Anyone time align their Khorns with active over/delay and then go back to passive covers?

[Travis In Austin]

"Depending on the passive network and the electrical phase of the driver, you can only get rid of a small portion of that time delay."

This quote from Mr. Z above was always my understanding.

How much, if any time delay can you get from a passive? I thought there were a couple of ways to get some time delay but it was limited, costly, and there were major tradeoffs?

[Chris A]

Yes.  You can series all-pass networks to get more delay, but anything more than perhaps 360 degrees of phase delay is pushing it. Delays that are inherent in multi-way horn loudspeakers as well as the need for correction of controlled directivity horn frequency response via parametric EQ and shelving filters--these are the two key reasons why digital active crossovers are so important to horn lovers to get that real inherent magic out of them. 

 

Once you hear the sensitivity of human hearing to very small delays between drivers/horns, you'll never forget what it sounds like. 

 

Once you correct those delays, you'll never forget the sound experience that ensues...

 

Chris

Edited December 2, 2015 by Chris A

[Chris A]

I know this is in other threads but what is the time differential between the bass and midrange/tweeter on a Khorn? Is it 7ms?

 

I believe it's more like 6 ms (in fact).  The Richard Heyser review of the Khorn in 1986 said 7+ ms, but Greg Oshiro measured 6 ms, and published his results on this forum in terms of all the settings needed to convert to an active digital crossover on your Khorns.

 

Chris

Edited December 2, 2015 by Chris A

[Quiet_Hollow]

FWIW - My La Scala are now time-aligned. Using MCACC Pro I can quickly A/B between the original and adjusted signal.
 
Suffice to say, I will not be going back. In ten years of ownership, hands-down it's the best they've ever sounded.
 

Once you correct those delays, you'll never forget the sound experience that ensues...

Agreed. 

 

P.S. - So does Frazier, Danley, Vandersteen...and most planar/ribbon owners.

 

[pzannucci]

 

To each his own based on their ability to handle the complexity, tuning, and cost of the active setup.

 

I've seen this repeated elsewhere: I strongly disagree.  You should try it instead of listening to naysayers.

 

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YMMV.

 

Chris

 

For me, not daunting, for others, yes.  The settings on the subject for multi-amping is available but the ability to tweak for the room is a big plus on the active configuration of course.

 

This is not as easy as having a passive network where you just hook up speaker cables.  How many people still hook speakers up out of phase and you'd want them to set up a multi-amp configuration?

 

To me a good bass horn's sound the most natural (unless you have a lot of radiating area with woofers).The low/mid cross, low cross (read long midrange horn) to tweeter time delays and being forced to multi-amp has moved me away from larger horn/bass horn systems.

[Chris A]

For me, not daunting, for others, yes.

 

Peter,

 

That's the way that I understood your remark.  Some folks do have more trouble than others, but for those that are seeking better sound, I figure that they'll learn what they need to learn, or get help.  I figure that active crossovers are lot less daunting to hook up properly and dialing in the settings than first learning to use a tablet computer or a smart phone loading and using some fancy app.

 

Chris

[Coytee]

Active digital crossovers just aren't difficult to set up and use.  Like anything else, there may be more knowledgeable users than others, but that doesn't stop anyone from learning what they need to know. Active digital crossovers aren't even close to the difficultly in some of the topics above.

 

There must be a nail somewhere in this thread because this comment just hit it on the top!!

 

I'm proof positive that it doesn't have to be daunting to go active.   I went active 'overnight'.  Yeah, I had some issues and cross wiring my XLR wires backwards didn't help me get off to a good start!!  If I can make it through, just about anyone can if they want to.

[DMH]

I've also gone active without too much expense or difficulty getting it all set up. In fact, it was very enjoyable learning how to do it. I'm definitely not an expert and probably never will be. I admit that I've a lot more to learn and at times it's a pain. But the reward in sound quality more than makes up for any frustration. Going active even saved money by increasing the quality of my stock Belle's to such an extent that I won't be needing expensive upgrades. And I did it for less than the cost of a custom built set of passive crossovers.      

[Travis In Austin]

For me, not daunting, for others, yes.

Peter,

That's the way that I understood your remark. Some folks do have more trouble than others, but for those that are seeking better sound, I figure that they'll learn what they need to learn, or get help. I figure that active crossovers are lot less daunting to hook up properly and dialing in the settings than first learning to use a tablet computer or a smart phone loading and using some fancy app.

