I have a small bird chirping or a cricket in my Jack cab.

The Jack of All Trades pro-sound cabs.
Post Reply
Message
Author
CEF
Posts: 31
Joined: Mon Feb 08, 2016 7:27 am
Location: UK

I have a small bird chirping or a cricket in my Jack cab.

#1 Post by CEF » Sun Oct 15, 2017 12:51 pm

Hello everyone.
I would like to pick the collective brain for some help please?
My Jack 2x12 with melded array has developed a distorting sound and an annoying bird or cricket like chirp coming out of the melded array. Right up in that sort of 16k range but the 16k on the EQ is virtually off, but it is in that sort of area. I resolved the distorting type sound when I systematically went through all the connections and re-solderd anything I didn't like the look of and removed the Lpad I had installed when I got it made. hoping this would kill two birds with one stone. This chirp is the first issue I have had with the Jack.
As I don't own any of the schematics or build lists for the BFM cabs. What would be the correct value switch for me to use in the melded array to turn it on and off? I presume it is a DPDT of some kind.

It does the chirp at all volumes (above 1) and can be set off by banging your fingers down on the strings, like you would when muting with you neck hand and slightly muting with you picking hand and not really playing any thing of note. Also palm muting the strings and playing with a plectrum makes it do it.
I have had the array out to check its soldering and also to see if it was any particular one of the piezo's is the culprit. It appears to be coming out of all of them or I can't decide which one it is coming from.

Any help, tips or advice on what I should test, fix or otherwise would be great appreciated.
Thank you.

User avatar
Bill Fitzmaurice
Site Admin
Posts: 25843
Joined: Tue May 02, 2006 5:59 pm

Re: I have a small bird chirping or a cricket in my Jack cab.

#2 Post by Bill Fitzmaurice » Sun Oct 15, 2017 1:30 pm

You can't use an LPad with piezos. Its presence indicates the cab probably wasn't built to spec.

CEF
Posts: 31
Joined: Mon Feb 08, 2016 7:27 am
Location: UK

Re: I have a small bird chirping or a cricket in my Jack cab.

#3 Post by CEF » Sun Oct 15, 2017 2:06 pm

Thank you for replying Bill. Would this mean that all the piezo's are damaged. Or could the cross over be in need of attention? I rulled it out when I looked everything over because there was no burning smell, nothing looked burnt out or an open circuit type situation.

User avatar
Bill Fitzmaurice
Site Admin
Posts: 25843
Joined: Tue May 02, 2006 5:59 pm

Re: I have a small bird chirping or a cricket in my Jack cab.

#4 Post by Bill Fitzmaurice » Sun Oct 15, 2017 3:28 pm

Since an LPad was used I can't assume that the crossover was properly done. If it wasn't all sorts of bad things could happen, including amp damage.

CEF
Posts: 31
Joined: Mon Feb 08, 2016 7:27 am
Location: UK

Re: I have a small bird chirping or a cricket in my Jack cab.

#5 Post by CEF » Sun Oct 15, 2017 3:48 pm

How would you recommend I go about checking if things were done correctly per your spec please.

User avatar
DJPhatman
Posts: 5402
Joined: Mon Aug 14, 2006 5:08 am
Location: Warren, MI
Contact:

Re: I have a small bird chirping or a cricket in my Jack cab.

#6 Post by DJPhatman » Sat Oct 21, 2017 11:30 pm

I see you made it in! :hyper:
CEF wrote:How would you recommend I go about checking if things were done correctly per your spec please.
Buy the plans!

Using just the feed wires to the array, generate "white noise" using the headphone out of a computer, or a portable radio not tuned to any station. Using the cardboard core from a full roll of paper toweling, listen to each individual piezo transducer, paying attention to the sound levels. Replace any that make no sound at all or are suspect. Remember, your ears can easily be fooled, and RTA spectrum analyzer cannot. Rent one if you can't afford to purchase. Cheers!
I know money often seals the deal, but seriously, quality is an investment, not an expense... Grant Bunter
Accept the fact that airtight and well-braced are more important than pretty on the inside. Bill Fitzmaurice

User avatar
Bill Fitzmaurice
Site Admin
Posts: 25843
Joined: Tue May 02, 2006 5:59 pm

Re: I have a small bird chirping or a cricket in my Jack cab.

