose of test was to set up a level playing field for the next test that would follow.

Test 2.
Could he hear any differences when the CDP and amp was plugged into the same duplex fed from only one branch circuit, and when each were fed from their own dedicated branch circuit.

For this test A/B/X testing was used. Cardboard screen was again used so he could not see what I was doing.

I allowed him to listen to A or B upon request. He then could then ask to listen to X again.

30 seconds or so of listening some times less was all that was needed for him when listening to a song. Just going from memory he picked when I had the CDP fed from one circuit and the amp fed from the other circuit sounding the best to his ears every time. After about 6 to 8 trials he said that's enough. That one sounds the best, remove the piece of cardboard.

I said what do you think? He agreed it definitely sounded better when the CDP was plugged into one circuit and the amp plugged into the other..... But then he added but most of the people that walk through the door won't know the difference. Especially if he doesn't tell them or show them.

When I went back a few weeks later everything was plugged into the single plug strip and fed from one wall outlet circuit.

 

What else shares the outlet? 15amp with only audio? or several other non audio things?, posted on January 16, 2017 at 10:59:43
When I was young I lived in an old apt with two units sharing one 15 amp fuse. Naturally this compromised the amount of juice i had.
Now I live in an apt with 100 amps.
My stereo has it's own 20 amp circuit to itself.

The Monster may or may not help. You have to actually try it out.
I had two Monster, and now use a Furman REF20i.
In my experience the tradeoff is greater clarity with a slightly leaner sound in general from using a conditioner. tighter bass with vs wooley bass without..

 

"same branch".. just a reminder to anyone do NOT use both branches of 240, posted on January 16, 2017 at 11:15:23
The main danger of desiring to use two or more outlets is the possibility of having BOTH branches of the 240 connected through the IC.
No problem until a fault. Then you could get 240 volt differential possible through the IC connecting the two separate 120v branch.
(combined they make the 240 volt differential)

Like I wrote, this is not usually ever an issue. but it can accidentally create a potential lethal voltage.
You can check to see if both AC duplex are from the same 'side' of the 240v. buy using a voltage checker from both 'hot' sides of the two duplex. If you get O voltage. then they are the same. If you get 240v, then they are from the two different sides.
If you have no idea which is the hot.. Then the readings would be (trying all four wires with each other through a voltmeter for AC level) same: 0v(both hot) 120v 120v (hots to other neutral) 0v(both neutral). or if not same: 240v(both hot), 120v 120v(hots to other neutral) 0v(both neutral)

 

RE: What else shares the outlet? 15amp with only audio? or several other non audio things?, posted on January 16, 2017 at 11:16:19
15 amp, just audio equipment.

I use a PS Audio quintet, Shunyata power cord going into it.

It is ok for now, I don't anticipate too much more, nothing like building a separate audio house or anything like that :)

I have a monster conditioner, I figured I would use that, but wound up plugging in the preamp back into the PS Audio and basically gave up, you can only strive for so much.

 

Both dedicated circuits were fed from the same Line ,Leg, in the electrical panel. , posted on January 16, 2017 at 13:11:43
jea48
Audiophile

Posts: 6770
Joined: January 5, 2005
Sorry I forgot to mention that.

Though I should mention I have read posts where a user had big 600 watt mono block krell amps fed from two dedicated circuits installed on Line 1 and Line 2, (240V potential between the 2 hot contacts of the 120V dedicated branch circuits), without any adverse SQ problems.

In this instance the importance of the integrity of the electrical safety
equipment ground is of the upmost importance. It could/would prove to be quite dangerous/lethal if the equipment ground was defeated/lifted on either amp or both.

//

3+4=5,

You got me thinking while reading your post. A while back on the Agon forum I was responding to a guy that lives in Chicago Il. Chicago has some old out of date electrical codes that are still required by their city AHJ, (Authority Having Jurisdiction). Still to this day branch circuit wiring must be installed in EMT conduit inside a single family dwelling unit.

What really peaked my attention was the use of multi wire branch circuits where the neutral is shared with two hot wires, (two separate 120V circuits). One must be fed from one Line, leg, the other fed from the other Hot Line, leg, in the electrical panel......
(Note: Only the imbalanced load of the 2 hot conductors returns on the neutral conductor to the electrical panel.)

