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Murphy's Corner Line Array project
- Thread starter ppataki
- Start date
DanielT
Major Contributor
I'm talking about general terms. Not aimed at any specific person. I'm very well aware of Wesayso's own DIY.
DanielT
Major Contributor
What a life it was about a screwdriver. I just mentioned it in passing. Also mentioned that there may be a fault in a driver itself. What did ppataki write?
I have replaced one driver that had a strange mechanical noise.....
Edit:
You can do as you please. I just pointed out that it's sad if you sit there with your 50 drivers and it turns out that one of them has something wrong with it. Then it's time to order ... a new one. It's just cumbersome and time consuming. No quantity discount, shipping cost only one driver and so on.
I have replaced one driver that had a strange mechanical noise.....
Edit:
You can do as you please. I just pointed out that it's sad if you sit there with your 50 drivers and it turns out that one of them has something wrong with it. Then it's time to order ... a new one. It's just cumbersome and time consuming. No quantity discount, shipping cost only one driver and so on.
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Wesayso
Active Member
No worries, Daniel... it was the way you worded it that seemed funny to me, like we could get casualties beside the drivers themselves.
Not really serious about it.
While building my arrays I had no faulty drivers (at that time). I always run impedance checks before mounting them but even after mounting the drivers something can (and often will) go wrong.
After about 7 years of use, (the driver age was close to 10 years) some drivers failed on me. Corrosion being the cause, probably happened a bit sooner than usual due to (a year of) storage in a damp garage while we were renovating our home. Those were Vifa/Peerless TC9 FD18-08 drivers.
I will replace all of them with the Scan Speak 10F 8414G10 very soon.
Not really serious about it.
While building my arrays I had no faulty drivers (at that time). I always run impedance checks before mounting them but even after mounting the drivers something can (and often will) go wrong.
After about 7 years of use, (the driver age was close to 10 years) some drivers failed on me. Corrosion being the cause, probably happened a bit sooner than usual due to (a year of) storage in a damp garage while we were renovating our home. Those were Vifa/Peerless TC9 FD18-08 drivers.
I will replace all of them with the Scan Speak 10F 8414G10 very soon.
DanielT
Major Contributor
Wtf ...corrosion!No worries, Daniel... it was the way you worded it that seemed funny to me, like we could get casualties beside the drivers themselves.
Not really serious about it.
While building my arrays I had no faulty drivers (at that time). I always run impedance checks before mounting them but even after mounting the drivers something can (and often will) go wrong.
After about 7 years of use, (the driver age was close to 10 years) some drivers failed on me. Corrosion being the cause, probably happened a bit sooner than usual due to (a year of) storage in a damp garage while we were renovating our home. Those were Vifa/Peerless TC9 FD18-08 drivers.
I will replace all of them with the Scan Speak 10F 8414G10 very soon.
Good luck with the new DIY project!
Edit:
storage in a steam garage ... well that may well be the reason. I can imagine.
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Wesayso
Active Member
Yes, indeed... Wtf...
Similar to how some mid range drivers from Scan Speak started to fail (some random hits):
https://www.diyaudio.com/community/...nspeak-mid-range-drivers.205127/#post-3336456
https://www.diyaudio.com/community/threads/scan-speak-13m-8636-sudden-death.310858/
Scan Speak was the original developer of this specific Vifa/Peerless line so it's no surprise to have it happen on one of those models as well.
Scan Speak have acknowledged this defect, they have traced it back to the glue used and changed the type of glue to prevent this from happening on drivers produced ever since. Sadly Tymphany wasn't available for comments. That made me choose for the Scan Speak as a viable substitute.
I have operated 5 of the 6 drivers that failed on me to make sure what the problem was. They all suffered the same faith. This connection is positioned right below the dust cap and the voice coil being made of aluminium wire makes it a difficult fix (if at all possible).
P.S. We (the Dutch) also use salt on our roads in Winter times. I know (have seen) what it can do.
Similar to how some mid range drivers from Scan Speak started to fail (some random hits):
https://www.diyaudio.com/community/...nspeak-mid-range-drivers.205127/#post-3336456
https://www.diyaudio.com/community/threads/scan-speak-13m-8636-sudden-death.310858/
Scan Speak was the original developer of this specific Vifa/Peerless line so it's no surprise to have it happen on one of those models as well.
