Here some picture of the JBL 4344s I recently finished.I’d like to start by thanking all the DIY’s who post in this forum as without your contributions my project would not have been possible!Components 2235, 2123, 2426H, 2405, DIY charged couple cross-overs.I used the plans from Ayaboh – fabulous saved many hours/days/weeks of planning. I did not really deviate from them.Wood used 1” MDF for all panels 3/4 in Baltic birch for the baffle, 5/8 Baltic birch for the 2123 dog box and panel bracing, walnut veneer and trim. Stainless Steel for the LPAD focial, 2405 mounting plate and 2308 lens. White birch veneer stained black for the baffle. Everyone like tools, here’s the machine I used for the project members from down under may recognize it.
I bought it back in the late 80’s for my last speaker project. It’s as accurate as any real saw/router table and folds down and can be put away for those of us that can’t dedicate space to a permanent workshop. Drawback is that no third party jigs will fit; you have to make your own. The extension table is wonderful as ripping a 4x8 is easy. Well it was when I was younger for this project I went to my local RONA and had all the pieces cut close to the size and then made all the final cuts at home – my version of quality control. Beside do you know how much a 1” 4x8 of MDF weights?.
Top left – Tools for the job note no veneer roller required, just start the iron in the middle and work to the outside.Top right – Using a sponge roller to apply the glue, ensure a uniform thin coat is applied. I applied three coats per surface.Bottom left – As the glue dies it changes color the glue on the cabinet in the background is almost dry.Bottom right – Applying glue to the veneer, I taped the veneer to wax paper you don’t have to worry about the outside edge as they will be cut off. Each piece is individually attached to the baffle with screws. To ensure the lens line up uniformly I had a template made to allow for the predrilling of the plate screw holes. The template is centered on the baffle by using the existing bolt holes for the horn. That was my original plan but it didn’t end up that way (wrong size holes for centering), for me it did not matter as I had not drilled the bolt holes in the baffle yet so I was able to just use the pilot holes.Here is the layout of the templateOnce the lens mounting screw holes have been predrilled it is just a matter of attaching the plates one at a time from the bottom up. But what I really want to see is some pictures of how you assembled that beautiful stainless steel lense.
Did you weld the pieces together, tap and thread them, or use regular old nuts and bolts? You might want to consider making a few pair for some of us 4343/4344 owners, I know that I'd certainly be interested. Regards, Paul from ProvidenceThanks PaulIf any members are interested in the Stainless Steel 2308 lens please PM me, if there is sufficient interest I'll see what can be done – not promising anything at this point.Chris. Can you show how you trimmed the walnut trim in angle on the front?,The trim is chamfered at 30 degrees. Scrap wood is clamped at each end to allow the router bit guide wheel to roll straight off the edge of the box. Once each side has been chamfered you can’t do this for the top or bottom you have to use a straight edged to guide the router. Cause if you don’t the router guide wheel would follow the chamfered edge and a grown man will cry.
The following pictures are from my B380 project but the technique is the same. You just started making the X-overs.??, how did you know what to buy (quality)?,Well let’s just say “I just started assembling X-overs” I’ll leave the making to the experts.I did my research; Google Advanced Search is your friend when looking for information in this web site. Search using “Giskard's equivalent network”.There is tons of information on X-overs within this web with the associated part list.I used the 2405H and 2425J circuits from “Giskard's equivalent network” and the JBL 4344 MKII for the 2123. I have redrawn the schematic from the scanned imaged in the web site. To any experts out there if I have miss-drawn the four 36.0 µF Caps that represent the two 72 µF Caps on the original JBL schematic let me know and I’ll fix. I’m no expert in this area.This is the parts list I used and were sourced from. Well let’s just say “I just started assembling X-overs” I’ll leave the making to the experts.I did my research; Google Advanced Search is your friend when looking for information in this web site.
Search using “Giskard's equivalent network”.There is tons of information on X-overs within this web with the associated part list.I used the 2405H and 2425J circuits from “Giskard's equivalent network” and the JBL 4344 MKII for the 2123. I have redrawn the schematic from the scanned imaged in the web site. To any experts out there if I have miss-drawn the four 36.0 µF Caps that represent the two 72 µF Caps on the original JBL schematic let me know and I’ll fix. I’m no expert in this area.This is the parts list I used and were sourced from.The network diagram has a typo with the capacitors in the 2405 circuit.
