MoJ Posted July 25, 2007 Share Posted July 25, 2007 Hi, I just wanted to check something for my own benefit. I understand ohmage in terms of matching cabs to heads etc (ie 2 x 8 ohms = 4, 2 x 4 ohms = 2 etc), but I wanted to make sure that running an 8 ohm cab with a 4 ohm cab won't be a problem (so long as the minimum rating is 2 ohms from the head, which mine is). The way I see it is that would equal someting between 4 and 2 ohms, without knowing any specific equations for this sort of thing. I stand ready with flame retardant material and gun above my foot (to shoot it with).... Andy Quote Link to comment Share on other sites More sharing options...
Bloodaxe Posted July 25, 2007 Share Posted July 25, 2007 Assuming they're in parallel, it'll be 2.666 recurring. The formula for parallel resistances is 1/R total = 1/R1 + 1/R2 + 1/R3 + ... + 1/Rn Pete. Quote Link to comment Share on other sites More sharing options...
obbm Posted July 25, 2007 Share Posted July 25, 2007 The head may well be able to work down to 2-ohms however it will generate a lot more heat. Another thing you might want to condiser is that the 4-ohm cab will probably be louder than the 8-ohm and tend to dominate. Much better to have two cabs of the same impedance and the same spl/watt if you can manage it. Quote Link to comment Share on other sites More sharing options...
rodl2005 Posted July 25, 2007 Share Posted July 25, 2007 Exactly as OBBM said.... the 4ohm cab WILL get like 2 x the power of the 8ohm cab. Will work, Ive only done it with an ALL TUBE amp that was OK at 4 or 2 ohms & ran it on 2 ohm setting-as it equalled 2.67ohms. Quote Link to comment Share on other sites More sharing options...
MoJ Posted July 25, 2007 Author Share Posted July 25, 2007 Cheers guy. Thought it would work but I hadn't even considered the fact the 4 ohm cab would get more volume. Least I know in theory it works. Anyone know of any 4 ohm 2 x 10's? Andy Quote Link to comment Share on other sites More sharing options...
backwater Posted July 25, 2007 Share Posted July 25, 2007 [quote name='MoJ' post='36741' date='Jul 25 2007, 09:55 AM']Cheers guy. Thought it would work but I hadn't even considered the fact the 4 ohm cab would get more volume. Least I know in theory it works. Anyone know of any 4 ohm 2 x 10's? Andy[/quote] Yamaha used to make a 4ohm 2x10 - the BBT210s. 2x10 + horn, 250w, weighs 21kg. I bought 2 yesterday to use with my superfly and they sounded pretty good - I compared them with an Ashdown Mag 210 and they sounded good. I got mine from Sound Control and Rose Morris show them on their website : [url="http://www.proaudiostore.co.uk/proddet.php?id=3173"]Rose Morris Yamaha BBT210S[/url] Andy Quote Link to comment Share on other sites More sharing options...
bass_ferret Posted July 25, 2007 Share Posted July 25, 2007 You should be able to pick up 4ohm Peavey 2x10s - there are normally some for sale here. AT the other extreme there is an EBS 2x10 going as well. Quote Link to comment Share on other sites More sharing options...
MoJ Posted July 25, 2007 Author Share Posted July 25, 2007 Thanks for the help guys, though Im not persuing my original action now. Basically Id seen an old Trace Elliot 1524 (2 x 15 4 ohm rating) which is pretty much what I really want and although the sale hadnt met the reserve and I wasnt the highest bidder the guy was prepared to offer it to me. I just wanted a light weight (compared to my 4 x 10 at least) option for the high end part of my tone whcih would also been closer to my ears fom stacking, I just needed to confirm I could do it despite the odd impedance the two cabs would create. I didnt know of anyone making 4 ohm 2 x 10s. Just found out the cost of some repair work to my car so today and I doubt Ill be buying anything in the near future Pains me to miss up a great oppurtunity. Guess Ill just have to wait for some money, and Bill Fitzmaurice to release plans for the O15 Tallboy and have myself a self build Andy Quote Link to comment Share on other sites More sharing options...
alexclaber Posted July 25, 2007 Share Posted July 25, 2007 I cannot imagine any 4x10" being heavy enough to make a TE 2x15" appear light in comparison! Alex Quote Link to comment Share on other sites More sharing options...
