Phil Starr

You're right, we did try the 40Hz tuning for the MK1, the 50Hz sounded better and had better power handling over the important frequencies.

MDF sounds better because of the extra mass, the lack of voids and the fact that it is less resonant than ply. However it is less tough, heavy and as has been said can't cope with moisture (beer at a gig) so isn't really practical for a gigging cab. If it is just for home practice go ahead. I'd probably go for 12mm for a single 10, 15 will certainly be enough.

If you want a BV mic then it's worth thinking for a second whether you want a cardioid or super cardioid. the difference is in the pickup pattern but a cardioid is generally much more tolerant of poor mic technique. The super cardioid is better at rejecting feedback. If you are a loud singer that jumps around a lot as I am then the cardioid is the one to go for. If you are quieter and prepared to keep your head still whilst playing bass and singing at the same time then go for a super. The mic to beat is definitely the AKG D5, much better sounding than the SM58 but it's a super cardiod, however they also make a cardioid version the D5C. I've two D5's so I really trust them. The Samson SM58 clone is the Q7, really cheap and incredible for the money, slightly more top than the one it is trying to copy but with a bit more handling noise. The Behringer XM8500 is ok but there is some poor soldering on some I've seen. Easily fixed if you are handy. Don't go for the cheap Shure's, well made enough but the sound isn't good. I've also used the Sennheisers and they are another good sounding rock solid mic but the E835 isn't up to the same standard as the AKG D5 and the 900 series are pricier. If you did want a Shure the Beta58 is a nice thing. Big upgrade on the 50+ year old SM58. Wasting your time, buy a D5

There are two types of people on issues like this, those who want a practical solution to a problem and those who like to tinker and use it as a learning experience. Swapping drivers poses a number of problems, though none of them fatal to the idea. The driver might not be a good match for the cab and you might end up with frequency response of power handling issues if not. A new driver might not match the output of the 212 and contribute little to the sound or it may have a different frequency response and you will lose the character of your TC setup. If what you really want is plenty of power with your sound intact I'd seriously consider selling the 112 and buying a second 212. Tinkering with the 112 will reduce it's value if you cannot restore it to original condition afterwards. Putting the £160 of the quality driver together with the used price of the cab will take you to the used price of a 212 or thereabouts, you'll end up with a matching look and no compatibility problems. Ha ha, just read Bills comment

Every time you ask a simple question it opens up a can of worms I'd copy Stevie's design in your position. I recommended 18mm in the Mk1 for simplicity in the build. Even then I built an 18mm and 12mm cab with more extensive bracing and tried the cabs before deciding which I'd recommend. I preferred the sound of the 18mm cab. Stevie went for thinner material and more extensive bracing in the Mk2. again a lot of testing took place to get a good compromise. Cabinet resonances are complex, you have a lower frequency resonance of the box itself but each panel has it's own series of resonances and I'm looking at an equation which shows a whole series of resonances for a square panel. The factors that determine the frequencies of these resonances are the dimension, mass, Young's Modulus and the speed of sound of the panel. On top of that the volume of the resonances and their decay time are affected by the internal damping or Q of the panel and also the way the edges of the panel are treated. Even a minor change in the glue can affect the volume of some resonances by 10dB. I've also got some practical measurements in front of me and some of these resonances mean the output from the cab matches the output from the speaker meaning the cab is virtually transparent at those frequencies. Cross bracing will kill some of the cab resonance but will usually simply shift the panel resonances to higher frequencies where they may be less or more troublesome. That's not there to put you off though, I suspect few commercial cab designers spend a lot of effort on bracing yet still come up with much loved products. My gut feeling is that unless you want to spend some time fiddling around with bracing a thicker panel is likely to give a better sound.

