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FredEmmerich
03-31-2005, 02:14 PM
If you decide to go with a subwoofer setup, and decide to run a separate amp for the sub, is there any rule of thumb for the power of that amp relative to the amp running the mains? I was wondering if there is a percentage split kind of go-by?

thanks
Fred

Zilch
03-31-2005, 02:38 PM
2X

6230 Mains
6260 Subs

Titanium Dome
03-31-2005, 02:47 PM
Whether by dumb luck or clever planning, the JBL Performance Series PS1400s come with 400W amps that seem to be well-balanced with the 200W/ch that I'm putting into the Performance Series mains, center, and surrounds. So I agree.

Robh3606
03-31-2005, 03:51 PM
Depends on a couple of things. Since you are asking about power in I assume you are building them and using an active crossover. You could also use a plate amp however the slopes may not be steep enough. There is no clear cut power ratio. It is driver and tuning dependent. I would go by the rated power the driver can handle and see in box software what the displacement curve looks like with max power PE. Use this to tailor your amp size. Also consider the effect of where your crossover is. Here's why. I run LE14A's which have a limited x-max compared to more modern woofers. There peak displacement is around 50Hz in the tuning I use them in. I cross them other a 50hz using 24dB L/R slopes so they are 6dB down or 1/4 of PE at crossover where the peak displacement is. They run out of displacement at around 25Hz but I have very aggressive high pass filtering around 20Hz with multiple cascaded filters. Because of the filters and crossover point, over the narrow range they run I have never ran them into audible trouble in my size room. So the bottom line is don't go nut's power wise unless the driver you are using can absorb it without damage in the box you are using.

Rob:)

FredEmmerich
03-31-2005, 05:55 PM
Next question is, I have 250ti and I am hunting a good sub, then to find some amps to drive them. I have a Mac 2100 with 105 per side, but I am not stuck with that. I was going to get a 350/channel amp with just the 250ti to see how it sounded.

I also have some 4425's and my question really applies to them.

Robh3606
03-31-2005, 06:06 PM
How much room do you have??? You could look into the sub that JBL uses under the 6332

http://www.jblpro.com/LSR/PDF/JBL.LSR6312SP.pdf

or build your own. Use a 2235 or a pair for stereo but you need room for the boxes.

Rob:)

Zilch
03-31-2005, 08:18 PM
One forum member has mated 4425's with Citation 7.4 subs successfully.

Use "Search" to look them up. They use LE14H-1 woofers. Easy to build some....

JBLROCKS
03-31-2005, 08:33 PM
Hey Zilch your Avatar is distracting from the discussion ;) :applaud:

dieterj
04-01-2005, 06:07 AM
Next question is, I have 250ti and I am hunting a good sub, then to find some amps to drive them. I have a Mac 2100 with 105 per side, but I am not stuck with that. I was going to get a 350/channel amp with just the 250ti to see how it sounded.
I've also the 250ti, and have the Plan to build 2 Subs in 8cu with 2245h
this Year.
The Amp for them is Crown K1 with 350/ch. :D

Maron Horonzakz
04-01-2005, 06:09 AM
I,m not complaining.;)

Mr. Widget
04-01-2005, 09:25 AM
I think Sister Wendy is much sexier... but that is just me.

Widget

BTW: For info on power needed on Bi-amping, I'd say Rob nailed it. There are many variables.

pmakres1
04-01-2005, 09:49 AM
Next question is, I have 250ti and I am hunting a good sub, then to find some amps to drive them. I have a Mac 2100 with 105 per side, but I am not stuck with that. I was going to get a 350/channel amp with just the 250ti to see how it sounded.

I would suggest the B460 Sub with a quality amp with ample power to drive it. I have L220 mains and B460 sub and it's a great combination. The B460 was developed in part to compliment the L250, the 250ti's predecessor. (see the JBL library, there you will find a brochure that describes the L250 and the B460 in the same brochure. Also there you will find a brochure that describes the B460 and B380 subs. The B460 utilizes the 2245H 18-inch Low frequency driver, in an 8 cubic foot vented enclosure. It produces extremely deep, powerful bass.


