A better L112 ??

[Ian Mackenzie]

Just a heads up those 5234 and the 5235 had only unbalanced outputs.

Only the input was balanced.

https://ashly.com/wp-content/uploads...08/xr-1001.pdf

The Ashly based on this tech sheet had balanced outputs.

What this amounts to is that if you are using power amps with balanced inputs (phono 3 tip ring or XLR 3 pin ) the Ashly is going to be quieter over the JBL crossovers. Things like ground loop buzz, cable noise and emi can all shrouded the sound quality particularly at normal or low listening levels.

[BMWCCA]

Just a heads up those 5234 and the 5235 had only unbalanced outputs.

Only the input was balanced.

https://ashly.com/wp-content/uploads...08/xr-1001.pdf

The Ashly based on this tech sheet had balanced outputs.

What this amounts to is that if you are using power amps with balanced inputs (phono 3 tip ring or XLR 3 pin ) the Ashly is going to be quieter over the JBL crossovers. Things like ground loop buzz, cable noise and emi can all shrouded the sound quality particularly at normal or low listening levels.

Thanks. It is my impression that the 5234A came with 1/4-inch jacks. That appears to be what is in the ad. I don't use balanced. I could because I have the Mod-X adapters for the Crown PS amps, but I don't.

Please take a look at this photo the seller sent me of the inside. Are those the two cards in front? I'm sure those numbers mean something but I have no idea.
Thanks:

[Ian Mackenzie]

Yes they are

I could not identify which cards they are. So ask the seller are they 12 db or 18 db cards and what frequency?

You want either a generic 18 db card or the pre determined 515145 cards for the 4345.

I can assist you with setting up an 18 db card for the 4345.

[BMWCCA]

Yes they are

I could not identify which cards they are. So ask the seller are they 12 db or 18 db cards and what frequency?

You want either a generic 18 db card or the pre determined 515145 cards for the 4345.

I can assist you with setting up an 18 db card for the 4345.

Thanks for your help. All the seller knows is that they came with his 4355s.
According to the 5234A tech sheet, the 4355 and 4345 use the same chip.

[Ian Mackenzie]

Okay that means they are most likely the 18 db cards installed as the 4355 and the 4345 used the same pre determined or user programmed 18 db cards.

If the seller is prepared to show the other side of the card this can be validated.

[Ian Mackenzie]

Edit - Update.

I magnified the card tracks and they appear to resemble the 12 db cards when comparing to the JBL card parts designations.
One of the cards has been re soldered at one point.
So that means the seller may have used the original 4350 12 db crossover setting at 250 hertz.

All is not lost..however.

As a stretch these 12 db cards could be updated to a Linkwitz Riley 12 db crossover set for 300 hertz which I know works on the 4345.
See below

Some background.

The passive woofer - mid range crossover in the 4345 was we know is a compromise because the woofer and the mid range filters interfere with each other.

So we know we should bi amp the 4345.

JBL change their ideas occasionally. The former JBL 4355 used a BW 12 db 250 crossover card and the 4343 used a customised BW 12 db card with spread crossover points at 230 and 290 hertz.

The aim of this was to get the systems sum flat in the woofer crossover region. To streamline the situation for user JBL then used identical 18 db cards with both the 4355 and the 4345. They claimed the active 18 db electrical characteristic offered a similar characteristic to passive network for the 4345. However it is a more abrupt crossover transition. Greg Timbers has mentioned the passive filter was compromised. I have measured this and I agree.

Insights
I found the 18 db crossover on the 4345 to be very sensitive to adjustment. After I measured what was a going on I found the passive midrange bandpass filter adds approximately 2-3 db of passive gain to the 2122 mid cone. This translates to the mid cone being louder than it should be.

Greg Timbers responded the 4345 miid L pad (only) should be turned up full when the 4345 bi amp switch is set to external. This partly compensates for the imbalance in the mid cone level and the woofer absolute levels in bi amp mode. The point is that most users would not necessarily be aware of this .

Another possibility has I have hinted at above is the Linkwitz 12 db crossover filter which does sum flat. Unlike the BW filters the LR filter is -db at the crossover region and it sums flat with the electrical phase of the woofer and mid cone reversed. I have personal found this to be subjectively better than the 18 db crossover filter which sounds like the woofer and the mid cones are operating separately on some program material.

