Valve amp problems: powers up but no sound

[Mind_Riot89]

This is the first time I've ever had an actual problem with a valve amp so here goes. I was playing my Laney LC30 at band practice and noticed my tone was brittle and trebley and after about 10 minutes there was no sound coming from the amp at all. No hiss, no hum, nothing. The amp still powers on fine, the fuses are all good and all the valves light up and look normal; how do I tell whether they're dead? Oh, and I tested the speaker with another amp, no problems there. God, I feel like such a noob again.

 

Any idea what's wrong? Oh, and anyone know of any amp techs/repairs in Gloucestershire/Oxfordshire/Cardiff? Thanks!

[Freq67]

 

This is the first time I've ever had an actual problem with a valve amp so here goes. I was playing my Laney LC30 at band practice and noticed my tone was brittle and trebley and after about 10 minutes there was no sound coming from the amp at all. No hiss, no hum, nothing. The amp still powers on fine, the fuses are all good and all the valves light up and look normal; how do I tell whether they're dead? Oh, and I tested the speaker with another amp, no problems there. God, I feel like such a noob again. Any idea what's wrong? Oh, and anyone know of any amp techs/repairs in Gloucestershire/Oxfordshire/Cardiff? Thanks!

 

 

 

Does it have 4 output tubes or 2?

[theboywho]

It does sound like it could be valves, any way of testing current valves or trying others out in the amp?

I know a decent tech, I'll dig up the number and PM you later.

[daysofspeed]

I think your power valves maybe going out and have prob taken out your ht fuse. Change the fuse and see if it goes again if so change your power amp valves.

 

I've recently had this problem with my ac15. Make sure you get the right fuse when you replace it. Either fast or slow blow.

[Mind_Riot89]

 

It does sound like it could be valves, any way of testing current valves or trying others out in the amp? I know a decent tech, I'll dig up the number and PM you later.

 

 

Brilliant, thanks bud. The fuses both look fine which is what makes me suspicious; maybe I'll try fitting a new one. It's got 4 power and 4 preamp valves.

[t_e_l_e]

no sound at all, sounds in the first place one of the preamp tubes is dead

if power tubes (especially el84) are dead, they make some crackle sound and noise, and if only one of the powertubes are dead (most of the time only one goes) the others would still produce some output not nice sound tough, but if a preamp is dead most amps signal is dead aswell

 

get one working spare preamp tube

replace the known working with the first tube, turn on and check

if amp works, problem tube found happy playing

if not, put the first removed tube in the place of the second preamp tube, turn on check if it works gottcha happy playing, if not continue this step until you check all 4 preamp tubes

 

95% you find the one and only broken preamp tube with this method, its unlikely that more than one is broken, then you would need more spare tubes

 

if you have power tube problems, you can use the same method, but its a bit clumsy, cause power tubes become very hot, so you need to wait some minutes until you can touch them with the fingers and replace them

 

the lc30 is an autobias el84 amp, so matching powertubes is not really a must have, nice to have but no must.

if its not a preamp tube, you can also replace all 4 powertubes with a set of 4 new ones...

 

for el84 amps it is also good the have a working set of el84 tubes spare and at least one working preamp tube.

these are the most common problems and easy to fix.

 

if changing tubes does not solve your problem bring the amp to a tech

[BigStu81]

Hey guys,

 

I had to bump this thread as I don't think I have a high enough post count to create new topics.

 

I'm totally stumped right now. I recently bought an Idiopan steel tongue drum which has a pretty rudimentary pair of pickups in it which can be played through a bass/guitar/keyboard amp - connects via 1/4 jack just like a guitar.

 

I then bought a small cheapo bass amp (Laney LX10b) the other day to play it through but am not getting any sound through the amp.

 

Points to consider:

 

- I tested the AUX IN on the amp with an mp3 player to ensure that the speaker works (it did)

- I also tested the Jack input on amp with the same mp3 player (using a an adaptor)

- The guitar lead could be the issue but I doubt it as it's brand new and makes a noise when I touch the end - i.e. it isn't dead.

- The drum was demoed to me via video the day before it was despatched from the US to my home in the UK - so was working two days prior to my receipt. The box also didn't look like it had been bashed/dropped. It could be that vibrations have shaken loose a connection but when I look in the hole in the top it all looks fine.

- Really strange is that I can hear noise through the amp if I tap the pickups or touch the wires, but they are not picking up the the frequencies of the drum - I presume this means that the jack is working as it's transmitting sound from the pickups.

- There is no volume/tone controls. Just pickups inside the drum going to a jack.

 

Any advice would be really appreciated. Shipping was $80 one way so I don't want to send it back to the US and pay $160 plus repair fees unless I really have to.

 

Cheers

 

​Stu

 

[WRGKMC]

The thing your assumed as being good, "the cord" is the most likely suspect by your description. Cheap cords only take one tug and you can have the wires short together inside the plug casing. Unscrew the caps and take a close look and make sure the ground wires are not touching the hot wires. With only a single thread of wire touching you may still get a small amount of signal through the wire.

