#1
I have a 100w hybrid ss/tube amp and a 4x8 cabinet I picked up cheap about a year ago. Everything was working great until it just did not one day. The amp turns on but I am getting no output from either it or the cab, not even static or scratch or anything. Any ideas or input what may be wrong? I do not think the speakers blew (should still make noise even if they are blown) or I did not have a power hit or anything either.

Thanks.
#2
Quote by klejst
I have a 100w hybrid ss/tube amp and a 4x8 cabinet I picked up cheap about a year ago. Everything was working great until it just did not one day. The amp turns on but I am getting no output from either it or the cab, not even static or scratch or anything. Any ideas or input what may be wrong? I do not think the speakers blew (should still make noise even if they are blown) or I did not have a power hit or anything either.

Thanks.


"I have a car that doesn't go, what's wrong with it?"




I'm thinking we need a bit more information.
“Ignorance more frequently begets confidence than does knowledge.”
Charles Darwin
#3
Quote by klejst
I have a 100w hybrid ss/tube amp and a 4x8 cabinet I picked up cheap about a year ago. Everything was working great until it just did not one day. The amp turns on but I am getting no output from either it or the cab, not even static or scratch or anything. Any ideas or input what may be wrong? I do not think the speakers blew (should still make noise even if they are blown) or I did not have a power hit or anything either.

Thanks.



1. What amp ?

2. What's the cab impedance and are they matched properly to the amp?

3. How long has the preamp tube been in there?
#4
Quote by klejst
Yes of course, my initial post was pretty bland and generic. It is brand "Guitar Research" it was a mini stack they sold as a promo at Sam Ash Music Stores years ago. It is 4 ohms and were built to work with each other. I am not sure about the tube. Should I not still be at least hearing something from the amp and cab? I even tried plugging in a cable to the cab and using a 9v battery to try to get something and nothing.


If you don't even get a click, it may be something as simple as loose or broken wiring inside the cab.
“Ignorance more frequently begets confidence than does knowledge.”
Charles Darwin
#5
I'd start with the tube and fuses. You'll have to poke around a bit.
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#6
It could be the tube but I'm a bit concerned that a 9V battery wouldn't move the speakers. I'd suspect the wiring between the battery and the speakers. Chances are quite low that you've popped all the voice coils, more likely it's a connection inside the cab or the speaker cable and its connections.
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#7
i agree with cath, i wouldn't be surprised if one wire came off of a speaker terminal.

open up the cab and make sure you aren't missing any connections.
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Quote by trashedlostfdup
nope i am "GOD of the guitar forum" i think that fits me better.


Quote by andersondb7
youre just being a jerk man.



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#8
Quote by trashedlostfdup
i agree with cath, i wouldn't be surprised if one wire came off of a speaker terminal.

open up the cab and make sure you aren't missing any connections.


This is the 3rd time he's been told that. I doubt it's getting through.
“Ignorance more frequently begets confidence than does knowledge.”
Charles Darwin
#9
Quote by klejst
What is with some people being so brash on these sites? I was merely telling what I found when I looked in the cab and the amp, all terminal connections seem to be wired up. And looking for more helpful opinions and advice...


The "brash" part is because you're not listening and acting on the very good advice you're getting. You can't *see* a bad connection sometimes. You need to find it.

1. Plug the speaker cabinet into some other amplifier and see if you get sound. If you don't, your problem is the speaker cabinet, so stop looking at the tube and get to work on the speaker cabinet.

2. If the speaker cabinet works just fine plugged into some other amplifier, your problem is the amplifier.

If the problem is the amplifier, you can try replacing the fuses (some fuses may not be in sockets at all, but may be hidden in the amp's internals). You know that it's not the fuse that protects the power if the amp is powering up. You can try replacing the tubes if you like, but you may want to simply take the amp head to a tech and having him diagnose the issue.

If the problem is the speaker cabinet, you should be able to narrow it down, but I'd check the connections to the input jack first, especially if none of the speakers is working. If they're wired in series, of course, then any one of the speakers could take out the entire circuit, but chances are good that it's wired in series/parallel, so at least one bank of speakers should be working. You should educate yourself on how to spot whether a set of speakers is wired in series or parallel. It's all over the net, and is basic information every guitar player should have.

You're also going to need to learn to use a continuity checker. Again, these are dirt cheap and the information on usage is all over the net.

Start there and THEN get back to us with the results.
Last edited by dspellman at Sep 20, 2015,
#10
Unfortunately I do not have another cab to test the amp or an amp to test the cab, I think perhaps it may be the cab though. Upon opening it and looking it over further there is a wire from the input to a contact on one of the speakers and then from there all the other speakers are in series, however there is only one wire from the input where the cable plugs into from the amp, I'm thinking there should be two as there is an empty contact where no wire is attached on one of the speakers. There looks to have been a wire though as half of one is still connected to the input but looks to of snapped off. Strange thing is I don't think it ever was attached when I first got the cab and it worked. Any thoughts? I am very much a beginner to this so I'd appreciate the understanding and lack of knowledge as I have never really tinkered with the insides of an amp or cab but I am learning. Thanks!
#11
Quote by klejst
Unfortunately I do not have another cab to test the amp or an amp to test the cab, I think perhaps it may be the cab though. Upon opening it and looking it over further there is a wire from the input to a contact on one of the speakers and then from there all the other speakers are in series, however there is only one wire from the input where the cable plugs into from the amp, I'm thinking there should be two as there is an empty contact where no wire is attached on one of the speakers. There looks to have been a wire though as half of one is still connected to the input but looks to of snapped off. Strange thing is I don't think it ever was attached when I first got the cab and it worked. Any thoughts? I am very much a beginner to this so I'd appreciate the understanding and lack of knowledge as I have never really tinkered with the insides of an amp or cab but I am learning. Thanks!


Upload some good pictures to photobucket or similar so we can see what you're seeing.
“Ignorance more frequently begets confidence than does knowledge.”
Charles Darwin
#12
Quote by Arby911
Upload some good pictures to photobucket or similar so we can see what you're seeing.


Sure, as you can see below in the first picture, and excuse the semi-good quality iPhone pics, that there is a black wire and white wire from the input jack. It was twisted around the black wire but is broken off midway down before it ever does get to the speaker. If you notice on the speaker with no sticker on it (silver back) there is a contact with no wire connected to it. The last photo shows all the connections. I am not sure if a new wire needs to be ran to that open contact on the speaker from the input where perhaps the white wire did go at one time, funny thing is though when I first opened up the cab the white input wire was never attached and it worked fine before. Hopefully this helps. Thanks everyone.



#13
Reattach the white wire to that terminal. Wires do rattle off at times.
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Randall RM100 & RM20
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Marshall JCM900 4102 (modded)
Marshall 18W clone
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Marshall 1960A
Boss GT-100


Cathbard Amplification
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#14
I finally got around to it, been busy with other things but I reattached a wire from the input jack to the terminal on the speaker as suggested...still nothing. At this point I am not sure if it is the cab or the amp. I cannot seem to find any manual on the amp to help find the fuses, there should still be something even if the tube is "bad" right? I am not getting so much as static, feedback a screech or peep from any of it.
#15
Measure the resistance of each speaker, it should read a couple of ohms lower than the impedance of the speaker.
Gilchrist custom
Yamaha SBG500
Telecasters
Randall RM100 & RM20
Marshall JTM45 clone
Marshall JCM900 4102 (modded)
Marshall 18W clone
Fender 5F1 Champ clone
Atomic Amplifire
Marshall 1960A
Boss GT-100


Cathbard Amplification
My band