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[quote name='Balcro' post='1323688' date='Aug 1 2011, 11:19 PM']The usual response to questons such as yours is to recommend the use of winISD software.[/quote] Just tried it out... nice to see what looks like Delphi software still around. But the problem is it seems to be design rather than reverse engineering i.e. it tells you what you should have not what you have got, you can't adjust port length afaics. What is the Sd parameter? Can't find that for my BN12-300S and can't think what's in m2... It's always interesting to read people's profiles btw ficelles

[quote name='bassman7755' post='1323450' date='Aug 1 2011, 08:15 PM']and possibly even damage the driver through over excursion.[/quote] Which in the event is exactly what happened with the tuned cab by selecting the wrong tuning, although the drivers - while useless for bass now - still work fine in a friend's guitar extension cab. Over-excursion folded the cones at the point of join with the rubber mount but there is still enough rigidity for non-bass use. ficelles

[quote name='LawrenceH' post='1323341' date='Aug 1 2011, 06:08 PM']ficelles, as has been said before a port without an additional pipe is still tuned. The effective port length can usually be considered the width of the baffle with the hole in.[/quote] I know that, it's just my use of terminology - untuned to me means what you get from the basic enclosure with a hole, tuned (in my usage anyway) means you have added something, pipe, shelf or whatever, to tune for a specific frequency. I would do the maths (I might even dig the formulae out of my old acoustics textbooks for fun one day) but ultimately my cabs seem to sound fine "untuned"... I am intrigued as to why this topic has caused such dissent though! Am I right to assume that no-one in here has actually studied acoustics at college or whatever, or more specifically the acoustics of speaker cabinet design? Hands up all those with Acoustics Degrees Not me btw... ficelles

[quote name='Mr. Foxen' post='1323290' date='Aug 1 2011, 05:20 PM']I think would be more to do with poor cab construction than port tuning. Or possibly the hole compromised the structure.[/quote] No, it was the port tuning... I took the tubes out and the problem went away. The cab is very solidly made and the structure is 100% sound. I've actually just been testing it with a tone generator and it's amazing how resonance-free the cab is now (which is more than I can say for my kitchen ). ficelles

[quote name='alexclaber' post='1322743' date='Aug 1 2011, 08:13 AM']And why would you want that to happen? Just curious about the thinking - I think I might write an article about ports soon...[/quote] Firstly because the drivers I was initially using are not recommended for sealed enclosures, secondly to increase low end efficiency & response. Incidentally I initially got the port tuning wrong on my larger cab with the result that it was so resonant an amp wouldn't stay on the top... For both my large and small cabs I now have untuned ports i.e. no pipe... the larger one I currently have vented at the rear, the smaller at the front. ficelles

[quote name='Balcro' post='1322631' date='Jul 31 2011, 11:18 PM']What for you is the purpose an untuned port? Balcro.[/quote] Lets the air out. ficelles

Just wondering what material is generally best for bass cabs? I opted for Marshall-style basket weave for my lightweight 1x12 only to find the darn stuff creaks and rustles at higher volumes and lower frequencies i.e. anything below low G (49Hz and down) Maybe it won't notice in a band context but it sure is annoying when I've tested it cranked up at home... if I can't live with it I think I'll opt for a metal grille front, won't look as good though. ficelles

The metal jacket ones look like early 6V6 valves... I ran one in a THD Univalve for a while. ficelles

[quote name='Bill Fitzmaurice' post='1320736' date='Jul 29 2011, 07:03 PM']The port radiation is only out of phase below the tuning frequency, and in a properly designed cab it's moot as that lies primarily below the speaker operating bandwidth.[/quote] Indeed, but isn't it in phase but a wave behind at and above the resonant frequency? I.e. the backwave phase is inverted by the port so in phase with the frontwave but with a single wave time lag? ficelles

[quote name='Dekker' post='1320607' date='Jul 29 2011, 04:19 PM']Having the incorrect parameters can (and probably will) result in time smearing, and an overall "muddy" sound.[/quote] For front porting don't you get that to some degree anyway? The backwave is inverted but one wave out at the resonant frequency... ficelles

Untuned ports i.e. just a hole... anyone in favour / not in favour? Any rule of thumb for size? ficelles

Judie Tzuke with Morcheeba - Enjoy The Ride. Classic. ficelles

I need to strategically shrink some areas of tolex (yes that's right, sloppy glue spreading), I seem to recall that there is some car interior cleaning compound that achieves this? If anyone can point me in the right direction I will be eternally grateful ficelles

A 4x15? Madness gone mad with an extra dose of madosity. Only someone with roadies would use something like that. Edit: I think Mr F is right though, judging by the width of that HH head it's maybe a 4x12... although those drivers are angled in of course... ficelles

[quote name='TRBboy' post='1319737' date='Jul 28 2011, 08:44 PM']What does everyone recommend as good value for money and not too complicated (don't want to spend much if I can help it!)[/quote] The volume control(s) on your bass. Nothing extra to buy or plug in and generally under-used. Likewise the tone controls. ficelles

[quote name='Bill Fitzmaurice' post='1318802' date='Jul 27 2011, 10:34 PM']That's taking it to the extreme, and what you end up with is a 4th order bandpass. I'd imagine the mids are pretty weak with that one.[/quote] These little things sound stunning with a Precision through them. Not so good with a Jazz. But then I guess you'd probably worked that one out... ficelles

Must have been some kind of communication breakdown...

