Something PWK said

[ClaudeJ1]

OK, you guys have given me an old disease back. I just got a pair of 511B's and 902 drivers. I originally had a pair with 808-8a drivers when I was 19 years old, mated to a Speakerlab X-over). I made 20 cubic ported boxes with Altec 421-8H woofers and an EV-T35 tweeter that was the best sound I ever had at the time, but I had been dreaming of Khorns since I was 14.

To get the cash for my honeymoon (poor boy and girl get married), I sold those DIY Altec speakers in 1977 for $650 to a friend (I had a grand in just raw components). The deal was my fiancee would co-sign (she had credit, I was a cash and carry boy).

The Khorns arrived about a week after my honeymoon, so we had a beer drinking/listening party with 2 buddies after kicking my new bride out for the afternoon. She understood.

Anyway, fast forward to 1985. She arranged a surprise visit to Hope for me to tour the factory in private. I maled a letter to PWK and he agreed to meet with me.

We discussed many things that day in his living room, including the false corners he built, the lone Belle Center channel, an how he had to shorten the K-400 to a K-500 make the Belles. Here's the quote, and this is important to DIY tweakers at large: "After we measured the K-500, I was conviced that we had made the K-400 a lot LONGER than it needed to be." So the K-400 could be made somewhere between the depth of a K500 and a K400 (K450?).

So now it looks like I will be building some LaScala bass bins. I have twin JBL 2404's, twin 511/902's, and a friend of mine pulled K-33's from his Cornwalls and put in some heavier duty motors......he's an EQ freak. So It looks like I will be buying lumber and X0over parts pretty soon..............................

[markgod]

Claude,

Sent you a PM ,would like a response before I leave Wednesday.

Thanks

[D-MAN]

Shorter wavelengths (higher frequencies) are less effected by overall horn mouth size than longer wavelengths, so it makes sense that the K400 could be shortened (decreasing mouth size) while keeping the flare rate for a lower Fc (400 Hz) without causing too great of variances in reactance that would effect the output response.

It also helps that the operational bandwidth for the horn is moved "upwards" by the crossover network in such a case, in essense, the horn has a mouth size appropriate for the "new" higher frequency but a lower flare rate. This foreshortening would be bad in a bass horn, but as the wavelength shortens with higher frequencies such as midrange and above, the debilitating effects on frequency response in the case of a midrange horn are not as great, and the higher one goes in frequency, the less the variance amplitude.

The first publishing of this was (to my knowlege) by Olsen in "Acoustic Engineering".

DM

[DrWho]

wow, sounds like you got yourself a keeper wife [Y] and cool story about PWK too.

So are you hoping to achieve the same kind of bass you've heard in the past with the lascala? If so, you should be aware that the lascala bass bin is only good to 90Hz, below which the output drops 6dB and plateau's out to around 50Hz before it drops like a rock (18dB/octave). It's most certainly not the same kind of sound you've been experiencing in the past. Heck, even the Heresy has flatter extension down to 50Hz.

[ClaudeJ1]

wow, sounds like you got yourself a keeper wife [Y] and cool story about PWK too.

So are you hoping to achieve the same kind of bass you've heard in the past with the lascala? If so, you should be aware that the lascala bass bin is only good to 90Hz, below which the output drops 6dB and plateau's out to around 50Hz before it drops like a rock (18dB/octave). It's most certainly not the same kind of sound you've been experiencing in the past. Heck, even the Heresy has flatter extension down to 50Hz.

If you look at my current system, it took me a long time to find sub-bass units to work semlessly with my Khorns and fill in the very last octave that is missing (other magical claims to the contrary). I find Active Subwoofers, the servo-driven "air pumps" to be less than adequate for musical listening, but fine for movies. The idea was to keep distortion LOW by having LOTS of cone area, motors, etc. to keep the cone excursion to the Khorn's 1/16th inch Xmax (inside the horn). But how do you make up for 10 db less eficiency?? You need 10X the power, but more motors and cones to keep the push on the drivers equivalent to the attacks (dynamics) of a bass horn. These VMPS things really do it, and form a solid 13 foot wall of speakers against concrete in total. I use the DTS canons from the Master and Commander movie as a demos, where you feel the flesh on your legs wiggling when shty go off, but, without touching any controls, you can still listen to regular CD's without boomy bass. I don't change any settings ever on my system. Unlike my brother who has to stuff a nerf football his subwoofer ports to make music listenable.

I got a steal deal on Ebay....$400 a pair, including the amp, but it was local pickup only in Sacramento (probably $2-3K new). Turns out I had done some consulting close to there just one week prior and made a few new friends. My new friend agreed to pick them up and box them for me. $300 shipping (300 punds on a pallett) they were at a local trucking company. The old VMPS Large Subwoofers are entirely passive with a 12" and 15" Active driver, a passive 15" (drone cone) in a large port near the floor. They are dead flat to 23Hz and halfway between my Center LaScala (which I have had since I was 23....almost 30 years) and the Khorns in height. Surround sound is a new thing for me and find the Onkyo power amps in the reciver to be wonderful. Yeah, I had tubes, blah blah blah, but SS is so good nowadays, ever since Matti Otala found all the TIM bugs in the seventies, all SS amps being produced in Japan today are good enough.

If you examine the response curves of the Khorn vs. LaScala, the LS's have a better upper cutoff to the mid-horn and don't suffer from the 300 Hz dip. I have given up on pure 3-channel (2 channel + bridged mono, same as PWK's home system) stereo and have managed to get really nice sound from my cheap Onkyo 5.1 receiver using the Neo6 (DTS) setting (refurb on the Net for $183 to my door). In that world, all the LFE information for movies or otherwise occurs at 80 Hz. based on both the DTS and Dolby D specitications. After much experimentation to the contrary, I decided that an 80 Hz. subwoofer crossover point was optimum for both movies and music (I used the Avia DVD and a sound level meter for setup in MY room). I have owned just about all the other Klipsch speakers at one time or another. My wife has had Heresy's since 1983, which I got for her for Xmas after she cashed in a small life insurance policy to get me the first CD player ever made....a Sony........she's a keeper alright.....we have been together for 31 years, now with 3 adult kids. My son has Klipsches also.

So, now that I am sold on subs, even for 2/channel listening at work, I find that LaScala Bass Bins will work just as well as corner horns for the purpose, with a superior mid-bass definition, and will cross at 500 Hz to my newly acuired Altec 511B/902's.

[DrWho]

Most people on the forums think I'm nuts when I say even khorns need bass [] The lascalas + THX Ultra2 subs have been my favorite sonic experience thus far into this hobby. I'm sure the VMPS subs are just as good (if not better). Sounds like you got a rockin system going on there - good luck with your lascala build.

Btw, is size an issue? You might possible consider building a pair of the Jubilee bass bins instead...[][]