Phil Starr

Your English is fantastic, the only evidence of it being a second language, never mind a third is that you are slightly more polite than we are with each other Please don't worry about sharing ideas either, it is good to share and I certainly don't have all the answers. Any suggestions you make are welcome. Thanks for clearing up how you generated your data. It is something I had wanted to do and it would be good to try a range of basses. It would be nice to see what the difference between a P and J bass actually was for instance. It is always good to have an input from people who are actually manufacturing speakers. I wish you every success. For those who haven't noticed TKS are already on their own thread and you can see some of their speakers here [url="https://www.facebook.com/pages/tks-Engineering/154937774584383"]https://www.facebook...154937774584383[/url] .

Tks talks about a cheap 10" speaker, though it isn't clear if all the tests took place with the same speaker. The implications for our design and any other designer are that we can take a few more liberties, which we kind of knew. I like to explore the extremes though so we can predict behaviour. I hope that what people are getting from this is that though the maths gives you the predictions there is lots of room for setting the compromises in different places. For those who don't know 6V6 built an earlier design based on the SM212 which is very similar to our design so his comments on his speaker are absolutely based on experience and relevant to our design

I'd take the measurements as indicative only. All basses have a different timbre, or mix of harmonics. The pickup positioning is going to be critical. The further up the string the more fundamental and the less harmonics you'll pick up. Put it on the 12th fret and you'll get maximum pickup of the fundamental and the second harmonic will be absent as the node will be above the pup. The Pickup itself will have its own frequency response and where you pick the string will also affect the way it vibrates. However even if this is one bass, through one amp and speaker it ties in with what you'd pretty much expect. I hope we do get some more information, my Swedish is non-existent so I'll have to wait. Could you do your own measurements Stevie?

Really sorry guys, it would have been good to get a few opinions. I've been gigging a lot recently so this is the first weekend free for a long time and I'm going to spend it with someone I love

[quote name='tks.se' timestamp='1412160565' post='2566219'] When playing a low B, most of the tone consists of harmonics to the fundamental. Here's the result of playing a low B and running the signal through a spectrum analyser: If we "translate" those dB (logarithmic) values to watts (voltage swing would be better, but using watts makes it a bit more intuitive for most) and use say 200W as a total, you get the following "wattage distribution": Different basses, fingers, plucking style etc give different responses/harmonic distribution, and this also changes over time (the harmonic distribution of a ringing note differs from that of the attack). The main thing to focus on is that a low B is never a 31 Hz only tone, most of the "energy" is distributed in the harmonics. Because of that a 50 Hz tuning doesn't mean a death sentence for a SM212 (nice speaker by the way!) even when playing a low B at full power. Great initiative with the design diary! [/quote] Thanks That's great information, do you have a link? I suppose I'm designing for worst case, because someone somewhere is going to think they have a 350W speaker that can reproduce anything they throw at it, add 12dB of bass boost from a traditional tone control and the wattage distribution would look very different and my suspicion is that someone, somewhere will do this. I suppose the possibility of designing this hazard out was worth a look, in the end the compromises weren't worth the gains and I'd advise anyone with a fiver who wants to drive at extreme sound levels uses at least two speakers and preferably a filter like a Thumpinator.

Final one this morning. For some reason the winISD plot won't go up. If I halve the port area of the 40Hz tuning I can use a shorter port, it now fits inside the speaker!! The plot you can't see now shows the air velocity inside the port. The faster the air moves the noisier the port gets and you'll hear chuffing noises at somewhere between 15 and 17m/s. Now we have the port down to reasonable dimensions but with the same air moving through it the 40Hz tuning will start to make noises. So we have to compromise; tune to 40Hz and accept a noisy port at high volumes or 50Hz and have to de-rate the power handling for 5stringers or users of octavers. The solution for us is to go for 50Hz tuning. I'm the one who hung out for the lower tuning but the other guys are right really. Why the hell would you think a single 12 is the way to go if you want a stack to handle full power fundamental from a 5string?

file:///C:\DOCUME~1\dad\LOCALS~1\Temp\msohtmlclip1\01\clip_image002.jpg[size=4][attachment=172886:clip_image002.jpg][/size] [size=4]OK if I've got this right this should show the frequency response of the two cabs. Pink is 50 Hz and Yellow 40Hz. You'll see that 40 is flatter and tails off more gradually and a 50Hz tuning gives a bit of extra bass between 200 and 50Hz. whether you see this as extra warmth or distortion is a bit of a matter of taste, and at only 1dB I doubt you'd notice it unless you are listening for a difference. The point is that mucking about with tuning affects the low frequency response, and it might be greater for other speakers and other cabs. Without the simulation you won't know.[/size]

