Amp suddenly sounds muddy

[Blaoskaak]

Hi,

A few minuts ago i was playing guitar and suddenly volume dropped a bit and everything sounds muddy and sounds not bright.

I did some research and find out that it can be a tube.

My amp is sv20h, i play with a attenuator ( harley benton pa-100 )who can handle 100w amps.

Volume on attenuator was on 0,5 at the moment. And high treble on amp is on 7 and i have channel 1 and 2 linked.

Can the attenuator in 0.5 be the problem?

If i need to replace my tubes, what tubes shall i buy? Is there any diffrence with vintage and modern?

Thanks!

 

[Troy T. Blues]

Have you tried it without the attenuator?

It could be a bad preamp tube. Do you have any extra ones? If not, take one from another amp, and swap each one individually, right down the line, by process of elimination. That's where I would start.

Tung-Sol, EH, Mullard Ri's....all good for a Marshall for current production.

 

[Blaoskaak]

Have you tried it without the attenuator?

It could be a bad preamp tube. Do you have any extra ones? If not, take one from another amp, and swap each one individually, right down the line, by process of elimination. That's where I would start.

Tung-Sol, EH, Mullard Ri's....all good for a Marshall for current production.

Yup, i tried it without attenuator. I don't have another amp. So i guess i just buy some tubes and try it out. If it is not the problem, i have some spare ones.

 

[Troy T. Blues]

Yup, i tried it without attenuator. I don't have another amp. So i guess i just buy some tubes and try it out. If it is not the problem, i have some spare ones.

Cool. Yeah, that's where I would start. Check all your cables too

 

[Blaoskaak]

Ok. Great! Thanks

 

[Blaoskaak]

Cool. Yeah, that's where I would start. Check all your cables too

How do i know what nu pre tubes are?
My amp has the following tubes: 2x ECC83, 1x ECC83 (phase splitter), 2x EL34

I found these tubes on thomann: https://m.thomann.de/nl/tungsol_nn0...JpJPsKrW0h9O1TV5Tt6eRuDXMl-YLS0caAmaWEALw_wcB

Are these pre tubes?

 

[Troy T. Blues]

ECC83 is the same as 12AX7 (those are the preamp tubes) EL34's are the power tubes.

Sorry, that link doesn't work for me.

 

[Neptical]

Are these pre tubes

Yep! 12AX7 is what you're looking for. EHX are also fantastic tubes for the price. Make sure those filaments on the power tubes look okay as well.

 

[Chris-in-LA]

Yup, i tried it without attenuator. I don't have another amp. So i guess i just buy some tubes and try it out. If it is not the problem, i have some spare ones.

And, without the attenuator, how did it sound? I’ve had attenuators go “bad” over time and I could not get a good tone until I unplugged the attenuator.

 

[Blaoskaak]

ECC83 is the same as 12AX7 (those are the preamp tubes) EL34's are the power tubes.

Sorry, that link doesn't work for me.

Ok. The link are tuning Sol nn099-g tube 12ax7. They are a bit more expansive then other ones. Do you hear a diffrence in diffrent pre amps?

Yep! 12AX7 is what you're looking for. EHX are also fantastic tubes for the price. Make sure those filaments on the power tubes look okay as well.

Thanks! Will look at it too.

And, without the attenuator, how did it sound? I’ve had attenuators go “bad” over time and I could not get a good tone until I unplugged the attenuator.

I tried it without de attenuator. Didn't help. A attenuator should be able to play on 0.5 volume or not?

 

[Chris-in-LA]

Ok. The link are tuning Sol nn099-g tube 12ax7. They are a bit more expansive then other ones. Do you hear a diffrence in diffrent pre amps?



Thanks! Will look at it too.



I tried it without de attenuator. Didn't help. A attenuator should be able to play on 0.5 volume or not?

The attenuator is probably ok, then.

 

[Iron1]

Definitely seems like you dropped a tube to me from what you're describing. There's a few places out there that sell "tube kits" based on what amp you have, if one dropped might not be a bad idea to get a whole set and replace 'em all, then keep the old ones that aren't dead as spares.

 

[Blaoskaak]

Definitely seems like you dropped a tube to me from what you're describing. There's a few places out there that sell "tube kits" based on what amp you have, if one dropped might not be a bad idea to get a whole set and replace 'em all, then keep the old ones that aren't dead as spares.

