stevie

I've been a bit busy with work recently, which is slowing the project up, but I managed to fit the drivers to Phil's cab and measure the in-cab impedance of the bass driver this morning. The tuning frequency with our 100mm diameter x 120mm port is around 58Hz. We need to get it lower and I've already planned for that. Those of you familiar with WinISD might like to enter the parameters of the Celestion Pulse 10 to see what's happening. The impedance curve is a useful troubleshooting tool, which tells you a lot more than just the load the driver is placing on the amp. Notice the bump just above 2kHz, which was there when I measured the impedance in free air. That's the main breakup point of the cone. There's likely to be some irregularity in the response here, depending on how well the manufacturer has managed to damp the resonance - if at all. There's also a faint bump at about 350Hz. That's caused by the vertical standing wave inside the cab. It looks better than I'm used to. The most interesting - and unusual - bump is at 60Hz. I have a good idea what that is but will have to troubleshoot it. Any suggestions?

That question opens up a big can of worms, @martyy. Yes, at a pinch, you could use it as a PA speaker. However, cabs used for bass guitar normally take into account the extra bass response you get from using the cab on the ground. So it will sound bass-light when used on a pole in the air and you'd need to eq it accordingly. The design goals of this project are not the same as a PA speaker, where the midrange is the focus of your attention. Remember also that this is a budget project. The Basschat Mk III cab was designed with no compromises in the midrange (expensive compression driver, low crossover frequency, good system power response) and works really well as a floor monitor or a PA speaker (in the latter case with the necessary LF eq). In fact, before lockdown, a group of us compared it with an active RCF cab and agreed that its reproduction of voice was superior. I'll be testing the finished design using all kinds of material, including full range audio - and I'll report back.

Sounds like an interesting project. You could probably keep the cab the same size, as the few litres that the amp would take up won't be a problem. You'd just have to alter the port length slightly.

You'd have to watch for vibration and air leaks. Otherwise, it might be worth a try.

One of those grilles would work fine. It's a cheap solution and protects the cone, but does look a bit home made. The round grilles made from punched metal, i.e. with small, round holes, look a lot better (if you can find them) but are more expensive. There's enough space on the baffle to fit a picture frame for a cloth grille. Then there are the metal grilles from Ebay mentioned above. I had real problems getting the etch primer to stick on the aluminium one - I tried two different brands. Although heavier, steel grilles are easier to finish with the type of spray paint that goes straight onto metal (Hammerite, Platikote and the German discounters' specials when they're available).

That's interesting. What I haven't mentioned is that builders have the option of making a tweeterless version, or building in two stages and adding the compression driver later. So a cab built from this plywood with just the 10-inch driver should weigh between 8 and 9kg, depending largely on the weight of the grille.

Thiele Small parameters of the Pulse 10 checked and they're in line with the manufacturer's published data, bearing in mind the temperatures and the fact that the driver's still not fully run in. I also ran a free-air impedance curve and there are no nasty surprises. First main resonance is at just over 2kHz, which isn't unusual. When I have the cabinet, I'll be able to compare the modelled LF response with the actual measured response.

6 minutes ago, Happy Jack said: Any recommendation as to who to buy these from? I'd get the Pulse 10 and Celestion comp from Lean Business and take advantage of their free delivery. Blue Aran don't stock Celestion but they're selling the B&C horn for under a tenner. Both companies are good to deal with. https://www.lean-business.co.uk/eshop/ http://www.bluearan.co.uk/

I've got a Celestion CDX1-1070 and a B&C ME10 horn waiting to be installed. That makes the cost of the drivers and horn under £90 in total. Total weight comes in at under 4kg. The benefit of using these drivers is that they're readily available worldwide. In the UK, the Celestions are available from a number of outlets, but Lean Business are currently offering free shipping on Celestion. The horn's available from Blue Arran. No free shipping, but you can pick up any bits and pieces (like cabinet corners and feet) when you order the horn.

The back is normally a single separate piece. It might make sense just to replace the back piece. Or you could just paint the bare wood black and ignore it.

Soldering is obviously preferable, but there's a good chance the crossover and wiring could be configured to be solderless - using spade connectors and a terminal strip, for which you'd just need pliars and a small flat screwdriver. It depends on how the crossover turns out. Keep watching.

