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Power Amplifier and Preamplifier Must Be Three Feet Apart?


TubeLover

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My recently purchased, older (2002 vintage) monoblock amplifiers note, in their very extensive manual, that they should never be placed three feet or less from each other. The same applies to the monoblocks and the "source'.I recall very old school warnings about this, long ago, and I'm pretty sure that it related to EMI interference concerns. However,I thought that it had, more or less, disappeared as a modern day issue.I know that the power amplifier that I was using prior to receiving the monoblocks, as well as the two before it, were located no more than six inches from the preamp, with zero problems. 

 

I would very much like to place the monoblocks, on either side of my very large DAC, on the top shelf of my audio furniture. That would require I place the preamp underneath them, probably only about a foot, to 18 inches away, although separated by a fairly heavy wooden shelf assembly. Would this indeed be a problem, as the manual suggests? The alternative is leaving the monoblocks on butcherblock platforms out in front of the audio shelf unit, and it really clutters up the room, and makes it look overwhelmed by too much spread out audio gear.

 

JC

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5 hours ago, TubeLover said:

My recently purchased, older (2002 vintage) monoblock amplifiers note, in their very extensive manual, that they should never be placed three feet or less from each other. The same applies to the monoblocks and the "source'.I recall very old school warnings about this, long ago, and I'm pretty sure that it related to EMI interference concerns. However,I thought that it had, more or less, disappeared as a modern day issue.I know that the power amplifier that I was using prior to receiving the monoblocks, as well as the two before it, were located no more than six inches from the preamp, with zero problems. 

 

I would very much like to place the monoblocks, on either side of my very large DAC, on the top shelf of my audio furniture. That would require I place the preamp underneath them, probably only about a foot, to 18 inches away, although separated by a fairly heavy wooden shelf assembly. Would this indeed be a problem, as the manual suggests? The alternative is leaving the monoblocks on butcherblock platforms out in front of the audio shelf unit, and it really clutters up the room, and makes it look overwhelmed by too much spread out audio gear.

 

JC

IIRC, this is for phono as much as anything as the signals are weak and amplified greatly throughout the chain. Stacking things closely is never really a good idea though.

Forrest:

Win10 i9 9900KS/GTX1060 HQPlayer4>Win10 NAA

DSD>Pavel's DSC2.6>Bent Audio TAP>

Parasound JC1>"Naked" Quad ESL63/Tannoy PS350B subs<100Hz

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10 hours ago, TubeLover said:

My recently purchased, older (2002 vintage) monoblock amplifiers note, in their very extensive manual, that they should never be placed three feet or less from each other. The same applies to the monoblocks and the "source'.I recall very old school warnings about this, long ago, and I'm pretty sure that it related to EMI interference concerns. However,I thought that it had, more or less, disappeared as a modern day issue.I know that the power amplifier that I was using prior to receiving the monoblocks, as well as the two before it, were located no more than six inches from the preamp, with zero problems. 

Faulty design.  Now, one might still have good reasons to buy and use such amps despite this.  OTOH, there is no way I would tolerate it.

4 hours ago, 4est said:

Stacking things closely is never really a good idea though.

Never?  Aside from thermal issues (and tube amps with out cages), why?

Kal Rubinson

Senior Contributing Editor, Stereophile

 

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2 hours ago, PAR said:

Monoblocs are usually big amplifiers and big amplifiers have big transformers for their power supply . And big transformers generate magnetic fields that can interfere with other equipment placed nearby.

And these are big tubed monoblocks, operating in Class A, with very large transformers.

 

JC

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Thanks to everyone for their thoughts on this. And Kal, I do agree with your premise. However, my apologies, I just now realized that I mis-typed/mis-stated the initial information when I started this discussion. I had meant to say was that the manuals included with my newly acquired monoblocks said that the amplifiers themselves should not be placed closer than three feet to the preamplifier or "source". 

 

As I noted originally:

 

I would very much like to place the monoblocks, on either side of my very large DAC, on the top shelf of my audio furniture. That would require I place the preamp underneath them, probably only about 12 to 18 inches away, although separated by a fairly heavy wooden shelf assembly. Would this indeed be a problem, as the manual suggests?

 

Sorry for the confusion. Your additional thoughts would be greatly appreciated. Trying the equipment positioning that I would like to attempt is not easily done. I'm dealing with a pretty severe hip injury, and the monoblocks are 75lbs each, and another piece of equipment I would have to move approaches 100 lbs. All would have to be lifted, moved and placed somewhere else.

 

JC

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8 minutes ago, TubeLover said:

I would very much like to place the monoblocks, on either side of my very large DAC, on the top shelf of my audio furniture. That would require I place the preamp underneath them, probably only about 12 to 18 inches away, although separated by a fairly heavy wooden shelf assembly. Would this indeed be a problem, as the manual suggests?

 What type of Preamp are you talking about , Valve or Solid State?

Most SS Preamps come in reasonably well screened metal cases , some even with  steel panels where this shouldn't be a problem. 

