2405H Question

[sourceoneaudio]

I see this driver is used in many different JBL arrays. I have a question on it's power handling. In the Everest DD55000 the system recommended power is 250 watts yet this driver is only rated at Continuous Program Power :40 Watts above 6kHz. ???
http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&ih=009&sspagename=STRK%3AMEWN%3AIT&viewitem=&item=190080890888&rd=1&rd=1 (http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&ih=009&sspagename=STRK%3AMEWN%3AIT&viewitem=&item=190080890888&rd=1&rd=1)
I won this one on e-bay and I'm thinking of re-configuring my center channel and I want to use this as a super tweeter 10k and up 18db per octave cut off. What are the power limitations going to be? I'm going to be running roughly 400 plus into it Adcom Power, GFA-5802. Will it turn into dust??????

J/S-S1A:D

[johnaec]

Two things about drivers like the 2405H. First, the range they operate in, (usually 6K and up), has very little sonic energy to begin with, (for a given frequency, doubling it requires half the power for the same output - that's the essence of pink noise), and second - that driver is so efficient that if you played it anywhere near it's max output at audible frequencies you'd surely be driven out of the room!

I don't think you'll have any problems at all.

John

[louped garouv]

http://www.lansingheritage.org/images/jbl/specs/pro-comp/2405/page2.jpg

this 2405?

I am hoping that you will have passive networks in there?
and the 400 watts is the amount of amp output into the cabinet, if driven fully....

I run bullets (2402?) with 18db butterworths above @ 7000Hz with a Crown D-75... plenty of power for the drivers....

they don't need much IMHO

[Zilch]

Look at the specs.

ONE watt will drive you out of the room....

[sourceoneaudio]

This driver, and yes I will be using a passive network with mylar caps. Also do you think it will be to bright? L-Pad for toning down????

ULTRA HIGH DRIVER
2405H
SPECIFICATIONS
Impedance: 8 Ohms
Frequency Response : 6.5Hz - 21.5kHz
Continuous Program Power :40 Watts above 6kHz
Dispersion 90° x 25° @ 16kHz
Minimum Cut-off Frequency : 7k Hz or higher
Sensitivity (SPL) : 105dB
Voice Coil Diameter : 1.75" / 44mm
Voice Coil Material : Edgewound Aluminum Ribbon
Diaphragm Material Aluminum Alloy Flux Density : 1.75 Tesla
Magnetic Assembly Weight 1.5kg. / 4.125lbs.
Net Weight : 2.3 kg. / 5 lbs.
MOUNTING INFORMATION
Overall Diameter 4.75" / 121 mm
Overall Depth 3.75" / 95mm
Baffle Cutout 3.125" / 79mm

J/S-S1A :D

[scott fitlin]

The 2405 sounds best crossed over at 8K or higher. 18db Butterworth ( 3rd order ) filters are what I like personally.

A 400wpc amp is WAYYY too big for them. The 2405 will be spitty, shrieky, and harsh sounding with such a huge amp. 1 little ol Crown D75 is plenty.

Besides the power, you must also consider the input sensitivity of the amp you use for tweeters, as when you cross over at 8K there isnt enough signal to drive a larger amp with an input sensitivity of we shall say 1.5v or higher satisfactorily. The input sensitivity of the Crown D75 is 1v, and will be much more responsive to the small signal you send into the amp, resulting in not having to push your system, or active xover output level as hard, and will sound good.

FWIW, the Crown D75 is a great match, synergistically, to these JBL tweeters. If you can find a Crown Power Line 2, I like them even better.

[Zilch]

You must match the sensitivity of the 2405 to that of the mid/high driver and whatever network it's running on.

Unless that's 105 dB, you'll likely have to pad it down, yes.

I believe Greg Timbers suggested the ring radiators sound best crossed through a dedicated chip amp:


The ring radiator hates passive networks. A major improvement in the upper range would be to drive the 2405 from its own little amp. You only need 3 or 4 v rms. The 2405 does 110 dB for 2.83v. It is padded way down in the system. There is little real power at those frequencies anyway. You only need to know the voltage output of the amp, power is irrelevant. The 2405 is about 12 ohms and won't draw much current. I would use some little chip amp with a 2ond or 3rd order low level highpass in front of it. Take off the passive network to the ring and just feed it straight. Make sure the amp doesn't make a DC thump on turn on or turn off. That will fatigue the diaphragm. The amp will also have to have really low noise characteristics as any hiss will be really loud directly into the ring. I used to use an old Marantz 1030 integrated amp to run my rings. I could separate out the power amp section and the tweeters always sounded really good.

[scott fitlin]

L-Pad for toning down????

:DYeah, you definitely need the L-Pad to attenuate them.

So, the 400wpc amp drives the entire speaker system? Youll need to pad the tweeter down.

[sourceoneaudio]

Scott,
I'll be using the same drivers that are in my Avitar. I will be building a new enclosure for this new idea.

RF-7 Specifications (Klipsch)

frequency response 32Hz-20kHz ±3dB power handling 250 w max continuous (1000 w peak)sensitivity 102dB @ 2.83 volts/1 meter nominal impedance 8 ohms crossover frequency 2200Hz

Looks like the sensitivity is very close on the drivers, and the power used (left channel of the GFA-5802) will be going to the whole center channel system. One 10, One Tweeter rolled off at 10k 6db per octave, and then the 2405H coming in at 10k 18db per octave. The other 10 in the pic is driven off of the right side of the amp LFE in a seperate enclosure. That driver is out of a Klipsch RSW-10

J/S-S1A :D

[scott fitlin]

You`ll still need the L Pad. These things put out, very efficient. 1 watt, as Zilch said, will make em go, and go loud at that!

