LITTLEWING Posted December 28, 2014 Share Posted December 28, 2014 Does anyone find sound deadening inside bass cabs good or bad? I use a Fender Rumble 100 with a 15" speaker in our rehearsal space (disconnected the tweeter-yuk!!) and the stupid red Leds. (yuk again!!). Anyhow, its always sounded great up to about half volume and then after that begins to sound too harsh as though the bass is 'fighting' itself. The cab isn't exactly very deep so could the waves be reflecting off the back too much? I was thinking about damping the inside just on the back with something or other to possibly 'tame' the middle boom. Quote Link to comment Share on other sites More sharing options...
discreet Posted December 28, 2014 Share Posted December 28, 2014 (edited) [quote name='LITTLEWING' timestamp='1419806964' post='2642923'] I was thinking about damping the inside just on the back with something or other to possibly 'tame' the middle boom. [/quote] It can't hurt to give it a go. Damping is important, but a lot of mass-produced cabs don't have it - for the usual reason. You could try a bit of backed carpet or if there's room, some cotton wadding. Stick it with some spray adhesive. Edited December 28, 2014 by discreet Quote Link to comment Share on other sites More sharing options...
Bill Fitzmaurice Posted December 28, 2014 Share Posted December 28, 2014 An undamped cab is a defective cab. There's no justification for any manufacturer saving two or three quid by not using damping, other than that they just don't give a flying f..k how it sounds, and telling the consumer "if you want a better amp, spend more money". But as for damping taming midbass boom, it won't. Midbass boom is caused by inexpensive drivers and/or a cab that's too small for them. Quote Link to comment Share on other sites More sharing options...
discreet Posted December 28, 2014 Share Posted December 28, 2014 [quote name='Bill Fitzmaurice' timestamp='1419809162' post='2642949'] Midbass boom is caused by inexpensive drivers and/or a cab that's too small for them. [/quote] Probably a bit of both in this case. Quote Link to comment Share on other sites More sharing options...
LITTLEWING Posted December 29, 2014 Author Share Posted December 29, 2014 Cheers, chaps. Happy New Year. Quote Link to comment Share on other sites More sharing options...
stevemaiden Posted December 31, 2014 Share Posted December 31, 2014 I've found foam packing an excellent damping for cabs - my son's work has lots of surplus packing foam from computer components boxes & some come in useful sizes. I attach it with spray adhesive (£4.99 @ B&Q) & find the black "egg box" shape particularly effective (installed in TE 4x10 & Roland bass combo). HNY! Quote Link to comment Share on other sites More sharing options...
Moos3h Posted December 31, 2014 Share Posted December 31, 2014 There's a good chance it's Donald. I've used those before and with the shape button in and a touch of bass cut, they've sounded fab right up to VERY loud volumes. All amps lose it a bit when they have the nuts revved off them... Quote Link to comment Share on other sites More sharing options...
taunton-hobbit Posted December 31, 2014 Share Posted December 31, 2014 Old-fashioned carpet felt underlay is very good, if you can get hold of it........... 1 Quote Link to comment Share on other sites More sharing options...
discreet Posted December 31, 2014 Share Posted December 31, 2014 ARIBA, ARIBA!! UNDERLAY, UNDERLAY!! Quote Link to comment Share on other sites More sharing options...
Dan Dare Posted January 3, 2015 Share Posted January 3, 2015 It ain't cheap, but proper contoured acoustic foam is best. Be careful with spray adhesives. The fumes can harm drive units. I use Unibond. Quote Link to comment Share on other sites More sharing options...
