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How to build quick and cheap table for my amplifier

ToTo Man said:
Question for the engineers: is an external fan that sits on top of an amplifier's vented casework and blows warm air back down inside the amplifier better or worse than no fan at all?
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I am not an engineer but I opted for blowing across rather than into the amp because I didn't want to blow dust into it. I also experimented by getting the clip on fan to suck air away from the amp but it was measurable worse than blowing air across it.
 
andrewsutton said:
Worse.
The warm air trying to rise from the amp will be blown back.
Can’t you fit the fan so it sucks air up from the heat source?
Cheers Andy.
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Sucking air up as in mounting the fan on top of the amp's vented grille but turning it upside down so that it's blowing air upwards instead of downwards, or do you mean mounting the fan underneath the amp?

What you say makes sense, but it does make me wonder why the functionality/reliability of my SR7300 was improved by blowing warm air back down inside the unit? Perhaps doing so distributed the heat more evenly across the circuitry so everything was warm instead of there being areas of concentrated heat?
 
Ibbots said:
pile of books?
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Not really the look I'm going for!

In the meantime I've cobbled together a temporary solution, - I've repurposed a pair of Atacama SE12 speaker stands into a table. Not the most elegant of solutions but at least it's sturdy and the right colour....
 
This is turning out to be more complicated than I thought. I'm shopping online for suitable materials to build a simple table (top & two sides). Material choices are wood, ply or MDF. I'm thinking the thicker the raw material the better, that way my dad won't need to mess around with gluing sheets to obtain the desired thickness. I believe 40mm is the thickest MDF you can get but 30mm seems the thickest that's widely available. Not sure if 30mm will thick enough for legs? Have also just read that you're not supposed to drill or screw into the end of a plywood or MDF sheet without additional precautions as the hold will be weak and/or the board will split. So am wondering how we secure the two sides to the top, just glue them and then use L-brackets? It sucks not having any woodworking knowledge!
 
Go to the charity shops there is always those nest of 3 tables for sale, pick which size suits you best
Very nice looking system BTW :cool:

I use one all the time just for experimenting with stuff and testing my R2Rs


Alan
 
I can’t see much thermal difference between blowing from below and sucking from above, but there will be a difference. Noise from the fan and it’s interaction with the amp might be quite different.
Marantz recommends going to considerable lengths to keep this beast cool and not doing risks failure in the short term (power transistors sudden failure risking mid range and woofers) and long term (reduced capacitor lifetime).
I guess poorly specified resistors and diodes will also be at risk.
Hifi engine has the manual for this amp.
Cheers Andy.
 
ToTo Man said:
This is turning out to be more complicated than I thought. I'm shopping online for suitable materials to build a simple table (top & two sides). Material choices are wood, ply or MDF. I'm thinking the thicker the raw material the better, that way my dad won't need to mess around with gluing sheets to obtain the desired thickness. I believe 40mm is the thickest MDF you can get but 30mm seems the thickest that's widely available. Not sure if 30mm will thick enough for legs? Have also just read that you're not supposed to drill or screw into the end of a plywood or MDF sheet without additional precautions as the hold will be weak and/or the board will split. So am wondering how we secure the two sides to the top, just glue them and then use L-brackets? It sucks not having any woodworking knowledge!
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Go and look at the underside of a chairchair, a coffee table, and a few similar things to work out how these things work. Think about failure modes, you'll never break a chair with a static vertical load but you will if you tilt it.
 
Can you Vesa mount the TV on the wall and stick the amp on the top of the rack thing? TV might be a bit high, but still an option.

PS I’d dump the subs and get a wider table, but I don’t like subs! ;-)
 
If you stick with the table idea then you could go to your local Champion Timber depot (or similar timber outlet rather than B&Q etc) They’ll happily cut down a sheet of birch ply for you into multiple pieces of whatever size suits your amp. You could then just glue them together to end up with something similar to those speaker supports.
 
Tony L said:
Can you Vesa mount the TV on the wall and stick the amp on the top of the rack thing? TV might be a bit high, but still an option.

PS I’d dump the subs and get a wider table, but I don’t like subs! ;-)
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I've been trying to persuade my dad to wall-mount my Plasma TV for years without success! If I did free up the top of the rack I'd probably use that opportunity to re-instate my turntable, as I don't like the aesthetics of a power amplifier above eye level (wherever possible I prefer to be looking slightly down on my gear as that way I get to appreciate its design in 3D).
 
