Case Damping

Discussion in 'DIY Discussion' started by cookiemonster, Jul 6, 2003.

  1. cookiemonster

    cookiemonster

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    Whats the best/cheapest stuff to use for damping cases and where can i get it from.

    Anyone seen RA's new 'The Damper' - £20 for ~30cm*20cm:eek: blimey - no thanks.

    I'd like something cheap, whihc i can also cut to size and affix easily.

    Cheers
     
    cookiemonster, Jul 6, 2003
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  2. cookiemonster

    test tone

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    cookiemonster,

    Have a look in Yellow Pages - under motor factors - for your local Partco (Unipart). There they should sell Bodyline Body Damping Pads. Unlike usual alternatives these are not foil backed - which I prefer just in case they come unstuck (which i've never experienced BTW). They work real easy, and best of all cost about £15 for a pack of 10 pads, each being 50cm x 20cm.
     
    test tone, Jul 6, 2003
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  3. cookiemonster

    wadia-miester Mighty Rearranger

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    Test Tone, you will need to be carefull with those car body pads as they usually have some form of Bitchem compond in them, and depending where you place them, I would be cautious
    Dynamat 'Normal or lite' is not as cheap at £10 for a 1m by .5m rool? I think, is far easy to work with and has superior damping qualities, the roll was enough to throughly damp the whole internal case of the Big Belcanto, with enough left to do the Monacrhy upsampler as well.
    There is a 'Extreme' version, but that is £25@ roll.
    Also consider the 'floor of the component', if you have the time and pentients, a 3mm (or thicker) copper plate would help no end.
    Just one other thing, becareful not to place sheets over ventalation slots and holes, heat is a big killer of electronics
    WM
     
    Last edited by a moderator: Jul 6, 2003
    wadia-miester, Jul 6, 2003
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  4. cookiemonster

    cookiemonster

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    Thanks test tone - there is a Unipart local to me - so thanks for the info - something i had not considered.

    Dynamat seems to be the accepted stuff to use - but i welcome further suggestions as to what is available and has worked successfully.

    For those who are interested in the techie bits, and were previously unfamiliar like myself, i have just dug this info up on Dynamat:

    Dynamat Original

    Dynamat Original is a styrene-butyadine-rubber-based, pressure-sensitive adhesive-backed, heat bondable vibrational damper. Dynamat Original conforms and fuses easily to sheet metal and other hard substrates. Material performance is optimized for temperature ranges between 14°F and 86°F (-10°C to +30°C). Material can withstand temperature extremes between -22°F and +350°F (-30°C to +177°C) and is highly resistant to aging.

    The acoustic loss factor "n" is used as a measure of a material's ability to damp structure-borne sound by stating how much vibrational energy (in steel sheets for instance) is converted to heat rather than sound. For constructions containing several layers of damping material, the combined loss factor "n comb" is used. The theoretical maximum loss factor is 1 (no vibration). An undamped 1mm thick steel panel has a loss factor of roughly 0.001 at 200 Hz. Dynamat Original applied to that panel would increase the loss factor to 0.14 @ +50°F (+10°C). Multiple layers of Dynamat Original improve sound damping even more.

    Dynamat Extreme

    Dynamat Xtreme is a patented, lightweight elastomeric butyl and aluminum constrained-layer vibrational damper. Dynamat Xtreme conforms and fuses easily to sheet metal and other hard substrates. Material performance is optimized for temperature ranges between 14°F and 140°F (-10°C to +60°C). Material can withstand temperature extremes between -65°F and +300°F (-54°C to +149°C) and is highly resistant to aging.

    An undamped 1mm thick steel panel has a loss factor of roughly 0.001 at 200 Hz. Dynamat Xtreme applied to that panel would increase the loss factor to 0.417 @ +20°C (+68°F). Multiple layers of Dynamat Xtreme improve sound damping even more.


