DIY Speaker cab and experiment.

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Petebass
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Re: DIY Speaker cab and experiment.

Post by Petebass » 12 Mar 2010, 07:56

thebman wrote:I'm like an annoying apprentice....What type of ply is that Pete?
Have you gone for 12mm or 18mm thickness?
Questions, Questions, Questions.
It's nothing fancy, but I've used it before with good results. It's 12mm hoop pine ply. Picture me at Bunnings pulling out plywood sheets one by one and putting the cracked and crooked ones aside until I find enough good pieces.

As for why I use 12mm when everyone else uses 15mm or 18mm, it's a matter if weight. More that later when I get around to doing the bracing.
Last edited by Petebass on 13 Mar 2010, 07:17, edited 1 time in total.
* 2 Stingray 5's (one heavily modded), Ibanez SR805, Ashbory, + more...
* Carvin B1500, Epifani PS1000, Ashdown Superfly amps.
* Lots of DIY neo/lightweight cabs including one made from composites http://www.ozbassforum.com/viewtopic.php?f=5&t=2546

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Vege-mity-mite
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Re: DIY Speaker cab and experiment.

Post by Vege-mity-mite » 12 Mar 2010, 09:57

Very cool. I can see a spike in the number of router accidents in the next few months...

Keep up the great work Pete!

black_labb
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Re: DIY Speaker cab and experiment.

Post by black_labb » 12 Mar 2010, 10:14

looking good. the makers edge trick is a good one. i use it for alot of things.

when i do speaker cabs i get them made from mdf as i can get it precut to size at a great price from bills board factory in chatswood. you buy a board or a half board, give them the instructions on how it should be cut, come back a day or 2 later and its cut to size and you have spare pieces to use as a makers edge. is cheaper than a board the same size from bunnings. couldnt be easier as they come out perfectly to size with good edges. they dont do ply, its mainly mdf and malamine chipboard pieces which is a downside.

i'm planning on rebuilding the larger of my 1x15's to be the same size as the smaller one and do it out of ply so i will probably be using this method.

raginReggie
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Re: DIY Speaker cab and experiment.

Post by raginReggie » 12 Mar 2010, 18:36

very interested how this one turns out
overall i think the materials used will have a fairly different effect on tone
the composite one i reckon will have alot more mid range haha
im not basing that of anything really just taking a swing haha

cant wait for the next update :yep
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LimeB
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Re: DIY Speaker cab and experiment.

Post by LimeB » 12 Mar 2010, 19:13

So the ply is not marine or any special grade?

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Petebass
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Re: DIY Speaker cab and experiment.

Post by Petebass » 12 Mar 2010, 19:18

I got some more work done today.

first I marked out and cut holes for the speaker, tweeter and port:-
Image

Just a quick check to make sure it all fits... perfect :) At this point I weighed the timber again and as I predicted yesterday, it bought the weight down to 7.1kg of wood. Not bad!
Image

Now I put it all together. I usually just glue and clamp it initially using Aquadhere PVA glue (exterior grade coz it’s a stronger and resistant to accidental spills), F-clamps and simple Butt joints. By the time I was finished here, all 6 panels were in place and there were at least a million F-clamps holding it all together. I let it dry overnight. No screws yet, they come later.
Image

While that's drying I'll wire up the crossover for the tweet. It look a bit agricultural but it works nicely. the hot melt is just to stop the components rattling around or breaking loose.
Image

then I did some work on the jackplate. I had this one lying around from a previous build and it had holes pre-drilled for 2 speakons and 2 jacks. so that's what I went with:-
Image

Then I wired it all up:-
Image

I also did some work on a notch filter to tame the 2.5K hump I mentioned earlier.... actually I made 2 and I'll trial them when the time comes and use the better one.

By tomorrow the glue should be dry enough to get on with the rest of the build.
* 2 Stingray 5's (one heavily modded), Ibanez SR805, Ashbory, + more...
* Carvin B1500, Epifani PS1000, Ashdown Superfly amps.
* Lots of DIY neo/lightweight cabs including one made from composites http://www.ozbassforum.com/viewtopic.php?f=5&t=2546

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thebman
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Re: DIY Speaker cab and experiment.

Post by thebman » 12 Mar 2010, 21:17

Very nice work Petebass, will their be much internal bracing needed to stiffen it up?
lovin that front port, I remember reading a TB thread about the option of reversing the front panel layout of a 2nd cab so the tweeters are next to each other when cabs are stacked together. Hope that makes sense.
Is their any benifit in doing that or is it simply aesthetics.
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Petebass
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Re: DIY Speaker cab and experiment.

