New member hello & first question about L220s

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01-30-2021, 11:23 AM
enelson14

New member hello & first question about L220s

Greetings to all, I have a new-to-me pair of Oracles that followed me home and I have some questions. As soon as I got them I had the 14s refoamed by the local speaker service, they needed it anyway, since the existing ones had completely separated from the cones. I was hoping there would be an improvement in bass response, but there was not, which leads me to my question. I have to turn the mid and high pads to about 1 or 2 to balance the lows. I did a rough exam with pink noise and a spectrum analyzer, and these units don't really have much output below about 100Hz. This can't be right, right? Any suggestions as to what to check or do next?

Also, I had a question about the serial numbers on the front tags. This isn't a matched pair, but still, one tag has the serial in white stamped print on the black tag which is what I would expect to see. The other has the numbers stamped into the foil tag as if with a typewriter, none exactly in a straight line. It's kinda suspicious looking. Was this style of marking for serials used as well, or is it possibly some kind of repro?
01-30-2021, 02:24 PM
Robh3606

What condition is the passive radiator the PR15C. You should also have foam surrounds on them as well. If you take the passives out there should be disks on the center to add weight and lower the resonance frequency. The passive radiator acts like the port in vented cabinet if it's too stiff or light it will effect the low bass.

Rob:)
01-30-2021, 04:28 PM
enelson14

Quote:

Originally Posted by Robh3606

What condition is the passive radiator the PR15C. You should also have foam surrounds on them as well. If you take the passives out there should be disks on the center to add weight and lower the resonance frequency. The passive radiator acts like the port in vented cabinet if it's too stiff or light it will effect the low bass.

Rob:)

I should have mentioned that, the PRs were refoamed at the same time. All the weights are in place. I had all them out & redone at the same time. All were coming loose. The seller didn't know their history, but my estimate was the prior surrounds were about 20 years old as they were clearly not original. They were not very well done, with one of the LE14As the spider was pretty much bottomed out against the top plate at rest. After reinstalling the refreshed drivers & PRs, there are no air leaks around the baskets and the moving parts all seem in order with no rubbing or any physical issues.

My next place would seem to be the crossovers, but I saw another thread on here by someone who had a similar issue. There didn't seem to be a resolution posted there. My rudimentary poking around the xovers leads me to believe that all the caps are at least close to nominal, and I don't think the pads are burnt, although if someone could detail the procedure for checking that, I could be sure.
01-30-2021, 09:56 PM
jbl4ever

Hello and welcome to the LH site. When you reinstalled the woofers did you by chance reverse phase? If I remember solid green to positive post. Are the woofers LE 14H or 14A. If the lpads are burnt you would know by turning the dial and it would be very rough and barely move and sound crunchy. Also do you have a low cut filter engaged in your system?
01-31-2021, 03:29 AM
macaroonie

Sounds to me like the spider has been at rest for a long time in an off center position. That plus new foams will add up to the driver being ' stiff' physically.
I would suggest that you go online and get a 30 Hz tone and run that through your system at low level for as long as it takes to loosen things up and to reset the spider.
There are sig gen app's for smart phones that will get you the tone reqd.

Put simply your drivers are needing run in. No rubbing ?
01-31-2021, 09:47 AM
enelson14

Quote:

Originally Posted by jbl4ever

Hello and welcome to the LH site. When you reinstalled the woofers did you by chance reverse phase? If I remember solid green to positive post. Are the woofers LE 14H or 14A. If the lpads are burnt you would know by turning the dial and it would be very rough and barely move and sound crunchy. Also do you have a low cut filter engaged in your system?

I dont think I reversed the connections, if I inadvertently did so, they would both be that way, so still in phase. Both drivers are LE14As. I do see now in the crossover manual that the inputs & outputs of the crossover are black to black, essentially. But what is the polarity of these drivers? Are they old school "positive to black terminal for cone out?" Doesn't really matter here, but I hadn't thought about that before.

The pads are smooth in operation and control the levels exactly as they should, with both down, the only sound is from the LF driver. Using the preamp output of a Nikko Beta III, it only has the 40 & 20Hz HP filters, and that is not enabled. The only other speakers I have been able to compare using the same amplifier and pre-amp are OLA Advents, and even they currently have more "kick" than these JBLs.