    I've only looked briefly so far but i have found Dynamat Original for £14.99 for a Sheet - 45.7 x 81.2cm and the Extreme at £24.99 for the same size sheet. This seems reasonable money, and unless some better suggestions come up, i am quite tempted by the Dynamat, and will probably get the Extreme, as it is not that much more expensive and seems to offer (at least according to the theory) much better results.

    cheers

    the copper thing is probably a bit tricky for my uinqualified hands, but something to look at in the future. Hopefully the damping is a decent first mod, and cheap too. Will just do the cdp first.
     
    cookiemonster, Jul 6, 2003
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  5. cookiemonster

    wadia-miester Mighty Rearranger

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    CM, the net is wonderful thing, I put up 2 choices, as in the past I've been accused of 'the dearer option' :eek: extreme is superior and has a foil backing, but is harder to fit (A heatgun simplifies matters no end), also bear in mind possible RF problems with the foil version, maybe a drain wire from the foil to the case earth ;)
    The Dynamt lite, I can supply a phone number for £10@roll purchases (Not ourselves either) PM Me hope that helps
    WM
     
    wadia-miester, Jul 6, 2003
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  6. cookiemonster

    themadhippy seen it done it smokin it

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    wots wrong with the gh favorite BLUE TAC
     
    themadhippy, Jul 6, 2003
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  7. cookiemonster

    GrahamN

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    Any ideas whether this Dynamat or something similar would help suggress some lo-level hum I'm getting off my amp's toroidal transformers? It's sufficiently low-level that I don't notice it if the music is at normal levels (or if the PC is on around the corner), but is just loud enough to be irritating in very quiet stuff (which I play far more often than my reputation - entirely undeserved ;) :shame: - would lead you to believe). I'd probably put some between the trannies and the baseplate, and maybe on top of them too (there looks as if there's something like that there already, and an ali plate to hold each of the trannies in place), and probably a sheet on the top plate too.

    I guess I would need the extreme stuff, as the case can get quite hot - hot enough you really don't want to hold your hand on it for long, so I would guess 60C or thereabouts. Would the glue be OK at these temperatures?
     
    Last edited by a moderator: Jul 7, 2003
    GrahamN, Jul 7, 2003
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  8. cookiemonster

    test tone

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    wadia-miester,

    You're quite right, the bodyline product does have a bituminous base (or some very similar hydrocarbon). Although several such products are similarly based. And, in an automotive environment, the base is of little consequence save the argument of this (mass-loading) type of treatment versus the viscoelasticity of products such as Dynamat Extreme.

    The Extreme BTW is without doubt the best commercially available damping product. But, this is when considering the pressurization of a vehicle cabin with extreme levels of sub-bass generated SPL. In the context of damping hifi casework it is overkill. Although that doesn't mean it can't be used.

    The only reservations i'd have would be in high power amplifiers, or those which run hot through design. That said, the bodyline product takes a fearsome level of heat to even begin to deform, and only breaks down under constant direct heat (yes, i've tried it!).
     
    test tone, Jul 7, 2003
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  9. cookiemonster

    wadia-miester Mighty Rearranger

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    Test Tone, I may have fitted just one or 2 'substanical' in car set ups in my time, and just the odd 'acre' of Dynamat. so that's why I favour it so much.
    The Lite is more than adequate for the vast majority of kit, I have a large power amp, but it's a very cool runner Being Class 'T' so heat is of no concequence to me unlike a lot of other Big power amps, like the Pass X series or older bigger M/F's.
    Graham, you could make a Faraday cadge to encompass the trannys and 'dampt the back of it' just a though.WM
     
    wadia-miester, Jul 7, 2003
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  10. cookiemonster

    GrahamN

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    I should have made it clear - the hum is purely mechanical, with (virtually) nothing through the speakers. So the Faraday cage would not help here, right?
     
    GrahamN, Jul 7, 2003
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  11. cookiemonster

    MO! MOnkey`ead!

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    I used bread roll from maplin but can't find it on the site now. Maybe someone else will have the product number?

    This stuff is sticky! Very!

    Also, it's amazing how far 10 packs of blue tac will go :)
     
    MO!, Jul 7, 2003
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  12. cookiemonster

    timpy Snake Oil free!!!

