Check your builds after time

Helpful hints on how to build 'em, and where to get the stuff you need.
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Grant Bunter
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Check your builds after time

#1 Post by Grant Bunter »

It's been quite some time since build for some of Bill's designs I use.
My rig has done thousands of miles in harsh Australian conditions, heat, dust, rough roads.

I've been in a process over the last few months to work out some of the items that require attention, and have started to refurbish bits and pieces that need attention, so, I thought I would share a little.

The cabs:
These radiata pine based builds have really held up well. Wipe down with a damp cloth to remove dust as required, and a paint touchup when the dings get to noticeable.

The components:
Just yesterday, I had to pull out a 3012lf to see why it was non functional mid set up at gig (it had performed flawlessly 5 days before).
30 miles later...
Turned out the -ve lead to the driver in the chamber was at best, just connected, despite locking washers on the binding posts.
If you open up your subs to re tension your screws or bolts, please, pull the driver out at that time and check the wiring, refresh your sealing strips and torque that baby down again.

Melded arrays:
I'd noticed a drop off in one side of HF on my DR250's. A good mate sent me some new GW's he had spare, so I hopped into it.
Module off, filters appeared and tested pristine, so not the problem.

Turns out about half of the elements in the melded array tested either low, or not working.
I need the cab in a hurry, so just replaced the non workers, diagnosed with the tube to the ear method and a 3K tone.
I must have missed the one that was so close to being gone, hence distorting even at low volume.
I actually burned one new one out with too much heat when soldering, so beware! Use a heatsink on the element side of the tab.

I will have to dive into that module again, but fixing 10 was like night and day.

I've also had some issues over the last 6 months with leads. I'm gradually changing over to Neutrik and Canare, done all my stage drops.
Every time I have a failed lead it is inspected and tested. Hardly ever find a problem, or failed upon testing, so my advice is: dump it.
It is just not worth the grief it gives you.

I've had some issues with power supplies in (1 each of 2) DEQ2496 and DCX 2496's. It's a known problem, I've been doing a lot of reading on it, and maybe $50 in parts each should sort them out, and address some of the other issues these have.
Backups for my driverack, mostly relegated to analogue rigs, so haven't blown out a gig for me.

If you think you can save dollars buying older gear, just remember if it's from the 90's, the caps are already 30 years old and about due to give up. Everything I recap now has 105 degree C at least for the power supply, but you can't always do that with some of the control circuits.

Hope you find this helpful, and a timely reminder your gear doesn't look after itself...
Last edited by Grant Bunter on Sat Dec 10, 2022 12:12 am, edited 1 time in total.
Built:
DR 250: x 2 melded array, 2x CD horn, March 2012 plans.
T39's: 4 x 20" KL3010LF , 2 x 28" 3012LF.
WH8: x 6 with melded array wired series/parallel.
Bunter's Audio and Lighting "like"s would be most appreciated...

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Tom Smit
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Location: Sarnia, Ont. Canada

Re: Check your builds after time

#2 Post by Tom Smit »

Grant Bunter wrote: Fri Dec 09, 2022 9:03 pm
If you think you can save dollars buying older gear, just remember if it's from the 90's, the caps are already 30 years old and about due to give up. Everything I recap now has 105 degree C at least for the power supply, but you can't always do that with some of the control circuits.

Hope you find this helpful, and a timely reminder your gear doesn't look after itself...
Some good advice, there, Grant. I'm not understanding what you meant by "105 degree C at least for the power supply". Please explain kind sir.
TomS

Grant Bunter
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Location: Ilfracombe Queensland Australia
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Re: Check your builds after time

#3 Post by Grant Bunter »

Sure thing Tom!

Capacitors are rated for voltage, low ESR and capacitance, but also for X amount of hours at Y operating temperature. Increased operating temperature handling capability comes at a cost, but that cost isn't astronomical.

If you're a manufacturer though, scales of economy may dictate that using 85 degree C rated capacitors is required in order to reduce overhead and maximise profit.
85 deg C caps are fine for most control circuitry, and many of the "better brand" cap makers only make 85 deg C caps.
But that may become a problem in the power supply, where they will also use 85 deg caps, because heat is always a byproduct of converting electricity.
Often caps fail in power supplies for this reason, or, as they begin to fail, the expected voltage isn't supplied, making the unit erratic.

The DCX and DEQ 2496 are both culprits.
So is the SPX 50, SPX 90, SPX90II and the Alesis MEQ230 and to a lesser extent the 3630.
So, I try to use cap brands better suited to power supplies with higher temperature handling, eg Panasonic 105 deg (the specs might be something like 5000 hours at 105 deg C).
On a retail basis I might pay an extra 30 cents for these compared to 85 deg caps.
For a couple of $, or less than a cup of coffee, it just seems to make sense to me on a per unit basis (especially where I live/work).

Hope that's clearer...
Built:
DR 250: x 2 melded array, 2x CD horn, March 2012 plans.
T39's: 4 x 20" KL3010LF , 2 x 28" 3012LF.
WH8: x 6 with melded array wired series/parallel.
Bunter's Audio and Lighting "like"s would be most appreciated...

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Tom Smit
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Joined: Sat Jan 05, 2008 1:24 pm
Location: Sarnia, Ont. Canada

Re: Check your builds after time

#4 Post by Tom Smit »

Oh, Grant, that is waayyyyyy clear. Thanks, for that info. Definitely helpful!
TomS

Keryn O'Shea
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Joined: Sat Jan 26, 2013 5:50 pm
Location: Brisbane, Australia

Re: Check your builds after time

#5 Post by Keryn O'Shea »

Grant Bunter wrote: Fri Dec 09, 2022 9:03 pm Use a heatsink on the element side of the tab.
Nice tip Grant, other than using your tongue, which method works best for you mate?

