Page 1 of 2 12 LastLast
Results 1 to 15 of 35

Thread: 2245h in a fireplace

Hybrid View

Previous Post Previous Post   Next Post Next Post
  1. #1
    Senior Member audiomagnate's Avatar
    Join Date
    Jan 2011
    Location
    Colorado and Georgia
    Posts
    1,022

    2245h in a fireplace

    Here we go. It works! The flue is wide open, so it's technically an IB. Fun stuff.
    Attached Images Attached Images   

  2. #2
    Senior Member
    Join Date
    Apr 2011
    Location
    Leesburg, VA
    Posts
    322
    The chimney may work as a transmission line. Good use of an unused fireplace, in any event.
    Oppo BDP-95 DCX-2496 RMX-850 Parasound A21 First Watt J2 Dayton RSS390HF-4 MTM Quads of SEAS W18E001 511Bs TAD TD-2002

  3. #3
    Senior Member
    Join Date
    Apr 2012
    Location
    Houston
    Posts
    766
    Does your flue rattle at all?

    the reason you don't hear it outside is probably because of the height. Bass is omni directional but only to a point. Your radiation is radiated out in all direction from the plane of the top of the chimney.

  4. #4
    Senior Member audiomagnate's Avatar
    Join Date
    Jan 2011
    Location
    Colorado and Georgia
    Posts
    1,022
    Quote Originally Posted by NickH View Post
    Does your flue rattle at all?

    the reason you don't hear it outside is probably because of the height. Bass is omni directional but only to a point. Your radiation is radiated out in all direction from the plane of the top of the chimney.
    I have run sweeps down to 1 Hz and there are no rattles, except the ones in the room I had to track down. I'm sure if I went up on the roof I could hear it, but from down in the yard I can't hear anything at all, even at fairly loud levels.

    To to answer a previous question, it rains a lot here but I've never seen water in the fireplace. Leaves do make it down here and I will fix that by placing a screen at the top of the chimney.

    I do plan on getting a second woofer but I'm enjoying my system immensly as it is. Oddly enough, classic rock like Steely Dan is what I'm enjoying right now, not pipe organ or dub step. It's fun hearing these albums I've heard hundreds of times - usually with great conventional subs - the IB way. You don't realize how much box sound subs put out until it's gone. I'm going to have to get my regular mains, modded L200s, down here. The only downside is I get nodes and antinodes in this rather large room, around 20 x 70 feet. My sub swarm is better in that one respect. I may have to strategically locate a conventional sub or two, at a lower than normal level, to fix that. Or I could build some more IB's and into the feed the backwaves into the unfinished part of the basement... Hmm.

  5. #5
    Senior Member 1audiohack's Avatar
    Join Date
    Jul 2007
    Location
    Las Vegas Nevada
    Posts
    3,092
    What does it sound like outside?

    Barry.
    If we knew what the hell we were doing, we wouldn't call it research would we.

  6. #6
    RIP 2021 SEAWOLF97's Avatar
    Join Date
    Jan 2006
    Location
    in "managed decline"
    Posts
    10,054
    I had an old audio book that showed how to mount drivers in closet doors for IB effects.

    and a driver outside the house coming to a horn that filled the interior wall. Pics in some old thread.
    The 50's was a great time for audio experimentation.
    Some kind of happiness is measured out in miles

  7. #7
    Senior Member
    Join Date
    Aug 2010
    Location
    Jättendal (Giant Valley), Sweden
    Posts
    763
    All you need now is recording of Santa coming down the chimeny :-)

  8. #8
    Senior Member audiomagnate's Avatar
    Join Date
    Jan 2011
    Location
    Colorado and Georgia
    Posts
    1,022
    Quote Originally Posted by fpitas View Post
    The chimney may work as a transmission line. Good use of an unused fireplace, in any event.
    What is commonly called a transmission line is actually a 1/4 wave tuned port (like an organ pipe) with sound damping materials along the tube to absorb upper frequencies. A true transmission line slowly absorbs the back wave with denser and denser materials until the wave can be transmitted into a solid material. The end of this tube, the top of the chimney, is open. The chimney has to be resonating at a frequency with a wavelength 4x its length since it's a open/closed tube, but it isn't ported back into the room, so this is functioning like as an IB, not a TL.
    Quote Originally Posted by 1audiohack View Post
    What does it sound like outside?
    Inaudible, I checked. It sounds absolutely glorious inside, and I still don't have the EQ/rolloff/subsonic filter where I want it yet, miniDSP is probably in my future, but a good parametric eq combined with an EC will work too and keep things analog and simpler. The group delay and phase plot for an IB are amazingly good, you are hearing the signal, not the box. You really need more moving area to do an IB properly (four 2245's would be about right), but this works great at moderate levels, the cleanest bass I've ever heard (my first IB) and I've been building subs since the 70's. I've got a bridged BGW 620B driving it, around 500 watts, but I don't want to push it to beyond the Xmax limit. I can't imagine going back to box subs. This really is special.Construction was extremely easy. Materials are a 31" x 49" sheet of 3/4 MDF, a roll of roofer's sealant, some fiberglass for behind the driver, screws and T nuts, and eight masonry bolts, about $60 total. The seal is tight but I don't think it's super critical because there is no pressure buildup. I did remove the damper mechanism to make the path more open and to prevent potential rattles.
    Attached Images Attached Images  

  9. #9
    Unabashed Speakerholic cosmos's Avatar
    Join Date
    May 2007
    Location
    Ohio
    Posts
    296

    Rain Concern?

    Is it possible for the driver to get wet during a storm? Not sure how your chimney is built, but it would be bad if a 2245 got wet.. or critters in the chimney?

    Dan

  10. #10
    Senior Member
    Join Date
    Apr 2011
    Location
    Leesburg, VA
    Posts
    322
    Quote Originally Posted by audiomagnate View Post
    What is commonly called a transmission line is actually a 1/4 wave tuned port (like an organ pipe) with sound damping materials along the tube to absorb upper frequencies. A true transmission line slowly absorbs the back wave with denser and denser materials until the wave can be transmitted into a solid material. The end of this tube, the top of the chimney, is open. The chimney has to be resonating at a frequency with a wavelength 4x its length since it's a open/closed tube, but it isn't ported back into the room, so this is functioning like as an IB, not a TL.Inaudible, I checked. It sounds absolutely glorious inside, and I still don't have the EQ/rolloff/subsonic filter where I want it yet, miniDSP is probably in my future, but a good parametric eq combined with an EC will work too and keep things analog and simpler. The group delay and phase plot for an IB are amazingly good, you are hearing the signal, not the box. You really need more moving area to do an IB properly (four 2245's would be about right), but this works great at moderate levels, the cleanest bass I've ever heard (my first IB) and I've been building subs since the 70's. I've got a bridged BGW 620B driving it, around 500 watts, but I don't want to push it to beyond the Xmax limit. I can't imagine going back to box subs. This really is special.Construction was extremely easy. Materials are a 31" x 49" sheet of 3/4 MDF, a roll of roofer's sealant, some fiberglass for behind the driver, screws and T nuts, and eight masonry bolts, about $60 total. The seal is tight but I don't think it's super critical because there is no pressure buildup. I did remove the damper mechanism to make the path more open and to prevent potential rattles.
    It's still a transmission line, but it may not be tuned where you want it
    Oppo BDP-95 DCX-2496 RMX-850 Parasound A21 First Watt J2 Dayton RSS390HF-4 MTM Quads of SEAS W18E001 511Bs TAD TD-2002

  11. #11
    Senior Member
    Join Date
    Oct 2003
    Location
    Texas
    Posts
    1,863
    Anne seems to be very concerned about chimney saftey, she left the same message on another board this morning

    http://discussions.probrewer.com/sho...gh-Attic-Space

    Or she's a spammer.

  12. #12
    Senior Member Champster's Avatar
    Join Date
    Apr 2014
    Location
    Wake Forest, NC
    Posts
    319
    Very cool project. Sorry to jump in so late but I somehow missed the post.

