JapanAxe Posted December 13, 2013 Share Posted December 13, 2013 I've just made this. It cost me less than £15 and I carry it in my stand bag. Can you tell what it is, children? Quote Link to comment Share on other sites More sharing options...
lowdowner Posted December 13, 2013 Share Posted December 13, 2013 It's an isolating stand for your cabs What's my prize? Quote Link to comment Share on other sites More sharing options...
Roland Rock Posted December 13, 2013 Share Posted December 13, 2013 (edited) Hmmm, looking at the picture, and your tags "gramma" and "isolation", I can only deduce that, since becoming a grandmother, you've decided to become a hermit and play dominoes for the rest of your life Edited December 13, 2013 by Roland Rock Quote Link to comment Share on other sites More sharing options...
BigRedX Posted December 13, 2013 Share Posted December 13, 2013 You need to fill the gaps between the supports or they could create resonant spaces which would diminish the effectiveness of trying to isolate your cabs from the floor. Quote Link to comment Share on other sites More sharing options...
JapanAxe Posted December 13, 2013 Author Share Posted December 13, 2013 Congratulations lowdowner, your prize is the universal adulation that comes only from Basschat. Yes I was thinking about the plus and minus points of a Gramma Pad: Does the job by all accounts, but bigger than I need, a bit bulky to carry about, and a bit more then I want to spend. I also didn't see the point of the wooden platform part - surely the isolating foam is the important bit? So, I cut 34cm lengths of Platfoam to match the depth of my BF cabs, then measured the positions of both sets of cab feet, and drilled recesses with a 25mm wood bit. The foam tends to pop back up so you have to go a bit deeper, to about half the depth of the foam. This makes the setup more stable as almost all the top of the foam is in contact withe bottom of the cab. I am considering fitting some kind of spacer to align the foam withe the Compact, but in the meantime I intend to try it on a gig tomorrow night, then I should know whether any tweakage is required. Quote Link to comment Share on other sites More sharing options...
JapanAxe Posted December 13, 2013 Author Share Posted December 13, 2013 (edited) [quote name='BigRedX' timestamp='1386962690' post='2306991'] You need to fill the gaps between the supports or they could create resonant spaces which would diminish the effectiveness of trying to isolate your cabs from the floor. [/quote] I did wonder about that but if you Google 'platfoam' you will find pictures on Auralex's website showing the same arrangement being used under a drum riser, and the Platfoam instructions tell you to leave 4-inch gaps between the lengths of foam. The gaps are actually 3.75in when used with the Compact, and 0.5in with the Midget. I reckon the spaces won't resonate because 2 of the 4 walls are made of foam, and too soft to form vibrational nodes. [u]EDIT:[/u] Speed of sound v = 340ms[sup]-1[/sup], distance between cab base and floor (the two hard surfaces) is 0.05m so standing wave would have length λ = 0.1m v= fλ f = v/λ = 340ms[sup]-1[/sup]/0.1m =3400s[sup][size=3]-1[/size][/sup] =3.4kHz Hardly bass boom! Edited December 13, 2013 by JapanAxe Quote Link to comment Share on other sites More sharing options...
BigRedX Posted December 13, 2013 Share Posted December 13, 2013 [quote name='JapanAxe' timestamp='1386963487' post='2307008']Speed of sound v = 340ms[sup]-1[/sup], distance between cab base and floor (the two hard surfaces) is 0.05m so standing wave would have length λ = 0.1m v= fλ f = v/λ = 340ms[sup]-1[/sup]/0.1m =3400s[sup]-1[/sup] =3.4kHz Hardly bass boom! [/quote] = mid-range hump which may or may not be desirable depending on your sound and the sound of the other instruments in the band. The actual Gramma Pad has corrugated foam in the gap between the two foam supports. Quote Link to comment Share on other sites More sharing options...
nottswarwick Posted December 13, 2013 Share Posted December 13, 2013 Could you not just put it on a big piece of the foam, the size of the cab footprint? Quote Link to comment Share on other sites More sharing options...
JapanAxe Posted December 13, 2013 Author Share Posted December 13, 2013 (edited) [quote name='BigRedX' timestamp='1386966199' post='2307052'] = mid-range hump which may or may not be desirable depending on your sound and the sound of the other instruments in the band. The actual Gramma Pad has corrugated foam in the gap between the two foam supports. [/quote] [url="https://dl.dropboxusercontent.com/u/32485154/3400.wav"]3.4kHz[/url] is quite high up in the mid range. For this resonance to occur, the bottom of the Barefaced cab (which has a usable range up to 4kHz) would have to be vibrating at 3.4kHz. I don't think Alex would be very happy if that was happening, what with all that bracing going on! [quote name='nottswarwick' timestamp='1386967185' post='2307067'] Could you not just put it on a big piece of the foam, the size of the cab footprint? [/quote] I did consider that, but I would need one piece for the Compact and another for the Midget. [EDIT - I consider bits sticking out at floor level to be hazardous!] Anyway, here is a picture of the recommended drum riser application from the Auralex website. Note all the gaps: And the application sheet is [url="http://www.auralex.com/sound_isolation_platfoam/PF.pdf"]here[/url]. Edited December 13, 2013 by JapanAxe Quote Link to comment Share on other sites More sharing options...
UglyDog Posted December 14, 2013 Share Posted December 14, 2013 (edited) [quote name='JapanAxe' timestamp='1386971105' post='2307140'] And the application sheet is [url="http://www.auralex.com/sound_isolation_platfoam/PF.pdf"]here[/url]. [/quote] They seem to have had a bit of a Spinal Tap 'Stonehenge' moment with their diagram. "F**K THE NAPKIN!" Edited December 14, 2013 by UglyDog Quote Link to comment Share on other sites More sharing options...
JapanAxe Posted December 15, 2013 Author Share Posted December 15, 2013 Just got back from a gig using my full rig - Streamliner 900, Midget, Compact. The pub had wooden floorboards and there is a lower level at the back, so I am guessing the cellar was underneath us. I don't recall bass boom problems from previous gigs there, but I decided to use the foam anyway. The sound was well behaved, and I am happy to report that I detected no upper-mid-range resonance. Of course the proof of the pudding will be a high wooden stage... Quote Link to comment Share on other sites More sharing options...
bridge Posted December 15, 2013 Share Posted December 15, 2013 (edited) Had my first gig with my Streamliner 900 and compact last night. Large sports type hall with 'sprung' wooden floor. I have not experience/noticed 'boom' before and at first, soundman though it was problem with mics, however having read a lot recently on BC with reference to this problem, I stuck the only thing available underneath the compact, the box from the streamliner!! not perfect, but helped. will looking urgently at making something now, cant afford to pay out £50 Edited December 15, 2013 by bridge Quote Link to comment Share on other sites More sharing options...
JapanAxe Posted December 15, 2013 Author Share Posted December 15, 2013 [quote name='bridge' timestamp='1387105943' post='2308179'] Had my first gig with my Streamliner 900 and compact last night. Large sports type hall with 'sprung' wooden floor. I have not experience/noticed 'boom' before and at first, soundman though it was problem with mics, however having read a lot recently on BC with reference to this problem, I stuck the only thing available underneath the compact, the box from the streamliner!! not perfect, but helped. will looking urgently at making something now, cant afford to pay out £50 [/quote] A single 4ft length of Platfoam like I used is £10.54 + VAT + delivery from Studiospares.com Quote Link to comment Share on other sites More sharing options...
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