Bill Fitzmaurice

[quote name='Monckyman' post='1200382' date='Apr 15 2011, 05:30 AM']Clipping amps is not recommended by anyone I know in the industry,not P.A amps, not guitar amps,not bass amps. OVERDRIVING them is different, that`s pe-amp stuff, not OUTPUT amp.[/quote]Clipping and over-driving is exactly the same thing. As for clipping power amps, that's precisely what one does with cranked guitar amps, and damaged drivers do not ensue. The Martin document unfortunately is very flawed, as it doesn't distinguish between the potential for damaging tweeters (high frequency devices) with clipped waveforms versus woofers, which are completely and totally immune to damage. This document does make the distinction, though more than a few wags have managed to overlook the specific reference to [i]high frequency components[/i] and pronounce that 'clipping kills drivers', giving rise to the myth of underpowering: [url="http://www.jblpro.com/pub/technote/lowpower.pdf"]http://www.jblpro.com/pub/technote/lowpower.pdf[/url]

[quote name='alexclaber' post='1199073' date='Apr 14 2011, 04:41 AM']Read this: [url="http://barefacedbass.com/technical-information/mythbusters1.htm"]Amp mythbusting![/url] The Wizzy cabs have very low excursion limited power handling so you'll hear the increasing distortion (with clean sounds) well before thermal failure occurs. The risk from slap is causing such high excursion that the speaker doesn't just distort but completely runs out of travel, thus creasing the cone, buckling the voice coil or damaging the suspension. I think that's fairly unlikely to happen with that woofer but to be sure see if EA can tell you the ratio of Xlim to Xmax.[/quote]The xlim to xmax ratio is important, but a high one is by no means a guaranty of driver durability. When pushed past xmax additional power applied doesn't give more output, it just adds more heat. That tends to result in thermal power compression, which actually reduces output, which one may compensate for with more power, which means even more heat, and so on until the voice coil is toasted. And if the xmax is small this can happen well below the actual thermal rating of the coil. This is in fact the usual reason for blown guitar drivers, which have both very small xmax and high xlim to xmax ratios. It still boils down to if it sounds bad turn it down. If it sounds clean chances of damage are very slight.

[quote name='voxpop' post='1198655' date='Apr 13 2011, 03:31 PM']Yes its true, distortion is the thing that blows speakers.[/quote] Distortion doesn't blow speakers. High levels of distortion will be heard, however, if speakers are pushed hard enough where damage could occur. When that happens turn it down.

[quote name='Wooks79' post='1195233' date='Apr 10 2011, 06:49 PM']I was wondering about this and thought I would ask... Why is the ampeg 1x15 (Svt-15e or b-115e) only able to handle 200 watts at 8 ohms?[/quote] Because it's honestly rated. 9 out of 10 drivers with ratings higher than 200 watts can't actually make use of more than half their power rating before running out of excursion, and any more power added gets no additional output. Ampeg rates its drivers closer to the actual power the can make use of, not what it takes to cook the voice coils.

[quote name='Musicman20' post='1191248' date='Apr 6 2011, 06:15 PM']I understand that from an engineers point of view, but a customer? I can guarantee a large amount like ceramic loaded cabs...even if it's psychological. I cannot see them being phased out for a long time now this has happened.[/quote]Ceramic drivers in excess of ten pounds weight will eventually go away because of the price of oil, which determines the price of shipping. The neo situation should have been anticipated, but wasn't until too late. But it will be solved in relatively short order, as many neo deposits exist and the mines are already there, they just have to be re-opened and/or expanded. Investors are already scrambling to buy shares in neo mining, and the price of neo mining stocks has jumped.

[quote name='Musicman20' post='1190924' date='Apr 6 2011, 02:51 PM']I welcome new ceramic cabs.[/quote]The fact of the matter is that no significant R&D has been done with respect to new models of ceramic drivers, as they were in the process of being phased out. No new ones will come along now, as it takes over a year to bring new products to market, and by then the neo crisis will have passed.

[quote name='JTUK' post='1190863' date='Apr 6 2011, 02:20 PM']yes, I recall a that. Personally, I wasn't that bothered that NEO..but did think the AE212 concept had legs at 55lbs. What that will do now with ceramics, I don't know, weightwise....but a single 212 cab in ceramics hasn't been attractive from a weight POV, IMO hmmmm[/quote]Within a year worldwide production of neo will more than double, the Chinese market share (which, BTW, was ceded to them by default) will drop from 97% to less than 60% and all will be well again. And as is usually the case with these things most of the price increase isn't due to lack of supply, it's due to speculation on the futures market. That will probably cause the price of neo to start coming back down within months.

