DIY Recone thoughts...

De_Batz

Afternoon all,

Have a chassis for a Goodmans Audiom 61 that developed a loose voice coil, and have been contemplating using it to have a go at my first DIY recone. 

Just looking for opinions on a couple of things:
The first is that the VC on the original is about 5/8" deep below the spider, with no former visible between said spider and the VC itself. All of the replacement cone kits I can find with a similar 1 3/4" VC seem to have a longer VC with a bit of former on display between the spider and the coil. I've measured the depth of the gap at 1 3/8", so there's no danger of bottoming the VC out against the innards. Do you think I'll be okay with a deeper VC in terms of the coil sitting in the magnetic field? 

The recone kits available from Lean (etc) seem to vary in price from about £45 to above £80, depending on the speaker. Now, call me cynical if you like, but are the cones for (say) a Gold that much different to the ones used in less expensive kits (the V30 is about £60, and the G12K and H100 kits are less than £50!)?

I get that this is a bit of a dark art and that the chances of a perfect result are limited, but looking to have a go partly for the fun of it! I know that the guy at recones.com gets a lot of recommendations so perhaps if it is a total wipeout that's what to try next...

robgilmo

If there is a former on the VC will it still fit in the magnet? More windings on the coil will change the characteristics of the speaker, not much of an issue unless its one of a matched pair. Will it however change the impedance in any significant measure?

DartmoorHedgehog

I did a DIY recone on a V30 with a melted voice coil I had a few years ago.  It was sold to me as working but had loads of coil rub and was obviously not OK - seller didn't argue and gave me most of the purchase price back, so thought I'd give it a go.  I just did it really carefully, checking there was no rub before I let the glue dry, and it turned out fine - I used it for a few years then eventually sold it for near enough what it had cost me (and as far as I know the person I sold it to is still using it).

I'd say as long as you know the frame is straight and you're generally OK with fiddling with things then do it.  I don't know why some cones cost so much more than others though.

De_Batz

robgilmo said:

If there is a former on the VC will it still fit in the magnet? More windings on the coil will change the characteristics of the speaker, not much of an issue unless its one of a matched pair. Will it however change the impedance in any significant measure?

All of the issue here is in the direction of the movement of the speaker / VC / former; The circular gap in the magnet looks the same or close enough as any other speaker that I've seen taken apart, but I will be messing about with shims to try to centre the thing when I do it. 

The old coil is a 16ohm, with 5/8" of windings on the former, but all of them right next to the spider. The more I look at it, the more I'm convinced that it's a manufacturing error because there must have been 1/4" or so of VC windings outside the magnet gap at rest. I'm sure it should have a bit of distance between the former (should have said) spider and the VC itself. 

robgilmo

De_Batz said:

robgilmo said:

If there is a former on the VC will it still fit in the magnet? More windings on the coil will change the characteristics of the speaker, not much of an issue unless its one of a matched pair. Will it however change the impedance in any significant measure?

All of the issue here is in the direction of the movement of the speaker / VC / former; The circular gap in the magnet looks the same or close enough as any other speaker that I've seen taken apart, but I will be messing about with shims to try to centre the thing when I do it. 

The old coil is a 16ohm, with 5/8" of windings on the former, but all of them right next to the spider. The more I look at it, the more I'm convinced that it's a manufacturing error because there must have been 1/4" or so of VC windings outside the magnet gap at rest. I'm sure it should have a bit of distance between the former and the VC itself. 

Could be, its not hard to repair a voice coil, I did one a few years back, the coil had no former, it was edge of seat stuff but a vintage and very rare super tweeter so , well , nothing to lose I guess, it was already broken and no body that I knew could fix it.
I would try and repair rather or before replace, you have nothing to lose.

De_Batz

robgilmo said:

De_Batz said:

robgilmo said:

If there is a former on the VC will it still fit in the magnet? More windings on the coil will change the characteristics of the speaker, not much of an issue unless its one of a matched pair. Will it however change the impedance in any significant measure?

All of the issue here is in the direction of the movement of the speaker / VC / former; The circular gap in the magnet looks the same or close enough as any other speaker that I've seen taken apart, but I will be messing about with shims to try to centre the thing when I do it. 

The old coil is a 16ohm, with 5/8" of windings on the former, but all of them right next to the spider. The more I look at it, the more I'm convinced that it's a manufacturing error because there must have been 1/4" or so of VC windings outside the magnet gap at rest. I'm sure it should have a bit of distance between the former and the VC itself. 

Could be, its not hard to repair a voice coil, I did one a few years back, the coil had no former, it was edge of seat stuff but a vintage and very rare super tweeter so , well , nothing to lose I guess, it was already broken and no body that I knew could fix it.
I would try and repair rather or before replace, you have nothing to lose.

Wise, but not viable here. The cone itself got torn as I was trying to figure out the problem, and I ended up cutting it away... So it's a whole new assembly required. I supposed I could try to araldite the wires into place on the existing VC but I'd still need a whole new cone...

De_Batz

Interesting experience with this: kit ordered (I bought the V30 one as it was a little bit cheaper than a G12H and has the kapton rather than paper voice coil) and arrived from Lean pretty soon after. 

The kit came with the relevant shims, which was a bit of a relief, because I wasn't sure how I was going to do that. The only real issue was that the magnet housing on the back of the speaker lacks the ridge that couples it to the spider. The old spider was a bit deeper - 1/4" - than the new one (about 1/8") so I had to improvise with a bit of 3mm rubber strip to make it all stick together. 
I did also give the cone edge a bit of nail varnish remover to loosen it off a bit, as the original cone didn't seem to have any of the dope gunge that the V30 cone has in abundance. 

Tried it yesterday at the studio, and it was great. Colour me surprised, but relieved. 

I'd be happy to have another go at the same job, and I'd be able to go at it with a sense that I knew how to do a good job of it...