Homemade Cab Problem

  • Thread starter Thread starter ZoSo58LP
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ZoSo58LP

ZoSo58LP

rock guy
Hey guys, so recently I've been playing in my band a lot, so every night I play I bring my Gallien Krueger Backline 600 head along with all my stuff (not the cab) to my friends house..there I play through his 4x10 fender cab. At home, I've got my 4x15 Sunn cab that's such a bitch to carry around that I just leave it downstairs. So, being lazy as I am, I always keep my head/all pedals and cables upstairs in my room now and I always wanted a small cab for upstairs playing so I don't have to blast it.....

so here comes my idea: my Crate BFX50 combo amp crapped out a while back. The input just doesn't work, it'll crackle and cut in and out, and it's all on a printed circuit board so I have no idea what I'm doing with that, and frankly I have no want/need to fix it...So I thought, what if I took the Amp part out, took the speaker and used that as a little cab for upstairs playing? It's a 12 incher so it's not bad. So here's what I did (and my problem, it's probably because I did this wrong)

went to radio shack and bought a 1/4 inch panel mount phone jack, which i had then planned to hook the red/black wires from the speaker to. then, i would connect the head to this as a little cabinet.

now, the problem is, it turns on...if i play a note, i hear it for a split second, then the head goes into "protect" mode (the power light turns from green to red, and won't send output anymore until it goes back to green)...so i'm wondering, do the ohms and whatnot not match up possibly? i have no idea what the speaker can handle, as the combo amp was only a 50 watter, and my backline head is a 300 watter.

the back of the head says:

"speaker loads, 4 ohm minimum load total,, 300w) and there's two jacks.

so any ideas? i hope i didn't blow my amp up or anything, but i'm going to stop fidgeting around until someone replies, so that i definitely DON'T blow my amp haha

i also tried grounding the jack to the head itself (since it's metal) with alligator clips and nothing..

here's some pics:

http://picasaweb.google.com/lh/photo/uoa4i9OwfR_4o8OtMZ3gkA?feat=directlink --jack

http://picasaweb.google.com/lh/photo/pH-Oj_sl_M6GXIycG4xS7g?feat=directlink --back of head

http://picasaweb.google.com/lh/photo/ifaO-NDxFxFapSyIH7iWmQ?feat=directlink --whole thing


*oh and yes i did try switching the black/red cables between the two posts*
 
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Arcaxis may be right.

Although I have (unintentionally) used an instrument cable for a speaker cable, it wasn't with a high-powered bass head.

Try a speaker cable.

BTW, If you have only one speaker, it doesn't matter how you wire the speaker to the jack. Also, your speaker is not going to be less than 4 ohms (I've never heard of a single guitar driver with a nominal impedance less than that). So I don't think impedance is your problem.
 
ZoSo58LP said:
Crate BFX50 combo amp ... a printed circuit board so I have no idea what I'm doing with that, and frankly I have no want/need to fix it...
Click to expand...

Would you be interested in parting with the circuit board?? I'll pay shipping. If I can fix it, I'll build a cab, buy a speaker and have a little practice amp.

peace,
 
hey guys, thanks for the idea. i was using a regular guitar cable *DUH*...i'll try the one that i always used with this head...duh me, rgiht? haha

hey chili, where are you located? if i get this working, i won't have any need for the actual amp part of this thing. PM me and lemmie know!
 
hmm i just tried using my cable to hook my head to my cab with no avail. she's still going into protect mode. any thoughts?
 
good thinking. i figured it was the amp on the crate because it all has to do with the input jack: if i wrapped it around the amp in a certain way, it would stay on...once it became loose, then it would cut out. i'm pretty sure it's the input jack on the BFX 50 amp itself.

i just tried it by using the headphone jack....the input jack is still messed up, but less so now because the vibrations from the speaker cabinet aren't screwing it up nearly as much...so you can play without it cutting out, but if you move the wrong way and hit the cord at the input, it crackles and goes out.

as for the gallien krueger, if i play very lightly, it won't go into protection mode....but the second i strike it harder it goes into it. here's what the manual says about protection mode:

"Smart Protection Circuitry:
The Backline Series protection circuitry constantly
monitors for unsafe operating conditions such as short
circuits, miswired speaker cables, blown speakers, improper
ventilation and incorrect speaker configurations.
In addition, protection is provided during power up/power
down. If the Backline unit senses any unsafe operating
conditions, the output signal is immediately muted and
the power light changes from Green to Red. The amplifier
will remain muted until the fault is removed. If the
protection circuit activates while playing, turn the
amplifier off and check the amplifier speaker output
connections. Be sure that you are not exceeding the
maximum recommend load described in this manual. If
the problem persists, contact GK directly for technical
advice."

it says that when the problems removed, that's when it'll go back to green...but mine goes to green if i just stop playing and let it sit for a second. odd?
 
arcaxis said:
Are you 100% sure it's the amp part of the Crate that crapped or could it possibly be the speaker itself that's opening intermittently when you push something into it? Voice coil wire loose off the speaker cone?

"it'll crackle and cut in and out"

"if i play a note, i hear it for a split second"

Can you connect/hotwire the Crate amp guts to your other cab to see if that combination works? This might give a hint which part is hosed.
Click to expand...

Hey man, don't mess up my score on a bass amp!! :mad: :D

But seriously, this is good advice and you should be sure what part is actually bad. If you find the amp board is indeed bad, I'd like to take it off your hands and see if I can fix it. I'll send you a PM.

If it isn't the amp board, then you've still got a good practice amp with a new speaker. Easy enough to change one of those out.

I found the manual online and see the stock speaker of the Crate is 8 ohm. I don't think that would make a difference, but it might. You aren't cranking the GK amp at all, are you? 300w into a 50w speaker would definitely trip a protection circuit if it's turned up. Start with the volume all the way down.
 
hey chili, yeah i just saw that it was 8 ohm too...hmm ill be honest i dont know much about OHMS...but the back of the GK says "4 ohm total minimum" and there's two quarter inch outs on there.

i've also got the voilume very low...and i have the -10db padding switch in, so it's even lower. i did notice, however, like i said the harder i play the quicker it shuts out....when the -10db switch is out and it's louder, it cuts out even quicker. volume seems to be something wtih this, but i have no idea what



hmm *EDIT*.....i just got it to play a bit by switching the output from the left one in the back of the GK to the rgiht one..played a bit..lower levels...then it got reawlly loud and the protection mode went on....now the cab smells odd. hahaha did i just expode my speaker, despite the fact it was at a low volume?
 
Yeah, it should be fine with an 8 ohm speaker. The 4 ohm is a minimum, which means you don't want to go lower than that, but going higher would only lower the power rating to the speaker; something like that. It should work at 8 ohms.

It's quite possible the speaker just can't be used with the GK head. You most likely need a higher rated speaker.

Edit: I just read your edit. Smelly stuff means somethign fried. Probably the voice coil of the speaker. Ooops. For sure that speaker was too small for that amp.
 
yeah i see smoke coming out of the port holes. i just took it apart. how in the hell could i have fried this so much? it was such little output from the head..

also just did the 9 volt battery test, and the speakers moving/making the noise. maybe it didn't fry? what the hells going on here...hhahah
 
cool! i'll check these out.

fyi, i just hooked my zune to it and it's playing it fine....i think the actual wires that are bare that hook to the speaker were causing a problem, as if i move thjose wires i get the crackling.



*edit*

well i got it working, hmm..... basically i came to the conclusion that the lil wire board that's attached to the main bare wires from the speaker wasn't connected to the speaker. it was just floating there, and it looks like it was once riveted on, but the rivet broke...therefore, when these two wires touched it would crackle and go out..aka, why the GK kept going into protection mode. i taped it up with hockey tape and played, even played loud, and it didn't once go into protection mode and it sounded perfect.

so tomorrows project, i guess, is to figure out how to drill out that broken rivet, and hopefully get a screw that fits that hole and screw that piece back in place, then electrical tape it just as a backup. here's some pics

http://picasaweb.google.com/lh/photo/dsy4vZ7PWr5I75hICM48Xw?feat=directlink -- friggin messy room while doing all of this tonight!

http://picasaweb.google.com/lh/photo/nFuf8DXwAn5DXz9_pz_2Ww?feat=directlink --broken rivet and piece
 
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The second pic tells it all. The bare wires were touching the speaker frame and causing a direct short; probably when the speaker starts moving.

