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10" driver into oldschool GK combo


Owen
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I am loath to start another thread when I have done nothing at all on my last topic, but outing the project might embarrass me into actually doing it. I have a GK MB150 combo which needs a new speaker. The original speaker surround
[url="http://s8.photobucket.com/user/peredur/media/Mobile%20Uploads/20161222_162316_zpskbzsinom.jpg.html"][/url]
has perished so it is time to fit a replacement.

Of course, the rational thing to do would be to buy a direct replacement but I got to wondering if any of the more recent drivers would work in such a small box. Obviously it is never going to sound like a Berg NV610, but to get the best out of the box would not hurt. So I asked the people who know

[url="http://basschat.co.uk/topic/296142-new-speaker-in-gk-mb-combo-options/"]http://basschat.co.u...-combo-options/[/url]

and the final suggestion was an Eminence BP102. I picked one up on Ebay for £50 and now I need to fit it into the box

[url="http://s8.photobucket.com/user/peredur/media/Mobile%20Uploads/20161222_162350_zpswq0qjnav.jpg.html"][/url]

Obviously the main problem is that the box is built for a 12" and this is now a 10". I was going to fabricate a spacer ring to mount on the cab and then mount the 10" onto that but it will not leave enough room before the speaker hits the grille. This means that I will have to mount the spacer inside the box and then mount the speaker onto that. Given my awseome woodorking skill this wil be easy-peasy. In a parallel universe. However, I think I can manage it and will take pics. One of the problems I have run into is that the speaker mounting holes are of course threaded screw holes so I do not want to force something through them and wipe the thread off so I will need to get long bolts which are thinner than the small holes

[url="http://s8.photobucket.com/user/peredur/media/Mobile%20Uploads/20161220_163836_zpsmgkyblga.jpg.html"][/url]

This will probably involve buying several sizes from ebay and seeing what works. I am using MDF so am guessing bols with washers for the mount and bolts with T nuts for the actual speaker.

How hard can it be? I am documenting it because my mistakes might well help someone else do it better when it is their turn.

Edited by owen
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Can you get some long pan head machine screws with the same thread as the insert, then screw them in until they're tight?

You could then then use washers and nyloc nuts to attach the spacer ring to the studs protruding on the inside?

If you have a screwfix or toolstation nearby they are a good source of nuts/bolts without waiting for eBay deliveries.

Good luck with the project :)

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[quote name='6v6' timestamp='1482479558' post='3200848']
Can you get some long pan head machine screws with the same thread as the insert, then screw them in until they're tight?
[/quote]

It looks like I can! In Screwfix as well. AND I managed to do it while I was out on licence doing some Christmas shopping.

[quote name='stevie' timestamp='1482495504' post='3201024']
Yes, good luck with this, Owen. You might also consider getting some speaker damping material while you're browing eBay.

Unless they are some awful American size, the screws look like M3 to me.
[/quote]

Does it have to be specific stuff or will any old soft foam do? They are M4. Sadly Screwfix did not have black ones but for the £2.35 or whatever it was worth buying them just to get the size. I will pick up some black ones because they will look proper. I am all about co-ordination!

[quote name='SubsonicSimpleton' timestamp='1482503339' post='3201125']
Why not mount the spacer on the outside of the cab, but mount the speaker to the inside of the spacer?
[/quote]

I had not thought of that, but if do I will have to make the spacer beautiful and tidy. If it is on the inside I can make it rough and no one need know :)

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  • 2 weeks later...

You'd think Screwfix would have a decent selection of screws, given their name, but they are useless for black screws - and stainless steel screws for that matter. The eBay suppliers are pretty good, I've found. Black socket screws alway look the business IMO, although you can always apply some black paint to a chrome screw.

What kind of foam have you got, Owen? Generally speaking, if you blow into it and can feel your breath, slightly delayed, coming out of the other side, it should work. Otherwise, try pillow or sleeping bag filling. My current damping material of choice is felt - also available on eBay and not too expensive.

