i posted this on diy.com but never got any feedback,so im posting here as well has im desperate to find out why my build is sounding so bad....
i know theres alot been said regarding the jx92 and teds site transmission line enclosurer but im trying to find out where ive screwed up as i find the sound quality quite a dis-appointment.
firstly the jx92 i have are the earlier versions not the s models,i state that incase that has any bearing on my sound quality.
i built the enclosures as advised on the site,made from 18mm mdf complete with the foam behind the driver.
when i first played them i was impressed by the bass extension(i had been using them in 8litre sealed enclosures before that) but then the chinks began to show...for me this is ..one hell of a over hang,boom or resonance,a hollowness around the mid bass area,also find the bass abit lazy sounding which tends to slow the music down and lacks tight defenition.
other then those points the knock on effect is those effects cloud the glorious mid range that i know the jordans do so well!
anyone out there with in depth experience with this enclosure and would share there hornest views regarding the sound quality they go from theres,any solutions ,fixes or ideas where i screwed up?
another point i must make is i use 845se valve amps(20watts) could the speakers be showing up there limitions? (they sounded really good with the sealed 8litre enclosures) volume isnt a issue,i never go pass 10 oclock on the pre-amp,believe me,thats more then load enough in my room!
on another note my amps have 4 and 8 ohm taps,which one do you think it sould be set on for this driver!.
sorry for the long post,im just gutted that my hard work has ended in such dis-appoint for me,i cant imagine mjs new speakers and the essences sounding like this otherwiose they wouldnt be getting the good reviews!
if anyone has a alteritive enclosure that would suit this older driver and give me lovely tight deepish bass with that open mid range and treble...i would be very intrested!
The bass response sounds odd as the Konus (a very similar design) is supposed to be a very fast sounding enclosure. Couple of suggestions - someone else on the forum recommends stuffing the very end of the pipe. Start with a minimal amount and add to see what it does. You could also try stuffing the cavity. The Jordan website just shows a piece of foam behind the driver - adding something like long fibre wool fibre or similar may help.
How does it sound if you completely block the port?
Ref the amp, I'd have thought the 8 ohm setting would be okay but others here with more experience of tube amps should be able to advise.
Hope you get this sorted. I've heard the current JX92 in this cabinet and thought it sounded ok (although not as good as GM's MLTL cabinet for bass extension).
If you could provide some additional info, it would be of help:
- What are your room dimensions ?
- Where did you locate the speakers in your room ?
- Is the booming always around the same frequency ?
- Are the JX92 drivers well broken-in ? I suppose yes, as you tell you have used them in 8 liter closed cabs, but how much time ?
- Do you feel the walls of the TL vibrate ? You could have booming just due to the TL "singing". If yes, then perhaps you should add bracing to the enclosure.
The 8 ohm tap in the amp is the right one, IMO. (Nice amp, an 845 SE, BTW).
OTOH, if you don't get it to work as you want, you can always try Tom's (TomekZ) VTL or perhaps the PAWO.
Stay cool, with a little patience you will get yout TLs working as intended, but don't let to take into account that what others like is perhaps what you abhor... It's a matter of taste...
thanks for getting back to me,moreso with your surgestions.
my room is a funny shape,one end is 8 foot wide,and that end is where the speakers are,toed in 35 degs as recommended and in each corner as far as they will go!
the length of the room is about 25feet,half way along opening up to about 12ft wide if that makes sense.
so my listerning area that i use is the 8 foot width bit which is about 10 foot length,hope you can understand that as ive lost myself there!
i tried collins idea about blocking the port completely...and that was bad news!
i tried stuffing the exit port also but found that sucked alot of the life out of the sound,i then did as collin also surgested and put some stuffing in behind the driver where the foam is and this has seemed to taken the edge off the hollowness,overhang,resonance,but its still there,and the attack to the bass seems very soft!
ghpicard,these drivers are well and truely run in,had them afew yrs now and they have had pretty constant use in that time.
it does seem to be around the same area,in the mid bass domain,adds weight to male voice(a mild barry white effect) and the bass notes just overhang,smearing it rather then stop/start/fade away quickly....sorry i realise my discription must be making it nigh on impossible to diagnose.
i did wonder if it was booming(hey that does discribe my problem pretty well) because of the cabinet,i want to like this design,and lets face it theres plenty of commerical designs of this out there with glowing reviews...so it must be my end,and if i knew for sure it was just the cabinet giving me the greif then i would go out and build a better one out of ply etc,just dont want to waste time and money on that route it it will never give me the sound i want...thats why i was intrested in peoples views regarding this designs sound!
i havent given up,or want to just not sure how to sort,adjust,mod it to suit me.
when they was in sealed 8litre enclosure the mids and highs shone because the bass wasnt massive and clouded the sound,now i have impessive extension,but the booming or whatever it is is masking the glory that the mid,highs are capable of!
thanks for your help guys
Well, the VTL is a nice design and it shouldn't give you so much problems. You describe a response peak in the midbass, and that could have several causes.
