Phil Starr

The most common cause of buzzes if it isn't something loose are the dust cover (dome in the middle ) coming loose or the corrugated surround coming loose. both can be re glued with copydex latex adhesive. Alternatively it could be a small tear in the cone which can be 'layered up' with copydex and tissue paper. I assume youve checked that nothing is touching the cone and it isn't the rattle of something loose in the cab. Good luck, I hope it isn't something too serious.

[quote name='therose789' post='1241787' date='May 23 2011, 04:01 PM']can i run a 4ohm cab and two 8 ohm cabs at the same time from my ad200? i dont have that amount of cabs, im just wondering? if so what will it do? kill people?[/quote] Since your 4ohm seems to be an 8x10 that plus two more cabs is more likely to kill your back. You surely don't need extra volume? [quote name='obbm' post='1241902' date='May 23 2011, 05:15 PM']From Adrian Emsley - Tecnical Director at Orange Music Electronic Ltd - 24 April 2008 in answe to my question. It confirms what has been previously said. 1 x 8 ohm cab = 8 ohm socket 2 x 8 ohm cabs = both 4 ohm sockets 1 x 4 ohm cab = either 4 ohm socket Regarding the original post Run the 2 x 8-ohm cabs in parallel Put these in series with the 4-ohm cab to make 8-ohms. Run the lot from the 8-ohm output.[/quote] This is the spot on technical answer if you want to go ahead. It would be the sort of thing that would be fun to try if you have the cabs sitting around and an hour to kill and you know how to wire cabs in series. The 'mismatched' 4.something arrangement wont give you more power as you have a valve amp. It may be quieter as it distributes the power between the speakers in an odd way. Who knows if the tone from either arrangement will 'work', there is more to matching multiple speakers than just worrying about ohms.

[quote name='deepbass5' post='1240034' date='May 22 2011, 09:38 AM'][b]No don't do it[/b] is the answer these mass produced cabs are made from fairly cheap light weight stuff anyway; it is the speakers that make up the weight. I would suggest changing the drivers to neo's but that would cost as much as a good second-hand cab with Neos in. Don’t mess around building something buy a quality second hand one so all the design calcs are right. You will end up with a Dogs dinner and have spent a lot of time and money and still not be happy. probably change the sound too[/quote] This is pretty much right, you'll go to a lot of effort to save 5kg maybe, the weight is in the speakers which are what gives you the sound you like. You could try making two 2x10's which would be lighter obviously and would also give you the advantage of a vertical stack with better dispersion but this would also be a lot of effort for little advantage. 4 heavy speakers are never going to be a lightweight option, if you like your sound then you are stuck with this beast and if you want lightweight then you have to completely re-think. Sorry

An alternative could be to wire a switched jack into the speaker cable. This could be wired to either switch the internal speaker out of the circuit when an extension is plugged in giving a different tone and the possibility of more volume if your extension is more efficient. Alternatively the socket could be wired so that any speaker would be connected in series with the internal one; this would allow you to use a 4ohm extension along with your existing speaker.

Good luck with that,I lived in Reading for 28 years and it sounds like a fantastic project.

Hi Phil, ask yourself how much you need this extra speaker on stage. If the answer is that you are happy with the stage volume and sound then just get a speaker for practice. If the answer is that you want to change your stage sound and/or want to use a smaller speaker for other gigs and leave the 4x10 behind then OK. Forget about speakers having a sound related to their size. Cone size is only one factor in a speakers sound and not even the most important one. 10's from different manufacturers have different sounds, as do 12's and 15's with things like 'punch' and 'bottom' overlapping. Mixing speakers isn't good or bad as some people seem to imply but can be unpredictable. The main feature that determines a speakers sound is the little peaks and troughs in it's frequency response. If you add a differnt speaker then it will have it's own peaks and troughs. Where they coincide there will be a bigger peak but most of them will probably not coincide and the effect will be a levelling out of the response. The sound will be smoother but will lose a little of the character of each speaker. Imagine if you used two graphics and on one you boosted 1kHz in the mids and on the other you cut by exactly the same amount. The overall effect would be nothing. there are also beaming effects by using multple drivers and interferences due to the spacings of the drivers but that's a little complex for a shortish answer. so if you love the sound you are now getting then get a 2x10 which has identical drivers or that sound is going to change. If you want a change of sound then don't get hung up on speaker size. I'd go for a cab that sounded good first of all. I practice harder when it sounds good and so do most of us. If it sounds good and you can use it for small gigs then your back will thank you. If you want deeper lows or more highs look for a cab that does this better than you current cab but don't expect it to be too dramatic because of the levelling off effect. the biggest effect will probably be having the speakers nearer to ear level. You'll hear yourself play more clearly and probably turn down which will clean up your stage sound, always a good thing. Finally think about impedance and efficiency. If you use an 8 ohm cab with your 4ohm cab then the 4 ohm cab will take twice as much power as the original cab and you'll be running the amp into 2.7 ohms. can your amp cope. Run into two 4ohm cans and the power will be shared evenly but you will potentially reduce the power going to the 4x10. Make sure the speakers are similar in their efficiency. The 4x10 is probably pretty loud and if the new speaker isn't efficient you wont hear it when you run them together. Cheers

