Celestion Loudspeaker Repairs
Celestion Ditton 66 Loudspeakers
These didn't sound right as one was missing high frequencies. Turned out one tweeter was 4ohm the other 8ohm! Someone had been playing with them. Decided due to the age of them, (45yrs) to look at the xovers, glad I did, the capacitors were shot with a fungal growth coming out of one of them. Considering the price of replacement HF2000's, I replaced the tweeters with a pair of Seas H086 and modified the xovers as needed, sounded wonderful after a bit of TLC.
Celestion 3 Loudspeakers
One speaker sounded okay, the other produced a weak sound. Removing the bass drivers and checking the resistance; one was as expected at approx 6 ohms, the other was approx 28 ohms. The voice coil was faulty on the 28 ohm driver and needed replacing.
I had a play around with these speakers and found that the inductor in series with the bass driver had a resistance to DC of 0.5 ohms, so much for the amplifier designers trying to get the lowest output resistance. Anyway, I bypassed the inductor as a trial and it improved the sound quite noticeably, guess this could apply to most speakers out there. Of course you loose the roll off of the high frequency's and rely on the natural roll off of the driver, but sounds fine to my old ears.
Celestion Ditton 33 Loudspeakers
These sounded bad, no mid or treble from one speaker and no treble from the other, found two capacitors in the x-over needed replacing an 8 µF which had extruded itself and a 30 µF which was about 10 µF, replaced these and both tweeters as one was open circuit. This improved the sound dramatically.