Did you try moving the enclosures to other positions in the room ? Corner loading augments much the bass response and what you perceive as boominess couldd be just that you are exciting some room mode.
You could try moving the TLs at least one meter away from each of the walls (back and side) and see if the boominess goes away. Don't worry about toe-in for now
Cheers, and report back !
P.S.: BTW, I'm supposing you used this drivers in the sealed cabs with the same amps, right ? Not that would affect much, but amps do oscillate sometimes
Last edited by ghpicard (2005-11-24 20:40:21)
It does sound like a line resonance is occuring. If you are willing to venture into the cabinet again, you could try some light stuffing into the first line, as far as you can reach.
It's a bit puzzling because the Konus doesn't use any stuffing (I don't even think it has any in the cavity, which is another tweak you could try). I'm also not sure what the tech spec differences are between the two drivers (JX92 and JX92S, current version). From memory, listening to the old 92 vs the new, the old was more restrained in the treble, so bass performance in a TL shouldn't alter that much.
PS Looking at your room size and positioning, try one speaker in your normal sitting position (ie where you listen) and then move round the room and see if the resonance changes. That may give you some clues to whether it's room-based and, if so, where to position best. Corners may not be the ideal situation. FWIW, my room is 20 by 10 and I listen with my 92 MLTLs against the long wall. (There's an old adage that the best acoustic place for speakers is where they do the most visual damage to a room!)
i thought it might be room postioning,so i dragged them right into the room to see,but the peak,boomyness was still there.
i never had this problem with the enclosed design,also the sound seems loader with the vtl design or the sealed design so in theroy im pushing the amps even less with this.
im going to try to get hold of a solid state amp to try,just so i can see how much of a part the amps play with this problem.
the trouble there is i really need monoblocks or two exact intergrateds otherwise i will have to use different speaker cables and that will effect my results,conclusions....oh the joys of diy....fun and frustrating...bit like the wife really!
would there be a marked improvement soundwise if i went ahead and built new enclosures out of ply or do you guys think there wouldnt be much in it,i so like the look,design and so want to get this sounding the way i like...
all the best
Most people seem to prefer ply as it is stiffer and lighter, but the VTL design is so well braced internally I wouldn't have thought it would make much difference. The only two panels which have much chance of resonating are the front and back of the cavity. You could try a couple of G-clamps on one enclosure to see if that braces them and makes a difference. The Konus design is mdf but one or two posts on here have described big differences from the same cabinet when built from mdf and ply.
In theory, the line should be tuned to about 45Hz and the cavity should decouple the driver's output from the line above 90-100Hz. Do you have access to any test tones to see where the resonance lies? (I made a CD of test tones using SoundEdit on my Mac; there should be plenty of programs out there to do the same with a PC.)
Another idea (you'll be getting a good workout from all this), I wonder if raising the height of the enclosures would help? And what sort of floor are they on? Try them on different surfaces/heights and see what happens. It may be that fitting spikes would help sort the problem.
ive had theses speakers just about everyway,postion possible now in my room,firing across and length ways into the room,on spikes,on concrete(which is what the floor is) still to no avail,im still doing the stuffing thing but still havent found that magic formular yet.
the clamps was a good idea collin,unforntally i dont have any big enough to clamp the speakers to good effect!
maybe its just my amps,if it is then ill be looking at another enclosure as im not about to ditch them,its taken me years to get to them and im in no rush to to go back to solid state!
ive been in touch with mj acoustics asking about there versions there realeasing(well they look similar) but its been 2days and no reply,hoping i might be able to get a listern,see if they suffer what im hearing or weather its just my iffy build quality or something,would love to hear the kronus to for the same reason but theres no chance of that,thats the trouble living this far west nothings close...real hifi here to most is dixons,currys...thank god for the internet and people,forums like your good selfs!
all the best
Dixons and currys, eh? I hadn't realised you were in the UK. Where are you based?