Also, how often should we be checking driver fasteners?
AT8 14", AT10 19", T30 28" LAB12, T48 36" 3015LF, THT 20" LAB15, SLA 4x3"/4x4", CArray 6x4", TLAH, TLAP, J10 FLat, J12 Flat, OT12 Flat, OT15 CD, SLAP 2x6"/4x6", WH8, DR280 Mld'd, XF210. Next J10L

Grant Bunter
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Joined: Mon Nov 28, 2011 11:12 am
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Re: Check your builds after time

#6 Post by Grant Bunter »

Keryn O'Shea wrote: Thu Jan 05, 2023 2:22 am
Grant Bunter wrote: Fri Dec 09, 2022 9:03 pm Use a heatsink on the element side of the tab.
Nice tip Grant, other than using your tongue, which method works best for you mate?

Also, how often should we be checking driver fasteners?
Cheers Keryn,
I use a straight crile artery forcep as my heatsink, holds it in place while you use 2 hands to solder.

Tightening screws, well i reckon it was 5 years at least since Bruce mentioned it and I still hadn't, so "more often than Grant does"...
Built:
DR 250: x 2 melded array, 2x CD horn, March 2012 plans.
T39's: 4 x 20" KL3010LF , 2 x 28" 3012LF.
WH8: x 6 with melded array wired series/parallel.
Bunter's Audio and Lighting "like"s would be most appreciated...

Grant Bunter
Posts: 6915
Joined: Mon Nov 28, 2011 11:12 am
Location: Ilfracombe Queensland Australia
Contact:

Re: Check your builds after time

#7 Post by Grant Bunter »

Pleased to say another 3 piezo's in the first, previously worked on cab, and 5 in the other, have sorted this out.

This time I didn't guess, I measured. Used the Berry 8000 ref mike into a DEQ2496, using peak meter with mike inserted into each horn mouth to get a reading which was written on the capsule housing, with a 3K test tone.
Then used the tube method again, because there was some obvious distortion that wasn't displayed by the peak meter.

Then replaced any that were distorted, or read less than 95dB.

And, I have to put my hand up for being the cause of the distortion in one capsule.
It's quite obvious that I didn't make sure that the cone was properly seated, so had a gap of roughly 30%. No wonder.
This occurred when I built, so heads up to check that as you go...
Built:
DR 250: x 2 melded array, 2x CD horn, March 2012 plans.
T39's: 4 x 20" KL3010LF , 2 x 28" 3012LF.
WH8: x 6 with melded array wired series/parallel.
Bunter's Audio and Lighting "like"s would be most appreciated...

Grant Bunter
Posts: 6915
Joined: Mon Nov 28, 2011 11:12 am
Location: Ilfracombe Queensland Australia
Contact:

Re: Check your builds after time

#8 Post by Grant Bunter »

Oh, and while the chamber was open, tweaked the screws on the mid drivers.
A couple turned as much as 1/4 of a turn...
Built:
DR 250: x 2 melded array, 2x CD horn, March 2012 plans.
T39's: 4 x 20" KL3010LF , 2 x 28" 3012LF.
WH8: x 6 with melded array wired series/parallel.
Bunter's Audio and Lighting "like"s would be most appreciated...

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Seth
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Location: Sacramento, California, USA
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Re: Check your builds after time

#9 Post by Seth »

Enjoyed the update, Grant. Always neat hearing about problems and learning good solutions :thumbsup:
Build in process - 2 WH6, one Alpha 6a loaded, one PRV Audio 6MB250-NDY loaded

Two 2x6 shorty SLA Pro's
One T39, 16", 3012LF loaded
Tall AutoTuba, 20" wide, 2x 8" MCM 55-2421
TruckTuba, 8½" wide, 2x 8" MCM 55-2421

Grant Bunter
Posts: 6915
Joined: Mon Nov 28, 2011 11:12 am
Location: Ilfracombe Queensland Australia
Contact:

Re: Check your builds after time

#10 Post by Grant Bunter »

I thought this should be added in this thread too.
I wrote it, in part, as a response in this thread:
viewtopic.php?p=293947#p293947

I'm revisiting my melded arrays in my DR250's at present. It's 11 years of hard slog for them and it started with "HF seems down".

Here's what I've (re)discovered:
1. Goldwoods are the best.

2. The more elements there are in array, the smoother the sound.

3. You have to be very particular when soldering the elements.
I have replaced a heap from my spares box (more are on the way) that were non functional. The "new" elements tested perfectly, but after soldering, there is distortion in a couple. This tells me the elements are susceptible to producing distortion if you spend too long on the tabs with the soldering iron. Sometimes, that distortion displays itself as a very shrill sound.
From now on, I will use a couple of artery clips (as heat sinks) each side nearest the element on the tab when reattaching wires.
I use a 3K test tone only.
I ended up replacing 18 of the 40 elements that make up the 2 melded arrays.
I think they're better now than originally built...
Built:
DR 250: x 2 melded array, 2x CD horn, March 2012 plans.
T39's: 4 x 20" KL3010LF , 2 x 28" 3012LF.
WH8: x 6 with melded array wired series/parallel.
Bunter's Audio and Lighting "like"s would be most appreciated...

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