SVT tube replacement question

[JimmyM]

Preamp tube on the way out, maybe?

 

[B-string]

Not that I know of, just the bias lights and i set them green, just back from red, with least hum....pulled two tubes...one from the original socket where the bad tubes was and no hum at 200 watts....just swapped right tube for left tube and we'll see. (Tubes are out of the box and matched).

Swapped tubes and now i get a buzz which increases with gain increase only, hum is loudest when gain and master are set to '0'...master only seems to affect buzz when it is at '0'.

So are we now working with a fresh set of tubes (one might have excessive heater leakage) or are we swapping used tubes into one triad?

 

[doomloop]

All the tubes are the new ones...all the pre tubes are new as well...gonna go through a swap process right now just to double check 'em....anything else maybe?

 

[B-string]

All the tubes are the new ones...all the pre tubes are new as well...gonna go through a swap process right now just to double check 'em....anything else maybe?

New tubes does not automatically mean "GOOD" .

 

[David Hayes]

I see where you posted after you put the matched 6 in. Did you fire the amp up and play it before swapping the preamp tubes?

 

[doomloop]

I see where you posted after you put the matched 6 in. Did you fire the amp up and play it before swapping the preamp tubes?

I thought I checked through each stage but now I don't recall hearing, or not hearing the buzz, so I guess I need to backtrack...

 

[David Hayes]

I thought I checked through each stage but now I don't recall hearing, or not hearing the buzz, so I guess I need to backtrack...

Maybe try putting the original preamp tubes back in and fire it up?

 

[doomloop]

I did that and still got the buzz...

I am just swapping left to right on the power tubes and sometimes the buzz is affected by all the knobs, other swaps it's just the gain knob!!??

The only tubes that I have not re-checked, after replacing with new ones, are the ones in the upper front chassis.

 

[doomloop]

Okay so no buzz with no signal and no buzz from guitar cable without bass...could this just be ground issues with my instruments or my home electrical supply? Seems awful loud but still...

 

[B-string]

Try swapping V1 in the front preamp section.

 

[doomloop]

Did a bunch of swapping still got the buzz from high gain or high volume...still buzzy with four 6550s but less pronounced.

Plugged in my freshly re0tubed laney aor 100 and got the same buzz with high gains or volumes and also some nice radio chatter.

Gonna bring the SVT to the studio for practice and see if I can blame my wall outlet electricity for the hum...unless someone thinks that running it is a bad idea....

 

[B-string]

Did a bunch of swapping still got the buzz from high gain or high volume...still buzzy with four 6550s but less pronounced.

Plugged in my freshly re0tubed laney aor 100 and got the same buzz with high gains or volumes and also some nice radio chatter.

Gonna bring the SVT to the studio for practice and see if I can blame my wall outlet electricity for the hum...unless someone thinks that running it is a bad idea....

This makes it sound like you have a bad instrument cable!

 

[doomloop]

This makes it sound like you have a bad instrument cable!

To be fair anything is possible. I will get it to the studio and plug into my regular gig stuff and see what happens....if it works out for me I may try to bring it to the gig tonight...if it remains overly buzzy I'll have to pass and keep on working on it or tech time...

 

[B-string]

The "radio chatter" is a pretty sure sign of a bad instrument cable.

 

[doomloop]

I only got the chatter with the laney and not with my svt...well...fingers crossed...been missing my tubes...

 

[JimmyM]

I have a feeling B-String is right. Might want to pick up a new cable on your way to your gig. Have fun!

 

[doomloop]

So...played it at practice...seems fine...new tubes are weird after having the old ones for so long...this is my first tube bass amp...the new tubes are BIG sounding, clean, lot's of headroom compared to what was in there...there is still a buzz when I'm plugged in and powered up with my gigging cables, etc...but quieter in my 810 than in the 2x12 I was using at home to test with the possibly bad instrument cable. Hoping this is normal, I think the same buzz may have been there before as well.

I sometimes get a loud pop or click when I hit my tuner pedal or memory boy...and a little cracklyness but I think it has to do with my AC adaptor and pedals maybe...

Played the SVT for the show too and it was fine...for some reason things sound a little 'trebly', not as raw and rough as the old tubes sounded...gotta get to dialing it in I suppose. So I'm running with the everything is fine attitude! Wanna square it away as i got a gig opening up for Dave Lombardo's band and I don't wanna 'blow' it...

 

[B-string]

Sounds like you're in good shape then if the hum at practice and the gig were the same as before. Yes new tubes will sound brighter, smoother, bigger and more powerful before breakup.

 

[doomloop]

Sounds like you're in good shape then if the hum at practice and the gig were the same as before. Yes new tubes will sound brighter, smoother, bigger and more powerful before breakup.

Man...I've been relying on that 'breakup'...it's like a whole new world....a new world of yummy tube goodness!!!!