doityourself

I began to experiment with my Speakerlab SK bass bin to get rid of the 100-200hz bump that makes the bass sound honky. I was originally using an Eminence 5415 woofer that has specs similiar to the K33. I was using a 6.4mh coil to kill some top end sound and that's what I had available at the time. I ran some freq. response with some other chokes and one with an extra capacitor. I was wondering if I could design a notch filter that would take care of the bump. What I discovered is that my 6.4mh (Klipsch uses a 2.4 on a 4ohm driver-mine's an 8ohm driver) coil doesn't do too bad a job but when I hooked up what I believe to be about a 9mh the lower bass jumped up a few db's and the upper midbass didn't chan ge a whole lot. I than ran freq. response with an 80uf capacitor to change it to a 12db rolloff and the lower bass dissappeared. The first chart is the 12db rolloff circuit. It would sound terrible (I didn't bother and listen yet). The second chart is the 6.4mh plus the 9.0mh coils hooked up in series and you can see a jump in lower freq. and it tended to stabilize the upper midbass without rolling off the 400hz range substantially. This combo should theroretocally resuilt in no resonse in the 400hz range and shouldn't affect the lower bass. I would suppose that the impedance of the speaker is affecting my calculations. I wil give a listen to the 6.4 +9.0 combo and see how it goes.

I just looked at Eminence's website and the Delta 15 would be 3-4db more efficient and have a higher resonsance. Perhaps the K33 is the best choice at this time or try and find some cheaper 15inchers on ebay or something that could be tried out. Come to think of it though, the Delta 15 with it's higher efficiency might be ok because it's an 8ohm design and not a 4 ohm like the K33 and the extra sensitivity would be wanted but the higher resonance might result in less low bass but you've got a subwoofer to handle the extreme lows anyway-right? I would consider the La Scala's as a good alternative if you have a subwoofer. I lot easier to build and I think they look cool but not being tucked into a corner would take up more room.

Eminence tells me that the Delta15 is a close match to the K33. I haven't checked the specs on that speaker to see if they're close. I would venture to guess that the K33 was designed after the horn and not the other way around like a previous poster suggested. Just a few simple mods were made to the horn after the K33 was used. With my speakerlab clones I'm using an Eminence 5415 15incher that has close specs to the K33 and I've modified the throat area starting out with an opening of 3x13 and motorboard to doing away with the motorboard and opening the throat to 6x13 and adding sound dampning to the sealed chamber without any noticable change in response. I would predict that woofer selection isn't really that critical. Obviously Klipsch didn't think woofer selection was that critical on his designs as he used the same one for the Khorn, La Scala, and Cornwall. Let's see, was the La Scala designed after the K33?

Oldbuckster, that comment doesn't even make sense. After all the posts about how my basshorn behaves like a Klipsch and how I like the sound of the midrange (vs the horn), I'm trying to improve on the sound. I don't think I would be satisfied with the Klipsch either. If you like the Klipsch so well, why are you visiting the updates and mods section? If you want your speaker to sound like a Klispch, don't mod it and update it, leave it alone!

The freq. response doesn't look a whole lot different than the published Khorn response. The 125hz range boost is my biggest gripe about my speaker, the Khorn, and LaScala and probably any loaded bass horn. I used to use an eq. to lower that range but it's getting harder to find a reasonably priced reciever (I use my system for my theatre setup) that has some preamp input, outputs, or even monitor outs). I have my DVD player hooked up through the 6channel input (Yamaha receiver) and cd input. The 6 channel input doesn't allow tape monitor to be used and I loose the subout on cds but through the cd input the subwoofer out does work. I would love to use the dvd player's dolby II decoder for some cds but I loose the subwoofer output unless I put the main speakers on small. The reason cost is so important to me is that I live in a small midwest town area and my wife hasn't worked for the last 12 yrs and my 2 boys are getting in High School and expenses are going out of the roof this yr. I built these speakers 18 yrs ago and they're still going strong but with some more tweaks can get them even better.

