Okay I ordered the Driverack PA2 
but following DBX Driverack 260 auction and waiting for the t.racks FIR DSP 408 to be available again.
but following DBX Driverack 260 auction and waiting for the t.racks FIR DSP 408 to be available again.The specs of the dual 15" JBL say "1350 W (5400 W peak)" so for each of the two 15" it would be 675W (2700W peak) right? What would be the optimal power of the amp per channel? When I had the Behringer NX-6000D going half way was already LOUD and in most cases we won't need so much. The PLX 2402 was 300 and I could use it for the JBL AC18/95. So I'm still looking for a decent amp for both JBL ASB6125.
Thank you for the picture but I cannot make complete sense of it. It looks like the back of the CD is embedded in the box and protrudes outwards. But the JBL 2450H as Hifi connectors at the back and I need to connect them to Speakon sockets. Hence they can't be outside but must be inside the box with the Speakon socket facing out. How about cutting a hole in a board with the diamater of the CD at point A (see below) and mounting that board inside the box? There are also holes at point B but they have no thread and I have no clue what they are for?
The idea would be to all EQing and other adjustments from the tablet so all we would need is a mixer instead of a huge FOH area.
I have no idea what it does to be honest. But let's say you're deciding between DBX Driverack PA2, DBX Driverack 260 (used) and t.racks FIR DSP 408 all about the same price, you wouldn't hesitate to buy the t.racks FIR? It won't run on Mac or iOS though which may not be a dealbreaker.
I will, thanks for the link. BTW: they always talk about rooms. But I assume they're also suitable for outside venues?
Do you know how this support usually looks like? Would the board with cutout at point A (see above) be the correct approach?
The processing your speakers need for optimal performance and protection should be setup before the system ever sees an event, this processing should not change at each venue. If the system needs any additional EQ at an event it should be easily done on the mixer.
I'd buy the DR260 because of the routing limitations in the PA models(can only do stereo configs), but any FIR based unit will have a current processor inside versus a 10-20yr old processor found in the Driveracks.
You're still thinking you can use these tools at venues, I promise you this won't be the case most of the time. But to answer your question the "Room" part of the name simply indicates the designer was thinking more home audio applications, but the software doesn't know if the speakers are in a room or outside.. the operator has to know how to decipher the data the software presents.
There are lots of possibilities, you can find metal brackets that mount between the driver and horn, this drivers appears to have mounting eyelets so you could do something as simple as bolt a small L bracket to one of those holes and then attach that to a block of wood that sits under the driver.
Yes, you have divided by 2 correctly.
Around 3000-6000 watts peak into 4ohms would allow the JBL ASB6125 to reach their peak output potential, which could damage hearing of anyone near the speakers not wearing hearing protection.
The NX-6000D can do ~3000 watts peak into 4 ohms, or 1600 watts into 8ohms per channel.
It has useful power indicator LED lights:
"Limit" illuminates when ~ 3000 watts peak into four ohms is reached,
The amp will limit power to under that if the input exceeds 0dBu (.775volts) with the input volume control turned fully clockwise.
Most mixers can exceed that level by 20dB or more.
"-3dB" illuminates ~ 1500 watts (half power).
"-6dB illuminates ~ 750 watts (1/4 power).
"-40dB" illuminates ~3 watts.
Your JBL ASB6125 2x15" sensitivity is around 100dB SPL (sound pressure level) 1/w1m outdoors.
100dB 1watt
110dB 10watts
120dB 100watts
130dB 1000watts
133dB 2000watts
136dB 4000watts
Outdoors, each doubling of distance reduces level by 6dB. Indoors, levels are room dependent.
Outdoors, at 10 meters, 100watts (+20dB) would be required to reach the 1w/1m level.
The picture showed exactly that, a circular support hole the diameter of the EV DH1A compression driver at point A cut into a piece of plywood.
The "holes at point B" attach the 2350's 1.5" to 2" throat adapter.
Without the adapter, the driver would be a 2450SL, a 1.5" exit driver.
Horns are made to fit specific throat diameters.
Art
Last edited:
Ok then the Mac/iOS issue won't be a deal breaker. I probably return the PA2 and get the t.racks FIR.
True but wouldn't it adjust everything based on the measurement microphone, e.g. it will "hear" no reflective surfaces so it will adjust accordingly or is this to naive? We won't need acoustics of an opera hall just avoiding things are too far off.
Not bad but I wonder why it's used for home cinema i.e. listed under Cinema Sound > Immersive Rooms > ASB6125
That's interesting and a bit confusing. So at 10 meters away to have 100dB (which is quite loud), we only need 100W? Also your dB > Watt chart shows extreme diminishing returns beyond 1000W. Should I not scope the amp to this level, i.e. a little above 1000W per channel?
Thanks, I didn't know the difference between these. But I actually meant the holes as seen below. Do they have any purpose? They don't have threads, just holes.
Yes the mic input is all it has to work with, the problem is the processing doesn't know why the response it measures has non linearities and the only tool it has to correct that is to boost or cut with EQ. If the mic happens to be positioned in a node where there is cancellation at a certain frequency due to different arrival times from the speakers, no amount of EQ will fix this the only thing that does affect it it moving the speakers or the mic. Same applies to phase and time alignment issues through the crossover region, these cannot be fixed with EQ. Bottom line is developing effective corrective processing for a loudspeaker system requires a lot of manual hands on testing and experimentation, it's not something that has been sucessfully automated yet.
The listing has everything from 2-way 8"/HF, to four-way 2x15", 4x8" + 4"/HF.
"Large format and 3D cinemas require perfect coverage in every seat of the auditorium, wide dynamic range and extended bandwidth, as well as inaudible levels of distortion. Digital soundtracks require sound systems for premier auditoriums that can accurately reproduce the sound exactly as recorded."
An experienced contractor will pick what is appropriate for the room size and SPL requirements.
Yes, that's what the specifications say.
You are confused because you are not yet conversant with the inverse square law and the concept of the decibel, a unit used to measure the intensity of a sound or the power level of an electrical signal by comparing it with a given level on a logarithmic scale.
The decibel and inverse square law are as basic to sound as the 12 note octave scale is to western music.
The decibel concept is now 100 years old, I only became aware of it about 50 years ago (-3dB)
What you call "diminishing returns" is inherent in the logarithmic nature of sound propagation and perception.
If you decide you don't want to use the +6dB headroom available above 1000w (4000watts), no need to buy an amp with that "scope".
The extra +6dB allows twice the coverage distance.
Then again, if you don't want to use that output, you could get by with two 15" rather than four..
They can be used to attach shackles or support brackets similar to this JBL cinema system:
Have fun, good luck!
Art