Bill Fitzmaurice

[quote name='Jamesemt' timestamp='1320240654' post='1424150'] I've currently got a Shuttle 3 10 with an ampeg mini SVT as an extension cab. That's 300w. [/quote]Get another Mini, stack them vertically. It's not about watts, it's about displacement and sensitivity. Two Minis is a pretty formidable rig, they just won't go real low due to the small size.

[quote name='pbaleiras' timestamp='1320321114' post='1425226'] Ok.... So what do you suggest?!? not forget that the orange has 500Wrms, And i Think should not link a cabinet with less power...am i right?!? [/quote] The power rating means almost nothing. What limits output is driver displacement; see the Barefaced site for an explanation of what displacement is. While an isobaric has the power rating of two drivers it has the displacement of only one, in this case no more than 300cc.

[quote name='citymariner' timestamp='1319972988' post='1420605'] I've just noticed on the 'What's in your rack thread' that someone has mentioned NOT to use a surge protector before the amp as it limits current drain. [/quote]It does not. A so-called 'power conditioner' can, and that's why AFAIK not one manufacturer recommends them, while many recommend against their use. But what 'power conditioner' means has been corrupted; most devices with that label today are actually just surge protected and possibly noise filtered power strips. Price is the clue, and if it costs more than 30 quid or so you don't need it. For that amount or less it's a power strip and won't bother your amp if rated for adequate current draw.

[quote name='Mr. Foxen' timestamp='1319988050' post='1420866'] Has anyone actually tried putting beefier caps into a SS amp, or is there more to it than that? [/quote] Much more. With a standard power supply too much capacitance can lead to a blown transformer, as the initial current rush on power up is determined by capacity. Enough capacitance can appear as a dead short to the transformer until they charge a bit. I'm not terribly familiar with switching supplies, but I suspect the same is true of them.

[quote name='JohnFitzgerald' timestamp='1319968072' post='1420519'] Is one watt the same as another watt ? I know there's more to it than that, but what are your findings ? [/quote] A watt is a watt. Reserve current capacity and headroom is something else entirely. Old 'big iron' amps have high capacity power supplies, most Class D use switching supplies that don't have a lot of storage capacity. There's still much to be said for those fat bottom girls. Of course there arises the question of when is a watt not a watt, and that involves marketing trickery, if not downright deception.

[quote name='bass_by_name' timestamp='1319631490' post='1416608'] I have often wondered about this. Lots of cabs have name badges covering the ports and/or drivers. [/quote] Badges should not cover ports, they will upset the tuning of the cab. I wouldn't cover drivers with them either, though it's less problematic than ports.

[quote name='alexclaber' timestamp='1319203119' post='1411247'] Regarding the thermal thing Bill, one would hope that if a cab is rated at 250W its woofers have endured the usual 1000W peak 250W average AES test for two hours. Surely it would have to be a really crazily loud and long non-stop gig for the RH450 to exceed those thermal challenges? [/quote] That test, as well as EIA 426a, is done with pink noise. The power density with a heavily compressed musical tone is far more stressful. I give builders maximum voltage specs for subwoofer cab/driver combinations, so that they may limit to that voltage to prevent going past xmax, not so much as to prevent mechanical damage but as to prevent long term heat build up. Eminence went through a nightmare situation with the LAB 12 driver and LabHorn, as telltale distortion when pushed beyond xmax couldn't be heard. Drivers dropped by the dozen, and almost all of them died from long term overheating even though they were seldom pushed past Pe. The problem was compounded by a driver chamber that was too small for adequate driver cooling, which was addressed with an aluminum chamber cover that doubled as a heat sink.

[quote name='alexclaber' timestamp='1319197712' post='1411121'] To address the specific problem, the real power output of the RH450 is ~130W into 8 ohms. The RS210 can handle 250W thermally so you can't overheat it. The woofers in the RS210 have small magnets (hence the low-ish weight for a ferrite thick-walled cab) and their sensitivity isn't that low so their maximum linear excursion must be low, thus I'd guess that the cab can handle somewhere around 100W before distortion/compression increases rapidly due to over-excursion (passing the mechanical limit) and you start to approach the failure point. As the RH450 only produces 130W into this load you're not going to be able to push the cab so hard that you reach the mechanical failure point (although you may hear some harmless distortion) so crank it to your heart's desires without fear! [/quote]I wouldn't be so sure. That amp seems to have a very high compression ratio, the source of the magic 'TC watts', so the power density will be higher than the actual voltage swing capacity would indicate. Short term that's not a problem, but between that and the heat retention of ferrite drivers long term heat build up could be a problem. Far more drivers suffer toasted coils from long term heat build up than short term overpowering. IMO if the OP has to consistently push the amp hard to get adequate output he could be looking at shortened driver lifespan, perhaps drastically shortened, so the higher sensitivity of adding a second cab would be in order.

[quote name='charic' timestamp='1319119073' post='1410160'] How is a power rating moot when the question at hand is can I turn my amp to full without breaking the cab? [/quote] I already told you. Go to the Barefaced site and read why displacement, not thermal power ratings, is what's pertinent.

[quote name='charic' timestamp='1318348882' post='1400988'] It says it'll handle up to 400 watts [/quote]Power ratings are moot. What matters is displacement. AFAIK only Barefaced reveals the displacement of their cabs. It's worth a look at Alex's site to learn what displacement is, why it matters, and ponder why every manufacturer doesn't provide it.

Chances are you'll have no warranty. Most manufacturers require that warranty claims be handled by the selling dealer, and even if not still a proof of purchase is required, one from your own country.

http://en.utrace.de/ Use this to trace the source ISP of email.

If it's not just a fuse or bad cable there's nothing you can do to fix it anyway. Check those and if no luck get it into the shop.