[size=4][attachment=172884:clip_image002.jpg][/size] [size=4]OK update on the design process, which is back to where this thread was originally meant to be, I feel sorry for anyone who comes to this in the future to try to find information [/size] [size=4]The biggest problem we are having is to select the port dimensions. Tuning the cab is easy as winISD will calculate all this for you once you have decided what outcome you want. the problem is deciding the outcome. It is always a compromise and all the cabs you might buy have had the compromises decided for you, however high end they are.[/size] If the plot above comes out then it should show the cone excursion at 300W. The pink curve shows the cab tuned to 50Hz resonance and the yellow to 40Hz. the red horizontal line shows Xmax, the point at which the speaker coil leaves the magnet and the speaker starts to distort. You'll see that they both start to distort at 100Hz and the 40Hz tuning distorts more. Because Beyma use the worse case calculation for Xmax it is unlikely you would notice any distortion at all with the pink 50Hz tuning and in practice, probably none at the 40Hz tuning. So far, so good. The problems come below the port tuning. Look at the 30Hz line and you'll see the excursion shoots up to 11mm and 18mm. Critically at 13.5mm for this speaker the coil hits the back of the magnet, and this will destroy the speaker. Low B is 31Hz. This means the speaker won't handle 300W of low B fundamental if we tune it to 50Hz. So we tune it to 40Hz right? Well no, not necessarily, because this causes other problems. One you might be able to see on the image. The port length is bigger that the cabinet for a 40Hz tuning. More about this in my next post.

The prototype is 53x42x36cm (exterior dimensions) I don't think that will vary by more than a cm in any dimension in the final version. My rack mounted Hartke sits nicely on the largest face. Because it is a self build you can vary the shape to get the exact dimensions you want so long as the internal volume stays the same. I'm going to offer everything down to a cutting list to people who just want to make a perfect copy but the reason we are giving all the design details away is so you can tweak the design if you want.

There are two variables here, the cab and the venue. The acoustics in some venues are appalling. Low frequencies are hard enough to hear clearly at the best of times but if you are shoved into a highly reverberant space with a not very lively speaker which is pointed at your legs not your ears then you won't hear anything, even though it may be fine for the audience.

Sorry, can't do the 12th, family commitments.

There are two technical issues with using PA cabs, actually the same issues are shared with all bass cabs. Neither of them should be an issue with a properly designed PA cab. Bass needs lots of air to be shifted if it is to be loud, this means lots of cone area and/or the cone(s) need to move a long way. Cheap speakers with cheap magnets can't do this generally. PA cabs should be able to put out exactly the right amount of bass to match the output of the rest of the band so should be able to cope with bass at that sound level with no problems, otherwise what's the point? However cheap PA's compromise this and are often only used as vocal PA avoiding this issue. The other technical is distortion, if you play with lots of distortion/overdrive then it generates lots of extra high frequency energy and you will burn out the horn drivers. Not a problem if you play clean. If you bought a new PA speaker and it had DSP built in then none of this is a worry the DSP makes your speaker idiot proof and turns it down if you do something stupid. The other non- technical issue is that of taste, bass cabs are rarely uncoloured because the colour is the 'sound' of the cab. PA cans should be uncoloured so will sound different. If you like DI'd sound then you'll like using PA cabs. Another issue is cab resonance, bass cabs generally are fairly massively built to resist low frequency resonances. PA cabs are generally made to be light enough to be thrown on top of poles and are engineered to suppress resonances across the frequency spectrum. I'd avoid one of the polypropylene PA cabs as a bass monitor but most reasonable quality PA cabs will handle bass as well as most bass cabs. In some ways the bass unit in a PA cab can be more specialised for bass than a bass speaker, as the horn does all the top end. Try your cabs at home, turn the power up gradually to slightly louder than you would normally play and run up and down the lowest octave on your bass listening for any strange noises from your cabs, stop if it happens. If it doesn't you are good to go. Don't do this at a gig because the signs your speakers are being damaged will be masked by the rest of the band.

I'm struggling to do the same thing, not helped by a poor pitch control so i need to concentrate on the singing and controlling my breathing. Three tips: Practice the singing along with a recording without the bass, you have muscle memory there too as I found out when I practised in a different key to the band. If it's in memory you can spare a bit of attention to the bass too. Really mark the bit of the bass line the first word of the lyric sits over and make sure your bass and the vocal are locked in at that point, practice both with a drum machine if you can. Simplify the bass line and follow the vocal line with the rhythm, may not be ideal but far better than the bass losing timing altogether. I'll be watching for tips here myself.

