Murphy's Corner Line Array project

[audio2design]

I always thought that the more sources of sound you have in different poles of a room mode the less seat to seat variance you have and at a certain number of sources even the effect of the room mode is smoothed out entirely.

I think we are saying the same thing sort of. I am just saying that even with reflections you don't the full line array pattern at 100Hz but not that critical. Add subs.

 

[audio2design]

@ppataki how are you doing equalization to compensate for the high center to center distance at high frequencies?

 

[audio2design]

When I get some free time, I am going to put more thought into the exact implementation I will do with mine. I have no intention of building a curved unit, but I am thinking about the feasibility of how many distinct banks I could have per speaker. I am almost tempted to distribute a digital signal and design mini 1-2 channel, processor/DAC/amp board. A discussion for another thread though. I don't want to take away from the ops great build!

Gave it more thought. Definitely going digital and modular. For another thread once I get started.

 

[bigjacko]

Thanks for your input Wesayso!

I've simmed the CBT using the same driver I have in my straight array, it suffers from way more combing even after his form of volume shading and bending the array. Not an option I would choose for a driver that size. It would require much smaller high frequency drivers. I would never use the volume shading though, it is throwing away one of the true benefits of arrays.

If I understand right, is frequency shading make each driver playing with different frequency, and volume shading make each driver play different volume? You seems to like frequency shading more because it makes less combing issue. Why is volume shading throwing away a true benefit of array?

A full comparison of a frequency shaded array vs an unshaded array to show the difference in combing effects.
The frequency shading need not be complicated, but it does require some shifting of groups for best effects. With an even number of drivers, like @ppataki has, it can even be simpler (and more effective) than my 5x5 driver groups.

Is the one with more high frequency combing in power and DI graph CBT array?

 

[fluid]

Why is volume shading throwing away a true benefit of array?

Line arrays are limited in SPL potential at the top and bottom of their responses but very efficient in the middle. Amplitude shading throws that efficiency gain away.

 

[audio2design]

Line arrays are limited in SPL potential at the top and bottom of their responses but very efficient in the middle. Amplitude shading throws that efficiency gain away.

If you attempt with a full range yes, but if you use a tweeter for the top end then no. Bottom end ditto. You have lots of surface area but no excursion. Better to use a sub.

 

[fluid]

Quite possibly but then the speaker starts to bear no relation to the one this thread is about. Having built and listened to one of those there is a lot of good qualities about it. Adding woofers and tweeters might seem like sensible options but integration without compromising those good qualities is not such a simple task.

 

[audio2design]

UOTE="fluid, post: 1060385, member: 30766"]
Quite possibly but then the speaker starts to bear no relation to the one this thread is about. Having built and listened to one of those there is a lot of good qualities about it. Adding woofers and tweeters might seem like sensible options but integration without compromising those good qualities is not such a simple task.
[/QUOTE]

Except you already are going to experience frequency issues and effectively non line array operation as frequency goes up due to the distance between the effective radiator area of each speaker. Less issues crossing over to tweeters and having a shorter tweeter array

 

[fluid]

In practical use I don't agree with your comments. There are trade offs and compromises to either choice. What is best, easiest or right can always be argued. I didn't expect to like the full range array as much as I did. I sold my LX521 system and kept the array. With the right positioning and tuning they make great stereo music speakers.

 

[ppataki]

@ppataki how are you doing equalization to compensate for the high center to center distance at high frequencies?

I am using Dirac Live 3 to linearize the response + Pultec EQ (Waves PuigTech) to fine-tune the final sound to my taste
I have made some measurements already, planning to post them today

 

[ppataki]

At last the speakers are in their final place!
I have made some preliminary measurements but take it with a pinch of salt since the insulation of the cabinet is not yet finished, there is a pretty severe air leakage going on (that will be fixed either today or tomorrow)

Measurements were made at main listening position using UMIK-1 with REW (1/12 smoothing) at 75dB

Frequency response:

