EV Dx38 active xover questions/observations

[Coytee]

Anyone: It seems as though the MASTER delay on my active is set on a minimum of 1.9 ms. not the delay between drivers, but the master delay. Meaning, anything I have on like a dvd will be out of sync with the visuals. I made the left channel something like 500 ms delayed relative to the right channel... it was kind of cool playing with these settings. Screws with your head but what the heck. Now, back to the delay...

First off, CAN I somehow get the MASTER delay to zero and if I do, then do I need to be concerned with the delays used on the drivers (set at 2271 us)

Item 2 for Dr. WHO.

You asked somewhere if you had different settings memorized in this thing, could you swap back/forth with no delay on sound. It seems the answer there is YES. I've been tinkering with it and prior to saving the data, as I've been playing with the delay and stuff, it will make the changes live. I then swapped between two different program files and the change seemed to be instant.

I think that'll make it easier, if we want to try different settings and get a closer A/B on them!

Finally figured out how to save a program into a different slot. Seems I'd been saving everything into the same slot over & over...[:@] Live & learn.

[]

[Edgar]

Anyone:  It seems as though the MASTER delay on my active is set on a minimum of 1.9 ms.  not the delay between drivers, but the master delay. 

First off, CAN I somehow get the MASTER delay to zero and if I do, then do I need to be concerned with the delays used on the drivers (set at 2271 us)

It doesn't say so in the manual, but I suspect that the 1.927 mSec is the inherent delay through the unit. This is the amount of delay through the A/D converters, processing paths, and D/A converters, and cannot be reduced.

I'm not certain exactly how much delay is necessary before lipsync problems become intolerable, but I understand the general rule of thumb to be that it is on the order of 30 mSec. And it's much less noticeable when the audio is delayed relative to the video than it is the other way around. It seems our brains are accustomed to hearing sounds after seeing the events that cause them, because the speed of sound is so slow compared to the speed of light.

Greg

[Coytee]

As another side comment, I was having some kind of sound make it to a speaker in spite of:

A- turning the signal down on the Dx38 on that channel

B-turning the Dx38 master signal down

Seems this thing has a R/L input and right next to those, has a mirrored output so you can feed identical signal into another unit and daisy chain multiple units together.

I've discovered that the channel volumes and master volume work MUCH better when a specific driver is NOT plugged into the mirrored output, but into it's PROPER channel slot...

sigh.

[:$]

[DrWho]

lol Coytee, have you read through the entire manual yet? What ever happened to using the settings Roy suggested? []

And thanks for checking into that AB thing.

[Coytee]

lol Coytee, have you read through the entire manual yet? What ever happened to using the settings Roy suggested? []

And thanks for checking into that AB thing.

Read the manual? it was the first thing I did!!!! [A]

Actually, though I've not read it per se', I HAVE perused through it. Beyond that, I usually just jump into something and then read about what I can't figure out. I would have never made it through brain surgery school... well... perhaps I would have, it's the patients that would have had some issues...

As far as Roy's settings, I don't get your question unless the following is your angle.

I AM using Roy's numbers, however, he can't supply me the numer to use when I'm using amps of different input sensativities. He supplied me the forumla for figuring out how to balance them and I now have those 'handicap' numbers. What I'm planning on doing is putting his settings into the unit under several different names (IE, amp configurations) so if I am to swap out amp for another I can already have the amp configured inside the DX-38. Just scroll to it's name.

Even if I don't ever do that (swap amps), playing around like this is how I'll learn more about the unit. I'll explore what makes it tick and try to notice any changes made by my blind, random and ignorant tinkering (the very reason my "patients" might have had some residual issues had I gone to brain surgery school [:$])

"hey teacher...what's this part (holds up in raised hand for all to see)

"uh... that's the frontal lobe and people need that to prevent them from acting like an ape"

"hmm... so I should perhaps try to put it back and pretend I never removed it??"

"perhaps"

[Al Klappenberger]

Richard,

I am courious about the delay numbers Roy suggested to you. There should be a different delay number for the high and for the low, that is for above and below the crossover. I would like to know what that difference is. It would seem to me that would be the actual delay time from the woofer drivers to the plane of the high frequency driver. That time difference whould put the two drivers in time with each other.

Al k.

[mikebse2a3]

Richard,

I am courious about the delay numbers Roy suggested to you. There should be a different delay number for the high and for the low, that is for above and below the crossover. I would like to know what that difference is. It would seem to me that would be the actual delay time from the woofer drivers to the plane of the high frequency driver. That time difference whould put the two drivers in time with each other.

Al k.

Al k.