Bill Fitzmaurice Posted January 3, 2015 Share Posted January 3, 2015 [quote name='Dan Dare' timestamp='1420291390' post='2647566'] It ain't cheap, but proper contoured acoustic foam is best. [/quote]Actually, it isn't. The main benefit of the contouring of acoustic foam is visual. It looks like it should work better than plain foam, but it doesn't. Compared to an equal thickness of plain foam acoustical foam is a lot less foam, a lot more air, and air has no damping properties. The reason acoustical foam is made that way is to make it resemble diffraction grids, which serve a totally different purpose than damping foam. It's often called 'eggcrate foam', and in fact decades ago recording studios really were lined with pulp eggcrates. It's often assumed their purpose was damping or soundproofing, but their actual function was to scatter reflected waves. That's not what one wants to do inside a speaker enclosure. When the change was made in studios from low tech egg crates to high tech foam the shape of the crates was retained, but not the function, as foam doesn't scatter reflected waves the way that solid pulp does. Quote Link to comment Share on other sites More sharing options...
taunton-hobbit Posted January 3, 2015 Share Posted January 3, 2015 That'll be back to carpet felt underlay then............. Quote Link to comment Share on other sites More sharing options...
discreet Posted January 3, 2015 Share Posted January 3, 2015 [quote name='taunton-hobbit' timestamp='1420294424' post='2647651'] That'll be back to carpet felt underlay then... [/quote] [quote name='discreet' timestamp='1420061718' post='2645348'] ARIBA, ARIBA!! UNDERLAY, UNDERLAY!! [/quote] Quote Link to comment Share on other sites More sharing options...
Bill Fitzmaurice Posted January 3, 2015 Share Posted January 3, 2015 [quote name='taunton-hobbit' timestamp='1420294424' post='2647651'] That'll be back to carpet felt underlay then............. [/quote]Felt underlay works well. On this side of the pond you can't find all you want for free if you're not adverse to dumpster diving for scraps at a carpet store. Quote Link to comment Share on other sites More sharing options...
Dan Dare Posted January 3, 2015 Share Posted January 3, 2015 Bill. Not entirely. The purpose of a contoured surface is not only/simply to scatter reflected waves. It has absorptive properties, too. A flat sheet of solid foam (especially hard foam) will, at least in part, reflect sound waves back at the cone - just the situation one is attempting to avoid. In practice, effectiveness is limited by wavelengths. Foam lining is less effective on lower frequencies. Quote Link to comment Share on other sites More sharing options...
Kiwi Posted January 3, 2015 Share Posted January 3, 2015 Quote Link to comment Share on other sites More sharing options...
paul_5 Posted January 3, 2015 Share Posted January 3, 2015 I used some candy floss / cotton wool type stuff that was originally packing from something or other at work inside my home-made 1x12" cab. I stapled it to the frame of the cab that houses a 50W no name driver (from a Harley Benton guitar amp, I believe) with a small port in the front. Perfectly adequate for playing at home and turns out it's AWESOME as a guitar cab... I think it cost me £20 in total. Don't get me wrong, it's never going to compete with a Barefaced / TKS unit, but it does what I need it to. Quote Link to comment Share on other sites More sharing options...
Bill Fitzmaurice Posted January 3, 2015 Share Posted January 3, 2015 [quote name='Dan Dare' timestamp='1420317810' post='2648083'] A flat sheet of solid foam (especially hard foam) will, at least in part, reflect sound waves back at the cone [/quote]True, hard foam will do so. Acoustical foam isn't hard. Acoustical foam does have reflective properties where the wavelengths are short compared to the solid bits of the material that make up the foam matrix, but those wavelengths are far shorter than those produced by woofers. Even at 4kHz a wavelength is better than 3 inches/85mm. Quote Link to comment Share on other sites More sharing options...
Dan Dare Posted January 3, 2015 Share Posted January 3, 2015 Looking at the original question, I wonder if amp clipping may be to blame. Most combos will struggle once the master volume goes over the half way mark. Quote Link to comment Share on other sites More sharing options...
Bill Fitzmaurice Posted January 3, 2015 Share Posted January 3, 2015 [quote name='Dan Dare' timestamp='1420322324' post='2648147'] Looking at the original question, I wonder if amp clipping may be to blame. Most combos will struggle once the master volume goes over the half way mark. [/quote]Perhaps, but it's a crapshoot with combos which will run out first, the amp headroom or the driver xmax. It's not unusual for combo drivers to run out of excursion capability with even 40 watts input. Quote Link to comment Share on other sites More sharing options...
