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New JBL 7 Owner Has some Questions.

S

scottie_uk

New Member
Hi, I am a long standing lurker but infrequent poster. Recently near me I scored a pair of JBL L7 for $400 which I was allowed to test at the sellers home powered by some cheap surround sound amp to show they work. I had been reading on here how much these speakers are appreciated by those who own them. I was impressed by people's comments on their authoritative lows. I'm not a bass head, but I do appreciate tight low end extension. I got them home, and realized just how huge these things are, they are divorce big, especially so coupled with their placement requirement of 3 feet from walls on back and sides. That in itself made me reconsider my purchase and ask the seller for a return (they are ok with it).

So my amplification a Forte 1A (80's Class A transistor amp from Nelson Pass in fine fettle), is obviously not up to the job as the low frequencies were washy and not well defined on the L7 with the mids and highs awesome. So I tried bi-amping with a modest but versatile Niles SL245 distribution amp, the 1A on mids and highs and the Niles on the woofer. The Niles did not like the speakers going into protection quickly on the first thump. Wired the other way the 1A could not provide volume or definition in low frequencies, and the Niles did not have the definition of the class A for mids and highs. The speakers are amazing on mids and highs, and the only way I found to make them sound vaguely decent on lows was to run them from my Sony surround sound amp.

So I'm at a cross roads, do I sell them on, return them (the seller is ok with this), or do I spend another $500 on a used Adcom GFA 555? Will that resolve the bass issues, or is it just that because my listening area is only 13-14 foot wide (9 foot high) that my speakers are simply too big for the space?

For context I have an audiolab 8000C preamp, SL12010 turntable, and Denon DL110 cart.
 
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My L7s aren't in a large room, and when I'm listening to them they're only a foot off the rear wall. When I'm not listening to them I push them back against the wall out of the way. They're not as placement critical as a lot of people would have you believe, so just experiment and see what works in your room.
I would think that 50 watts of class A power would be enough to produce plenty of bass, but to be honest I know nothing about your amp so I may be way off base here. That being said I'm using 300 watt Kenwood L-09M monoblocks to feed the L7s and the bass will blur your vision at elevated listening levels. Are you sure the 12 inch woofers are working on yours? I honestly can't imagine them being bass shy if they are. I'm sure there will be other people that weigh in here on your post with better info and solid advice, but speaking strictly from personal experience the L7 is an exceptional speaker and mine aren't leaving my main system.
 
I, too, am wondering if there's something amiss in the bass section of the L7s here, whether it be the LE120H woofers or in the crossover.

Nothing there should be making any reasonably- sized amp, in decent condition, shut down. That's an 8 ohm woofer, and a very normal-topology crossover section. I could see, if it was something unusual like an old Infinity dual-voice coil woofer setup (those could go to very low impedance in some places in the spectrum), or such- but this shouldn't be causing that type of havoc with amps.

In this case- the "uncontrolled" bass could be a symptom of something else being wrong- bad caps, a partial short, or something.

Regards,
Gordon.
 
I don't know about the Adcom but you should not return them unless you can determine there is some sort of driver issue. I have been looking for a pair for a couple years and I have no idea what I'd do with them (just want them) but I had the 590's for awhile and the L7's might best them. The 590's had wonderful bass but yes they are rather tall. The L7's are shorter. Can you borrow a larger amplifier? What speakers were you using? How long have you had the Forte 1A?
 
I have just had an agreement from a seller near me to let me demo an Adcom GFA555 in my home. So that is what I am going to do first before I make a decision. I have found now a placement for the speakers that is less obtrusive. I was able to run the speakers from my Sony surround sound amp and I was just amazed at the imaging and quality these things had. Given that did not trip out, I can assume they might be ok. I can only imagine a more powerful and music intended amp will open them up even more.

The reason why I think the Forte 1A amp will not be sufficient is that it is 50 watts which is not a lot of power for such a large pair. Therefore possibly the bass speaker can overshoot and undershoot without much control. If I am wrong in that assumption do let me know.
 
I still wonder if the Forte is acting as the proverbial canary in the coal mine, alerting us to a possible issue within the speakers.

It may be that the Sony doesn't have as sensitive of a protection system- which may be "ignoring" the problem.

Might be worth simply pulling the woofers and looking at them (especially flex-lead wires and terminals) and the crossovers, to make sure nothing untoward is afoot. If they were mine, I would definitely be taking a look!

Regards,
Gordon.
 
Just another take-off on Gordon's suggestion. If you are nervous about taking the woofers out you might try the L7's one at a time because if one trips the protection circuit but the other does not - that would be a good clue. If both trip it, I'd lean towards the Forte is either ill or just can't handle the L7's which might be odd but....

When you get this sorted out you will be smiling ear to ear. As I mentioned I think the L7's might best the 590's which are wonderful in their own league. My son now has the 590's and he loves them. Just fyi he didn't get them for free. I don't have a sign in my house that says free audio equipment.
 
