Phil Starr

[quote name='Beer of the Bass' timestamp='1447534959' post='2908455'] Is there an issue fitting in enough port area with that volume? I've noticed when playing around with WinISD that it can be a bit of a juggling act with smaller cabinets. [/quote] Yes, though at a practical level the potential length of the ports is at least as tricky the port can end up longer than the cab! i ended up with quite small ports which potentially give you a bit of port noise at low frequencies. It's all about which compromises you choose to make The proof of the cab is in the hearing

You need to completely bypass the tweeter. The easiest and reversible way to do this is as follows. Open up the cab probably by removing the 12" speaker. Locate the tweeter, main driver, speaker socket, and crossover. you should have a set of two wires going from the socket to the crossover and then one set going to the tweeter from the crossover and one set going from the crossover to the main driver. If not then don't panic but ask again. If you can solder then I'd desolder the main speaker connection at the speaker and the lead to the crossover at the socket. Then I'd connect the speaker directly to the socket with new wires. That way you can simply resolder the cab back to original and remove your new wires if you want to sell your cab. If you can't solder and don't mind bodging in a less than ideal way then what you can do is cut the lead/wires from the socket to the crossover a few centimetres from the crossover and the leads to the main speaker also close to the crossover. Now if you are lucky they will be colour coded the same way. Connect the cut leads together so that like goes to like. It is essential that the connection is completely secure and that the exposed joins can't touch and short circuit or you could blow your amp. It's messy but you could use connector block (chocolate box) or some crimp connectors as used in car electrics (I can feel Bill shuddering at this point). Don't trim the wires in case you want to reconnect them. If you get the wires the wrong way round the speaker will work but if you use it with a second correctly wired speaker you will lose all your bass. If this happens reverse the connections to the main speaker. Try the speaker at VERY LOW VOLUME whilst it is still out of the cab, it will sound tinny but you at least will know it is working. Finally tidy up all the loose wires inside or they will rattle once you start playing and put the cab back together. Alternatively take it to a tech who will do the job in 20 mins and only charge a few quid. It's not a difficult job but it has to be at your own risk. Do you feel lucky

Funnily enough you've caught me messing around on WinISD with smaller cabs. A 35l cab looks interesting, roughly 1dB up from 100-200Hz but 3dB down at 40-70Hz. I think if I really wanted to go for a lightweight cab then reducing the size and compromising on deep bass looks interesting, you'd lose about 3kg and the panels would be inherently more rigid. I find that size affects portability just as much as weight.

[quote name='stevie' timestamp='1447511926' post='2908204'] On the matter of cutting the holes for the port tubes, I bought an adjustable hole cutter recently for less than a fiver which may not be the last word in pro tools, but will do the job perfectly well. It might take a few tries on some scrap pieces of wood to get the size spot-on, but it's not too difficult to do. [url="http://www.ebay.co.uk/itm/Handy-Adjustable-Metal-Hole-Saw-Round-Circle-Cutter-DIY-Tools-Accessory-/252069704389"]http://www.ebay.co.u...y-/252069704389[/url] [/quote] I use one of these http://www.toolstation.com/shop/p45494?table=no either look good for the job. Building the slot port design was slightly trickier than building the tube ported design so I'd agree with the decision to go that way. I'll offer notes on how to build the slot ported design as others may prefer to build that. It does look very nice IMO but I'd rather go the trouble free route.

Don't buy a bass amp. Clean is a subjective term, what you are asking for is flat. The sound of the bass DI'd into the PA, though when you hear your bass through a ruler flat system you may decide you did want subjectively 'clean'. Your best bet for the DI'd sound is a PA amp and speaker. For that budget you could buy something like a single RCF or similar. Maybe a good quality floor monitor. I'm guessing that you have monitored through good quality headphones? If not I'd try it just to check that this really is the sound you want. Don't go for a cheap quality PA though, the bass drivers often won't handle high levels of bass due to limited excursion on the bass driver.

[quote name='LukeFRC' timestamp='1447357499' post='2907082'] forgive me for daftness - and maybe it's something simple - but maybe the ports and 15mm are a better method of construction? (and lighter) [/quote] Not daft at all and I'm trying to modify the design by absorbing people's comments so they are all welcome I've given details of both so people can make a choice if they want to construct one of these. I'll include notes of both in the final write up too. Personally I prefer the 18mm construction with the tube ports, but I have a proper hole saw to cut the ports. Both cabs are an easy carry anyway.

[quote name='Thunderpaws' timestamp='1447353666' post='2907030'] What type of woodwork joint did you use for the slot port at the sides and with the bracing? Could it be vibrating at certain frequencies? [/quote] I think it's probably a standing wave problem as explained above. The joints are all reinforced butt joints, chosen to be easy to replicate for a home builder with limited tools.

[quote name='tauzero' timestamp='1447363858' post='2907161'] Taking a simplistic approach, the wavelength at 750Hz (which is where it looks like the resonance peak is) is about 46cm, so are there any bits of the cab that measure 46cm apart, or possibly 23cm? [/quote] Not simplistic at all. The baffle is about 45x40cm with the shelf of the port at the end of the baffle, so that is the simplest explanation and that critical point had no damping material at the time of the test so that will be my first port of call. I think we have set up some extra standing wave resonances in the changes we made to this cab. It's a problem with small cabs with biggish drivers that you end up with all the dimensions determined primarily by the need to get everything in and not by acoustic considerations. I'm also gong to put in some simple cross bracing into the 18mm cab. I had particularly wanted to compare an unbraced 18mm cab with a fairly heavily braced 12mm cab. Interestingly the 12mm cab vibrates far more than the 18mm cab and you can both hear it and feel it with your fingers. A single test on similar but not identical cabs proves nothing of course but I've always argued that mass is an important factor in panel resonance. What I've found so far bears this out.

Yes, the 18mm slotted which is the green one on the graph. Stevie's initial thought was that it was the driver, since the volume of the box and the tuning were the same. It now looks like it is something about the box which is creating the resonance. Frustrating but I'm glad we found it before publishing the design. We are investigating..... I'm hoping it is something simple.

[quote name='stevie' timestamp='1446054831' post='2896570'] I would have posted this a lot earlier but I hit a snag. When I started measuring one of the cabs I have here, it didn’t measure the same as the one I had had here a few weeks ago. I spent hours trying to figure out what was going on. I even started recalibrating all my measuring gear. Eventually, I pulled out a speaker that I know measures flat and tried it: it was flat. The penny dropped and I put the second cab on the bench and measured it. There was a problem with one of the Beymas. This makes a bit of a mockery of our comparison test at the Bash. This is how they measured. I’d say one of those was definitely not to spec. The red one is the good one, by the way. More to follow shortly. [/quote] Quick update, we swapped the speakers last night and the plots stayed the same so the big 700Hz ish resonance is a cabinet problem, not a problem with the drivers. A bit more investigation needed but it was partially tamed by a bit more wadding in the cab. There's also a big peak in the output from the slot port though it doesn't coincide with the resonance we were investigating. A little more work on damping materials needed before I release the final design. I'm also going to order up a couple of better quality grilles to give a better impression of the finish you might achieve.

[quote name='Phil Adams' timestamp='1447260179' post='2906224'] Helium filled balloons tied to the headstock will cure it as well, look nice, and if enough are used can give the player an aerial view of the audience. [/quote]Is this why your location is halfway up the stairs?

[quote name='Lw.' timestamp='1447239627' post='2905959'] I can't believe just how many people play with only one hand; are you not limiting yourself a bit by just playing E,A,D & G? [/quote] Not a problem with my band [quote name='Norris' timestamp='1447239361' post='2905958'] I had to read it a couple of times, but I think the OP has clipped his strap to the top of the bass as it rises from the bridge strap button, near the elbow of your plucking hand. I can see how that might prevent "top tilt" but not necessarily neck dive [/quote] That's it, and yes I did it to stop the tilt but it seems to have sorted the dive too. The bass sits against my body a bit better I suppose. [quote name='pfretrock' timestamp='1447236439' post='2905929'] I found the best cure for a Tbird neck dive is a P bass. You can thank me later [/quote] That's the solution I came up with. A lovely American Deluxe. I only gigged my Gibson for one gig. The sound was monstrous and it turns you into a real poser as you haul it back upright but after about an hour I found I was getting really sore lower arm muscles from adjusting for the twist, halfway through the second gig I had to abandon it and sold it shortly after but I missed playing it and went for a Japanese copy. Now I have the delicious problem of choice for gigs and a pang for the one that got away. It sounded so good.....

