is it ok to sit audio equipment directly on top of one another?

[alpina]

hi all,

just wondering if it's ok to sit gear on top of one another rather than on shelves? obvious concerns are weight and ventilation.

cheers,

julie

[alebonau]

not usually a good idea alpina as heat from one component rises directly into another. You've mentioned weight already - puts a bit of load on the component right down the bottom that it probably wasn't designed to take.

another issue is electro/magnetic/RF interference that you might get from one component that impacts on another - ie one component sitting in a magnetic field generated by another component. Or one component picking up RF or other interefernce of another.

Shelves plus a bit of space between the shelves and the components help on the heat side to allow the components a bit of space to breath plus give that bit of space and can act as a bit of physical barrier to any sort fo intereference as well.

That said with some components eg. stacking some thing obviously pretty light ontop of another component that does not get very hot may not be an issue.

I only stack one of my components a digital TV stb on top of my universal DVD player. All else is in shelves with room ot breath.

If your finidng racking expensive or hard to find exactly what you want, you can just buy square powder coated aluminium tubing and plastic fittings, they cut it to size and you jsut push the bits togetherto make some very sturdy racks yourself.

this one here, holding the two power amps, I made myself, quite inexpensive, does a great job and looks pretty smart I think.

[alpina]

nice rack.

one reason i ask is because most racks look funny to me as the components are not equally spaced.

like the neatness of putting them one on top of the other but fully understand how impractical that is.

the design of our custom rack is really slowing down our whole system and the completion of our renovation.

will perservere

julie

[Karma]

HI Julie,
I started to answer your question but the post got out of hand. So, I posted as a new thread. Here is the link. It's more than you ever wanted to know.

http://www.htguide.com/forum/showthread.php4?t=19823

Since this probably not the answer you need, I will say this. Low power, cool (heat, that is :W ) equipment can be sucessfully stacked without harm. Heat producers like receivers and power amps should not be stacked. In the referenced post I broke all my rules and advise. Can you trust someone like me?

Care must be taken to prevent heat build up. Otherwise, it is a harmless practice.

Sparky

[David Meek]

Julie,

In general it's a baaaaaad idea. :nonod: Not only for ventilation/heat dissipation, but also because of possible vibration transfer.

But, if you have some lightweight components that don't generate appreciable heat, then you can try stacking them. Just make sure that they have their "feet" on them so that air can move between. Try it and see if the collective amount of heat output is noticable and whether there is a loss of audio/video quality.

Good luck.

[Karma]

Vibration and EM Noise; Cause for Concern?

HI David and alebonau,
I have expressed the same concerns about vibration and electromagnetic noise to others. I generally follow my own advise about stacking. But like so many things in hi fi, is this just paranoia or fact based on experience? The only fact I can really substantiate is heat build up.

If vibration is the issue, what is the vibration source? If there is a source, does it actually couple to the stacked equipment? The only source that seems significant is the rotating disk on a DVD/CD player. In my experience repairing many CD players, vibration is not a problem. Even if there is vibration, all good equipment have shock isolating feet. Plus, the vibration must actually move the equipment mass. Seems generally unlikely.

Some have claimed that the sound vibrations in the air could couple into the equipment and act as a vibration source. I agree, that can happen but does it happen?

I have run some tests you might find interesting. My main system is based on tube equipment; both preamp and the main speaker amp. Tubes, as you may know, are infamous for microphonic problems. The subwoofer amp is solid state Levinson. I have paid close attention to vibration treatment. I was curious to see if the system was shock and vibration sensitive.

I ran a pulse/function generator, the kind where you can program the number of sine wave cycles in a burst and control the burst duration and repetition rate, into my sub amp. I monitored the output of the main tube amp and preamp with a very sensitive oscilloscope. I could measure micro volts. The preamp was switched to the MC photo input, presumably the most vibration sensitive mode. I placed the stylus on the turntable platter. The turntable was not turning. I then triggered the generator to produce a series of very low frequency, high power sine wave bursts through the subs. Believe me, every loose thing in the room was rattling. All, that is, but the tubes. If the amps or the turntable were vibration sensitive I would be able to see it indicated by a varying voltage on the scope. I saw NOTHING. I tried different frequencies of sine wave bursts to identify resonances but found NOTHING. I even tried a continuous frequency sweep. NOTHING! I was pretty happy with my vibration reduction program.