Put it another way, I run JBL 2402,s in my place, sixteen of them, only 2 Crown D75, or Power Line 2,s, to drive them. 10 watts to 12.5 watts per tweeter, they are in arrays of four each, and each channel of the amps drives four JBL 2402,s. I also have six 2404,s one on each stack, 1 crown D75 runs them to satisfactory level.

I also have six 2405,s, I was going to use them in place of the 2404,s. Let me tell you, they sounded just as loud as the 2402 bullet with the SAME amount of power as the bullet, and the bullet is rated 5db higher sensitivity ( 2402 = 110db 1w@1m ) ( 2405 = 105db 1w @ 1m ). I was surprised, but the slot sounds as loud as the bullet, but, the slot does go higher, and that is audible.

Through the years, I have experimented with bigger amps, power levels that more closely resemble the tweeters rated power capacity, and each time, I run back to the smaller amps. The JBL tweeters are very efficient.

Once you get it set up, your ears will tell you what to do.

:)

[sourceoneaudio]

Thank you for the advise. I'll post pics as the project progresses should be very interesting, and quite interesting to hear when done.

J/S-S1A :D

[scott fitlin]

I do have one question for you. I`m assuming the OTHER tweeter you mention is the horn in the center of the cabinet?

If so, why a 6db roll off? I tend to think you would want the roll off the same as the tweeters high pass, to avoid phase discrepancies, and too much overlap between the two different drivers.

[sourceoneaudio]

Scott,
Yes I have thought of going that direction for less overlap. The middle driver is the horn it's the high frequency horn 8" square 90°x60° Tractrix Horn in the RF-7.
The 2200hz high pass in the factory system is also an 18db network.
I'm trying to remember from past education building x-overs. That if I run a 12 or 18db low pass after a 18 db high pass does it get wired out of phase for phase correction on the input side? Then wiring the 18db high pass at 10k is that in phase our out on the input side?

Jeff
J/S-S1A :D

[Robh3606]

Hello Jeff

How high do your horns go now?? That 21Khz is real the output drops off like a rock above that. At 10K with the driver spacing just go with what sounds best as the phase will be difficult if not impossible to get right because of the short wavelenghts at those frequencies.

Rob:)

[sourceoneaudio]

Rob,
The only specs I have access to is what is published, as stated in above thread they go to 21.5k. Klipsch does not, and will not divulge any driver parameters it's all top secret.
The reason I'm thinking of adding this driver is I have heard it used as a super tweeter in a center channel application kind of like where I'm heading, and the addition to detail was incredible. I liked it, and I think it would be a nice touch to my system.
Also thank you for the input on my phasing question. I know I'm way up there on the bandwidth so as far as safety goes I also should have no issues with correct phasing? So running all x-overs parallel is ok (high pass and low pass) on the horn and the 2405H?

Jeff
J/S-S1A :D

[scott fitlin]

I would use an 18db roll off for the horn, same as the HP filter for the tweeters. A 6db roll off for that horn will be too much overlap between the horn and tweeter.

[sourceoneaudio]

Thank you Mr. Scott.
When I sent the reply and included the 6db roll off idea I realised that was probably not the smartest thing to do. Probably sound kinda nasty eh'.
Thank you again for the help. I want to get it right the first time since the finisehd product is so heavy. Taking it up and down off the TV is a two person job. The cabinet will either be double layer 3/4" or 1" stock in the upwards of 150lbs. when done. A back breaker at that.

J/S-S1A :D

[Mr. Widget]

...and I'm thinking of re-configuring my center channel and I want to use this as a super tweeter 10k and up 18db per octave cut off. What are the power limitations going to be?You will be fine... definitely use a padding system of some sort, an 8 ohm L-pad would be the simplest. It really doesn't matter what amp you use... the rest of your speaker system will be most affected by the power available from the amp. Build your network with an adjustable pad and enjoy. On the other hand, if you are after SPLs greater than 120 dB then, you'll entering into the danger zone... both for your hearing and for the tweeter's life expectancy.


Widget

[scott fitlin]

Thank you Mr. Scott.
When I sent the reply and included the 6db roll off idea I realised that was probably not the smartest thing to do. Probably sound kinda nasty eh'.
Thank you again for the help.

J/S-S1A :DWell, what happens is that there will be phase difference between a 6db and 18db slope. Then, if the horn doesnt roll off steeply enough where the tweeter comes in, you wind up with too much sound around the crossover region from the horn, and the tweeter doesnt sound as apparent.

[sourceoneaudio]

Well, what happens is that there will be phase difference between a 6db and 18db slope. Then, if the horn doesnt roll off steeply enough where the tweeter comes in, you wind up with too much sound around the crossover region from the horn, and the tweeter doesnt sound as apparent.

Yes, I think that would be most evident, and NASTY :barf: .

Mr. Widget,
Thank you for the tip. I'm not seeking that kind of SPL though I do like it loud. About 1hr is the limit to high levels in the HT room after that the headache sets in from the SPL levels, the system plays very loud and very clean. So I know I'm getting up there in the upper SPL range. One day I will measure it, because I'm curious. With the addition of the 2405H I'm seeking a detail addition to the center channel configuration, like I said in a previous post, I've heard it and really liked it. So I think I'm on the right track. Thanx again for the control tip.

J/S-S1A :D

[Allanvh5150]

Years ago, when I was a sound engineer for live bands, I used a 2402 and 2405 in the same box driven with a 500 watt amplifier. They just sat there and sizzled. The 05 was a beautiful driver, but alas, it has gone. Long live the 2405!