LawrenceH

The gap-filling is only an issue if you have gaps... more of a problem on the more complicated BFM horn designs I'd have thought, as they incorporate lots of angled cuts which are tricky to get accurate on a DIY set-up. Don't over-think it, especially if screwing the cabs, it's just wood glue! I'd just use whatever I had to hand, as long as it's not pritt stick it'll be fine

I have used a UK-brand expanding PU glue, can't remember which but there are plenty available that are gap-filling and suitably strong. Probably this would work (woodwork, geddit? Oh dear) http://www.wickes.co.uk/Evo-stik-Polyurethane-Wood-Adhesive-310ml/p/227825 I have to say though, assuming cutting is accurate and cabs are being screwed together anyway, I have gone back to good old PVA because it is far less annoying when you get it all over the place!

Cheap circular saws from B&Q or similar are crap, I know as we went through 3 of them working up in price progressively and they were all more or less junk - too much flex in the body and footplate so they simply don't stay true when cutting ply over a long length no matter what guide mechanism you use. I now have an old black and decker from the 90s, with a blade that cost about the same as the saw, and it is acceptable. But the big saws in B&Q and the like are far more accurate. In general cheap tools in the US are so much cheaper than here, it's just silly. Make the DIY equation value equation very different for one-offs

[quote name='Magic Matt' timestamp='1410365239' post='2548616'] The local timber merchant stock Birch Ply. I asked if they stocked "void free Baltic Birch or similar" and got this as a quote... 12244122BIRPLY 12mm 2440 x 1220 Birch Plywood BB/BB £31.49+VAT [/quote] That is a decent price in my experience. I've never seen birch that was voided enough to worry about, presumably it's a bit silly wasting expensive birch to produce nasty gappy stuff.

Going back to the port thing, what muddies the water somewhat is that though there is some concern about output compression, more often people's main empirical test of size is based on unacceptable chuffing noise. Not the same thing (though related), and though lots of people report marked improvements in relation to chuffing, I'm not really clear as to what effect the flares have on output level of an otherwise undersized port.

[quote name='Chienmortbb' timestamp='1406117220' post='2508451'] To the three musketeers, My comments were not meant as a criticism just advice. I hope I did not upset anyone. [/quote] Not at all I'm sure - and I think we were in agreement anyway I just wanted to spell out first that driver choice places limitations on flexibility of cab response unless you are able to use complex filters beyond any conventional bass amp, and second that this could actually matter even quite low down. Consider the difficulty of EQ-ing a typical EBS alignment design to flat with a simple filter, even within the nominal passband you will not do it and will typically get a lumpy response when boosting bass. This limits a lot of PA drivers that IMO would otherwise be great for bass guitar, and indeed probably still would be if you had suitable DSP. The nature of the transition to true 4th-order roll-off in a ported cab does matter and there are often advantages to doing it out of passband, which have to be weighed against potential efficiency losses. This isn't just a theoretical issue either, there are plenty of bass and PA cabs out there tuned with a noticeable 'knee' in the low response curve and this does make them more problematic to EQ to a room in my experience.

I still think the limits imposed by the shape of the LF transfer function on the bass end are being ignored, or at least not given much priority. The only practical way of making eg a Vanderkley sound like an Acme in the bass would be with DSP filtering, regardless of xmax/power limitations, because the EQ on even quite a flexible amp won't be able to sufficiently compensate for the difference in cabs to give a similar overall roll-off curve. This is another reason to think carefully about tuning in the 40Hz versus the 50Hz regions, since tuning lower can give a curve that is easier to EQ within the range you actually care about using the EQ controls found on a typical amp (eg 12dB/oct shelving filters for the bass).

Worth remembering that set points for filters are typically -3dB (or even -6). So even if you hear a difference with (say) an 80Hz filter, it's probably as much to do with the signal at 80Hz and up being attenuated rather than below this. Steeper filters allow you to cut lower but can be harder to integrate than shallow slopes, unless it's a true subsonic filter like those built into power amps.

Not familiar with that model of Laney and can't see the pic well enough to tell, but a lot of those mixer/amps are mono, if that's the case here then a 8 ohm plus 5.5ohm would drop you below the minimum and overheating would be a real possibility. If the amp is stereo then ignore this irrelevant contribution!

What they should do, right, is build the micro amp into the speaker cab itself. I'm a genius! Patent office here I come...

This 'hybrid resonator' description is as clear as mud. Puts me right off when a manufacturer goes all marketing-speak. If it's a low-tuned ported cab why not say it? Or if it's something else like a passive radiator then why not say that? Or if it is something like a hybrid port/ transmission line (ie a system where standing waves are not minimised) then say that, though that would be ironic given what I remember of Alex's previous contributions to threads on TL speakers for bass guitar. There is a bigger irony in the evolution of barefaced products back toward the higher qts-style midbass bump, since that was exactly the type of sound so roundly derided when BF first started. But it is a good sound

Xmax is 8.8 calculated Faital-style. But it's all a bit academic beyond a certain point as different speakers will behave differently with large signals and this is hard to quantify in a single figure even with sophisticated Klippel-type analysers, better to use your ears. I have said to Phil et al previously, that I think the response in the low-mids plays a big role in how people feel about a speaker, along with the shape/frequency of the resonance peak. Noticeably the Beyma charts show a dip around 300Hz, something I very commonly replicate by EQ as a sound engineer, since it's just a region where you get a lot of wooliness in real-world spaces, and it's also roughly the region where you get a scoop with e.g. Markbass VPF - removing some here often helps clean up or 'tighten' the sound. I will be interested to see if this element of the mf response chart is replicated in Phil's design. It could be a good thing for a lot of players in my opinion, but it'd be interesting to see how a player whose sound is very focused in this region felt about these cabs. Another issue that's rarely touched on when people get focused on design using T-S-based simulator programs etc is the role of baffle step in the real-world frequency response, which is very problematic to deal with once speaker cabs exceed a certain size, since it becomes so intrinsic to the space. When is 'flat response' truly flat? It's easy to get too hung up about things like modest bumps eg in the midbass, whereas if you saw what any cab response looked like in-room from a particular listening position, you would just give up in disgust! Yet our ears adapt

I think Phil's point earlier, that modern speakers are actually less efficient, is very significant not just in terms of the issue of why we seem to need 'more watts' these days, but for the implications this has for the sound of modern bass guitar.

If you've got it in a ported cab already try stopping up the ports and see how you like the sound - Phil's right about the roll off but with micro amps packing hundreds of watts, you can just boost the bass to compensate and it might give you a good practice cab. That speaker should take it. The good thing about this approach is it's free, quick and fully reversible

If you want more overall volume, but not necessarily more true bass, then I'd think about using as big a diameter driver as you can cram into whatever box size is suitable for your transport needs, ie moving from 8" to a high-sensitivity 10" (or to 2x8" if the slimmer form-factor makes it more convenient). Bigger radiating driver area makes more of a difference than just increasing the wattage input but keeping the driver the same.