[quote name='david_l_perry' post='1219538' date='May 4 2011, 09:34 AM']Indeed....i had a pair of EA CXL112 transmission line cabs, great little cabs, but I had problems with one of the drivers. when I took the driver out and checked out the inside it was very apparant this is not a true transmision line cab (it was just a long shelf port), but more importantly, the '8ohm' cab is loaded with a 4ohm driver.......MY mark bass head kept shutting down with the pair of them and suddently it became obvious why.......it did explain why they are loud '8ohm' cabs.... EA do make good cabs, but they are just not as described......[/quote] In their current literature they describe the cabs as 4/8 ohms, do they have twin voice coils?

there you are then EA claim that both sets of ideas are true at the same time and their cabs have all the advantages. [url="http://www.eaamps.com/index.php?p=translines&m=tech"]http://www.eaamps.com/index.php?p=translines&m=tech[/url] Mind you, there is no way this is a transmission line. the line itself has to have the cross sectional area of the cone at the speaker end to avoid pressure changes and as Bill says is 1/4 wavelength so that's 6 cu ft packed inside a 2 cu ft box. Truly amazing! And 103dB sensitivity at 45-12,000 Hz with no excursion limiting at 200W, obviously the laws of mere physics no longer apply at EA. [url="http://www.eaamps.com/index.php?p=wizzym&m=products"]http://www.eaamps.com/index.php?p=wizzym&m=products[/url] These may be great speakers but I wish people would be honest

[quote name='Bill Fitzmaurice' post='1219340' date='May 3 2011, 11:17 PM']Transmission lines are 1/4 wavelength resonant pipes. The 1/4 wavelength resonant frequency coming out of the terminus acts much like the port in a bass reflex. The line is stuffed with damping material to suppress the harmonics of the pipe frequency. The advantage to a TL is that below the pipe frequency response rolls off at 12dB/octave, like a sealed cab, rather than the 24dB/octave of a bass reflex, so you get sealed cab 'tightness' with reflex efficiency. The downside is that they need that 1/4 wavelength pipe, which is 5.7 feet for 50 Hz, 7 feet for 40Hz. They're just too big to be practical for electric bass.[/quote] I said there was controversy. Strictly speaking what Bill is describing isn't a true transmission line, but it is the only practical version you'll see today and the one the computer models work on. The original transmission line was just as I described an attempt to absorb all the rear radiation with a zero resistance at the far end of the line to prevent pressure being reflected back along the line where it would arrive out of phase with the speaker cone. Lots of magic went into stuffing the line to achieve this. In the 70's people questioned this and said that the cab acted as a reflex cab in exactly the way Bill describes. Supporters of the original theory will point out, quite correctly, that measurement of the output of the port/termination of the line is much lower than you would expect from a reflex port. The computer models don't predict measured bass response particularly well for these speakers. I'm agnostic about this and ultimately a bit sceptical about the claims for transmission lines. there are some nice sounding TL's in the hi fi sphere but I reckon a lot of this is due to a well behaved impedance load and the massive internal cabinetry which cuts down on a lot of cabinet resonance. In any case Bill is right, there is no real place for TL's in electric bass cabs.

