Phil Starr

Just got my weeks gig list from Lemonrock, for those who don't live in an area where Lemonrock is active it's an emailed list of most of the pub gigs in a 15 mile radius. A year ago there would have been 25-30 gigs at this time of year. This time it's down to 14, two of them are open mics and five are solo artists with backing tracks. The remaining seven bands all describe themselves as rock covers bands. One week doesn't prove anything especially this time of year but I'd say it ties in with my feeling of fewer and fewer gigs. Lot's of local music pubs have closed or been converted to restaurants round here, however a few of the music pubs are packed and thriving. Is this decline inevitable? Is it just that we need to serve up something other than rock covers? Could the pubs do a bit more promotion into their events, and would that help fix things?

I've been involved in a number of start up bands and am just about to have another go. Both bring their challenges but i think you'd be foolish to make assumptions without an audition and a lot of chat. The experienced player is likely to bring a lot of extra skills, not least that of being able to play in a band, all those practical things of coping with a singer who goes for the wrong verse or the drummer breaking a stick and so on. Bedroom players often keep fairly poor time at first and get flustered when a mistake occurs. Far too many experienced players at my end of the feeding pool bring a lot of inflexibility over what and how they play however, wanting to recreate their old band and wanting to use the songs they have nailed rather than learn anything new. Against that you have to set generally higher skill levels and a huge back catalogue of songs (I only ever play covers, well so far anyway), decent gear and often good stagecraft. The less experienced player can find adapting to a band tricky, stagefright can be a problem as can all the practical things, like adjusting your tone and volumes to suit the band rather than what sounds good at home. They'll have trouble moving from song to song without a break, sometimes stamina and all sort of little things. It's probably going to take longer to get them rehearsed up to the levels you'd like. All of this can be sorted out in rehearsal though. It quickly becomes fairly clear if you've got a grumpy old git (I'm 64) who can't change or a youngster who isn't up to the mark. You just have to be honest about what is expected. All the experienced players were once joining their first gigging band. Most of it is about personality though, if someone is willing to give it a go and work on what they lack, relishing the challenges a new band brings then you can make it work whatever their age and experience.

Glad to see a happy ending. The power handling will not be affected as all the speakers are still sharing the power equally. As you are now working through a two ohm cab it will be worth using a high grade Jack lead to connect the cab to the amp. Operating into two ohms means you need higher current handling. Jack plugs will struggle with two ohms and if you can adapt the cab to use speakons then that would be worth doing for long term reliability.

[quote name='JPJ' timestamp='1482793312' post='3202797'] Years ago, I had an Ohm combo, can't remember now if it 80 or 120 watts 1x15, with a five band eq, sort of graphic but using knobs rather than sliders. Anyway, not knowing anything about impedence etc I added a 1/4" jack socket 'in parallel' with the integral speaker and ran a second no name 1x15 cabinet underneath it I'm not suggesting this is something we should all try, but sometimes, the maths and reality don't exactly align and you can get away with something the science says you can't. [/quote] Not really, the science worked perfectly. You lucked out in that you (probably) had two eight ohm speakers and an amp which was happy with a four ohm load. It wasn't that lucky, the majority of speakers are eight ohms and just about all solid state amps are happy with four ohms. The OP knows they won't be lucky in this case as the internal speaker is four ohms.

Probably but your biggest problem is the tweeter/crossover which I know nothing about. I think you have four 8ohm speakers in there and they will be wired in series/parallel that is two pairs of speakers wired in series and then the pairs wired in parallel. Simply wiring the four speakers in parallel will give you 2ohms. The only problem will be the crossover, if it is a simple high pass filter it will still protect the horn, if it is a 'proper' crossover it will operate at the wrong frequency for the 2ohm bass units.That will change the sound of the cab. If you don't need the horn then you could just disconnect it and the crossover.

That's right, they probably aren't the same model even if they are from the same manufacturer and the same configuration. they probably won't sound alike in a number of ways. Perhaps if you tell us the make and model(s) and how you want to use them we could give more practical advice.

