One L300 louder than the other. New crossovers needed question for the experts?

Hi Guys. I fixed the loose wire that made one horn stop working from my last post here. Gaining access to that mid range horn compression driver was/is a lot of fun. You have to remove around 12 large machine screws, and then a second inner wooden access panel that is a bear to remove easily. It really fits in there very snugly. These L300 cabinets were very well made honestly. I have had to do this 3 times now. Each time I move the speakers that same compression driver wire gets loosened on that one driver. These speakers were last owned by the original bass player for the 1970's rock group "Duke and the Drivers." He told he bought them from the original owner around 1980. I basically agreed to buy them sight unseen knowing nothing much about them except for posting a question first on AA. I then rented a big truck with a rear ramp to load them easier with my bad back using my 2-wheeler and rope only. I drove a few hundred miles round trip to snag them. Amazingly almost 5 years ago now they were for sale for $500 for many weeks in the local WantAdvertiser before I found the ad for them. He told me that everyone calling him about them was only willing to offer him $100 to 250 cash for them. I told him on the phone I would be very happy to pay him his $500 asking price for the pair sight unseen which I did. At that time I was not working so $500 was a lot of money to me. He told me that he really wanted them to go to someone who would enjoy using them more than for the highest price. I mentioned that I owned vacuum tube amps and he said they will sing with as little as a 10 wpc tube amplifier. That deal turned out to be very lucky for me at that point in time. But ever since I owned them I have always had to adjust the L-R speaker balance of my preamplifier(s), or receivers a lot to favor one speaker to equalize the sound from these L300 speakers. I have owned them for almost 5 years now. They sound very good when the balance is adjusted and the horn is working.. :) But now I am setting up my very first home theater setup using them for my two front speakers. I will be using my pair of L100T3 for the rear and the new higher end L series center channel speaker. I have just bought a nice used working JBL bass bin also. How can I overcome the problem with the L300 sound, or speaker imbalance? I have used multiple tube amps and a large solid state receivers also and still one of my L300 speakers plays a lot louder than the other one.

I do not want to chop up the original crossovers. I would rather buy a new pair of crossovers. Does anyone sell crossovers that will work with my L300 speakers? I do not want to go through biamplification (or with these tri-amplify them) again. I have another pair of the 4875c4(8) like the ones in the link below. The only difference is I am using tad td-4001 2" compression drivers in the 2360A horns. These speakers were cobbled together over time for my Dad who is profoundly hard of hearing. With these 6' tall horn speakers he could for the very first time since WW2 hear a femal singers voice. Seeing him smile listening to his classical music was worth every penney that I spent on the parts separately to build them. I have them biamplified just like they were designed to be. I am using a Marchand xm-121 vacuum tube active speaker crossover using Welborne 45, and Welborne 300b mono blocks to power them. They are the nicest sounding speakers we have ever heard with no horn shout at all. The 31" x 31" JBL 2360A biradial horns are simply amazing. I have also driven them with a passive crossover using only the 1.7 wpc 45 mono blocks and the bass was very fast, full, and it went pretty darn low to my ears. http://www.jblpro.com/pub/cinema/4675c_48.pdf

So with my L300 can anyone point me towards someone who sells a set of crossovers for my speakers? I am going to power my home theater with a Butler model 5150 "sand (solid state) and triode" hybrid amplifier at 150 wpc into 5.1 channels. I am using a Fosgate FAP-V1 vacuum tube dolby 5.1 sound processor/preamplifier. I do not want to go with another Marchand 3-way active crossover for my L300 speakers to make my system even more complicated than it will be now to set up properly. I would rather buy new L300 crossovers and keep the original ones intact in my L300 speakers. Can anyone here able to point me in the right direction for new speaker crossovers? If anyone knows someone I can pay who can build me a pair of crossovers, or a kit I can assemble that would be sweet also. I wanted to use larger rear speakers but the room is not all that big for our home theater. Until my problems are worked out I am only using my L300 alone with the volume balance adjusted to favor the one side for now. Shipping these 140 pound monsters out would be a killer. I would much rather buy new crossovers for them than ship the whole speakers for repairs. I would have to have them crated and strapped onto pallets to ship them out. That would get very ugly and painful for my fused and laminated spine. Thanks a lot folks for reading this. I did find the article on rebuilding L300 speakers on the web. It seems the original crossovers in these L300 Summit speakers are not so very easy to open up I read. So simply replacing them sounds like a far better option for me right now at least. John C. - Framingham, MA