Post by Petebass » 12 Mar 2010, 21:30

thebman wrote:Very nice work Petebass, will their be much internal bracing needed to stiffen it up?
Yep I will brace it, but I'll go into that more when I actually do it.
thebman wrote:lovin that front port, I remember reading a TB thread about the option of reversing the front panel layout of a 2nd cab so the tweeters are next to each other when cabs are stacked together. Hope that makes sense. Is their any benifit in doing that or is it simply aesthetics.
No it's not just abut aesthetics. They do it do reduce comb filtering in the highs... which is relevant for improving your vertical dispersion and therefore your off-axis tone. But but in trying to solve one problem they've created another.... the tweeter is nowhere near your ears. You've got a omnidircetional radiating pattern and it's going pretty much through your legs where you can't hear it properly.

I prefer to keep the tweeters vertically aligned to keep comb filtering at bay, but keep the tweeter as high as possible so it's where I can hear it.
* 2 Stingray 5's (one heavily modded), Ibanez SR805, Ashbory, + more...
* Carvin B1500, Epifani PS1000, Ashdown Superfly amps.
* Lots of DIY neo/lightweight cabs including one made from composites http://www.ozbassforum.com/viewtopic.php?f=5&t=2546

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PilbaraBass
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Re: DIY Speaker cab and experiment.

Post by PilbaraBass » 13 Mar 2010, 08:35

I see in one of the pics a foot wearing a flip-flop. Let's use closed shoes in the shop, if you can help it.
No sense in getting hurt. :)

A safe shop is a healthy shop :thumbup:


Nice work, Pete. I like the location of the tweeter. What are you using for a notch filter?
'98 Carvin AC40, '07 Squier JDAV, '91 P-bass, '96 Ibanez ATK300F, '15 Ibanez SR605
Kanye West wrote:My greatest pain in life is that I will never be able to see myself perform live.

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Petebass
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Re: DIY Speaker cab and experiment.

Post by Petebass » 13 Mar 2010, 09:02

PilbaraBass wrote:I see in one of the pics a foot wearing a flip-flop. Let's use closed shoes in the shop, if you can help it.
No sense in getting hurt. :)

A safe shop is a healthy shop :thumbup:


Nice work, Pete. I like the location of the tweeter. What are you using for a notch filter?
That's my father-in-law's foot.... think Gibs from NCIS except he's ex-airforce instead of navy. They even look alike. So imagine what happened when I told him to go put on some decent shoes... he just stared me down and told me to get back to work :)

The notch is just a standard RLC Parallel filter designed for a 6dB peak reduction at 2.5K. It's basically a capacitor, a resistor, and an inductor wired in parallel to each other. It's then placed in series on the positive wire of the speaker wire. For testing I'll probably add a toggle switch so I can turn it on and off. I'll take pics later.

The alternative filter is a simple 1st order LPF - an inductor in series. I figure the main difference between neo's and non-neo's is the reduced inductance cause by the smaller magnet. So in theory adding inductance should tame the mids. Too simple perhaps, and 1st order filters aren't common because they "can" cause phase problems, but that's usually when there's more than one speaker producing frequencies in that band. That's not an issue on this design, so it's worth a try.

Ok I'm going out to the shed now to do some more speakering..........
* 2 Stingray 5's (one heavily modded), Ibanez SR805, Ashbory, + more...
* Carvin B1500, Epifani PS1000, Ashdown Superfly amps.
* Lots of DIY neo/lightweight cabs including one made from composites http://www.ozbassforum.com/viewtopic.php?f=5&t=2546

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Petebass
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Re: DIY Speaker cab and experiment.

Post by Petebass » 13 Mar 2010, 16:18

Only a little bit of progress today:-

first off, here's a pic of the notch filter for Pilbarabass:-
Image

Today I braced the cab. As mentioned, Most commercial cabs use 15 or 18mm ply but no bracing. I use 12mm ply to save weight, but brace it for strength and to eliminate unwanted panel vibrations. I’ve seen bracing jobs that add more weight than was saved by using thinner timber. I’ve settled on what I call “Crucifix Bracing” i.e. bracing that’s basically a cross in the middle of the cab or as in this case, at the weakest point of the front baffle. Not only does this link the opposing panels together as normal bracing would, the point where the cross intersects is glued and screwed so as to create a link to both adjacent panels as well. In other words, the front baffle draws on the stiffness 4 panels at the same time: itself, the back panel, and BOTH side panels. This in effect gives my 12mm ply the same strength characteristics as 48mm ply would have, more if you factor in the strength of the brace itself and the direction of the forces being applied to the adjacent panels. As you can see that’s far superior to 15 or 18mm ply with no bracing. I intend to brace the composite cab the same way, even though Zac deemed it unnecessary. And the best part is the bracing adds so little weight my scales could barely tell it was there. The glue, bracing and screws added a mere 200grams in total.
Image