The blue one is the original, non-compensated curve - pretty horrid, as expected
The peach is the curve that Dirac Live 3 produced when I set the target curve to be totally flat - getting there
And finally the highlighted one is a result of tweaking the target curve in Dirac + using Pultec EQ (Waves PuigTech) to further fine-tune the sound
As you can see the highs have to be compensated very heavily, eating up like 15dB of amp power
I have some pretty nasty room modes between 50-60 and 70-90Hz - I can compensate those but at the expense of increased ringing as you will see below

T60M curves for the same

I will have to decide if I prefer the more flat sound in the lows with increased ringing vs less perfect low-end with significantly lower ringing

Waterfall for the linearized Dirac + Pultec measurement:

Wavelet diagram for the same:

Step response for the same:

Impulse response for the same:

IR zoomed in:

Distortion curves - these look pretty bad but I suspect that the air leakage might have some impact here:

And finally, a video that shows how it looks and how it sounds:

New video by Peter Pataki

photos.app.goo.gl

Here are some additional thoughts:
- dynamics are extremely good
- transients are excellent (really 'fast' sound)
- stage is wide, but precise but obviously not too deep
- phantom center is a bit less forward vs my previous setup
- sound is no less detailed vs my previous setup - both micro and macrodynamics are excellent
- sub is definitely not needed for music, there is plenty of energy down to below 25Hz
- even for movies I will not consider using a sub, however I need to say that the impact is a bit less compared to my previous setup where I had two 12" subs too (however the lows seem to be more 'detailed' with the line arrays)
- footprint is extremely small (the speakers are tall but they consume virtually no space since they are in the corners) - WAF just went over the roof, at least in my case
- very heavy EQ compensation is needed so take that into account when choosing an amp for such a project
- sound is kind of filling the whole room, anywhere you go, stand, sit, lie, etc. you hear almost the same
- my listening spot is 325cm away but even if I go to the other end of the room (720cm) volume does not seem to decrease (see above point)

The next steps will be to fix the insulation then I will post a new set of measurements in a few weeks' time once the drivers had their 'break-in'

 

[DanielT]

At last the speakers are in their final place!
I have made some preliminary measurements but take it with a pinch of salt since the insulation of the cabinet is not yet finished, there is a pretty severe air leakage going on (that will be fixed either today or tomorrow)

Measurements were made at main listening position using UMIK-1 with REW (1/12 smoothing) at 75dB

Frequency response:
View attachment 181197

The blue one is the original, non-compensated curve - pretty horrid, as expected
The peach is the curve that Dirac Live 3 produced when I set the target curve to be totally flat - getting there
And finally the highlighted one is a result of tweaking the target curve in Dirac + using Pultec EQ (Waves PuigTech) to further fine-tune the sound
As you can see the highs have to be compensated very heavily, eating up like 15dB of amp power
I have some pretty nasty room modes between 50-60 and 70-90Hz - I can compensate those but at the expense of increased ringing as you will see below

T60M curves for the same

View attachment 181199

I will have to decide if I prefer the more flat sound in the lows with increased ringing vs less perfect low-end with significantly lower ringing

Waterfall for the linearized Dirac + Pultec measurement:
View attachment 181200

Wavelet diagram for the same:
View attachment 181208

Step response for the same:
View attachment 181203

Impulse response for the same:
View attachment 181204

IR zoomed in:
View attachment 181205

Distortion curves - these look pretty bad but I suspect that the air leakage might have some impact here:
View attachment 181207

And finally, a video that shows how it looks and how it sounds:

New video by Peter Pataki

photos.app.goo.gl

Here are some additional thoughts:
- dynamics are extremely good
- transients are excellent (really 'fast' sound)
- stage is wide, but precise but obviously not too deep
- phantom center is a bit less forward vs my previous setup
- sound is no less detailed vs my previous setup - both micro and macrodynamics are excellent
- sub is definitely not needed for music, there is plenty of energy down to below 25Hz
- even for movies I will not consider using a sub, however I need to say that the impact is a bit less compared to my previous setup where I had two 12" subs too (however the lows seem to be more 'detailed' with the line arrays)
- footprint is extremely small (the speakers are tall but they consume virtually no space since they are in the corners) - WAF just went over the roof, at least in my case
- very heavy EQ compensation is needed so take that into account when choosing an amp for such a project
- sound is kind of filling the whole room, anywhere you go, stand, sit, lie, etc. you hear almost the same
- my listening spot is 325cm away but even if I go to the other end of the room (720cm) volume does not seem to decrease (see above point)

The next steps will be to fix the insulation then I will post a new set of measurements in a few weeks' time once the drivers had their 'break-in'

Superb, very well done! Congratulations.

