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"V-Trac" Midrange Horn Upgrade For Khorns


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Greg -- there's no real point in using Al's 4500Hz ALK with your BMS/Beyma setup since the BMS easily reaches 6kHz. When I mentioned the 4500Hz ALK earlier in the thread, it was in the context of using it with the Community M-200 driver which only goes to 4kHz before it starts to nose dive. On a non-CD horn like yours, which has collapsing verticals -- the driver will get a lift in response at the highest frequencies (but probably not as much as the K-400 provides with the K-55). However, it will be enough to use with a driver like Bob's tweeter or the Eminence APT-200 (same driver). The idea here was to provide a lower cost alternative to the BMS/Beyma setup while still providing a substantial increase in performance over the K-55 and 1" exit horn options. The Community M-200 is the driver found in the Avantgarde Trio, so I wouldn't be so quick to write it off as a "compromise". In fact, it's even possible that the M-200 driver might sound better than BMS. The BMS has an internal compression ratio of 10:1, while the M-200 has one of less than 2:1. To get a better understanding of what that means, you might want to compare the distortion plots of the BMS 4591 and M-200 (related but unrelated, the Klipsch Palladium uses an inverted cone with a compression ratio of 4:1). We had some email exchange about these 2" drivers a year or so ago where I shared this stuff with you -- I guess you just don't remember. The point wasn't to provide an "on the cheap" option with your horn -- but another high performance option at reduced cost. The BMS/Beyma option is $1300. The Community M-200/Eminence APT-200 option is $700.

http://www.parts-express.com/pe/showdetl.cfm?Partnumber=290-536%20%20%20%20%20%20%20%20&FTR=apt-200&CFID=3082288&CFTOKEN=20830964

m200.pdf

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I was too quick to judge the Community driver option I guess.

I wanted to try the 4500 Universal option because I wanted to find out if I liked the sound better. I knew both the BMS and the Beyma would handle it either way. What I still don't know is if my horns will perform well up to 6Khz. There's no reason why they shouldn't, but without a curve I'm not positive. I'll be sending a horn out for testing tomorrow, so I'll know pretty soon.

Greg

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I have been working on my V-Trac demo units, and today I finished up the wiring and made the wood box for them to be shipped in. I brought them to my house to test them to make sure they sound like the ones I have and that everything works properly.

So, I took the tops off my Khorns, and set up the demo units and sat down for a listen. The demo units have the 16ohm driver instead of the 8 ohm, so I knew I would need to adjust the tap settings on the crossover to get the attenuation right. At first the mids were way too hot, so I adjusted, listened, adjusted again, listened. Then I realized that the bass wasn’t right somehow, it wasn’t just that the mids were too hot, the bass wasn’t as strong. Then it dawned on me . . .

The demo units are just the mid horn and the tweeter hangs off the side, there is no cabinet around it, it just sits on top of the bass bin. When I took the tops off the Khorns, I also removed the top of the horn mouth, and that made quite a difference in the strength and punch of the bass!

Crap! So I put the tops back on, put the demo units on top of the tops and sat back down for a listen, and sure enough, the bass was back to normal. They sounded ok with the horns up top, but not as good as when they’re down a little lower where they should be. I don’t know what to do now. I really can’t send wood plates around the country to make the top of the bass horn, and it’s too much to ask people to take their tophat apart and insert the V-Trac. I guess the demo on top of the Khorn is going to have to suffice.

Greg

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I have an interesting observation.

When I listen to the BMS/V-Trac horn NOT attenuated as much and too hot in the mix, the sound is even better quality than when it is attenuated and properly mixed. Even after I adjust the volume up so the mid is the same volume as it was before when it was too hot in the mix.

Why?

Is the attenuation changing the quality of the sound or just the output level?

Anyone know? Dean?

