USNRET Posted February 19, 2017 Share Posted February 19, 2017 I didn't want to jump into the Bi/Tri amp discussion but was wondering about using an active crossover to time align Khorns from a single stereo amp. What do I need and is there any info on settings? Quote Link to comment Share on other sites More sharing options...
Chris A Posted February 19, 2017 Share Posted February 19, 2017 If you just want to EQ your Khorns flat using a single amplifier channel, you can do that using REW and an active crossover if you're willing to install and use REW on your computer and connect to your preamp and a calibration microphone. However, the midrange and tweeter won't be time aligned. Unfortunately, in order to time align using an active digital crossover you need separate amplifier channels so that one or more channels can be delayed relative to the other amplifier channels to achieve time alignment. The best that you can do with passive crossovers is to add an all-pass filter on the midrange and tweeter channels, but that is practically limited to less than a full wavelength at the crossover frequency, and you need 1.4 wavelengths of delay on the midrange channel and 30 wavelengths of delay on the tweeter channel (higher frequencies = shorter wavelengths). However, the cost of adding two more stereo amplifiers is peanuts: you need much less than 1/3 the output power of a single amplifier to power Khorns since you're not using attenuation on the midrange and tweeter channels in order to balance them with respect to the bass bin channel. Basically, you could use chip amplifiers if tri-amping Khorns. If you have a favorite amplifier that you want to use, I'd recommend using it for the midrange channel. Here are the settings that Greg Oshiro used to tri-amp his Khorns in his living room: Thus far, I've helped two other members set up their digital crossovers in-room with their Jubilees, and one with his K-402-MEH. It's pretty simple and very fast once the first REW measurement is made. Chris Quote Link to comment Share on other sites More sharing options...
USNRET Posted February 19, 2017 Author Share Posted February 19, 2017 I bought the microphone and have a laptop to steal from my daughter. I powered up the REW with mic once (it made sound and I got a display) but frankly it may be just one more thing beyond me even after reading step by step tutorials. The other issue is that I am sharing the speakers between 2 channel amp and HT amp. Quote Link to comment Share on other sites More sharing options...
Chris A Posted February 19, 2017 Share Posted February 19, 2017 You can add delay to your tweeter simply by releasing it from the top hat mounting surface inside the top hat--and placing it on top of the top hat centered at the back of the cabinet approximately lined up with the K-55 compression driver below it (using your ears to listen when it is aligned: this occurs within +/-0.25 inches from the actual zero time alignment position). This costs nothing in comparison to a digital crossover and two additional stereo amplifiers--merely a bracket to hold the K-77 tweeter slightly elevated above the top hat in order to allow coverage of the tweeter in the near field close to the floor. (Marvel and at least one other person did this with his La Scalas/Cornwalls and have reported on the tremendous improvement on the resulting timbre and sound stage.) Of course, your bass bin won't be time aligned with the midrange and tweeter, but the improvement in sound just time aligning the midrange and the tweeter is a great deal of the potential improvement in time alignment. Chris Quote Link to comment Share on other sites More sharing options...
USNRET Posted February 19, 2017 Author Share Posted February 19, 2017 I guess I was thinking I could something in the 'analog domain??' in place of the passive network. Quote Link to comment Share on other sites More sharing options...
Chris A Posted February 19, 2017 Share Posted February 19, 2017 You could ask Dennis (djk)...but he once said that there are only two ways to achieve time alignment: physical alignment (i.e., moving the midrange and tweeter drivers backwards) and digital delay. That's it. I agree. Physical alignment has severe practical issues with HF driver coverage angles in-room and placement of drivers more than 1/4 wavelength from each other at their crossover frequency, and with the resulting appearance of the loudspeakers. Digital delay has no downside. Chris Quote Link to comment Share on other sites More sharing options...
USNRET Posted February 19, 2017 Author Share Posted February 19, 2017 I guess I could give the physical alignment a try just for grins. Too bad I gave my spare tweets away. Any thoughts on how much of a vertical positioning / angle I would need for a 14' listening position? Quote Link to comment Share on other sites More sharing options...
Chris A Posted February 19, 2017 Share Posted February 19, 2017 I'd try 4-6 inches from the top hat top to the centerline of the K-77s. A picture of Marvel's La Scala implementation (i.e., with different tweeters): I'd recommend front-mounting the tweeters to avoid the loss of polar coverage that occurs when mounted on the back side of the baffle. You could also orient the K-77s vertically and get a little better horizontal coverage and give a "slimmer" appearance: Quote Link to comment Share on other sites More sharing options...
USNRET Posted February 19, 2017 Author Share Posted February 19, 2017 Now that is counter-intuitive; tweeter vertical to give better horizontal........ I could do some after market tweets and do some woodwork. Care to post or PM what tweeters I should look at? Quote Link to comment Share on other sites More sharing options...
Chris A Posted February 19, 2017 Share Posted February 19, 2017 The Beyma CP25 I've found requires some EQ (from the JubScala thread): PEQ, f: 8.8kHz, Q: 12, Gain: -3dB PEQ, f: 10.8kHz, Q: 4, Gain: 4dB PEQ, f: 16.8kHz, Q: 4, Gain: 8dB The JBL 2404H predecessor bi-radial tweeter is a bit better, IIRC, but it's discontinued. The Crites CT-125 is a little better, but less sensitive: I haven't looked at the Crites CT-120 ($$), but I'd bet it would sound very good. I don't know if EQ is needed. Chris Quote Link to comment Share on other sites More sharing options...