As for electromagnetic noise (EM), there is definite potential for coupling. The only EM field that is strong enough to couple to stacked equipment is 60HZ from the power supply. It could happen but if it does you should be able to hear it allowing one to adjust the equipment positions to compensate.

The one EM case that is clearly a problem is phono pre amps for MM cartridges and pre pre amps for MC phono cartridges. The preamps gain is so high that very small fields can be a problem. This is a case where I try to keep the pre amp circuits as far away from EM fields as possible. But again, if there is a problem you can hear it. Ordinary, common line level signals, with which most folks are concerned, are very noise resistant.

I'm just thinking out loud. We are attacked by so much snake oil that sometimes it is useful to stand back and take a second critical look.

I would appreciate your ideas on this. Maybe we can shed some light on a non-problem. Slay urban legends-that's my motto.

Thanks, Sparky

[Shane Martin]

Karma,
A cheap tweak regarding vibration reduction is to mess with either vibrapods or an aurelex subdude for your sub. Both IMHO have convinced me that vibration is important and not expensive to fix.

It is a bad idea to stack and mainly because of ventilation.

[Karma]

HI Shane,
You are sounding very dogmatic. What if the equipment puts out little heat? Is it still a bad idea?

Most of our equipment is in the low heat class. So, what's the harm? Do you not agree?

Sparky

[Vinny]

I have mine stacked together but only for the Panny XR-55 which is a digital reciever(digital amp) and barely producing any heat and 2 DVD players over it(which has nearly no heat output). Otherwise I do not think you should do it especially with solid state amp. In terms of weight it's always physics issue of will the bottom one crack if you put some weight more :B . Obviously you do not want to hit the limit whole time but otherwise not a big deal on having more or less weight on something stationary.

[Glen B]

I've been stacking my HT components for years with no problems. I just use common sense in placement. My receiver is the only item that generates any significant amount of heat and I make sure it has reasonable ventilation. With my 2-channel system its an entirely different story. With a large amp and line conditioner both with massive transformers, I make sure that each unit is on its own shelf with adequate space in-between for ventilation and to avoid interference from magnetic fields.

[Vince Helm]

No!!!!!

[Shane Martin]

What if the equipment puts out little heat? Is it still a bad idea?

No but I like to be sure. Why take chances? Plus to me stacking looks terrible. That's the reason I bought an equipment rack. They aren't expensive and hide wires quite well.

[alebonau]

HI David and alebonau,
~

I would appreciate your ideas on this. Maybe we can shed some light on a non-problem. Slay urban legends-that's my motto.

Thanks, Sparky

karma,

with my system I've had most components for over a decade and moved with them quite a few times and had them in various orientation in the different houses I've lived in.

With my previous 2ch pre and mono blocs, I've had one of the mono blocs temporarily stacked on top of the pre and with both running cool as cucumbers never had any issues heat wise or noticed any impact sonically whether via EM or RF intereference between the components. Ofcourse a bit of common sense should still apply. I'd never have stacked the pre on top of the mono bloc - or two mono blocs on top of each other - as heat rises. I've also had my mono blocs and pre stacked on separate shelves and also with the mono blocs placed right next to each speaker without any sonic impact due to vibration.

With my curren pre-pwr. Theyve got massive torroidals inside and I've had the pwr amp temporarily stacked above the pre with no noticeable sonic impact from RF or EM intereference. Again common sense prevails. The pwr amp does run warmish and I'd never run the pre amp stacked above the pwr amp. That said the way I have all the components stacked now is with them each on their own shelf with plenty of breathign space - that way with any subtle effects the way I'm looking at it I'm not putting anythign at risk if I dont have to.

Re other components, I've had my CD transport, record player and other components either within a foot from a speaker or meters away with no somic impact either way due to vibration. Now perhaps there has been no impact due to the design of the disc player - its a teac esoteric utilising the vibration free rigid disc clamping method. And the record player is a rega and rega them selves say they have gone to extraordinary effort with the vibration dampening feet and are quite specific to not place the record deck on any special vibration isolation tables or anythign else.

Its all about commonsense. I never stack components unless I absolutely have to. I try keep plenty of breathign room between components(to minimise possibility of heat/vibration/RF/EM intereference effects) and stack each on its own shelf to minimise the possibility of stress/load effects on the load bearing components and plus too to provide a physical barrier of space and the shelf between the components. My AVR and digital stb and universal player is also physically separated from my 2ch gear to minimise any potential of intereference between the two systems.