[quote name='DIYjapan' timestamp='1496757303' post='3313666'] The 57L is with the bracing. Without I was about 62L. As for port velocity: I was looking for that but haven't found it yet on the software. Also went and looked at the SPL running at 250watts. The max of my little Tc electronics BH250. Looks like I may get in trouble if I crank it up. There was a spike below 50hz and another bump over the red line from 100hz area. Worrisome? [/quote] That increase in excursion below the port tuning frequency is shown by all ported designs. I've put up a thread about it which a lot of the techie BC people contributed to. It might be worth a read. It's not a problem if you use a good low frequency filter like a Thumpinator or you avoid boosting those frequencies which are pretty much out of our hearing range and not particularly prominent in the output of your pickups. It doesn't cause a problem for most of us but people do sometimes blow speakers if they are unaware of it and do strange things to get 'more real bass' You need to be aware of it is all. The higher peak, midbass peak if you like is what is causing the over excursion in that area. The 12-A2 doesn't have the super excursion that the better drivers like the 3012HO have. Have a look at the maximum power charts and you'll see there is quite a reduction in the maxumum power. Whether it's a problem depends upon how you use the speaker. There's a little safety in that the safe mechanical limit is 11mm so brief peaks aren't going to damage the speaker. The 12A-2 is pretty reliable for most of us. Long term flat out use with lots of bass boost might cause the speaker to overheat though. Try modelling it in a smaller box and you'll see that the maximum power will increase at these frequencies as it will if you raise the tuning frequency a little.The trouble is that both changes will give you less bass but that might be acceptable. We spent a long time tweaking our designs to get where we did. I don't thrash my speakers and quite like that midbass warmth but that's a personal thing. It wouldn't worry me but it's something to note certainly. If you are concerned it may be worth going for the more expensive driver and a smaller box. The excursion wouldn't worry me

Well done, now you have access to the software you can answer a lot of your own questions. That 3dB hump is fairly typical of a lot of commercial designs. In practice it gives a good solid bassy thump to your sound. It's caused by a lack of damping of the cone at low frequencies. Bigger magnets on the speaker and bigger air masses from having a bigger box will damp the excursion and flatten the curve which is what the Delta and 3012HO will do for you. Hence the rule that you can't have cheap, deep and lightweight. The flatter deeper curve will give you a cleaner more detailed bass but can excite room resonances when used live in smaller venues. That is easily solved by rolling off the bass in most situations. It's worth your while looking at the port velocities and excursion graphs too. Input the maximum power you will operate at and see where your speaker exceeds Xmax on the excursion graph. Limiting the size of the box will give you a bit more power to play with at the expense of a little less bass. If you tune high you usually get good handling down to the tuning frequency but problems below that with excursion. If you tune low then the excursion low down improves but you can get problems in the 80-100Hz region opening up. Don't tell your wife, I can spend hours fiddling to get just the right compromise. the problem with the Delta is that it has an extraordinary spike in response around 1-2kHz (from memory) and the DeltaLF has little midrange output as it is designed to work with a tweeter. Only use the LF if you are going to use a horn. The 12A-2 has a nice peak with quite a wide span which with the bass hump in your model gives the speaker a nice smiley face response curve, the classic old school bass response. Finally that 57litres, have you taken of the volume of the speaker and the bracing? It might have a volume close to 50l by the time you allow for all that.

Glad you've tracked the fault down. Piezo horns are really cheap, as little as £1.00 https://www.bluearan.co.uk/index.php?browsemode=category&category=Speaker_Components&masthead=High_Frequency_Drivers&subheadnew=Piezo_Tweeters The easiest way to seal the hole is to cut a square of ply, or any wood you have to hand, slightly bigger than the hole. Then simply glue it on the back of the hole. You may be able to seal the old horn though with a generous dollop of decorators mastic or even silicone sealant. Use neutral cure silicone though as the fumes from the acid cured silicone (acetic acid, smells of vinegar) aren't too good for speakers. using Stevie's design for horn and crossover will upgrade you speaker though, it's a nice painless project and I can say the results do sound nice.

