Hi All,
I'm thinking of building a Jordan JX92 bookshelf Transmission line speakers. I want them to go down to about 40Hz flat. Something similar to PMC TB2 (but single driver).
Can you help?
Either point me to already proven design, or let me know what tools can I use to help me design my own enclosure?
I am looking towards a bookshelf design due to rigidity of the cabinet, amount of material required and the fact that I already have made some nice stands that I would like to use.
Thanks in advance for your hepl.
P.S.
Here is a pic of my stands:
I'm thinking of building a Jordan JX92 bookshelf Transmission line speakers. I want them to go down to about 40Hz flat. Something similar to PMC TB2 (but single driver).
Can you help?
Either point me to already proven design, or let me know what tools can I use to help me design my own enclosure?
I am looking towards a bookshelf design due to rigidity of the cabinet, amount of material required and the fact that I already have made some nice stands that I would like to use.
Thanks in advance for your hepl.
P.S.
Here is a pic of my stands:
Attachments
Colin said:
No time to do a search right now, but it is hear somewhere.
http://www.diyaudio.com/forums/search.php?s=
dave
How about a different design for a bookshelf using a jordan JX92? I still want it to go down as low as possible while maintaining reasonable size (let's say 6l). Has anyone done the bass reflex 6 liters design described on the jordan website? I though that such design, maybe with a super tweeder, might be promissing.
Cheers,
Rafal
Cheers,
Rafal
I think you could probably build a bookshelf TL.
I built the HiFi world KLS5 design a few years ago:
http://www.geocities.com/CapeCanaveral/Hangar/2091/kls5ing.html
They sound fantastic and are almost bookshelf sized, sitting on a pair of 20" stands.
They use the Audax HM170Z0 drive unit which is bigger than the Jordan unit so I think you could use the same line length but make the design a bit smaller.
Certainly I think you could make them less tall as the line would not have to start off so wide but you might instead be able to decrease the depth and add an extra fold to the line so the open end is forward firing.
I built the HiFi world KLS5 design a few years ago:
http://www.geocities.com/CapeCanaveral/Hangar/2091/kls5ing.html
They sound fantastic and are almost bookshelf sized, sitting on a pair of 20" stands.
They use the Audax HM170Z0 drive unit which is bigger than the Jordan unit so I think you could use the same line length but make the design a bit smaller.
Certainly I think you could make them less tall as the line would not have to start off so wide but you might instead be able to decrease the depth and add an extra fold to the line so the open end is forward firing.
Colin said:
I didn't build them, and am still using the smaller bass reflex cabinets, which I am quite happy with. I have major concerns with the excursion of the driver in a larger cabinet being too great.
Don't forget about Sheldon's TL:
http://www.quadesl.com/tidytl.shtml
which is completed, and he is happy with it.
--
Brian
I've listened to Brian's ported jordan speakers, and I can definitely say that I was impressed. While the bass doesn't extend much lower than 60Hz, the frequencies above 60Hz certainly make themselves known, actually to the point that they should be placed a couple of feet forward from the wall to avoid being excessively bass-heavy. Even though there was a lot more bass than I expected from such a small driver, It never sounded boomy or poorly-defined, even at higher volumes. They are extremely detailed and responsive throughout their entire frequency range and have great highs, considering the size of the driver.
Overall, i think getting better sound out of the drivers would be very difficult, and trying to push the F3 down to 40Hz would cause extremely poor frequency response. It might be possible to get a relatively smooth repsonse from the jx92's a little lower, with a well-designed TL, but it would probably require a very long, tapered line, and trying to fold it into a bookshelf cabinet would be impossible. Looking at Sheldon's TL, even though he says they sound better than they look in the charts, the TL provides no real bass extension over the small, ported box, and it has some very nasty nulls in the response. Even though I like TL's, and I certainly can't say anything bad about this driver, I just don't think it would benefit much from a TL enclosure, and if you want bass lower than ~60Hz, I'd recommend you consider a different driver.
Overall, i think getting better sound out of the drivers would be very difficult, and trying to push the F3 down to 40Hz would cause extremely poor frequency response. It might be possible to get a relatively smooth repsonse from the jx92's a little lower, with a well-designed TL, but it would probably require a very long, tapered line, and trying to fold it into a bookshelf cabinet would be impossible. Looking at Sheldon's TL, even though he says they sound better than they look in the charts, the TL provides no real bass extension over the small, ported box, and it has some very nasty nulls in the response. Even though I like TL's, and I certainly can't say anything bad about this driver, I just don't think it would benefit much from a TL enclosure, and if you want bass lower than ~60Hz, I'd recommend you consider a different driver.
BrianGT said:
tpenguin said:
That is exactly what I decided after thinking about it for a while.
