Phil Starr

Here you go.First of all notice that only the lowest frequencies are showing. The upper frequencies aren't affected much by the cab. The average output of the speaker is set to 0dB on tis graph. Anything louder is above the nought line and anything below is quieter. We use dB's because it is close to how we hear things. You can see that this speaker in this cab starts to roll off at just above 100Hz and is 10dB down at just below 50hz. You can also see that there is a 2dB peak just above 100Hz. That peak is going to warm up the bass but there won't be too much deep bass. The only way you learn that is by trying out cabs you know and listening out for what each sounds like but it helps to compare cabs. If you look up you can see in Balcro's charts how the same speaker behaves in a bigger 50litre cab. More bass and a flatter response, that's a useful bit of information.

Ha ha you aren't asking for much However I'm sat in a waiting room waiting for some test results so here goes. To completely simplify the whole thing if you know all the forces acting upon the cone and it's mass you can calculate how far it will move at each frequency. That's essentially what winISD does. Once you know that you can say how loud it will be at each frequency and print that off as a frequency graph. The first thing to look at IMO is the frequency graph then. I'll copy one down as an example and explain

Those graphs are interesting, and the differences are to be expected really. First of all the power handling: The cast chassis of the SM212 will conduct a little more heat away from the magnet than the pressed steel frame which explains the extra 30W of power handling. Although similar these aren't the same speaker with just the frame changed. The voice coil is different and the net effect is that the damping of the cheaper speaker is less. That's why in a 50litre cabinet there is a peak of about 2dB at 90-100Hz. I suspect that would sound quite nice for bass guitar but not so good for FRFR use. I prefer to roll off deep bass in most of the spaces I play so I don't think you'd really miss the slightly earlier roll off. In fact though you might notice it if you had both speakers there I think it would be subtle enough you probably wouldn't notice, the 2dB peak would be the thing that would dominate bass response. I'd imagine the 12 CMV2 would be less good in the 30l cabinet than the SM212 but I haven't modelled it yet.

Welcome to Basschat. I'm pleased someone resurrected this thread. Quite enjoyed the spat and then Neil Murray wading in, what a bonus. Particularly enjoyed his comment about not being able to do all the fills if it was played too fast. FWIW I struggled with this. In the end nailing the chord changes and not worrying about the fills unlocked the song for me. Once that was done you can add in your own fills as it all moves into muscle memory and you can start to relax. It was forced on me by a guitarist who never did nail the solo but I'm grateful as it made me improve the approach I take to learning new songs.

It may be this one though there are a couple of discrepencies with what Blue Aran are showing http://www.beyma.com/getpdf.php?pid=12CMV2

If anybody wants it and is prepared to pay postage or pick it up I'm happy to give away my prototype cab. It isn't my finest work, as a prototype it's been modified a few times, and it's an empty box, the speaker has been returned to my PA cab and I've scavenged some of the fittings but if someone wants a Mk1 1x12 then its a working cab free to a good home.

More probably they have decent power supplies and are being used within their limits and with terrific drive units in the speakers. My point is however that there is nothing wrong with class D it's about implementation and I wouldn't want you putting people off seeing if they suit their needs. It's the science teacher in me, or the pedant. I can't bear it when someone says something which isn't supported by evidence. If you've tried all the class D offerings form Ashdown, Markbass, Fender and so on and found them wanting then that's fine but in reality I don't think you could reliably distinguish between a switch mode and class A/B amp. You can surely see you kind of contradicted yourself in your own answer

You probably get fed up with people saying this and it isn't meant personally. I've always said if you listen to a rig and love the sound then it's right whatever people say on Basschat. I've also listened to some of the vids you've put up over the years and it sounds good to me, and you are right about your own rig but there's a but coming.... BUT, the decent FOH and decent monitors are probably class D.

If there is a 4ohm speaker in there then that's it, you can't add anything. Putting an 8ohm speaker in there will lose a lot of the tone but allow you to add a second speaker. Some of these old combo's had switched extension speaker sockets, plugging an extension speaker in disconnects the internal speaker. The min 4 ohm warning would make sense if that is how this combo was designed. You sometimes see combo's where you can physically pull out the jack for the internal speaker and plug another speaker in. If you did go for an external cab one socket isn't a problem, most cabs have two sockets so you can just 'daisy chain' from the second socket to the second cab.

