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stevie

12" Cab Diary Continued

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Here are the corrected versions.

2dgpdlf.jpg&key=285cfe1449bc4f28c7420f8a95cec7aef865e524d76f8ddde4b583a61a8cc84d
2h80oe9.jpg

Edited by stevie

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[quote name='stevie' timestamp='1490950284' post='3269264']
I'll give it a go. I've just tried three other highly recommended drawing programs, but they're not as intuitive to use as Paint. I just need a copy-and-past feature so that I don't have to draw everything from scratch, and the ability to save text as text, so that I can edit rather than erasing and re-writing.
[/quote]

For simple diagrams I use Google draw: https://docs.google.com/drawings/

It doesn't have schematic symbols, but it works well for basic layout diagrams.

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Paint doesn't have any symbols either; I just drew them as lines or rectangles. It would have been nice to have been able to copy and paste them once I'd drawn them once, or to move them if they weren't quite in the right position. Google Draw does look good, but I found that I can do what I want with the Open Office drawing application. But many thanks for the pointer, 6v6.

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[quote name='stevie' timestamp='1490965068' post='3269449']
Here are the corrected versions.




[/quote]One of the things you will notice is how complex the crossover is. Not that I want to put anyone off building it but compared to some of the best commercial offerings this is a beautifully tailored circuit.

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I was up at 7 this morning as time is running out. The wadding is in and I have glued the top and bottom. The glue sets fairly well in 2 hours but clamping time is 4 hours so four hours it is. That will be about 11:30 when the edge corner shaping and painting will be done, I have to be out for the afternoon (more pressure) returning about 18:00. While the box is drying, I will make the crossover.

I have had trouble posting the template drawing for the horn, when converted to an image file the size is wrong so you need the PDF. I have now posted it and you can get it by clicking [url="http://candheat.co.uk/documents/PH170.pdf"]HERE[/url]. The drawing is a very zoomed version of the small image on the P--Audio data sheet. Although slightly pixelated, it is accurate to within about 1.5mm and using the cropped rugby ball shape in the middle, I cut a template that made a good hole as can be seen in the baffle image in an earlier post.

The complete P-Audio data sheet for the PH-170 Horn is [url="http://www.p-audio.co.uk/products/P-Audio_PH-170_1_inch_Throat_High_Frequency_Horn.php"]HERE[/url]

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That template will prove invaluable. I found it really tricky (i.e. messy) to cut the oval shape out on the prototype and wish I'd had it them. I think it needs to be pinned to post #1 so that all the reference documentation is in one place.

[Edit - I just tried to pin it, but it looks like no more than 3 PDFs can be pinned to any one post. We'll consolidate all these files when we're done.]

Edited by stevie

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Well after burning the Midnight Oil and getting up early I just about managed to get the Cab to the Big Fat South West Bass Bash. I had about 5 mins to check the cab at home before setting off so it was a leap of faith to think that I had connected everything correctly in the crossover. I just knew I had noise of sorts coming out of both drivers. The handle was not on , there were no cabinet corners and Heath Robinson would have been ashamed of the crossover construction but it worked.

We had about an hour comparing the my MK2(.5?) with Phil Starr's MK 1 cabinets. I think Phil will agree that you could hear the difference but it really did prove what a nice driver the Beyma SM212 is. Out in front (where the audience would be) the difference was noticeable but not massive. However when standing above the cabs, in "gigging" position, the improved dispersion was quite noticeable. This was the main design criteria for me. To be able to hear myself, without a monitor, when there is no FOH support. A number of people said they would be happy to gig with Mk1 or Mk2 even though they owned high end cabs themselves.

We tried to record the cabinets but the "war of the bassists" made any meaningful comparisons very difficult. Hopefully we can get some real sound clips and other opinions soon. sadly my guitarist has a damaged nerve (no not his brain) in his left hand so no gigs for me until June but I will tidy the cabinet up and keep using it until then. At some point I will take it to Stevie so we can measure its performance to see how close it is to the prototype and the original design goals.

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Well done for getting it finished and to the bash - that's real dedication for you!

At some point it'd be really interesting to know how close this is to the original weight estimate. I have a hunch, based on my 18mm poplar Mk I cabs, that it might have turned out a bit lighter than you thought it would.

