BillFitzmaurice.info

LelandCrooks wrote:I really like the grilles. Nicely done.

+1. A question, though. Do you plan to glue fabric or foam as a backer to the grilles?

DJPhatman wrote:

LelandCrooks wrote:I really like the grilles. Nicely done.

+1. A question, though. Do you plan to glue fabric or foam as a backer to the grilles?

Thanks fellas!

I hadn't planned on a backer, just a bit of adhesive foam on each cleat for anti-rattle.

ctmullins wrote:

DJPhatman wrote:

LelandCrooks wrote:I really like the grilles. Nicely done.

+1. A question, though. Do you plan to glue fabric or foam as a backer to the grilles?

Thanks fellas!

I hadn't planned on a backer, just a bit of adhesive foam on each cleat for anti-rattle.

Looks way better with the foam backer. Just use A/C filter foam (for window units). You can get it at Wal-Mart. Cut it to size, spray the grill with adhesive, then put the foam on. Stack up however many grills you have, put a board on top of 'em, then add some weight. After a few hours, they are ready to install.

Thanks, I'll check into it. As long as I don't actually have to go to Wal-Mart...

ctmullins wrote:Thanks, I'll check into it. As long as I don't actually have to go to Wal-Mart...

Or, you can go to a HVAC company and pay 5 times as much.

Hardware store. They might even have the bulk roll and cut it to length. I know I used to.

All Duratex'ed and corners and top hats installed. Have one more melded array to make, then it's wiring time!

Decided to go forward with the two straight-array cabs. Got the first one finished up (except for the grille) this afternoon. Smoke tested it with Spotify running through the Aux In on my little GK MB200.



All of the tweeters work, the woofer works, both Speakons work, and a tone sweep shows no obvious issues at the crossover point. Yay!

Two straight-array cabs done! I hooked them up along with one T39 and listened to various tracks for a couple hours last night. Played around with EQ some too, just to get a feel for them. Very mid-forward, like the Jacks. Very shy on the low end, no surprise there. The very top end I thought was also a bit shy, not sure if that's due to the lower sensitivity of just six piezos instead of twelve? Nothing a little EQ can't fix. LOUD!



The two melded cabs will be done soon, then I can drag 'em outside and try some RTA.

Check your wiring scheme at both the filters and the tweeters themselves. If they are still a little "shy in the high", change the array wiring to 3 parallel pairs of series, or even parallel them all. But, I would do some testing first, just to make sure all are working. Also, reverse the polarity on the array. If you search around, there's also a recommendation by Bill to move a resistor, I think. Bill?

Thanks my friend, great suggestions. I checked Bill's plans, and the resistor mod is designed to reduce output from 2.5k to 5k, so that's not going to help.

I suspect another culprit altogether, though - I have a Behringer XR18 in my rack, running off an Apple Airport Express. Since I have the Express, I have an audio cable running from its analog audio output into the Aux in (channels 17/18) on the XR18. That way I can play prerecorded music over AirPlay.

I did a quick Google search just now, and discovered this article in which the frequency response (and lots of other nerdy things) of the Express' AirPlay is measured - the graphs show a high-freq rolloff starting at about 3k, winding up 1.5db down at 20k. Not terrible, but it might be contributing. I need to test with my source physically cabled into the XR18.

First melded cab assembled and successfully tested. I do think the melded array has a bit more shimmer in the top end, again, makes sense having twice as many tweeters.

I tried gluing the diffuser on but it came off after a few days. So I deviated from the plans. Very slightly! I drilled a top and bottom hole in the array and screwed the diffuser on. I like having a firm mechanical fastener here.

I thought about something very similar. Just be sure to use something at every array joint to absorb rattling between the diffuser and the array.

Getting back to the flat array, did you confirm all the elements are working, using a paper towel core as a listening tube? There could be a non-working element, or some that are low output, causing your lack of shimmer. Usually, piezos give too much highs, being called bright or harsh.

I did. They're all working, but not all at the same level. One or two are noticeably lower output. Not sure how many spares I have, but I should be able to swap out the elements, right?

I stacked the melded and straight cabs on a pole last night and just played music through them for a couple of hours while I relaxed. With some EQ they sound really good, very detailed. Running both of them I felt like I had enough crisp top end.

Hopefully I'll have time tomorrow to set them up outside and do a pink noise RTA. I don't have a reference mic; I'll just be using the built-in iPhone mic. I know it won't be perfect, but it'll give me something to start with. I already set up a baseline EQ by reversing the SPL chart, and have been tweaking the higher frequencies a bit by ear indoors. We'll see how different outdoors is. It will also be an opportunity to piss off the neighbors by running them wide open for a bit...

This was gratifying.



Ran it as loud as I dared, given the close proximity of elderly neighbors. Wow!