winISD,custom avatar cabs....

Discussion in 'Amps and Cabs [BG]' started by Magman, Feb 19, 2003.

  1. Well, to answer my own question about sticking a more expensive emminence driver in an empty avatar cab I started using winISD and looking at the curves.

    It struck me the non-custom cabs are tuned quite high giving a 'hump' at 50hz (in the case of B15), whereas a lower tuning smooths out the curves on the drivers it seems... so presumably you can do that just by altering port size?

    For those not interested in the carpentry of cab-building, customizing existing designs on pre-made cabs seems like a fun way to proceed for the tinkerers among us, and learn more about transducer engineering along the way.

    So, maybe folks already have workable designs ready they have tested (or even just sound theoretical ones)? Could they be put on the web somewhere? Like - "buy driver x, increase port length on avatar cab by y inches and you get z increase in 30hz bass response"

    I mean, with the right drivers, a 210 or 112 could be nearly flat down to 30hz.... at the expense of sensitivity.

    EST-Ltd ---- did you use ready made cabs for your 12inch subs?
    How did they turn out?

    One idea I like is have a small flat full range cabinet (lets say like the B112) which can be used for hi-fi, parties, home theatre, instruments *whatever*. It certainly wouldn't be audiophile quality, but would have better tweeter and lower bass than a standard bass gtr cab or average PA cab.

    For volume you just buy more of them and daisychain. Obviously not many hi-fi's have 400 watt amps, but then you wouldn;t *want* gig-volumes in your home very often.
  2. ESP-LTD


    Sep 9, 2001
    I was holding off until I could feed them some serious power, but I'll tell you what I can.

    I have a B112 and it is a nice unit for highs. Interestingly, the back is inset a bit so it has less cabinet volume than you might expect from the outside; I think Bgavin calculated it to be about 1.6' . That was not enough to make my JBL's as happy as I wanted so I built some boxen myself.

    I am not much of a carpenter so I paid my lumberyard to cut my wood for me (e-mail me if you want a Word doc describing complete construction procedures). The end result was about 18x15x24 external and weighs about what the B112 does; 40# or so.

    I ended up with about 2.4' and tuned it to about 26-28hz (calculated). I kep the 18" footprint of the B112 so my "stack is tall and skinny, putting the B112 just where I need it as a monitor. I have a QSC RMX-1450 which should allow me to run the B112 at 300w and the subs at 250w each (rated power) and still have headroom (handy at a 2 ohm load).

    So far, at the low volumes I have tried it has been very slick indeed. It's amazing how a 5 string sounds when the low B is as clear as any other note. Not "only a little muddy", it's flat to 30hz and sounds very good indeed. Interestingly, I wired one box out-of-phase by accident. It was VERY strange to run 30hz on 2 boxes that cancelled. I pushed about 40% power and it was just barely audible, although it made the floor shake in an interesting way.

    I hope to wring it out at power this week at practice; I think for practice a B112 at 30% and a sub running 80% ought to do well in a loud rock practice. As I up the volume from there I imagine I'll need the 2nd sub to keep up. I don't think I'll need a second B112.

    Total investment for (2) subs was about $300.
  3. ESP-LTD


    Sep 9, 2001

    I believe I calculated that a B112 box could be tuned to 45hz (or close) by blocking one port and putting a 12" tube in the other port. I don't think I'll bother though; biamp is too nice.

    An interesting and cheap project is a 10" aluminum cone driver that MCM sells (used to be $20) with an Fs about 40hz. They have very nice highs; I used to use a pair of 2x10 boxen with those in them (2.5' sealed" until I finally smoked them with power (70w rating each; perhaps 50w would have been safer). I always liked the sound with a 4 string and the 2x10 cabs cost me $85 each to make; 5/8" plywood and carry one in each hand. I always assumed they were probably a lot like what goes into a Hartke Transporter, but I don't really have any proof. The rest of that series from MCM has specs that didn't do much for bass, but the 10's were a great fit.

    Actually, the sub design has enough room on the face for a 4-6" mid and I noticed that Parts Express has a 5" for about $10 (94db) with a 400hz XO point (the theoretical top end of the 12" JBL's. I didn't go that way because I wanted to avoid crossovers and such. I can certainly recommend the JBL GT Series subs (and that's their CHEAP stuff).
  4. The subs sound like they are really nice, and cheap too.
    Be interesting to know how they are in a louder situation.
    That driver is quite a bit less sensitive than the emminence 12;s though... so fiddling in winISD the actual output is similar down at 30hz (at least with the delta 12's in a bigger cab), just that Delta 12'LFs are a lot louder in the rest of the frequency spectrum (and thus non-flat).

    Theoretically, it looks like the avatar b212 delta LFcab, estimating its volume at 140litres, if it were tuned to 30hz (rather than 50), would be 92db sens at 30 hz --- pretty good.
    It should be thunderous.
  5. ESP-LTD


    Sep 9, 2001
    The real hangup (as I understand it) is that asking the Delta 12's to do much below Fs is asking for potential problems (group delay between Fs and the lowest note, and distortion as it exceeds Xmax). To really get low and stay clean, you have to have Fs below your lowest note, and tune the cab below your lowest note as well. Then you have to live with the fact that subs will have poor sensitivity.

    I bet they sell a lot of 2x12 boxes, but I don't want to carry one anymore than I want to carry a 4x10. Hifi 1x12 boxes have plenty of appeal to me though.
  6. Right.... sticking a 200 watt 30hz sine wave through the delta may causes them to barf, whereas your subs will just rumble away happily! So though the sub are less sensitive, the max SPL at low freqs is much better than the delta or other non-sub woofers.

  7. ESP-LTD


    Sep 9, 2001