#7 Post by Bill Fitzmaurice » Sun Oct 22, 2017 8:00 am

DJPhatman wrote: Using just the feed wires to the array, generate "white noise"
Use pink noise, not white noise.

CEF
Posts: 31
Joined: Mon Feb 08, 2016 7:27 am
Location: UK

Re: I have a small bird chirping or a cricket in my Jack cab.

#8 Post by CEF » Sun Oct 22, 2017 2:37 pm

Thank you gents. This is very much appreciated help.

CEF
Posts: 31
Joined: Mon Feb 08, 2016 7:27 am
Location: UK

Re: I have a small bird chirping or a cricket in my Jack cab.

#9 Post by CEF » Fri Nov 03, 2017 2:58 am

Just in case you interested in the out come of the pink noise test. More than certain it is the piezo's rather than the crossover. The pink noise seemed inconclusive at first but after starting listening to the array in different places I think there are a few that were under powered in comparison to others that most definitely had the pink noise coming through. Going to take the backs off the housings and see which ones torn.

CEF
Posts: 31
Joined: Mon Feb 08, 2016 7:27 am
Location: UK

Re: I have a small bird chirping or a cricket in my Jack cab.

#10 Post by CEF » Wed Nov 15, 2017 4:01 am

Just an update.
It did turn out IMHO to be the piezo's. Did one last test before taking the backs off the piezo's without the crossover inline and it confirmed that the piezo's were the culprit. I have found a varying degree of unhappy piezo's. Couple sted fastly stuck in place. A large amount of the 14 piezo's that are in place. I have no idea how they stayed in place due to the massive amount of lateral movement and crunchy noise they make when moving them. They are being held inplace but I have no idea by what. So replacing all them is the route I will go with a few in contingency as we can't predict there quality.

CEF
Posts: 31
Joined: Mon Feb 08, 2016 7:27 am
Location: UK

Re: I have a small bird chirping or a cricket in my Jack cab.

#11 Post by CEF » Mon Jan 01, 2018 10:46 am

Just another update. But one from a much happier place.
Replaced all the piezo's and on testing and visual inspection much better product to work with from the get go.
Found some pictures of how others had made their cross overs on here and decided that was going to get a make over as well. Due to the fact I didn't like the look of it had been built in the nice and correct way most of you do it. Thus eliminating what I think was the source of my problems. Watch this space for when I hook it all back up.

CEF
Posts: 31
Joined: Mon Feb 08, 2016 7:27 am
Location: UK

Re: I have a small bird chirping or a cricket in my Jack cab.

#12 Post by CEF » Wed Jan 10, 2018 5:28 pm

Hopefully this will be my final post in this thread. So I would like to say thank you for the help I recived in getting this cab fixed. So after methodically going over the whole cabs wiring & connections, replacing the melded array and Xover. I gave it, its first test flight today at a volume I thought I could get away with at home and it sounds like a new cab with all the problems gone and different from the one originally I got. Just have to play it in anger at a rehearsal to give it, its final thumbs up. Thank you again. Peace.

CEF
Posts: 31
Joined: Mon Feb 08, 2016 7:27 am
Location: UK

Re: I have a small bird chirping or a cricket in my Jack cab.

#13 Post by CEF » Wed Feb 14, 2018 1:44 pm

Last post and all is well in Jack land.
After a really long time waiting to use my cab in anger. I had a rehearsal and it really does sound like a different beast after I refitted. A really great sounding cab now, way better and way more like what I was expecting. Nice earthy Hifi quality, is the best way I can describe it. Great presence in the mix
Thank you for all the help.

Post Reply