MoJ Posted July 25, 2007 Author Share Posted July 25, 2007 (edited) [quote name='alexclaber' post='36962' date='Jul 25 2007, 06:15 PM']I cannot imagine any 4x10" being heavy enough to make a TE 2x15" appear light in comparison! Alex[/quote] Have you tried picking up a [url="http://peavey.com/products/browse.cfm/action/detail/item/116527/number/00584650/cat/14/begin/1/TVX+410+EX%3F+4+ohm.cfm"]Peavey TVX 4 x 10[/url]? Im assuming that weight is in lbs, which means it's about 30 lbs heavier (apparantly 30 bags of sugar!!) than my Trace 4 x 10. I borrowed one to try out my current head. Never again, though it was a great sound. A 2 x 10 would make a rig comprising of a 2 x 15 lighter still. The new TE 1528 is 77 lbs so is comparable. I wouldnt know if they've changed the construction though, thus making it lighter but I do note its 8 ohms not 4, and about £400 more than I was going to have pay, including shipping for the 1524. Damn, I [i]knew[/i] I was going to regret declining it. Really hope the plans for the O15 Tallboy come soon! Alex, I need to ask you about the crossover built in to BFM designs like the O15, as being passive I understand that they will only handle a certain amount of wattage. Does that mean it has to be built super big? My Peavey Pro is 350w at 4 ohms (I assume the O15 is designed to be 4 ohms?). Is it just easier to wait for the plans, and wouldn't you be able to do a version, being as its your creation n all Andy Edited July 25, 2007 by MoJ Quote Link to comment Share on other sites More sharing options...
alexclaber Posted July 25, 2007 Share Posted July 25, 2007 [quote name='MoJ' post='37005' date='Jul 25 2007, 08:32 PM']The new TE 1528 is 77 lbs so is comparable.[/quote] Ah, the old TE cabs were made of MDF and weighed a ton, easily as much as a 410TVX [quote name='MoJ' post='37005' date='Jul 25 2007, 08:32 PM']Is it just easier to wait for the plans[/quote] Definitely! All I did was bodge Bill's sketchup model into a new arrangement to illustrate my idea. The series inductor in the woofer lowpass filter needs to be pretty heavy gauge - like this: [url="http://www.partsexpress.com/pe/pshowdetl.cfm?&PartNumber=255-116"]http://www.partsexpress.com/pe/pshowdetl.c...tNumber=255-116[/url] Alex Quote Link to comment Share on other sites More sharing options...
MoJ Posted July 25, 2007 Author Share Posted July 25, 2007 [quote name='alexclaber' post='37017' date='Jul 25 2007, 09:25 PM']Ah, the old TE cabs were made of MDF and weighed a ton, easily as much as a 410TVX[/quote] Then Im not surprised they were heavy! I was surprised after hearing about old TE stuff being heavy that the new 4 x 10 isn that bad. [quote name='alexclaber' post='37017' date='Jul 25 2007, 09:25 PM']Definitely! All I did was bodge Bill's sketchup model into a new arrangement to illustrate my idea. The series inductor in the woofer lowpass filter needs to be pretty heavy gauge - like this: [url="http://www.partsexpress.com/pe/pshowdetl.cfm?&PartNumber=255-116"]http://www.partsexpress.com/pe/pshowdetl.c...tNumber=255-116[/url] Alex[/quote] Fair enough. Ill just wait it out for Bill's plans. Reeeally hope it doesnt take too long. Thanks Alex Andy Quote Link to comment Share on other sites More sharing options...
Bloodaxe Posted July 25, 2007 Share Posted July 25, 2007 [quote name='MoJ' post='36947' date='Jul 25 2007, 05:29 PM']Bill Fitzmaurice to release plans for the O15 Tallboy and have myself a self build Andy[/quote] Tallboy? [url="http://www.lancastermuseum.ca/s,tallboy.html"]eep.[/url] Will it be followed up with a Grand Slam? [url="http://www.raf.mod.uk/bombercommand/grandslam.html"](bigger eep)[/url] Quote Link to comment Share on other sites More sharing options...
MoJ Posted July 25, 2007 Author Share Posted July 25, 2007 [quote name='Bloodaxe' post='37039' date='Jul 25 2007, 10:10 PM']Tallboy? [url="http://www.lancastermuseum.ca/s,tallboy.html"]eep.[/url] Will it be followed up with a Grand Slam? [url="http://www.raf.mod.uk/bombercommand/grandslam.html"](bigger eep)[/url][/quote] I can only hope, looking at the spl charts for the standard O15 that the modded cab is the sonic equivalent! Andy Quote Link to comment Share on other sites More sharing options...
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