Tube amp help needed... PLEASE!!

B

BloodRose

Professional Scapegoat
My Splawn amp is acting up... whenever I hit notes/chords on the low strings, I get a flubby sound kinda like when you make "raspberry" sounds with your mouth.. I thought it was a bad preamp tube. I got a new one and rolled it thru all the positions and used a cleaner on the pins and worked it in and out and then I cleaned the pins on the power tubes too.. it doesn have much play on it and is very clean inside as its always covered. That didnt fix the issue.. I guess Ill try a retube, but anyone have any other ideas first? It has maybe less than 20 hours of play and maybe 2 hours at gigging volume..

thanks
 
Re: Tube amp help needed... PLEASE!!

Lake Placid Blues said:
This sounds like a microphonic POWER tube.
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Yep, thats what my Quick Rod sounded like after i discovered I'd blown a power valve? I revalved with JJs and the problems gone now.

1 thing I will say is that mine was biased very hot for the valves that were in there, had to turn the bias pot all the way down almost to get the right settings for the JJs.
 
Re: Tube amp help needed... PLEASE!!

thanks guys!! I was figuring Id have to retube, but was worried that it was something else and it would tear up the new tubes or something.. (had an amp before that did that)

Ill order a full set of tubes for her.. Itchin to play it again!!
 
Re: Tube amp help needed... PLEASE!!

BloodRose said:
2010. about 15-20 hours of play
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Play time has little to do with the lifetime of some things in tube amps...filter caps for example start wearing out the day they are hit with voltage for the first time and there is no way to stop it.

I've played amps that had almost no play time on them, never been gigged but still needed a cap job because they had just gotten to be that age.

However a 2010 model amp should be years away from anything like that...
 
Re: Tube amp help needed... PLEASE!!

Yep.. barely broken in.. I surely havent played it as much as Id like.. and have rarely run it at gig levels.. Orig owner barely played it
 
Re: Tube amp help needed... PLEASE!!

BloodRose said:
Yep.. barely broken in.. I surely havent played it as much as Id like.. and have rarely run it at gig levels.. Orig owner barely played it
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That's part of what my point is...things like tubes and speakers, those items have a lifetime that can be based on hours of playtime however it does depend on how hard that play time was. On a speaker for example 10 hours at whisper level in a bedroom and 10 hours runnning at full tilt are 2 very different things.

However things like Filter caps start wearing out and breaking down as soon as the amp is turned on for the first time...

If you packed that amp away right now for 10-15 years then broke it out it might fire up fine and run alright but the first time you get in it hard and kick it in it's ass the power filters will likely give it up even if it's only got 15 hours of play time on them.
 
Re: Tube amp help needed... PLEASE!!

What were the stock tubes in your Splawn (if you bought it new)? I had a stock Mullard re-issue EL-34 go pretty quick in my Quickrod. I don't think they use those these days for that reason.......
 
Re: Tube amp help needed... PLEASE!!

I had some similar experience with just one amp. The amp, some day started to sound as if the speaker was farting, ruinning the sound.
I went first swapping pre-amp tubes (except PI) and, surprised, swapped power tubes... to discover late that the tube that was wrong was just the PI.
Swapped the PI and everything started to sound as usual.
For a while, I thought the speaker cone was the issue.
90% of issues are coming from a bad working tube and, current production tubes are less reliable. I had tubes that worked just 3 hours and tubes that are still working fine after 3 years. You never know how long will stand a tube.
 
Re: Tube amp help needed... PLEASE!!

Bro take a pencil and tap lightly on your tubes if one is microphone you should hear it.
 
Re: Tube amp help needed... PLEASE!!

metlking said:
What were the stock tubes in your Splawn (if you bought it new)? I had a stock Mullard re-issue EL-34 go pretty quick in my Quickrod. I don't think they use those these days for that reason.......
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I bought it second hand, but only a couple of months after orig purchaser bought it. The preamp tubes dont have a brand on them.. just say China and 12 ax7. The power tubes I think are Sinos. ( I think) Dont have it with me now.
 
Re: Tube amp help needed... PLEASE!!

Ascension said:
Bro take a pencil and tap lightly on your tubes if one is microphone you should hear it.
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ill try that with the power tubes over the next coupla days.. Ive tried rolling out all the preamp tubes already
 
Re: Tube amp help needed... PLEASE!!

BloodRose said:
ill try that with the power tubes over the next coupla days.. Ive tried rolling out all the preamp tubes already
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Just tap lightly on the glass if the tube is microphonic you will hear it through the speaker. There is a LOT of voltage in a tube circuit so use a wooden pencil and be careful man. I have had tubes just fail out of the blue usually after the amp was moved so there is a good chance you just have a bad tube.
Might also want to jump the effects loop as a dirty loop jack will cause that same issue. If it goes away clean the jacks and if it comes back run a jumper all the time or replace the jack. Had a couple amps over the years that would do exactly that when the effects loop jacks got dirty.
 
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Re: Tube amp help needed... PLEASE!!

Just checking...the speakers are ok, right? Flubby raspberry sounds when hitting low notes sounds like a speaker thing, to me.
 
Re: Tube amp help needed... PLEASE!!

hermetico said:
Failing PI or Drive tube does this!. As I said.
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I have not seen anything in this thread that suggests the OP has ruled out the speakers yet...hence, the "just checking". Best to rule out as many things as possible, I think, and speakers are another item in the equation that commonly fail.
 
Re: Tube amp help needed... PLEASE!!

FAC said:
I have not seen anything in this thread that suggests the OP has ruled out the speakers yet...hence, the "just checking". Best to rule out as many things as possible, I think, and speakers are another item in the equation that commonly fail.
Click to expand...

Thanks for the suggestion! I have the same problem with both a relatively new splawn 4x12 and an Avatar 2x12 cabs that are both fine if I run another amp thru them. So, it definately is the head in this case.
 
Re: Tube amp help needed... PLEASE!!

didnt notice anything odd tapping on the power tubes.. Lawdy... I sure hope its just a tube issue....
 
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