Scan Speak have acknowledged this defect, they have traced it back to the glue used and changed the type of glue to prevent this from happening on drivers produced ever since. Sadly Tymphany wasn't available for comments. That made me choose for the Scan Speak as a viable substitute.
I have operated 5 of the 6 drivers that failed on me to make sure what the problem was. They all suffered the same faith. This connection is positioned right below the dust cap and the voice coil being made of aluminium wire makes it a difficult fix (if at all possible).
P.S. We (the Dutch) also use salt on our roads in Winter times. I know (have seen) what it can do
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hollis
Active Member
- Joined
- Sep 3, 2018
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- 86
We built 3x pairs of MCLA, so 150 ND90 drivers plus a couple dozen spares. Tested them upon arrival and found zero bad copies. Way cool.
John L Murphy
Member
This CBT graphic shows a far-field representation of a short line array with no reflections. The CBT system is shown with a (hidden) ground plane reflection providing the bottom half of the system. The in-room floor and ceiling reflections invalidate the response shown here. Note that CBT assumes only ONE reflection from the (implied) floor. Tapering the corner line array (either geometrically or via delay) would spoil the MCLA response. The CBT approach is designed assuming half space loading by the a base plane (floor or ground) with no other reflections. Imagine adding the ceiling reflection. If you include the ceiling reflection in the simulation it would seriously change the CBT response to something "different". Adding the floor and ceiling reflections to the MCLA turns it into an infinitely long array (approximately) with gentle amplitude tapering due to the repeated reflections. In the room you cannot move out of the near-field of the MCLA.Looking sweet! Super jealous right now!
You could even (if the technology allows in the future) assign a delay to each driver so you would get a constant beam transducer instead.
Sorry to be so late... I'm just catching up on this thread. I stopped getting notices of posts for some reason.
Regards,
John
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John L Murphy
Member
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
<<snip>>
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'
ppataki,
GOOD WORK!
They look great and I fully agree with your assessment of the sound. Enclosure filling will only make them sound better.
Congratulations on getting them up and running. Enjoy the music!
Best Regards,
John
Glad to see you back on the forum!
As far as i remember only the half arc CBT designs (Where the arc is cut in half, like most JBL commercial products) require (or assume) half space loading, the graph i shared is depicting a full arc so i don't think this applies. Please correct me if i missed something.
I think it's worth to experiment with both designs considering how cheap and available digital processing is. Everytime I listened to regular line arrays i was often too distracted by the high frequency non-linearity. I have no idea how the MCLA would sound since it's effectively an infinitely long line array, perhaps this is a non-issue in this case.
- Thread Starter
- #152
The comparison in that graphic would be fair if the application was a free field flown array as is common for sound reinforcement, the CBT would have to be a full arc to function.
The graphic shows why there are little to no straight flown arrays.
For use at home inside a room the situation changes (as John points out above) the floor and ceiling surfaces work to improve the response of an infinite array. The floor is necessary for a half arc CBT to function but the effect of the ceiling reflection on it's pattern is not included in the graphic. So it is of no use in comparing how the systems behave inside a room. The CBT is a great concept but that graphic is easily misinterpreted.
David Smith has returned to diyaudio in retirement and posted the start of what should be an interesting thread
https://www.diyaudio.com/community/...-through-simple-modeling.388279/#post-7071864
It's always worth experimenting, what is a "regular" line array?
The comparison in that graphic would be fair if the application was a free field flown array as is common for sound reinforcement, the CBT would have to be a full arc to function.
The graphic shows why there are little to no straight flown arrays.
For use at home inside a room the situation changes (as John points out above) the floor and ceiling surfaces work to improve the response of an infinite array. The floor is necessary for a half arc CBT to function but the effect
David Smith has returned to diyaudio in retirement and posted the start of what should be an interesting thread
https://www.diyaudio.com/community/...-through-simple-modeling.388279/#post-7071864
It's always worth experimenting, what is a "regular" line array?
Ones that are not infinitely long
Sure that is implied as you heard it, but there are a wide variety of configurations that could be called a line array, without knowing which, makes it hard to know why you felt there was high frequency non linearity, which in of itself could mean many things.Ones that are not infinitely long
Usually when i move my head around i can audibly hear the response changing.
Things can also jump at you, get localised from behind for some reason or simply stand at your shoulders. Things I wouldn’t experience outside linearrays.
Massive installations at live venues. The very typical stuff.
Typical of live venues but completely different to the type of arrays that work well in the home.
And what type would that be?