[quote name='Bill Fitzmaurice' timestamp='1482411588' post='3200280'] I repeat: [b]You can blow a speaker using an amp rated at half the speaker rating, you can use an amp rated for ten times the speaker rating with no issues.[/b] [/quote] Whilst technically true this isn't helpful advice stated so baldly. [b]You can blow a speaker using an amp rated at half the speaker rating, [/b]yes but only if you exceed the excursion limits of the drive unit. Most designers are aware of that and whilst a theoretical possibility it is less likely the lower the amplifier power. [quote name='Bill Fitzmaurice' timestamp='1481819614' post='3195449'] If this was an issue reports of blown drivers would be rampant. [/quote] [b]you can use an amp rated for ten times the speaker rating with no issues.. [/b]But only if you keep it turned down. A 3000W amplifier is only a 300W amp if you turn it down to half (10dB) but turn it up full and in most cases you'll end up with a blown 300W speaker. Mistertee the truth is that there is no way anyone can guarantee the reliability of an unknown combination of speaker, amp and crucially bass player. There's always a statistical chance of something failing as there is with any equipment. (our supposedly reliable VW Golf has just given us no end of trouble) if you do something stupid and use gear outside of it's design parameters it is more likely to fail but you might be lucky. Matching the amp to the speakers or having a little less power in the amp gives you a 90% or better chance of reliability for a long time. I'd use the car analogy again; if you fit a huge engine into a car without modifying the brakes and suspension you might still drive it safely, some drivers can break even a family hatchback if they drive badly enough but drive the factory model as intended and you are probably going to be OK.

First of all thanks to so many people for adding to this thread and being so constructive. I hope people are enjoying it and finding it informative. I'm going to throw in another issue. the positioning of the pickup. The only place on the string which shows the full movement of the fundamental (deepest) note is at the 12th fret. Nearer the bridge you get more of the harmonics which is why bridge pups are always less bassy than neck pups. Somebody has just put up a link to an app that models this. you can move the position of the pup and see how this affects the output of the pup. I'm pretty sure the app doesn't allow for any frequency irregularities in the pup. Set the neck to 34", the string frequency to 31 ( and the pup position to 17" (yes I know that's in the middle of the neck) now slide it down to a practical 6" position and you can see the bass output drop off. That's showing a significant drop in output of the deepest note. 3db drop means half the excursion. [quote name='ikay' timestamp='1482356646' post='3199907'] Pickup position is a significant factor as well. Have a play with this app and test a few positions and multiple pickup combinations etc. Switch on the 'fundamental frequency marker' as a reference point. [url="http://www.till.com/articles/PickupResponseDemo/index.html"]http://www.till.com/...Demo/index.html[/url] [/quote]

[quote name='ikay' timestamp='1482356646' post='3199907'] Pickup position is a significant factor as well. Have a play with this app and test a few positions and multiple pickup combinations etc. Switch on the 'fundamental frequency marker' as a reference point. [url="http://www.till.com/articles/PickupResponseDemo/index.html"]http://www.till.com/...Demo/index.html[/url] [/quote] That's a fascinating app, thanks for posting it. I've long been aware of the phenomenon but too lazy to do the maths. I'll add this to my favourites. I hope you don't mind but I'm going to put it onto another thread I started as it is highly relevant. thanks again.

[quote name='karlfer' timestamp='1482309156' post='3199316'] Genuine question. Why are big old speakers more efficient? [/quote] Because they had to be. It was the primary design goal. With old materials it was hard to get high power handling, even as late as 1970 he average 12" speaker often only handled 25-50W. Amplifiers were really expensive and 100W was as big as most went. Drive units in those days often boasted 100dB/W or higher efficiencies as opposed to the typical 96db of a lot of todays units. This was achieved by ever larger magnets, light cones and short voice coils. Bass response was correspondingly poor. In cab design two techniques broadly were used to raise sensitivity. A lot of PA designs used horn cabs to increase efficiency and I remember a lot of touring bands going out in the UK with huge stacks of Martin horns. The solution for guitars and bass were to use multiple speaker units like the Marshall 4x12, usually used in pairs. The efficiency of a speaker increases with the square of the increase in radiating surface so you get a 3db increase in sound with double the no of speakers for the same power. For bass this led to 2x15's and 8x10s. Each 10" speaker may only handle 50W but the cab handles 400W and gives you 9db more than a single speaker for each of those watts. Each speaker may only have a couple of mm excursion before distorting but together that's all they need. A lot of rock conventions were the result of a bid for ultimate volume. Guitarists used speakers with huge midrange peaks to get extra volume. Bassists adopted underdamped cabs with a bass peak for the same reason. Singers adopted falsetto or the upper part of their range to cut though over all this sound. To an extent the conventions of rock were determined by the technology of that time.

