Crossover frequency for sub matched with K-Horns

[jstanton8]

I'm having an unpowered sub built for me. It's going to get a split signal from the head unit, so I will need some sort of crossover.

My question is: which of the following low pass crossover frequencies would be most appropriate: 50, 70, or 100 Hz? Keep in mind that the sub'll be paired with K-horns...the sub itself is a 5 cu. ft. box with 15" Stryke driver and two 18" PRs. It'll be used for both music and HT...

Thanks,

J Stanton

[j-malotky]

JS

I believe the Khorn rolls of at 33HZ. 50 should be good. Want to keep it low to avoid too much boomyness. Especially for music listening.

For HT since I have all full size speakers, I have them all set to Large. I have tried small settings on my forte, center and Heresys, but they sound better on Large.

JM

[jstanton8]

Hey Malotky:

Thx for the recommendation on the sub X-over frequency. I've got all my speakers set on large also. That's why I got K-horns for mains and KLF-30's for surrounds in the first place. I can't think of any conceivable reason to have those suckers set on small! However, my center (KLF-C7) is set on small only because I can't tell any difference when I set it to "large". I guess the C7 must be crossed over high enough that the large setting makes no difference...

JStanton

[Ray Garrison]

Is there any way you can go with a variable crossover, or if it's fixed, try different cutoff points / slopeds before you, uh, nail down the top of the box?

The KHorn interacts with the room in the bass more so than any other type of speaker - the room is, effectively, part of the speaker. The extension and relative output level at the frequencies where the horn is relying on the room's walls extending the horn mouth will be greatly affected by the room geometry and construction. If the KHorn and room are properly coupled and working together as intended, you might (*MIGHT*) find that a 50 cycle crossover is too high, and results in a big bass hump in the lower bass, say from 40 cycles through maybe 80 cycles. Which may or may not be cool, depending upon what you're listening to. If the Khorn and room and not optimally suited for each other, your KHorns may not be producing bass at the output level they could be, and setting the crossover level at a higher figure might sound better.

This is one example where you really need to be able to experiment to find out what works best.

Ray

[Frzninvt]

How will you be crossing over the subwoofer? With passive coils at a set frequency or routing the power into an electronic crossover and then to an amplifier to feed it. You could use a DBX 120X-DS that has a continuously variable (50-210Hz @ 12db) crossover built into it, or the Audio Control Phase Coupled Activator (PCA) that has a sub crossover in it, however it is not continuously variable you have to purchase additional chips for different crossover points but it is a steep 24db Linkwitz/Riley design. Just a couple of suggestions.

[Q-Man]

I use an Outlaw bass manager and have it set to cut the K-Horns off at 40Hz. I have my sub set at 45Hz.

[jstanton8]

What I was going to use was the following Behringer Equalizer. (see below):

http://www.behringer.com/02_products/prodindex.cfm?id=DSP8024〈=eng

I had come up with the 50 and 100 Hz figures because that's the frequencies that the Parts Express Low Pass FMODs come in. They act like active crosovers in that they go in-line right after the head unit and before the amp/pre-amp. But I guess you can count on neither of those fixed values being ideal for my particular set of room modes. For sure the best crossover point will lie somewhere in between say 35-100 Hz, but exactly where is hard to say. The room they're in is roughly 17 feet (long wall, K-horn side) by 12 ft. deep by 8 ft. high, but is complicated by an "infinite baffle hallway" attached to the left side of the room (post left K-Horn) and a large overstuffed couch that take up much of the square footage of the room.

In the low range the Behringer equalizer has adjustable frequency bands at 20, 25, 31.5, 40, 50, 60, 80, & 100 Hz and 3 bands of parametric EQ which I thought would be plently of control to get the room "dialed in". Also has a real-time analyzer so you can see what your doing. And it's price is right, at about $200. From the webpage:

"The DSP8024 features a 31-band graphic EQ with a real-time analyzer and an Auto-Q function for automatic room measurement and correction plus three bands of parametric equalization. Further highlights include a peak limiter, an adjustable delay of up to 2.5 seconds, a noise gate and BEHRINGERs renowned Feedback Destroyer".

I was going to use the 50 or 75 Hz Parts Express Low Pass FMODs to filter the highs before they get to the unit. Then run that to the Pioneer pre-amp and that to the amplifier. Does that set-up sound OK?

The reason I'm going about configuring the sub like this (not using the LFE output)is that for some reason I have not been able to get the LFE output to produce any sound with an outboard amp. It works just fine for my KSW-15 and YST-80 subs (both have inboard amps) but when I try to run the LFE with an outboard amp for amplification, I get nada. I've tried an integrated amp and a separate amp (with and without a pre-amp) and the damn LFE just won't amplify that way! I know the amps work because they both do fine with a FULL RANGE SIGNAL, but hook them up to the LFE and nothing. Zip.

The pre-amp for the sub-amp is a full-fledged Pioneer Elite stereo pre-amp (will get the model # & I have the owner's manual if necessary). The amp is a Sound Code Systems pro amplifier that is rated 700 watts mono-bridged. A/V amp is a Yamaha DSP-A1.

The problem with running by splitting the full range output of the CD/DVD to the subwoofer instead of using the LFE for input, is that the subwoofer volume will have to be adjusted independently of the mains volume, which will be very inconvenient...

I am offering a $35 reward to the first person who can give me the solution to this problem, i.e, tell me what I have to do get the amp and pre-amp I have intended to use for this sub to effectively amplify the LFE output from my DSP-A1 (so I can get this custom sub off the ground).

Any suggestions?

Thanks,

J. Stanton

[IndyKlipschFan]

DBX has a real time pink noise generator called "The Driver Rack" that can analyze your whole system. Also includes many things you might or might not use. Including EQ adjustments and Limiter, Compression, etc., etc. The point here is this. It will take the info off of the signal generated specifically to your room and electronically adjust it to maximise the best possible sound for your individual room. This is an incredible piece of gear a a huge breakthrough of a product.

Look at http://www.driverack.com/products.htm

OK, it is a little overkill. But It will solve your problem keep everything "in balance" and as your biggest request...As you go louder or softer...Will keep everything in your home theater system singing along.

[jstanton8]

I just got done looking at the dbx Drive Rack 260. Looked real good except for the $999 price. If money was no object I'd go with the dbx but I think the Behringer unit has comparable features for 1/5 the price. The dbx sounds like it maybe has slightly more advanced feedback suppresion but then "feedback" may not be that much of an issue here since we're talking DVD/CDs and not live music from a mixing board...

[prodj101]

thats a good suggestion Ray. Whenever I've built speakers, and I'm nailing down the last board, I'm just thinking, "this damn well better work or I'm gonna be up the crick.