[quote name='DeeBassist' post='1185454' date='Apr 1 2011, 07:33 PM']Hey there, I was just wondering what kind of power I'd be needing for playing gigs going from small pubs, to small stage venues, like, academies and stuff. I was thinking of investing into an Ashdown MAG 810 cab with and Ashdown MAG 300 Head. Would this be enough power to be able to heard in a gig?[/quote] Before considering an 8x10 consider how you'll get it to the gig. 300 watts is plenty, and a pair of 2x10 cabs makes for an easy to transport scalable rig.

[quote name='Lfalex v1.1' post='1185085' date='Apr 1 2011, 01:35 PM']Perhaps they're looking forward to the implementation of an EU concept that would ban combustion-engined vehicles from town centres..[/quote] Which increases demand for hybrid and pure electric vehicles, which increases demand for neo, which results in neo price gouging, which doubles the price of said Orange cabs, leading to their ultimate demise. Just get a big cab, put wheels on it, don roller skates and push it to the gig.

The source of this is rising oil prices. They've resulted in the surge of hybrid autos, which use most of the neo produced, and in response to the demand the supplier has raised the price. Since China enjoys a virtual monopoly they'll get away with it for a bit. But the rising price of neo means that other countries will now start mining neo and manufacturing neo magnets, and both supplies and prices will stabilize. Don't be surprised to see neo mining in Wales.

[quote name='owen' post='1183244' date='Mar 31 2011, 07:55 AM']I felt that pain. I sold it sharpish.[/quote] +1. The appeal of isobarics is smaller size. But with heavy ceramic magnet drivers that size is arrived at via much higher weight. Neo drivers gets us around that, and the size benefit is real, so there is some method to the Orange price madness. You will get the low end output of a much larger cab. If size is a paramount consideration, as in you schlep your gear on the tube or have to carry the entire band in a mini, then the high cost may be worth it to you.

[quote name='Phil Starr' post='1181809' date='Mar 30 2011, 03:00 AM']'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.[/quote]In those respects isobarics operate exactly the same as single driver systems. Some early designers may not have realized how they worked and made erroneous assumptions. Technically what happens with isobaric loading is that with two drivers Vas is halved, and along with it net cabinet volume. But Vd remains the same, as only the area of one cone is exposed to the air, so SPL remains the same as with one driver.

[quote name='Mr. Foxen' post='1181761' date='Mar 29 2011, 07:56 PM']Any idea how the Ampeg thing measured up in practice? Commercial failure/success is more down to garish colour schemes and dubious marketing than anything practical.[/quote] I've only seen them in pictures. The look was OK, the 134 pound weight a wee bit off-putting.

[quote name='Mr. Foxen' post='1181529' date='Mar 29 2011, 05:11 PM']I think in the days when speaker motor power was limited it was a fair advantage, but not so much now.[/quote]It was advantageous 30 years ago and more when driver technology made it necessary for cabs to be very large to reach very low. And then it was applied pretty much to hi-fi woofers and subs, not electric bass cabs, explaining why they weren't employed in them. Ampeg made one, and it was a commercial failure.

[quote name='plankspanker' post='1181464' date='Mar 29 2011, 04:34 PM']...I can't see what the problem is with this but no doubt the purists will throw their hands up in horror.[/quote]Not the ones with a clue. Your setup is preferable to having them both 8 ohms, where the 175 watt rating of the 210 would be the weak link in the chain.

[quote name='phil.i.stein' post='1176590' date='Mar 25 2011, 05:31 PM']i just read that article, i must've missed that issue of bgm. a great way of visualising the 'maths/music' as a concept or relationship. i love it when science boffs like Alex both educate and consolidate your own experience/knowledge at the same time. i would love to see a cool visual (artistic) interpretation of the harmonic spectrum, be it western or otherwise..[/quote] [url="http://www.talkbass.com/forum/f15/bass-frequency-waterfall-plots-what-they-mean-rigs-510749/"]http://www.talkbass.com/forum/f15/bass-fre...an-rigs-510749/[/url]

[quote name='fonzoooroo' post='1159617' date='Mar 12 2011, 12:48 PM']Excellent. Thanks for that reply - It's cleared a lot up![/quote] Somewhat OT, but not completely, I once reviewed a book entitled 'How to Build Speakers' or something of the sort. It wasn't a DIY book, it was a tutorial for potential production managers on how to set up a speaker building factory/assembly line. It was written by a chap who owned a fairly successful speaker company in the 1980s. In the book he admitted that he didn't know anything about acoustical engineering, nor did any of his employees. He got his designs the old fashioned way: he copied them from other companies. Trouble was, he didn't copy JBL or EV or the like, he copied others who apparently didn't know any more than he did. He didn't care how they sounded, he only cared if they looked right, as he knew that's what sold speakers. He was right.