The High Frequency Horn/Driver (Output Channels Modules) has a (Delay Setting of 2271 micro seconds) versus the Low frequency Horn (Output Channels Modules Setting of 0 ms).

The 1.9ms Delay is the minimum setting of the (Master Delay Modules) in the Input Channels Section of the EV Dx38.

mike tn[]

[PrestonTom]

Coytee,

Congratulations again on getting the Jubilees.

After showing the picture to my girlfriend, my K-Horns (neatly tucked into the corners) now seem small. Not necessarily small enough, but you have done a great service for the rest of us - thank you. Actually maybe a picture of a Hedlund Horn would be helpful .....

Regarding the A/B comparison of the time alignment:

The implementation may be simple but the interpretation would not be. At the crossover point if the signal in that frequency band is equal in level and equal in phase between the two drivers (perfect time alignment and no usual phase shift that you would get from a passive crossover), then the there will be a bump in the amplitude spectrum. This will be up to 6 dB in SPL. Conversely if the two signal were perfectly aligned, but out of phase at the crossover region, then there would be decrease in the amplitude spectrum. This is nothing new and is one reason why a 90 deg releative phase shift is used (usually set by the order of the filters), since that combination will give a relatively flat spectrum given the various assumptions (yes, I am assuming a measure on axis etc).

I bring this up since the time alsignment is "aligning" in time and not in phase. So that a constant time delay will produce a linear shift in phase as a function of frequency (not a constant phase shift). The consequence is that some frequencies may add up roughly "in phase" will others will add up roughly "out of phase" and cases in between. This crude analysis suggests that if the crossover slopes are shallow (broad spectral overlap), then your time re-allignment may also be introducing a different amplitude spectrum. The unaligned version will also suffer from the is problem, but its "coloration" will differ from the "aligned" version.

In essence this is why an A/B comparison may be confounded with changes in the amplitude spectrum. Incidentally, it is also why steep crossover slopes are so intriguing.

I have been very careful not to mention the issue of the possibility of an audible "group delay". This in part is motivating Dr Who's question about the A/B comparision. However, and I think ALK will perhaps agree, when you bring up the issue of group delay, then people at first get confused and then they get hostile. So let's stay way from that.

So, yes I am also interested in the audubility of that A/B comparison, but can it be done with a "steepish" filter.

Good luck and I freely admit that I am extremely envious,

-Tom

[Coytee]

Actually maybe a picture of a Hedlund Horn would be helpful .....

Don't have a picture of a Hedlund Horn and wouldn't know one if it honked me [6]

I DO have a couple pictures of the Maxel posters everyone has been yacking about though...

I beem debating on where to hang them...

Also, for a lot of the intellectual stuff you said, you ought to direct that towards Mike, or at least someone who better understands it than I. I swear, it seems like everyone on this board is either an engineer, engineer or perhaps, an engineer [] aren't there any other dummies like me around? []

Mike can answer the technical questions and I'll answer the "how to handle the wife questions" of course, you're going to have to get married first []

[Coytee]

Really, I'm simply trying to hide them

[Coytee]

Think she'll buy it?

[sfogg]

"Anyone: It seems as though the MASTER delay on my active is set on a

minimum of 1.9 ms. not the delay between drivers, but the master

delay. Meaning, anything I have on like a dvd will be out of sync with

the visuals. "

Don't sweat it, that is nothing.... the same as if your speakers were simply 2 feet further away from you. You have more delay then that just from the time it takes the sound leaving your speakers to reach your ears.

Depending upon your display (basically if it is progressive scan or not) you may have considerably more video processing delay already. Typically the audio needs to be delayed to account for video processing, not vice versa.

Shawn

[Edgar]

This is nothing new and is one reason why a 90 deg releative phase shift is used (usually set by the order of the filters), since that combination will give a relatively flat spectrum given the various assumptions.

The 90 degree relative phase shift is a characteristic of Butterworth crossovers. If a properly-implemented Linkwitz-Riley crossover is used, then the lowpass and highpass sections are in-phase at all frequencies, and each has half-amplitude (-6 dB) at the crossover frequency. In such a situation, perfect time alignment leads to perfect sum-to-allpass frequency response in the crossover, and any remaining anomalies are due to the drivers themselves.

I designed the crossovers in the Dx38's great-granddaddy, the Merlin ISP-100, so I know that EV knows how to implement Linkwitz-Riley crossovers properly. I no longer have any affiliation with EV, so I can only hope that they continued the tradition in the Dx38.

I have been very careful not to mention the issue of the possibility of an audible "group delay".

