Newbe - 2225H/2425H/2404H

[HenryW]

I have collected parts for newest speaker project and have used this forum (from afar) to help me decide what I want to do.

The components are 2225H (a 2205 reconed by JBL as a 2225 - basically an alnico, lower power tolerance 2225H), a 2425H and a 2404H. I will be experimenting with a few lens to see where I go with the 2425 (my first, which is not promising as a model, will be a 2345 I was able to pick up).

The intent is to build to a standard (hopefully attractive wood grained) JBL Bass Reflex enclosure for the 2225. I would then put a cabinet and baffle on top of the bass box (much like a LaScala, Belle, Klipschorn design) to house the 2425 and lens and the 2404. In an asthetics consideration I may be using a wood lens (attempting to see what Bruce Edgar suggests) with the 2425. The first thoughts were for crossovers at 800hz and above 5.5khz or there abouts (the horn used will be a big issue for the lower Xover). The housing for the horns would be accessable for crossover work.

Questions:
1. - Are there any standard JBL passive Xovers that would play nicely here? I have seen where the 3110 would be ok for the lower Xover (assuming I can make the appropriate changes for the impedence difference of the drivers). I do anticipate having to build the boxes and measure before getting to where I need for the Xovers, but would be helpful to have a solid starting point.

2. - Does anyone have some lens suggestions?

3. - What are the flaws in my initial thinking? A for instance - the low freq crossover may be unrealistic.

I do want to keep this based on two assumptions - this is the component speakers I want to use and I want to have passive crossovers.

Thanks in advance and thanks for the information I have already gleaned from lurking on the forum.

[jbl]

Hi HenryW,
Go with the 3110A c/o. This is the system I have been using since 1985. Like yours, it consists of the 2225H, 2425J, 2370, 3110A in a 4507 5ft3 cabinet. Sounds great! This is the system JBL specified for these drivers. If possible, get the 3110A opposed to the 3110. The only concern I have would be the impedence of your modified 2205. Check the DCR first. The 3110 had a strange impedance rating for the low frequency section. The 3110A specifies 8 ohms for the woofer and 16 ohms for the HF.

Ron

[Alex Lancaster]

Hi:

Trade Your 2225´s for 2235H´s, the latter are less efficient but put out more LF.

Use a 3110 or 3110A xover they will work great.

I would use a 2312/2308 horn lens.

Put a 1 micro F 100V non polar cap in series with the 2404, connect it in parallel with the 2425; You might add a 16 ohm 50W L-pad either in series or across the 2404 before the cap, try both ways, I use them in series.

I like 170 liter boxes, made out of 19mm (3/4") material, braced with 1 3/4" sq. pine, with a 57mm round port, no tube; some people will like a larger port and a tube, but I do hot hear port noise with the plain hole.

You will end up with a modernized L300/4333 variant.

Hope it works for You.

Alex.

[4313B]

3110 schematic is here:

http://www.jblproservice.com/pdf/Network%20Schematics/3110%20Network.pdf

3110A schematic is here:

Both are basically looking for a 10 ohm load at "crossover".

[HenryW]

JBL - I like that you give the concept an experienced thumbs up. I will be checking impedence both before and after speaker is put in the box.

Alex - Unfortunately being a bit new to JBL components (I can quote scripture and verse on the Klipsch heritage stuff) the 2312/2308 are new to me. They aren't on JBLPros vintage page (as far as I can tell). Can you point me to some information on these lens?

I think I get your cap introduction, but I'll probably have to figure a model before I can ask questions - the only thing that comes directly in mind is that you have suggested one alternative that would put an L-Pad behind an L-Pad and wondered if that would cause any thing quirky in setting up the loudspeaker.

Giskard - thanks. I believe I ran across this on a nomadic internet day once before. From everything I can lay my hands on I am led to believe that 10 ohms is just fine and that either Xover would work well with my woofs.

As to getting the real low freqs - yeah I am planning on tuning to 40hz - the projection shows a tad decreasing response spl that I may need to address, but I have grown fond of a good subwoofer to take the stuff generally below 80hz (therefore the one octave tuning of 40hz). The enhancement to music with a well blended sub is the cat's meow for me. However - tuned to 40hz is a splendid standalone as well.

Thanks again all.

[Alex Lancaster]

Henry:

The 2312's are the 11 1/2" long exponential horns that came on the L300/4333's, the 2308´s are the black plastic slant plates for the 2307/8 and 2311 horns.

My cap and L-Pad suggestion might not be totally correct, but it works; I meant just 1 L-pad, hooked as an inline variable resistor, to the red post of the 2425, then the cap, then to the red post of the 2404, with a direct wire from the black post of the 2425 to the black post of the 2404, You can forget about the L-Pad and just equalize.

Alex.

[4313B]

You might want to check out this thread too:

http://audioheritage.csdco.com/vbulletin/showthread.php?s=&threadid=2162

If you want to be real picky you can change the 13.5 uF capacitor in the conjugate to 11.0 uF for a 2225H and 12.0 uF for a 2235H.

[HenryW]

Alex - now I know what it is. I have seen some for sell, just no specs. Thanks.

Giskard - yep - that thread was reference point for me to use on Xover mods. Thanks

[jbl]

The thread Giskard suggests would be a good place to start. The spec for the 3110's LF varys greatly from on publication to another. Perhaps it would be wise to look at the systems JBL produced using the 3110 (not the 3110A). If i remember correctly, the horn loaded 4662/3 used the 3110. I remember seeing what appeared to be an E-Series woofer. Look at the library for the 4662? It might just list the LF drivers impedance.

JBL