I would be surprised if it is the xover but who knows! Before jumping to the xover swap I would:

1. Confirm the Mid & UHF LPads are at the same setting in their range of motion - check by rotating them through their full ranges, not just looking at the scales as they could be sitting in there rotated. Also consider lubing them with WD40 or equal contact cleaner if they are scratchy/oxidized as that will mess the sound up (lay L300 on back, pull woof, stand back up, place cloths on cross bar and floor to soak up drips, and squirt lube thru WD40 extension tube in vent slots on back of both controls either via woof hole or rear access if you pull the LE85's as well)! Some cleaners you do not want to breathe in but WD40 is not bad.
2. Confirm each driver is correct to see if any swapped-out drivers or diaphragms are the sonic culprit, in which case the xover swap would be a total waste. Each of my drivers (woof,mid,hi) test about the same, 6 ohms DCR or so. Pull the leads from the xover off of each to test DCR of course.
woof should be a 2231A
mid - LE85 label 8ohm - should have red wax over rear screws otherwise dia has been looked at and probably replaced. Original aluminum dia has roll surround and my LE85 with a 2425 Ti dia is a little bit louder.
UHF - 077 - also check for foilcal damage indicating removal for dia access.

I see a pair of N333 xovers recently went for $350 or so on EBay so that may be an expected price if you go that route. I have seen 3 pairs on EBay in the last 4 months.
- Roy

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Originally Posted by remusr

Also consider lubing them with WD40 or equal contact cleaner if they are scratchy/oxidized as that will mess the sound up (lay L300 on back, pull woof, stand back up, place cloths on cross bar and floor to soak up drips, and squirt lube thru WD40 extension tube in vent slots on back of both controls either via woof hole or rear access if you pull the LE85's as well)! Some cleaners you do not want to breathe in but WD40 is not bad.
- Roy

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FWIW
I don't know about for L-pads, but i do know that you do not want to use WD-40 on the pitch slider of Technic 1200 MKII turntable... it will absolutely destroy them....

for L-Pads, most ppl I have read recommend De-Oxit or something like that

WD40 is noncorrosive and great for contact cleaning as well as lubing door hinges and cleaning lube off of my bike wheels! Recommended by my electronics guy and others.

nice to know.... thanks

OT trivia bit;
WD-40 stands for Water Displacement, formula #40, and was originally intended for application to aluminum aircraft to reduce oxidation formation. Evidently the 39 previous formulas were unsuccessful....While it's effective at preventing oxidation, (among other things) other products, particularly Caig DeOxit are better at removing it, and leave no oily residue to collect dust.

JP - how is your investigation going? And do take care of your back moving and twisting the beasts around! Tell me how it works out and if I can help such as measuring/verifying anything on my L300's. I have a spare set of N333's that I am saving for a build that I can do some measurements on.

Moldy - interesting trivia! I will pass that one on at the dinner table! Thx! Related to cleaning my L300 LPads, I had a too long discussion with an old but good electronics repair/tweak whiz and got lots of recommendations, along with health warnings for the aggressive/expensive deoxidizers, but when I asked if WD40 would do, he said it would be good enough and safe so that's what I used and it has worked so far. Not much dust in that box, but maybe an issue for mobile or outside use. Not like an ArmorAll product tho!
- Roy

You can't go wrong if you build/have built the crossovers in "I think We May Have a Keeper Here" which were based on the 800 Hz L200 crossovers with the 7,000/8,000 Hz N7000/N8000 added on-board.