Hoping to go into the annals of fame with this one. All sorts of solutions from thick straps to hanging weights onto the bass but none work without problems. Playing the other day, wishing I could get the sound without the dive, when I looked down and thought 'if only I had a third point to attach the strap to the body of the bass' (where the lower part of the strap emerges from behind the body). I looked across at my skinny string and the light bulb went off. I removed the capo, clipped the strap to the Tbirds beautiful but flawed body and hey presto! The out of body experience of a Tbird I didn't have to struggle with. No more twisting in my hands and no neck dive at all. with the business end of the capo being the only bit showing it didn't look too bad either. I'm sure I can work out a better clip but the T'bird is going to get a lot more use now. you can thank me later

Don't accept compromise, but play fair. Insist on trying cabs, and buy from a shop which lets you try. You've found your amp and you want a matching cab which narrows down your search. Buy the amp and take it with you when you try, then it doesn't matter if the shop doesn't stock Orange. The only way to get a sound you like is to try because one persons perception of clean or filthy won't be the same as yours. If we all buy on the web then the shops will disappear. Many shops will match internet prices anyway within a few quid and you should get decent after sales so it's good financially in most cases. If you know the after sales is poor then the shop deserves to fail but that is another issue. (rant over) There's loads of good shops that carry a range of cabs, how about a trip to Brighton to try Barefaced. There are bass shows around and of course the bass bashes which give you the chance to try and to listen. Personally I'd rather take months and buy what I want than rush into something I'm only 60% happy with. Have loads of fun trying though

[quote name='ivansc' timestamp='1447155155' post='2905277'] Depends how you interpret "dud". Presumably you did look at the bass when you bought it but assumed that you could fix the bent neck. Unfortunately in my book that would imply that you were aware of there being a problem and accepted the instrument warts and all. But I would still go back to the bloke, show him the issue and see if he is prepared to make an accommodation with you. Good luck! The sad thing is, he probably sell it like that in good faith. [/quote] this is about right. By examining the bass there is a fair argument you accepted it's condition, or at least that's what he might argue in court. I think he probably did sell it in good faith but it is hard to know. You can't really prove he knew of the fault and he can't prove it was sold as seen, unless he had something written in his ad on ebay. In that situation the best thing is to try and resolve the thing by talking. I had a similar situation when a Takamine I bought through ebay arrived with the pre amp not working. I contacted the seller who insisted it was working when it left. I got quotes for a repair and he paid £100 towards it. It turned out to be a broken connector in the pre amp which I repaired myself but by talking we avoided any dispute. I've also been through the ebay dispute resolution process which was painless and I got my money back from ebay. I assume they then got it from the vendor but that was their business. I got the impression that the right is assumed to be with the seller. Check what ebays conditions are though, there is probably a time limit. Good luck, it is horrible to be in that position.

[quote name='dave_bass5' timestamp='1447081469' post='2904656'] As xgsjx said above, i too always just thought 8 ohms was 2/3 of the full output, but obviously thats not the case. [/quote] It was a good question. obviously the power can be 2/3 or 1/2 depending upon the power supply. I think my old MAG600 was about 2/3 and it isn't a bad rule of thumb but that's why it isn't a fixed proportion. theoretically double but a bit less in practice.

