Coral CX-5 crossover - attenuation control doesnt work

[Synchro-bias]

I love the sound of my Coral speakers. They are very very good speakers, have to be careful due to their low power output
photo of them are from the net.
https://translate.google.com.au/translate?sl=auto&tl=en&js=y&prev=_t&hl=en&ie=UTF-8&u=http://audio-heritage.jp/CORAL/speaker/cx-5.html&edit-text=


I rewired the crossover and refreshed the caps, so i dont see what couldve stopped the mid and tweeter control from working? couldve dust got into the attenuator, as i tried contact spray, but maybe it has to be taken apart to be cleaned ?

 

[onplane]

Neither control works? If that's the case, it sounds like the wiring got messed up. Double check that all wires from the controls are terminated properly.

Jerry

 

[toxcrusadr]

If you have a meter, put one lead on the control's wiper and the other on one of the other terminals, set to ohms and rotate the control. You should see resistance increasing in one direction and decreasing in the other. If you don't have a meter, try putting a jumper wire across the control pots and see if the drivers start working. If so there is a problem in the controls. There are some controls that can be damaged by cleaning solvent, so I've read anyway.

If you replaced all the wiring, it's possible there's a wiring error. Do you have a schematic? If not you can make one (it usually takes me a few tries to make it neat but it's do-able). It's a good excercise in understanding how crossovers work anyway. Trace the signal path from +input back to -input.

 

[Synchro-bias]

Thanks ToxCursadr
I have a DDM, so that would be easy to check, as you sugguested. Control leg - 3 pins (wipers) + , +, -. The speakers sound excellent, but with certain amps a bit bright - could be the wiring i used or without controls is set to maximum.
I hope that cleaning the controls didnt do any harm, they were scratchy with i bought them, so i cleaned them with contact spray

I have a rough schematic

 

[toxcrusadr]

It looks like you knew what you were doing so if you're confident the hookup an soldering are OK, it has to be something else.

I think I misunderstood your original post, thought the drivers were not playing. It sounds like the drivers play but the controls don't change the levels? Then definitely check that the pots are actually attenuating.

Make sure there is no solder residue bridging different traces on the board and shorting things out.

 

[Synchro-bias]

It looks like you knew what you were doing so if you're confident the hookup an soldering are OK, it has to be something else.

I think I misunderstood your original post, thought the drivers were not playing. It sounds like the drivers play but the controls don't change the levels? Then definitely check that the pots are actually attenuating.

Make sure there is no solder residue bridging different traces on the board and shorting things out.

Hi Toxcrusadr,

Yes the speakers are working perfectly, sweat and clear, the Corals must be close to the Yamaha NS1000M in sound, but never heard them though. Just certain amps of mine they are too bright and but i can not adjust the controls. Yes i cant notice any change moving the controls. To test the pots with the DMM, I place one lead on the pot terminal, and other on the board? any particular part of the board?, and yes maybe some solder is touching, though in the pic it looks messy, but maybe worth a check over again. Orange wire is midrange and double thin wire is tweeter and thicker red is the woofer. Its Alpha wire SPC, and the thin is kynar wire from Ok Industries.

 

[imthuong]

Hi Toxcrusadr,

Yes the speakers are working perfectly, sweat and clear, the Corals must be close to the Yamaha NS1000M in sound, but never heard them though. Just certain amps of mine they are too bright and but i can not adjust the controls. Yes i cant notice any change moving the controls. To test the pots with the DMM, I place one lead on the pot terminal, and other on the board? any particular part of the board?, and yes maybe some solder is touching, though in the pic it looks messy, but maybe worth a check over again. Orange wire is midrange and double thin wire is tweeter and thicker red is the woofer. Its Alpha wire SPC, and the thin is kynar wire from Ok Industries.

I’ve just got a pair cx5. Everthing seems fine except the lag of mid, the sound is too dark on my denon 940 and seems only bass on Dewald 1200m. Compare to my Boston a40 its higher at price (200$ vs 150$ used) but the sound is far behind vs Boston.

I miss the middle range so much when i plug in the cx5

After teardown and looked into the crossover i found there is a 0,5 ohm resistor connect continous before the mid cap. I removed it by sold its two head by a wire, and the mid is now much better, the frequency cut the the same but the mid drive has morr energy now.

Here is the sketch of schematic if anyone need it.

 

[toxcrusadr]

Hi Toxcrusadr,

Yes the speakers are working perfectly, sweat and clear, the Corals must be close to the Yamaha NS1000M in sound, but never heard them though. Just certain amps of mine they are too bright and but i can not adjust the controls. Yes i cant notice any change moving the controls. To test the pots with the DMM, I place one lead on the pot terminal, and other on the board? any particular part of the board?, and yes maybe some solder is touching, though in the pic it looks messy, but maybe worth a check over again. Orange wire is midrange and double thin wire is tweeter and thicker red is the woofer. Its Alpha wire SPC, and the thin is kynar wire from Ok Industries.

Looks like I missed your post last month! Sorry about that.

Each pot should have 3 terminals. The center one is the wiper. Put one lead of your DMM on that. The other lead can go on either one of the end terminals - pick one and the resistance will go down as you turn the knob one way, pick the other, it should go up by turning it the same way.

If the control is OK but moving it does not change the output volume, it's possible you connected a lead to one end of the pot that should have been connected to the center wiper. So you'd get a constant resistance (the resistance of the entire pot) with no adjustability. Or something like that. Check that the wiper terminal goes directly to the driver and that the two ends go to the input side of the circuit and to the 40 ohm resistor respectively.

 

[karlson58]

Hello gentlemen and greetings from Germany,
with interest I read these posts to Coral CX5!
I still have two patients who demand my attention.
Unfortunately the tweeters and the crossovers are missing ..!
That's why I would need your help, please. Can you at least give me the value of the bass coil (can not be recognized in the appendix for me?!?!), Better of course would be a complete circuit.
May I hope for your friendly support?
Thank you and best regards
Karl-Heinrich vom Dahl

 

[toxcrusadr]

Hopefully imthuong knows, his schematic shows the values for the other inductors. Unfortunately it appears his post in May 2018 was his only post at AK.