The cut a long story short I think the cards in the JBL crossover could be set up for the LR 12 db crossover. If its a bargain sale it would be worth investigating and trying it.

[DerekTheGreat]

How are you using he BX63A to biamp . . . anything? Isn't that dividing network intended for use with the JBL B460 sub? I don't run any subs. What would be needed for my 4345 and what should outperform the Ashly would be the 5234A with the 4345 cards, right?

He's not using it to bi-amp, he's using it as intended for B-460 clones in 8 cubic foot boxes.

Hmm. How is that not bi-amping? The BX-63A is taking the signal, dividing it and then feeding two (eventually four in my case) amplifiers; one for the lower frequencies and one for the frequencies above the lower ones. Sure, the drivers don't all live in the same box like the XPL-200's, but the end result is the same in my eyes- I've got the low end of the signal going to dedicated amplifiers & woofers and the high end going to dedicated amplifiers and drivers. Yes, the BX-63A is designed to work with the B460 and B380 subwoofers. Unfortunately, I am a laymen and don't know anything about the JBL deal with the cards..

Derek, Thanks for sharing and encouraging with your electronic crossover experience. Looking in the Link section of the Forums in the Consumer Tech Sheets section, you'll see a separate entry for the L150A-B. This idiot's cursory reading of the circuit diagram leaves me thinking the A-B network schematic is different in the wiring/arrangement, but the same in the components used, so your mention that your crossover was in the top, leads me to believe they changed the manufacturing technique or supplier at some point, requiring an update to the model designation. I see no other changes based on the Tech Sheets supplied.

Glad I could be of some help. I noticed that anomaly between A-B with the L150's. Like you, I didn't see any 'real' changes, nor did I ever see a "L150B" out in the world. So I guess that means I had L150A-B's and that yeah, they changed something for some reason. I did buy a spare set of L150A crossovers, they looked identical to what you have and what I had. Although I want to say there is a "sloppier" version out there, where all the components aren't arranged as pretty on the board.

[BMWCCA]

Edit - Update.

I magnified the card tracks and they appear to resemble the 12 db cards when comparing to the JBL card parts designations.
One of the cards has been re soldered at one point.
So that means the seller may have used the original 4350 12 db crossover setting at 250 hertz.

All is not lost..however.

Thanks for the detailed assessment.

It looks like a decent deal at $200 but, given the questions raised, not sure if it's worth the experimentation, since the Ashly offers the ability to emulate the Linkwitz Riley 12 db crossover through their "response" setting and to set the crossover frequency for approximately 290 hertz. I suppose only a direct comparison will give answers. But then this box has such limited utility (given the cost of new cards) that I'm not sure I'm up to throwing away money at this point.

I'll give it some thought but I doubt the seller will feel comfortable pulling the cards to see their bottoms. All I can do is ask!

[rusty jefferson]

Hmm. How is that not bi-amping?....

Bi-amp generally refers to an amplifier channel for each driver in a 2 way system that could be either active or passive. The way JBL uses the term referring to separating out a woofer from the other drivers, that are left on a passive network, is unusual but still technically bi-amping I suppose, as what you're doing is probably still technically bi-amping. It's really just semantics.

[Robh3606]

Thanks for the detailed assessment.

It looks like a decent deal at $200 but, given the questions raised, not sure if it's worth the experimentation, since the Ashly offers the ability to emulate the Linkwitz Riley 12 db crossover through their "response" setting and to set the crossover frequency for approximately 290 hertz. I suppose only a direct comparison will give answers. But then this box has such limited utility (given the cost of new cards) that I'm not sure I'm up to throwing away money at this point.

I'll give it some thought but I doubt the seller will feel comfortable pulling the cards to see their bottoms. All I can do is ask!

You should be able to resell especially with those crossover cards. I agree about your if it's worth it concern. Do an E-bay search for just the cards to see what's currently.

Rob


https://www.ebay.com/itm/25573287999...Bk9SR4zX7eKjYw

[speakerdave]

I missed the segue, but I would have to agree a biamped 4345 is a better L112.

