6505+ Noisy Rhythm Channel

[ViolationComplex]

Hi all - I had a good search through the forums but couldn't really find anything that answered my question... I hope you can help!

I bought a 6505+ head a couple of weeks ago but noticed at practice that the clean/rhythm channel is extremely noisy. When pre is at about 5.5/10 and the post at about 3.5/10, I get this really loud low rumble/hiss when not playing. It basically sounds like the noise you hear when you're on an aeroplane. The wierd part is that when I change to the lead channel (pre 6, post 3.5) it's not there at all.

I'm using a 6505 slanted 4x12. I hear this even WITHOUT the guitar plugged in.

Is this normal? Or do you think there might be something up with it?

I use an NS2 which helps, but the amount of noise is just stupid...

Thanks!

 

[Notuern]

I never had a 5150 so I cant say if this is normal or not, but I know you can get this from bad tubes.

Edit:
Oh, and bad biases.
Maybe there is a bad match set of tubes in your amp?

 

[Kazrog]

This is how that channel has been for me, in my experience. Slightly better since I replaced the stock tubes with JJ/Teslas (both in the power and preamp sections.) Having a Boss NS-2 is essential with this amp.

 

[greyskull]

my 5150 is noisy as fuck without anything plugged in!

 

[Saculus]

Noise gate in effects loop or its hiss central.

 

[nwright]

The rhythm channel should be nowhere near as hissy/noisy as the lead channel on the same pre/post gain settings.

I'd try a quick preamp tube swap and see if that takes care of it.

Looking at the pre tubes from the back of the amp, the tubes that effect the rhythm channel are the 2 farthest to the right. The farthest 1 to the right is V2 for that channel, the one just left of it is V1 (for both channels). If only the rhythm channel is noisy, I'd start with the farthest to the right, V2.

 

[ViolationComplex]

Great - thanks for the replies folks. I'll see if I can take a look at a pre tube change.

(Being a tube noob)Can anyone point me in the direction of a good thread on valves. I've heard lots about JJ's and Teslas, but I'm not sure what I'm looking for.

Also, with the NS-2, how are people hooking up using the 4 cable method? Guitar > Input, Output > Amp In, NS Send > FX Return, NS Return > FX Send

Thanks again

 

[Katau]

Here is a decent place to get tubes...and a few options too:
https://ssl.eurotubes.com/cart/index.php?page=view_products&category_id=8&sub_category_id=40

 

[Gnash]

So I've had the bias mod all the new tubes, and I still have that "hum", even with ns2. I was thinking of exchanging it, thinking a transformer was bad or somethin. Does everyone seem to have this hum? I run my gain at 5-6. It's real annoying, and i certainly can't track with this head (6505) The bias mod is pretty simple, so I will probably exchange for new. I'll be pissed if the new one has the hum. haha

 

[Gnash]

Also, with the NS-2, how are people hooking up using the 4 cable method? Guitar > Input, Output > Amp In, NS Send > FX Return, NS Return > FX Send

Thanks again

wow i've never tried this. sounds like overkill.

 

[ViolationComplex]

wow i've never tried this. sounds like overkill.

Haha maybe, but if your heads as noisy as mine...

Well I heard by doing this you have a noise gate before and after the pre. