Hey guys, I have an old pair of Sony SS U501’s they have a mid range, tweeter and woofer. They look as if they have two woofers, but one is a blank - I put two new woofers in and wired them parallel I did not touch the mid or the tweeter, but I am wondering now should I change the wiring setup for those as well? Seeing I added another woofer, did not know if it would affect the mid and tweeter. These are 8 ohm speakers if that helps.
Those extra "blank" woofers are probably passive radiators, they are that way on purpose and are needed to make the speaker work correctly. I'd put them back if I were you, and try to resist the temptation to swap out anything else.
That 'blank' woofer is called passive radiator. It works almost like bass reflex. Its used when bass reflex is too long.
You just messed up your sony speakers. Put original woofer back if it works.
You just messed up your sony speakers. Put original woofer back if it works.
Lol oh boy! Thanks for the heads up! I guess I’ll keep them, but I do need to replace the rubber around the edges it’s all torn
So these speakers being old, the original passive and woofer have deteriorated. Can I use one of the new woofers as a passive?
you can, but you would have to tune the diaphragm (by adding or eventually removing weight) for the correct resonance frequency.
i suggest you try to exchange the surrounds (probably foam surrounds, as they tend to disintegrate) - you should be able to find replacement!
Doesn’t the magnet from the unused woofer add weight? I’m really a novice at this restoration of old components. I looked around and these passives are more expensive than the woofer themselves lol
That’s the original passive, I see kits to fix this but only seeing cerwin Vega, and other brands, does that matter? as long as it’s 12 inch?
yes, to the speaker, but not to the diaphragm. it does not lower the resonance frequency.
tuning the passive radiator would require some measurement equipment and some knowledge - not sure if you want to invest money and time for this?
for foam surrounds have a look at:
https://www.repairyourspeakers.com/en/repair-videos/foam-or-rubber-surrounds/c-27
https://www.simplyspeakers.com/Foam-Speaker-Surrounds_c_390-3.html
alternatively you could try to find the same speakers as yours on the used market ... might be cheaper!
depends on your expectations. non-original surrounds may have some influence on the system tuning (bass response), but i suppose it will not be that bad.
So you mentioned weight in a way I am not familiar with, but as I said I am a novice who basically wants a vintage system that works, sounds good with minimal investment, in saying that, I am not an audiophile and wondering if I use one of the woofers as a passive would it change the sound all that much?
usually the passive radiator needs a much lower resonance frequency that the driven woofer (that's what passive radiator is all about); you can do that by adding weight to the diaphragm.
with dedicated passive radiators this is usually possible by adding washers to a screw mounted to the diaphragm.
just taking two identical woofers as "active" driver and passive radiator will result in a peaky but not deep bass response.
of course you can just try it - you won't damage anything. just make sure that the "passive radiator" connection are left open and unconnected. you could even try adding weight to the passive radiator by sticking play dough to it (best position is at the connection between dustcap and cone) and tune it until you are happy. once you found the correct weight you can add it permanently by glueing small lead balls or similar to the same position.
also note that if you just take any arbitrary 12" woofer(s) and put it into the enclosure the chances are low that they will behave similar to the original ones.
i would definitely go for replacement surrounds in this case!