Those TLX 8 are basically a slightly updated (aesthetically) version of the earlier j325 10" 3 way.
The j325 were also available as the JBL Professional "Industrial Series" as the 8325 / 8325A.
The 8325 & 8325A were used in countless movie theaters as surround/foreground sepakers for years & years.
So one should'nt underestimate the amount of attention that those speakers were subjected to.
They were built to meet the standards that movie theaters were expected to achieve (THX et-al).
Now were they JBL's best ? No not by any measure...
But they are far better than most folks give them credit for.
Built to a price point they are what they are,but that does'nt mean they sound like crap.
They sound more than acceptable when used within their stated parameters.
I should know as I currently own a pair of j325 and j350A (also owned a pair of j325A too).
The TLX tweeters in the TLX 8 are the titanium composite models no.s 011 -or- 012.
These are a cloth dome with titanium "vapor deposited" on them.
Woofers are aquaplas coated ~ cloth surround ~ stamped basket no. 310G-x.
And the mids are likely the poly cone ~ stamped basket no. 305G-x.
https://www.hifiengine.com/manual_library/jbl/tlx8.shtml
Now the TLX 18 are another variant,these had a version of their pure titanium dome tweeters in them.
The rest of the drivers were more-or-less the same as the TLX 8 IIRC.
https://www.hifiengine.com/manual_library/jbl/tlx18.shtml
These TLX were a parallel line to the LX series of speakers,with the equivalent of the TLX 18 being the 10" woofer LX-55.
The LX series had revised drivers in all postions,(410G / 405G / 026 Ti) and a bit better overall build quality.
In my research I've gotten the impression that the TLX lines were more intended for overseas distribution.
I say that as stateside they tend to be fairly uncommon vs. the j -and- LX models and the industrial series models.
That and the fact that they were available in the same time frame seems to suggest that there would've been some sorta redundancy between the various (possibly competing) lines of "entry level" speakers.
Me,I have a soft spot for these less popular JBL speaker,so were the prices reasonable,I'd likley buy both pair.
I say that as I find them quite enjoyable with the right companion gear.
JMO ~ FWIW ~ YMMV
Bret P.