Bigdnfay1 Posted January 21, 2012 Share Posted January 21, 2012 If you were going to port a jub cabinet, how large would the ports need to be? round or square? Big D Quote Link to comment Share on other sites More sharing options...
Guest Anonymous Posted January 22, 2012 Share Posted January 22, 2012 I have no clue, im sure others will chime in. What MF/HF are you using on those Jubilee Bins there? Quote Link to comment Share on other sites More sharing options...
Moderators dtel Posted January 22, 2012 Moderators Share Posted January 22, 2012 Confused also, Being a folded horn, I would think a port would not work or at least be extremely tricky to get right ? Quote Link to comment Share on other sites More sharing options...
Coytee Posted January 22, 2012 Share Posted January 22, 2012 I would think a port would not work or at least be extremely tricky to get right ? Isn't a passive radiator similar to a port but becuse of the passive radiator, it allows you to make the port bigger (smaller?) and perhaps derive some other benefits? Big....surely you have seen W.C.'s thread on building the Jube-Clone with passive? http://forums.klipsch.com/forums/t/153826.aspx There's the link if you haven't. I don't know if it will help. This stuff is over my pay grade. Quote Link to comment Share on other sites More sharing options...
PrestonTom Posted January 22, 2012 Share Posted January 22, 2012 It's a good question. The closest that someone has come to venting the Jub is the drone version that was built at the factory. Appearently, it still required some fine-tuning, but the project was ultimately dropped or put on the back burner. There is a DIY version being built right now and is documented in a lengthy thread. It is an ambitious project and a very interesting one. It is not yet complete and it is unclear what headaches will be encountered on the way. The trick is that it is not simply venting the back volume with a drone. Rather the drone itself is also horn loaded. So there are some uncharted waters here. Quote Link to comment Share on other sites More sharing options...
Guest " " Posted January 22, 2012 Share Posted January 22, 2012 Confused also, Being a folded horn, I would think a port would not work or at least be extremely tricky to get right ? I would think of it as the concept used to port the LaScala's. The port would go on the botom or the top. Tuned to about 40hz. All that is needed is the chamber volume of the jubilees and use one of the online calculators to tune the port to about 40hz. you could probally put the port right into the top woofer access panel Quote Link to comment Share on other sites More sharing options...
Moderators dtel Posted January 22, 2012 Moderators Share Posted January 22, 2012 The trick is that it is not simply venting the back volume with a drone. Rather the drone itself is also horn loaded. So there are some uncharted waters here. Thank you, that's what was throwing me off. When I think of porting I think the way a normal speaker is ported which is different than porting the beginning of a folded horn . I thought a drone or passive radiator was like halfway between ported and sealed and shared some of both benefits. Quote Link to comment Share on other sites More sharing options...
Moderators dtel Posted January 22, 2012 Moderators Share Posted January 22, 2012 Confused also, Being a folded horn, I would think a port would not work or at least be extremely tricky to get right ? I would think of it as the concept used to port the LaScala's. The port would go on the botom or the top. Tuned to about 40hz. All that is needed is the chamber volume of the jubilees and use one of the online calculators to tune the port to about 40hz. you could probally put the port right into the top woofer access panel I see what your saying now, changing by size of a back chamber or porting it, or PR/drone to affect what is sent through the folded horn section. I would think this would be very tricky to get some benefit from this without affecting what happens in the original design of the horn. It is interesting, you have to realize that back space was very limited in the original designs because so much space was taken up for the folded horn to keep the overall speaker size that was usable. Quote Link to comment Share on other sites More sharing options...
colterphoto1 Posted January 22, 2012 Share Posted January 22, 2012 the back box is really to make a compression driver out of it. I don't think you'd want to port it, there would be huge time alignment and phase difficulties. It's all about phase you know. Quote Link to comment Share on other sites More sharing options...
Guest " " Posted January 22, 2012 Share Posted January 22, 2012 It is interesting, you have to realize that back space was very limited in the original designs because so much space was taken up for the folded horn to keep the overall speaker size that was usable. yep...even more interesting is that if you look at the top view build plans of the jubilee, you will see a lascala dog house scaled down for a 12" driver. theres an extra fold in the jub cab. so the same port add on would work if done well...but as in the porting of the lascala...could cause boomynessif not done well. Quote Link to comment Share on other sites More sharing options...
PrestonTom Posted January 22, 2012 Share Posted January 22, 2012 Confused also, Being a folded horn, I would think a port would not work or at least be extremely tricky to get right ? I would think of it as the concept used to port the LaScala's. The port would go on the botom or the top. Tuned to about 40hz. All that is needed is the chamber volume of the jubilees and use one of the online calculators to tune the port to about 40hz. you could probally put the port right into the top woofer access panel SF: with all due respect I think it will be more complicated than this. Even if you do something like DJK suggested for the La Scala, you will still need to worry about woofer excursion and the fact that a vented system may only change the low frequency extension by 1/3 to 1/2 octave if you are lucky. The (horn loaded) drone version or adding a sub may be a better option. Quote Link to comment Share on other sites More sharing options...
djk Posted January 22, 2012 Share Posted January 22, 2012 "If you were going to port a jub cabinet, how large would the ports need to be?" The rear volume would need to be increased by a large amount before it could be ported. Quote Link to comment Share on other sites More sharing options...