I'm assuming stands, mic's and leads should be included in that? Any monitors?

Glad I wasn't the only one knocked out by the bassist. Fab tone too.

Hi again Leonard, just to say I'd definitely go with an active speaker nowadays. The advantages are threefold at least, the amps match the speakers and have computers on board (DSP) which will make sure the speakers can't be overloaded no matter what the operator does, a big factor in community use where any idiot can end up at the controls. Having active systems mean fewer leads to confuse people not used to pro PA and at the end of the day they are quick to knock down and everyone gets home that little bit quicker. Going for the bigger RCF speakers means you won't need bass bins, again more appropriate for use by a wide range of potentially inexperienced users. I like the Yamaha's and the EV's too and JBL do good active speakers as well but I've done a comparative test and the RCF's and QSC's someone mentioned are just a little better at the moment. I'd happily use the Yamaha's or EV's if I couldn't quite stretch to the RCF's. Yamaha reliability is legendary and I've used the old passive stuff for years. With the Behringer mixers you suggest they are excellent, but again think about who would have to operate them. Will they be able to navigate the menu systems and take advantage of all the extra facilities if they are unfamiliar with this sort of electronics? A fairly simple analogue mixer is a bit more intuitive even if the simplicity is a bit limiting. Not a complete no no but worth thinking about.

I've been reading this for a while but haven't commented because almost all of the things I'd have said are on the other 12" threads running at the moment, also I think this is more a 'what to buy next thread' than a technical one. There are plenty of people out there with more expertise than me in that area. It seems to me that you are happy with your sound but want just a touch more of it? If so then why not just get a second matching 2x10 for the bigger venues? A 2x10 or a 112 should be enough for anything if you can genuinely put everything through the PA. keeping your own volume down on stage stops the vocal mics picking up too much backline and really cleans up the band's sound. If you can hear yourself with your current set up you have enough and it is better practice to let the PA do the heavy lifting. You can hear yourself now so for this band the set up you have is 'enough'. As to the technical issues. There's nothing special about that TC so the excursion of the speakers is going to limit ultimate bass output, but I suspect from your description of 'distasteful frequencies' that the piezo tweeter may be the problem. If you overload that it is going to be distasteful as it will if you run the amp into distortion at the peaks. As a temporary measure turn it off or down if you can, rather than trying to eq the distortion out. I really don't think the wireless connection has anything to do with it (unless your batteries were flat), my very run of the mill Line 6 G30 actually gives a cleaner sound than a long lead.

Hi Leonard, I have no experience of that particular set up, so this is all from general principles, but with no-one else yet commenting I hope this might help until someone with more knowledge comes along. There are some advantages in this sort of system, easy set up being one which may suit your needs. The other is control of dispersion that the line source offers. Really useful in an echoey building with lots of hard surfaces. I also like moving the crossover point out of the mid-range, which I think improves vocal sound. The downsides are a lack of volume and the expense. For the cost of a single speaker system like these you could afford four reasonable quality conventional speakers or buy a pair of something market leading and have some change for a decent mixer and a set of mics. I'd agree with Mike on the volume issue too. They are advertising 121dB continuous and 129dB peak. The 121dB figure is probably more honest than many ad claims but how they justify the 8dB extra peak is a bit odd. 6dB peaks are the normal permissible manufacturers guff. 121dB won't be enough for a metal band in a 700 seat venue but would probably do the 150seat venue if you buy a pair. That's £3,900 though! With that sort of budget I'd be looking at the RCF ART735, a pair of these will do everything you need in all probability. I don't think you'd need subs at all so just two boxes and no more difficult to set up than the LD's.

Thanks Geoff, I have visitors this w/e. I'll have a look on Mon.