Does anyone have any comments on the Freq. response graph I posted? It really looks pretty flat to me except the 125hz range. Perhaps a notch filter at that frequency? Right now I'm running a 6.4mh coil for the woofer and that equates to aprox. a 200hz 6db rolloff. Perhaps adjusting it down another 100hz but that would leave a whole at 300hz or so.

D-Man, you're my man! Does your SK have the bass contour knob? What is it? Thanks for any info.

John, I don't understand your dislike on the meter. For the purposes of the midrange response this should be more than sufficient. The Eminence woofer is 1db less efficient than the K33E and it's 8ohm so this should put the sensitivity in the 100db range which is where the Audax PR17 is. Here's a copy of the Speakerlab SK specs and description of the horn. Notice how the horn doesn't even fit into the wall. That's the way mine are made. No need for the extra material in the Khorn. The reason the front is octagonal shape is to make room for the midrange and tweeter in front of the bass bin.

The Khorn plans I have talk about a bass contour knob. These are the later plans that house the PR17 midrange driver in front of the bass bin. I ran a freq. response of the speaker with the subwoofer running. The bass bin has and Eminence driver with 6.4mn choke. This bass driver is similar to the K33E except is 8ohm with more power handling capability at least according to Eminence. The topend drop is because of using a Radio Shack sound meter turned 90degrees from speaker to make it more accurate in the 8-10khz range. Maybe I don't need more midrange. The meter was positioned about a meter in front of the mid and high freq. box.

I emailed Speakerlab to see if they know anything about the bass adjustment knob. I don't see why one has to spend big bucks for good sound. This thread went from criticism to helpful suggestions back to criticism that is simply not needed. Maron, have you heard the PR17 driver? I didn't think so.

One more thing, in the Speakerlab K plans I used (which had the PR17 in the design) there was a mention of a bass adjustment knob. I didn't have any crossover schematic but from what I can tell it was simply an Lpad on the woofer. Can anyone confirm or deny this?

Thanks for the input. I'll try and post some RTA graphs in a couple of days and see what you think. Perhaps the dip from 400-1K is to my liking anyway. The Cornwall certainly has a dip in the midbass. I've heard of putting the PR17's in a smaller encloser to raise the Q to boost the lower range. I'd try some K401's and K55's but one is going to spend over $200 bucks at least and I'm not sure I'd like the midrange horn compared to the PR17. Where can a guy pick up some T2's and at what cost?

Maron (is that your real name or a nickname someone gave you), if you don't have anything constructive to say....

I have some homemade khorns with an Audax PR17 6.5inch midrange and EV35 tweeter. I would like some more output from the midrange. Currently running it without any antenuation. I was told by djk that the T2A autoformer could be used to increase the output. How does one hook one up to increase output? Run it backwards? The Audax is rated at 100db efficiency but not in the 400-2k range where's it's slightly less. Where does one buy one and at what cost? Thanks. Maybe it would just be easier to put an L-pad on the woofer section to decrease the bass output in relation to midrange?

Khorns are probably down 10db at 40hz vs 125hz. They will sound weak without some some eq. or a subwoofer. Compare the freq. response of the Cornwall to the Khorn. What do you see? The midbass (125hz range) is down 5db compared to 40hz and the Khorn, Belle, and La Scala are all up 5db in that range for a difference of 10db. He would probably be happier with the Cornwall if he's seeking low end output. My homemade speakerlab horns have no backpanel to seal to the corner because there is no benefit at lower frequencies. The drop in low end response is a design characteristic and most reasonable size horns will have it. I used to use a 10band eq. and boost the 30hz range 12db to make up the low end but a couple of yrs ago built a 12inch 250 watt powered sub and it won't quit keep up with the khorns but will add that extra bottom octave missing up to ear shattering levels and that's with a properly configured 3.5 cu ft. sub made with a car sub of the proper specs.The Khorn just will not have the lower octave no matter what you do.