 

How a Digital Audio file sounds, or a Digital Video file looks, is governed to a large extent by the Power Supply area. All that Identical Checksums gives is the possibility of REGENERATING the file to close to that of the original file.

PROFILE UPDATED 13-11-2020

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19 minutes ago, TubeLover said:

It is a valve/tubed preamp

 

JC

 

 In which case you will almost certainly need to follow the recommendations or perhaps try a couple of sheets of steel such as in rack case top and bottom covers underneath the bottom of the wooden shelf where the Preamp sits to give some additional screening.

 

How a Digital Audio file sounds, or a Digital Video file looks, is governed to a large extent by the Power Supply area. All that Identical Checksums gives is the possibility of REGENERATING the file to close to that of the original file.

PROFILE UPDATED 13-11-2020

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I would probably just give it a try if you can manage putting the pre 18 inches away.  We'd be talking about induced signals being 6 db more than 3 feet away.  

 

Would it be stable/safe to place the monoblocks on butcher blocks on the top shelf to give a little more space from the preamp.  Such heavy things on the top of a shelf doesn't sound like a great idea for stability, but I don't know what kind of shelf you are talking about so it could be just fine. 

 

Alex's suggestion for steel sheets would help too if you can manage it.  

And always keep in mind: Cognitive biases, like seeing optical illusions are a sign of a normally functioning brain. We all have them, it’s nothing to be ashamed about, but it is something that affects our objective evaluation of reality. 

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10 hours ago, esldude said:

I would probably just give it a try if you can manage putting the pre 18 inches away.  We'd be talking about induced signals being 6 db more than 3 feet away.  

 

Would it be stable/safe to place the monoblocks on butcher blocks on the top shelf to give a little more space from the preamp.  Such heavy things on the top of a shelf doesn't sound like a great idea for stability, but I don't know what kind of shelf you are talking about so it could be just fine. 

 

Alex's suggestion for steel sheets would help too if you can manage it.  

Adding butcherblocks on the top shelf of my audio furniture unit would be easy, and is a great idea, thanks. The steel sheets would be a lot harder to manage, and beyond my abilities to implement. The shelf unit is very heavy duty, made of reclaimed redwood, so the weigh is not an issue. It currently has an amplifier nearly a hundred pounds sitting on one end without even phasing it. 

 

JC

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2 hours ago, TubeLover said:

Adding butcherblocks on the top shelf of my audio furniture unit would be easy, and is a great idea, thanks. The steel sheets would be a lot harder to manage, and beyond my abilities to implement. The shelf unit is very heavy duty, made of reclaimed redwood, so the weigh is not an issue. It currently has an amplifier nearly a hundred pounds sitting on one end without even phasing it. 

 

JC

 

If it is redwood, it is a really soft light (not dense) wood but it would float. :D

Current:  Daphile on an AMD A10-9500 with 16 GB RAM

DAC - TEAC UD-501 DAC 

Pre-amp - Rotel RC-1590

Amplification - Benchmark AHB2 amplifier

Speakers - Revel M126Be with 2 REL 7/ti subwoofers

Cables - Tara Labs RSC Reference and Blue Jean Cable Balanced Interconnects

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3 hours ago, botrytis said:

 

If it is redwood, it is a really soft light (not dense) wood but it would float. :D

Okay, given where it was made, I "assumed" it was redwood. However, its too heavy for that, and certainly wouldn't float. I just checked with the company that made it. The unit was made from Fir.

 

JC

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Redwood is a conifir.  But I have never considered it "light."  Around here, branches that fall off crush people's houses and cars, and are called "widow-makers."

 

In any case, metal (steel) shelves will do a lot more to block EMI, should it be a problem.  But if it were me, I would just test the hypothesis.  Put the preamp and/or DAC in between them where they sit now, and listen for any interference.  (I also suggest with a hip issue that you get someone else to do the heavy lifting.)

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16 minutes ago, wgscott said:

Redwood is a conifir.  But I have never considered it "light."  Around here, branches that fall off crush people's houses and cars, and are called "widow-makers."

 

In any case, metal (steel) shelves will do a lot more to block EMI, should it be a problem.  But if it were me, I would just test the hypothesis.  Put the preamp and/or DAC in between them where they sit now, and listen for any interference.  (I also suggest with a hip issue that you get someone else to do the heavy lifting.)

Very good idea, thanks for the suggestion. However, there is not room for both the DAC and the preamplifier between the monoblocks (or anywhere close by). I had thought of just placing the preamp between them, but the existing cables will not reach all the way back to the DAC if I do that. I may try to borrow a longer pair, if at all possible, just to try this out, and see what happens.

 

JC

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31 minutes ago, TubeLover said:

Okay, given where it was made, I "assumed" it was redwood. However, its too heavy for that, and certainly wouldn't float. I just checked with the company that made it. The unit was made from Fir.

 

JC

 

Fir is still 'softwood'. Also fir has more extractables that can cause issues when wet. Hardwood, like maple, oak, ash, etc. are the best for stands. And actually the best wood is chestnut.

