stevie

Another benefit that occurs to me of going with rounded ports is that altering the cabinet volume becomes a lot easier than with a slot port. It should be a fairly simple job to recalculate the port lengths for a (slightly) smaller box using the usual free software.

On the matter of cutting the holes for the port tubes, I bought an adjustable hole cutter recently for less than a fiver which may not be the last word in pro tools, but will do the job perfectly well. It might take a few tries on some scrap pieces of wood to get the size spot-on, but it's not too difficult to do. http://www.ebay.co.uk/itm/Handy-Adjustable-Metal-Hole-Saw-Round-Circle-Cutter-DIY-Tools-Accessory-/252069704389

I agree with the standing wave explanation. The addition of the slot port makes the internal vertical and horizontal dimensions fairly similar, which will further reinforce the standing wave which, as tauzero points out, is at the frequency you would expect from those dimensions. As we don't have this problem with the round port version, I'd suggest that we follow Luke's pragmatic approach. Another benefit of the round port option is that a tweeter could easily be substituted for one of the ports if desired - either straight away or at a later date.

VERY nice work! Thanks.

If you want a rough guideline, using neo magnets will cut the weight of a speaker by around 50%. You'll save more on heavier, more powerful speakers (10kg down to around 4kg for an equivalent driver) and less on more modest drivers. 4.5kg down to 2.5kg, for example. My neo speaker weighs 3.7kg and the manufacturer produces a direct ceramic equivalent weighing 9kg.

You wouldn't happen to have any more of these, would you?

Excellent effort - I really enjoyed that. The singer fits in really well.

Have just done a swap + cash deal with Roberto for my Markbass LMIII. The deal was concluded quickly, with no messing and we both sent our respective amps off the next day. Roberto was a pleasure to deal with and I can only apologise that my amp arrived a day or so after his. Deal with confidence!

Yes, well spotted, although 1% is not a lot and it is a very narrow peak. I wouldn't expect it to be audible. Having listened to some similar cabs on the web, I'm coming to the conclusion that a flat frequency response cab can benefit from some tonal adjustment to get the particular sound you're looking for. Also, quite a lot of cabs seem to 'bake in' a boost at 100Hz, which has the subjective effect of making the lower mids less prominent.

[quote name='Jenny_Innie' timestamp='1446391548' post='2898995'] Then there was a letter that went out to all owners offering a kit to fix the issue. Basically, a pot of glue with a plastic spreader tool. [/quote] It's good to know that in this day and age customer service is alive and well.

[quote name='Hobbayne' timestamp='1446199021' post='2897605'] A few years ago, I saw the Bootleg Beatles in Liverpool. [/quote] Whooooaahh - that's uncanny!

[quote name='LukeFRC' timestamp='1446163191' post='2897493'] have you got a commercial bass cab to hand that doesn't sound prominent mids? I wonder if you measured that and your cab side by side you would be able to see on the charts what the other cab was doing that made your build seem "middy" [/quote] I'm afraid not, Luke. I've only got my own 15" - but that also measures flat and doesn't have the bark of this 12. So I'm a bit flummoxed. Having a well-thought-of 12" cabinet for comparison purposes would have made life a lot easier. Those simulations you linked to mostly show speakers with a falling response towards the midrange. The Basschat 12 doesn't do that, but it's easy enough to produce that kind of sound balance with your preamp. When I pull the 500Hz area down with my amp, I get 'my' sound (not a Trace smiley-face sound - I like plenty of mids). So I don't want to over-emphasise this.

[quote name='EssentialTension' timestamp='1446147872' post='2897379'] Some people said the same about The Eagles themselves. [/quote]

I know some of you guys play in tribute bands, but I wondered how many of you have seen a band called the Dutch Eagles. I've never seen any other tribute band come as close as they do to recreating the sound of the original band. Not only do they have the music and the voices down pat, but they have the accents down too, which is rather an impressive feat as they are singing in a foreign language. [media]http://www.youtube.com/watch?v=6d1SbC0Jly4[/media]

Indeed! You were in fact the one who made me write "near unanimous". It's so easy to be bamboozled by what you hear - measurements are more reliable most of the time. Except that I'm still hearing prominent mids from this cab, which the measurements are not showing. Pulling back around the 500Hz mark takes out the "boing" overtone that I've also heard with some other 12" cabs. I was going to calculate a filter to put a notch in the frequency response, but as nobody else seems particularly bothered, I'm going to leave it alone.

Sounds like a plan. I've often used the Beta 12 in PA cabs before because it handles voice very well, but I've no direct experience of it with bass guitar. I wouldn't really expect it to come close to the Beyma - but it is quite a bit cheaper.

Just a final note. I've modelled what you'll get with a variety of other popular bass guitar drivers in this cabinet: These are: Red: Beyma SM212 Orange: Kappalite 30120HO Yellow: Faital PR300 Blue: Celestion BN12 300X Green Eminence Beta 12a Apart from the Eminence, which exhibits mild peaking at 100Hz, the others are very close below 200Hz in this cabinet. Naturally, there will be differences in the midrange and in matters such as power handling. As I have an Eminence Beta 12a here, I measured its response in this very same cab. I have to say, it looks rather good.

Although this is only at a few watts, the distortion measurement is still very impressive.

Here's the impedance curve of the slotted port version. The cab is tuned to about 46Hz, a bit lower than the first tube-ported version.