Hi Dave, you have the answer already from Chienmortbb. I'll see if I can explain differently. An amp can only produce a certain maximum voltage into a speaker and that determines it's power output. However if you reduce the ohms the speaker will take more current and more power with the same voltage, so if you have an amp that produces 100W into 16 ohms it will produce 200W into 8ohms. Theoretically this means the amp could go on doing this so 400W into 4 ohms and 800W into 2 ohms. The problem is that this needs more and more power from the amp and the current demand keeps rising. Eventually either the amp gives up and goes up in smoke, automatic protection kicks in, or the power supply inside the stops making extra current. Usually the power supply is the limiting factor. Power supplies are often expensive and if they are transformer based really heavy. This is why most amps don't like 2ohms and why they can't produce twice the 8ohm power into 4ohms. In practice I doubt you'd notice the difference between say 350W and 400W so it doesn't matter. That's another story though. So the answer to your question is 'because they have differing power supplies.' On a practical level I don't think you need to choose an amp on the basis of 25% more power, you just won't notice it. *Valve amps work slightly differently as they have a transformer to adjust to different speakers so they will produce the same power if you have an output for that ohmage speaker.

[quote name='chrisanthony1211' timestamp='1446887181' post='2903127'] I know this will depend upon the size of the speaker, but is there any generalisation about how much lighter neo speakers are? I'm thinking about picking up something like an SWR redhead and making it a little lighter! Would swapping out the speakers make much of a difference? [/quote] I'd think you'd be looking to save a couple of kg per speaker looking at Eminence 10's, actually about a 50% reduction, somaybe 5lbs overall. The Redhead weighs in at 96lb so it is still going to be pretty heavy. The other problem is that speakers may not be a direct swap, in fact probably won't be, so you will get a different sound from the original Redhead. In an extreme case you may even get a sufficient mismatch between cab and speaker for the bass performance to be so compromised the speakers could be damaged. If you decide to go ahead then ask someone here to check for you.

Like the OP I've always been a non singer. Humiliated by teachers at school which didn't help but although I could hear it in my head what came out of my mouth was never what I expected or what I heard. I remember several times people playing a note on a piano and asking me to sing it back, I couldn't get close. A few years back I discovered when setting up the PA I could hold a note and sing along if the monitors were turned up. In other words I could sing in tune when what I normally hear was blotted out by the PA. I genuinely can't hear my own voice. Since then I've been asked to do the odd backing vocal and had a go, Things like the doo-be-doos in Chelsea Dagger. No-one has thrown anything yet. The good news is it is getting better. You really can learn to sing, painfully slowly and with the usual two steps forward one step back but you even have muscle memory, once you've nailed something it stays as long as you keep practising it. It's something that seems to come so naturally to most people that you feel like constantly giving up and I'm sure it still isn't a nice sound but just filling out a chorus helps the band and three of us singing ups the audience response. I have no idea what is going on, why I can't sing without a monitor when everyone else seems to have that trick and I'm so self conscious (a rare and salutary feeling for me) when I sing, but if you want it enough keep trying.

[quote name='Dad3353' timestamp='1446683508' post='2901521'] All precious stuff so far, with the different spotlights on the subject adding to the usefulness. If I may, I'd like to have some expert opinions on the rather modern tendency to use, not simple distortion, but outright fuzz on bass, giving a waveform much closer to square wave than sine. Does this not have a bearing on the cone behaviour, as it is effectively receiving almost a DC element for a good deal of its cycle. Would that increase the heat dispersion problems..? Is this negligible, or something worth considering when estimating power handling requirements for speakers..? Please ignore if too far off topic. [/quote] That's kind of true, and I like the idea of different spotlights, often a difference of technical opinion is down to a different perspective or at least answering a different question. For example what Bill says is true if you have a speaker with a crossover and a tweeter, and is the reason why you need to be so careful running a distorted signal through a poorly rated horn. If however you are putting the whole signal into a single drive unit and the signal is reaching the maximum voltage the amp can produce then the square wave will have 1.414 times the energy of an undistorted sine wave. The Cone and the coil will be travelling the same distance in each case so air movement and air cooling will be similar, depending just a little on frequency. However you can potentially have a little more heat to dissipate with a distorted signal and what actually happens will be down to the detailed design of the speaker and the amplifier in question. In practice of course even if you have a pure square wave you will still be producing notes, which will have a loud start and fade with time and then a gap before the next note, even with metal So you may be producing 300W peaks or whatever but the power averaged over a few minutes will be a lot lower, allowing the speaker to cool between bursts of power. Your poor tweeter though may be rated at 30W thermal in a 300W system and if you have a crossover the extra 0.414 of your 300W will be diverted that way so without some protection it is going to smell of scorching.

