RichardH

13 hours ago, stevie said:

I would expect there to sufficient clearance (but I haven't checked specifically and will do later). It should just be a matter of swapping the top and bottom panels.

Don't worry Stevie, we can check ourselves. So long as there's no design issues with having the handle at the bottom then we can give it a go. Obviously the relevant damping will be fitted to the panels which ever way they go up.

I'm sure there will be clearance, I wasn't sure if it would have an effect on the wadding. Sounds like that shouldn't be an issue though - thanks for the reassurance!

One thing that may or may not be worth taking off to a separate thread until sorted.

The "sub" cab will need to be set upside down so the two 12" drivers are as close as possible. This makes the handle positioning a bit interesting. I had thought to just build the cab as designed with the handle on top, but add feet to that top surface so it could be plonked down upside down. A bit of a bodge maybe, but I wasn't sure if having a handle impinging on the wadding down by the 12" driver was a bad idea, so thought it best to keep things as standard... 

8 minutes ago, stevie said:

@RichardH, how did you cut the port hole?

Roughed out with jigsaw, then spindle sanded to the correct diameter. This just shows what gear is needed to do a good job - it makes the flatpacks a no brainer!!!

1 minute ago, stevie said:

While Chienmortbb was here this afternoon repairing my coil winder, we alpha tested the BCcab 112 with  a "sub" (same cab but with a lowpassed 12" bass driver). It was impressive. I had been concerned that the bass might sound excessive, but it wasn't in the slightest. It didn't sound like there was any more bass, but the overall sound was bigger (no surprise) and the bass was tighter (which was a surprise).

I guess this will be a project for the New Year.

 

Sounds like my build could be a good guinea pig for this, Stevie... 

Bit more progress on the cab build....

Rough cut for the baffle holes

Making the port hole the right size...

...yup, it fits

One baffle done... 

...which is then used as the template for finishing the second.

...and there we go

I am still intending to run the second one without tweeter, but since I have two horns I thought I might as well have the baffle cut for them, and then seal the horn instead of fitting the compression driver. If I then want to run them as separate cabs or for keys or something, it will "simply" be a matter of another driver and crossover.

I bought the horns ages ago (as well as the two drivers) - I suspect if I'd held fire and read the comments from people who have them up and running, I might have just gone for one cab, but hey ho!

Yup, got to be tan!

Sorry, my browser somehow managed to re-post my previous post from a couple of days ago - please remove!

Wow - that's cheap!

Especially for that budget, you're looking secondhand I suspect - so if you could go to 2U there would be more options.

1 hour ago, stevie said:

Indeed. It's the first build I'm aware of that's based on the plans rather than the CNC kit. Perhaps not surprising, as Richard is responsible for producing the plans that appear on the parallel thread.

I wouldn't say responsible - I took what had already been done and adjusted/amended to suit - I'm just the monkey - never the organ grinder!

1 hour ago, stevie said:

Piano is a much more exacting test of sound quality than bass. You can get away with a lot with bass guitar, but keyboards - and particularly piano - reveal shortcomings  fairly quickly. It's not that you can't hear the the shortcomings with bass, but piano makes them more obvious.

I knew there was a good reason I took up bass rather than keyboards...

I bet these cabs would be a great basis for a Helix + power amp setup either with guitar or (of course) bass.

In other news, my cab building journey has finally begun - although in a slightly disjointed way. I had managed to buy some poplar ply from Mike Walsh (Zoot bass) - who has stopped building the Purple Chili cabs to allow him to focus on building basses. He had a sheet or so of poplar ply left over, and sold me the ply with the basic cuts done for me. I moved house this year and have now (finally) got a lovely shed (albeit without lights and power yet) - but other priorities keep getting in the way (redecorating, rebuilding etc) that for some inexplicable reason according to other members of the household (ahem) should take precedence.  

Anyway, Mike has taken pity on me, and has offered to put the cabs together for me. I should stress that he is doing this as a favour to me - he is NOT going to make any of these cabs commercially, and doesn't have much left in the way of the poplar ply anyway. Stevie's flatpack kits are a much more sensible way to go!

Mike has some odds and ends of hardware left as well, so there may be a couple of cosmetic differences (connector plate, different feet etc), but the important stuff (port, drivers, wadding etc) will be to Stevie's spec. The ply is going to be 12mm in the main (as that is what he had left), though with the baffle done in 15mm. I'd originally intended to do it in 12mm but with a 12mm baltic birch baffle, but since there was a bit of 15mm poplar available, then that will be used. Of course this also means that the dimensions of the panels will need slight adjustments.

I had always intended to build a pair of cabs, but one is going to be without tweeter. Stevie has recommended that when used together, the tweeterless cab should have a low pass added at around 500Hz, so there is little or no interference between the two boxes. We'll see what happens there when we get further along the road.

Superb! 

4 hours ago, Chienmortbb said:

...I set up my amp as I usually did, adjusting the master volume to what was, by ear, my normal playing level. To my surprise the soundman asked me asked to turn UP. Although the sound on stage was as I liked it, apparently it was too quiet FOH.....

I wonder if that is because you could hear yourself better on stage, whereas normally you would have to be louder, hence your FOH sound was relatively quieter to previous exploits. 