I may have the specs for the older JX92 driver. I'll search around my files and if I find them I'll post a comparison in case anyone here has some insight to how the altered specs may change the sound in this enclosure.
Potential red herring but what cable are you using? Could it be a damping factor effect?
Another cheap way to try to damp resonances: put a sandbag (as big as you can get) over the top of the enclosure. Also, if you get to put the enclosure horizontal (with the driver firing upwards) and you have the resonance, then put the sandbag on the enclosure and move it around and see if the resonance changes. Same effect of the G-clamp but distributed and not resonant in itself.
The same ubiquitous sandbag *under* the feet of the enclosure might help too, and also will decouple a little the enclosure from the floor.
And I asked about the amps just in case what's wrong is the amps themselves. Did you try the amps wit a different speakers ? Or are the amps the very same you were using when the Jordans were in the sealed cabs ?
sorry for delay,keep flicking thro different forums,i thought i set this up so i would get email notification,obviously not!
the sand bag idea is a good one,saying that the wife didnt think so,and im at the stage now where ive amused myself to death with them trying this and that so gearing myself up for anew project(8ltr sealed enclosure for the jx92 like i had before only better made this time,and my amps sounded good with this design, and the main bass duties will be handled by a jx125 in a 35 ltr sealed enclosure but powered by some solid state amps)
i really want the jx92s to get down to around 80hz in the 8 ltrs,dont know if they will,and the jx125s take over from there...not sure of inductor valve to start with that will give me that point.
ted mentions 3ltr cab and 112 hz cross point with the jx125...
but ive spent time playing with in car stereo gear and have found that directional infomation is still present around 90-100 hz,while under that its been less so....hence the reason for my 80hz extensiopn theroy!
the cable i use is monoliths 2.2 flat copper cable(abit like gortz and max townsend design) it cant be used with any old amp,but it works with the gear you have then i dont think it can be beaten!
all the best
Based on published specs, max-flat sealed enclosure is -3dB right around 80Hz, so it could work.
IIRC using JX125 as subwoofer doesn't really use its full potential, but hey.
thanks for that info,regarding not using the full potental on the jx125s,i realise thats the case,but i would rather get the max out of the jx92s in the area that i hold dear...the mid range!
yrs ago i had a linear array(jx53s) mated to the jx125s so i do knowthey can do so much more.,but that setup would no longer be idea with my single ended valve amps.
all the best
after building the Jordan TML design I have a similar problem as you had. I try to explain it in my German English. The sound is like it is pressed together. The air in the sound is missing. One can notice the potential in the sound. But at the end the sound is quite disappointing. I am also wondering what I did wrong. In a German speaker building journal (K+T) the Jordan VTL became an excellent review. Also hifi-sound, the German distributor, told me that people are very enthusiastic with this loudspeaker.
Smithi, did you make some more experiments to find the reason for the bad sounding loudspeaker.
I would highly appreciate any feedback regarding the Jordan TML design.
I recently built a pair of the 48" TL's in the triangular design for a buddy, but was hesitant to post impressions for a couple of reasons.
The cabinets were 3/4" baltic birch ply, no additional cross bracing; a 1/2" layer of cotton felt on all 3 walls to about 3" below the drivers and on the bottom plate below the port tube. A wild ass guess at BAF damping material in the top section, held in place with stapled strips of cotton cloth.
First caveat is that this pair was at least slightly damaged and repaired by the owner, and absent another pair for comparison, their operating condition is questionable.
Secondly, a preference for another flavor of (much lower cost) driver will be come immediately apparent - feel free to discount these comments accordingly.
INITIAL impression was well defined and articulate bass, extending lower than any of the Fostex FE126 horn or FE127 MLTL designs; but lacking a degree of textural nuance on percussion and acoustic guitars as well as exhibiting a recessed midrange and collapsed depth/width of soundstage compared to either of the Fostex designs. A variety of toe-in angles from straight on to the full 30dg off axis were experimented.
Most notably fatiguing was the reduction in perceived dynamic contrast vis a vis the Fostex -whether driven by an 8W or so class A biased PP EL84 or the 15W mini-aleph, the Jordans felt compressed, particularly at the top end of their dynamic range - never imparting quite the same sense of realism as the .......