Quote:

Originally Posted by macaroonie

Sounds to me like the spider has been at rest for a long time in an off center position. That plus new foams will add up to the driver being ' stiff' physically.
I would suggest that you go online and get a 30 Hz tone and run that through your system at low level for as long as it takes to loosen things up and to reset the spider.
There are sig gen app's for smart phones that will get you the tone reqd.

I have a Hewlett Packard 3320B that I could use for this, might be an excellent way to drive the neighbors crazy for a while.
01-31-2021, 02:54 PM
JeffW

I've owned L220a before, they had plenty of bass well below 100Hz, there's something out of whack with yours if they aren't producing any. Not sure what the problem is (out of polarity woofer wiring was going to be my guess), but it's not normal.
01-31-2021, 06:29 PM
grumpy

JBL foilcals being mechanically stamped is not weird. Perhaps there was a transition between when the two were built.
At any rate, sounds like a very less important issue than getting your bass on.

If you send a tone to the speaker, can you tell (as you gradually lower the tone frequency) where the LE14a essentially stops moving and the passive radiator takes over?

One former member thought the L220 was tuned to 26Hz with the stock 100g weights (and 40Hz without).
Which makes some sense as the LE14a free-air resonance is -supposed- to be 26-28Hz (another thing you could check to see if it's even close).
I have not verified any of this, nor do I own any form L220 L220a L222 of this speaker.

From another former member: "It had a frequency range of ~ 32 Hz to ~ 20 kHz ( -6 dB downpoints )"
I don't recall a lack of bass being something ascribed to this system.
I do have the little buddy version (L150a), and while the bass can be undistorted... which can at first sound like a lack of bass, it is very much present.
Have to wonder a bit about those drivers and their past life... Mac's advice is certainly worth a ponder.
01-31-2021, 06:54 PM
macaroonie

I have a Hewlett Packard 3320B that I could use for this, might be an excellent way to drive the neighbors crazy for a while.[/QUOTE]

Erm no , dosnt have to be loud , you just need to exercise the suspension , flex it like doing press ups.
I've done it several times with drivers thsat have been stored on their backs
actually if you have a driver that is semi locked backwards do this face down with a couple of 2x4's supporting the cabinet.
I repeat , it does not have to be loud , driver only needs to be moving.
Trust me it will loosen up.
01-31-2021, 07:01 PM
Robh3606

Yes this is a bit odd. I actually used Le14A's as subs in 4 cubic ft boxes for years and the had plenty of kick. I still have them and they work just fine. Can you check the woofers for free air resonance out of the cabinets?? Also please post pictures on the drivers. If they were original foamed LE-14 the foam is on the back. The original Lansplas were on the front with the C inverted.

Rob :)
02-04-2021, 10:34 AM
DerekTheGreat

Quote:

Originally Posted by grumpy

...From another former member: "It had a frequency range of ~ 32 Hz to ~ 20 kHz ( -6 dB downpoints )"
I don't recall a lack of bass being something ascribed to this system.
I do have the little buddy version (L150a), and while the bass can be undistorted... which can at first sound like a lack of bass, it is very much present...

"..the little buddy version.." LoL

I also own the little buddy version and the bass is very much present. To my ears, the L150A has better bass and bass quality than my XPL200's. Stock, the L150A's (at least mine anyway) had 40g (four fiber discs) per PR300. I experimented with that quite a bit and found a total of 58g per PR produced the most satisfactory bass tone and depth. So if the L150A has great bass, I'm sure the L220 with it's 14's should be able to pound harder. Never listened to them though.
02-07-2021, 01:43 PM
enelson14

Here is a picture of one of the refoamed drivers. It is an LE14A, serial 97628. Please let me know if this was not done correctly, it wasn't particularly cheap to have it done.

http://i.imgur.com/lkM6fRdl.jpg

I currently have them running at 31Hz at a low level( cant really get a lot out of the only spare amp I have available, an ST-70A.) I guess I'll reevaluate them next weekend and report back. Any other questions, or things I could try or check?
02-07-2021, 07:31 PM
JeffW

That re-foam looks good to me - the dust cap looks ... different. But that shouldn't make any difference in the bass department.