Greg

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Attenuation IS output level. Something I've been saying for years is that there is a direct relationship between how loud people listen and how they like their networks set up (squawker attenuation). People who listen loud like the squawker dialed down, and people who listen at low to moderate levels like it jacked up a bit. When I had the Jubilees, I really liked the sound with no attenuation (no resistor) with just a twitch on the volume control knob of my tripath amp. I thought that sound was pure magic. However, if I turned it up at all the top would just run away from the bottom and it sounded terrible. I had to attenuate quite a bit if I wanted to crank it up.

As for the other issue, you're not getting more bass because the top is over the horn section. What I think is happening is that when you place your horn assembly on top of the Klipschorn, it's increasing the physical distance between your squawker and the bass horn, which may be changing the phase relationship and causing a drop in response somewhere. That's just a guess, I could be wrong. At any rate, people in on the demo should be prepared to remove their top sections and hear it the way it was meant to be heard -- heck, you can remove a top section in 10 minutes.

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Thanks Dean.

There is a definate difference in bass not having the top of the horn mouth covered, it was quite noticeable. When I first put the demo units on top of the bass bin, without the top of the bass horn covered, the sound was amazing. Too hot in the midrange and the bass had lost it's punch and definition, but the sound of the midrange was awesome. I've heard people say that there IS something to having the mid horn and tweeter out of a cabinet and sitting in the open on top of the bass cabinet. This is something I'm going to spend some time working on in my own designs.

I agree with your observation about volume levels in relation to squawker levels. Too bad we couldn't make these adjustments from a remote control while sitting in our listening chairs!

Greg

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I agree with your observation about volume levels in relation to squawker levels. Too bad we couldn't make these adjustments from a remote control while sitting in our listening chairs!

Greg

I kinda solved for this problem by accident. Using an active crossover in 2way config. with a little 5watt tube SET for the squawkers and a 60watt SS for the woofers. The relationship between the squawkers and woofers seems to stay consistent throughout the volume range. I did not appreciate that until I went with passives. Without an active crossover it can sound good but now there seems to be a sweet spot in the volume where the top is perfectly attenuated. Im my case as the volume increases so does the squawkers lack of attenuation.

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Why not cut out a "home plate" and ship it with the rest of the parts so people with Khorns can properly seal the bass cabinet and still just set the new horn on top without disassembling their own top hat?

I was just sitting in my living room mulling the situation over and basically came up with the same thought. The reason I was resisting is because I spent five hours yesterday building a box for the horns! It's a really nice box.

But I've decided I'm going to start over on the box. The tops and bottoms of the box will be the shape of the homeplate, maybe just a couple inches shorter, which will not affect the bass output, but will help keep the size of the unit down. You will take the screws out of the top of the box and pull the top off, which will have the horns, drivers, and crossovers attached. Flip it onto the top of the bass bin and wire it up. Then flip the box over and do the same thing with the bottom of the box and the other horn assembly. Easy. I wish I had thought about this prior to yesterday.

Greg

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I kinda solved for this problem by accident. Using an active crossover in 2way config. with a little 5watt tube SET for the squawkers and a 60watt SS for the woofers. The relationship between the squawkers and woofers seems to stay consistent throughout the volume range. I did not appreciate that until I went with passives. Without an active crossover it can sound good but now there seems to be a sweet spot in the volume where the top is perfectly attenuated. Im my case as the volume increases so does the squawkers lack of attenuation.

Cool.

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The top and bottom of the shipping crate double as the plate that covers the bass horn. They are attached to the horns.

The whole thing weighs 75 lbs and will cost $100 to ship across the country. Craig is going to cuss me out when he gets this.

Greg

post-11090-13819464248548_thumb.jpg

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Guest David H

Should I start another thread about the demo units?

Absolutely, this upgrade needs to be heard. How long is the trial? Genius idea.

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Greg absolutely killer!!! great job!!! This is a stroke of real genuis!!!

Jay

Thanks. We'll see if it's genius, or a lesson in how to watch a couple of grand wither away. Still worth it to me, I'm going to have fun getting all the feedback from listeners out there. Hopefully people will send pictures, and I hope everyone signs the inside of the shipping box. It will be interesting to see how the shipping box gets more and more road-worn.

Greg

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