Hi Gus, great question, or rather questions. It should keep us going for months. the easiest one to answer is your transmission line question. Although there are some technical controversies over these the whole point is to absorb the rear pressure and to stop it reflecting back to the speaker so you lose all the energy from the rear of the speaker and you have a decent mass of air in the line. Transmission lines promise lower resonance and smooth low end response with good transients but low efficiency. Older speakers (I used to design speaker cabs back in the early 70's) tended to have limited power handling due to inferior materials available for the voice coil assembly and the expense of amplifier watts. This meant they were designed to be as efficient as possible by packing a lot of voice coil inside as powerful a magnet as you could afford. The cost of this is that excursion (Xmax) was usually very limited. Speakers weren't really designed for bass specifically anyway most of the time. Excursion limiting wasn't a big issue if you were limited by amp power. Thiele's research wasn't widely known about either, and a lot of design was hit and miss, so a lot of speakers were put in cabs that we now recognise as too small resulting in a marked bass hump in the frequency response which made them seem loud and warm sounding. I suspect this could be the reason for the difference between your cabs.

[quote name='Arrakis' post='1215856' date='Apr 30 2011, 02:58 PM']Ok thanks for the replies. Its going to used in a supportive role rather than a lead sound playing detuned stoner/doom pushing out lots of fuzz/drive going to be running in conjunction with a 2x15, the 2x15s dont especially sound great at pushing out the fuzz. Now I have had a very mixed response about this on various forums including this one, theyre going in a Matamp Retro 4x12, now Ive phoned the factory and their view is that it should be fine to swap out the guitar speakers for bass drivers, now before people start saying thats wrong I have also spoken with someone whos done it with good results so my point to this thread is to basically find out what drivers on the market are good for specific styles/sounds etc[/quote] [quote name='voxpop' post='1215866' date='Apr 30 2011, 03:08 PM']Now this could be utter bull, but from my limited experience of swapping out speaker Celestions have a rough rock type sound and Eminence have a cleaner slightly brighter sound. (possibly)[/quote] This kind of illustrates the problems designers have. We don't have a lot of words to describe sounds and those we do are ambiguous. For me fuzz is a certain type of harmonic distortion as created by a fuzz box but it could be any sound you think of as fuzzy. It is relatively easy to work out why a musician describes a sound the way they do after the fact. For example the Eminences sounding 'brighter and cleaner' is largely due to the big peak in frequency response at around 2-3kHz that many of their speakers display and this in turn is caused by the way the cone behaves under breakup. It is much harder to work the other way and create a sound from a verbal description using your knowledge of the science. Much of what bass players think of as 'musical' in a cab is often actually down to a distortion of the sound their guitar makes. Just swapping your guitar speakers for bass speakers will 'work' as the guys at Matamp are telling you in the sense that they will make a sound and you can put lots of bass through them. It may be that they sound how you want or they may not. How the bottom octaves sound depends upon matching the cab and the speakers, if your mate had the same cab as you and you put in the same speakers as him then you should get the same result and you don't need us to help. If you put any other speakers in or your cab is a different size or shape then the results are unpredictable without much more information. The bass could be very thin or very overblown and resonant depending how your speakers match. It sounds as if you really want a lot more upper mids/top to me and the eminence Delta's and Basslites both have peaks in this area so might give the sound you want. I don't know if they will work well in your cab or if they will go with your other speakers. I hope you realise people aren't being awkward. It is just about impossible for anyone to say 'this is the speaker you want' because there are too many variables and none of us wants to be responsible for you spending a lot of money and not getting the sound you want. If you want to go ahead and take a gamble then you might be lucky, you can always put the guitar speakers back and sell the new ones on ebay if it doesn't work out. You might be better tracking down Alex and listening to some of his cabs and homing in on the sound you want since you live in that area. Good luck

The computer modelling programs are great if you know what you are doing because they cut down the calculation time but if you don't understand the theory then they can easily mislead you. Qts is very low for these speakers which means that any cab you build will be overdamped and will have a bass that tails off very noticeably. Fs is high but Celestion make bass speakers which have a high fs and it seems to be true that the fundamentals aren't as important as the harmonics in the way we hear somaybe that's how they get away with it. Anyway these look like midrange speakers to me too whatever the seller/manufacturers say. Another problem may be the amp. I love those old Peaveys but you seem to be operating 6x 8ohm speakers in parallel giving a 1.3 ohm load. The amp won't do this and will power limit to protect itself. You could try wiring the cabs internally in series (16 ohms each) and then running them in parallel giving a load of 5.3 ohms which the amp will be happy with. Alternatively go back to the supplier and tell them the speakers are not bass speakers and ask them what they can do about it

