View Full Version : crossover for 2206/2417+2432/2405

03-04-2004, 09:31 PM
I am finally diving into to trying to build my crossovers for my ultimate speaker. I have purchased and will be using a pair of 2245H for sub/low freq, 2206H for midbass, 2417+2432 for upper mid/low treble and a 2405H for my high freq. I have several active crossovers but will probably biamp with a mid/high quality components passive crossover for the upper freqs. Before I reinvent the wheel, could anyone remember any threads with similar designs, or aware of an off the shelf JBL crossover that may be easier to modify then start from scratch. I planned on doing a psuedo 4345 like design and had access to the crossovers for those but the impedances are different and the horn is equalized for the other horn. Also I want to incorporate all the current mods. I have had people crunch the numbers and guide me through the pitfalls on several smaller designs but I could use a referral for someone with JBL experience who could help me do this (possible barterring involved;) ) or would appreciate any input about directions, pitfalls, things to avoid etc. I have been building speakers at different levels of success since I was 8 years old, but I have never had this much invested in building a speaker both money wise and emotionally and want to do it right.

03-05-2004, 01:16 PM
Good for you soundslike fun! What I would do is look at the 4722/4722a schematics and lift the crossover from there. The integration on the 2405 will be hit or miss. You can play around on the compensation of the 2342 with values of R across the driver and cap value changes. Post some pictures and let us know how it goes.


03-09-2004, 03:48 AM
Fellow JBL nuts,

This is a reply to some question from Andreas on some specific topics. The content may be of interest for others so I have taken the liberty to post in the thread.

Also there should be many others on this grand forum with other experiences that could chip in.

I don’t claim to have “the answers” but merely a personal view based upon what my measurements and my ears tell me.

Please add to this thread to improve the chances for a good system for Andreas and the rest of us.

Below is some background:

Questions 1:

Did you build the speakers in your avatar, they look very similar to the kind of speaker I am attempting to build. I would be interested in any info on them, (another thread maybe?). I am considering building a HT pair of speakers with 2245, 2417 with the 2342, a 2405h or 2404h and some as yet unidentified 10 inch midbass (maybe a 2121h)

Answer 1:

Yes it was a project I built some years ago. It is smaller than your ambitions. I sold them last year. They are in a mastering studio as main monitors now. :D

It was a 2234, 2118, 2421 (with a 2425 membrane) /2344 and a 2404 on top.

If you do a 2445 and a 10" mid I would strongly consider a 2426 or possibly a 2447/2451 driver. I don't think the 2417 will be strong enough and may also prove to be the weakest audible link in you setup.

The column-type speakers are rather sensitive to how you place the drivers on the baffle so you will have to build a few test boxes to find a good solution (meaning avoiding diffractions/refractions)

Question 2:

Did you try the slot tweeters before the 2404, what’s your opinion. I have two functional 2405h speakers, and two 2404h that need diaphragms. Did you design and build your own crossover? If you did, suggestions for shortcuts on the design.

As you can see I am just getting going on this and pretty open to suggestions, I even considered 2445J/2380a horns at one point but thought a bit of overkill for the application.

I also have the Revel 1500 subs from Parts express, may use them instead of the 2245, I am not as worried about the low freq, but the design of the crossover is going to be a bear for me.

Answer 2:

Hi Andreas

I think the 2426 would be an excellent choice if you XO at above 1.5k. If you intend to go below I would go with a 1,5" driver. The 2426 won't be able to play as loud and relaxed as the rest of the system. IMHO the 1.5” drivers does sound slightly better when I compare the two side by side in my test rig.

If you do the 2”/1,5" driver setup starting from scratch, I recommend that you stay away from the older drivers. I have played around with some of them and there is an audible improvement starting with the 2446/2450. The design of the older drivers may be is just that, old. :D .

BUT, if you like them, you should keep them. Many do like the older drivers and argue that they sound smoother with the Alu or Phenol membranes. I can see their points and it does have some merit. Only your ears can decide what is best for you. I prefer the newer designs and they also measure better.

In my view the 1,5" drivers 2447/2450SL (coated membrane) and the 2451 are all improvements over the 2" drivers for home use. The frequency curve is smoother and they also go a bit higher with less effort. The cost is that they normally do not play as loud in the low region and have to be XO’d slightly higher than the 2”. Remember that the motor and the membrane are the same in both. The main differences seem to be in the lack of the impedance throat leading in to the horn and also a new generation phase plugs for the 1.5” drivers. There are some good “white papers” on the topic to download at the JBL site.

Today I would hesitate using a 2” driver at home, given a choice of a 1.5” based upon the above and also that most of the horns are physically too big for home use. I will use the 2451 my self. The best choice may even be the 2450SL, which is a 1.5” version of the 2450 with a coated membrane without the reinforcements on the dome and without the impedance throat. The SL membrane does seem to have less tendency of ringing when you go up in frequency at the price of earlier roll off. They are used in the old K2 speakers that were 2-way systems

-But if you, like me, intend to put a tweeter above the driver I would stay 2446/2451 because the ringing won’t be a big problem below 10k and the later fall off is easier to compensate for in the filters. Or get a pair of 2447/2451 without membranes and some 2450SL membranes. They should go straight in. Correct me if I’m wrong here, as I have not used the 2450SL.