Chris

I agree with that completely, IF, AND ONLY IF, you have the settings from somebody WHO KNOWS WHAT THEY ARE DOING.

The numbers we had to start with on Junes, Cornscallas, jubescallas, were done by somebody who knows what he is doing.

A novice, like me, can figure out how to enter the numbers and end up with extraordinary sound.

A nivice starting from scratch, even if he knew the proper crossovet points, would be going around in curcles for years trying to figure out what the best set u0 was.

[jwgorman]

Apparently I have to move to Texas to hang out with all the cool kids! I guess I want to at least hear a time-aligned khorn setup before I die. 

This is gonna be just like muscle cars, target pistols and harleys...no end to the maddness!!!! My wife is a saint. 

[jcmusic]

 

I don't use an active setup but, I do have my khorns time aligned. (Mid and Tweeters) I used the ALK Universal for years and loved it, now I use a custom made network that is basically that exact same thing as the Universal except with much better parts... Also have my room EQ'ed and treated...

Canyonman,

 

What do you mean by time aligned for the mid and tweeter?  Are you talking the tweeter is at the same position as the mid-range driver? 

 

With the passive network you have to get rid of the time delay (or rather delay) for the mid and tweeter to each other and the 7 ft pathway for the bass horn.  Depending on the passive network and the electrical phase of the driver, you can only get rid of a small portion of that time delay.

 

 

The passive network implies that you will have a certain amount of eq and rolloff built into the network itself.  For a lot of people trying to simulate this roll off and eq in an active network is very painful.  Also what will sound good to one person may not sound good to another.  To each his own based on their ability to handle the complexity, tuning, and cost of the active setup.

 

What I mean is the tweeter and mid drivers are aligned physically, my tweeters are mounted on top of my khorns so I just kept pushing them back towards the mid driver until the measurements showed them almost perfectly aligned. If I remember right they are with in 60us of each other, and anything 100us or better is real good... Using REW to measure I was able to achieve great results with room treatment and EQing...

[DrWho]

...if so, then I'd really recommend a better active digital crossover than the one you identified

 

 

Ditto that. DBX Driverack has no place in the home. I don't even like it for pro audio use.

[Quiet_Hollow]

If I remember right they are with in 60us of each other, and anything 100us or better is real good...

I hope you meant "milli" seconds... Otherwise we'd be backing up the tweeter into the adjacent property.

 

MCACC consistently measured my La Scala at 1.5 ms (~51.4 cm) between the K77 and K55M across the front three.

[DrWho]

I was just thinking that the audible characteristics of time alignment and tighter system equalization can be heard with something entry level like the Driverack. Sure, other aspects of the sound are getting sacrificed in the process, but you can isolate those by listening to a bypassed processor through your passive xover. Once you know what your gear is doing to the sound, then you can remove the passive xover and implement an active solution. You can even toggle the time-alignment in/out to see how much that matters compared to the other EQ aspects. It's a free experiment since you already have the Driverack...just go into it trying to understand what can be adjusted, rather than hoping for an ideal audiophile solution right off the bat.

 

If you hear things you like and are willing to chase them, then it's just a matter of picking a better sounding active solution....but maybe you're one of them hardcore analog types that can't stand the sound of digital anything in the signal path. We all have different tastes when it comes to the artifacts that bother us. It's not like the active xover is a billion times better - it's one of those more subtle things that I personally only notice during dedicated listening. With background music I don't think I've ever noticed. The one instrument that sticks out the most to me is the snare drum. Lack of alignment has a blurry, less crisp sound to it. When aligned, there's a lifelike crispness that just clicks into place. A similar thing happens to busier passages of music - things just sound a bit more congested / vague when unaligned, and then a soft clarity snaps into place when aligned. One other thought - you're only going to notice it on source material with dominant frequency content that spans across the xover frequency.

[jcmusic]

 

If I remember right they are with in 60us of each other, and anything 100us or better is real good...

I hope you meant "milli" seconds... Otherwise we'd be backing up the tweeter into the adjacent property.

 

MCACC consistently measured my La Scala at 1.5 ms (~51.4 cm) between the K77 and K55M across the front three.

 

No I did not mean ms!!! uS stands for microseconds or 1 millionth of a second!!!

[Quiet_Hollow]

No I did not mean ms!!! uS stands for microseconds or 1 millionth of a second!!!

No argument from me on the definition of a microsecond.

