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[Stephen Swaffer]

So a few weeks ago I posted a frustrated rant at "sales engineers."  Learned a few things and ultimately worked with m pastor and said I'll help you with whatever you decide to try.

Now, the Bose Line Array has been avoided.  He was thinking about demoing a JBL that TJ had recommended, but right now we have a QSC K12 on hand to try out.  I was also able to demonstrate some things last night-he felt that our system was not capable of any low end, but when you sweep through the audio freqs with the signal generator on the QU its obvious what we do and do not have.  Playing some white noise made it clear where our coverage is-and the coverage patternis very desirable-hitting the seating area and dropping off before the walls lsmost perfectly-which is my main reason for even resisting the change-as I do like the sound of the K12.

I would like to do the besyt I can with the existing and see what we have, but I am not sure of the correct crossover freq.  And, if we do go with the K12s, I am wondering about their coverage compared to the existing.  The info I have on this cluster is that it is EV a TL60DX box over "909/MR994" horns.  Those numbers are off of a handrawn block diagram-and I assume ae the driver/horn or horn/driver and I also assume a partial part number as a search draws a blank.  Any idea's?

The K12 is listed at 75 deg-which I am thinking will be too narrow to use just 2 to cover the area we need to-but if I can find the specs on the existing I can get  better idea.

One other, perhaps off-the-wall, question-one complaint pastor has is uneven coverage from the piano.  We have a 9 ft grand in a 50 X 100 foot room-the piano itself has plenty of volume on its side of the auditorium.  If I went with a 2 speaker K12 cluster and fed from L & R would it be reasonable to pan just the piano to help with that-how effective would it be?

[Andrew Makinson]

The info I have on this cluster is that it is EV a TL60DX box over "909/MR994" horns.  Those numbers are off of a handrawn block diagram-and I assume ae the driver/horn or horn/driver and I also assume a partial part number as a search draws a blank.  Any idea's?

Altec Lansing mr994a with a 909 driver.  The pattern is specced as 90*x40* for one horn.
Some pictures would be helpful if you want any more answers.

[Stephen Swaffer]

Altec Lansing mr994a with a 909 driver.  The pattern is specced as 90*x40* for one horn.
Some pictures would be helpful if you want any more answers.

Here is a pic of the cluster, as well as 2 from the platform looking out at the auditorium.  I had posted one of these a couple years ago and the consesus was to leave alone.  I was surprised recently when the pastor suddenly wanted to change.  I am Ok with that as long as we don't go backwards.

I suspect some of the reluctance on the part of some to answer is that I would be better off bringing in a consultant-I have fought to make that happen and had talked both with Tom Young and Doug Fowler about doing so.  I suspect some also would prefer to see a pro come in for rigging-and I agree, though I do have a man that manufacturs overhead conveyors for poultry processing-I suspect if he can hang a dynamic load like that, he can probably hang speakers successfully.

I have learned enough on here to make intelligent arguements that I can demonstrate-and I think that will prevent a complete fail-and maybe we will end up in not so bad a shape.  Pastor understand enough to know that the 90 X 40 pattern doesn't match up well with the 75 deg conical of the K12.  I was able to demonstrate with whote noise the accuracy of the coverage of the existing.  He also thought the "horns" had no low end.  Starting a sweep at the low end with the QU32 signal generator proved otherwise-and walking off axis while the K12 was playing music showed clearly how LF is not as directional as HF-so it was better than debating merits.

My biggest question mark with this system is what the typical crossover should be-just a ball park?

[Jim Thorn]

I serviced eight high school auditorium systems that used large horns splayed to cover various audience areas, crossed over to one or two reflex bass boxes, similar to your church's system.  Whether the bass boxes had 12-inch or 15-inch drivers, the crossover was usually at 800 Hz.  I'm pretty sure that's roughly the lowest crossover frequency the compression driver and horn combination would reliably handle.
There is likely to be a line-level crossover in the amp rack -- you may be able to read knob settings, or labels on plug-in modules, to confirm the crossover point.

Regards,
Jim Thorn

Here is a pic of the cluster, as well as 2 from the platform looking out at the auditorium.  I had posted one of these a couple years ago and the consesus was to leave alone.  I was surprised recently when the pastor suddenly wanted to change.  I am Ok with that as long as we don't go backwards.