USNRET Posted February 19, 2017 Author Share Posted February 19, 2017 Chris I edited, cross posted and lost meaning. Which would work with stock? Quote Link to comment Share on other sites More sharing options...
Chris A Posted February 19, 2017 Share Posted February 19, 2017 I saw it, and edited, too. See above. Quote Link to comment Share on other sites More sharing options...
No.4 Posted February 19, 2017 Share Posted February 19, 2017 Sorry for the crumby photo, but there are the DE-120s hiding behind those horns. I do not have measurements but they sound much better to me than the Ct-125 they replaced. Also moving the tweeters back makes these a totally different speaker, in a very good way! 1 Quote Link to comment Share on other sites More sharing options...
Schu Posted February 20, 2017 Share Posted February 20, 2017 I was under the impression that the later klipsch cross overs reversed phase in the HF section to help mimic alignment? I am still looking for a way to bi-amp (tube/class D) without going full digital XO... I have what I would consider two really great amo sections to use, but the unwillingness to buy another technology to accomplish the feat is holding me back. I looked into using a passive to control the gain at the LF section while running the HF section off a tube amp all thru the stock AL-4 Quote Link to comment Share on other sites More sharing options...
Marvel Posted February 20, 2017 Share Posted February 20, 2017 Mike, the driver on my tweeter in the same as Bob's ct125, but with an Eminence horn. I've also tried a Yamaha compression driver with similar results. Never took any measurements though. The Yamaha probably needed eq on the high end. Bruce Quote Link to comment Share on other sites More sharing options...
Chris A Posted February 20, 2017 Share Posted February 20, 2017 12 hours ago, Schu said: I was under the impression that the later klipsch cross overs reversed phase in the HF section to help mimic alignment? I believe that you're referring to "phase alignment" (i.e., multiples of 360 phase alignment at the center crossover frequency). Klipsch has been doing phase alignment of its crossovers/balancing networks/drivers/horns apparently from the beginning. The problem is that phase alignment doesn't do much for loudspeaker impulse response and also timbre shift of the loudspeaker due to time misalignments. Once you clean up time alignment of drivers/horns/crossover networks, the sound is crisp and neutral sounding. Quote Link to comment Share on other sites More sharing options...
Schu Posted February 20, 2017 Share Posted February 20, 2017 what are the differences between "phase" alignment... and a simple physical misalignment? a physical misalignment IS a phase misalignment is it not? or is it a Pulse misalignment? Quote Link to comment Share on other sites More sharing options...
cincymat Posted March 3, 2017 Share Posted March 3, 2017 On 2/20/2017 at 10:55 AM, Chris A said: I believe that you're referring to "phase alignment" (i.e., multiples of 360 phase alignment at the center crossover frequency). Klipsch has been doing phase alignment of its crossovers/balancing networks/drivers/horns apparently from the beginning. The problem is that phase alignment doesn't do much for loudspeaker impulse response and also timbre shift of the loudspeaker due to time misalignments. Once you clean up time alignment of drivers/horns/crossover networks, the sound is crisp and neutral sounding. I've done the physical alignment of the tweeter driver with the squawker driver. Chris is correct that the sound is cleaner, crisper, and more neutral. It also seems to pull the sound stage up from the floor just a bit. See the photo Chris posted above (Bruce's La Scalas?) that is basically what I did. Mark Quote Link to comment Share on other sites More sharing options...
Chris A Posted March 3, 2017 Share Posted March 3, 2017 On 2/20/2017 at 3:32 PM, Schu said: what are the differences between "phase" alignment... and a simple physical misalignment? a physical misalignment IS a phase misalignment is it not? or is it a Pulse misalignment? Time alignment and physical alignment are equivalent (i.e., time alignment via moving the drivers to be coincident in time as viewed from their frontal on-axis direction). You can also achieve time alignment using a digital crossover to delay the driver that is ahead of the other driver(s). Phase alignment generally implies that you don't have time alignment of drivers, but that if you measure the relative time misalignment of the driver that's further away from you, it will be exactly one or more integer wavelengths behind the leading driver, but only at the center frequency between the two drivers' crossover frequency. All other frequencies in the interference band between the two (or more) drivers will have relative phase/time alignment errors. The idea of phase alignment is to hide time alignment errors to the greatest extent possible. Chris Quote Link to comment Share on other sites More sharing options...
JohnA Posted March 4, 2017 Share Posted March 4, 2017 On 2/19/2017 at 6:02 PM, Chris A said: I'd try 4-6 inches from the top hat top to the centerline of the K-77s. A picture of Marvel's La Scala implementation (i.e., with different tweeters): I'd recommend front-mounting the tweeters to avoid the loss of polar coverage that occurs when mounted on the back side of the baffle. You could also orient the K-77s vertically and get a little better horizontal coverage and give a "slimmer" appearance: Long axis vertical only works below 4k Hz. Poor image, but it is all I have. Quote Link to comment Share on other sites More sharing options...
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