stevie

[quote name='Al Krow' timestamp='1499369228' post='3331141'] A wider question to my fellow BCs: does the wood used in the cab construction have any bearing on the quality of the sound a cab puts out or is that pretty much entirely down to the speakers, electronics and drivers? [/quote] Yes, the wood makes a noticeable difference to the sound, as does the quality of construction and cabinet design. It's only part of the equation but quite an important one. Let me give you a tip. Next time you test a bass cab, play an open E (doesn't have to be loud) and feel for panel vibrations with the palm of your hand. The back panel is likely to be the most telling, although it depends on the shape of the cab. If you can feel vibrations at a low volume, imagine how much that panel is going to be vibrating when there are 400 watts slamming into it. Whenever I go to a Bass Bash, I spend 15 minutes or so testing cabs for vibration (I don't think anyone's spotted me doing this so far) and it's been quite illuminating. You won't be able to feel any vibrations with a well designed cab and that translates into better dynamics, better transients, lower colouration and less "lumpiness" at volume.

[quote name='ebenezer' timestamp='1499248344' post='3330224'] Love the engineering and thought that go into barefaced cabs, but i could not live with something built out of 9mm plywood !..... [/quote] 9mm (poplar) ply would put me off too. Weight-saving is all very well, but I'd prefer something a bit more substantial both from a practical and acoustical point of view. Having said that, for some players, weight is the number one priority. So I can see the attraction.

Only just seen this..... First you need to unsolder the coil. There are two wires coming out of the coil. Unsolder the wire still connected to the board and also the piece of broken wire. If it's the outside wire on the coil that has broken, just pull out a piece of the wire from the winding, scrape off the insulation at the end, tin it and solder it back in place. If it's the inside one that has snapped off (much more likely), it's a bit more difficult. You will be able to see the very end of the wire that has snapped off poking out of the coil former. Your mission, should you accept it, is to undo about one turn of that wire from the inside of the coil so that you can resolder it to the board. Use a very thin screwdriver to ease the wire out enough to be able to grab it with some snub nosed pliars. If that proves too difficult, use your snips to cut the plastic bobbin so that you can access that bit of wire and pull it out. Cutting the plastic won't do any harm. Also bear in mind that the insulation on the wire is quite tough, but don't go mad. I've done this loads of times. Good luck! Oh yes - glue the coil back with silicon sealant and a couple of tie wraps. Otherwise the same thing will happen again next week.

OK, good. The resistors won't get hot enough to damage the ply. A couple of tips for crossover assembly. Use non-ferrous screws, brass or stainless steel, close to the coils; anything ferrous will alter their value. Use silicon sealant to glue the components down. Unibond Power Extreme also works well but is a bit pricey unless you can get the Aldi version. Don't use heat glue; its shear strength is poor and the heavier components will become detached if the cabinet is dropped. Use cable ties generously.

[quote name='RichardH' timestamp='1497441141' post='3318144'] That sounds a good way to do - I had been thinking of using the phenolic sheet. The eyelets idea is genius - that way you can pass leads though the board rather than keep it all on the surface. [/quote] There is no wiring on the surface. The layout is as it would be for a regular printed circuit board, with all the component wires passing through holes in the board and then being hardwired underneath the board (instead of being connected by PCB track). The holes at the right hand side of the tag board are where the wires come back up through the board to connect to the tags. I think a photo would have saved a lot of confusion here.

Incidentally, Richard, I have sheets of blank PCB board fibreglass in my workshop, but I still find it easier to use 6mm ply. It doesn't look quite as "pro", but that doesn't really matter.

Excellent! That would be very helpful.

I'm used to designing and using proper fibreglass PCB boards, but they do need to be produced in quantity. I've experimented with a variety of materials for one-off builds, and 6mm ply and tag board is the best solution I've found so far. 6mm ply is also very cheap, but the problem is getting hold of small pieces. Wickes and Homebass sell a 1200 x 600mm sheet for about a tenner, and I'm sure there must be wood merchants and joiners prepared to sell smaller sheets of offcuts (my local DIY shop does). Anyone building their own cab from 15mm poplar ply could use offcuts of that. Homebase also sell a 1200 x 600 sheet of 6mm MDF for £6.