For any of you that live in Chicago be damn careful if you personally try replacing any wall duplex receptacles convenience outlets where the device is used as a junction point for the shared white neutral conductor. You might have the HOT circuit feeding that duplex receptacle de-energized but if the other hot circuit of the 3 wire multi conductor branch circuit is still energized you may receive a lethal electrical shock when breaking, disconnecting, the neutral wires from the duplex receptacle..... TAKE A GOOD LOOK INSIDE the wall duplex receptacle outlet box for another HOT circuit wire passing through the same box.

I have also found Florida use to use a lot of 3 wire with ground Romex multi wire branch circuits.

Informational note:
Just going from memory I believe the 2008 NEC Edition starting requiring all multi wire branch circuits must be fed from a multi pole breaker or breakers using an approved common trip handle.... That does not mean the AHJ in your area adopted the change......

//

Check out the Link/video below on how a multi wire circuit shared neutral works.



 

To tone it back a notch, posted on January 16, 2017 at 13:22:41
This is all absolutely crazy but completely right,

To tone it back a notch, I have a power strip with 5 zones. I made one zone dedicated to the Hypex amp and bass has improved, the thing is I have the preamp and DAC on the same zone, immediate difference, much veil, but very good, also my preamp is breaking in at the same time I am going nuts.

Thanks again for all the help, this is much fun.

 

RE: Better to not share a preamp in the same outlet or strip as the amp?, posted on January 16, 2017 at 19:51:55
Duster
Manufacturer

Posts: 17117
Location: Pacific Northwest
Joined: August 25, 2002
Based on your description, the only benefit of plugging your preamplifier into another AC outlet is too keep the AC plug away from the AC plug for a high-current power cord application, which may pollute the lower-current preamplifier power cords AC plug via the more powerfully radiated magnetic fields created by the power cord conductor to AC plug termination points. That said, I share a single Oyaide AC outlet in my computer workstation system with the preamplifier power cord and power amplifier power cord, since the sonic betterment that the single Oyaide AC outlet provides is greater than the downside of potential pollution due to radiated magnetic fields, in that particular case.

 

RE: Better ?, posted on January 17, 2017 at 14:54:50
bare
Audiophile

Posts: 1879
Joined: April 14, 2009
Hmmm I have dedicated Power circuits to My Audio room.
For many years now
Did it when my house was being built.
In truth it makes NO audible difference when I use an extension cord to another room.
Unless there are wiring issues in your residence (very Common unfortunately)
It's IMO just another OCD Audio Weenie fixation... like power cords :-)

 

From One New Yorker to Another..., posted on January 19, 2017 at 13:42:41
Jim Hodgson
Audiophile

Posts: 399
Location: New York City
Joined: March 9, 2006
The quality of our power represents a real hurdle.

"Does anyone think that would be better to put the preamp on its own separate power conditioner?"

It may be better to run your entire system from a power conditioner.

 

RE: I'm using a "Monster" Power Conditioner, posted on January 20, 2017 at 11:06:34
mr.bear
Audiophile

Posts: 4167
Joined: November 13, 2001
My system all runs from a single outlet to the Monster in our (rented) condo, no way around it in practical terms. The TV is on a separate outlet, as is the subwoofer, but all are on the same house AC circuit.

My system is quiet including the MM phono, vintage preamp used as a phono stage, monstrous Lexicon digital A-V preamp, and power amp-- all plugged into the appropriately labelled AC outlets on the back of the Monster. Good enough for my performance objectives.

"Good enough?" I think that the crux of the biscuit is how resolving is your system and your listening habits. My experience in avionic instrumentation and hi-fi say that you can hear ANYTHING- and actually objectively measure something about it. (Building speakers, I've heard the difference in freakin' solder formulas but it was a millionth of a zillionth of 1 percent and neither was "better.") You will definitely get an impact from the purchase of the new ultra-expensive power components, but you might get as much or more by removing, dragging around, and reconnecting existing cables. Happens all the time in avionics. The fallacy of "All things being equal" sure comes in to play since they can never be!

At one time I had a separate 20-amp circuit wired to a much higher resolution stereo music system in a former residence. It made no discernible difference except perhaps for providing the electrician's boat payment that month. So I'm a prejudiced Bear-- the money seems much better spent on buying recordings!

 

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