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rubis

B15N style cab build FINISHED!

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The back panel is also now covered, once again I used masking tape to help to get the square pattern lined up.IMG_3954.thumb.JPG.10d9a712fcd4838e2738fe5f516c51ef.JPG

I'm not quite sure what kind of foam to use around the inside of the cab, where the back panel is secured into place, so I am going to try out some the heaviest duty foam strip for sealing doorframes and suchlike, which I found in Wickes. I will put it around the perimeter on the inside of the back panel and also on the inside of the cab where the bolts screw in.

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I'm hoping that with two thicknesses of this foam, which is quite thick, pressed together with machine screws all around the edge, it should be airtight.

Please let me know if you can recommend anything better.

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I have now got the speaker wired up, thanks to those who offered advice on how to do that, it's not one of my confident areas, much appreciated. 

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I thought I would do it while I was waiting for the grille cloth which I had ordered, to arrive from USA, however while I was out watching the man cub playing football, this morning, this arrived, left in the porch.  

Very pleased with this, looks great and no import duty to pay! 

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Best get on with it! 

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Impressively neat work with the tolexing there! I've done a couple of guitar combos, and there's certainly a knack to doing it well. I suspect that Ampeg never put in that level of attention to detail over the check pattern.

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I am in the process of making as sure as I can that there will be no leaks or rattles on this cab, an I have another advice question for you all please. 

What would you recommend to use for lining the inside of the cabinet?

I have four squares of egg-box style foam lying around that I was going to use on a guitar cab, so I tried that in there, but I think it's a bit too thick. It will lie very close to the slotted holes on the front baffle, and I worry that they would not be able to function as they are intended to. 

I then thought I could cut up to completely cover the back panel, and use something thinner an less obtrusive on the sides? 

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Is there any kind of best practice involved with lining cabs?

What's the best stuff to use?

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3 hours ago, rubis said:

I am in the process of making as sure as I can that there will be no leaks or rattles on this cab, an I have another advice question for you all please. 

What would you recommend to use for lining the inside of the cabinet?

I have four squares of egg-box style foam lying around that I was going to use on a guitar cab, so I tried that in there, but I think it's a bit too thick. It will lie very close to the slotted holes on the front baffle, and I worry that they would not be able to function as they are intended to. 

I then thought I could cut up to completely cover the back panel, and use something thinner an less obtrusive on the sides? 

IMG_4035.thumb.JPG.99fd9abd230f407aa9f1448f6ed0202b.JPG

Is there any kind of best practice involved with lining cabs?

What's the best stuff to use?

This is very good

envirolay-54oz-felt-from-2.35-per-square

https://www.carpet-underlay-shop.co.uk/products/42oz-wool-felt-carpet-underlay?utm_medium=cpc&utm_source=googlepla&gclid=Cj0KCQiA7aPyBRChARIsAJfWCgLynaEOwvFjRporrkF8Z863-a6Q6kvRIk758FvbSNwQlRHRnHFGUh4aAvX8EALw_wcB

Edited by Christine

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Best practice for internal speaker damping is not to overdo it, especially with a ported system (which I assume this is). You're right to keep the damping well away from the slot ports.

So try what you have and then carry out a before-and-after listening test, paying particular attention to the lower bass. If you find that the damping is removing too much of the very bottom end (quite likely if you cover all the walls with foam), take some out, or use a thinner material like BAF wadding (pillow or duvet stuffing).

My go-to material is now felt - so I imagine that felt carpet underlay would work well. I've wanted to try it myself for a while but I've never found anyone willing to sell me a couple of square metres.

 

Edited by stevie
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I'm sure I read - but I can't find it now - that you can tune the damping in a cab just by snapping your fingers in it. If it sounds reverberant, it needs more damping, and if it sounds dead, it needs less damping - the optimum is somewhere between those two.

Can any speaker builders confirm that the principle is right?

David

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In principle, yes, that's right. I used to stick my head in the box and say 'testing, testing'. Even though I use more scientific methods nowadays, I still do it.

If it sounds hollow, add more damping until it sounds dead.

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Thank you kindly folks, I got some of the wool felt underlay stuff on the way home from work today. 