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Screwfix were great on size but as you say, useless on colour. I took what they had so that I could get on and finish the job over the holidays. As usual life got in the way and I am no further forward.

My foam is basically aluminium brief case kind of foam. That will be a no then. I will find some proper stuff. Thanks - as usual.

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  • 2 months later...

So, many months later I actually managed to get cracking with a jigsaw. There are good reasons why I am not left alone with power tools

[url="http://s8.photobucket.com/user/peredur/media/Mobile%20Uploads/20170304_132543_zpsvgyley4m.jpg.html"][/url]

It went in eventually. I got the right sized screws for the thread in the GK baffle, but of course they were holding onto the baffle and not the nut on the other side. To make it worse I got self locking nuts so they were a but trickier to get on. Eventually I drilled the thread off the GK baffle as I could not get the nut tight enough on the other side.

[url="http://s8.photobucket.com/user/peredur/media/Mobile%20Uploads/20170304_210052_zpstxk9iold.jpg.html"][/url]

I had decided to use Tee Nuts to hold the speaker in place but then realised that drilling the home made baffle out for these left a hefty gap in the wood

[url="http://s8.photobucket.com/user/peredur/media/Mobile%20Uploads/20170304_211945_zpsn7ikjdt6.jpg.html"][/url]

I then managed to bolt the speaker in with the spade connectors to far away from the cables to connect and then the crowning glory was when I put the drill/screwdriver through the cone

[url="http://s8.photobucket.com/user/peredur/media/Mobile%20Uploads/20170304_211033_zpsyjioj9tm.jpg.html"][/url]

It was not a great moment.

It is all bolted together at the moment but I have not had a chance to plug it in due to being late finishing last night and my usual Sunday morning resicdency gig. My gut feeling is that I will need to make a new spacer ring come what may. This is if the speaker will actually work without distorting. Can I repair this kind of damage to the cone?

As I mentioned, there is a good reason I am not left alone with power tools :(

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<sigh> Ho hum. It is fine down to open D and then it struggles bigly. Air coming out of the perforated surround and through the speaker mounting holes. The only saving grace here is that I have enough MDF to make 3 more rings.

Is gaffa going to repair the perforated surround?

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Bad luck about the speaker, I guess it's worth trying to repair but given where the damage is I'd probably chalk it up to experience and find somewhere to re-cone it.

The spacer looks saveable to me? Even if the holes are a bit oversized the tee nuts should end up squashed tight against the wood, you can screw them in with a screw and washer (to avoid damaging the speaker) then do them up tight (I'd use a drill/driver as it may be hard to do by hand).

You could even put some sealant around each tee nut if you're still worried air will leak, and add some gasket tape between the speaker and the spacer to improve the seal?

Good luck! :)

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I'm finding it a bit difficult to follow what you have done, but I can help with the hole in the driver surround. No need for a recone - that's an easy repair.

You'll need to get some of this glue: http://www.homebase.co.uk/en/homebaseuk/unibond-repair-extreme-power-glue---transparent---20g-692332

You could probably get away with just pushing the surround back into place and gluing it, but if you can get hold of some old black tights from your wife or girlfriend (or if you wear tights yourself - don't want to be sexist, do we) :) , cut two small rectangular pieces and glue one to the front and one to the back of the hole. Push into position so that it sticks closely to the contours of the surround. I've used this technique to repair much worse damage than a small hole.

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[quote name='stevie' timestamp='1488792800' post='3251703'] I'm finding it a bit difficult to follow what you have done [/quote]

Essentially I was operating power tools without due care and attention. Thanks for the tip, I have ordered some.

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  • 2 weeks later...
  • 3 months later...

If I ever ask anyone about advice where tools are to be used, can you remind me that I am clueless and should leave well alone? I finally screwed it all together this morning but did not fire it up as I am waiting for the silicone I used to plug the one screw hole which did not seat the T nut properly so it ate out the MDF in the spacer ring to dry.

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