Dan Dare Posted January 4, 2015 Share Posted January 4, 2015 True. Could well be both. Quote Link to comment Share on other sites More sharing options...
LITTLEWING Posted January 7, 2015 Author Share Posted January 7, 2015 (edited) Just a quick update, I took the speaker out and found a large lump of 40 x 40cm wood pinned diagonally across the back panel which looks like there were vibration problems with the cabinet at some point, so as an experiment I screwed a fairly large piece of hard foam to it effectively raising it off the rear panel aiming to kill some box-ey sound waves. Slap me hard and call me Doris, but it actually sounds like a bloody good quality combo now. Used it yesterday at praccy and I was smilng like a dog with two wotsits. No more bare wood cabs for me in the future. (Notes to Rumble 100 owners - 1/ disconnect completely unnecessary tweeter, 2/ disconnect completely unnecessary red led's, 3/ fix a lump of foam to rear internal panel, 4/ snip the spade connectors off the speaker wires and SOLDER them on. (You will now have a sensible combo). Edited January 10, 2015 by LITTLEWING Quote Link to comment Share on other sites More sharing options...
taunton-hobbit Posted January 8, 2015 Share Posted January 8, 2015 (edited) A few years back, I had some 15" Tannoy Golds in 2'x2' x 1' Chipboard boxes - the backs simply screwed on, and I landed up fitting them with carpet felt, and a ruddy great 4x2 brace across the middle, the back being screwed to it in three places - used them for about ten years with no issues (apart from the pathetically low wattage handling)....sounded nice, though...... vvvv I bought six at 45 quid each, they'd come from the Blind Beggar pub (Google Kray Brothers) in 1977(ish) - I used them fairly solidly until the mid 80's and sold them, out of the cabinets to a bloke that was exporting UK kit to Japan. I think he paid me a thousand quid for all of them (with crossovers), so I was a happy bunny.....they seem to be about 1k each now, but it's been thirty years......I also sold him a Quad preamp & two amps along with a Thorens deck - I think he gave me 1500 in total (sigh)..... Edited January 10, 2015 by taunton-hobbit Quote Link to comment Share on other sites More sharing options...
Dan Dare Posted January 10, 2015 Share Posted January 10, 2015 Wow. Bet they did sound nice. Have you seen how much 15" Tannoy Golds go for these days? Quote Link to comment Share on other sites More sharing options...
JPJ Posted January 23, 2015 Share Posted January 23, 2015 I recently picked up a secondhand TC Electronics BG500 combo off this here forum. I was initially very impressed with this combo (see my other thread) but the more I got to know the amp, the less I liked the sound coming out of the cabinet. To describe my issues, firstly, it didn't matter how I adjusted the tone controls, I couldn't get rid of that hard edgy mid range sound that really didn't suit my style of playing at all. Secondly, minor tweaks of the tone controls had huge impact on the tone and the overall volume. So today, remembering this thread, I decided to whip the speakers out and have a look inside to see whether there was any damping material in there. Surprise surprise, when I got the speakers out, I found myself staring into a big empty mdf box with not a shred of damping material anywhere. Having some left over from an earlier project, I set to with the scissors and staple gun covering the back, sides, top and the top of the shelf port. Having reinstalled the speakers and refitted the sturdy grill, I fired up the combo and WOW what a massive difference. The response of the cab is much deeper sounding and very 'natural' with no harshness or brittleness to the tone whatsoever. The difference is so huge I initially thought I must have dialled up the bass control by accident. Then I got to thinking, this combo wasn't cheap when it was originally purchased, yet a respectable brand like TC Electronics hadn't taken the time to fit 50p's worth of acoustic damping in the cabinet. I hope they were a little more careful with their flagship RS cabs. Quote Link to comment Share on other sites More sharing options...
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