There is definitely some problem with the woofers. The left one will blow a fuse or send an amp into protection when ever the bass section is powered independently. The only thing they did well was mids and highs and spacial imaging. Even the one that does not blow fuses sounds kind of flabby and loose and not great just like the left problematic one does. This weekend I will take them back. I find my Vienna Accoustics Grand Bach far more musical and far less imposing.
 
So sorry to hear that, they would’ve been a great speaker, but apparently the previous owner or owners were not kind to them. The great news is- the seller is letting you return them.
 
Yeah me too. There is I guess a chance I would salvage things, but I do not want to cause more issues and then have the seller blame me when I bring things back.
 
Something's wrong. I have two pairs of L7 and could not be more pleased with them. I've run them off Crown D150 and PS200 and PS400 with great sound. I've also run them with my Crown Studio Reference-II, but you don't NEED anywhere close to that much power. 75w should make them sing. Too bad they're giving you a hard time. I'd take them back and let the seller demo them to you with his stuff.

Did they come to you with the connecting bars in-place on the input terminals, the ones that connect LF and HF inputs? Are we sure they've not had the blue-wire mod in the internal crossover to make them truly bi-ampable with an external active crossover?
 
Yes they came with the bars in place. I demoed them on the owners home theatre amp so I could hear they at least worked, but the system was weak so I presumed more power would get more bass. It did a bit but I would say it still was not well defined. I never thought to look inside at that blue wire, I've read about that, if that was missing is that what could be causing fuses to blow, when the low frequency drivers are powered individually? Is that what also might be making the sound muddy? Let me know as I am returning them tomorrow and I have some time to test this.
 
If the bars were in-place I would assume no internal mods were tried. Blowing fuses on your amp sounds to me like wiring problems or at least try another amp. You have not shown us the rear with your wiring connected but I also assume you know how to do this without shorting your amp outputs?
 
When the left bass speakers are wired independently, it always blows a fuse, or trips the protection circuit what ever amp is used. I've tried four so far, and one I know was powerful enough to satisfy the speaker's apatite.
 
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Ive been playing them, and it seems like I must increase the bass unnaturally to get anything closely that 'authoritative bass' others have mentioned, but its not tight. For example when streaming from my phone, in my streaming device, the left most slider 31Hz, on the EQ needs to go all the way up, the next one 63hz is boosted half way. Then it provides bass like you'd get from a low end subwoofer of the 90s. Actually turning all down and 31hz up I'm hearing very little action. They seem to bottom out at somewhere between that and 63hz.
 
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One final update, as some suggested I took bass the diver out, it looked ok but I took off and reinserted the bass connections.

I took the back of to check the cross over for the low frequency. It looked fine too the two orange large capacitors looked fine and both were testing 6ohms in circuit. The two small white ones looked fresh as a daisy. The blue white was connected from the common to the normal. Both the left and the right side bass circuits were testing at 6.5 ohms from the speaker terminals. Now I've put them back together, the left one no longer sends the amp into protection. So I really cannot say what is a miss, at least they are behaving symmetrically. Possibly then they are working?

I did try that trick one poster on AK spoke about, that is driving the speaker until warm and generally massaging the cone fully inwards a couple of times. It helped a little but not enough.

I enjoyed listening to them tonight when I put a subwoofer between them which shows they just are not putting out enough low frequency I should not have to do that given their reputation. So its either the speakers are not working well, or my room is just prone to standing waves and not suitable for such a large side firing speaker. That said when I run the bass drivers solo, the bass is present but muffled somewhat, there is sub-bass (40 to 31hz) in them but not much.

I have them out 3 ft at the back, and 2ft on the sides. driver to driver they are 6.5 feet apart.
 
In my house, the rest of the residents constantly tell me to turn-down the L7 when I play them because the bass is strong throughout the house and even upstairs. I resolved that issue by using the L5 in my TV room. Far fewer complaints. When will you try them with another amp? :dunno:
 
BMWCCA I truly believe you and that was what I wanted to happen. I have tried several amps on them.

First my class A Forte 1A at 50 amps per side,
Then a Niles audio SL245 at 70 watts per side,
Then one of Sony's better surround sound systems,
and finally I tried them with a loaned Adcom GFA555 with the intention of buying it if made them sing at all listenable frequencies.

In all cases, the stereo separation and image was the best I've heard, but the low frequencies at 100hz were not tight, and below 61hz they rolled off quickly. A small Klipsch subwoofer did better. So either they are faulty, or my room is just not a good match for them.
 
scottie_uk said:
BMWCCA I truly believe you and that was what I wanted to happen. I have tried several amps on them.

First my class A Forte 1A at 50 amps per side,
Then a Niles audio SL245 at 70 watts per side,
Then one of Sony's better surround sound systems,
and finally I tried them with a loaned Adcom GFA555 with the intention of buying it if made them sing at all listenable frequencies.

In all cases, the stereo separation and image was the best I've heard, but the low frequencies at 100hz were not tight, and below 61hz they rolled off quickly. A small Klipsch subwoofer did better. So either they are faulty, or my room is just not a good match for them.
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What about phasing? Don’t trust the speaker connector colors… could be reversed or the amp could be reversed. Do you how to test if they are in phase or not?
 
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