With dropped you don't mean fall on the ground do you?

Replace only the pre amp or with the power tubes too?

 

[Iron1]

With dropped you don't mean fall on the ground do you?

Replace only the pre amp or with the power tubes too?

By dropped I mean it burned out/stopped working. And, yeah, I’d replace em all. If ones died the others might not be far behind.

 

[Blaoskaak]

By dropped I mean it burned out/stopped working. And, yeah, I’d replace em all. If ones died the others might not be far behind.

Oké great! Will do that. Gonna buy the tubes today. Hope that the problem is solved then.

 

[Iron1]

Oké great! Will do that. Gonna buy the tubes today. Hope that the problem is solved then.

While I can't promise you - sight unseen - that this will fix it, it sure sounds like it should. And, as if on cue, I just read this in a manual for a new (to me) amp I just bought:

 

[dro]

It is also possible (not likely) but possible for a tube to burn out in a month. Tube amps do need a bit of maintenance. So keeping a set of new tubes, both pre and power. Is a good idea. Back in the old days. You could buy tubes anywhere. So not such a big deal. But today, on line is pretty much the only outlet. A good idea is, do a little research. Buy a few different brands. Different tubes can also make youre amp sound different. Even different tubes of the same brand. Make sure power tubes are matched. You may never need them. But if you do. It's nice to get them off the shelf, and not be without sound.

 

[Blaoskaak]

I built and sold OC44 rangemaster clones for a while. If you can get your hands on a rangemaster circuit, get it. I've tried lots of treble boosters and the rangemaster sounds good with just about all amps.

While I can't promise you - sight unseen - that this will fix it, it sure sounds like it should. And, as if on cue, I just read this in a manual for a new (to me) amp I just bought:

It is also possible (not likely) but possible for a tube to burn out in a month. Tube amps do need a bit of maintenance. So keeping a set of new tubes, both pre and power. Is a good idea. Back in the old days. You could buy tubes anywhere. So not such a big deal. But today, on line is pretty much the only outlet. A good idea is, do a little research. Buy a few different brands. Different tubes can also make youre amp sound different. Even different tubes of the same brand. Make sure power tubes are matched. You may never need them. But if you do. It's nice to get them off the shelf, and not be without sound.

Ok , I took my amp to the music store. Told them I needed new tubes. The gentleman said: come along with the amplifier and then I can see which tubes are in it and then you get the good ones.
When I arrived the technical service connected the amplifier to the radio???? this sounded good and then he indicated that the amplifier is good and new tubes are not needed. Also both pre-tubes are glowing and this also said that everything was good.

He said it was one of the cables. He told me to measure it. Now I have come home and I think all cables are good. Put the multimeter on 200v and there is about 70v going through the cables.
I recorded an audio fragment so you can hear how the amplifier sounds.

https://voca.ro/kBZAbeS6eIm

 

[Troy T. Blues]

Ok , I took my amp to the music store. Told them I needed new tubes. The gentleman said: come along with the amplifier and then I can see which tubes are in it and then you get the good ones.
When I arrived the technical service connected the amplifier to the radio???? this sounded good and then he indicated that the amplifier is good and new tubes are not needed. Also both pre-tubes are glowing and this also said that everything was good.

He said it was one of the cables. He told me to measure it. Now I have come home and I think all cables are good. Put the multimeter on 200v and there is about 70v going through the cables.
I recorded an audio fragment so you can hear how the amplifier sounds.

https://voca.ro/kBZAbeS6eIm

OK. Well I did mention early in the thread to check your cables too

 

[Kelia]

Ok , I took my amp to the music store. Told them I needed new tubes. The gentleman said: come along with the amplifier and then I can see which tubes are in it and then you get the good ones.
When I arrived the technical service connected the amplifier to the radio???? this sounded good and then he indicated that the amplifier is good and new tubes are not needed. Also both pre-tubes are glowing and this also said that everything was good.

He said it was one of the cables. He told me to measure it. Now I have come home and I think all cables are good. Put the multimeter on 200v and there is about 70v going through the cables.
I recorded an audio fragment so you can hear how the amplifier sounds.

https://voca.ro/kBZAbeS6eIm

Nice overtones !