Use the 0.3 mH chokes on the tweeter and congegate horn unit for the slot radiator.

Zilch has done extensive testing on mine and his own that he built after reviewing mine and notes that these are sweet and work with just about anything that calls for x-over in those ranges.

http://www.largescaleonline.com/eima.../Crossover.jpg


http://www.largescaleonline.com/eima...Crossover3.jpg

Hang on now ...

While I share Todd's enthusiasm for our "generic" crossover project, I'd not conclude that new crossovers are the answer at this point.

Or that these particular ones are even applicable to L300, without further verification.

10 kHz is the better crossover frequency for the slot.

[Workin' on that part....]

That's DIY, tho, and doesn't belong here.

Figure out why one is louder than the other as others are suggesting.

Drivers? A particular one? Crossover? L-Pad?

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Originally Posted by toddalin

You can't go wrong...

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I think you could go wrong...

Before jumping in there and building some new networks that may or may not be an actual equivalent, I'd track down the actual problem.

From your post I am not sure that you have confirmed that the problem is within the networks. You do not need to open them up to determine this.

FWIW: I was helping a fellow forum member with his very clean 4343s and we discovered that one of the 2420s (Identical to the LE85) was putting out less output and more erratic output than the other... it did this even after changing diaphragms. He was able to buy a replacement 2420 with no diaphragm on eBay for under $50... we installed the new diaphragm, tested it with CLIO and it performed flawlessly. Now both channels perform up to spec.

The driver in question had red seals intact and didn't appear to have ever been pulled from the cabinet... there was nothing obviously wrong with it. We did not check it's magnetic strength since we didn't have a gauss meter.


Widget

Quote:

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Originally Posted by jpchleapas

(so many words)... But ever since I owned them I have always had to adjust the L-R speaker balance of my preamplifier(s), to favor one speaker to equalize the sound ... (so many words) ...and still one of my L300 speakers plays a lot louder than the other one. ... (so many words). Until my problems are worked out I am only using my L300 alone with the volume balance adjusted to favor the one side for now.... (so many words)

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Hi, JP... :wave:

Two things:

- first, I agree with Widget. Try and source the reason for the imbalance. You may have tried all this, but have you narrowed-it to only one specific cabinet? Have you swapped/replaced the speaker leads?

- second, is there a difference in tonal quality, L-to-R? Or is it merely a "gain" issue? (this gets to Widget's question: are all the elements working equally well in each cabinet?)

- third (didn't I say three...?), many here measure their contribution by number of posts. We've never had anyone come in and post their entire situation, past and future in one post! Interesting concept! :rotfl:

Quote:

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Originally Posted by boputnam

Hi, JP... :wave:

Two things:

- first, I agree with Widget. Try and source the reason for the imbalance. You may have tried all this, but have you narrowed-it to only one specific cabinet? Have you swapped/replaced the speaker leads?

- second, is there a difference in tonal quality, L-to-R? Or is it merely a "gain" issue? (this gets to Widget's question: are all the elements working equally well in each cabinet?)

- third (didn't I say three...?), many here measure their contribution by number of posts. We've never had anyone come in and post their entire situation, past and future in one post! Interesting concept! :rotfl:

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Sorry for the complete past and present description of my stereo.. I have not mentioned my future goals yet. :) I do have a speaker polarity phase tester. It showed me that my speakers were/are wired correctly from the amplifier. The test CD it came with sends a test pulse through my speaker drivers. A hand held 9v battery powered box flashes either green for the speaker driver of the driver is correct, or red for backward wiring when you aim it at the center of the woofer, or other driver while the test pulse signal is playing from the test CD polarity test track.

I have listened to each speaker up close and the horns are working on both, as are the tweeters, and the woofers. When the one midrange horn compression driver wire gets loose the speaker definitely has a problem that I can hear quite easily. Once I reconnect that loose wire the good sound returns from that same speaker.

