stevie

The hole for the other horn proved to be slightly too big, but some fibreglass filler came to the rescue. In the drawings, which Ghostbass is very kindly reworking for us as we speak, the horn is located more centrally on the baffle, as that is acoustically the best place for it. I also decided to position it vertically to improve the dispersion to the player's ears when standing up close to the cab. So - the handle is fitted and I've foamed the grille support. This is what is looks like with the grille. Although perhaps I should say, that's what it looks like under flash. So I took the cab outside and took some more pictures.

Since I last posted on this thread, there has been a change of plan on the drivers. I struggled to get the cab sounding right with the original horn and decided to revert to the P. Audio horn I'd used previously. I haven't given up on the asymmetric horn and may revisit it later. However, as the design objective of this particular version of the cab is light weight, I thought that the combination of the P. Audio horn and a Celestion CDX-1415 compression driver would be a good choice. The total weight of the 12" bass driver, the Celestion compression driver and the P. Audio horn is just 3kg. Amazing! So even though we've used 15mm ply for the cab, a proper crossover, and a metal grille, the total weight of the finished product is 13kg. I'd call that a result. It was difficult to get a decent photo of the compression driver with my cheap camera and flash, but it really is dinky - weighing in at just 250 grammes. It's not cheap, but it does have a 1.4" voice coil, and not a 1" coil like cheaper compression drivers.

We resume our little story after the cab has had two coats of Tuffcab paint. Time to sort the grille out. I was fortunate enough to obtain an Ashdown 2x10 cabinet with blown drivers, whose grille proved to be an ideal fit. But first I cut some 15 x 12mm pine strip to make a grille support. A coat of matt black paint, and I had this: The observant among you will have noticed that the port is no longer grey. The grey port looks quite good in actual fact - it's distinctive - but I thought I'd paint it black anyway, as I had paint in my garage that was unlikely to be used for anything else. It worked fine, as you can see. I did have to cut the grille to size with my ancient, trusty metal-cutting shears. .

Altering the compressor setting on my RM500 head also alters the overall volume. I wish it didn't but I just set it to 12 o'clock and leave it.

Wow - that's excellent!

I guess you have to be German to play Bach then.

Yes, I appreciate that, Paul. Sorry for the thread derail but I was asking the question for my own information.

This will sound daft, but what if I just want to record from a microphone into the laptop? I don't need a DAW and don't need to equalise, have separate tracks or anything like that. Just a straightforward recording. Like plugging a mic into a tape recorder and pressing the red button. I have a high quality mic and a USB soundcard with a built-in mic preamp. What software should I use? Does Windows 7 Sound Recorder work?

Just bought a strap from Pete. Excellent service and the item was exactly as described. Thanks Pete!

Sounds good. Shame you can't fit a 100mm port in there, but you should find the 75mm one an improvement on what you have. I wouldn't recommend you keep the small port, but you can always experiment and it's your choice. To get the tuning frequency for the port arrangement you have now, I split the difference between your original port tuning and what a 75mm hole would give you. I wouldn't bet my life on it though.

A bit of patience isn't a bad idea when you have a saw in your hand, Doug.😀 Anyway, I'll try to explain what's going on, although none of this is 100% reliable as I don't have the cabinet here and I'm relying on the accuracy of your 37 litres measurement. When I checked the tuning of your cab with the 50mm port, it worked out at around 42Hz. That's normally too low, and I expect the port wasn't doing very much at all - even ignoring the fact that it would be compressing very early. By cutting an 80mm hole, you have tuned the cabinet higher, to just over 60Hz by my rough reckoning. That would normally be too high, as it would seriously reduce power handling at the lowest frequencies, but the combination of greater port area allowing the ports to do their job more efficiently and the higher tuning frequency means that the ports will now actually be producing useable sound. So you should be hearing a difference, as you clearly have done. When your plastic port arrives and before you seal up the55mm hole - and make sure it's sealed solid - you could compare the cab with the 55mm port and with the 75mm port by blocking each one in turn with a t-shirt or similar, and having a listen. You should then be able to hear the difference between the old and the modified cab. I had the impression originally that there wasn't much free space on the baffle. So my question now is - would there be room on the baffle for a 100mm port in place of the 75mm one? But please don't go sawing any more holes until we measure what you have now. For that we need a frequency sweep generator and some rice. Although maybe you've now had enough DIY.....

I don't think he was thinking of building a cab, Phil. There's an Ashdown 1x12 for sale on here at the moment for £100 which could be a good investment for Doug. If the combination doesn't work, he can always re-sell without losing much, but I expect he'd be quite happy.

A second 5.5cm port would be a good idea, yes - but you'd then have to extend the length of each port, including the original one. A single 7.5cm port would be better if you can fit it in.

It's likely to be worse. You can easily try it out by stuffing a t-shirt in there to block it up. You'll then have a sealed cab. As long as there's space on the baffle and you don't mind a bit of DIY, you could upgrade the performance of your existing cab by making the port bigger. The driver itself doesn't look half bad. You can buy plastic ports cheaply to give the hole a professional look. One of these would enlarge the port and tune your cab to the same frequency you have now: <https://www.bluearan.co.uk/index.php?id=TUFFBR75&amp;browsemode=manufacturer> You'd probably still need a second cab though.

37 litres is about the smallest useable volume for your typical 12" bass guitar speaker. The big stumbling block is the 5.5cm port, which will compress and make noises at a very low level. Try playing a low E through it and listen. Because the size of the cabinet plays a huge part in determining the efficiency of the system, you can't really make a cab more efficient just by sticking another driver in there. The efficiency at low frequencies is determined almost entirely by the size of the cab. I think your best option is adding a second cab.

I couldn't swear to it, but I seem to recall that when Bass Gear Magazine measured the Markbass LMIII it was flat with all the tone controls at noon. Cabs aren't normally flat though, and your settings are probably compensating for your cab and the room.

Good sight reading practice. Ho Ho. I don't think I could ever play that in a million years.🤩

Love it! I've always wanted to have a bash at that Real Thing line.

Did he write that? Well I'll be blowed.

At the beginning you say that you "work from the top knuckle" rather than bending your fingers - then you proceed to play with curved fingers throughout the video. I think it's great that you're putting lessons online, but I think you need to fix that.

That sounds like a good deal to me.

Try and stop me!

Aha! No, but I know a smartalec when I see one. 🙂

Too right! I was too much of an idiot to figure it out and sold mine.

The big question is why you want a custom-designed cab.