Note that I deliberately avoided a straight "How much does it weigh?" question - that'd only invite someone to come along and ask if it's any good for metal B)

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I will weigh it when I find my luggage scales but here are some pics of the almost finished cab. I am still debating whether to pain the port black but I am starting to like the contrast so it may stay. My dad used to tell me that you cannot hide blemishes with paint and it is true even with TuffCab. I have some screw holes to fill and a bit more sanding OR I might just spend the time playing through it.

Edited by Chienmortbb
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[attachment=242254:ASHDOWN PICS (7).jpg][attachment=242247:Ashdown MiBass 1 X 12 Lightweight Cabinet.doc][attachment=242247:Ashdown MiBass 1 X 12 Lightweight Cabinet.doc][attachment=242257:ASHDOWN PICS (2).jpg]

Hey guys seeing this is a 1 x 12 build, I thought I would show you what goes on in the little Ashdown cab. Sorry about the quality or the photos.

Michael

Edited by The Shrek

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[attachment=242258:ASHDOWN PICS (4).jpg][attachment=242259:ASHDOWN PICS (14).jpg]


Some More Pics. Not a lot of bracing or sound deadening inside this one !

[b]Ashdown MiBass 1 X 12 Lightweight Cabinet[/b]
[b]Specifications:[/b]
[b]Power Handling[/b]
250 watts
[b]Speaker Configuration[/b]
1 x 12" Driver + HF Horn/Tweeter
[b]Speaker Outputs[/b]
Jack
[b]Impedance[/b]
8 Ohms
[b]H x W x D [/b](mm)
545 x 390 x 365
[b]Weight [/b](kg)
16

Edited by The Shrek

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I could estimate it: 7kg wood. 4.3kg Beyma 12. 1kg Celestion compression driver and horn. 2-3kg crossover, handle, feet, grille, paint. It should be under 15kg anyway. Going neo would take that down to about 12kg. But let's see what John's scales say.

The grille works well but I think it needs some piping to finish it off. Perhaps carpet would be an easier finish than paint for the occasional builder. I wonder.

Edited by stevie

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That's interesting, Shrek, thanks. I have to agree with Bill Fitz on this: manufacturers tend to be more interested in how a cab looks than how it performs. Love the crossover!

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That's so right Stevie. Someone like myself who knows nothing about crossovers and tech stuff, will look at the little cab and think of it's portability, size and looks. if it sounds okay then we are happy, not realising how crap the build is and the use of inferior components. But it is a cheap cab so we can't be too critical. I had two Eden 2x10 xlt and an Eden 1x15 and a WT 550. Great sound but they were so damn heavy . I had a groin hernia repaired 4 weeks ago and I think I know what caused it ..lol

Michael

Edited by The Shrek

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[quote name='stevie' timestamp='1491228308' post='3271352']
The grille works well but I think it needs some piping to finish it off. Perhaps carpet would be an easier finish than paint for the occasional builder. I wonder.
[/quote]


Speaking as an occasional builder, I did a pair of bass cabs in Tuff Cab and a guitar combo in tolex last year and found the Tuff Cab to be a lot less work. Though my bass cabs were in birch ply which should be harder and denser than the poplar used here - maybe that makes it easier to achieve a good surface?

[quote name='stevie' timestamp='1491228824' post='3271359']
That's interesting, Shrek, thanks. I have to agree with Bill Fitz on this: manufacturers tend to be more interested in how a cab looks than how it performs. Love the crossover!
[/quote]

I can see a cap and resistor but no inductor - what's going on with that? Is that a piezo tweeter?

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Along with my earlier 2 x 10 build, I built another 1 x 12 cab to the exact specs of my little ashdown cab. Now I am going to finish it and I want to port it with a single 4" round port rather than the slot port, is this feesable?

I then found the basschat 1 x 12 build and started following. Could I use the Beyma 12" you guys are using? Rather than a tweeter I want to use a 5" for mids and fit a proper crossover which I thought I could buy of the shelf. (a little knowledge is certainly dangerous..lol)

Once again any help would be appreciated. When I started my builds I foolishy thought that you made a box the same size as a commerically built cab, then you could just stick a speaker in and it worked. I didn't realise the science behind it all.