I see you are also a MAC fan. I drive my L220's with a McIntosh MC300, and last year I upgraded my sub amp to a McIntosh MC252, running in bridged 500 watt mode, to drive the B460. You will also need the JBL BX63 dividing network that was developed for the B460. You can also use the later BX63A version that includes variable crossover frequency. The standard BX63 begins its rolloff to the sub at 63HZ. In addition, the BX63 has the capability to bridge the inputs of a 2 channel power amp to run the B460. Before I upgraded to the McIntosh MC252, I used this method to run the B460 with a Hafler DH-500 Amplifier.

If you run the B460 with a quality amp with ample power, together with the 250ti's, you will have a stellar combination! :thmbsup: :thmbsup:

Best regards,

Peter

Zilch
04-01-2005, 10:19 AM
I also have some 4425's and my question really applies to them.B460?

http://audioheritage.org/vbulletin/attachment.php?attachmentid=3521

FredEmmerich
04-01-2005, 10:57 AM
A B460 would be great and that is what I want, but finding one is a different story!

Don Mascali
04-01-2005, 11:15 AM
I dunno, two B460s sounds better as in, "Too much is just right".
You need two for room mode control.:applaud:

Zilch
04-01-2005, 11:19 AM
My point being that B460 is gross overkill for 4425's.

http://audioheritage.org/vbulletin/attachment.php?attachmentid=3533

Everybody has a lust for the biggest, baddest subwoofer imaginable.

Look at the experience of those who have actually built or acquired monster subs, related here in the forum. It's FUN to flex the ceiling and crack the stucco?

Well, briefly, perhaps.

A pair of Citation 7.4 equivalents is appropriate for 4425's. Or smaller, even, 5.4's or L212 sub.

A single B380 would be more than sufficient....

Zilch
04-01-2005, 12:05 PM
I think Sister Wendy is much sexier... but that is just me.Not sure I like how she's lookin' at the Biradial Babes, tho.... :p

pmakres1
04-01-2005, 02:20 PM
Next question is, I have 250ti and I am hunting a good sub, then to find some amps to drive them. I have a Mac 2100 with 105 per side, but I am not stuck with that. I was going to get a 350/channel amp with just the 250ti to see how it sounded.

I also have some 4425's and my question really applies to them.

....I do have to admit I sort of read "over" the last sentence without paying too much attention to it, I read it as if your question applied "also" to the 4425's instead of "really applies" to the 4425's. After all, the first paragraph sort of reads as if you were looking for a sub to complement the 250ti's. That said, I do have to agree with Zilch that the B460 is an awful lot of sub for the 4425's, and perhaps the B380 may be the more logical choice.

You have pointed out that the B460 (and the B380 for that matter) are hard to come by these days. I know the feeling-I wanted a B460 for years and years and it wasn't until about 6 months after I started eBaying that I finally found one on eBay. The 380 and the 460 do turn up from time to time on there. They are both great subs and worth the wait if you can find one. I've always been glad that I stuck it out and waited for the sub I really wanted instead of compromising for the sake of having a sub in my system "today".

Good luck in your mission!

Peter

FredEmmerich
04-01-2005, 02:45 PM
I do have 250ti's and 4425's and getting a good sub for both would be cool, although the 4425's need a sub more. I lost out on 2 B380's last week on Ebay....


Fred

pmakres1
04-01-2005, 03:18 PM
I do have 250ti's and 4425's and getting a good sub for both would be cool, although the 4425's need a sub more. I lost out on 2 B380's last week on Ebay....


Fred

...I remember hearing about that auction from someone here on the forum. I did take a look at the listing. I remember it especially because of the unusual nature of it...two B380's. You're lucky to find one these days! Keep trying and good luck..be sure to tell us when you score!

Best regards,

Peter

dieterj
04-02-2005, 01:30 AM
I dunno, two B460s sounds better as in, "Too much is just right".
You need two for room mode control.:applaud:
I will dry this combination this year.
I hope my neighbours're not angry after :D

Zilch
04-02-2005, 01:02 PM
Build 'em. There's no magic here.

http://www.lansingheritage.org/html/jbl/reference/technical/1983-subs.htm