Just Obtained a pair of JBL L100T3 Speakers

[richiem46]

My JBL 100T3 adventure continues. We are in Michigan for the summer now and a cousin drove up from Florida and was nice enough to bring up my Sansui AU-919 and the original woofers from the pair of water damaged L100T3's I have down there. The T3's sounded great in Florida and I was excited to mate the original woofers with the more physically pristine T3's here in Michigan.

Before making the woofer swap I listened to the T3's with the replacement woofers driven by the AU-919 for a while. They sounded good but just sensed that something was missing. I have a pair of JBL L36's that I just replaced the replacement woofers with the oroginal JBL woofers. When Iistening to the L36's driven with the AU-919 the sound was amazing, not fatiguing at all. I was very pleased and figured that the L100T3's would be even better as the damaged units in Florida had sounded so good.

I then went to swap in the original LBL woofers into the L3's hoping I would see a noticeable improvement in the sound quality. Once the swap was completed I listened to the T3's with the original woofers for a bit. They sounded better balanced tone-wise but the same something was still missing.

A few other things I observed, one of the JBL woofers had a small tear in the foam surround so I figured while I had it out I would re-foam it. I use a 1.5V AA battery connected to the speaker to push the cone up and away from the speaker frame to facilitate applying the glue to the speaker frame. Normally connecting the + pole to the + speaker terminal causes the cone to be pushed up and away from the frame. With these woofers the opposite was true, the cone was drawn in when I connected the battery. Once I reversed the battery polarity, connecting the - lead to the + speaker terminal the cone was produced outward. For comparison, I connected the battery to the woofers I removed and found they behaves as expected, the cone moved outward when the + terminal was connected to the + speaker terminal. I performed this test with a pioneer woofer and it behaved the same way. I just wonder if this polarity difference might affect phasing interaction between the drivers. Having said that, when the replacement drivers were still in place the T3's still sounded like something was missing.

My other thought is perhaps the crossover networks in the speakers may have issues. I have not touched them so maybe something is going on there.

Thoughts?



JBL100T3 with original JBL woofer re-installed.



Replacement woofer front view.


Replacement woofer rear view.

 

[FB night]

 

[richiem46]

I attached the 1.5V battery to the input terminals on T3's + to the red and whe woofer cone moves out. In looking at the schematic above that makes sense as the Negative input terminal goes to the Positive terminal on the woofer and vice-versa so the woofer cone moves out. As before, when I attached the battery directly to the woofer with the positive terminal of the battery connected to the positive terminal of the woofer the woofer cone moves inward.

I guess the question is wether the woofer was deliberately built this way or not. If it was not then should the connections to the woofer be reversed?

I confirmed that the speaker terminals on my T3's match the configuration of the T3 in the picture above.

I think I am confused........

 

[toddalin]

I think I am confused........

How to Understand JBL Reverse Polarity - The Speaker Exchange

 

[richiem46]

How to Understand JBL Reverse Polarity - The Speaker Exchange

Thanks! I see the 2214H is on the negative list which makes things make sense now. When I had the replacement woofers were positive so when they were installed they were wired backwards then. Not sure how that would have affected the overall sound as both woofers were installed backwards. When I install the replacement woofers in the T3's I have in Florida I will wire them backwards to match the electrical orientation of the original JBL woofers.

 

[ernieS]

I asked the seller if he had the original woofers but he said he had bought them with the substitute woofers already installed. I'll bet the originals need to be re-foamed and were discarded.......sniff sniff........

I have played the L100T3's for several days now with several different amplifiers, tube and solid-state and I have to say that they really sound great, the bass is full but not overwhelming, they really capture the sublty in the acoustic bass on some of the jazz pieces I listed to. For the $800 I paid for them I am very pleased.

I have seen several pairs of the original JBL woofers on the auction site, the going rate seems to be $700 for a pair. I will leave things as they are or I may purchase the original woofers for the L36's to see how the originals sound in them and if they substantially improne their sound punder splurging for the originals for the L100T3's....

The 2214 will be hard to come by, but will drastically outclass any other brand. Their true full range. The L80t isn’t bad as well.

 

[richiem46]

The 2214 will be hard to come by, but will drastically outclass any other brand. Their true full range. The L80t isn’t bad as well.