The port tuning was always going to be 50Hz.

The .56 and .18mH coils are close enough, but don't waste money on thick wire for the .17mH. - 7mm or thereabouts is fine. All the coils are air cored.

When you upgrade your speaker there is always a chance that you will have to enlarge the cutout, especially if you're going from a pressed steel to a cast chassis. Check the hole size in your cab and the cutout sizes in the driver spec sheets to see. If it's an RS112, bear in mind that the bass driver contains a tweeter, which you will lose if you change it. But if you only use it under another cab, I'd suggest the following. For a budget option, get the Celestion 12" driver currently for sale in the classified section of this site. Without knowing exactly what's currently in your cab, I don't know how much more you'll get from the Celestion, but it could be enough. Next up would be the Beyma SM212. This is a really nice upgrade long-coil driver that a few of us already have good experience with. Good value at about £80. If you want better, look at the Faital 12FH520 - a 600W high-end neo driver and probably the one used in the top-of-the-range Vanderkley. £650 in the Vanderkley but about £160 on its own.

Luke, the two designs for the Mk II are complete. There is a low cost version with a tweeter and a more advanced version with a compression driver. They both use the same cab, but that's it. Chienmortbb assembled the more advanced version and I measured it to make sure everything worked as intended. When I have time, I'll try to post some building guides in post #1 - but everything you need should be contained in the thread. If not, please ask. The cab is based on the use of 15mm poplar ply, which I thought would provide the optimum balance of light weight and strength, and this has indeed proved to be the case. There is, of course, nothing to stop you using another material, but if you want a proven lightweight design that will outperform 90% of equivalent commercial cabinets, go for the poplar ply and compression driver.

I've attached a PDF to post #1 showing the crossovers for both versions of this speaker. I am about to assemble my own version of this box (500W neo driver with expensive 1" horn) and will try to make a photo record of each stage of assembly. I don't think this cab is difficult for anyone with basic woodworking skills to assemble, but a step-by-step guide might help. Richard, if you would care to take some photos of the crossover you assemble, that might help, as I suspect building the crossover is more of a challenge to many people than building the box.

I'll see what I can do, Richard. The crossover information for the first version of the speaker is on page 4.

The drawing you need is the crossover for the Beyma SM212 and the P Audio 407 tweeter, which is attached to post # 1 of this thread. I did try to add the more complex crossover (for the Celestion compression driver) in the same place, but there seems to be a limit to the number of PDFs you can attach to one post. You can get all the parts from Blue Aran, although I doubt they will have every value in stock. If you have problems, send me a message and I'll see if I can put together a package with all the components for you. For the tag strip, look up "solder tag terminal strip" on eBay. The current link, which may change over time, is: http://www.ebay.co.uk/itm/2-x-36-way-Solder-Tag-Terminal-Strip-on-Paxolin-Bakolite-Board-2-Strip-/132211098217?hash=item1ec8654269:g:MvgAAOSwBLlVfzCU Just as a matter of interest, I did originally design a simple crossover with just a few components on the tweeter and nothing on the bass unit, which is the de facto configuration on most commercial cabs. However, the slighly more complex version with a few components on the bass unit sounded so much better that I didn't even bother mentioning it in the thread.

I can't make it to a pub gig with my blues band on Saturday 17th. Anyone like to stand in? I can send a set list and some recordings, but the songs are fairly standards blues numbers. Please get in touch asap.

The big problem with research is that it has the capacity to reveal things you would rather remain ignorant of, or don't understand, or don't know what to do with. A tricky one.

Yes, that's a really useful comparison, although when he goes into more detail it gets a bit confusing. The most useful information is in the first minute. Although I've owned the SPB-2 and SPB-3, I never liked them much and have always stuck with the SPB-1. I don't hear anything from the more expensive Antiquity that would make me change either. Maybe another brand, but I think Duncan got it right the first time.

Our singer couldn't stretch that far either (unfortunately) but it's not a bad idea to know what to aim for.

The Altos are unbeatable for the money, but you owe it to yourselves to audition the RCF ART712A. Twice the price, but worth the difference if you can afford it.