I suspect some of the reluctance on the part of some to answer is that I would be better off bringing in a consultant-I have fought to make that happen and had talked both with Tom Young and Doug Fowler about doing so.  I suspect some also would prefer to see a pro come in for rigging-and I agree, though I do have a man that manufacturs overhead conveyors for poultry processing-I suspect if he can hang a dynamic load like that, he can probably hang speakers successfully.

I have learned enough on here to make intelligent arguements that I can demonstrate-and I think that will prevent a complete fail-and maybe we will end up in not so bad a shape.  Pastor understand enough to know that the 90 X 40 pattern doesn't match up well with the 75 deg conical of the K12.  I was able to demonstrate with whote noise the accuracy of the coverage of the existing.  He also thought the "horns" had no low end.  Starting a sweep at the low end with the QU32 signal generator proved otherwise-and walking off axis while the K12 was playing music showed clearly how LF is not as directional as HF-so it was better than debating merits.

My biggest question mark with this system is what the typical crossover should be-just a ball park?

[Stephen Swaffer]

I serviced eight high school auditorium systems that used large horns splayed to cover various audience areas, crossed over to one or two reflex bass boxes, similar to your church's system.  Whether the bass boxes had 12-inch or 15-inch drivers, the crossover was usually at 800 Hz.  I'm pretty sure that's roughly the lowest crossover frequency the compression driver and horn combination would reliably handle.
There is likely to be a line-level crossover in the amp rack -- you may be able to read knob settings, or labels on plug-in modules, to confirm the crossover point.

Regards,
Jim Thorn

There was a Peavey electronic crossover-but someone ( can I plead the 5th?) lost the original settings.  Actually, the battery died and there was no hard copy.  At the time (and still) I was irritated with the installer.  The install was done prior to my arrival and they spent quite a lot on the install-and for the most part it was well done.  My beef was with the mic snake, no doubt existing, that they left.  It had a hodge podge of capacitors and other ill conceived intereference "killing" components such that every snake channel sounded different.  It would have taken very little effort to fix that one huge issue with the system (a pair of wire cutters and half an hour?).  If that's all the pride they take in an install, no need for me to call them again.

[Stephen Swaffer]

I serviced eight high school auditorium systems that used large horns splayed to cover various audience areas, crossed over to one or two reflex bass boxes, similar to your church's system.  Whether the bass boxes had 12-inch or 15-inch drivers, the crossover was usually at 800 Hz.  I'm pretty sure that's roughly the lowest crossover frequency the compression driver and horn combination would reliably handle.
There is likely to be a line-level crossover in the amp rack -- you may be able to read knob settings, or labels on plug-in modules, to confirm the crossover point.

Regards,
Jim Thorn

So, is the preferred setup the lowest frequency thecompression driver/horn will handle or are there other considerations?

[Ivan Beaver]

So, is the preferred setup the lowest frequency thecompression driver/horn will handle or are there other considerations?

There are A LOT of other "it depends" when looking at how low a compression driver can/should be operated.

As you go lower, the power capacity goes down.

Also the size of the horn, the expansion rate of the horn etc will determine a low point.

Next up for consideration is the size of the woofer.  As the woofer size goes up, the lower the compression driver crossover should be to properly have comparable patterns to avoid the "Christmas tree" cover pattern

[Robert Healey]

My biggest question mark with this system is what the typical crossover should be-just a ball park?

The usable low frequency limit on your horns is 500 Hz, and it has good horizontal control down to that frequency. The 909 driver also goes down to 500 Hz.

You can cross over higher, but the TL606 won't have the same pattern control of the horn at that point. It gets significantly narrower the higher you go. 500 Hz is below the speech intelligibility region so it is a pretty good crossover point for speech reinforcement.

Ivan is suggesting matching directivity at the crossover point, but you have two horns and a single LF box so you should be OK there. The TL606 has 160 degrees of coverage at 500Hz, and given the splay of your horns it looks like that's about what you have in the HF as well.

If everything in the cluster still works and you replace the crossover with a new DSP, the cluster should sound pretty good. Well tuned and adjusted, it would likely outperform a K12.

[George Dougherty]

If the pastor feels that in general operation there isn't enough LF capability ithe system then it should be a relatively simple matter to add a true sub to the system.  It's one thing to sweep and hear content down low.  It's quite another to feel the impact of LF content either live or recorded. 

Danley as well as others make some wonderful compact boxes that could be flown with the existing cluster to provide even bass coverage.  Ivan was an incredible help when I worked on the design for my own church and the results have been phenomenal.

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