[quote name='Nodd' post='1371926' date='Sep 13 2011, 10:03 AM']Thank you Bill, amazingly they do work...for quite a while, advice gratefully received. Stevie, I will have a look at the Fane, need to check overall depth, thank you. All other comments gratefully received. Nodd[/quote]That Fane will give no better a result than the Eminence. They may not be twins, but they are very close cousins. If you're looking for a significant improvement you'd need an Fs in the vicinity of 80Hz or lower, and xmax of at least 4mm. That gets you mainly into the realm of hi-fi drivers, and then you sacrifice sensitivity. There may be some pricey drivers that are better, but there's the rub, they would be pricey.

[quote name='subdude' post='1370067' date='Sep 12 2011, 02:39 AM']i have a pre amp with 1/4" jack line out and an output impedande of 680 ohm that i want to connect to a power amp with XLR input and an input impedance of 20Kohms. do i need a DI box or can a simple adapter be used? thanks[/quote][url="http://www.rane.com/note110.html"]http://www.rane.com/note110.html[/url]

[quote name='fatback' post='1371580' date='Sep 13 2011, 06:03 AM']- is a bass sound omnidirectional from the cab when you're up close, like within 5 feet?[/quote]It's omnidirectional below roughly 200Hz at any distance.

The Alphalite 6 and Alpha 6 operate almost identically. You'd only save 4 pounds using two of them. Neither is capable of useful output below 100Hz, which would explain why you're blowing them.

[quote name='markstuk' post='1370764' date='Sep 12 2011, 12:07 PM']Have you thought about using a lower/angled amp stand? But I suspect what Bill says is the core point - the quieter you are the less feedback you're going to get...[/quote]Feedback is caused by the body resonating in concert with the cab output. Reduce the output and you reduce the feedback. Increase the output and you increase the feedback. Want to get rid of the feedback without reducing the level? Get a solid body.

[quote name='fatback' post='1370248' date='Sep 12 2011, 06:36 AM']I think it cures the feedback just because the cab is not so near the body of the bass rather than because of lost frequencies.[/quote]The distance would not make any difference. It's the notch filtering that accounts for it.

[quote name='fatback' post='1369701' date='Sep 11 2011, 02:09 PM']I've been raising my Midget to chest height by putting it on a keyboard stand. The idea is to stop my upright feeding back, and that's working a treat. However, I seem to be losing a significant amount of volume.[/quote] If the volume you're losing is at the frequencies where feedback occurs it's moot, because if you don't lose the volume you don't lose the feedback. An exact figure is difficult to arrive at, as there are a number of variables. To vastly oversimplify you'll lose about 6dB, centered at the frequency where 1/4 wavelength is equal to the distance between the cab and the floor.

[quote name='CraigPlaysBass' post='1368425' date='Sep 10 2011, 06:40 AM']Good shout guys, ME3008s they are! Spoke to the seller yesterday, he informed me that 3 of them had gone open-circuit and that I could have them all for free if I picked them up. So I did, they were screwed into massive 2x12 scoop bass bins, and had obviously seen some heavy usage. Will check them all today and see if they're repairable at all, if not, I have one that works... Any one got any good ideas for what to use it for? If it's so terrible for bass? [/quote] Between the short xmax and low Qts all it's really suited for is guitar.

[quote name='CraigPlaysBass' post='1367267' date='Sep 9 2011, 03:10 AM']Maybe rebadged was the wrong word, the model evolved into, may be a better one. I'm not normally one to blindly trust what a google search comes up with, but that's the best I could come up with.[/quote] The Delta 12 has a 56oz magnet. Those in question appear to have at the least 80oz, if not 109oz; see the picture of the Kappa 12 on the Eminence website. In this case seeing is believing, and I firmly believe these are not Delta 12s.

[quote name='Linus27' post='1367336' date='Sep 9 2011, 04:38 AM']Should I connect one speakon connection from the back of the amp into one speaker and the second spearkon connection on the back of the amp to the other speaker or one speakon connection from the amp head into one speaker and the from the back of that speaker, a speaker lead into the second speaker? Never really known which is the best way to do it or if it makes any difference.[/quote]Electrically both are parallel circuits, but with two cables to the amp each cab has a separate current pathway. With daisy chaining the current for both cabs must pass through the single cable attached to the amp. With cables of adequate gauge there's no problem with daisy chaining, but if your cables are questionable separate feeds is the safer method. [quote]Apparanly the shorter the cable, the better the sound quality, so daisy chaining would allow shorter cables.[/quote]True with 50 foot cables on PA, not a concern with six foot cables.

[quote name='CraigPlaysBass' post='1367079' date='Sep 8 2011, 05:12 PM']From what I've read, in a few places now, the EM12-2008s were rebadged as the Delta12s, so I will use their specs to build my cab, and see what happens![/quote]Look at the picture of the Delta 12 on the Eminence website. Clearly they're not the same as what you have. Before cutting any wood I'd find someone who has the gear to test the driver T/S specs.

[quote name='CraigPlaysBass' post='1366541' date='Sep 8 2011, 10:50 AM']The seller has just informed me, they are Eminence ME12s and are 300W and 8 ohms. I assume they are the Me12-2008 speakers, which were rebranded as the Delta 12s. There seems to be a few arguments online as to whether they are suitable for electric bass or not. At £25 a driver, however, I'm thinking 'Why Not'.[/quote] They appear to have a much larger magnet than the D12. Rumor has it that Eminence made drivers that look very much like this for Mesa, which Mesa called the Black Shadow, basically a stamped frame EVM12L copy. I had one 25 years ago, and the look was similar, especially the magnet size. It was a very good guitar driver, but not so much for bass, with too short an excursion.