KHorn Bass Problem

[Brockybear]

I have just set up my system in the new lounge room. The walls are Drywall and Floor carpet on Concrete slab. Both KHorns are pushed tightly into each corner and the rear soundboard fits snugly all thw way down. I checked this by pulling the speakers away and you could see two rubber marks from the sound board running the full length on thw wall. I did note that with the KHorns in place there is an even space of 1/2 an inch detween the walls and the top horn unit from front to back. I cant push the speakers back any more as the soundboard is hard into the corners.

The Bass at the moment is terrible, just nothing there. Each KHorn is driven with a Cary CAD 211 Mono Tube Poweramps hooked to a Cary SLP 05 Tube Preamp. Given the room width I use a SET monoblock to run a Klipsh Heresy as a summed mono center. I have checked polarity and have run out of ideas.

Room dimensions are 26 feet wide X 22 feet deep X 12 high

Any ideas?

[pzannucci]

Typical problems - wired in phase, etc.

Are you sitting off to one side and when you sit in the middle, does the bass change? I know what if my khorns are out of phase, sitting to the side will give a lot more bass where the length works with the frequency but noting in the middle and vis versa when in phase and sitting in the middle.

Also you have verified the connections are correct (mid - woofer - tweeter) and both bass horns are working?

[djk]

+1 on checking the phase.

Not having a good seal in the corner affects the mids in the 250hz~400hz region, not the bass.

1/2" sheetrock does not make a good corner, the bass below 100hz goes right through it.

[mikebse2a3]

I have checked polarity and have run out of ideas.

A few questions just to make sure we aren't missing something.

(1) Are these speakers new to you or have they been used by you in another room?

(2) If the speakers are new to you could someone have been inside them and maybe crossed wired a woofer by mistake?

(3) If they had been used in another room how was the bass?

(4) Instead of just visually checking the polarity of the loudspeeakers have you actually changed the wiring/polarity to one of the speakers to test for the lack of bass and if so (while just paying attention to just the bass response) was it improved or worse?

mike tn

[Brockybear]

Thanks pzannucci for the advice. I have traced all the connections from the preamp to the crossovers and all the wiring is in phase. Everything sounds great to about 250hz then it rolls off somehow. I wonder if the problem is the amps running at such a low power output. The CAD211's are 150 watt a channel but barely tick over with the KHorns. Could the output transformer be the problem?

[Brockybear]

Thanks


mikebse2a3 for your suggestions. I put the swaped the polarity on the left horn out of phase and the bass was even worse.

Yes the speakers were purches back in 2002 and I had them in a room with a wooden floor and stone walls. Now they are on a concrete floor with drywall. The bass was better in the room with a wooden floor.

[Guest " "]

the amps are fine, they go down to 18hz. plenty of power too, even in triode mode. the preamp is fine ast well. my guess....the problem is the seating position. nether of the seating "things" are within the sweet spot. take a sheet of paper and oreint it as if it was your room. you have a 26ft side and a 22 foot side. draw a diagonal line from each khorn position at a perfect 45 degrees. where they intersect, is the middle of the sweet spot. sit on the floor, in the middle of your two seating "thngs" and face your system. does the bass sound better? also, take a look at the attached pdf. if your amp has 4, 8, 16 ohm taps, put the LF section on a higher impedance tap and the hf section on a lower impedance tap.

McIntosh Autoformer Training Page.pdf

[russ69]

It's totally possible the room mode is canceling the bass. You might have to move to another wall. If that's not possible a stereo set of subwoofers will help with the cancellation modes. Sometimes rooms can really kill a system so you have to be flexible with your set-up.

[Brockybear]

Thanks russ69 I have a set of Transmission Line Subs for my home theatre I will wire them up and see if this helps

[Chris A]

I had them in a room with a wooden floor and stone walls. Now they are on a concrete floor with drywall.

Your room dimensions and approximate seating positions don't seem to be problems--at least from a calculated room modes standpoint.

I'd say that you need some bass EQ on your Khorns since going from stone walls to drywall will probably pull something like 3-6 dB off of the room response below about 50 Hz relative to what you were used to hearing in your other room with stone walls. I'd recommend a bass tilt filter (sometimes called a shelf or a ramp) resulting in +6 dB or more boost at 31 Hz. You could put some PEQ filters around 31-80 Hz to achieve a smoothly rising response in-room from 100 Hz downwards. At least that's what I'd do.

Or, if you really got motivated, you could do something like Mike B. did (see photo).

Chris

[garyrc]

....

Not having a good seal in the corner affects the mids in the 250hz~400hz region, not the bass.

1/2" sheetrock does not make a good corner, the bass below 100hz goes right through it.

I agree with the above. Room gain may depend on rigidity. Is your sheetrock really 1/2 inch? Are the studs 16" on center, or are they more widely spaced?

My Khorns had great bass in a room with 3/4 ply + hardwood veneer walls with studs @ 16" O.C. THEN we moved, and the new room had floppy sheetrock and the bass went away. At high SPL one could actually see the walls flexing and feel them doing so by placing a hand on the wall. It seemed like they were moving about 1/2 " ... or more ... I believe they were acting as some kind of membrane absorbers. We recently redid the room with 3/4 ply walls covered with 5/8 sheetrock, screwed and glued with staggered seams. We haven't moved the speakers back in yet, but we are hoping to get the bass back.