There isn't any difference in valve watts and SS watts, but there is a difference in the way they are usually used. When you play at 200W that means you are actually playing with peaks of 200W, that moment when your pick or fingers hit the string really hard on your loudest notes. Until you pick the next note the sound dies away and the next note might be one you want quieter. If it is half the volume that's 10dB down and actually only uses 10% of the power or 20W. Once that note has died down to half its volume its only using 2W! The average power of an amp flat out is only a few watts. Let's imagine you are operating at a very loud average of 10W with peaks of 200W. You want to turn up just a tiny amount, which is 3dB. Conveniently that's double the power. You are asking for 20W average which both Valve and SS amps will be happy with. The trouble is that the peaks are now 400W. A 200W valve amp will still only give 200W and so it will distort the loudest bits. the thing is that it will do so in a way that sounds OK, Some people even love valve distortion and seek to make it by turning their amps right up. With a SS state amp the distortion is liked by almost no-one and sounds awful. So, valve amps are often deliberately turned right up to get distortion and are louder because they are turned up with higher gain on average. They are also usually used with big old speakers which are more efficient. So as far as protecting your speakers a 200W valve amp is no different from using a 200W SS amp, you'll probably just be turning it up louder to get some valvey distortion.

First of all I like the car analogy for people who are not technical.Just as a more powerful engine will have a predictable effect fitted to the same car once you start changing speaker cabs the engine power becomes just one of many things you'd need to consider. Power isn't unimportant but you wouldn't start looking for a new car based only upon the horsepower of the engine. It's also true that a lot of sound engineers like a little more power in their amps than speaker watts, I do myself. I don't in my bass cabs. If I'm engineering sound I do so from the best seat in the house, I hear everything. Any clipping in the vocals sounds awful and there is almost no bass content in the voice. All my mic channels bar one are subject to filtering out the bass, I've also got metering on the output which I can see all the time, limiters protecting the speakers and control over my dynamic range. What I want is lot's of clean output, I'm not going to run my system into distortion or blow my speakers so overhead is critical to me. When I'm playing bass I've no control over the rest of the band and I may be forced into playing louder than I'd like. I can't hear my bass amp clearly in most venues because I am too close to the speakers and I'm not going to notice even quite high levels of distortion. I'm also concentrating on the drummer and the rest of the musicians in the band and my own playing. I'm putting out a lot of deep bass into the speakers so I'm pushing them into high excursion levels. What i need to know is that however hard i push the power up I can't overdo it. It makes more sense to me to know I can't destroy my speakers and have one less thing to distract me so I tend to have more handling ability than amp power. My set up can overpower the drums so I know I have the volume I need.

[quote name='Bill Fitzmaurice' timestamp='1482005633' post='3196969'] Doesn't everything? A goodly percentage of members there suffer from advanced cases of Dunning-Kruger effect. That fact isn't lost on amp designers, so most have low pass filtering in the pre-amp as part of the pre-voicing EQ. Where you're most likely to have an issue is with a separate pre-amp/power amp configuration, and then only if the pre-amp designer didn&'t high pass for whatever reason. [/quote] I had to look up Dunning -Kruger, part of the human condition I suspect I think your point about the pre-power combination is really important. There are a few people out there using a PA power amp with some sort of pre. Most PA amps are engineered to be flat down to the limits of hearing sometimes with switchable filters. Often users are attracted by the almost unlimited power of the PA amps so they are using kilowatt amps which may go down to 20Hz with a pre amp which may have little or no filtering. Fine if you know your technical stuff but not safe for speakers if you don't. I'm sure you are right about most bass amp designers being aware of the problem and having a little HPF intrinsic to their designs. Like most of us I've owned a series of amps, I always read the manuals and download them when I buy a used amp. I've never seen any information given on low frequency response given in the way it is routinely for hi fi and PA amps. It must be there as you say, otherwise we'd be seeing a lot more blown speakers but I couldn't tell you if there is any HPF filtering in my MB Tube or my Hartke for example. Wouldn't it be great if all bass and pre amps came with a switchable filter?