This is exciting. You seem happy, that's the most important thing. And you seem to have had fun during your DIY trip. Informative, for me at least, to partake of. The sound clearly seems very good and appealing according to your description!

What I was stuck on was this you said:As you can see the highs have to be compensated very heavily, eating up like 15dB of amp power

15 dB is quite a lot. Hm, then it's time to calculate how much power the amplifier needs. Will you have more amplifiers? Divide the signal? Multiple
amps? Or how did you think there? Maybe you already wrote about it in the thread? Then I missed it and apologize for asking now.

Another thing I wonder is, now you have calculated a nominal value of Ohm for the speakers, but hm wonder how it is with so many drivers regarding fluctuations in impedance? They should be .... hm I do not know more even than ? ... Nop I do not know. But it does not matter if you have amplifiers that fix low loads.

How much power does an amplifier need with this type of range of dynamic music

Feel free to use this calculator. Add sensitivity to the speaker and then tell which effect you have chosen and why. Weigh in that you want some headroom. http://www.mh-audio.nl/Calculators/REAP.html You can select music from this list. Or something else, but in that case tell us how you...

audiosciencereview.com

Edit:
Thanks for the video! Looks yummy. They seem to have potential, if I may say so. (attached image screenshot from your video)

 

[Wesayso]

Congrats on first sound, ppataki! A marvelous moment I'm sure.
Keep working on figuring out that distortion problem, it shouldn't have to be that high. I hope fixing the leak will help.
Also keep an eye on any automated EQ, as there could be a tendency to over-correct (which even may sound nasty).
At lower frequencies (sub ~80 Hz) you can determine which of the two arrays plays which parts best, to get a very nice
sum of both at the listening area, while neither array is working too hard to get there.

Take the time to work on the overall tonal balance. Try a few different room curves to learn what you like.
I've worked on that for quite a while and ended up with an in-room curve that looked a lot like the "trained listeners"
curve below. After finding that similarity it has become my base target from which I tweak to my liking:

Above ~300 Hz try to get the left and right curve to match as close as possible. A few manual tweaks here and there help.

 

[Wesayso]

Thanks for your input Wesayso!

If I understand right, is frequency shading make each driver playing with different frequency, and volume shading make each driver play different volume? You seems to like frequency shading more because it makes less combing issue. Why is volume shading throwing away a true benefit of array?

Answered already by Fluid, but volume shading is limiting the number of drivers that contribute at mid and lower frequencies.
It is what makes a line array sound effortless i.m.h.o. Every driver only has to do a small part, especially in mid frequencies where much of our music lives.
The frequency shading is limiting the outer drivers at certain frequencies. But it lets all drivers playing the low or low/mid frequencies, depending on their position within the array.

See the above power distribution of my 5 groups of 5 drivers. The top straight line is 5 drivers that play full range.
Below that is a group (2 drivers placed above and 3 below the before mentioned 5 drivers) that is gradually letting go above 2 KHz.
Then there's two groups of 5 drivers each that act almost alike and start to contribute less and less above 300 Hz.
Left is one group of 5 drivers that still contributes to bass notes but contributes almost nothing above 200 Hz.

Is the one with more high frequency combing in power and DI graph CBT array?

This one?

That is a comparison of a straight full range driver line array without shading and with frequency shading applied.
I haven't shown the CBT, but with drivers this large (about 3.5" in my case) there wouldn't be much point in doing so.

 

[Wesayso]

One more thing ppataki... for your own sanity. Get an SPL meter. It doesn't have to be expensive. Once you get distortion low enough, it's very easy to play (go) louder than you realize. You'll only notice it if you want to start a conversation .