[quote name='voxpop' post='1159356' date='Mar 12 2011, 09:47 AM']Thanks for the info...........[/quote] As for a driver for it, standard box modeling software cannot easily be used. A more sophisticated program like AkAbak or Hornresp is required, unless you can find someone with the requisite gear and expertise to measure the cab impedance. Then you can find out its resonant frequency and use that along with a standard box program to model different drivers in it.

[quote name='voxpop' post='1159019' date='Mar 12 2011, 04:25 AM']I dont think it is a true horn design. Its more of a large vented port the exits the back of the drive unit and vents into a large area at the base of the cab. This kind of cab was very popular in the 1980's....I am sure someone could explain the design and why it went out of fashion.[/quote] Correct. It resembles a rear-loaded folded horn, but it's at best half the required size to function as one. Even a 50 Hz horn is no less than six feet long. Many cabs of this sort were produced in the 60s and 70s by companies who had no trained acoustical engineers on staff. They scaled down real folded horns, like the Jensen Imperial and JBL Keele bins, not realizing that you can't do that with a successful result, and what you end up with is a bass reflex cab with a flared duct. The result was no better than any other bass reflex cab. But as well engineered bass reflex cabs didn't come along until roughly 1975 they did hold their own until then. Interestingly these faux horns were produced by some very well known companies, including Sunn and Music Man, and no, they did not have trained acoustical engineers on staff. Sunn advertised the 200S as a rear loaded folded horn, and it was anything but. Designer Conrad Sundholm admitted that he called it a rear loaded folded horn after seeing the term used, though he had no idea what a rear loaded folded horn actually looked like or how they worked.

[quote name='fonzoooroo' post='1157631' date='Mar 11 2011, 03:28 AM']I recenty got hold of a "COMPACT Sound MKII" 1x15" folded horn cab. What do you think?[/quote]'compact' and '1x15 folded horn' is an oxymoron. Pics and dimensions will reveal if any improvement is possible.

[quote name='chris_b' post='1156230' date='Mar 10 2011, 03:51 AM']OK, that's good to know. I thought it was nearer 12".[/quote] Not hardly. In fact, if the cab is a bit too close to the wall the space between the wall and cab becomes, in effect, part of the cab, and the low end is further extended. That allows you to back off a bit on the low EQ, giving more headroom out of both the amp and speakers. In theory the best port location is down-firing, the cab on feet of specific height. It's possible to make the space between the cab and floor act as an extension of the cab, allowing the cab to be made smaller. But that removes the option of tilting the cab back to better hear the mids.

[quote name='chris_b' post='1155996' date='Mar 9 2011, 05:31 PM']Rear ports can be a problem on small stages. If there isn't enough room to leave a large enough gap behind the cabs your sound will suffer.[/quote]The required gap tends to be no more than two inches, so I wouldn't base a buy on that fact.

[quote name='chrismuzz' post='1155872' date='Mar 9 2011, 04:25 PM']I've been toying with the idea of adding another cab ontop of my Markbass STD 104 HF, possibly the rear ported 104.. but I've heard it's not advised to combine front and rear ports. Any thoughts?[/quote]Port location doesn't matter unless the two ports in question are a half-wavelength apart. The shortest wavelength radiated by a port is in the vicinity of fifteen feet long, the rest of the math I'll leave to you.

[quote name='Phil Starr' post='1150718' date='Mar 5 2011, 11:56 AM']firstly I don't believe this to be a universal truth, I am sure a lot of valve amps work perfectly happily with a lot of ported speakers. If there is a grain of truth in this I would suspect the interaction between the amp and speaker at low frequencies.[/quote] This impedance chart shows a vented low Qts ten loaded cab, the red trace, versus a sealed high Qts ten loaded cab, the green trace. Both are 8 ohm rated cabs. Believe what you will, but the red trace is a very unhealthy load for a valve amp, and cabs of this sort are well known to blow valves and output transformers. That's not to say that all valve amps and low Qts vented cabs don't get along, but when's the last time you saw a manufacturer post an impedance chart?

'Expert Village'? Expert in what? Plumbing? Certainly not sound.