I also had BSC on my speakers 4 ohm resistor in parallel with a 1.5mH inductor, so they can get boomy if you put them too close to the wall, or in too small of a room. If I bypass the BSC, they sound much better in a small room, but thin in a larger room.
The design is based on Jim Griffin's speakers that I heard over a year ago at the DIYATL2002 event.
--
Brian
Thanks for all your suggestions.
Brian,
What driver did you finally decide on?
Backing up a bit...
What I am ultimately trying to do is improve upon my current speakers which are Tannoy System 800 Active - professional monitors. The rason I am leaning towards asingle driver is to avoid a passive crossover. Basically what I want to improve is percieved realism of the performance. I have heard some nice Linn active setups and that would be ultimate but the bank sys NO.
Can you suggest an approach, hopefully a single/wide range, that would present a major improvement over my existing setup (and not cost me an arm and a leg)?
Cheers,
Rafal
Brian,
What driver did you finally decide on?
Backing up a bit...
What I am ultimately trying to do is improve upon my current speakers which are Tannoy System 800 Active - professional monitors. The rason I am leaning towards asingle driver is to avoid a passive crossover. Basically what I want to improve is percieved realism of the performance. I have heard some nice Linn active setups and that would be ultimate but the bank sys NO.
Can you suggest an approach, hopefully a single/wide range, that would present a major improvement over my existing setup (and not cost me an arm and a leg)?
Cheers,
Rafal
BrianGT said:
That is exactly what I decided after thinking about it for a while.
I also had BSC on my speakers 4 ohm resistor in parallel with a 1.5mH inductor, so they can get boomy if you put them too close to the wall, or in too small of a room. If I bypass the BSC, they sound much better in a small room, but thin in a larger room.
The design is based on Jim Griffin's speakers that I heard over a year ago at the DIYATL2002 event.
--
Brian
Maybe for the best overall sound you should decrease the BSC by about 2dB?
Another option might be the Jordan VTL, on the Jordan website. It isn't a bookshelf design but the commercial version, the Konus Essence, gets very good reviews and is reported to extend the driver to around 50Hz. I believe there are a few people on this and the fullrange forum who have built this design.
Colin
Jordan VTL transmission line
Konus Essence
Colin
Jordan VTL transmission line
Konus Essence
I'm currently building some standmount speakers using JX92S's, which I'll post details & measurements of when I've finished fiddling. They're not exactly "bookshelf", at about 15 litres, but roughly the same size as the speakers in your pic. I'm planning on a bass reflex, not TL design, and I'm aiming for a smooth rolloff and good transient response, rather than a boomy highly-tuned one.
A number of reports suggest the driver needs quite a bit of break-in to achieve "full" bass response. This might have some truth to it - out of the box the free-air resonance was about 55Hz, but after an hour of playing LF sweep tones through it, it had dropped by a few Hz.
More later...
Cheers
IH
A number of reports suggest the driver needs quite a bit of break-in to achieve "full" bass response. This might have some truth to it - out of the box the free-air resonance was about 55Hz, but after an hour of playing LF sweep tones through it, it had dropped by a few Hz.
More later...
Cheers
IH
Thank you all for your suggestions.
I have considered making the floor standing VTL with Jordan 92's. I even considered pairing it up with a subwoofer. I may still go down that path, but there is something to be said for a beautifully executed bookshelf (like a B&W nautilus 805 Signature).
Ian,
I would be very interested to sread more about your project. can you e-mail me once you have it done?
I have considered making the floor standing VTL with Jordan 92's. I even considered pairing it up with a subwoofer. I may still go down that path, but there is something to be said for a beautifully executed bookshelf (like a B&W nautilus 805 Signature).
Ian,
I would be very interested to sread more about your project. can you e-mail me once you have it done?
I built 7 litre minimonitors using Jim Griifins design, but using an 2x12mm MDF + 2mm lead sandwich. I put the port on the front and use them without BSC against a brick wall. I also exchanged the foam for a Deflex panel on the rear wall and a ring on the rear of thje driver. I thought this gave more sense of air around the instruments.
The mid is superb but they need a subwoofer. I also found the top a bit harsh especially on orchestral strings. and am in the process of adding Fountek JP3 ribbons, which make a big difference in my first lash-up. I need to make new front baffles now.
I'm crossing at 6k with a first order, but am thinking of going up to 7.5k with a 3rd order, following the xover at
http://www.d-s-t.com.au/Ventura/RibbonTweeter.htm
The mid is superb but they need a subwoofer. I also found the top a bit harsh especially on orchestral strings. and am in the process of adding Fountek JP3 ribbons, which make a big difference in my first lash-up. I need to make new front baffles now.
I'm crossing at 6k with a first order, but am thinking of going up to 7.5k with a 3rd order, following the xover at
http://www.d-s-t.com.au/Ventura/RibbonTweeter.htm
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