Group delay is only an issue in a modulated system, which a loudspeaker is not (or should not be).

Greg

[Al Klappenberger]

Richard,

Thanks for the delay number. That will allow me to do a computer sumation of both outputs of any passive crossover I might design to see how the sounds from the two drivers will add up at the crossover frequency. If I could just get the complex impedance of the woofer I could take a stab at an ES network for it. All I would need then would be the frequency respnse of the high frequency driver and horn to design the CD equalizer. The rated Zo and voice coil inductance of the drivers in that woofer would get the cmplex zo number close enough to get started. I could take a stab at it anyhow. It looks like Roy is simply not going to help us.

Al k.

[mas]

According the the Klipsch Jubilee spec sheet, the acoustical origin offsets are

0 (reference) - LF

3.5 ms - MF

4.6 ms - HF

PS. Regarding the ~1.9 ms 'master' propagation delay - there will be some propagation delay that you cannot eliminate. Unfortunately everything does not happen in zero (or negative[] ) time! But 1.9 ms is not allot of time! It should not result in everything appearing to be a badly dubbed martial arts flick!

On the other hand, if you inverted the phase and fed the delay back into the signal ...you might be able to cancel time...let me find my HP-48...[]

[bodcaw boy]

This is nothing new and is one reason why a 90 deg releative phase shift is used (usually set by the order of the filters), since that combination will give a relatively flat spectrum given the various assumptions.

The 90 degree relative phase shift is a characteristic of Butterworth crossovers. If a properly-implemented Linkwitz-Riley crossover is used, then the lowpass and highpass sections are in-phase at all frequencies, and each has half-amplitude (-6 dB) at the crossover frequency. In such a situation, perfect time alignment leads to perfect sum-to-allpass frequency response in the crossover, and any remaining anomalies are due to the drivers themselves. I designed the crossovers in the Dx38's great-granddaddy, the Merlin ISP-100, so I know that EV knows how to implement Linkwitz-Riley crossovers properly. I no longer have any affiliation with EV, so I can only hope that they continued the tradition in the Dx38.

I have been very careful not to mention the issue of the possibility of an audible "group delay".

Group delay is only an issue in a modulated system, which a loudspeaker is not (or should not be). Greg

edgarapoe,

so you had something to do with the models for the filters in the 38 if they were grandfathered in? that is cool!! i really like this unit and have heard about the merlin as well.

berryboy roy

[bodcaw boy]

Richard,

Thanks for the delay number. That will allow me to do a computer sumation of both outputs of any passive crossover I might design to see how the sounds from the two drivers will add up at the crossover frequency. If I could just get the complex impedance of the woofer I could take a stab at an ES network for it. All I would need then would be the frequency respnse of the high frequency driver and horn to design the CD equalizer. The rated Zo and voice coil inductance of the drivers in that woofer would get the cmplex zo number close enough to get started. I could take a stab at it anyhow. It looks like Roy is simply not going to help us.

Al k.

full of absolutes.....tisk, tisk.....

berryboy roy

[Edgar]

so you had something to do with the models for the filters in the 38 if they were grandfathered in?  that is cool!!  i really like this unit and have heard about the merlin as well. 

I was just one of many who contributed to a long line of digital processors in the Altec Lansing, ElectroVoice, Merlin, Klark-Teknik, and Dynacord lines. The DSP firmware in the Merlin was my personal responsibility, but I borrowed some from my predecessors, and others borrowed from me for later products. After I left, I think that all DSP development went to the Dynacord group in Germany, but they had all of my code and, glancing at some of the features of the Dx38 I wouldn't be surprised if they're still using some of it. Many of the built-in configurations of the Dx38 are dead-ringers for what I did in the Merlin.

Greg

[mikebse2a3]

so you had something to do with the models for the filters in the 38 if they were grandfathered in? that is cool!! i really like this unit and have heard about the merlin as well.

I was just one of many who contributed to a long line of digital processors in the Altec Lansing, ElectroVoice, Merlin, Klark-Teknik, and Dynacord lines. The DSP firmware in the Merlin was my personal responsibility, but I borrowed some from my predecessors, and others borrowed from me for later products. After I left, I think that all DSP development went to the Dynacord group in Germany, but they had all of my code and, glancing at some of the features of the Dx38 I wouldn't be surprised if they're still using some of it. Many of the built-in configurations of the Dx38 are dead-ringers for what I did in the Merlin. Greg

Hi Edgar

If any of it is from your past design then all I can say is great job! This Units Functions are very well thought out and easy to use!

mike tn[]

[Edgar]

To the extent that anything I did influenced the parts that you like, thank you.

Greg