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I think carpet is easier to fit and also more forgiving than tolex, BoB. The lesson here is that you really have to finish off your screw holes properly or else they show through the paint.

It looks like they managed to do without the inductor. :)

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[quote name='stevie' timestamp='1491231499' post='3271392']
I think carpet is easier to fit and also more forgiving than tolex, BoB. The lesson here is that you really have to finish off your screw holes properly or else they show through the paint.

It looks like they managed to do without the inductor. :)
[/quote]

I think the hair and dirt attracting properties of carpet have always put me off. Too many memories of the drummer using my old Peavey as a rolling mat, or picking off hairs and thinking "Well, I [i]hope[/i] that's just a beard hair"!

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Shrek, yes you should be able to use a round 4" port instead of the slot port.

The Beyma we're using should work in your cab, yes. I performs fine down to a cab volume of about 40-litres. It would be worth copying some of the details of our cab and transferring them to your build, in particular the bracing and the wadding. No need to follow slavishly; just follow the principles.

Using a midrange unit is a great idea, but you will not be able to do anything worthwhile with an off-the-shelf crossover. It needs to be custom-designed for the specific drive units. You should have enough room in your cab for the P. Audio tweeter - and the x-over isn't that complex. If you're going for the Beyma 12, you could give it a try.

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Ok Just North of 14Kgs with only a handle (150gm)and a few more corners. I will be filling the screw holes either dowels an I have enough TuffCab left to paint another couple of coats.

Edited by Chienmortbb

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Thanks Stevie. Guys I hope I am not being forward in asking this question. I would gladly pay upfront for the service if there are any of you basschat guys who would be prepared to build a proper crossover for my project. Just advise me on what speakers to buy to match the appropriate crossover build. I am in Northern Ireland so I will gladly pay for any excessive post and packing and any other costs.

Michael

Edited by The Shrek

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I seem to remember Phil saying he was thinking of doing a 40 litre cab using the Beyma. As for the screws, I finished the cab a bit too fast enable me together me to get to the bash and had to cut some corners. I am now going to replace the screws with dowels then re-applyTuffCab so the final effect will be much better. I also agree about the piping Stevie the whole effect is s bit too dark at the moment.

Does anyone know where to get it?

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[quote name='Chienmortbb' timestamp='1491250436' post='3271625']

Does anyone know where to get it?
[/quote]

I've had it from Solsound on eBay - I think they refer to it as Marshall piping. You might find your grille frame is a tight fit with piping though - I made mine a few mm undersized to leave some clearance for it. The other thing that might look good is a thin metal angle trim around the edge of the grille. HH used to do that with a very similar grille material to yours.

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[quote name='Chienmortbb' timestamp='1491168216' post='3271026']
Well after burning the Midnight Oil and getting up early I just about managed to get the Cab to the Big Fat South West Bass Bash. I had about 5 mins to check the cab at home before setting off so it was a leap of faith to think that I had connected everything correctly in the crossover. I just knew I had noise of sorts coming out of both drivers. The handle was not on , there were no cabinet corners and Heath Robinson would have been ashamed of the crossover construction but it worked.[/quote]

Well done. I've seen wet paint and partially cured glue at too many GTGs and trade shows to even count all the times any more. More than a few have been my own builds too.

Personally, I really like the all dark look a lot, and never really liked plastic piping or trim of any kind except for corners, same as on basses for that matter.

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!4 kg is good, my originals came out at around that without the horn and crossover, though my bracing internally was a bit agricultural (rushed for the last bass bash) and I used Baltic birch rather than poplar.

Yes I'm looking at doing a 40litre version, possibly even smaller as I might do some prototyping with a bit of spare ply. Basically I find I always end up dialling in a hump at 100Hz and rolling off below 40 anyway, the response you'd get in an over small cab. That's fine with my Harke amp with a graphic but is proving harder with my Mark Bass amp. I'm wondering why I'm carrying extra wood to not quite get the sound I want.

I'm also getting more interested in the pschoacoustics side of things, what actually makes up perceived bassiness, punch and, dare I say it h**t. With Stevie currently chasing FRFR cabs I might look at voicing in cabs. If it goes to plan then I'm going to have a go at a lighter cab with better bracing first (Stevie did a much better job than I did of damping the panel resonances), I may even look at other drivers if I'm feeling flush.

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