Bigdnfay1 Posted January 22, 2012 Author Share Posted January 22, 2012 I've been following W.C.'s thread with great interest and it got me thinking about porting the jub in the usual manner. Knowing the port needs to follow the signal path, this came to mind.(sorry not to scale). So what you guys are saying it's a bad idea. Quote Link to comment Share on other sites More sharing options...
RRFL Posted January 23, 2012 Share Posted January 23, 2012 Not that I have ever watched Monty Python "but now for something completely different". I wish my replacement Jub would get to an Australian port and then be delivered to my house. What about attaching one of these to the Hatch cover on your Jub for a real Nautical touch.[] Quote Link to comment Share on other sites More sharing options...
T.H.E. Droid Posted January 23, 2012 Share Posted January 23, 2012 If you were going to port a jub cabinet, how large would the ports need to be? round or square? Big D Adding a port to a horn driver is like taking the keel out of a boat to make it lighter. The sealed driver box is a fundamental part of the design and the acoustical impedance is important to achieve high efficiency. Trying to use the back energy for more bass would likely destroy the efficiency of the horn and end up being a complicated nightmare with no benefit. Far easier to simply add a subwoofer if you want even more bass. You can then simply dial up a good sub system until your viscera turns to goo and your genitals drop off. Quote Link to comment Share on other sites More sharing options...
PrestonTom Posted January 23, 2012 Share Posted January 23, 2012 If you were going to port a jub cabinet, how large would the ports need to be? round or square? Big D Adding a port to a horn driver is like taking the keel out of a boat to make it lighter. The sealed driver box is a fundamental part of the design and the acoustical impedance is important to achieve high efficiency. Trying to use the back energy for more bass would likely destroy the efficiency of the horn and end up being a complicated nightmare with no benefit. ........ With all due respect, that is just speculation. Folks have taken a La Scala bass bin (also horn-loaded) and vented it. The bass went a bit lower and I don't think anyone measured an appreciable decrease in the cabinet's efficiency. Perhaps you know of some other data that I am unaware of. As far as increasing the back volume, this of course could be done in a similar fashion to what was done with the La Scala modification. The access panel (on the bottom) is replaced and the unit now "stands" on a riser. The cavity of the riser and back chamber are now shared. The riser also incorporates the ports and the mod is reversible. Adding a sub would be another approach. Quote Link to comment Share on other sites More sharing options...
Guest " " Posted January 23, 2012 Share Posted January 23, 2012 a vented system may only change the low frequency extension by 1/3 to 1/2 octave if you are lucky. thats exactly correct.......at best......depending where you tune it...BUT, I wouldn't do it anywhere in the horn exit path...I would do it on either the top or bottom of the cabinet.....bottom would be my choice....it wouldn't be roaring thunder...but it wouldn't be cat farts either. Quote Link to comment Share on other sites More sharing options...
RRFL Posted January 25, 2012 Share Posted January 25, 2012 If you were going to port a jub cabinet, how large would the ports need to be? round or square? Big D Adding a port to a horn driver is like taking the keel out of a boat to make it lighter. The sealed driver box is a fundamental part of the design and the acoustical impedance is important to achieve high efficiency. Trying to use the back energy for more bass would likely destroy the efficiency of the horn and end up being a complicated nightmare with no benefit. Far easier to simply add a subwoofer if you want even more bass. You can then simply dial up a good sub system until your viscera turns to goo and your genitals drop off. If you want lower bass extension from your Jubilee, I would suggest building A Tuba HT LP in the 72" x 18" x 36" full size version. Stand it vertical in the corner behind your Jub mouth down 16" to 24" above the floor. The Tuba bandwidth is 15hz - 100hz and is the same type of horn as the Jub. The other possibility is the Danley Taped Horn which is much larger however the horn design is not the same as the Jub so the transient response may be different. I'm building the Tuba as mentioned for my Jubs as the LFE for movies. Personally, I have never been 100% satisfied with mixing bas reflex or any other ported bass unit with horn loaded units. A sealed bass unit is preferred IMO but nothing touched 100% horn loaded. I developed this opinion from mixing live bands through various systems and only the 100% horn loaded system provide the essential transient response in my experience. Anything, that's ported is subdued by comparison. So I say leave your Jubs alone and build a specific purpose designed LF unit. Quote Link to comment Share on other sites More sharing options...
Recommended Posts
Join the conversation
You can post now and register later. If you have an account, sign in now to post with your account.
Note: Your post will require moderator approval before it will be visible.