Members Dark Ice Posted January 13, 2009 Members Share Posted January 13, 2009 Hey folks, hoping you might indulge me a bit here. Not posting this on the guitar forum because I know a lot of you guys are very knowlegable about speaker design. I've been reading about the isobarik configuration and, from what I can tell, the characteristics are reduced sensitivity and less cabinet space needed. I also read that they dont need to be in a clamshell formation. It seems to me that these characteristics would be excellent for a guitar speaker, the reduced sensitivity (3dB less efficient according to winISD) would let you drive the tubes harder/at less volume, and the less weight/bulk the better, right? I havn't been able to find much actual in depth information (ie, WHY does this configuration have these characteristics?) about the design however, so I need to ask those who do know - is it as simple as I describe? I dont see any products on the market like this so I doubt it is Another question for you carpenters, would this be a viable project for someone who has NO woodworking skills but a desire to learn new things? Cheers HC. Steve. Link to comment Share on other sites More sharing options...
Members dboomer Posted January 13, 2009 Members Share Posted January 13, 2009 There's lots of ways to reduce sensitivity. Isobarik cabs are about getting low bass (well below what you need for guitar) in a smaller cabinet size. A 3 dB reduction is not much at all (as in barely noticeable). What do you want to do? Link to comment Share on other sites More sharing options...
Members preacherman672 Posted January 13, 2009 Members Share Posted January 13, 2009 For a modern bass heavy guitar sound it might work. Cone breakup is a major part of guitar sound though and I don't know how that would work with the isobarik configuration. If you are using a modeler it would probably be a better option. If you've never done any woodworking a basic front loaded ported or sealed cab would probably be a better starting point. Still shouldn't be a difficult build. Link to comment Share on other sites More sharing options...
Members moody Posted January 13, 2009 Members Share Posted January 13, 2009 Maybe if you wanted to run a couple of really small speakers, like 2 x 8" for your guitar it could work. The extra bass extension would make up for the lack of low end on the small speakers. Or you can just get a single 12" speaker that sounds right for you. If you need more break up at lower volume then the cheapest good way to do it is to get a high quality small valve amp. 5 watts is currently very popular. Link to comment Share on other sites More sharing options...
CMS Author Craig Vecchione Posted January 13, 2009 CMS Author Share Posted January 13, 2009 There's simply no use for such low extension for a guitar, even drop-tuned. Plus it simply won't sound like a guitar cabinet, which is usually specifically tuned and drivered for midrange. It's really not a good application for this design. Link to comment Share on other sites More sharing options...
Members Dark Ice Posted January 14, 2009 Author Members Share Posted January 14, 2009 Alright, the holes in my knowlege are showing already, great! A lot of you are saying this is going to be a bass-heavy design, and I'm not sure why. I'm not planning on making this a subwoofer, just using standard guitar speakers, sealed from the back. Like I say, I'm not planning on using this in a clamshell formation, since I wouldn't hear the front of the speaker. According to the helpful winISD helpfile, I could mount them like this So...am I missing something here? Please enlighten me, I'm here to learn! What do you want to do? Really, I just want to experiment and try something 'new'. Sure, I could just build it and see what happens but, I'd really like to see if theres any merit in what I'm going to try before I spend any time on this. I'd like to achieve something a bit different and maybe even 'better' than the norm, but I'd be happy if I end up with a decent sounding guitar cab I want to learn. Steve. Link to comment Share on other sites More sharing options...
Members Mogwix Posted January 14, 2009 Members Share Posted January 14, 2009 Really, I just want to experiment and try something 'new'. Sure, I could just build it and see what happens but, I'd really like to see if theres any merit in what I'm going to try before I spend any time on this. I'd like to achieve something a bit different and maybe even 'better' than the norm, but I'd be happy if I end up with a decent sounding guitar cab I want to learn. Honestly, you'd be better off with a lower power speaker and a power brake. A 15w alnico blue and a THD hot plate? SEX! 3dB drop in sensitivity isn't really all that much, so you won't be driving your power tubes that much harder. Power tube drive is great, but for me cone breakup is more important. I use greenbacks for their early breakup, amazing sound. As stated, isobaric designs are popular in car audio sub designs because they have the advantages of a higher power handling (two speakers vs. one) and lower freq response in a smaller cabinet. There's no harm in trying it though, really. It's probably a waste of time, but if you go for a pair of 10" guitar speakers in a small-ish cabinet, that thing will probably have a sound that's not what you're looking for, but will most likely be incredibly useful in some way. Give it a shot, unless you're short on cash... then you should probably be buying your family food anyways. Link to comment Share on other sites More sharing options...