The original schematic had a pair of 3.3 uF this is incorrect. The pairing should be 3.3 uF and 3.9 uF.
The parts list in the original post is correct.Below is the corrected schematic. Thx for your answer.you helped a lot!i have one more question for my JBL 4345 clones.beacause i have no 2122h i got one 2123h.can i use this crossover from 4344 MK2 with chassis 2123h and build up the 3145 crossover?:(#53)please help with that too.so i can start to order the parts for the crossover.big thx!!!btw you did a REALLY GREAT job with ur JBL´s.
Just phantastic!My understanding is that the 4344 MKII crossover will get you the smoothest sound out of the 2123 for this type of application. The issue would be the crossover point of the 2245 would have to be raised to 340Hz from 290Hz as in the stock 4345 with a 2122.Most people in the forum don’t like having the 2245 play this high.There is a lot of information on the differences between the JBL vintage 10” speakers here,as they are not considered to be that interchangeable.There much discussion on the 4344 MKII crossover you’ll have to search the forum on your own as it is spread across multiple threads.Chris. Thx for your answer.you helped a lot!i have one more question for my JBL 4345 clones.beacause i have no 2122h i got one 2123h.can i use this crossover from 4344 MK2 with chassis 2123h and build up the 3145 crossover?:(#53)please help with that too.so i can start to order the parts for the crossover.big thx!!!btw you did a REALLY GREAT job with ur JBL´s. Just phantastic!Hi fencki,As I can understand there is an error in the drawing presented on the #53C1, C3, C5 and C7 form equivalent C=36/2=18uF, but from Giskard L=1.8mH, and C=14uF.as hi-pass network -6dB relative to the LF part is round 1.3kHzregardsivica. Hi fencki,As I can understand there is an error in the drawing presented on the #53C1, C3, C5 and C7 form equivalent C=36/2=18uF, but from Giskard L=1.8mH, and C=14uF.as hi-pass network -6dB relative to the LF part is round 1.3kHzregardsivicaIvicaI curious as to why you consider the schematic wrong as the section you are referring to comes from the JBL stock 4344 MkII schematic which has the C5, C7 as 72uF which in a CC network would be 2 x 36uF. Or am I missing something?I was not aware that Giskard had done a schematic for a 2245/2123 crossover if he did could you point me to it I would be very interested in looking at it.Chris.
The capacitor values in the mid filter are for charge couplingThe values are correct when simulating the voltage drive in LEAP.The measured acoustic response in LMS is correct for the 4344mk11 schematicThe use of the 2245 requires an active 3rd order filterSome users have reported using an active 4th order filterhi.can you please explain that, for somebody not that good in crossovers?are the corrected values right, what ivica suggested? Or the original ones former posted?how should the crossovers for the 2245h and 2123h look like if using the 2123h and the crossover for 4344 mk2?i mean the crossover frequencies are different (290HZ in 4345 and 340HZ in 4344)using a 3rd or 4th order filter?can u show a schematic for the usage of 2245h and 2123h?i don´t have such simulating programs so i have to ask the pros here.:)thanks a lot and greetings from viennaslavko. Based upon my experience using the 2123 with the 4344 MKII crossover it does, in fact, work quite well when used within a hybrid 4344/4345 set up. I've done this myself and I have heard Christo's set up. No, it might not meet the ultimate technical analysis parameters, but to my ears, based upon my own 4345 experience and having A-B'd my own 2123 franken version.it simply works quite well.No, the 2123 doesn't sound like a 2122, but both are really great drivers in this context and I am hard pressed to pick a favourite. Hi.thanks a lot for those measurements and test.very interesting for me, because i am still not sure about my decision which crossover to use.because my englisch is not the best i have one or two questions.does that mean, that you tried the 4344 mk2 schematic with the mentioned drivers (with no change of any values or routing)?
(= green line)does that mean, that you tried the giskard schematic (with taking the 2123h section from MK2 for MF) and all other values from giskard? (violett line)if i understood that right, then the original 4344mk2 schematic resullt (=green) looks better for me (maybe not the 'hole' at 10kHz.):eek:thx a lot for your expertiese.best regards from viennaslavko.