Fortunately I have the 2214 woofers that my wife's cousin brought up from Florida. I had re-foamed one of them and now have re-foamed the other one since I had it apart to check on the crossover wiring. Here is a picture of the re-foamed woofer. I will re-install it in the T3 today and then have a listen again to see if my impression of the overall sound of the T3's are.

 

[grey]

The 2214H is one of my favorite woofers. I didn't give the L100t3 the time and setup that it deserved, but it was much preferred over the original L100 that I had previously owned.

The surrounds from looneytune2001 on ebay was an exact match for the JBL material on several other woofers.

 

[richiem46]

I was not sure where to publish the following information but I decided to place it in the speakers forum as the L100T3's are the common element.

Over the last several years I have restored quite a few receivers/amplifiers. I learned a lot from my own research and from the help of many others here on Audiokarma. I do not consider myself an audiophile but can hear differences in how different equipment/speaker combinations sound with different source material. Three components I restored particularly impressed me. On the amplifier side, I have a Rotel RA-1412 that I completely restored and a Sansui AU-919 that I also restored. On the speaker side, I obtained a nice pair of JBL L100T3 speakers, which originally had replacement woofers, but by a bit of good luck, I was able to replace with the original JBL woofers, which I re-foamed.

The restoration threads for these components are listed below:

JBL 100T3: (this thread)

https://audiokarma.org/forums/threa...-l100t3-speakers.1091304/page-2#post-18416856

Sansui AU-919

https://audiokarma.org/forums/threads/beginning-my-sansui-au-919-restoration.1096296/

Rotel RA-1412

https://audiokarma.org/forums/threads/rotel-ra-1412-restoration-project.1020229/

 

[richiem46]

I used the Rotel here in Michigan to listen to vinyl with a pair of JBL E100 speakers in our living room. The E100 speakers are nice but they do not draw raves from what I have read, particularly in their mid-range response. My plan is to replace the E100’s with the L100T3’s at some point. What I am trying to determine with my listening test is which amplifier I intend to use going forward to drive the L100T3’s in our living room.

I conducted my listening testing in our garage here in Michigan as it was the most expedient and least disruptive place to perform the initial testing. Not optimal I know, but a good place to start as everything was physically there. For an audio source I used a Schitt Modi DAC connected to an IPAD with the Apple camera adapter connected to the "AUX" input of the amps. The source files on the IPAD with a few exceptions that I downloaded from Apple music, I ripped from CD’s using DBpoweramp in Apple lossless format.

Here is a picture of the physical setup:



Here are the two test subjects:

 

[richiem46]

Some personal background, I wear hearing aids to boost the high frequencies that us seniors have problems hearing. I disabled the noise reduction feature as it interfered with music listening by effectively turning down the volume of the hearing aids when exposed to loud noises. A nice feature normally but not so nice when listening to music.

I listened to music using the AU-919 wearing my hearing aids for an hour or so and was pleased with the overall sound but occasionally it could be a bit fatiguing. I turned everything off and went inside for the evening. The next day I went back out to the garage, turned everything on, and listened. I then realized that I was not wearing my hearing aids. Rather than getting them, I turned up the treble on the AU-919 to compensate for the boost the aids normally provided.

I gave myself a bit of time to mentally adjust to this setup and found that I preferred the sound of the system this way. My hearing aids use a rubberized membrane to center their speakers in my ear canal. I am assuming that their presence affects all frequencies to a degree and that without them being in place the music sounded more natural to me. I am curious what other hearing aid users have experienced when listening to music.

After listening to the AU-919 for another hour, I substituted the Rotel RA-1412 into the system and started to listen. Initially I was disappointed with the Rotel, it sounded somewhat flat, especially in the high end. I adjusted the Treble level a bit which helped a little initially. I let the Rotel play for a bit and after about 10 minutes, I started to think, “hey, this thing sounds pretty good”. The RA-1412’s sound was very different from the AU-919, much warmer, more “tubey” I guess you could say. After listening off and on for several hours I really liked the sound of the Rotel, but then again, I really liked the sound of the AU-919.

I am not sure what conclusion I can draw from my listening experience. Perhaps it is that neither unit is better than the other, just different.

I am in the process of restoring a Sansui AU-719, which has some of the advanced circuitry that the AU-919 does but retains the standard tone controls and the loudness switch. I have restored the power/protection board and the two driver boards and it sounds great. I still have to restore the tone and pre-amp boards at which point I will give it a listen in the same configuration and see how it compares to the AU-919 and RA-1412.