I can do a rough calculation based on that but I need the exact width and height of the port as well as the length to get it right. Check for anything loose whist you are looking

[quote name='geoffbyrne' timestamp='1496255984' post='3310022'] If I pluck a low B and let it ring, I hear it 'fluttering'. The original driver was farting out badly at any decent volume (EQ flat) so I thought I'd try a Beyma in it. Big improvement but, as I said, there's still this 'flutter' that to my uneducated ear sounds like the air pushing & pulling through the ports. (Chuffing?) I was wondering if an exta round port at the back would improve matters? What measurements do you need, Phil? G. [/quote] I want to calculate the tuning frequency of the cab, I have the dimensions of the cab from Ashdown's ads but I need to know how long the port is. It could be chuffing or it could be something loose in the cab. It's very hard to be certain without hearing the cab. It might be worth a quick look to check if any stuffing in the cab is loose or there is anything moving around near the port, like the cabinet covering. It's an outside chance but worth a check. The Beyma will probably shift more air than the original driver so chuffing is certainly a possibility. You can't just add a port, that will completely change the tuning of the cab. You'd need to considerably modify the cab if you need a bigger port, possible but it might be easier to build a new cab, and cheaper if you sell on the Ashdown which will lose most of it's value if no longer original. Low B at full power is always going to be a challenge for a single 12" speaker but let me have the depth of the port and i'll have a think.

[quote name='Bill Fitzmaurice' timestamp='1496144686' post='3309067'] I don't know about Linden, but American Basswood is too lightweight for speaker cabinets. It's considered a junk wood, not suitable for construction or furniture. It doesn't even burn well. [/quote] It's just not something we see over here as a plywood so I've no experience of it. My son lives in Japan and when we visit I grab the chance to look at Japanese joinery. I don't recognise many of the timbers and like everything in Japan they try to use Japanese materials. The ply I've seen is fantastically good quality but was being used for finish work so you'd expect that. DIYJapan you need to just chat with your timber merchant about it's suitability, you don't get to do anything in Japan without a hell of a lot of training so they are likely to be knowledgeable about timber even if not speaker cabs.

[quote name='Thunderpaws' timestamp='1496179548' post='3309432'] Is it the volume of the port that matters? For example, if corner triangular prisms were used, should the volume of the prism be the same as the volume of the cylinder that makes a circular tube port? [/quote] Yeah, as Beer of the Bass says you need to calculate the ports for each cab and tuning but in a practical sense the length of the port depends upon it's cross sectional area so if the corner ports are the same area as the round ones their length will be the same. There's a slight complication because the termination of the port has a different impedance against the walls of the cab so there will be a small end correction to apply. In practice the cab would work OK but you probably wouldn't hit the tuning exactly.

[quote name='Count Bassy' timestamp='1496183854' post='3309468'] One thing (possibly the only thing) I remember from my Physics degree is that at the same pressure doubling the diameter of a pipe will increase the flow by a factor of 16, not the 4 times that the actual area might suggest. So, although 4 ports of diameter X will have have the same area as a single port of diameter 2X, the flow through the single large port would would 16 times that of a single port at X, or 4 times the flow of 4 ports of the same total area. [/quote] I have a distant memory of studying fluid dynamics 40 years ago and some 'interesting' maths. It should have been obvious but it's easy to get complacent when using computer models . I guess that narrow ports are more resistive and you get turbulence at lower port velocities.

Hi Geoff, I had a quick look at the Ashdown and I don't see why it wouldn't sound at least OK with the Beyma. It looks to be a similar sized cab to ours and I'm guessing tuned within the ranges we tried. If you could measure the depth of the port I could look at it properly for you. What exactly do you mean by "it isn't breathing smoothly at low frequencies"?