They are independent measurement of actual component values where people have used the mid filter of the MK11 crossover and then used the Giskard filter for the horn and slot. I refer to this as hyprid filter (violet)The MK11 filter uses if all values in the MK11 schematic for the mid, horn and slot (green)The reason for people using a hyprid filter alludes me.But someone essentially complained about the outcome after being given advice to use the hyprid filter so l investigated the reason.Of course it is entirely up to the individual what they decide do with their own project.I have posted this information as a heads up.If you want or need individual 'advice' pm me.I'm am usually available with donations of fine red wine for my amazing wife!. They are independent measurement of actual component values where people have used the mid filter of the MK11 crossover and then used the Giskard filter for the horn and slot. OkayIf the weather is okay today l will do some external measurement using the 2245H.The question or what might be term the issue is how will the 2235H and 2245H work with the MK11 passive filter and what is the active filter requirement?The reason for external measurement if you are not familiar is that a measurement in a room and particularly a smaller rooms are problematic to be of any use at 500 Hz and below.
The question of whether the Ashly is deemed a hifi qualify active crossover is questionable but it's a good starting point before you decide to spend US$1250 on a First Watt B4 crossover which l use. The B4 model has a range of custom filter adjustment that make it entirely suitable.Not that I would know anything about a $1250 crossover, but I did consider the Marchand prior to purchasing my first (used) Ashly XR1001. It's worked great for me for over eight years. I had a bit of a problem with dropouts from one section at some point which I traced to a pot on the Ashly that had a dead-spot. I contacted Ashly and they quoted me a very reasonable fee to repair it but also offered to send me a new potentiometer free-of-charge, which I took them up on. I'm still using it without repair just bumping the setting slightly and I've since purchased another excellent condition used Ashly to put in the system while I effect the repair on the original. Then I'll either have a replacement, should I need it, or use the spare to try bi-amped L7s!.
Technical Manual Template
Thanks for chiming in.Like any piece of audio equipment the final choice depends on your own situation and the considerations associated with that such as your technical understanding of how to set these crossover up. Some manufacturers offer assistance.But otherwise the user adopts a Monet approach to passive/active crossover execution with insights obtained from various forum posts. The key is in collecting quality data.As l said the Ashly works, it does get you going and they are accessible.I started with the JBL 5232 off eBay.Other forum members have moved on and purchased the Bryson active crossover, DEQX,.Passlabs and reported audible improvements.There is nothing exclusive about diy or vintage audio.Do what you. I didn't hear that at all and in fact, quite the opposite. Ian, the 'hybrid' came from a mod to a change of the Giskard version and was based upon the lack of 2122 availability.
No mystery there.The combination, properly implemented, works really well up here in this hemisphere! But then, our drainage water flow runs clockwise!:DNow, that certainly doesn't mean other ideas and methodologies don't do well and possibly exceed the intention on paper, at least.:)Furthermore, given that there are LF room interactions influencing at the bi amp crossover frequencies, the bi-amp crossover frequency, give or take 50 Hz and accounting for slope, in the real world, are really moot, IMHO. Fourth order LZ at290 Hz works fine here!. Based upon my experience using the 2123 with the 4344 MKII crossover it does, in fact, work quite well when used within a hybrid 4344/4345 set up.
I've done this myself and I have heard Christo's set up. Curves1.Measurement of Passive system crossover curves (near field) (top)2. 2245 5 Db/ division 1 octave smoothingRaw driverWith passive low passfilter (3145)The peak in the bass can be ignored as is an environmental issue.3. System response 10 Db/division 1 octave smoothingThe gentle rise in the lower end is a function of the ground plane measurement technique.4. 2123 5 Db/division 1 octave smoothingRaw driverWith mid filter bi amp mode5. Simulation of the passive 2245/2123 crossover using the 3145 low pass filter values and the 4344MK11 mid filter.As can be seen this filter sums flat and has the correct phase relationship at the crossover point. The simulation is derived from real data using measurement of the drivers.
The data is conditioned and then applied to different scenarios.This is more efficient than building trial networks.Ground plane measurement- enclosure inverted - mic distance 1 metreLMS - precision calibrated micI have done some preliminary bi amp simulationsThe 3rd order 290 Hz active crossover does not sum flat with an +3 Db hump unlike the passive network. No surprises there.It is important to understand that these humps are phase errors and cannot be reduced or removed with equalisation without causing more problems than it solves.The better way is to design the crossover point to sum flat at a reference point on the baffle(at the bottom of the lens) from a given distance to the test mic.TBC.