stevie

Although not easy to achieve, my experience is that a flat response is desirable because then you know what you''re working with. If you want to add harmonic distortion or colouration, or accentuate or cut specific frequencies to get your sound, that's fine. But if your amp/cab is coloured to start with, you're stuck with that sound and have nowhere to go.

There are some benefits to crossing over actively, but a properly designed passive crossover does a lot more than roll the drivers off at either end and splice them together in the middle. You also have to equalise the bass/mid driver to compensate for the effects of the cabinet and horn as well as the usual anomalies in the drivers themselves and then you have to deal with the phase problems you get from the spacing of the drivers. It can be done actively, of course, but you need to be able to delay the bass driver so that LF and HF arrive at the same time at the crossover point. You may have to apply asymetrical rolloffs to compensate for any intrinsic rolloffs in the drivers beyond the crossover point. And you need to be able to equalise the entire system so that it's flat. If you can do all that, and have the measuring gear to ensure that you get it right, you can certainly use another compression driver and horn. However, sometimes passive is just easier. John is still looking for the circuit for the Beyma 12 and Celestion CDX1-1445 system and is hopeful.

This is how it's done. It's the tightest little beat combo I've heard in years.

I just checked - and I don't seem to have it. The problem is that I kept developing the cab (it was a diary-style thread) and didn't keep all the details of each stage of development. John who is Chienmortbb built one and he may have kept the circuit diagram. I've asked him. Otherwise, the Wayback Machine might help..... Sorry!

Yes, I published the crossover details for the Beyma 12 with a P-Audio tweeter, but since then P. Audio decided to change the diaphragm from titanium to phenolic. I've no idea how much that changed the performance of the tweeter, but it certainly will be different (and very likely worse), which meants that the published crossover won't work properly with current versions of the tweeter. There is a neodymium version of that tweeter with a titanium diaphragm, which I duly purchased to test. Unfortunately, it was nothing like my original ferrite one (and also nothing like the published spec sheet). So I sent it back and gave up on tweeters. The next design mated the Beyma 12 with the P.Audio PH-170 horn and a Celestion CDX1-1445 compression driver. That's a high-performance, low cost combination. I published the crossover too, but it got lost due to Tiny Pic's shenanigans. If it's of any interest, I can repost it.

I can see (hear) why you wanted to change the driver. That's much better!

To me, this is a 250-quid fuzz box - so I'm definitely not the target market. However, I can see the business logic behind the move and I'm sure Alex knows what his customers want. This is a tough time to launch a new music product and I wish him well with it.

All the photos I posted for the Diary Continued were removed when the previously free Tiny Pic hosting service decided to change its business model. I uploaded most of the later ones, particularly those showing how to assemble and finish the cab, but it was not always clear from the context which photos from the earlier part of the thread were missing. So I didn't bother with those. Then there was the fact that P. Audio changed the spec for the tweeter used in the first budget two-way design - I think that was the MKII - and there wasn't a lot of point in uploading those photos anyway. If there's any interest in a design for a budget 12" + horn tweeter, I can certainly do one, based on either the MkIII cab or the less complex but easier to build MkI. However, both of those cabs are perfectly usable with just a 12" driver on its own.

There you go. I actually nicked the idea of panel pins from Chienmort, although the self-drilling screws idea was my own. They sometimes work better than clamps. If you leave the panel pins in, just be careful if you're using a router to round off the cabinet edges.

Nice work! That Beyma driver is a classic and works well in that box. I agree about getting straight, square cuts - it's so important but not easy. If you're short of clamps, you can always use panel pins or self-drilling screws - remove and fill the the holes once the glue has dried.

The bass needs to be more forward. The whole thing sounds like it's in mono. Otherwise, it sounds pretty good to me. I'm no expert though.

I'd be very careful with this if I were you, @B.Flat. There's a very good chance that the lowpass circuit Bill has suggested will drop the impedance of your speaker to 2.5 ohms. Your Yamaha is 2-ohm stable - so you should be all right. However, you should be aware that the circuit will probably also induce a nasty peak at 2kHz, which won't be very nice. Just sayin'.

The cheaper cabs in this list, @stewblack (the first four) all have ceramic magnet drivers. Barefaced also use ceramic magnets. The more expensive ones are fitted with neo drivers, which is what you'd expect. Those Harley Bentons are ridiculously cheap. As a DIY'er, it would be difficult to build a poplar ply cab for those prices - never mind buying the drivers.

I can't imagine that there is a more friendly, better organised bass bash than this. I'll be there!

It looks like an interesting project. However, if you want to by bypass the passive crossover in the BC12 cab you'll need to be able to programme the crossover and DSP. I've no idea if that's possible. Simply bypassing the passive crossover with the Mackie one will not work properly and will definately sound worse (as Chienmortbb has already said). To adjust the active crossover, you'll have to time align the drivers by delaying the woofer. Then set the crossover (24dB L/R) to 2kHz and use the parametric function to equalise the response of the CD horn. If you're going to use the separate 50W amp for the HF, you'd need to adjust the sensitivity to compensate for the higher sensitivity of the HF driver. Even if you can do all this, chances are that the passive crossover will sound better anyway. So I'd agree that connecting a full range signal to the regular input on your cab is probably the best solution. Should be good.

Graham bought a cab from me and drove all the way from Kent to collect it. It was nice to have a chat about basses. Lovely chap and a delight to deal with.

Mark bought a cab from me. He was a delight to deal with and is a credit to Basschat.

There's a lesson in there somewhere.

Agreed. I looked at the 15" cab and the porting is the first thing I noticed. I don't think you can manufacture for those prices without cutting corners. I would imagine that being outside a customs union would make returning a faulty product quite complicated.