I have a pair of old Leak 3080s with lovely cabinets; I'm doing a re-drivering of them as re-building the original drivers are into arm anna leg territory, even if I could find someone to do them. Mids have been done and sound ok with the original x-overs. I have a nice set of 10" bass units but they're 4ohm, which the x-over isn't expecting, and doesn't like. Been racking my brains trying to figure out wtf I could use for an impedence matching txfrmr - there so much electrical junk scattered around these days I'm fairly sure I could salvage and re-purpose something to give me a 200/140 match in turns. Their the figures I got from a site - if I get something near I can strip wire off until it's right.
In general the bass part will be a series choke and a capacitor across the bass unit.
Half the choke inductance..but removing turns or winding with fewer turns of thicker, and double up the capacitor. I think its half the turns and double the capacitor for the same crossover frequency adjusted to half the original impedance and the same LF response.
Its far harder to mess with the HF units/crossover
If the bass power has gone up a bit..well a +3dB ripple in the bass won't be so bad.
Chances are there is some volume reduction in the midrange/tweeter. That you can take out..
going to get nearly as good a result as the original setup.
Yes, it's on a cusp of practicality vs cost.
what problem you're running into that you can't solve.
Again, as above. I'm doing this as cheaply as practically possible, whilst retaining some degree of audio fidelity and using what I have available. The cabs and x-overs are a major part of this and original (the x-overs were re-capped a few years ago and still work ok). I was hoping to get away with just re-foaming the edges of the mids, but the weird non-standard size meant a special order and extra cost. That's when I decided to just use something off the shelf and it sounded ok. Then I discovered the bass units were fubared - one was falling apart and the other one was seized solid. They've suffered from being in damp storage for years. Ironically, the bass edges were rubber-surrounded and the rubber has survived fine, unlike the original mids. Since this would be the first time I've rebuilt drivers from scratch, I don't want to spend money on fubaring it up and then have to spend on replacements anyway. The original cones are now quite brittle, and won't take much handling, and one is damaged/repaired already. That's money down the drain. Far cheaper to use what I have or simply fit a pair of cheap-ish bass drivers.
I'm not looking to achieve audiophile quality - just home theatre use with a decent degree of volume and clarity. Even with the cheap mids and 4ohm 10" units in place the difference between the ordinary Aiwa and Jamo boxes and these 3080s is very noticeable indeed, and that's with age-related hearing loss, too (which probably works in my favour, not being able to hear the mismatches :) )
I don't really give a shit - they still sound good to me - they always did.
Anyway, to sum it up - twenty years ago, when I first enquired, Wharfedale were quite willing to rebuild all the units at a cost of 40 to 50 quid each for the mids and 60 to 70 quid each for bass - plus P&P. Stuff that - while it would be nice to have them all rebuilt and original, it's hardly worthwhile now, even if there was someone willing to do it.
not going to get nearly as good a result as the original setup.
ing what problem you're running into that you can't solve.
Foam rubber strip is only a few quid a roll last time I looked. EPDM lasts = well.
its usually cheaper to buy new cones. Last time I looked they were 10-15 a = time, depending mainly on size. If you can get cones of the same weight & m= aterial, so much the better, and if you can get original mfr spec ones, per= fect. Rewinding them's quite simple if you've got an original one to measur= e the copper diameter on and count the turns. Don't ever let the new wire t= ake up more of the voice coil length, or it goes nonlinear. IIRC, and it wa= s a while ago, a high temp epoxy in minute amounts does a good job of fixin= g the wire down.=20
Braid should be reusable, but if you need new, any small copper braid will = do the job.
If you dont GAS, as suggested just halving the crossover L and doubling the= C if there is one would get the 4ohm units working ok. If your amp will do= 4 ohms, great, if not you get a lot less power out before it overheats and= cuts out if modern, or dies if a bit older.
If you use a transformer, you could just remove part of one side of the sec= ondary winding to get the right ratio autotransformer. So eg a 12-0-12 woul= d become a 12-0-5. Remove the primary to avoid arcing.
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