Might be better to look into re-coning it, which means it is still the original speaker.

Yep the magnet material makes no significant difference as far as performance is concerned. All other things being equal the more powerful the magnet the smaller the cab needs to be and the louder the speaker will be. Powerful magnets cost, neo doubly so. Powerful ceramic magnets are very heavy though so its a trade off between the weight saving of the cab versus a heavier magnet or high cost neo. The trouble is there is another fashion for flatter more extended bass response running alongside the move to lightweight. To get this you trade efficiency so you need bigger more powerful amps for the same sound level. So, modern means neo and modern means more[size=3] amp [/size][size=4]power, but for two different reasons.[/size]

The aging of speakers is relatively complex and a range of components will change over time. Any polymers used in the construction will continue to cross bond, that is there will be new chemical bonds formed between the long chain molecules that make up the plastic and rubber parts of the speaker, mainly at the cone surround. This is why plastics become brittle with age. The old foam surrounds used to be particularly prone to this and broke down after only a few years. The edges of the cones or even the whole cone may be treated with a damping material and of course the glues which hold the speaker together are also polymers subject to this process. The wood pulp used in the cone will also age, cross-bonding between the fibres made essentially of lignin will increase but this will be overtaken by the physical breaking up of the fibres which will soften the cone over time. Actually speaker cones are not rigid pistons but are designed to flex at higher frequencies and in most bass speakers the surrounds are in any case formed from the same material as the cone itself. Most old speakers initially break down at the first roll in the surround. The fibres are mildly hygroscopic and absorb water from the atmosphere eventually swelling slightly. Then in high temperatures and dry conditions they will lose that water so go through a process of swelling and shrinking which further softens the material, the degree depends upon where you are in the world. The cone will also accumulate dust and will get heavier, lowering the resonance. You'd also expect some colonisation by fungi especially in damp conditions. Speaker coils also go through dramatic heat changes, reaching several hundred degrees during high power use this can end up distorting the coils and leading to failure of the speaker but will also heat the magnet. Depending upon the magnet material this can end up losing some power over time. Modern magnet materials and coil formers are designed to mitigate this and are pretty impressive though some 50's and 60's speakers may have lost a lot of power and drifted off spec. You wouldn't expect any mechanical component moving thousands of times a second to last forever without wear. There will be changes in sound but they aren't usually dramatic and there are many bass players out there using vintage gear quite happily.

Not sure about family commitments that weekend but if I'm free I could bring the Basschat 12" cabs along http://basschat.co.uk/topic/227904-1x12-cab-design-diary/ and do a talk about designing bass cabs.

[quote name='GrahamT' timestamp='1411291091' post='2558101'] As my job is near Taunton and I live in Hemyock, any of the above areas would work for me. I am always keen to try out new gear. Jimrs2k has built some Fearful cabs which are awesomely powerful. He lives at Ashcott, on the Bridgwater to Street road so he may be a useful local contact for you. [/quote] It would be ideal to compare the new cabs with other offerings, commercial or home builds and to try out a range of amps and basses with them. Could be fun.

[quote name='yorks5stringer' timestamp='1411148461' post='2557020'] If you'd venture into Dorset/Somerset there's always the Queens Head at Milborne Port, venue from the last Dorset Bash....? Sorry, don't want to hijack the SW Bash but it seems to have gone quiet...? [/quote] Yep that's a distinct possibility and there are a group of you who would be happy to meet there I guess.

Wait a bit and keep calm. I started playing when I was 55 and you have to ask the question how many people would have you? Secondly it always sounds awful because when you first play in a band you think it is going to sound like all the recordings you ever listened to the reality is without a proper mix and with all the problems of hearing each other it usually sounds much worse for the band than it would for the audience out front. Now playing with my fifth band I've adjusted to rehearsals and working with new bands. It takes time to sound good but after a few practices it should start to come together, if you are all experienced that happens quickly but if you have two people who are veryrusty/inexperienced you need to let it ride for a while and keep your expectations low at first. In a couple of months you'll know if you are all improving and then you can make a decision if it is for you or not, unless you have another band waiting for you already you have nothing to lose and loads to learn so stick with it for a while and see if it goes anywhere. As to not being able to learn your part because they move the goalposts, welcome to the world of musicians. At this level you are unlikely to have anyone with a sound grasp of musical theory or any language to describe what they hear in their heads. So many people talk about putting their own stamp on music but take that with a pinch of salt. As a bassist you can always get away with playing the root note in time with the drummer especially if you hit the first beat of every chord change. Once you have a half dozen practices you'll find very little changes and you can add to a basic bass line from then on. Don't expect too much at first other than to get better at each rehearsal, don't criticise band members who are probably low in self confidence anyway and enjoy yourself, it will get better.