 

You can plug the cord in by itself, turn the amp down low, then touch the tip. You should get a loud hum in the amp is the chrd is good. If not try another.

 

If you get hum yet no signal plugged into the guitar, the problem is likely in your guitar wiring. If theres no hum, yet you hear the hiss of the power amp in your speakers having a cracked solder joint or bad input jack is the first place to look. Again a good tug on a cord can crack the solder joints of a PC mount input jack. The plastic jacks are the worst because they can fail just for heat. Make sure the nuts that hold them in place are tight buy not overly tight.

[BigStu81]

Thanks a lot for the reply, man.

 

It's not a particularly cheap lead. It's a brand new Fender tweed one, and it's never been tugged on or had a cab wheeled over it etc. I also get the characteristic buzz when I touch the end of the lead so I think it's working.

 

However, the Idiopan was also working in the video I was sent two days before I received it in the post. I also shone a light inside it and the soldering looks to be intact.

 

It's odd that it picks up the sound of me tapping the pickup but doesn't pick up the sound of me playing.

 

[t_e_l_e]

can post a link to the video, cause i absolutely have no clue how this "drum" looks like... maybe then i or any other might get an idea what you could check

[BigStu81]

Here you go. As you can see, it's a pretty simple setup...

[SmoggyTwinkles]

Could it be that those pickups are piezo and maybe require a pre-amp to essentially boost the sound?

 

Do you have a pedal like an overdrive or something you could put between and see if it's just too low a signal for your guitar amp?

 

I have no experience with piezo pickups just trying to come up with ideas, lol.

 

Have you tried googling your tongue drum, or perhaps posting this problem on a forum more specific to that instrument?

[Phil O'Keefe]

Hey guys,

 

I had to bump this thread as I don't think I have a high enough post count to create new topics.

 

I'm totally stumped right now. I recently bought an Idiopan steel tongue drum which has a pretty rudimentary pair of pickups in it which can be played through a bass/guitar/keyboard amp - connects via 1/4 jack just like a guitar.

 

I then bought a small cheapo bass amp (Laney LX10b) the other day to play it through but am not getting any sound through the amp.

 

Points to consider:

 

- I tested the AUX IN on the amp with an mp3 player to ensure that the speaker works (it did)

- I also tested the Jack input on amp with the same mp3 player (using a an adaptor)

- The guitar lead could be the issue but I doubt it as it's brand new and makes a noise when I touch the end - i.e. it isn't dead.

- The drum was demoed to me via video the day before it was despatched from the US to my home in the UK - so was working two days prior to my receipt. The box also didn't look like it had been bashed/dropped. It could be that vibrations have shaken loose a connection but when I look in the hole in the top it all looks fine.

- Really strange is that I can hear noise through the amp if I tap the pickups or touch the wires, but they are not picking up the the frequencies of the drum - I presume this means that the jack is working as it's transmitting sound from the pickups.

- There is no volume/tone controls. Just pickups inside the drum going to a jack.

 

Any advice would be really appreciated. Shipping was $80 one way so I don't want to send it back to the US and pay $160 plus repair fees unless I really have to.

 

Cheers

 

​Stu

 

 

 

 

 

Starting at one end and substituting out the various elements of the signal chain with "known working" components until you find the problem component is a generally accepted way of troubleshooting. The alternate approach is to simplify the chain to the bone, then add things back to it one at a time until you find the culprit, but that approach is less relevant in your situation; the chain is already about as simple as possible.

 

You've confirmed the amp isn't the problem via the MP3 player and adapter feeding the main input test.

 

You've confirmed that the cord isn't shorted with the "touching the end" test, but I'd suggest using a different source instrument to double-check that - if you have a guitar, bass or keyboard (or can briefly borrow one) try using the cable to plug it into the amp and check - if it works, the cable and amp are "known good", and not the source of the problem. I still am not convinced that the cable isn't the problem, and would recommend trying a different one if you have one available.

 

That leaves the pickups and jack on the instrument itself. It's possible one of the two connections on the output jack inside (visible in your pictures) is bad. That's super-easy to touch up if you know how to solder. Outside of that, I don't know what else to check... it's doubtful that both pickups (there appears to be two - I suspect they're some sort of piezo contact pickups) would be bad at the same time - especially if everything was working just a few days ago before it was shipped across the pond to you.

 

Have you tried contacting the seller / manufacturer to see if they have any suggestions? Were they plugging the drum straight into a regular guitar / bass amp, or were they using a preamp / impedance adapter of some sort? Piezo pickups are usually very high impedance, low output devices. I'd expect to hear something when one was plugged straight into an amp, but maybe it's not a piezo based system.

[WRGKMC]

Hum touching the tip of the cord tells you the hot leg of the lead is likely working. However it doesn't tell you is the ground is good. Just try a different cord first. The simplest items, that are most accessible to the user of the gear are usually responsible for 90% or the failures. Start with all exterior items that are in the signal path before you work inward to things you have no access to.