I love the sound of week old Rotosounds, just a bit too bright when brand new but they hit that sweet spot once they've been played a few times, but it is way too expensive for me to keep replacing expensive strings. I've gone down the other route, looking for something that has an acceptable (to me) tone after a few months. Two strings have done this for me, Elixirs which everyone knows about and Dean Markley Blue Steels. I ran my own test a few years back leaving them on basses for two years. Both made an acceptable sound even after all that time, the Elixirs lasting slightly better, but not by much. Both basses came back to full life when I re-strung though. FWIW I restrung both with Blue Steels and I'll probably stick that way, though £4.40 a set looks tempting. I've boiled and cleaned strings in the past and found it not really worth the bother, it makes a difference but only for a short while. I'm not convinced Fast Fret and the like works to prolong life either, any oil is going to turn to gum over time and make the string a dirt magnet, sure you'll clean the surface but deep down in the grooves? I guess you'll have to decide a yearly budget for strings, £100 a year would buy 22sets of the Harley Bentons, 3sets of Blue Steels, 2sets of Elixirs or 6 sets of Rotosounds. I like a slightly less bright sound and a couple of sets of Blue Steels a year does me. I'd struggle with the waste of 20 sets of strings a year.

Good that makes it simpler really.

Falcon Acoustics are really good for this sort of thing and are quite likely to have data for most KEF speakers. Capacitors are really quite simple to find and they wind their own inductors. Having said that Stevie really knows his crossovers to the extent that I'd ask him first every time for advice.

Then you are putting them into two cabs that will be spot on. My cabs are slightly over 30litres to allow for the volume of the speakers and the ports. Are these from one of the dual impedance Epifani cabs? Crack on and tell us what they sound like

Honestly I couldn't tell you how much difference that would make, polystyrene foam is air trapped in a plastic matrix much more air than plastic as you'll discover if you burn it (don't, the fumes are poisonous) It's a closed cell foam and relatively rigid but it will still transmit sound. More to the point is that you may not have a problem. have you measured the original cab yet?

The main issue for me would be what I was told at the start. I'd always make clear to someone what they were getting into. If I wanted them to just join, play the set and just be a hired hand then that is fine as long as you say so up front. Generally I prefer a democracy (so long as I am first minister of course) and certainly money is split evenly when I'm band leader. As a bassist if somebody said up front 20 gigs a year, £50 a gig, learn the songs I'd be perfectly happy. No responsibility, just gigs, why not? Are you perfectly happy? Apart from not being put in the picture which would annoy me too. Decide whether you get enough back to keep playing with them. Nice people, regular quality gigs, that's a couple of decent ticks. It wouldn't be unreasonable to ask where you stand either, just a polite request for clarification. The other issue is whether you are missing out on other gigs as a result of your commitment to them. Most bands are driven by one or two people who are close IME, the only alternative is to start your own band. If they are doing all the work though I don't see a problem other than they should have made things clear up front.

I like Andertons and am glad to say so. You ring up and get a real person, however slick some of the mail order people are you can't help but prefer the ability to actually talk to somebody who wants to be helpful.

Is that an old Peavey? Yeah if you measure the internal volume of the cab then divide by the number of speakers that should give you the volume you are aiming at. If the original designers knew their stuff. If it's an old 4x10 you can even afford to blow a speaker, and cut up the grille for your new cabs Remember this was a deliberately undersized (for the Beymas) cab to trim the bass response for difficult rooms, it may well be a decent match for your 10's and the 50Hz tuning may be OK too.

I remember turning up my Dad's amp (when they were out) and listening to it with a pillow over my ears to filter out everything but the bass. It took me 40 years to get round to picking up the bass but I always knew it was for me.

