Diagnosing a speaker problem?

Fuengi

...well actually, it's a tweeter from a set of Hi-Fi speakers. A Celestion HF1300 from a pair of B&W DM4 speakers. 

How do I detect if it's the driver that is knackered, or if it is not getting any signal feed from the crossover?

Please bear in mind that I can just about use a multimeter and will need absolute clarify on which one of the seven hundred dials to set it to. 

ICBM

Get access to the back of the tweeter - on a hi-fi speaker they’re usually front-loaded - and disconnect one of the wires.

Set the meter to the lowest resistance range - usually 200 ohms - and measure across the terminals. If it’s an 8-ohm unit it should read about 6 ohms.

Fuengi

ICBM said:

Get access to the back of the tweeter - on a hi-fi speaker they’re usually front-loaded - and disconnect one of the wires.

Set the meter to the lowest resistance range - usually 200 ohms - and measure across the terminals. If it’s an 8-ohm unit it should read about 6 ohms.

Thanks for this @ICBM I tested it today and it is the tweeter for sure. Should be able to find a replacement but one day will have a look inside to see if I can repair it. 

ICBM

At the least you'll need to replace the diaphragm if they're available separately, but it may be easier to just replace the whole unit. They seem to be quite common on Ebay - they were apparently used in a lot of different speaker models.

Fuengi

ICBM said:

At the least you'll need to replace the diaphragm if they're available separately, but it may be easier to just replace the whole unit. They seem to be quite common on Ebay - they were apparently used in a lot of different speaker models.

These ones have a metal domed back and are 16 ohms, which seem to be less common.

Fuengi

@ICBM is there anything you can tell me about these crossovers that might be useful? 



The date on the bass drivers is 6 Nov 1979 so they could probably do with a recap I guess? 

Interesting that the front panels are bookmatched. These are hidden behind the speaker grille, yet they still matched them up.



It's less of a veneer, and more of a cap being 5mm thick. 

ICBM

Not a lot to tell about the crossovers other than that they're probably manufacturer-own since there are no identifying marks or anything. The caps are all non-electrolytic so they will be fine.

The HF1300s seem to be usually described as tweeters, but they're clearly midrange drivers here since the actual tweeters are the small domes.

Fuengi

ICBM said:

Not a lot to tell about the crossovers other than that they're probably manufacturer-own since there are no identifying marks or anything. The caps are all non-electrolytic so they will be fine.

The HF1300s seem to be usually described as tweeters, but they're clearly midrange drivers here since the actual tweeters are the small domes.

That's really good to know about the caps, I shall leave well alone. 

My understanding is that the HF1300s are tweeters, and the drivers above those are Coles 4001 Super-Tweeters which come in around 14kHz. 

Fuengi

Reviving this thread in the hope that somebody * glances at @ICBM * can offer any advice on maintaining these DW200/4 original bass drivers. 

Despite the online doom about these early original versions with the white surrounds cracking and splitting, mine appear to be still in very reasonable condition and certainly sound good.

Is there anything I can do to clean / maintain / help to keep them flexible to give them every chance of lasting a bit longer? 

I'm not even sure what the material is. 

ICBM

The only advice I can give is to keep direct sunlight and any sort of solvents - including furniture polish - well away from them. Keep the front grilles on if you have them. I don't think there's anything else you can do - when the plastic degrades chemically it's game over. I haven't seen any like that for decades!

Fuengi

They have that lovely softness to the bass, whilst still being pronounced.

I'll take your advice and cover them up.