[quote name='LawrenceH' post='1316247' date='Jul 25 2011, 08:56 PM']That has more to do with the fundamental limitations of 12" speakers than eg the small advantage gained by crossfiring. I'm a big fan of angling speakers back on stands to get the guitardist's ears closer to the 'beam of death' but a neater solution (IMO) is Jay Mitchell's 'foam donut' [url="http://www.stratopastor.org.uk/strato/amps/prii/speaker/foamdonut/foamdonut.html"]http://www.stratopastor.org.uk/strato/amps.../foamdonut.html[/url] Dead simple to implement and the beauty is you can tailor the foam type/thickness and size of the hole to give some flexibility to freq cutoff and amount of attenuation.[/quote] I sense a beam blocker discussion approaching... ficelles

[quote name='Bill Fitzmaurice' post='1316092' date='Jul 25 2011, 06:59 PM']The number one complaint of FOH engineers in 10,000 plus seat venues is stacks. To get eight twelves crunching hard the dB level from a stack can overpower even a 30kW PA at 100 feet, and FOH engineers go mad trying to get a balanced sound when said stacks are cutting a swath like a laser beam on-axis. With PA support no guitar'd player needs more than a 2x12. But Jimi and Pete and Richie etc., etc., etc., used stacks, so therefore... [/quote] I guess history is to blame... big guitar amps developed before big PAs and every guitarist wants the look. Last time I saw Mason Neely (Cerys Matthews) he had a tiny tiny Fender guitar combo onstage and sounded great through the PA. Gary Moore used to have a little Fender combo mic'ed up behind his wall of (unused) Marshall cabs. Word is most of Status Quo's wall of 4x12s don't even have speakers in... ficelles

[quote name='Mr. Foxen' post='1315993' date='Jul 25 2011, 05:33 PM']No, Fender didn't make tall stacks, they made short combos, and guitartists tend to sit on them or stand in front of them, so all the top end misses them and icepicks anyone in front..[/quote] Exactly... back in my sound engineering days I would regularly be deafened in 400+ seater venues by guitarists refusing to turn down their amps... "but it's only 50 watts and I can't hear myself properly"... worst offenders were those of the Hank Marvin school of tinnitus-inducing ice-pick guitar sounds! ficelles

[quote name='markstuk' post='1314945' date='Jul 24 2011, 05:57 PM']It blew the socks off his current Ashdown ABM 1x15/4x8 setup....[/quote] I still have some nostalgia for that configuration, such sweet little cabs! Shame the appeal was more visual than sonic... Here they are with an ABM head as opposed to the Bass Pod Pro bi-amp setup. ficelles [attachment=85555:ashdown1.jpg]

[quote name='markstuk' post='1314937' date='Jul 24 2011, 05:47 PM']Bill is this Bill... [url="http://www.billfitzmaurice.com/"]http://www.billfitzmaurice.com/[/url] He's a fellow home builder :-)[/quote] Torres do some good home build kits here in the UK... not quite as extensive a range as they are focused a little more on amp building, but apart from their standard cabs they will cut panels to order. ficelles

[quote name='Bill Fitzmaurice' post='1314839' date='Jul 24 2011, 03:37 PM']Flawed. One doesn't need four 8s to provide the mids to keep up with one 15; one would be sufficient.[/quote] What a charming response Do you make many friends in here? Anyway it depends how you like your sound, and the whole point of bi-amping is to be able to better tailor the rig to your sound and to the room you are in. And you are forgetting that a consideration is visual - a 1x8 would look pretty silly. You need those 4 shiny cones to highlight just how fearsomely powerful your rig is. Btw my current "large" cab is a vertical 1x10 + 1x12, with a rear slot. Home-built of course. No doubt you can now tell me exactly how and why that's wrong, but it sounds great to my ears and is neither boomy nor weak in any particular frequency band (specific room acoustics excepting of course)... here's a picture of it in action. jayjay [attachment=85543:keynsham.jpg]

[quote name='Bill Fitzmaurice' post='1314768' date='Jul 24 2011, 02:22 PM']AFAIK the only cabs on the market today designed for bi-amping are some G-K, and those are woofer/tweeter cabs, not woofer/midrange, where bi-amping is most useful.[/quote] Maybe it's fallen out of fashion... it was all the rage in the 80s! A few years back I used to run a Bass Pod Pro bi-amp out into a stereo power amp driving (seperately of course) a 1x15 and a 4x8, crossing over around 200Hz if memory serves me correctly. Worked pretty well, but not markedly better than my other rig which was a GK RB400IV into a single vertical 2x10 so in the end the simplicity of the single head/cab won out. ficelles

[quote name='Bill Fitzmaurice' post='1314392' date='Jul 24 2011, 01:01 AM']The logic is sound. It was, and unfortunately remains, the implementation that was flawed. The hi-fi and PA (then cinema sound) guys knew back in the 1940s that you use big drivers for lows, smaller drivers for highs, along with a crossover so that they don't have overlapping coverage. The electric bass cab industry is still in the process of figuring that out. [/quote] Really? As to my recollection crossovers - particularly in the context of bi-amping with different cabs & drivers for different frequency ranges - have been in use in bass amplification for decades. ficelles