[quote name='skidder652003' timestamp='1411145074' post='2556954'] Hey Phil if its 4 ohm, I'll try and destroy it through the SVT ! [/quote] Given your history Steve!!! You'd be welcome to try them out, with or without a meeting.

Hi Guys, I need some help. I've been designing a bass cab for Basschat and have a couple of prototypes. I think they are great but then I would wouldn't I? I need some fellow bassists to come along and give them a try and make some comments so I can tweak the design. I'm happy to just organise a venue and meet up and do this informally, or if enough people want to give a little talk on speaker design or to incorporate this into a proper bass bash. All I need is some bassists to try the cabs, I'll organise the rest. Is anyone interested? I'd look for somewhere Taunton/Axminster/Honiton area probably, though I'm open to other suggestions if someone else can find a pub that will have us.

+/- 4mm, that must explain the fit on American cars! (joke Bill ). Seriously most timber merchants in the UK are going to cut within +/- 0.5mm and my experience is better than that. Explain what you are doing and they'll take a little extra care usually. If they mess up then take it back and ask them to do it again. If they can't cut the panels for a simple rectangular box more accurately than you can with a circular saw and a sled then there is a real problem. This is a red herring frankly. Although I have all the gear in my workshop I often get the stuff cut at B&Q or wherever simply because it makes it easier to transport than 8x4 sheets. One tip is to prepare a cutting list and to mark up the cuts themselves on a drawing. I draw out an 8x4 on graph paper and mark out the panels to scale. Otherwise the usually untrained assistant starts cutting before they start thinking and you end up with a lot of waste material. Don't forget to allow for 5mm for the saw cuts if you do this.

You have 14 days I think to return to Andertons, they are good to deal with as I found out this week but you don't have much time. I've re-read your posts and I think mic technique is probably a big issue. you don't say which Sennheiser she used but using a stage mic is difficult for most people, they are mainly designed for very loud environments and to reject feedback, To do this you have to eat the mic. The SM58 is a cardioid which demands less mic technique than a supercardiod. you'd expect Sennheisers to be louder than the SM58's which indicates mic technique is an issue. A headset mic might be a good idea as once it is on you can forget about mic technique. Thinking about your needs I reckon you should think in terms of losing the guitar amp and having a single amp that does both guitar and vocals. there are three ways to go. An acoustic amp with a mic input, I've not used the Marshall but the better amps of this type have a very flat response and are no more prone to feedback than any other system, if cost isn't an issue the AER's are very good http://www.thomann.de/gb/aer_compact_60.htm?sid=f82773e9361901d92390e81571fa31e0 , there are much cheaper versions but I haven' tried them. A PA package like the Yamaha Stagepas 300, is a terrific setup for what you need, I have one of these and they are great, Two very light speakers with a 4 channel mixer and featherweight 175W amp built in. No trouble carrying in the whole PA in one journey.They were the first in the new wave of PA systems designed for exactly the sort of need you have and they were soon copied by a whole load of me-too designs which may well be as good, but I haven't tried them. http://www.soundonsound.com/sos/mar06/articles/live_stagepas.htm PA speaker route, if you just want vocals I'd strongly recommend the Wharfedales, Since my post I've used them at two gigs as vocal monitors given them a thorough going over at home and used them for PA at a couple of rehearsals, the sound is fantastic so long as there is no bass content. However if you wanted to cut down the gear you carry and rationalise your system then they only have one input so you'd need a mixer to use the guitar as well. There are plenty of PA speakers that have two inputs so they would probably be a better bet http://www.thomann.de/gb/jbl_eon_515_xt.htm However I think mic technique is the real problem and a worn mic might be the solution. The other is to practice at home, it takes a while to get used to hearing your voice amplified and if you are naturally shy it takes a while to get used to it. Did you have a budget in mind?

On a technical level there is no reason a 10 can't move as much air as a 12 as this depends upon how long the cone movement is as well as the area, they count equally. A 2x8 has a cone area roughly between that of a 10 and a 12. I'm not sure it helps but you can't decide this on cone area. The power probably matters only if you start thinking of extension cabs. 100W is probably enough to drive most of these speakers into distortion at the lowest frequencies so you'll probably have to judiciously cut a little bass if you turn the amps right up. I'd say if you intend gigging these little things then a DI out is important as you can then easily use a bit of PA support. a worthwhile extra. Fundamentally though you should base your decision on the one you like the sound of best.