If you are doing covers I suspect it's about not knowing the song as much as being rhythm blind. There's a huge difference between being not being able to do something and never being able to do it. The difference is practice I don't think singing is as easy as it looks for most of us. I struggle to play bass and sing at the same time, especially when the chord changes don't line up with the sung line. Singers tend to be over confident, they can sing along with the original so they reckon they can do it to order. By now I'm imagining their confidence is shattered as it has been a topic of debate which probably doesn't help. With three weeks to go I'd be thinking of cancelling TBH, but you want practical suggestions. They have to listen to the songs over and over again at every available opportunity. Get another band member to cue them in either by counting them in or by playing a cue or even giving them a nod or a wink. Can they come in on time with a Karaoke track? If you can get backing tracks for your songs it gives them something solid to practice with. Sit down with them one to one and go through the problematic songs listening to the originals, pick out what the music does just before they come in . Get them to listen out for that cue and practice that entrance only. 3 weeks isn't much time, all any of you can do at this stage is to try your best (who booked in a gig before you were ready?) once it is over your singist needs to decide if they want to spend the hours working on each song to bring them up to scratch. If not it might be time to move on.

Whilst I don't know about basswood as a material for ply I would imagine it would be OK, a whole variety of plywoods are available here and often the only part of the plywood that is the named species are the face plies. One supplier over here offers a generic 'hardwood' ply which I prefer to birch ply anyway. Given the quality of Japan's carpentry and the use of a lot of indigenous semi-tropical timbers I wouldn't be surprised if it is very decent quality. We designed the cabs so you could build two out of an eight by four sheet so 18sq ft should be plenty.

surprised no-one has mentioned the biggest difference between the Gibson and the Epi's. Gibsons are really light basses. The Epi's are beasts. I have to say mine created quite a stir at every gig I took it to, just the look of it really, and I loved the sound it made, the sustain and the super fast narrow neck. In the end the neck dive and the twist spoiled it for me. I watched Martin Turner (Wishbone Ash https://www.youtube.com/watch?v=mUolWNHxRiM ) last Friday and like most of the T-bird players he plays mainly with a pick and the bass on his thigh with his picking arm resting against the bass. I play finger style only and without that restraining arm they dive like crazy. I sold the Gibson, it was a waste to have a lovely bass unplayed, then I missed it and a Japanese T-bird came up, a Burny by Fernandes. It has the same light weight and fast neck, the sound is great but without that snarl the Gibson has when you dig in. If the OP is thinking about a purchase try the Epi and Gibson next to each other, it's a completely different experience. Personally I'd wait and see what Epiphone bring out next if a new model is due soon.

[quote name='geoffbyrne' timestamp='1495907223' post='3307512'] Hope not to derail..... I have a Beyma 212 - but am totally hopeless with tools. Anyone building these cabs for money? G. [/quote] It isn't too difficult to build these if you get the panels cut to size for you. If you can use a screwdriver the Mk1 pretty much assembles itself. B&Q will usually cut the panels and a smaller timber merchant will usually help. Some might even offer to cut the holes in the baffle for you.

You'll find designing cabs is a bit like wrestling a balloon. You force one problem into place and something pops out somewhere else. We've very much found that to be the case with designing the Basschat 12. The main thing I was trying to achieve in the Mk1 was a decent speaker that would be easy to build. If you follow the original thread you'll see I built both a tube ported box and one with a wooden slot port. I plumped for the tube ports because of the simplicity of the build and the ready availability in Europe of black downpipe of the right diameter. We ended up with four to keep the port noises down. The slot port version had a resonance when I dropped it, I couldn't leave it alone though and when I went back found it was down to a reflection off the port itself. I damped it down with some judicious stuffing and it could have been designed out with a taller narrower cab. Having built both I thought the tube port tube design was easier to make for someone with limited tools and woodworking experience. Since then working on the Mk2 we've found that a single port gives a lot less port noise than a group of four with the same cross sectional area. I'm not keen on four corner ports for that reason, but it does help stiffen the cab. Balloon wrestling again. My conclusion? I wouldn't worry too much about the ports. If you are a confident woodworker forming them out of wooden slots is fine. The four ports in the Mk1 have never made any audible noises at a gig, even when pushed hard, most/many manufacturers of bass cabs make slot ported designs and there are successful designs out there with corner ports.