Any one know how to fix my speakers?

[winchman]

A long time ago I spent a fortune on a set of HIFi speakers .
They still sound fab but one distorts at low volume, it sound ok when loud.
Any ideas whats up?
Could it be the cross over? I have taken the driver out and it looks fine no rips etc.
Any ideas? as they are too good to bin
They are Principal Design PD150

[AbyssDJ]

sounds more likely to be the amplifier to me. is the volume digitally controlled, or an analog knob?

[bezzabsa]

got some nice wharfdales that could be up for grabs ;)

[winchman]

Its the speaker tried different ones and they where ok
Which Warfdales?

[AbyssDJ]

what kind of distortion is it... over all frequencies, or just bass? just treble?

[strapping young lad]

it could be damaged cones though

[winchman]

It tends to be lower notes

[AbyssDJ]

if they've been pushed hard then it could be a damaged cone or voice coil... i doubt its the crossover. check the wiring on it...

[winchman]

Not been pushed hard at all, how do I check the cross over?

[AbyssDJ]

difficult to say really... its usually something that either works perfectly or blows completely.. hence why i dont think thats what it is.

i reckon you've got a damaged voice coil... check the wiring on the speaker itself if you can

[winchman]

So I just disconnect the speaker drive unit and test it for resistance?
Think they are 8 ohms

[Evilgoat]

So I just disconnect the speaker drive unit and test it for resistance?
Think they are 8 ohms

Wont work

The resistance is reactive, you cant just meter it out :) BUT if you see 0 something is wrong.

If its a scratchy type noise then at some time the voicecoil has been overdriven and melted.

Power everything off and isconnect the speaker. GENTLY place your fingers equidistant round the cone halfway between the center and the surround and push using as little force as you can, dont give it a shove. The cone should move smoothly untill it hits its maximum mark, you should not hear anything when you do this. if there is a grating nise/scratching sound or it doesnt move smoothly then the speaker is probobly toast. If thats ok, then inspect the foam surround and the centre cap. Make sure the surround is intact and attached to the cne and chassis all the way round. Make sure the cap is secure and not comming away rom the cone. If the cap is comming away, turn the speaker on its back cone facing up and press the cap down gently so its makes contact again (dont cave it in) then pour a small amount of shellac (or clear nail varnish) around it and let it dry before releasing.

[winchman]

Well it never fails any question we ask some one knows
Thanks I will have a look and let you know

[AbyssDJ]

theres allsorts it could be really... hard to say without looking at it. goats advice is good though, give it a try. it all depends on what kind of distortion it is, whether its signal distortion or physical distortion, etc etc

[dew1911]

Advice up there sounds good.

I've got 4 JVC speakers hooked through my Hi-Fi and then my PC, now I push them HARD and they've yet to even faulter.

[AbyssDJ]

most likely because your hifi isnt powerful enough, dew. the first thing you will get is signal distortion in the form of a square waveform, which has the same effect on a speaker as hitting it with a hammer.

many people in the PA and particularly the mobile disco world believe that if they have an amp thats not quite as powerful as the speakers are rated, they will be fine for life ;) quite the opposite... your amp should actually have a higher rated power than the speakers.

[Evilgoat]

most likely because your hifi isnt powerful enough, dew. the first thing you will get is signal distortion in the form of a square waveform, which has the same effect on a speaker as hitting it with a hammer.

many people in the PA and particularly the mobile disco world believe that if they have an amp thats not quite as powerful as the speakers are rated, they will be fine for life ;) quite the opposite... your amp should actually have a higher rated power than the speakers.

Standard systems I put into clubs were 1.5Kw per channel, 9 channels and 1.1Kw Speakers in all but 2 clubs. this is also 1.5Kw of REAL power not 'Car Stereo' power

Tiny little 2u rackmount Toa Crown amps and mahoosive Cerwin Vega speakers, you should see what happens when speakers fail at that level. JBL Epicentre and Bass Setups in some wasnt far off a 90 in size (and weight)

Its possible to vapourise an amp because it cant deal with the draw from the speakers, especially inf the imnpeadance isnt matched. I wont go into the details but speakers are known as reactive loads as they arent just consumers of electrical current but can produce their own. There areso many pitfalls that people arent aware of if you want a perfect setup, for instance, just having uneaqual speaker cables, especially in a surround system, is a common screw up. Or having the polarity reversed.

[AbyssDJ]

thats the thing though isnt it? so many things to be overlooked, especially in an RMS power situation like PA systems. and the biggest of them all is people that dont bother to/dont know about setting the gain structure!!!! simple way to turn a top of the world funktion-one system into a harsh sounding mess.

most of the stuff we sell to clients now is active, usually from dB Technologies and RCF. some extremely nice systems available from both of them... particularly the dB Fiftyline and RCF 4Pro gear. wouldnt turn down a sale for the new line arrays though :D

[Evilgoat]

thats the thing though isnt it? so many things to be overlooked, especially in an RMS power situation like PA systems. and the biggest of them all is people that dont bother to/dont know about setting the gain structure!!!! simple way to turn a top of the world funktion-one system into a harsh sounding mess.

most of the stuff we sell to clients now is active, usually from dB Technologies and RCF. some extremely nice systems available from both of them... particularly the dB Fiftyline and RCF 4Pro gear. wouldnt turn down a sale for the new line arrays though :D

Hmm, debating on wether I should PM you a load of stuff :) Have some stuff here that would make your toes curl ;)

[Range Rover Blues]

Back tot he orignial question, it could also be a dry joint somewhere.

[AbyssDJ]

go for it goat :)

the only thing with it being a connection is that it would distort more at a higher volume, as it would square off the signal

[Range Rover Blues]

Well I've had the opposite problem, bit of power was needed to get the current through.

Incidentally did you know that a dry joint can form a diode :?:

Simple crystal radios were made by POWs in WW2 using a piece of coiled wire and a lump of coal.

[Evilgoat]

Dry joints can do allsorts of horrible things :) They also heat under load, good way to set light to a speaker.

I suspect int his case the cone/coil is fubar. Did we try moving it manually?