Cool you found it.
 
Chili said:
The second pic tells it all. The bare wires were touching the speaker frame and causing a direct short; probably when the speaker starts moving.

Cool you found it.
Click to expand...
It looks to me like the two flexible wires (tensor wires?) that run from the card to the voice coil were touching each other when the speaker cone moved. They are not (cannot be) insulated. Either single wire touching the speaker frame wouldn't cause a problem because the speaker frame is electrically floating. It's painted, anyway.
 
arcaxis said:
ZoSo58LP.......
Rather than attempting to drill out the rivet and risk punching through and damaging the speaker cone, you might be able file off what's left of the rivet and gently tap it out with a Philips screwdriver that has a tip larger than the hole.
Click to expand...
Push the card back onto the rivet. Put a dab of JB Weld on the head of the rivet and on the card surrounding it. Place the speaker in such a way that the card is flat so that the stuff doesn't run, and let it set. If you use JB Quick (quick setting JB Weld), you can be playing again in an hour or less.
 
ggunn said:
Push the card back onto the rivet. Put a dab of JB Weld on the head of the rivet and on the card surrounding it. Place the speaker in such a way that the card is flat so that the stuff doesn't run, and let it set. If you use JB Quick (quick setting JB Weld), you can be playing again in an hour or less.
Click to expand...
That's what I would do.
Actually, on similar problems in the past I just used duct tape but the JB Werld would be better.

And the leads to the voice coil could be insulated. There's no reason electronically that they couldn't and I have, in fact, seen a couple of oddball speakers that had them insulated.
But those leads need to be flexible and insulation reduces the flexibility so that's why they don't typically insulate those wires.
 
Lt. Bob said:
And the leads to the voice coil could be insulated. There's no reason electronically that they couldn't and I have, in fact, seen a couple of oddball speakers that had them insulated.
But those leads need to be flexible and insulation reduces the flexibility so that's why they don't typically insulate those wires.
Click to expand...
I've never seen that, but I guess it's possible. All I've ever seen have been loosely braided uninsulated wires. For the flexibility, yes, not for any electrical reason.
 
hey guys! update!

thanks for all the replies..it's awesome coming here when i've got a problem, and brainstorming with everyone else in order to get a solution...love it!

so the whole, broken rivet, bare wires touching eachother was the problem. thank god the smoke and burning i smelled last night WASN'T the speaker frying. i actually ended up just re-drilling, very carefully, the whole and putting a set screw in there. (should've came online today to read your suggestions before i did this, UGH! haha glad i didn't ruin the speaker though!)

then, i soldered up my input end. i had the genious idea to drill a hole in the top hollow part of the cab so that i could mount the input like it would be on a real cab! well, i did. then i realized that on the input connector, the jack wasn't nearly long enough...haha so there was like an inch of wood before you actually hit the input....basically, the width of the wood used on the top of this cab was a few inches more than the up/down length of the input...DOH!

oh well, there's a hollow opening were the amp used to be, so i think i'm going to rig up a thin piece of wood or something and hook the input to that, you'll see what i mean in the pics...other than that, she sounds pretty cool! very nice for a little practice cab. attached are some pics, and i made a few videos of me just futsin around today

http://picasaweb.google.com/lh/photo/AQCZYZfM971MWwBhCy1rog?feat=directlink

http://picasaweb.google.com/lh/photo/sVwywQnf_DU-l6mfw3jO7Q?feat=directlink

http://picasaweb.google.com/lh/photo/DA0le4atybnPYsJxOOVNUA?feat=directlink


https://www.youtube.com/watch?v=BAyRn0AcCok

https://www.youtube.com/watch?v=Y9J_M-o7wPE - my first venture into headstock cam haha, it's so hard

https://www.youtube.com/watch?v=kFMS6-Dj0o4
 
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