The one speaker is definitely not as loud as the other one. I have reversed the speaker wires from L-R and R-L using multiple amplifiers to see if the problem was speaker wire related, or a bad channel in one of my amplifiers. It is not and that one speaker is playing lower than the other at all times. When I do match the speaker balance by hand (or by ear from critical listening with my eyes closed adjusting the balance until the sound is at the same level from both speakers.) I have to buy a hand held sound meter for my Fosgate fap-v1 tube surround sound preamp/processor to set it up correctly per the manual for it. I will then use that meter to get a more accurate reading as to how many dB softer the one speaker is playing than the other one. I do not hear any other obvious problems with the one lower playing speaker. It does appear that the tone controls for the one speaker are not working quite as well on that same speaker. That may be the right place for me to begin by cleaning those pots. I have some spray contact cleaner, and a separate spray lubricant that I can try later on this week. I am also the only caretaker of my elderly Dad so it might be a few days before I can get to try this. I am thinking of removing the woofers to get at the tone controls of both speakers. I have never taken these speakers apart before. I have removed drivers before from speakers. But not from a 135 pound speaker. So let me clean the tone controls first and then report back in a few days. Thanks everyone for all the replies. I do appreciate it. BTW, there is a pair of L200 empty cabs for sale on fleabay, and the shipping is only $70 each. I am not a huge fan of the L200 but using the cabinets to build a clone 2nd pair of L300 clone speakers would be a blast. The factory or JBL dealer upgraded L200 speakers were supposed to be a very good sounding speaker I have read. Then again before I add more audio projects I want to fix these L300 speakers first. I will use my cordless drill to remove the woofers. Hopefully I can then access the tone controls easily to clean and lube the controls to see if that helps, or if I see any obvious loose, broken, or dangling wires inside. Again thanks guys! I will give an update in a few days. I still have to believe that 2 new crossover networks for both of my speakers is not a bad idea. The original capacitors in my crossovers are getting close to 30 years old now. At least the new to me JBL L100t3 speakers are both working correctly, and woofers were both sent out for repairs. Too bad they are not the speakers giving me the problems. They would be far easier to take apart at only 55 pounds each. John

John - I would not use a cordless drill to remove the phillips head screws holding the woofers in case you slip and gouge the woofer cone. A #2 hand screwdriver is safer. My 11-step procedure...
1. Remove the speaker wires.
2. Lay the L300 boxes on their backs on carpet ( with help as needed).
3. Place a cloth on the baffle to one side of the woofer baffle.
4. Put a cloth over the horns & lenses in case you drop a screw there.
5. Remove the woofer screws with a hand screwdriver and watch the screws do not hang up on the external gasket material and push the T-nuts off the inside of the baffle. Wiggle the woofer or remove those ones last while lifting or shimming up the woofer frame so they don't push the T-nuts off.
6. Lift the woofer stright up, may have to rock it to unstick it, and set in on the cloth.
7. Write down which color wire goes with which terminal and remvoe the wires by depressing each spring terminal. Both speakers should be identical or that could be one of your probs.
8. Set the woofers on a table or other safe place, preferably cone-down if you have a cat.
9. Lift the cabinets back on their feet and proceed as I noted before to lube the LPads. You will need a flashlight inside. Taking the LE85 rear access panel off will allow someone to help you line your spray tube up with the LPad slot holes. Make sure you lay some cloths around to soak up contact cleaner drips and soak them well while rotating them.
10. While the LE85 panel is off, check the other drivers are correct and "virgin", remove their leads and measure their DCR's and ensure all wiring is correct phase and identical for both speakers.
11. Block the woofer hole if you have cats and let them dry for a day before laying them back down and reassembling.
- Roy

Hi,

If your drivers are Alnico they might require remagnitizing.
Or the woofers could need a complete retrofit. Voice Coil, Cone,New spiders etc.
Both drivers have to be done simultaniuosly by a professional speaker
repair tech. He does not need your XO to do a perfect match. The Xo is not important for him.

Good luck.

With his SPL meter, John should be able to easily determine which driver, or combination of drivers, is not putting out. As others have above observed, isolating the problem is key to remedying it.... :thmbsup: