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In Reply to: RE: Labyrinth Transducer or Karlson Speakers. posted by BugC on July 02, 2007 at 22:28:51
x15 is very small at 2 cubic foot rear chamber so can have rolloff from flat ~80Hz half-space -- Fulmer's pipe doesn't have much volume, nearly constant area and not sure how would behave in reality (sure looks cool!) do you know its Thiele-Small paramenters? I'm not at all familiar with 415Ax15 probably wouldn't need all those reflector panels - 115 had one basic panel and it had a big vent reducing reflections - -CN didn't have a x15 plan so built cabinet 28Hx20W x 16D with 25 degree baffle, 10 degree board above the baffle and a deflector which holds a 9 inch k-tube at ~35 degress tilt below horizontal. Carl always uses adjustable lowpass choke
Edits: 07/03/07 07/03/07 07/03/07Follow Ups:
Hi freddyi!
Thank you for your thoughts on the LT and K speakers. Sorry I don't have the T/s parameters for the LT. There's not much info about the Altec 415A biflex (even in the Altec and Lansing Heritage websites). All I have of them are they were made in the 50's with a freq range of 30-14,000 cps. Power handling is 25 watts. Max cone resonance is 45hz. Impedance = 8 ohm.
Might try the LT first since it's easier to build. Will add an altec 811b horn with a GPA 902-8a compression driver or a JBL 2402 bullet tweeter for freq above 3000hz. Will compare this to my BIB speakers using 8" FR drivers.
Cheers,
BugC
Greets!
These speakers were designed for good performance in 8-10 ft^3 cabs depending on tuning, so both these cabs are a bit small if performance much below ~70 Hz is desired. Also, no personal experience, but I imagine the K's high throat pressure will severely over-damp, if not outright audibly modulate, the 415's separately suspended mid/HF diaphragm.
GM
Loud is Beautiful if it's Clean!
Hi GM,
Thanks for the advice! ... Would the 8-10ft^3 cabs be bass reflex or the sealed type for optimum performance? The BR cabs I made earlier has an internal volume of 6ft^3 and a duct measuring 2.5"(H) x 8.25"(W) x 2"(D). Tuned at 40hz (using online duct/port calculator). When listening to this I sometimes get a loud farting sound in the low freq region (sorry for the choice of word but that's the closest I can get to describing what I hear). Am thinking of making the port 4"(H) x 11"(W) or covering the port (ala sealed type) and give them a listen before I embark on my new project ... Just thinking, if the 415A's were used in the Altec Santanas, which were roughly 5ft^3 and were sealed, would they perform better in a 6ft^3 sealed enclosure? ... Pls feel free to share your thoughts on my "whacky-style" of building speakers.
Cheers!
BugC
Greets!
You're welcome!
They were all reflexes.
OK, I get a ~37.93 Hz Fb, the on-line calculator's math is heavily simplified and even then mine can be high or low depending on the driver's and vent's location on the baffle. Anyway, if your system feeds the speaker signals below its Fb, it will oscillate uncontrollably, increasing with decreasing frequency, causing the 'farting' sound of its suspension going extremely non-linear, so tuning higher as you suggest would just aggravate the problem.
Larger cabs tuned lower tend to protect the driver better overall, though of course a sealed or ~aperiodic (well stuffed TL) alignment will protect it all the way down against over excursion, though not from excessive thermal power or amp clipping issues. If you're going to stick with the 6 ft^3 though, I'd seal it up or at least convert the vent to ~aperiodic to improve its transient response. As you shrink a sealed cab it becomes increasingly under-damped, so by most (all?) folks standards around here they would consider this as going in the wrong direction for best performance, so lacking any driver specs my SWAG is that the Santana's cab would make it sound a bit less controlled, though it will have a bit more mid-bass 'slam' as the trade-off.
GM
Loud is Beautiful if it's Clean!
H GM!
Thank you for your advice and so sorry for the late response. I'll try your advice this weekend to seal up the box and see how it sounds like after. That would save the baffle board from being "mutilated" for the time being. Actually, I was just trying to follow the recommendations from old literatures on port sizing vis-a-vis cabinet volume. IIRC boxes were tuned using the drivers free air resonance or I completely misunderstood it! ;-D . However, I read somewhere (I think it was from the Altec or Lansing Heritage forum) that this was old way of tuning the box. Now there's a much better way! For lack of bettr understanding of how this is done, I just followed the old advice! (See how whacky my way of building a box) hahaha ... MY next step after this (sealing the box, if it does not sound right for me)is to make an adaptor board and try the JBL 123A-1 on the 6ft^3 box ... BTW, I tried the 123A-1's in my friend's half-horn. The bass was strong and punchy. It sounded a lot better than one of the 12" vintage altec driver we compared it with. He's inviting me over to listen to a Western Electric driver mounted on his half-horn. He claims it sounds a lot better than the JBL 123A-1's! Thanks again!
Cheers!
BugC
if 415 is as "bright" as say an SP15B then probably have pretty good balance in K15 - -SP15B sounded pretty good - (lacking some snap compared to stronger coax woofer) and when I measured the paramters - saw Qts > 1I don't think inner cone modulation would be a problem or exist - but don't have Biflex to test
Hi freddyi!
Thank you for the additional info about the Karlsons. The more I read about them, the more I'm inclined to build them! ... If the 415A's won't do well with the Karlsons, I'll try the JBL 123A-1's. My gut feel however, is both the 415A's and the JBL 123A-1's will work well with them ... The 415A's aren't "bright". For me, they present a very vivid midrange. I'll just add the GPA 902-8a comp driver or the JBL Bullet tweeters for the highs. I am hoping the Karlsons will aid in extracting a little more bass from the 415A's to add weight to the musical presentation.
Cheers!
BugC
D123A have large vas -never had one in K15 --K15 will play alright with 15" coaxial --too bad Eminence didn't add 1lb of magnet to Beta 15cx woofer - then it would have worked well and sold for about $115-$120 - Beta1 5cx is listenable as is but has some LF peaking -- P-Audio coaxial should be decent
Hi freddyi!
Thank you for the advice! If the JBL 123a-1 wouldn't work well with the K15, I will try the Pioneer PAX-30G (I have a pair lying around). It's a 12" full range driver with a horn at the center (coax).
Cheers!
BugC
if you go K15 - might consider an adaptor board to allow 15" at some point
Hi freddyi!
Thanks for the tip! I'll cut it for the 15" and then make an adaptor for the 12".
Cheers!
BugC
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