 

What I was trying to say, kindly, was that your delay measurement is off. 

 

60μs is only 0.8 inches, which is not enough.

[DrWho]

Quiet - he moved his tweeter back until it measured within 60us, or is that not the confusion anymore?

 

I typically target being within +/-15 degrees of phase, and sometimes use that to help tilt the polar bubble a bit at the xover frequency. At 6kHz you're looking at 167 uS for 360 degrees of phase, so 60uS is about 130 degrees of phase error. Does one of the drivers have inverted polarity? Even with inverted polarity you're still off by 50 degrees. The phase of the driver/horn combination along with the passive xover is definitely introducing its own phase into the system. Perhaps that explains some of the delta? Although with REW you should be able to see the phase response too. The numbers it reports for absolute delay are skewed due to the band-limiting of the signals, but that gets into all sorts of nasty complicated math. When dialing in time, I maximize the frequency overlap of the two drivers, then invert one driver and adjust the delay until I get the biggest possible null at my desired xover frequency. This also necessitates amplitude matching the two drive units. Once I know where the null is, then you can un-invert the driver and you should see +6dB output at that frequency...then you dial in the xover frequency slopes. I don't even look at the time delay reported by REW (other than to make sure I'm not 360 degrees off).

 

At the end of the day, one should try to target +/-7uS accuracy for a 6kHz xover frequency...

[Quiet_Hollow]

Quiet - he moved his tweeter back until it measured within 60us, or is that not the confusion anymore?

Ah ha. Got it now. Thanks for the clarification.   

[jwgorman]

I was just thinking that the audible characteristics of time alignment and tighter system equalization can be heard with something entry level like the Driverack. Sure, other aspects of the sound are getting sacrificed in the process, but you can isolate those by listening to a bypassed processor through your passive xover. Once you know what your gear is doing to the sound, then you can remove the passive xover and implement an active solution. You can even toggle the time-alignment in/out to see how much that matters compared to the other EQ aspects. It's a free experiment since you already have the Driverack...just go into it trying to understand what can be adjusted, rather than hoping for an ideal audiophile solution right off the bat.

 

If you hear things you like and are willing to chase them, then it's just a matter of picking a better sounding active solution....but maybe you're one of them hardcore analog types that can't stand the sound of digital anything in the signal path. We all have different tastes when it comes to the artifacts that bother us. It's not like the active xover is a billion times better - it's one of those more subtle things that I personally only notice during dedicated listening. With background music I don't think I've ever noticed. The one instrument that sticks out the most to me is the snare drum. Lack of alignment has a blurry, less crisp sound to it. When aligned, there's a lifelike crispness that just clicks into place. A similar thing happens to busier passages of music - things just sound a bit more congested / vague when unaligned, and then a soft clarity snaps into place when aligned. One other thought - you're only going to notice it on source material with dominant frequency content that spans across the xover frequency.

 

I will have my son help me lug my rack downstairs and experiment with it. I've noticed the snare in live music too as far as dialing in the FOH. I appreciate the advice. 

[jcmusic]

Quiet - he moved his tweeter back until it measured within 60us, or is that not the confusion anymore?

 

I typically target being within +/-15 degrees of phase, and sometimes use that to help tilt the polar bubble a bit at the xover frequency. At 6kHz you're looking at 167 uS for 360 degrees of phase, so 60uS is about 130 degrees of phase error. Does one of the drivers have inverted polarity? Even with inverted polarity you're still off by 50 degrees. The phase of the driver/horn combination along with the passive xover is definitely introducing its own phase into the system. Perhaps that explains some of the delta? Although with REW you should be able to see the phase response too. The numbers it reports for absolute delay are skewed due to the band-limiting of the signals, but that gets into all sorts of nasty complicated math. When dialing in time, I maximize the frequency overlap of the two drivers, then invert one driver and adjust the delay until I get the biggest possible null at my desired xover frequency. This also necessitates amplitude matching the two drive units. Once I know where the null is, then you can un-invert the driver and you should see +6dB output at that frequency...then you dial in the xover frequency slopes. I don't even look at the time delay reported by REW (other than to make sure I'm not 360 degrees off).

 

At the end of the day, one should try to target +/-7uS accuracy for a 6kHz xover frequency...

Thanks Mike,

Saved me from all that typing, LOL!!! Excellent explaination and very helpful. So you are saying I should try and get to +/- 7uS at the 6Khz? What and how much benefit would this provide?