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    Hi GrahamN

    No screening won't help with mechanical hum from the torroidal transformers. The hum you get will be the turns of the coil vibrating. Often though, this is caused by noice on the mains itself rather than an inherent fault in the tranasformer. Certian mains borne "rubbish" excites some transformers more than others.

    Having seen a piccy of it, have you tried putting the lid back on to try and minimise the distrbance..... ;)

    Other than that you're down to mains conditioning. If you already have (very good) conditioning, it could be that the tranformers are not wound as well / tightly / damped etc. as they might have been when they were made. If that's the case and it's a problem I think re-placement is the answer unfortunately. They may be something you can do with it though, hopefully someone with more experience will be along.....

    Cheers
     
    timpy, Jul 7, 2003
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  13. cookiemonster

    themadhippy seen it done it smokin it

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    you could try tightening/loosening the mounting nut on the tranny.o and if do try damping sure the damping material aint got any metal in, else you could end up making a single turn secondry winding
     
    themadhippy, Jul 7, 2003
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  14. cookiemonster

    cookiemonster

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    I hunted through Maplins before , but can't find it - they only seem to have a couple of more expensive products for this purpose.

    10 packs of blu tack would probably cost the same as the dynamat and is more messy. How would blu tack cope with the temperature transients in a 'hot' amp - plus it is water based isn't it?
     
    cookiemonster, Jul 7, 2003
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  15. cookiemonster

    timpy Snake Oil free!!!

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    Hippy wrote:

    ....been there.....it's expensive in fuses until you realise what you've done :banghead:.....

    The Cambridge Audio amp we had here managed the same trick all on it's own without any intervention from me though, bless it :rolleyes:

    Cheers
     
    timpy, Jul 7, 2003
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  16. cookiemonster

    GrahamN

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    My thoughts were along the line of decoupling the trannies from the case so the latter could not act as a secondary resonator - and the damping acting as sound insulation for the lid. Mains already conditioned through the Trichord, so I doubt there's much more to do there. The trannies are already covered in a layer of translucent plastic electrical insulation - so the windings look pretty safe.

    IIRC Blutack should not be used if the component gets at all hot - FW did and ended up trying to extract a closely bonded layer off the insides of his amp(?).
     
    GrahamN, Jul 7, 2003
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  17. cookiemonster

    MO! MOnkey`ead!

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    I used the blu tack on the bottom of the casing of my DVD come CD transport, (which doesn't get too hot). The base was flimsy and covered with lumps and bumps. I filled them up and spread MOver all over the rest of the base. Make sure you don't cover any holes! The pcbs were loosely held in place by a couple of clips. These weren't doing much at all to secure them. So, I fixed them in the blue stuff too. Making sure that the circuit itself didn't come into contact with the blu tac.

    Then cover the top part of the casing (and the back and front where possible) making sure to leave gaps enabling reasemble. If you do use brown bread, or something similar, it's probably use a knife with disposable blade to cut it. I tried using scissors but ended up with black gluey and extremely sticky stuff on them which took forever to get off. By forever I mean it's still on them!

    Also, it may or may not be required on your casing but, how are the "feet"? Mine were hollow bits of plastic held on with one screw and no washers. I filled them up with silicone gell stuff before putting them back on.

    One thing, I got some weird looks buying 10 packs of blu tack! Think the woman in my local asda thought I was making a blu tack woman! No point trying to explain "oh, it's ok, I'm just going to fill up my hifi with it" Just go for the "art project" story ;)
     
    MO!, Jul 7, 2003
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  18. cookiemonster

    zanash

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    If the traansformer is a square one you can with an insulated screw driver find the vibrating plate , but carefully and I mean carefully inserting the tip between the plate/touching the laminates. Once found, copious amounts of supper glue, three spots not the normal one, between the plate, unplug the unit keep the pressure on the plate to keep them closed. A manufacture of mid ranging amps from the early 90's [Denon?]had this problem with a run of models and this was the dealer fix to solve the hum. My local dealer, did them before he sold them rather than wait for the customer to return them.
     
    zanash, Jul 8, 2003
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