    Now you can see why I've become such a fan of Linkwitz Labs LX521.4. It is an amazingly articulate and coherent speaker system and surpasses anything else I've ever owned. I agree with your open baffle comments. Woofers when they are free to breath, front and back with no cabinet, produce amazing detail. The only drawback, is over driving them. You've hinted at doubling the 2245's. I see your last post is about a year ago. Did you ever do that? Did you use a MiniDSP to help smooth the frequency response and how high of frequency do you run them?

    Very cool project!!!!

  13. #13
    Senior Member
    Join Date
    Mar 2010
    Location
    Saint-Roch-de-l'Achigan
    Posts
    207
    Finally someone made it IB on this forum with JBP pro speakers !!!

    Congrats and enjoy real bass!

  14. #14
    Senior Member audiomagnate's Avatar
    Join Date
    Jan 2011
    Location
    Colorado and Georgia
    Posts
    1,022
    QUOTE: Very cool project. Sorry to jump in so late but I somehow missed the post.

    Now you can see why I've become such a fan of Linkwitz Labs LX521.4. It is an amazingly articulate and coherent speaker system and surpasses anything else I've ever owned. I agree with your open baffle comments. Woofers when they are free to breath, front and back with no cabinet, produce amazing detail. The only drawback, is over driving them. You've hinted at doubling the 2245's. I see your last post is about a year ago. Did you ever do that?

    Not yet, but I did add a couple of conventional "helper subs" for HT sessions. I haven't bottomed the single yet, but I've come close on 24 bit organ stuff. I've upgraded to L300's and moved the SVA's in the rear for HT BTW.


    Did you use a MiniDSP to help smooth the frequency response and how high of frequency do you run them?

    Crossover is 12 dB/octave at 50 Hz. No DSP, but the room is huge (63' x 24') with lots of irregularities and well damped so it's pretty well behaved. I've done lots of sweeps and it's reasonably flat over its relatively limited operating range.

    Very cool project!!!!

    Thanks, once you go IB, you'll never go back!

  15. #15
    Senior Member Champster's Avatar
    Join Date
    Apr 2014
    Location
    Wake Forest, NC
    Posts
    319
    Good call on adding the subs for HT. There is really no point in overdriving the 2245 and asking it to do a task that it wasn't designed to do. When you're ready, I would encourage you to get your hands on a miniDSP for a couple of reasons. First, it is super easy to set a lower cutoff frequency so that you can really protect that driver. You know how valuable and hard it is to get a 2245 re-coned with a real JBL cone these days. Secondly, the trouble with passive crossovers at these frequencies are the size and cost of the parts. The DSP solution allows ever steeper slopes to transform that driver into a true sub and get it out of the upper frequencies altogether. I use a pair of 2245's in 9cf cabinets with my LX521.4 system and take a slightly different approach at determining the upper frequency of the JBL. The 2x10" seas drivers are wonderful but in the cabinet-less LX521.4, they really start making some shockingly large excursions below 35hz. There is also a sense of loss in acoustic energy as the frequency gets that low, so, to protect them, I use the 2 unused digital channels in the minDSP 4x10HD for a 24db/oct 35hz crossover point and then in the PEQ set a 24db/oct lower cutoff at 17hz. For most program material, the 2245's, honestly, rarely has much to say, but when there is program material in this region, they bring a lot of energy to the bottom end that the 2x10" drivers just really struggle to do on their own. I, too, like organ music and movie soundtracks and, on the occasion when I get into that mood for bass heavy material, the 18"s really show their merit and this allows me much higher volumes and a much more realistic soundstage.

    Have fun with your project!

Thread Information

Users Browsing this Thread

There are currently 1 users browsing this thread. (0 members and 1 guests)

Similar Threads

  1. Jbl 2245h
    By BillR in forum Lansing Product Technical Help
    Replies: 5
    Last Post: 04-23-2010, 10:59 AM
  2. Box for JBL 2245H
    By Niklas Nord in forum Lansing Product DIY Forum
    Replies: 4
    Last Post: 04-22-2003, 01:45 PM
  3. Box for JBL 2245H
    By Niklas Nord in forum Lansing Product General Information
    Replies: 4
    Last Post: 04-22-2003, 01:45 PM

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •