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R Beardsley
10-12-2005, 07:28 PM
I have two 2245H's I want to wire to one amp. Right now I have one powered by a bridged JBL/Urei 6260. Since I have a 6290 dying to be used, it would seem that 1200 watts bridged and the drivers wired together would be better than separate channels @300 watts. Am I correct in thinking that I'm not going to get something for nothing? Should these be wired in parallel?
"Duke" Spinner
10-12-2005, 08:06 PM
H is 8 ohm nominal ..

i don't know how low they actually dip ....

do the Urei's mind a 4 ohm load ..>>

probably not , thier built rugged
scott fitlin
10-12-2005, 08:06 PM
You would wire in parallel for a nominal 4 ohm impedance. Its alot of power in bridge mono, just be careful.
"Duke" Spinner
10-12-2005, 08:07 PM
OOOh ...

you said "Bridged"

lotsa amps don't like 4 ohm, when bridged ...
scott fitlin
10-12-2005, 08:14 PM
You can run the 6290 bridged at 4 ohms. No sweat.

Its a sturdy amp.
speakerdave
10-12-2005, 09:18 PM
You can run the 6290 bridged at 4 ohms. No sweat.

Its a sturdy amp.
JBL does not rate any of that series at 4 ohms bridged. I'm guessing that the distortion figures would not have fallen within the spec they wanted. I'm not sure what that means exactly but I think the way the power ratings go--300 wpc at 8 ohms, 600 wpc at 4 ohms, 1200 watts at 8 ohms bridged--means that the power supply is giving everything in every configuration. I would bridge both amps and put one on each woofer. If you are finding that at the levels you actually play you can hear a difference, then hunt down another 6290. There are three or four on eBay right now, although I advise caution buying used pro power amps on ebay. But I'm betting you will find the arrangement with the two different amps bridged will work well.

David
GordonW
10-12-2005, 10:09 PM
I remember, at least in the later model 6290 literature (I worked at a dealer that sold and rented JBL Pro gear back in that era), that there were 8, 4 and 2 ohm stereo power output ratings (300w, 550w and 750w, respectively, IIRC), and bridged ratings into 8 and 4 ohms (1100 and 1400 watts, respectively, IIRC).

My only concern, is that the 6290 in stereo 8 ohm mode ALREADY meets the rated power of a 2245 (300 watts)... you may not really get any appreciable benefit to bridging the amp. After all, IME, you can already "bottom out" a 2245 on 300 watts, below 30 Hz, even with a vent tuning in the low-20Hz-range. Might be louder in the midbass with a bridged amp, but not much more to be had in the ULF region...

Regards,
Gordon.
scott fitlin
10-12-2005, 10:25 PM
The 6290 can do 4 ohms bridge mono.

That said, I prefer amps run in stereo. We used to run amps in bridge mono, and while they do give somewhat higher power, its safer in stereo, and to my ears, sounds better. In stereo, the amp has, or at least sounds like it has better control of the woofer cone!

And, as Gordon says, it can easily bottom your woofer out!
Zilch
10-12-2005, 11:09 PM
300 Watts per channel in stereo is better. It'll be twice what you presently have running....
speakerdave
10-14-2005, 10:26 AM
The 6290 can do 4 ohms bridge mono.

That said, I prefer amps run in stereo. We used to run amps in bridge mono, and while they do give somewhat higher power, its safer in stereo, and to my ears, sounds better. In stereo, the amp has, or at least sounds like it has better control of the woofer cone!

And, as Gordon says, it can easily bottom your woofer out!

Right, the amp will survive 4 ohms, but will not sound as good as you or JBL wanted it to, so they didn't rate it at 4 ohms bridged.

As for the usefulness of headroom in an amp running the 2245, in the original construction article in Audio Magazine for building the B380 and B460 the authors said that they had used the subwoofers with up to 2000 watts and they only sounded better. Naturally you're supposed to be able to hear distress when it starts happening. Anybody contemplating experimenting with the nuclear option through a subwoofer should wire in high pass filtering.

David
Mr. Widget
10-14-2005, 10:50 AM
300 Watts per channel in stereo is better. It'll be twice what you presently have running....

I agree. Running amps in briged mono is typically not the sonic ideal anyway. The amp will have better control and you'll have better, tighter bass running the amp in stereo. (Feeding it a mono signal, you'll still have mono bass.) The difference in maximum SPL will not be all that great.


Widget
scott fitlin
10-14-2005, 05:56 PM
I agree. Running amps in briged mono is typically not the sonic ideal anyway. The amp will have better control and you'll have better, tighter bass running the amp in stereo. (Feeding it a mono signal, you'll still have mono bass.) The difference in maximum SPL will not be all that great.


WidgetAnd in some cases, you actually get MORE runing the amp in stereo than bridge mono! I dont exactly know why but it is this way!

When we used to run our stuff bridged, the bass had a harder sound to it. When we went to stereo mode, we liked the tone better!

If you DO decide to run the amp bridged, you gotta pay attention when you really pump your system, cause when and if you clip, youll hear about it from the woofers, this I tell you from experience.