There's little point in spending £200 on speakers when you can get a used cab for £100. Everyone is giving you the advice I'd give you. Get a used Peavey, preferably one with the BW drivers in. Peavey bass cabs are great heavy things but sound pretty good and are really reliable and crazy value for money. I've got an old 1x15 BXBW here removed from my rehearsal room, I'd happily sell for £75 if you want but there's loads out there. http://assets.peavey.com/literature/manuals/80300395.pdf carriage looks to be about £35 though buy used unless you have an overwhelming desire to build something.

[quote name='alexclaber' timestamp='1446649486' post='2901137'] It's extremely rare to blow a woofer with bass guitar without it sounding pretty distorted first. If something does go pop without any warning overdrive, especially something fairly new, then it's most likely to be a manufacturing fault. Phil, I'd say you've got things the wrong way around in terms of excursion for most half-decent modern bass guitar woofers. Older designs which don't have vented motors do indeed rely on the magnetic gap removing heat from the coil via radiation but most modern drivers have vented motors so getting the woofer pumping back and forth, even if the coil is moving out of the gap, will remove more heat via convection. Also, most decent modern MI/PA drivers use the suspension to limit excursion to reduce the chance of bottoming out or jumping out of the gap and have a decent margin between Xmax (where distortion tends to rise significantly) and Xlim or Xmech (where permanent damage occurs). Bass boost does tend to cause problems though, because most cabs are quite a lot less sensitive at 50Hz than at 100Hz, so you can put a lot more power in without getting a lot more sound out. Also, most cabs are tuned to the 40-60Hz region, which means the impedance is low so much more power actually flows in that region that at 80-120Hz, so you have a double whammy of it taking more volts to create the sound and more current flowing for the volts, so more true power hitting the voice coil. And at that low impedance region the woofer is moving much less because it's operating against the high pressure load of the tuned port, and the port is creating most of the acoustic output, so there's less voice coil movement to pump the hot air out of the motor. [/quote] I was trying to keep it simple Alex, and I'm making the assumption that an 800W 4x10 isn't using the same drivers you use. There are still a lot of ceramic magnet speakers out there that don't have vented motors, though you'd expect it with neo drivers at least. Even so I doubt that the cooling is improved by the coil leaving the magnetic gap. There's also the behaviour of the speaker below the tuning of the port to consider. Surely you aren't saying the speaker runs cooler when the excursion is pushed up by increased power? The OP asked about how to avoid blowing speakers and the best way is surely to avoid Xlim. I wanted to give a few practical tips which anyone reading could take to avoid having to replace speakers. I'm also not sure most bassists would recognise rising distortion in a gig situation with a set of cymbals by their ear, two guitarists going flat out and all sorts of pedals in their sound chain. I'd want the safety of my rig designed in and not dependant upon my noticing at the climax of a gig.