13 hours ago, Chris Antram said:

I also need to find a good local (Sussex) tech as well - it could probably do with a service and my AH600SMX certainly needs a service.

Our guitarist has recommended Michael Still in lancing. Apparently very good and all the studios in Brighton use him,as does BIMM.

13 hours ago, Chris Antram said:

I'm just the other side of Lewes

Well hello there! I'm just outside Ringmer! Can't be any tech help, but thought I'd just say hello to a local

On 21/10/2019 at 10:24, Chris Antram said:

2 - I'm starting to understand a bit more about valve amps compared with solid state and the importance of impedance. With my existing AH600SMX I know that it's ok to run one of my 8 ohm cabs or both of them despite amp stating minimum impedance of the speakers must be 4 ohms. However, am I right in saying when a valve amp states 4 ohms it is not a minimum and must be directly matched? In other words I could only run one cab if it were 4 ohms, but as both of mine are 8 ohms I would have to run them together (they're wired in parallel hence 8 ohm + 8 ohm = 4 ohms)?

On 22/10/2019 at 12:26, Deedee said:

With regard to cabs, I too had some confusion/concerns when using valve heads. However as long as you are using at least the same or higher ohm cab/s there will be no problem although you may not be as loud i.e. using 1no. 8ohm cab with your amp switched to 4ohms won't be an issue

I must admit, I thought the impedance on valve amps needed to be matched to the speaker. This being because each impedance output on the valve amp is a different secondary on the output transformer...which would make the original query's statement correct. ...but I could well be wrong, and am happy to be corrected by those who know better! 

1 hour ago, stevie said:

I'd be interested to hear builders' experiences with etch primers - which work and which don't.

Many moons ago I made some cases for my hifi from aluminium sheet and plate. I used an etch primer I bought in Halfords (can't guarantee the one they do now is the same though!), which seems to have worked a treat - the satin black I finished the cases in is still good 10 years on - though of course they don't get the beating a cab (potentially) gets. The one I used was grey, and had a very matt and quite rough surface (almost like a very fine sandpaper) - I assume to allow the top coat to bond properly. So I suspect if a black etch primer is similar in texture, the surface would not be the nicest finish. 

I was admiring the floor tiles

Why not just have a thread for advice - those who don't want to read it can ignore it, but it may well be useful to others thinking about building etc.

Separate threads for each person's build sounds like the way to go IMO - easier to follow progress that way.

Most of the DIY sheds have a section with various profiles like that - usually at the end of an aisle with them all racked up end on. Wickes are usually pretty good for that sort of thing too.

10 hours ago, stevie said:

Very nice shed. I'm envious. I can recommend LED battens for the lighting.

Thanks - this is what it replaced - the benches were chipboard and completely banana shaped from water getting in through the roof - in some places water had worn right through the chipboard (though it was quite atmospheric working in there with the rain hammering on the tin!)

Yup - LED lighting strips FTW - still waiting to get power over to the new shed (it's a bit further from the house, and to be honest the way the power was fed to the old shed made me scared!). 

13 hours ago, Christine said:

You really don’t want a bench to be too wide unless you have a specific reason for it. My working surface is only 450mm although I have a 250mm tool well behind it with a further 200mm surface behind that too incase I need the width but in 40 years I only ever have a handful of times. With a narrow bench you can do stuff like clamp something to it from the rear so it’s out of your way and things never get to far away so you have to stretch 

Very good points. I was intending the bench to be fixed to the wall (which is currently the open 4x2 studwork of the shed itself - I had intended to put ply or pegboard on the wall behind it to stop stuff falling behind), so options for clamping from the other side would be tricky, but I might make some sort of accommodation for that, as it sounds very sensible.

I think the main reason for not using worktop (which is in 3 approx 1.5m lengths) is that I read comments about it being hard to clamp to because of it being slippy - but that's easily fixed with some matting. It will do for the first attempt anyway - I can always rethink if it doesn't work out right.

The comments about height are helpful too - thinking about it, at my old place I put the bench in at "worktop" height, and it was hard to bear down. 

Well, you can't build anything else until you have a bench, right?

Having moved house earlier in the year, we've had a lot of jobs on the go.... and a nice space for me to tinker in has been fairly low on the agenda! Anyway, we now have a reasonably weathertight shed/garage in place (about single garage size - 3.6m x 5.8m external dims), so I'm now looking to get some shelving in there and - most importantly - a workbench. No car will be in there - just the ride on mower etc.

I have some decent sized offcuts of laminate worktop (650mm deep), and had thought to use those as the bench top - any reasons not to do so? Should I be looking to use double thickness 18mm ply or similar instead? Any recommended depth for the bench - is 650mm too shallow? I'm intending to run the bench along from the single side door under the window to the far end. 

I made some cases for my home built hi fi amps a few years ago, made from aluminium sheet. I used an etching primer from Halfords to spray it - followed by a satin black spray. It worked really well, and has been solid over the last few years - but it obviously gets a lot less in the way of knocks than a bass cab.

I was going to say - aluminium grille with the grey cab would look great. That finish you've got looks really nice - very "pro PA cab".