I don't say every one else needs to do these kind of things, its jsut what I do, for my own peace of mind. AS I think few have suggested best to let common sense prevail.

[Karma]

HI All,
OK, we have a comment for good looks, one for common sense, one for taking no chances damn the evidence, and one for the practicality of stacking the right choice of equipment. We are getting somewhere.

What I have not yet heard is proof positive that, a priori, stacking is a bad practice in general. Hmmm, sounds like we are dealing with, at least in part, an urban legend. Makes my mouth water!!

Audiophiles are, I think, a very conservative gang. If someone introduces an idea that offers the even the remotest possibility of sonic improvement, no matter how counter intuitive, we tend to adopt it. Sometime the idea is great and is adopted across the industry with lasting effects. Two come to mind: designer cables and Tip Toes (spikes). But many are simply snake oil. And many others are urban legends that may or may not have any technical basis at all.

Still looking for some proof. Good appearance (with which I agree and think is important but very personal) does not count, Shane. This is a technical issue, not aesthetics.

BTW, much equipment is designed to be stacked. Pretty much anything without vent openings can be safely stacked without the worry of heat. I think the manufacturers have conceeded that how the consumers use their equipment cannot be controlled.

Sparky

[Sim reality]

I think this "rule of thumb" versus specific circumstances...

It ultimately boils down to how the Manufacturer align the heat sinks... If the heat sicks are pushed out to the outer edges of the case then side ventilation is more critical then vertical ventilation. If the heat sinks are parellel with each other so that you have heat sinks in the middle of the case then vertical ventilation is critical and you cannot stack them without risking critical heat buildup.

I personally would stack the sources (CD, Tuner, DVD) with pre/pro as a sort of middle ground (doing the "hand" heat test) and try and not stack the amps (although a lot of manufacturers are designing heat sinks to be on the side of the cases making more use of side ventilation).

Unless of course they were Digital amps (which usually use some sort of feedback mechnism to "fix" the driving voltage anyways and don't produce much heat)...

[Tha Freak]

I temporarely set my TT on top of my RSX-1055 (and using a Cambridge Audio 540P phono stage)...

could tat be the "new" source of "hummm" from my sub??

haven't noticed any humm from my sub before...

[Karma]

HI Freak (I'm one too!)
Yes, I would be very suspicious of your turntable location. The cartridge output (don't know if you have a MM or MC type) is very low ranging from milli to micro volts. These require very high gains in the preamp which makes turntables and cartridges very sensitive to EM (60Hz) noise. Your power amp puts out a significant 60Hz EM field. There is a very good chance the cartridge wiring is picking up that noise. Move your tt. There could be other causes such as ground loops. They are a lower probability.

If that is your problem it will only show up if you have selected the phono input.

Your case underlines my point above. If 60Hz noise is a problem, you will hear it. Rearrange the equipment to solve the problem. No need to guess. More fuel for the urban legend burning party?

Sparky

[Shane Martin]

Karma,
What I do know is my equipment all generates a significant amount of heat including my HD DVR. I'm just waiting for someone to tell me I bought inferiorly designed equipment which is all too often a skeptics response.

[aud19]

Karma,
What I do know is my equipment all generates a significant amount of heat including my HD DVR.

Any cable box I've owned gets QUITE warm/hot. My HD DVR is even hotter. As such it sits at the top of all my gear

[David Meek]

I'm just waiting for someone to tell me I bought inferiorly designed equipment which is all too often a skeptics response.

Okay Shane. You've obviously bought inferiorly designed equipment which is causing your heat and vibration issues.

JUST KIDDING, bud! :rofl:

[Karma]

HI Shane,
No, I won't say that. You have to go with what you have and make judgments accordingly. It is interesting that my Sony HD DVR generates almost no heat and is stacked on the bottom with my CD recorder on the top. Heat is not a problem in my case.

You gotta do what you gotta do, right?

Sparky

[David Meek]

All kidding aside, I've had my equipment set up in variations of all of the above, but my ears tell me that it performs at its best when it sits on a heavy-duty steel isolation rack which has steel BB and sand-filled legs, with VibraPods resting on the wood shelves, with glass panes sitting on top of the VibraPods and the components each sitting on their own panes on individual shelves. Minimizing heat buildup is just good common sense for aiding in longevity/performance for components, and minimizing vibration is also good for performance.