I'd try walking the room (or rolling on a desk chair to put your ears at listening level) to find the points of maximum bass, and try putting the listening chairs in thos spots. In one room we had in the distant past, If one walked the room from back wall to front wall, there were distinct zones of intense bass and minimal bass.

If you eliminate all other possible sources of your problem, you could try gluing and screwing a very rigid faux wall (3/4 ply + finish veneer) to the existing wall behind your K-horns that extends about 5 feet out from each corner and perhaps considerably taller than the K-horns as well. I think Craig Stark (or someone??) thought 5 feet was better than the 4 foot minimum. Don't use furring strips or "cheaters" ..... make sure that the ply is supported at all points. Or, you could build artifical corners with 2 x 6s and 3/4 ply on each side, but that's harder, IMO. Rigidity!

[tidmack]

Out in left field a bit, but I think your K Horns are new
enough where the woofers are fused. Double check to make sure both woofers are
actually working. I'm embarrassed to say that I ran my K Horns for 3 days before
realizing that one woofer wasn’t working. Just something simple to double check...

Jeff

[JJkizak]

Something must be really wrong. With my K-horns I can sit on the roof, the next room, the kitchen, the bedroom, the house next door, the crawl space and be inundated with bass. And that's without a sub. Does anyone else in your family think there is no bass? Maybe a hearing check is in order.

JJK

[Chris A]

...THEN we moved, and the new room had floppy sheet rock and the bass went away. At high SPL one could actually see the walls flexing and feel them doing so by placing a hand on the wall. It seemed like they were moving about 1/2 " ... or more...

I have two tapped-horn subs--one behind each Jubilee (you can see them in profile picture). The flexing that Garyrc is talking about is present in my room at ~17 Hz up through about 34 Hz. The walls move enough such that any artwork on them will resonate if there is a picture frame attached. Thus, we have no framed artwork in the area of the subs/Jubilees. The fireplace liner and the recessed light fixtures also resonate at certain sharply defined frequencies.

It's difficult for me to justify modifying the room's walls to attach stiffeners due to the notion of having to undo it if we ever moved, but it may soon occur anyway in my room if I cannot find a happy medium on HT LFE boost vs. 2-channel operation of the subs. Right now, I set the two subs' amplifier gains for smoothly rising response down to about 17 Hz for music (instrumented in-room). This is outstanding for classical organ recordings and percussion pieces, but I have to remember to back the gains down for HT operation since the LFE channels in many movies today are so boosted that they result in bottoming the drivers in the subs on explosions/transients, etc. When there is a steady-state 20-25 Hz LFE signal, you get the feeling that the room is moving while seated in the listening positions, and those listening positions are located at response minima nodes close to the center of the room, so as you move toward the boundaries of the room while this is occurring, you actually begin to feel disoriented.

I know that I could permanently back off on subwoofer amplifier gains if the drywall up to about 6-8 feet high and deep from the corner were reinforced. That's what the palm of my hand tells me when I investigate the drywall flexing magnitude of my room's corners.

Chris [8-|]

[Chris A]

I know that I could permanently back off on subwoofer amplifier gains if the drywall up to about 6-8 feet high and deep from the corner were reinforced...

Or I could simply build a couple more tapped-horn subs (about $500US for parts/materials) and place them on the outside of the Jubilees with their mouths in the corners next to the other tapped horns, then drive them with amplifiers already in hand. That approach would have the added advantage of moving the Jubilees out of the corners a bit more for better imaging.

I'd call that option the "brute force method". But that approach might be a bit intimidating from the standpoint of the casual observer,[]

Chris

[oscarsear]

I had 82 Khorns and sold them. I purchased new 2004 Khorns with the AK4 crossover and the bass was quite hampered. I drove those Khorns with Cary tubes. But the bass was only slightly better when I switched back to my older Adcom SS amp. The eventual fix? AlK's steep slope crossover. Al allows you to trial his crossover before you are committed to buy them so testing them out was a no-brainer. I was able to directly compare the crossovers when I switched out only one speaker. The difference in bass performance was palpable, astonishing and frankly disappointing. The AK4's went away and now I can clear the room out with bass performance. People do perceive sounds differently and their hearing changes with age. But Klipsch does alter its crossover design according to listening groups. The AK4 was 'bright'. I noticed it immediately and so did my parents when they 1st heard the system (compared to my older Khorns). I do not know what crossovers would be in 2002 Khorns.

[Brockybear]

Hi Oscarsea,

I disconected the HF section and checked the woofer were working. Both sound fine but it seems like the HF section is brighter than the woofers. The crossovers are Klipsch AK3 units. I think I have narrowed the problem down to room accoustics and the brightness of the crossovers. Which model ALK units would you recomend?

[oscarsear]

I use Al's steep slope crossovers made for the Khorn. I also have shifted back to solid state electronics. I had a number of problems with my Cary equipment/tubes and now use and Accuphase E530 integrated SS amp.

[Brockybear]

I draged my Heresy speakers into the lounge and fired them up. They sounded great and had heaps of bass so I think the room accoustics are less likely to be a factor. I am going to do an inspection of the woofers, if they check out then it must ba a crossover issue.

[garyrc]

I assume each Heresy was placed where each K-horn was, Right?

My Heresy IIs have very little bass compared to my K-horns, including when they are placed on top of the Khorns (in a test a few years ago).... if your Hs have more bass, something is really wierd.

When the tailboard and its rubber gasket are pushed all the way into the corner, the tops of my K-horns are pretty much right against the wall, with just the slightest, barely visible gap.