[Odd]

I use the JBL 5235 Electronic Crossover which I have changed almost all components inside. And it works well.
Don't think I would buy the 5234A today.
Had a new 18 db printed circuit board made a few years ago.
I think I still have some lying around. They are easy to make.
Everything is described in the manual Ian posted.

[Ian Mackenzie]

Very cool.

[Ian Mackenzie]

I had a look at the spec sheet below and it’s an interesting unit. There is an adjustment for the crossover point to obtain a flat response. Thats a nifty feature.

According to the spec sheet it states 24 db per octave slopes. Does it matter and more to the point would you hear it ? It really depends on the circumstances in which a system is used. Technically its a rabbit hole either way. The whole thing could be technically correct but once it’s put in a real world situation some of that goes to hell unless the user is prepared to use for example a graphic equaliser or some form of bass and mid bass EQ to make the system acceptably as smooth as possible in that frequency region. That requires measuring with REW and a microphone or a dsp based EQ like Dirac. There are pros and cons on either route. There’s a bit of experimentation and work in making it worthwhile. For some it’s a must do but for others not so much. I don’t mind the look of an 31 band graphic EQ. They are a great talking point over a good bourbon. But the question again is do the circumstances warrant that and is the user interested in doing that?

So it’s important to look at any change in the context of the circumstances and what the user wants out of the system.

https://ashly.com/wp-content/uploads...08/xr-1001.pdf

[BMWCCA]

Okay, getting back to the original thread subject: I FOUND A BETTER L112!!!

It's called the L150A.

Almost 18-years ago, just after joining this group, I acted on a for-sale tip and met Don Mascali who helped with the purchase of some L150A near his home. For over twelve-years they sat in my garage in their original boxes, in need of new surrounds and a tweeter repair. Within the last five-years I moved them up to the new house and realized how much of a toll bad storage had taken on them. It looked like water damage with splitting seams, and rotted plinth, but there was no water. Could be termite or carpenter ant damage, since the garage is over 80-years-old. Regardless, they needed more help than new surrounds. So I parked them after destroying the contaminated parts and fumigating them outside. Years later, this month, I worked on the drivers, replacing surrounds on four 12-inch cones, and took apart the smashed 044 to see what could be done. To save time, I replaced the diaphragm with one from a spare, but still had to polish out the tarnished aluminum bodies. That done, I took another cringing look at the cabinets, bought some larger clamps and wood filler and went to work in an attempt to make them acceptable. The surface on some parts looks to have reacted with the styrofoam pieces in the original boxes and the boxes themselves were so destroyed by bugs and whatever they excreted (?) that I had just knocked off the plinth pieces, burned them and the cardboard, and tossed the styrofoam. I forced glue into the spread seams and clamped them as tight as I could overnight. That did not work as well as I thought, but it was better. Then I tried Bondo Wood Filler for the etched top surfaces and sides that were in contact with the Styrofoam, knowing full well that this would be a good time to learn another skill—veneering! But I wasn't ready for that degree of perfection. I made new plinths out of an old mahogany futon frame I had replaced but held onto because the wood seemed very solid. I ripped the rails with a table saw, mitered the sections with a compound miter saw, and bought a cheap drill press from Harbor Freight to drill and countersink the 1-3/4" plinth parts to attach them to the bottoms. I sanded, I stained, but the best I could come up with was a finish that looked more like Wormy Chestnut than JBL Walnut. Some Howard's Restore-A-Finish and steel wool created an acceptable surface and I already had the magic Krylon that is a dead-on match for JBL semi-flat black. It was time to put them back together.

I still needed one terminal cap, but I've had a salvaged pair of L26 that I'd paid nearly nothing for and hadn't touched in way too many years. I asked them to donate one black terminal cap simply because I always like old JBLs to be as near-original as possible. I hate the terminals but use a nice simple adapter that goes from braided wire to female banana jack, and just leave them attached. And then I plugged them into the Crown Studio Reference-II and put on some Jennifer Warnes "The Hunter" and cued up the track "Way Down Deep". OMG, as the kids say!

I spent the next several hours swapping CDs and speaker cables comparing the L112 and 240ti with the newly re-commissioned L150A. I referred to the 150 as "humbling" in that it humbled both other capable JBLs, as well as humbling me for treating them so badly for so long. But I was near tears to think that I had eventually saved them, and finally got to hear them. Now on to the next project!