[quote name='Arrakis' post='1211447' date='Apr 26 2011, 09:04 AM']Well the reason i want the extra cab is that the 2x15 isnt particularly good at dishing out the fuzz, I like more drivers for that they seem to sound better, the 8x10 i used to have sounded great for that. I was contemplating trying to make a new baffle for 10s but figured it would be easier to swap out the 12s for bass ones though obviously this doesnt seemto be such a gd idea. As for the 2 cubic feet, Matamp Retro cabs are pretty beasty in size so perhaps putting 2 drivers in with the other holes blocked or on a new baffle would work. Not sure I fancy running the 2 amp ideas as its more to go wrong and lug around (says the bloke wanting 2 massive cabs lol) etc What I dont understand is that I have used bass 4x12 before of the same dimensions of this cab, a marshall and a old trace elliot cab both branded bass 4x12 both the same size... so whats up with that?[/quote] There is probably no technical problem in changing the drivers for bass ones other than just choosing the right ones. If you start with a ready built cab then the choice is going to be limited. Most bass cabs are ported cabs for the very good reason that this is the best way of getting a decent level of bass out of a relatively small cab. Tuning a ported cab is critical for a decent sound and you'll need to get to grips with all this to get a good result. If you tell me the size of the cab I can suggest some drivers that you might consider. The internal dimensions would be good. You should realise however that there may be some woodwork involved in adapting the cab. Four 12" bass speakers are going to cost you £200-300 for anything reasonable and more if you go for lightweight or better quality. You'd probably get as good a result with less hassle by selling your cab and putting in that extra for a bass cab you can try before buying. Not all 4x12's or even 4x10's sound the same or give the fuzz you want. On the other hand you may enjoy fiddling around with speakers and you'll learn loads in the process. If you can afford £200 and don't mind if it is only a partial success then you'll find loads of people here to give advice. Over to you

It's almost never worth trying to adapt an existing cab like this because of the problems of matching speaker to cab volumes. Cabs with the original drivers are usually worth more than ones with replacements anyway, even if the replacement is an 'upgrade'. That doesn't mean it can't be done however. Why do you want to do this I wonder? Do you have a sound in mind that you are trying to achieve? Do you think you need extra volume? Is it because a full stack looks cool, you could always take the 4x12 and not connect it! You wouldn't be the first person to do this by a long way. Speakers don't have a 'sound' which is solely ,or even mainly, connected with their size. Just substituting speakers will be unpredictable in the sound you achieve unless you know a lot about interpreting data and speaker design, even then there is still a bit of luck involved, thought he more experienced you are the luckier you get. I reckon that if you tell people what you are trying to achieve you'll get some good advice.

Try Rapid [url="http://www.rapidonline.com/Electronic-Components"]http://www.rapidonline.com/Electronic-Components[/url]

To get decent bass out of a speaker the speakers and cab have to be matched as Mr Foxen has said. This rather than the brand should determine which way to go. I'd avoid using 4ohm speakers without checking Xmax which is the excursion. 4 ohm speakers generally have shortened voice coils and wimp out earlier than 8's. In any case you want two 8's to get 4ohms.

The centre chamber will act as an acoustic filter removing some high frequencies from the two centre speakers. they claim a resonant centre chamber with side ports but for this to work properly the centre chamber would need to be sealed at the front, have they removed a panel for the photo I wonder? This sort of design was worked out before the work of Thiele was widely known and probably is technically dubious. A sort of "throw lots of big speakers at it and make it look good" approach.

The Me 15-200 is exactly that a 15" 200W speaker Qts 0.59, Vas 224 l,Qes 0.67 fs 46Hz if you want the T/S parameters. It was probably made in the early 1990's

Since you've tried so many rigs it's actually unlikely to be that. I'll bet the audience isn't hearing what you hear on stage, that would defy the laws of physics by the way. For a bassist the grass is always greener on the other (audiences) side. Either get a mate to play while you listen to your rig or get a female jack/jack socket and join your two longest leads together and get right out there. If you are still unhappy with the sound you have to listen to other bassists and plump for ones who have the live sound you want. It could be the rig but it could be the guitar, the strings or eq. You've been trying a lot of respectable gear, I suspect youre just not hearing what the audience hear.

