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Hi Guys , so after a very kind member donated his spare caps I have now removed the old black ones and replaced them with the donor ones and my tweeters are still not working ( I know they work when wired direct ). The same member also sent me a bunch of smaller blue alcap ones so I'm thinking I must use this too but I don't know which ones I replace those with on the crossover??
Never, connect a tweeter directly to an amplifier output without a suitable filter, easy way to end up with a blown tweeter.
In most cases if the volume is kept lowish, a suitable single 2 uF capacitor can be used in series with the tweeter to check it.
I suggest measuring the tweeters with a multimeter set on the the Ohms range. Your tweeters might measure around 4 to 6 Ohms.
You replace like-for-like, so whatever value the original caps were (this should be marked on them), replace with the new ones of the same value (which should also be marked on them).
As a general rule, if the XO uses electrolytic caps, do not substitute polyester (MKT) polypropylene (MKP), film & foil or oil-types for them, unless you can measure the system response & are happy redesigning the filter. The ESR of the original electroyltics will almost certainly have been accounted for in the crossover, so any changes there will alter the behaviour away from what they were designed to have. That said, if the original electrolytics have dried out, they will already have drifted somewhat from that. Nevertheless, no point in making multiple changes to the speaker's voicing at the same time.
Understood, thanks
were they working before you bought them?
have you done anything to cable connectors at the back of the speaker?
i ask because when i changed the terminals i didnt check to see if they were properly insulated from the plate they screw against,they weren't and it caused the speaker to stop working,when tested separately the drivers worked,might be worth a check.
Hi Andy,
The Blue capacitors are for the mid range (red caps). You have 1 x 6uF and 3 x 10uF for each speaker, the 10uF caps need to be soldered together to make a total of 30uF. The red capacitors should have the values labeled, if not check out one of Ken's diagrams from the link I posted in your other thread.
Hi , the tweeters were not working on both when I got the speakers home, all other drivers are OK , when I test the speakers directly ( with a dab stereo on very low volume) they work but when I test them with my cheap multimeter there's nothing !! ( other drivers show ok on multimeter)
Also the larger new donated caps show nothing on multimeter when all the other caps do show a reading
Hi Jamie , only the tweeters not working .
Hi
If you send me your tweeters and are happy to cover return P&P, I will run a full frequency test on them at varying voltages which will show up any issues very clearly on the corresponding impedance curve. If you include the caps that you say don't show any reading, I can test those too for you. No charge, happy to help.
As Scott says, only replace like for like when it comes to speakers using electrolytics, although you can sometimes get away with using MKT/P caps in the situation where the original was a low loss capacitor at higher frequencies (but it will still slightly alter the voicing and often, the phase response accuracy providing the originals were designed to be phase aligned properly in the first place!).