Members preacherman672 Posted January 14, 2009 Members Share Posted January 14, 2009 I say give it a shot if you have the time and the desire. Might come up with something useful and there's an off chance it will be really nice. I would probably go with two smaller speakers and see if you can get some added bass response in a smaller package. Would be worth it that way IMO. Link to comment Share on other sites More sharing options...
Members jasps Posted January 14, 2009 Members Share Posted January 14, 2009 As stated, isobaric designs are popular in car audio sub designs because they have the advantages of a higher power handling (two speakers vs. one) and lower freq response in a smaller cabinet. My understanding of isobaric designs are that the low frequency extension is lower, at the COST of having reduced sensitivity. So, one effectively has to buy a 2x bigger amplifier for the same peak output of a cabinet with one driver with the advantage of lower frequency response in a smaller cab. I'd appreciate any additional clarification. Link to comment Share on other sites More sharing options...
Members Dark Ice Posted January 14, 2009 Author Members Share Posted January 14, 2009 My understanding of isobaric designs are that the low frequency extension is lower, at the COST of having reduced sensitivity. Well...my understanding was that the size of the cabinet was lower(for equivalent tuning) at the cost of lower sensitivity. Both things seem beneficial to me for a guitar cab. In the formation I've selected I read that there are also side effects such as the magnet heating and lower transient response which might make for some interesting audible effects (hey, its not a PA speaker, its not meant to sound hifi). I'd like this cab to be usable with most guitar heads, which is why I'm not going for the low power valve amp idea (although I would love one), and I really cant be assed with more boxes, wires, and knobs to get wrong live so I'm not keen on a powerbrake. Weber say that they use speaker motors so soak power in their attenuators. Is this as simple as it sounds? Ie- could I just rip the cone off a speaker and use it to waste power or as a dummy load? Steve. Link to comment Share on other sites More sharing options...
Members boseengineer Posted January 14, 2009 Members Share Posted January 14, 2009 It seems to me that you are trying to solve a problem that you don't have in the first place. You can make a guitar cab as small as you want it, it will still work fine. Biggest difference in low end response is whether you do and open back or closed back cabinet. Isobaric design isn't trivial. It works best if both drivers work in unison. However, the acoustic load that the rear speaker sees to the rear is different than what the front speakers sees to the front. That means you'll get a fair amount of differntial pressure across the the two drivers. The best way to deal with this it to make the space between two drivers really, really small, which is mechanically tricky. If the air volume is too big it acts as another resonator and you can end up with a really weird frequency response and the drivers can also bump into each other (although that sounds counterintuitive). Your best shot is regular power break, i.e. a dummy load on the amp output. In theory you can use speaker without a cone for this, although I don't see why that would be better than a regular power resistor. When you remove the cone the voice, you change the back EMF (electromagnetical force) to the amp quite a bit. Also since the voice coil wan't move and there is no air movements, it can't take as much heat and the power handling will be significanty less. Link to comment Share on other sites More sharing options...
CMS Author Craig Vecchione Posted January 15, 2009 CMS Author Share Posted January 15, 2009 Well...my understanding was that the size of the cabinet was lower(for equivalent tuning) at the cost of lower sensitivity. Both things seem beneficial to me for a guitar cab. In the formation I've selected I read that there are also side effects such as the magnet heating and lower transient response which might make for some interesting audible effects (hey, its not a PA speaker, its not meant to sound hifi). I'd like this cab to be usable with most guitar heads, which is why I'm not going for the low power valve amp idea (although I would love one), and I really cant be assed with more boxes, wires, and knobs to get wrong live so I'm not keen on a powerbrake. Weber say that they use speaker motors so soak power in their attenuators. Is this as simple as it sounds? Ie- could I just rip the cone off a speaker and use it to waste power or as a dummy load? Steve. Boxes, wires, knobs! Oh my! Don't you have a pedalboard? Link to comment Share on other sites More sharing options...
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