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SpeakerLab 7WA Crossover

DaWoofer

DaWoofer

Super Member
My midrange and tweeters work fine but the speakers sound like there is a wool blanket over them. I'm sure they were not intended to be so dark sounding from the factory. This leads me to believe it is time for capacitor change out. Of course we all know the speakers are glued in with silicone sealant so I don't want to pull them all. Does anyone know if the crossover components are behind the 12" or 10" woofer or higher up? Also, does anyone know what the value the caps are or have the schematic for these? Thanks gentlemen for whatever info you might have.
 
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Pull all of them and replace them with t-nuts into plywood shims and use gasket tape on the rear of the woofers. You'll thank me later.

By the way, the crossover is typically mounted on the binding posts.
 
O.K cool, I just found a couple different schematics along with the one I need. Can the crossover come out through the back? Wishful thinking I'm sure.
 
DaWoofer said:
O.K cool, I just found a couple different schematics along with the one I need. Can the crossover come out through the back? Wishful thinking I'm sure.
Click to expand...

If the cabinets are build by the factory I'd bet my money that the only access point is through the drivers on the baffle :yes:
 
Don't be shy about trying to remove the caulked-in larger drivers. It is not that difficult. It's the smaller drivers that have the flanges tucked into recesses that can be difficult.
 
They are probably 10 watt. I'd replace them while your at it, you can replace with 10 watt resistors from madisound (mundorf, green resistors) or mills from partsexpress.com You could also put two 30 ohm 10 watt resistors in parallel to achieve 15 ohms at 20 watts.
 
They are wired in parallel the way the schematic shows, two 15 ohms in parallel in the tweeter and two in parallel for the mid. Did you replace yours? Seems like the tweet and mid would only be seeing about 7.5 ohms, is that correct or am I confused as normal.
 
Well crap, I ordered parts of the schematic(s) that I found online for the 7WA's and come to find out their are more parts inside the cabinet then I expected. There are 2 more 2uf's that were not on the schematic and a 36 uf never mind many more resistors that were not shown. There is one yellow looking object I'm guessing is a cap that is rather oval in shape and has the markings of 2+-10% 250 and in smaller numbers next to that is -909 and is made by Shizucki. There are no uf marking on it. Does anyone no what it is? Here are a few shots of the crossover. The inductors were just laying in there loose and on of them had the wire crossed were it would be shorting together.Time to reorder as soon as I find out what that yellow cap looking unit is. Any help guys.
 

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DaWoofer said:
Well crap, I ordered parts of the schematic(s) that I found online for the 7WA's and come to find out their are more parts inside the cabinet then I expected. There are 2 more 2uf's that were not on the schematic and a 36 uf never mind many more resistors that were not shown. There is one yellow looking object I'm guessing is a cap that is rather oval in shape and has the markings of 2+-10% 250 and in smaller numbers next to that is -909 and is made by Shizucki. There are no uf marking on it. Does anyone no what it is? Here are a few shots of the crossover. The inductors were just laying in there loose and on of them had the wire crossed were it would be shorting together.Time to reorder as soon as I find out what that yellow cap looking unit is. Any help guys.
Click to expand...

That's a 2uF 250v film cap. No need to replace it unless you want to. I'm very interested to hear how your upgrade goes. I have that very same pair of speakers with the very same problem!

Markus
 
How did you figure that it is a 2uf. It seems like they would of used the same one as they use 3 in their besides that one that we are talking about. Why change to something different. There is a 2uf parallel to the 12 uf and two 2 uf''s in parallel besides the Shizucki in use.
 
Just curious DaWoofer- what mid horn driver you have? You m ight also consider putting in low dcr loss iron core inductors on the woofer end. I would also be temted to upgrade the wire as well.......rebrace the cabs, etc while you are in there. What Sir Byrd did with his was a good example of an u[pgrade I thought!
DC
 
My cabinets have cross bracing already and seem to have enough inductors as it is although not iron core. Are you saying these are not low DCR? would I replace with same value just use iron core? I did't pull the mid driver so I really don't know which one it is. I got a couple days to wait on more parts so I might just pull them to find out. So what advantages ca I expect with iron core inductors?
 
DaWoofer said:
How did you figure that it is a 2uf. It seems like they would of used the same one as they use 3 in their besides that one that we are talking about. Why change to something different. There is a 2uf parallel to the 12 uf and two 2 uf''s in parallel besides the Shizucki in use.
Click to expand...

Not sure why they would have used something different, but it sure looks for all the world like a flat film cap. I've got a bag of those. Are the other 2uF caps 250 volt? Maybe this one needs higher rating due to where it is in the circuit. The picture is little blurry though, so maybe I'm mistaken.

Markus
 
No, the others are all 100v, I didn't think about that. I'm replacing all the others might as well replace that but I'm still stumped on the size because of no markings that say 2uf. I'll retrace the wires and see if that is the one in the schematic and not the others.
 
You can gain a bit more responce with a lower dcr inductor on the low end. Using the large air core inductors cost you some db over the typically lower dcr of iron core types. The mid and tweeter I would not bother with so much on the inductor C/O, but the low end might help ya some.

Those old grey electrolytic caps should be replaced- bet the "esr" is out of sight on them.....

Good luck- the "7's" can be good sounding speakers when all is right, you should be well on your way now.
DC
 
You are likely never going to have 250 volts going into your speakers, let alone 100. The film cap is likely used in a more critical part of the circuit where you get the most bang for your buck, such as in series with the midrange or tweeter driver, as apposed to a shunt parallel to the woofer (where it doesn't really matter)
 
By the way, it will be ok to put a 40 uf in place of the 36 uf that in there won't it? By the way, I checked ESR on those caps and they all were very, very low. Also that film in part of the tweeter network so I'm going to replace it with an audio grade Dayton.
 
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