Hi Jack, I think Mr Foxen is right, if you want that exact sound then a 1x10 or 2x10 will give you the sound with portability and a sealed cab is the easiest build anyway so long as the box is airtight. I wouldn't worry too much about the impedance unless you are using a valve amp. The few dB you lose shouldn't be a problem in a recording situation. Sealed cabs typically have better controlled bass with better transient response. The cost is a higher cut off point with a longer slower roll off in output below that along with lower maximum output. When you are recording you can use eq to lift the bottom end and this works well with the 12dB/octave roll off of these cabs. You also don't really want a lot of high power fundamental in a small room. The 'problem' with multiple drivers is that the sound travels different path lengths to get to a particular point. This means that for frequencies where the speakers are spaced roughly a wavelength apart or more the sound from adjacent speakers might be arriving out of phase and cancelling or in phase and reinforcing each other. They get very directional at high frequencies and a lot of highs get lost. this gives them their 'vintage' sound. If you are mic'ing closer than the diameter of the speaker then you are effectively mic'ing the speaker and not the cab. You need to find out if it is the cab sound or the specific Jensen driver that you like the sound of. I've got a little digital recorder that I use fior recording gigs/practice. I'd take it out with my normal recording mic and go round the shops recording samples on the cabs they have on offer to see what sounds i could get, then I'd have a better idea of how critical a particular driver is.

I'm surprised you haven't been inundated, Your best bet is Lemonrock where you can check out dozens of local bands, listen to mp3's of most of them and check their song lists and diaries. If they'll travel Snappa (not my band)are a great party band who are totally professional but you'll probably get someone more local. Good luck

No experience with the cab but I have a Mag 600 which has been good as gold. Ashdown have great after sales, really helpful.

Isobariks are borrowed from hi fi designs, 'Normal' speakers operating in a sealed cab change the air pressure as they move to and fro'. putting a second speaker behind with an air chamber means the radiating speaker is operating under constant pressure (hence the name) and promises more linear movement of the cone and higher fidelity. Linn made particularly successful speakers this way. Even for hi fi there is little real advantage in isobariks and they remain a niche product. For bass it is just mad, twice the weight and twice the price for a very similar result. Just as Bill says. You'd get a better result by just using a better single driver.

[quote name='LawrenceH' post='1177372' date='Mar 26 2011, 05:12 PM']Also, incidentally that graph is very revealing about axial rotation on the string movement. I assume that the rise-dip-rise response on the 1st harmonic (or 2nd, depending on preferred nomenclature!) is because the plane of string vibration shifts from horizontal to vertical back to horizontal in relation to the pickup poles. Makes me realise that there's another potential source of audible 'beats' to a note, on top of any pitch-based phase interference (as in when tuning by harmonics). It also makes me think that a volume drop in low frequency harmonics in my slap playing v fingerstyle is probably because I'm hitting the string too vertically, and I should aim for a different angle of string attack to better excite the pickup. Who'd have thought that a frequency response graph could teach you something about playing technique? [/quote] It's an interesting graph the even harmonics are showing a very different decay to the odd numbered harmonics, I wonder why. I'll bet there's some sort of series in the maths. Back when i taught science we used to stretch a long steel wire over a bench and watch the vibration with a strobe light. You could clearly see the nodes moving as the vibration decayed.

I can think of several good reasons why effects should change with volume. One is the equal loudness effect which Alex Claber has recently written on. Basically (no pun) as volume increases you hear bass and treble better so it sounds the same as if you had adjusted your EQ. At high sound levels there can be an audible doppler effect if one speaker is trying to reproduce all the frequencies. Also at high frequencies the speaker will become less linear as the voice coil moves out of the magnet gap. Fuzz involves extra high frequency energy and this can overload a tweeter or kick in the protection circuit. None of this helps though as you would have to experiment to find the best settings at any given volume for any given speaker. At least you know you aren't imagining this effect,