[quote name='alexclaber' timestamp='1481900888' post='3196140'] You can't filter out these frequencies with passive speaker level components, it has to be done at line level with active components. Most bass amps have some kind of high pass filtering and most power amps have switchable filters. [/quote] The trouble is that this information isn't shared by a lot of manufacturers or is buried in a lot of other information [quote]The strange thing about this issue, is that the worst problems I've had with cone over-excursion were with cabs which were tuned to 31Hz, so you were never driving them with frequencies below the tuning frequencies. You'd think from reading Phil's original post (which is broadly correct) that these low tuned cabs could never suffer such problems. That experience set me down the road of finding out what really matters with the inputs bass guitar cabs can handle and also the sounds they're expected to generate. It's much more complicated than you think! [/quote] That's fair comment, I've admitted up front that this is moderately complex and I'm avoiding being too technical so I am simplifying. Tuning to low frequencies does exactly what Alex says, with my own recent design lowering tuning sends excursion way up elsewhere and reduces power handling unacceptably in frequencies which a bass is much more likely to produce.

[quote name='karlfer' timestamp='1481886392' post='3195925'] This is beyond me. Most things are beyond me. Am I to understand that a Markbass LM800, run with no effects, no compressor (I never use either) all EQ points noon, VLE/VLF (whatever they call them) off, that the maximum average ? I'm achieving is around 80 watts? [/quote] Depending upon the way you set up and play it could be even less. If each note fades to a quarter of it's initial volume that's half the volume on average which only takes 1/10th of the power, and then you have rests in your playing

[quote name='ead' timestamp='1481894569' post='3196049'] Don't know whether it's urban legend or not, but I have heard suggestions that speakers should be stored & transported on the backs so the sagging effect is minimised. [/quote] I've heard the reverse, though modern materials are so much better that I wonder now whether that is right. We used to move speakers with a shorted jack plug in. The hope was that the back emf would dampen movement in the van.

[quote name='sratas' timestamp='1481823889' post='3195498'] Very interesting, but I know there are not many reports of certain cabs failure. My barefaced bb2 can sustain prolonged sub bass abuse, I checked...trust me. and Alex Claber did not recommend a HPF setted too high, lt's say above 30 hz because the driver lowers its excursion and this can impair cooling. At least this is what I understood. Maybe it all depends on the whole design and quality. Waiting for opinions from manufacturers [/quote] [quote name='Marty Forrer' timestamp='1481856681' post='3195785'] I have two Barefaced One10 cabs and have cranked them up to earsplitting volume with and without an FDeck adjustable HPF. My double bass has much more low bass in it than my P bass, hence the A/B with the filter. To tell the truth I noticed negligible difference with or without the filter, regardless of what hz was selected. This tells me that a well thought out and designed cab and driver combination should handle any load. [/quote] A 30Hz filter is sensible, it is too low to make much if any noticeable difference to the sound, as you've observed. A lot of bass amps attenuate the lowest frequencies anyway. If you are running a relatively clean signal path with a double bass you wouldn't expect too many problems. If Alex is recommending that as a frequency I'd imagine he has done all the sums for you. There are other advantages than speaker protection about removing subsonics anyway so if it doesn't affect your sound and you've already splashed out why not use the HPF? If your gear is doing what you want reliably year after year then you've clearly made a whole host of sensible decisions, matching your speakers to the right amp and your particular needs. Most people get there but there are a few casualties on the way. As ever the weakest link in the chain is usually the fleshy organic bit pulling on the strings. I've probably a slightly distorted view because I inhabit the technical bits of the forum mainly offering help in the repairs section to people who's speakers have blown. It usually comes down to 'oh no you didn't really do that, did you'. I'm hoping this thread will reduce the casualties.

[quote name='Marty Forrer' timestamp='1481855735' post='3195782'] One thing that needs stating. There is a big difference between a clean signal and a dirty signal. Most speakers will handle a pure signal many times their rating, but not if the signal is dirty. I went to a Peavey clinic once where 30,000 watts of power amps were cranked full on into a 500 watt speaker with a pure signal running, and it was fine. As soon as some dirt was introduced the speaker started farting and our ears started hurting. I have run my GK MB800 (500w at 8ohms) into my Barefaced One10 cab (200w) no problem, but I run the cleanest signal I can get. [/quote] I don't believe it. That equates to 60A into an 8 ohm load, far too much to be carried by the thin copper wires in a speaker for more than a few miliseconds. you'd not find a mains supply capable of producing that power in most buildings. I've just run a check on a cab with a Peavey Black Widow and the sound levels would reach 150dB, that would have damaged the hearing of anyone within 10m of the speaker. Unless you've misremembered the figures some salesman was telling porkies. If the figure is 3,000W then there is nothing remarkable. A few seconds at that power wouldn't heat the coil enough to damage it and if the pure tone was above 200Hz the speaker wouldn't exceed it's maximum excursion. It would still be enough to damage peoples hearing without some sort of ear protection and would be impressively loud. Dramatic but proving nothing.