Next I used a router to round off the edges, once again using a bit designed specifically for this with a roller guide and a 6mm radius. I did take a pic at the time but the camera didn't seem to save them properly and those pics are corrupted files. Sorry about that. But you can see the rounded edges in the pic below.

Image

I got so excited I forgot to add screws to strengthen the joints (I'll do that tomorrow) and rushed straight to wiring the cab up for some preliminary testing. Turns out I made a mistake wiring up the crossover and wasted some time fault-finding, then re-wiring it. The tweeter sounds excellent, but to my surprise it will need to be attenuated. The 2.5K mid hump will definitely need to be smoothed out. I tried both notch filters briefly and they both did a good job - I'll need to do more testing to decide which I'll use.

I put the cab on the scales as you see it in the last pic. On top I placed a metal grill I've got lying around from an old Trace Elliot 2x10 I not longer have, the carpet I plan to use, and the corners I plan to use. The whole lot weighed in at 12.1kg.

More tomorrow.
* 2 Stingray 5's (one heavily modded), Ibanez SR805, Ashbory, + more...
* Carvin B1500, Epifani PS1000, Ashdown Superfly amps.
* Lots of DIY neo/lightweight cabs including one made from composites http://www.ozbassforum.com/viewtopic.php?f=5&t=2546

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PilbaraBass
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Re: DIY Speaker cab and experiment.

Post by PilbaraBass » 13 Mar 2010, 20:32

Pete,

thanks for showing the filter. simple and effective, which is what I like.

I've always wondered why companies didn't go with a brace, again, simple and effective.

Was wondering, with a brace if it would be possible to go with even thinner ply on the sides & rear (leaving the 12mm ply on the top, bottom and front panel). have you attempted such a thing?
'98 Carvin AC40, '07 Squier JDAV, '91 P-bass, '96 Ibanez ATK300F, '15 Ibanez SR605
Kanye West wrote:My greatest pain in life is that I will never be able to see myself perform live.

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Petebass
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Re: DIY Speaker cab and experiment.

Post by Petebass » 14 Mar 2010, 06:52

PilbaraBass wrote:Was wondering, with a brace if it would be possible to go with even thinner ply on the sides & rear (leaving the 12mm ply on the top, bottom and front panel). have you attempted such a thing?
I've contemplated going with 9mm ply and bracing it, but I've never actually tried it. The only problem I can see is that the timber is now so thin that the screws I currently use would split it as they went in, even if I pre-drilled the holes. I'd either have to use a thinner screw and hope it bites with enough strength, or ditch the screws all together and hope the PVA glue alone is strong enough to hold it all together.... which I believe it would in normal use but I don't know if it's survive the accidental fall out the back of a truck with glue only.

Even at 12mm, care is required not to split the timber every time you drive in a screw. Pre-drilling is a must. And if I drive the screw into the centre of the panel as is natural instinct, the head of the screw hangs over the edge of the cab by a mm or 2. So I have to drive the screws in slightly off centre and away from the edge of the cab.

Maybe it's a talent thing but if I'm already making adjustments for the timber thinness at 12mm, I'm going to struggle big time with anything thinner.
* 2 Stingray 5's (one heavily modded), Ibanez SR805, Ashbory, + more...
* Carvin B1500, Epifani PS1000, Ashdown Superfly amps.
* Lots of DIY neo/lightweight cabs including one made from composites http://www.ozbassforum.com/viewtopic.php?f=5&t=2546

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LimeB
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Re: DIY Speaker cab and experiment.

Post by LimeB » 14 Mar 2010, 12:35

You could do a whole seperate ( or have you already ) on a guide for Non tech typres, to make the cross overs / notch filters and what they should do.

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LimeB
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Re: DIY Speaker cab and experiment.

Post by LimeB » 14 Mar 2010, 12:36

Any tips on squaring the peices when gluing and clamping them together ?
What sort of screws?

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