I believe Phil is making good progress with the cabinet, which will be our starting point, and I'm expecting to see the cab assembly details on here before too long. The 10" driver we'll be using is the Celestion Pulse 10. I gave it an hour of 30Hz sine wave in open air to soften the suspension, but my first efforts at measuring the Thiele Small parameters were thwarted by the cold weather. I've had the driver warming up in the house for a day and will try again later.

Well somebody was bound to comment. You were just the first past the post.😊

😊 Yes, he would.

Thomas Eich says those drivers were engineered to work together.

I have in mind something with more excursion - like the 12CL76, but neither of those B&C drivers will have much bottom end in a 30-litre cab. If you model them, you'll see that they have less than the two Beymas - and Phil was specifically going for a bass-light cab. It depends what your goals are (price, weight, size, output , bass extension), but a 10" system might make more sense in a 30-litre cab. There's also a wider choice of bass guitar drivers available in that size.

It's something of an adventure for us, too, John. When you start a project like this, you can never be 100% sure it will work out. Selecting and modelling components based on spec sheets is one thing, but it can prove trickier in practice. For example, sometimes the technical info supplied by the manufacturers is somewhat optimistic - or plain wrong. I recently received a high-end driver from a prestige manufacturer that had a 6dB half-octave dip in the frequency response that wasn't shown in the datasheet. My experience with Celestion has been that their spec sheets and info are accurate. But we'll see. Another unknown is matching compression drivers and horns. Some combinations simply don't work well together - sometimes even components from the same manufacturer. I chose the driver/horn combination based primarily on cost/value for money- so fingers crossed that it works out. The crossover is probably the biggest unknown. Some driver combinations can be made to work together with very simple crossover circuits, while others need more complex crossovers. As I'm aiming for a very simple crossover here, there's no room for extensive driver tailoring - so we need to start with drivers that are well behaved, which I hope these ones are. However, all will be revealed in due course.

I do hope those last two posts are not going to set the tone for this thread. 😁

I think there are better options for bass guitar than that particular B&C driver, including the more expensive drivers in the B&C range. The main problem, as Phil mentioned, is the lack of excursion due to the short voice coil.

So what's the point, I hear you ask? Well, apart from keeping you busy in whatever spare time you may have, this project will give you the satisfaction of having made something useful with your own fair hands during this awful pandemic - because nothing beats plugging your instrument into a piece of equipment that you've built yourself. Well, not much anyway. The cab we're putting together will be small enough to use for practice at home. It will fit easily under the piano or in a spare corner of a room. And if you'd like it to be really spouse-friendly, paint it white or the same colour as the walls. It's an ideal cab for rehearsals or in your home studio - just paint it matt black and leave it where you plan to use it. No need to keep dragging your usual rig in there. If you'd like to use it on small gigs, paint it with Tuff Cab and fit some corners and feet and a handle. For bigger gigs, build a second one without the tweeter. The cosmetics and external appearance are completely in the hands of the builder. There are lots of options. Phil is building the cab we'll be working on in half-inch plywood, and that's obviously ideal, but I suggest using whatever you have to hand. If you have a sheet of chipboard or MDF in your garage, use that. You'll only need a few tools, which I'd expect most people have at home already. A jigsaw, some woodscrews, wood glue, screwdrivers, a soldering iron. If you haven't got a soldering iron, Lidl were selling one recently for under a tenner and may have some left. You can get one from Toolstation, Halfords, etc. for under ten pounds, too. Everyone should have a soldering iron.

This project was touched upon in another thread. We're designing a bass guitar speaker cab that literally anyone can build. Cabinet assembly is based on Phil's easy-build 12" cab, which some of you have already built. This time, we're going to show you how to build a compact bass cab that you can use at home or for smaller gigs. It uses a 10" driver plus a compression driver and horn. It will be designed to be as easy as possible to build. It will also be surprisingly inexpensive, considering that we're using good quality components. Those of you who built the BC112 Mk3 will know that Celestion were very supportive of the project. They are helping out again by providing engineering samples of the drivers. So, thanks once again to Aiden McFall, Celestion's European sales manager. And they've arrived. Edit: Drawings now added here as requested. Please note that you will need to fit an additional batten vertically between the cutouts for the horn and port. This is not shown in the drawing but proved to be needed after testing. BC 110T v1.2.pdf

I haven't seen any info on the Celestion drivers. Has anyone seen inside these boxes yet?

A bit Marmite then.

Looks like it. It's the NXT range without the tweeters. Vintage-inspired indeed.