If you want some practical advice, with a bit of explanation? Understanding why speakers blow helps and there are essentially two reasons why they blow early. One is that they overheat and the other is that you push the sound levels up so high that the speaker moves so far the coil comes out of the magnet. The problem is that speakers are most likely to be damaged by the second problem of over-excursion but they are rated for the first problem by their ability to handle heat. So your 400W cabs should be able to handle a 400W amp all day, so long as you don't put bass through them. Sing as loud as you want or play a skinny string or anything above 7th fret on the A string you'll be fine. The problem comes when you go down an octave, making bass sounds needs you to shift a lot of air so you need more power and the speaker has to pump backwards and forwards more to shift all that air. Eventually it moves so far two things happen, either the delicate coil hits the back of the magnet or it moves out of the magnet gap, either way it gets damaged. Once the coil leaves the gap the cooling fails and the rating of the speaker goes right down. Your 400W speaker becomes maybe a 100W speaker. That's usually why they fail. So apart from using much more speaker than amplifier how do you stop it? You limit excursion. 1. Get a filter that stops the deepest bass (like a Thumpinator) 2. use eq wisely. A tweak on the bass boost (say 2 o'clock) will make your speaker work twice as hard. (10 o'clock half as hard) Never go to full bass boost unless you are absolutely confident you have enough capacity in the speaker. 3. watch the effects, an octaver means you need twice the power handling if you are going to play anything lower than 7th fret E. Amp modelling and quite a lot of effects boost the bass, using two in line can push this to unexpected levels. 4. If you want a bassier sound it is often better to cut treble and mids and then turn the volume up. 5. think about keeping the deepest bass out of your rig and putting it through the PA bins. If you really have to have that trouser flapping, deep bass, distorted sound then you are going to have to have more power and more speakers but the Thumpinator or similar will help a lot and they are far less audible than you might expect. BTW I think BFM was spot on, this failure was down to a faulty component and should have been sorted under warranty.

[quote name='Jono Bolton' timestamp='1446455545' post='2899401'] The cab has side mounted feet as well as the castors but even when I lay it sideways on the floor the vibration was still present. The head has just been cleaned out and all the pots cleaned so it's all working, but the noise definitely comes from the cab. I'll check the metal side stripes on the grille as they don't seem to be secured to anything at the front so it's possible they're vibrating. My head is an Ashdown ABM 300 which is reasonably small and lightweight, when I got the cab I tried it out with a Mark IV which may have weighted the cab to stop it vibrating. [/quote] Ok if I have this straight then your head is moving on the top of the cab and you have an audible vibration? My thought is the two may not be caused by the same problem. They may be of course. I had an unpleasant buzzing noise from mine. Upon examination the dustcaps in the centre of the speaker were loose and there was some separation of the corrugated surround from the cone. Not unusual in speakers of this age as teh adhesive becomes brittle with time. I carefully removed the dustcaps and glued them back down with Copydex, which is latex based adhesive. I then stuck the surrounds back with more copydex and used a paintbrush to then seal the whole circumference to the cone with more copydex. The speaker is still working after several years. You should be able to remove the whole grille assembly including the silver strips and operate the speaker without these. That will eliminate them as a cause. You can also remove the speakers which will allow you to go round tapping bits of cab to see where they are loose, if at all. Whist in there check the speaker cables inside aren't buzzing against anything.

Without any measurements to back this up it is fairly obvious that a lot of commercial cabs have a 'smiley face' engineered in. A typical commercial 12" cab has an Eminence driver, often a 'special' built into a small cab. I'm talking mid-range price here. If you look at the Eminence Beta http://www.eminence.com/pdf/Beta_12A-2.pdf it has a marked (3dB) peak in on axis response between 1 and 3kHz . This is typical of a range of commercial drivers. Put it into a small box (typically 1.25-1.75 cu ft, sorry Eminence use imperial units) and you'll get a roughly 3dB peak between 100 and 200Hz. So the midrange gap between 200-1000Hz is 3dB down from the rest of the speakers response in a 'normal' speaker. If you aren't used to anything else then a speaker without the same midrange dropout will sound middle biased. Which is 'wrong'? Well neither of them, people like the sound of a midrange suckout and if it isn't inherently built into the cabs response dial it in with eq, or with their bridge/neck pickup settings. Other people want to start with a flat response that they are then in charge of. That's what people asked for when we started this project and I think we met the design brief you came up with. I'm not being defensive I hope. The problem with a self build is you don't know what it will sound like until you build it and most people can't 'hear' a speaker from a graph and a set of figures. I want people to have a good idea of what they'll get. I think it's fair to say this will be a very open, clean sounding speaker with a bit more deep bass than most speakers but without the artificial warmth of many commercial units. It'll go very loud without stressing, respond well to eq tweaks and yes, you'll notice some midrange that might not be there in your old speakers. At some stage I'd love to run some measurements on commercial speakers and I'm planning on coming up with an 'old school' speaker at some stage.