Bill Fitzmaurice

[quote name='MoJ' post='13104' date='Jun 6 2007, 11:13 AM']Ive just looked at the online manual for a particular power amp (Peavey PV2600) and it says that unless in bridge mode, the speakons connections are arranged 1+ and 2+ for the outs, and 1- and 2- are the grounds. Is this still what you were getting at? Thanks Andy[/quote] That's normal for a stereo amp, where you'd have separate cables to separate speakers. To run a single cable to a bi-amped speaker you'd make up a dedicated cord with two plugs at the amp end. [quote]but as I understand low B on bass guitars is someting like 30 Hz. Is there someting Im missing? I gather that the human ear doesnt always need the fundamental to know the note, but surely having the fundamental and being able to reproduce it clearly is a good thing? I know that there must be something Im missing.[/quote] You wouldn't want a cab that runs flat to 30 Hz. The bulk of sonic content, and power demand, for the lower notes lies in their 2nd and 3rd harmonics, 60-100 Hz. Fundamentals only exceed the harmonics in strength once the string length is at least 1/4 wavelength. With a 34" scale bass that's from just about 100 Hz.

[quote name='MoJ' post='12865' date='Jun 6 2007, 04:26 AM']Good to know Bill. Of course buying seperates opens the options up some what. Does the O15 give a pretty natural sound bi-amped, if its all in one cab and with 3 drivers?[/quote] As I noted above, the main reason why bi-amping generally doesn't work well when using two commercial cabs is that those cabs aren't optimized for narrow bandwidth operation. It's a very different story when using two cabs that are bandwidth restricted, or a single cab that has multiple drivers that are bandwidth restricted.

[quote name='MoJ' post='12780' date='Jun 5 2007, 07:18 PM']So Im guessing Bill, that with your designs (if only the O15), bi-amping (of sorts) is something you feel is a viable option for bass guitar? Andy[/quote] Definetely. I don't make a big deal about it because bi-amping bass heads are so rare, but nearly all of my designs are bi-amp friendly.

[quote name='MoJ' post='12736' date='Jun 5 2007, 06:03 PM']Well,this at least tells me that its possible to do with your designs Bill. On the O15, I would assume then that 2 speakon connectors would be put on the back of the cab, and thus connected to the different speakers internally? And the HF horn,would that be connected to the same speakon as the mid driver?[/quote] The usual method employs a 4 pole speakon, with poles 1+ 1- for lows, 2+ 2- for highs, a single cable/jack. For electric bass a dynamic tweeter is often too sensitive, so an option is a pair of piezo tweets instead. This lowers driver cost considerably, and eliminates the need for any passive crossover at all in a bi-amp rig, as the mid and tweeters can be simply parallel wired.

[quote name='MoJ' post='12657' date='Jun 5 2007, 02:58 PM']If its any help Bill, I play 4 string tuned down to low B so I was swinging toward the omni 15 for its lf (correct abbreviation?) and I know that that has internal 3 way crossover in it for the differing speakers. Would a Titan and Omni 10 bi-amped be feasible?[/quote] The O15 can easily be bi-amped, and doing so eliminates a lot of costly and from what I understand hard to find in the UK crossover components. T39 and O10 can go either way as well, and again, bi-amping would save a lot on the crossover parts. I'd only go with an O10.5 with a T39, two tens aren't necessary.

[quote name='MoJ' post='12132' date='Jun 4 2007, 05:44 PM']Does it make a difference Id be using say a 2 x10 and 1 x 15 of commercial cabs? Thanks Andy[/quote] All the difference in the world. Bi-amping (or tri or quad for that matter) is de reguer in the upper end PA genre, where speakers are designed to work with high efficiency, in terms of both SPL and pack space, over a relatively small bandwidth, with no overlapping coverage. That's pretty much the opposite of how most bass cabs are designed, so the advantage of bi-amping with typcal electric bass cabs is greatly reduced.

[quote name='pete.young' post='12164' date='Jun 4 2007, 06:10 PM']So in order to get the optimum bass response, you need a cabinet volume equivalent to the VAS ? It can't be that simple, surely.[/quote] It's not, and stop calling me Shirley. For instance, a Beta 10 with a Vas of 82l works best in a 156l Vb. But 'best' is to a 38Hz f3, which is far lower than electric bass requires. A perfectly adequate 55 Hz f3 can be obtained with only 60l. The bad news is that most manufacturers will use the Beta 10, or the equivalent thereof, in only 30l, so not only is f3 up above 60 Hz but there's also a response hump around 140Hz that results in a boomy tone.

The Basslite Vas is very large and makes the driver one of the least desireable of the Eminence neo line. The Deltalite II 2515 and Kappalite 3015 are far superior.

[quote name='OldGit' post='10987' date='Jun 2 2007, 07:11 AM']So I'm going to email Marco and ask him directly - hey why not.[/quote] It is a fault, one that wouldn't get past FCC regulations this side of the pond, I'm sure you've got a bevy of similar bureaucrats on your side who'd be similarly upset.

[quote name='dave_bass5' post='11013' date='Jun 2 2007, 08:43 AM']Thanks guys yeah, the matt idea is a good one. ill try and track some down.[/quote] Try sellers of power tools. There are mats made to hold wood stationary atop a bench whilst being sanded or routed.

[quote name='dood' post='10478' date='Jun 1 2007, 07:45 AM']I've not heard any stories of the Behri' cabs 'blowing up' or anything.[/quote] I have, many times. Behringer electronics tend to be quite good, but they cut corners on everything mechanical, which includes switches, jacks, pots, and drivers.

[quote name='BOD2' post='7039' date='May 26 2007, 05:56 AM']Can you connect both to the same wall socket to see if this eliminates the problem first ?[/quote] Even then the ground loop may persist, as there will still be two ground paths connecting the devices. Transformer isolation is the best bet for a cure.