Fitting new woofers

[tuathal]

Greetings all,

A friend of mine asked my advice on replacement woofers for an ancient pair of Goodmans RB20 speakers. I told him to buy the cheapest 8" woofers he could find in the shop as the speakers are a pile of crap. he came back from the shop with a pair of Eminence 8" woofers (they didnt have anything else).

anyway i installed them and nothing happenend, ie no sound came out of the woofer . the old woofers were 8ohms also.
on the back of the woofers one of the connectors has red paint on it so i presumed this to be the pos terminal? i realise there probably not a match made in heaven but any speaker connected with the right polarity should work to some degree shouldnt it? I also tried the woofers in a pair of Pioneer speakers with the same results. Is this something to do with the crossovers in the speakers?

any ideas would be appreciated..cheers

[bhg41088]

have you tried just hooking up the speaker full range to any amplifier?

[wunhuanglo]

You're quite correct - it should work to some degree.

Three possibilities occur to me.

One is that the sensitivity of the replacement speaker is quite low, and so you have to turn it up quite high (feed it a lot of voltage) to get it to play

Two, if you're holding the woofer out in the free-air, while the other speaker driver(s) are sitting in the box and you play the speaker, you might think there's no output. It's amazing how little sound production you get in free air, even from a 15" speaker, due to "short-circuiting" the front and rear wave. Hold it to the box if you're testing to isolate the rear wave.

Three, the speaker's just blown, no-good. Get a dry cell, like a D-cell (a 1.5 V cell) and connect it to the speaker, polarity doesn't matter. One lead from battery to speaker. The second lead on the speaker, and just tap the second lead on the battery intermittently to confirm that the cone moves and the speaker's good.

Replacing an 8 ohm speaker in a system that already has an 8 ohm speaker should definitley do something.

[tuathal]

"have you tried just hooking up the speaker full range to any amplifier?"

-nope , but i will thats a good idea..

the 1.5V battery test is also a good idea..ill test em both out and let you know..

thanks for your replies!

[tuathal]

oh yeah, wunhuanglo, i screwed the woofers into the cabs before testing so thats not the problem

[tiroth]

The simplest explanation would probably be there was nothing wrong with the old speaker drivers, but there was something wrong with the crossover.

[tuathal]

yeah thats what i thought so i tried them out on Pioneer speakers, same results and the crossover is definately good in them..i think theres no telling untill i give'em the battery test..
Cheers

[tiroth]

Ah, I understand now. Yeah, that doesn't make much sense. You wouldn't expect to find a pair of brand new drivers both with open voicecoils.

[tuathal]

hi..back again,

i tried the battery test, the woofers moved and maked a crackling niose when the 1.5v was applied.

When i connected the woofers full range style, ie directly to the output of the amp, the sound was incrediby tinny, no bass whatsoever .

the wires i used to connect the woofers to the amp were really low grade speakers cables but surely they wouldnt make that much of a difference.

any ideas as to what the problem is?

Cheers

[pinkmouse]

If the drivers were not in an enclosure when you tested them, then you will get little bass response. What happens if you test the drivers in the boxes?