To avoid that, I use JRiver as my mediaplayer and let that average the SPL level of the songs. It is using the R128 algorithm to make every song 'appear' to be equally loud. (once it has every song analyzed) Before I started using that I've ran the arrays at outrageous levels on some songs.
(without really realizing it)

 

[ppataki]

Superb, very well done! Congratulations.

This is exciting. You seem happy, that's the most important thing. And you seem to have had fun during your DIY trip. Informative, for me at least, to partake of. The sound clearly seems very good and appealing according to your description!

What I was stuck on was this you said:As you can see the highs have to be compensated very heavily, eating up like 15dB of amp power

15 dB is quite a lot. Hm, then it's time to calculate how much power the amplifier needs. Will you have more amplifiers? Divide the signal? Multiple
amps? Or how did you think there? Maybe you already wrote about it in the thread? Then I missed it and apologize for asking now.

Another thing I wonder is, now you have calculated a nominal value of Ohm for the speakers, but hm wonder how it is with so many drivers regarding fluctuations in impedance? They should be .... hm I do not know more even than ? ... Nop I do not know. But it does not matter if you have amplifiers that fix low loads.

How much power does an amplifier need with this type of range of dynamic music

Feel free to use this calculator. Add sensitivity to the speaker and then tell which effect you have chosen and why. Weigh in that you want some headroom. http://www.mh-audio.nl/Calculators/REAP.html You can select music from this list. Or something else, but in that case tell us how you...

audiosciencereview.com

Edit:
Thanks for the video! Looks yummy. They seem to have potential, if I may say so. (attached image screenshot from your video)

I am currently driving these beasts with a pair of Hypex NC250MPs
Those can output 200W at 4 ohm - I believe that it shall be sufficient given that the total sensitivity of the system is around 96dB/1m/channel
Also as far as I know line arrays drop at 3dB/m instead of 6dB/m
Having said that and knowing myself I might upgrade to a more beefy one once Topping or SMSL finally releases such a model (for example a 400W version of the PA5 would be awesome)

 

[abdo123]

Don’t worry too much about the boost in higher frequencies, energy there is almost always low in music anyway.

Are there plans in the future to extend it to the ceiling?

 

[ppataki]

One more thing ppataki... for your own sanity. Get an SPL meter. It doesn't have to be expensive. Once you get distortion low enough, it's very easy to play (go) louder than you realize. You'll only notice it if you want to start a conversation .

To avoid that, I use JRiver as my mediaplayer and let that average the SPL level of the songs. It is using the R128 algorithm to make every song 'appear' to be equally loud. (once it has every song analyzed) Before I started using that I've ran the arrays at outrageous levels on some songs.
(without really realizing it)

Yes, you are totally right - I forgot to mention this in my summary. The volume slider in Jriver became too hot!

 

[ppataki]

Don’t worry too much about the boost in higher frequencies, energy there is almost always low in music anyway.

Are there plans in the future to extend it to the ceiling?

I cannot really comment on that right now....I would like to wait at least a month to draw a final conclusion on these ones and then I will make up my mind about where to go next
Right now what I have in mind is to replace my rear speakers with a truncated line array to match with the new fronts (but again, we shall see)

+ there is another project that one of my friends is building: https://www.audiosciencereview.com/...t-using-markaudio-chr-120.29142/#post-1017155
Very much looking forward to that too!!

 

[Ericglo]

In practical use I don't agree with your comments. There are trade offs and compromises to either choice. What is best, easiest or right can always be argued. I didn't expect to like the full range array as much as I did. I sold my LX521 system and kept the array. With the right positioning and tuning they make great stereo music speakers.

IIRC Don Keele thought that the issues would be to great not to have very close spacing of the tweeters. I believe Rick Craig said that is why he chose the cheap small tweeters for the original CBT36.

I am not sure if Rick or someone else persuaded him to try the full range Daytons. After trying and testing, IIRC he found the issues in practice were not that big of a deal.

I didn't realize that you had a Linkwitz LX521. I have read a lot of owners consider that their end game speaker.