It depends upon the speakers entirely. I'm not sure if you are building the big 50l box or the smaller 30l one which is more likely to suit a random 10" speaker. Are they bass speakers or just some generic 10's? The thing is that they will work, in that they will make a noise, you may even quite like the noise. Without getting too technical if the cab is too big to match the speaker you have you might get some nice deep bass but with a gradual roll off and reduced power handling, it's not uncommon to see power handling reduced to 25% of the rating at certain frequencies. If it is too small then you may not get a lot of deep bass but a boom boom upper bass with not a lot of definition. If you just want to have some fun then if you just play at home levels then power handling should be fine and you'll be able to play. I probably wouldn't want to gig with them in a rock band without knowing more about the speakers. Where in between those extremes they'll operate, well that's a gamble. To be fair if it is a bass speaker or a PA speaker they tend to have broadly similar enough characteristics that a moderately sized cab tuned to 50Hz will kinda work, with the reservations on power handling. A rolled up sweater wouldn't work anyway, you'd need something solid like a brick.

Looking good, don't worry if everything is air tight they should work perfectly. I hope you like the way they sound.

Surprised that no-one has spelt it out yet though it's implied. The gig comes first, if you accept a gig then you have to honour it even if the other band comes up with a better gig later on. Once a band accept the gig they are letting all their band mates down if they try to become a no show. Not to mention the band will soon get a reputation too so doubly bad. first gig in the calendar is the one you have to do.

As a system it will do what you want but it might be worth some time auditioning some speakers and deciding what you want. Your folded horn speaker is going to have a very strong characteristic sound all it's own. Losing that might be something you'd miss or an albatross off your back of course. If you like the Mark Bass and you need more volume get another then you know it'll make a sound you like. you could even consider going for an active PA speaker. Basically a PA amp and speaker closely matched in a single box for slightly less than both bought separately. Basically though go for something that sounds the way you want. Looks like you tend to keep stuff so you might as well start with something you like as it'll be there for some time

Essentially you just need to know the cross sectional area.Add the ports together and then calculate the length. pretty much all the programs let you calculate assuming a circular port so you can just work out what diameter port would have the same area as your four triangular ports. WinISD lets you use rectangular ports which makes it even easier. Yes in theory you ought to allow for a different end correction but the change is tuning will be small. the manufacturers figures for speaker specs are rarely spot on so that's all academic. In practice you'll usually find what you have is close enough. I tend to build, check after and then if the tuning is too far out adjust the cab If it is too far out. It rarely is in practice often you are talking less than a cm of port length and a few Hz in tuning

any progress on this?

you rally shouldn't have a problem. Amps and speakers are rated by completely differet techniques so their power ratings bear little relationship. Amps are really simple beasts. They amplify the voltage until they reach the voltage of the power supply and this is their upper limit and the rating of the amp is worked out from there. That's the loudest sound an amp can make Speakers break in two ways, put too much power in and they will overheat and eventually fry. Alternatively put too much bass through them and they will over extend the cone moving the voice coil out of the magnetic field and maybe even banging it against the back of the magnet. Their testing is simple enough, pass a signal through the speaker increasing the power and eventually it burns out. just below that is it's power rating. When you play music however you don't pass a continuously high signal through the speaker. You play a note and it decays before you play the next, sometimes you play the notequietly sometimes louder and sometimes there are breaks. All this means that your average power to the speaker is way less than you think. Your loudest sound might need 100W to be clean but the average power for your speakers will be only 2W, they won't over heat. The main threat is bass over extension. The other way o looking at it is the sound levels. You say you play at modest levels. Well even in a rock band going flat out you won't need to be louder than the drums. You'll usually get something like 99dB/W out of a couple of 12's so 150W will be loud enough to do almost anything other than massive bass boost or drown out the est of the band. In reality your quietish on stage sound means you won't be running at 800W ever. There's no protection against idiots thrashing their gear with no respect for everyone else on stage or their gear but I don't think you need to worry, just be aware. I'll use the car analogy. Your car may rev up to 5000 revs but if you thrash it round Brands Hatch never letting the revs drop below 3000 then it won't last long, drive it normally and you'll probably never get anywhere near 5000 revs and never need to worry about the limits.