If I can find a ready-made table of suitable width and depth then I can saw the legs down to get to the desired height. It would need to have a fairly minimalist design through so that there would be enough room underneath to put my Mac Mini and be able to get my hand in and out to switch it on. (Life would be so much easier if Apple put a power button on the front of the Mini or, even better, on the damn remote!).
 
ToTo Man said:
If I did free up the top of the rack I'd probably use that opportunity to re-instate my turntable, as I don't like the aesthetics of a power amplifier above eye level (wherever possible I prefer to be looking slightly down on my gear as that way I get to appreciate its design in 3D).
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In that case I’d be inclined to swap the Mac Mini onto the wooden rack and just have the Yam on a good solid 2” thick chopping board or whatever on the floor in front. I’ve done this many times in the past with my kit, in fact my Akai reel to reel is currently sitting on one to the side of my table as there is nowhere else to put it. I’ve run the Leak here in the past too. The chopping board ensures any cooling vents etc work properly and lift the unit up high enough off the floor that you can’t smack into it with a hoover. You can of course still trip over it, which I have done!

PS Here is what I mean:

47874374291_200495c35d_b.jpg
 
Tony L said:
In that case I’d be inclined to swap the Mac Mini onto the wooden rack and just have the Yam on a good solid 2” thick chopping board or whatever on the floor in front. I’ve done this many times in the past with my kit, in fact my Akai reel to reel is currently sitting on one to the side of my table as there is nowhere else to put it. I’ve run the Leak here in the past too. The chopping board ensures any cooling vents etc work properly and lift the unit up high enough off the floor that you can’t smack into it with a hoover. You can of course still trip over it, which I have done!

PS Here is what I mean:

47874374291_200495c35d_b.jpg
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I'd considered this, and also perhaps raising it slightly so that it could be slid in and out of the bottom shelf, but sadly this would be too low for access to the controls on the face plate (I struggle to bend down). On the other hand, I don't access the controls that often so perhaps I wouldn't be sacrificing that much in terms of usability by lowering it.
 
Since pulling my amp forward out of my rack the surface temperature of the top plate, according to my laser thermometer, has dropped from the low 40's C to the mid 30's C. It feels pretty tepid to the touch now. As a comparison the surface of my DAC runs at a steady 33'C and my Mac Mini around 30'C. This is with a room temperature of around 18'C-20'C and no through-drafts. My equipment will obviously run a bit hotter than this in warmer weather and cooler if I leave the door open etc. The amp is about 3/4 of the way out of the rack at the moment, which leaves around an inch or so of grille vents still inside the rack. I'll probably end up pulling it forward a little more so that all the vents are exposed. It looks a f*cking mess at the moment TBH, but I think it's because the Atacama SE12 stands are way too chunky and the beige cork heat mats don't help aesthetic matters either, but they were the only things I could find the that were the correct height! On a more positive note, I think the Mac Mini looks pretty cool on the 20cm high Gale speaker stand I've put it on. If only I could find a pair of similar 30cm high stands for the amp! (I've put a wanted ad in the classifieds but am not holding much hope).

47837245702_d1264724f3_b.jpg
 
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ToTo Man said:
Since pulling my amp forward out of my rack the surface temperature of the top plate, according to my laser thermometer, has dropped from the low 40's C to the mid 30's C. It feels pretty tepid to the touch now. As a comparison the surface of my DAC runs at a steady 33'C and my Mac Mini around 30'C. This is with a room temperature of around 18'C-20'C and no through-drafts. My equipment will obviously run a bit hotter than this in warmer weather and cooler if I leave the door open etc.
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I’d say that was a significant temperature change and proof that racking it that tightly is not good for it. I know electrolytic capacitors age very differently depending on operational temperature, so the cooler the amp the longer it will last before issue/requiring service.

PS Regarding the Mac Mini, why not just set it to ‘wake on LAN’ and leave it sleeping. You could then hide it anywhere and just wake it up with a phone/tablet app. You’d need to use a direct ethernet connection for this to work, but it might be an option if your router is near by.
 
Can you cut a hole in shelf 2 and mount the fan flush with the top surface? Make the fan draw air upwards so it pulls the warm air out from below, assisting the natural airflow. Then make a sub-shelf with feet in the four corners to give about 25-30mm gap (18mm ply or similar) and paint it black / or clear wood finish and place this on top of the shelf with your gear on top.
 
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