Ls400 Woofer Replacement

[malcolmdc]

Hi - Can anyone help, as I need to replace the rear shelf speaker of my Mk 1 LS400. The roll around the cone has disintegrated, and the speaker unit does not seem to have symmetrical 4-bolt fixing, making an aftermarket stock unit difficult to mount? If anyone has such an original item lying around, in England South-east-ish, I would be delighted to hear from you, or advice if someone has replaced one of these with a non-original unit - Cheers.

[steveledzep]

In the HiFi world, rotted surrounds of old loudspeaker cones are often repaired with new foam/rubber.

Have a word with Wilmslow Audio, they may be able to help restore your original unit.

[CustomIce]

Or, source a nice bit of marine ply, make an adaptor sheet (must be at least 15mm thick) can use MDF but it goes soft if it gets damp.

Secure adaptor to original location and screw new sub in place.

You will need to be aware of the impedance of the stock sub so as to match it to the amplifier.

This is often stamped or printed on the sub basket, if not a multi meter set to resistance will give you an idea.

Readings around 2.8-3.6 Ohm mean a 4 ohm sub, lower than that is either a 2 ohm or 1 ohm or short circuit!

Readings int eh 6 ohm region mean an 8 ohm sub.

Reason - resistance and impedance are quite different beasts, but are related.

You will also need to make a note of the polarity of the sub - which wire is +ve, or you'll cancel bass out with phase inversion.

HTH

[cruisermark]

Or, source a nice bit of marine ply, make an adaptor sheet (must be at least 15mm thick) can use MDF but it goes soft if it gets damp.

Secure adaptor to original location and screw new sub in place.

You will need to be aware of the impedance of the stock sub so as to match it to the amplifier.

This is often stamped or printed on the sub basket, if not a multi meter set to resistance will give you an idea.

Readings around 2.8-3.6 Ohm mean a 4 ohm sub, lower than that is either a 2 ohm or 1 ohm or short circuit!

Readings int eh 6 ohm region mean an 8 ohm sub.

Reason - resistance and impedance are quite different beasts, but are related.

You will also need to make a note of the polarity of the sub - which wire is +ve, or you'll cancel bass out with phase inversion.

HTH

talk about knowing your stuff!! lol

[CustomIce]

I do electronics and cut my teeth in pro audio repair ;)

I have a bit of an understanding you might say :)

[cleverdick]

Definitely try David Smith of DK Loudspeaker Service. He's based in Romford and is a true expert in reconing / drive unit refurbishment. He very successfully fitted a new surround to the LF unit in the MK1 I had, and in fact I've sent drive units to him several times for repair. Very reasonable cost, too.

The difficulty you will face in replacing the unit with a generic one, aside from the Thiele-Small parameters, is that the mounting lugs are different heights. There is no pattern drop-in replacement.

[CustomIce]

Definitely try David Smith of DK Loudspeaker Service. He's based in Romford and is a true expert in reconing / drive unit refurbishment. He very successfully fitted a new surround to the LF unit in the MK1 I had, and in fact I've sent drive units to him several times for repair. Very reasonable cost, too.

The difficulty you will face in replacing the unit with a generic one, aside from the Thiele-Small parameters, is that the mounting lugs are different heights. There is no pattern drop-in replacement.

the likelyhood is you'd get away with an infintie baffle (free air) sub

But repair is more likely to produce the best outcome.

[malcolmdc]

Thanks for the input so far - thought that the market wouldn't be able to match the original! Rather than indulge in woodwork and electronics, I have traced a tested dismantler's item, which may be the lesser of many evils - hopefully age has been kinder to the replacement than it has been to mine (and indeed to me!). Bloody sight cheaper than a Lexus replacement would be, so worth a punt.

[steve2006]

I think I may have a good OEM one in my "stores" I'll check and come back to you.

[The-Acre]

Even if you get an original as a replacement it may still be worth replacing the rubber, unless it's 100%, it's not too difficult.

[malcolmdc]

Thanks again Guys, an internet search found a helpful company Oop North, who came up with a new-looking replacement they claimed was an upgrade on the original (still Pioneer) and it has done the business (and probably my ears . . . )

[Ruud]

May I ask what company that was?