Everything decays eventually but speakers are fairly resilient. the biggest problem is likely to be damp. Small amounts of moisture will make the paper cone swell over time and eventually may cause it to distort. Larger amounts of damp may allow fungi to flourish. make sure you store it somewhere dry and if you have open ports in the cab block them, I've found mice in one cab I stored in a garage once I heard them moving when I set up and they ran out at a gig when we started playing

Last bit of advice, choose an amp on the way it sounds not the spec, that's a nice amp you have so only upgrade when you are sue what you have is better. Good luck, it's fun looking.

The first two options are both good, really follow Bills advice on bridging and don't. power wise I don't think you'd find any difference between one per channel and two. 312.5W and 350W aren't going to be noticeably different and frankly it is only 625W into 4ohms because the power supply limits your amp to 625W. I'd run one speaker per channel that gives you the chance to balance the outputs, If a channel went down you'd still have sound and you've reduced the current going through your output stage meaning that amp will run a little cooler.

[quote name='Bill Fitzmaurice' timestamp='1481819614' post='3195449'] Most amps have HP filtering built in. If yours doesn't it will be obvious by excessive thump noise, which is cured with a rumble filter. [url="http://www.gollihurmusic.com/faq/38-HIGH_PASS_FILTERS_GETTING_RID_OF_THE_MUD_AND_RUMBLE.html"]http://www.gollihurm...AND_RUMBLE.html[/url] Ported cabs are no more prone to damage than sealed. If anything you're more likely to over-power a sealed cab, as they have less sensitivity in the lows than ported. Ported cabs also have minimum driver excursion at Fb, where the port is doing all the work. Finally, xmax is not where voice coil damage occurs. That would be xlim. +1. If this was an issue reports of blown drivers would be rampant. [/quote] I'm writing this in response to a handful of people who don't know all you do who have blown drivers. No it isn't an epidemic but it happens regularly to folk on these pages and it is preventable. I'm thinking that one preventable failure is one too many and provoking some debate will help in understanding. I've kept the technical side down to a minimum here but speaker breakdown is complex, well a little anyway. The problem is not always overheating or always Xlim (the mechanical limits to excursion for those who don't do the maths) some of the cases I've looked into look like the result of thermal runaway where the coil is leaving the magnetic gap for significant periods meaning the temperature rises are greater than they would be using AES testing procedures. I've also suspected thermal compression is an issue when a speaker fails. the temperature of the coil rises and the sensitivity of the speaker falls ( I know you've spoken about this in past posts Bill, this is aimed at the interested onlooker) the response in the middle of a gig is to increase the power to the speaker and sometimes to boost the bass.

OK I've reserved this for answers/responses to anything you post up, I wanted to keep the original post shortish

Nowadays it is rare to see any bass cab around that isn't ported, but they all have a basic flaw which isn't widely advertised. If you don't know about it then you could end up with a large repair bill. Ported cabs for bass are generally tuned to 40, 50 or 60Hz , or somewhere in between. the way they work is simple. They are tuned to the frequency where the speaker starts to cut out as it's impedance rises. As the speaker cuts out it's output is replaced by the output from the port giving you very roughly a 3dB boost over the lowest octave. BUT you don't get something for nothing and the cost is what happens below 40Hz (or 50,60 or whatever, depending upon the make and model you use) . Below the resonance of the port the port just becomes a big hole in the cab. Down to that frequency the air acts like a weight and damper on the cone, suddenly that is all removed and the cone is free to move with little resistance. as a result any signal below 40Hz is likely to make the cone move way beyond the limits the speaker is designed for, even with just a few watts going through the speaker. With the coil outside of the magnet it rapidly heats up and it may even start drumming on the back of the magnet, either way complete failure won't be far away. Don't believe me? Try going to the Eminence website http://www.eminence.com/pdf/Beta_12A-2_cab.pdf and have a look at the designs they have for the Beta 12" speaker which is a 250W speaker. Have a look at the design for the large bass cab, they recommend only 75W into their 250W speaker and even so the graph shows the cone moving beyond its 4mm limit at 40Hz. this is a speaker widely used in Eminence equipped bass cabs.

Right, so little difference to my experience then. Thanks.