It looks just like the stuff Christine recommended above (thanks again)

I think I will fart (probably the wrong word) about with it, holding it in place with double sided tape, until it sounds right, as per the advice above, and then use up the spray glue I have left from telexing for a more permanent job.

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Terrible visions now of you repeatedly farting into the cab to check if it echoes,  and after the fourteenth time asphyxiating when you put your head in it it to adjust the felt thickness 

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Maybe using a small duck to test the cab would help.  There is however a popular notion that a duck's quack does not have an echo.

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I've been having a bit of fun with a logo for the front of this cab, but first let me explain how the name Rubis came about. 

When I began my first guitar build a few years ago now, our two kids (now teenagers) were just toddlers really, and while they were 'helping' one day I said that we'd have to think of a name for our guitar company, and without hesitation the reply was Rubis…….their names are Ruby and Lewis, and so it seemed a perfectly sensible choice. 

So I was looking at the Ampeg script on the front of the B15 cabs and thought I could play around with it. 

I got one of these on Ebay, they're made of plastic and perfect for messing with

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I then began chopping and filing to try to make it say Rubis. The only problem I had was making a convincing letter 's'.

I tried cutting a little sliver of the chrome effect finish to fill in a gap that shouldn't be there, but it didn't look right. 

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So in the end, we decided to leave the repair out, it looks neater without it, not perfect, but better. 

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Nice touch!! that’s exactly the same reason why I put ‘Brash’ on the headstocks of my builds (my kids Bradley and Ashden)..........👍

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On 17/02/2020 at 19:10, rubis said:

Thank you kindly folks, I got some of the wool felt underlay stuff on the way home from work today. 

It looks just like the stuff Christine recommended above (thanks again)

I think I will fart (probably the wrong word) about with it, holding it in place with double sided tape, until it sounds right, as per the advice above, and then use up the spray glue I have left from telexing for a more permanent job.

How did it turn out?

We used to make prototype speaker cabinets for the HiFi World magazine years ago, the designer used to specify that underlay

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@rubis - would you like to sell me some of the felt underlay you have left? I can't source it locally and the cost of a roll from the mail-order suppliers is a bit steep just for an experiment.

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On 24/02/2020 at 22:41, Jimothey said:

Nice touch!! that’s exactly the same reason why I put ‘Brash’ on the headstocks of my builds (my kids Bradley and Ashden)..........👍

Yer me too, I put Fender on my Bitsabass builds after my kids FENton and DERry.😂

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Finally finished!

There were just a few finishing off jobs to do, but for some reason it took a while to get them done. 

I took a bit of trouble to try to make it as airtight as possible, I've not made a cab, or even looked inside one, but from what I've read about this design, ownership is as much about chasing squeaks and rattles, as about enjoying the sound it makes! 

So, I got some adhesive spray, some sheets of black felt and foam, both about 1mm thick, and pinched a load of tricks from others, that will hopefully each make a little bit of difference.

I glued rubber patches on the inside where the bolts for the handles come through.

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Then made one with a smaller diameter hole than the speaker socket, so that it stretched over and made an airtight seal.

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I glued a bit onto the spacer blocks on the back of the grille panel, as I have read these are a source of rattles. 

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Then I followed the advice of Mark at Vintage Blue in the USA, I covered the other side with the black felt, it seems back in the day, they were covered with some sort of foam or similar, which was there to stop the grille cloth from rattling against the outer baffle. These would disintegrate over time and the cloth would flap against the front of the cab.

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Then I glued the wool felt to the inside of the cab, oh what sticky hairy fun that was!

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Then once again, following Mark's example, stapled on the grille cloth

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and heated it up in the oven to tighten it up onto the baffle, and bugger me it worked!

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This was quite satisfying!

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On went the back panel, and that was it!

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Posted (edited)
On 25/02/2020 at 09:33, stevie said:

@rubis - would you like to sell me some of the felt underlay you have left? I can't source it locally and the cost of a roll from the mail-order suppliers is a bit steep just for an experiment.

Stevie I have a bit left over from this, it's about 150x140cm, you're welcome to it if you want it?

PM me your address and I will post it to you. 

Edited by rubis

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