6v6

I've got a Lm3 and never noticed any fan noise tbh, I do mostly use it in a band though. I can try to measure the volume in a home environment later.

It's a real personal taste thing, but FWIW I'd perhaps go all gold on the tuners without any black, as there's already a lot of different wood colours etc going on, so I think it might look a bit cleaner and draw more attention to the wood?

I'm interested and planning to build one of these, crossover details would be great as I've not had time to try modelling it (was planning to have a play in LTspice but an overview would be most helpful, my EE skills are rusty!). FWIW I think the question about combining Mk1 and Mk2 cabs was a good one, and I appreciate the clarification as I was wondering the same thing.

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!

Nice diagram and detailed design, great work folks, thanks! I think I'm going to have to build one of these to see how it compares to my current SM212 loaded cabinet My SM212 is from early 2013 - was there a spec change for newer drivers? I seem to recall something about that, so wondering if I'm better getting a new one for this build, or can I safely switch the existing driver between cabinets?

Honestly I think any of the jointing methods will be OK unless the cab is abused - I used biscuit joints on my build primarily because it makes it far easier to align the panels vs plain butt joints (although the cleats to reinforce the joint Phil suggests would also be a simple way to do that without any special tools). I agree dowels/biscuits on a lot of low-quality ply is a bad idea (the core is often full of voids and very weak), but if you make the effort to find good quality void-free birch ply it'll probably work fine with any of the methods mentioned, particularly when you consider the strength added by securely attaching (ideally glueing) the back of the cab and the baffle.

Can you link the circuit diagram you're working from? Hard to comment on the component removal without seeing a schematic but it sounds like the capacitor was part of the tone stack, I'd expect to replace it with a different value vs just removing it.

Interesting build! I think covering the cavities and making them airtight will be enough to fight feedback (thinking of an acoustic guitar soundhole bung which works by sealing the cavity not filling it) but I doubt foam inside would do any harm

[quote name='T-Bay' timestamp='1484256062' post='3214172'] Sadly eBay is full of complete and utter morons these days. [/quote] This - I've given up selling anything on eBay because every other transaction turns into a fiasco like this. Good luck in resolving it!

The LC15 is a guitar amp though, so I'd probably take it easy on the volume when using it for bass, even if you do have a higher rated bass specific speaker. The reason I say that is the transformers in a guitar amp are quite often under-rated compared to an equivalent power of bass amp, with output transformers this can work out OK as it adds a compression to the sound, not so much when power transformers run too hot as eventually they fail. As others have said though, the amp/speaker combination should work

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

Fwiw I made my sm212 loaded cab (similar but not same design as the bc 12) with an adjustable shelf port and gigged with both 50 and 41hz tuning. IMHO the 50hz tuning handled the lows of my 4string bass better and I did provoke a few ugly sounds from the driver with the lower tuning. So I also don't think it will necessarily help to tune lower unfortunately.

Eminence already publish plans for this driver, so you could just pick one of these designs: http://www.eminence.com/pdf/Basslite_S2010_cab.pdf All you'll need to do is calculate the box dimensions based on the volume in that - you could use the dimensions of some popular commercial design as a starting point, then tweak it to match the exact volume and port dimensions described in the eminence document.

My LM3 went up in smoke (standard fan) so personally I'd be very cautious of replacing the fan with anything that's not moving the same or more air, and I'd be VERY cautious of using a switch to turn it off Without internal monitoring it's going to be very hard to tell when things are getting hot, and it only takes a short time for the power amp to get wrecked (mine was replaced under warranty, I think it melted one or more output transistors, lots of acrid smoke, fortunately at a practice not a gig, but it wasn't being run hard at all when it happened).

I tried this once with an old traynor 4x10, it pretty much fell to bits after I ran the saw through it (cheap osb board and stapled together without much glue). Whole thing ended up in the bin! I'm sure this is possible but I'd say you're better off selling unless you're sure it's solid ply construction where you can get some good strong joints with battens, screws etc on the new wood. Then there's the finishing to consider, which will be hard to do neatly unless you re cover both boxes completely.

Potentially yes, it's a tube design so will have capacitors inside which may stay charged at high voltage for a while, even after it's unplugged. Personally I wouldn't open it up without a multimeter to carefully measure the residual voltage in the power supply before putting my hands inside.

Fantastic result, looks great!

[quote name='Andyjr1515' timestamp='1476900839' post='3158331'] Looks splendid. I'm attempting to make a pickguard shortly. I find them a right pain! Do you have any tips and tricks? [/quote] Well this is the first one I've attempted, but the approach I took was to make an mdf template, double stick tape the plastic to the template, then use a flush trim bit in the router table (got a cheap one from aldi!) followed by a chamfer bit to cut the bevel. Worked pretty well but I had to experiment with the depth of cut on some scrap to get the bevel looking right. I suspect the same approach would work with a hand held router, but I'd probably make a thicker template so it could be stuck securely to the bench without the bearing fouling, and possibly add a sacrificial thin mdf board on top to avoid marking the plastic with the router base. There are some pretty good tutorials of the router table method on YouTube which is how I figured it out, good luck!

I think this will always be tricky - with a powerful computer and the right interface you can get pretty low latency but it will never be zero and you're taking a risk when recording if you run with really tiny buffers. I think most studios asked to do this would probably patch in the reverb on the desk via an outboard processor, or perhaps be using recording interfaces with dedicated DSP for effects (such as some RME devices), which amounts to the same thing with less boxes.

Looking good, nice clean wiring job! Be interested to see the results of any modelling of the circuit.

Small amount more progress around family duties this weekend, got the control cavity cover done and rebate routed. Rapidly reaching the point where I'm going to have to attempt the paint!

[quote name='rushbo' timestamp='1476634066' post='3155815'] Nice work - I'd be inclined to round off the lower horn of the pickguard, but you've got that three-ply thing down! [/quote] Thanks for the comment - yeah I agree the lower horn will probably see a little refinement with file/sandpaper before final fitment.

Been struggling to find much time to work on this lately, but managed to get the pickguard made:

Looks great, you must be very pleased with how it's turning out! One question - what sort of polyurethane varnish do you use, and does it go off really hard? I finished a build with an oil based polyurethane varnish about 20 years ago (thinned with white spirit and sprayed). It looked good but never quite fully cured, even after weeks I could mark it with a fingernail. In the end I sanded it all off and re-did it with cellulose lacquer, so I'm interested to know what you're using here. I'm pretty sure paint technology has moved on since I Iast attempted anything like this, but I'm about to spray my freaky fretless, and was planning to use all cellulose products, but the result you're getting here is making me question that decision!

Looks great!