Of course YMMV, etc etc
I have the Jordan s's in 8 liter ceramic kinda egg shaped pots well damped and they sound better than any other enclosure i have ever heard . I have A-B'ed them with Teds TML and the sound difference was as you describe , altho moreso as the pots are so incredibly clean . I highly recomend that you do NOT use a passive speaker level XO between the woof and the 92'S . ive never heard a good one on these speakers. They are so clean and open that most things affect them . I use a passive line level xo and bi amp with discrete amps. Plate amps also work quite well on the bass and have EQ and XO built in if that is desired . Useing 2 woofers, 1 on each side and XO @ 100 HZ. the higher XO makes them sound more open and stress free, and will play incredibly loud and clean. Asking the tiny 3-3/8" dia cone to produce frequencys below 100 HZ inevitively affects the mids no matter horn or whatever. Teds solution, is the problem in this respect, as the extremely thin cone reguratates sounds from behind it . A lot of what you hear fron the TL comes from this cause . Damping the enclosure volume and the area behind the cone on the pots was a time consuming job to get right, and is worse in the TL or rectangular boxs i first used.
These have been running in my system for over 4 years and they delight as much today as they first did. I have no intention of useing any thing else
Thor, what part of the country you located, am curious to hear your system.
I have aims on a very similar system, though am tempted to push xover freq to 150Hz or so to give the Jordans a little more excursion relief/overhead.
HI erickson im in the US of A , in Arizona, Bullhead city, in the great Mojave desert 2 miles from the Colorado river:) If you ever get this way id be glad to share . if you push XO up to 150, 2 woofers or subs are mandatory. I have mine set up near field Regards Thor:)
if you push XO up to 150, 2 woofers or subs are mandatory.
Certainly, that would be the plan. I would almost surely use active xover (L-R 4th order, 24dB/oct).
I've done some back-of-hand calcs, stereo subs crossed at 150Hz could easily be placed less than a wavelength from mains. Also, all bass freqs would be "floor loaded" under the traditional rule of 1/8 wavelength, if bass drivers placed low. Plus, I recall some "rule" saying a woofer shouldn't cover more than three octaves (where did I read this?) and 20-150 is just under that limit.
I also used Linkwitz's SPL calculator on the Jordan's surface area, they appear quite capable of giving 105dB at 150Hz well within xmax, when you consider a 6dB boundary (wall) lift and a 6dB contribution from the bass driver. So this seems to put it in the realm of "realistic" SPL production for a reasonably sized living room.
I'll probably be buying a pair of Jordans later this year, trying them out in one of GM's TL designs, before going for the whole-hog thing.
BTW what kind of amp you using on the Jordans?
Finally, the wife wants to visit Grand Canyon this year, a side trip to Bullhead City may very well be a realistic option if schedules allow. No deets on dates yet.
Heard very nice things about your setup from rich drysdale. When/where you meet him?
Hi again about subs and pots nearfield: my pots are 48 " from my ears , with the speakers 1' from front wall [ which is covered by a huge berber carpeting wall to wall]. They are 58" apart on my desk, The subs are on the floor, flanking my chair, 1 on each side , and center of sub drivers are also 48" from each ear and 34" in front of the pots . like this:)
* [me] *
Im kinda sitting in the middle of a time aigned line array lol:) image is huge , pinpoint with in that huge space extende 4 ft behind and outboard of the speakers. The incredibly complex and harmonically rich Carmina Burhana creshendos hit a clean 103 db
Im useing a good mid fi Onkyo ss on the 92s'es and a fine old rebuilt Sony ES ss amp on the HSU subs. By the time you get here I may have the Curico modded Dyna ST 70 [that I got from Bruce unmodified] on line on the pots . god, that amp sounds transparent!!!!!! Im stunned by it !
I know Rich thru my good friend Bruce Edgar. I hosted 1 of Bruces horn club monthly meetings at my home in Orange Co. just before i came here . Thats where Bruce, Steeve Shell, Rich Drysdale and the other hornies all heard them [with the SS amps:)
I dont prefer TL's but GM's is 1 of the best. The triangular one looks interesting too [ I forget who designed it ]
The triangular one was a combined design - GM designed the 48" MLTL, I asked if it would work well as a triangle cross-section, Bruce (apea) built several variations with suggestions from GM and the triangle layout went onto the Jordan site (with GM's approval) at
They do sound good - the triangle shape gets rid of any boxiness to the sound and makes damping easier. Not as deep (front to back) as your pots though.