Current:  Daphile on an AMD A10-9500 with 16 GB RAM

DAC - TEAC UD-501 DAC 

Pre-amp - Rotel RC-1590

Amplification - Benchmark AHB2 amplifier

Speakers - Revel M126Be with 2 REL 7/ti subwoofers

Cables - Tara Labs RSC Reference and Blue Jean Cable Balanced Interconnects

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11 minutes ago, TubeLover said:

Very good idea, thanks for the suggestion. However, there is not room for both the DAC and the preamplifier between the monoblocks (or anywhere close by). I had thought of just placing the preamp between them, but the existing cables will not reach all the way back to the DAC if I do that. I may try to borrow a longer pair, if at all possible, just to try this out, and see what happens.

 

JC

 

As Dennis, Bill and myself have said, ideally you need extra screening from the transformer fields. If you do have an audible problem when moving them closer, wouldn't it be possible to screw the fairly thin steel top and bottom covers from say,  a rack case underneath the wooden shelf ? They aren't heavy. It may even be possible to earth them too ?

 

How a Digital Audio file sounds, or a Digital Video file looks, is governed to a large extent by the Power Supply area. All that Identical Checksums gives is the possibility of REGENERATING the file to close to that of the original file.

PROFILE UPDATED 13-11-2020

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10 hours ago, sandyk said:

 

As Dennis, Bill and myself have said, ideally you need extra screening from the transformer fields. If you do have an audible problem when moving them closer, wouldn't it be possible to screw the fairly thin steel top and bottom covers from say,  a rack case underneath the wooden shelf ? They aren't heavy. It may even be possible to earth them too ?

I agree with this. You could easily have a piece of 10 gauge steel cut to size to go under the amps or under the shelves. Better still might be to purchase a sheet or two of Mu metal and tape it to the underside of the shelf.

Forrest:

Win10 i9 9900KS/GTX1060 HQPlayer4>Win10 NAA

DSD>Pavel's DSC2.6>Bent Audio TAP>

Parasound JC1>"Naked" Quad ESL63/Tannoy PS350B subs<100Hz

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17 hours ago, 4est said:

I agree with this. You could easily have a piece of 10 gauge steel cut to size to go under the amps or under the shelves. Better still might be to purchase a sheet or two of Mu metal and tape it to the underside of the shelf.

I think I may be able to accomplish this with a sheet of metal placed between each monoblock and the wooden surface of the top shelf. Say, 1/8th inch thick steel cut to the dimensions of the amps. Sound like it would eliminate the concerns? 

 

JC

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On 9/9/2019 at 9:38 PM, GregWormald said:

With monoblocks it is often recommended to place the amps close to the speakers and use long interconnects and very short speaker cables. How would this work in your room?

The way they are currently laid out places them close to the speakers, and very short speaker cables would be workable, but it just really clutters up the room the way things are set up. Moving them back onto the top shelf of the furniture unit would really vastly improve the aesthetics. 

 

 

JCimage.thumb.png.c9a8dba4e5f59a1aa53c6c6d79be665a.png

 

 

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7 hours ago, TubeLover said:

Based on recommendations above, I have ordered two sheets of 10 gauge (approximately 1/8th inch thick) steel sized for the monoblocks, to be placed under them. I am hoping that will eliminate any concern about issues in placing the preamp on the shelf underneath them. 

 

JC

You never did say if you were using phono or not. If not, I am sure you will be alright.

Forrest:

Win10 i9 9900KS/GTX1060 HQPlayer4>Win10 NAA

DSD>Pavel's DSC2.6>Bent Audio TAP>

Parasound JC1>"Naked" Quad ESL63/Tannoy PS350B subs<100Hz

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On 9/8/2019 at 12:52 PM, Kal Rubinson said:

 

On 9/8/2019 at 12:52 PM, Kal Rubinson said:

Faulty design.  Now, one might still have good reasons to buy and use such amps despite this.  OTOH, there is no way I would tolerate it.

Never?  Aside from thermal issues (and tube amps with out cages), why?

A phono stage should not be near the large magnetic flux fields generated by an amplifier. It is just begging for problems, even if you do not hear it straightaway. With line levels, especially balanced signals, this is much less of an issue. These are (as stated) larger tube amps that also have output transformers with magnetic fields that are modulated by the signals. I am sure one could get it to "work", but the question seems to be about functioning optimally.

Forrest:

Win10 i9 9900KS/GTX1060 HQPlayer4>Win10 NAA

DSD>Pavel's DSC2.6>Bent Audio TAP>

Parasound JC1>"Naked" Quad ESL63/Tannoy PS350B subs<100Hz

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16 hours ago, 4est said:

A phono stage should not be near the large magnetic flux fields generated by an amplifier. It is just begging for problems, even if you do not hear it straightaway. With line levels, especially balanced signals, this is much less of an issue. These are (as stated) larger tube amps that also have output transformers with magnetic fields that are modulated by the signals. I am sure one could get it to "work", but the question seems to be about functioning optimally.

Thanks, but you were correct, I have no phono in my system. 

 

JC

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