Choice of horns is difficult. I guess that you just have to try out what you find sonically acceptable. I will use the 2332 that originally were designed for the last of the big size studio monitors, the JBL DMS-1. They are available as spare parts I belive. Having listened to some different alternatives I find them being a good horn for home use.

It is also very compact which means that you can put the different drivers rather near each other in order to avoid the “ping-pong” effect, which haunts all big monitors at short listening distances often used at home. Unless you would like to use the system like a “hair dryer” I would stay away from the physically big horns. I have yet to hear a big system with a really big mid horn that sounds focused and coherent in the often-short listening distances of a home environment. My old system (in the avatar) suffered the same problem. I had to move at least 5-7 meters away to get a focused sound patters from the different drivers. The speaker cabinet was maybe 55” tall. If your HT is really big, go for it !! :D :D

For a tweeter I used the 2404 in my old construction mainly because it had identical dispersion patterns as the 2344. Together they gave a very nice combination. Today I would say that the 2344 may be a little bit out-dated even though I know that many on the excellent forum thinks highly of it. 2344 is a bi-radial design where most of the newer horns normally are CD designs.

I personally would go for a newer, rather shallow horn. The shallow horn seems to have less coloration of the sound in shorter listening distances (don’t really understand why thought) and you do normally not need the throw length of the deeper horns. You also will have less time alignment problem due to the smaller difference in depth. You can indeed compensate for some of this in your active filters, but not all. At least I can’t get to grips with it. I’m using digital XO’s but I still can’t get rid of all of the timing problems.

Due to the shallow base of the 2451/2332 and the timing correction in the filter I don’t think it is cumbersome for the sound but I’m a little bit in doubt that you could get the same result with a much deeper horn. Remember that in PA use, the distance between the listener and the speakers is long and that makes up for some of the perceived timing difference. And also bear in mind that JBL them selves have not made a Studio monitor with real deep mid horns in recent years.

If this were the case, in which you decide to use a newer horn design I would go the 2405 route. 2405 is IMHO a better tweeter and you will find that you have fewer problems integrating them in the design. It is also less sensitive to placement on the baffle.

I’m very tempted to use the 2405 myself, but since I don’t aim at the sound pressures your will get with your system I will use the 025Ti dome normally found in the Ti10K speaker. It is an Audax unit (Harman owns Audax) and is very flat from 7k to over 25k. I will use it from above 10-12k (not clear yet). My woofers have very low sensitivity so even with two of them in parallel I only get about 93db so I don’t need the high sensitivity of the 2405. If I had them like you do, I would not hesitate one second. :D

Ooops, that was a lot over little.

I will also use the SUB1500 drivers in my system. I think you can go either way. If you do the 2245 you can run it a bit higher XO than with the Sub1500, which puts less strain on the low mid driver. A 10” or even a 8” would probably be just fine. Have you checked out the JBL 208G 8” drivers used in the LSR28. Two or three of them would rock. I would probably stay clear of the 2118 as it in my ears sound a bit harsh.

If you do the SUB1500 I guess that XO would have to be significantly lower meaning dual 8”/10”s or a 12” low mid. 2206 may be a good choice here. I will do dual 8”’s above the SUB1500’s to keep volume and size down. My 8” are really woofer units that will be forced to go up to 1k with compensation. They have really high x-max for an 8” and will be ported around 40Hz. The SUB1500 will kick in at 60Hz.

In your system I would definitely go active XO between the woofer and the mid regardless of which woofer/sub driver you choose. I use 4 way digital XO’s feeding a Crown CTs8200 for the system and I am on the look-out for a cheap used Crown K2 or CTs2000 or CE4000 for the subs. It may be overkill to go active for all elements but one you get the taste for what digital XO’s can do, it is really difficult to turn back….

For my old system we did do our own passive XO’s. I will try to find the crossover drawings and post them here. We have moved around a bit so they are in a box somewhere. :D

Best regards


03-10-2004, 08:54 PM
I have emailed OCS and they can recone my 2121h speakers with original 2121h cone kits. I know there is another thread about interchangeability of kits, but what I need to know is regarding the sound of my 4345 clone and which kit would be best. The frames are reconstituted 2121H frames, I will probably end up with 2245/21XX/2425J+2307+2308/2405h. Would the 2122 kit be a better choice then the 2121, would it be better to just buy some NOS 2123s. I am open to suggestions. Sound is my primary concern but I do like the look of the original 2121 :cool: .

03-10-2004, 09:12 PM
If I remember correctly the 2122 was an inproved 2121 and that inverted dustcap had break up issues when driven hard. If it were me I would go for the new and improved providing the frames allow for it. As far as a 4345 clone the 2122 is the choice. You won't have network issues as the 2121 and 2122 are not interchangeable. The 2123 is a great driver. If you where running an all active system that would be my choice as it is smoother than either the 2121 or 2122. If you are going to go passive, 4345 network, stick with the 2122.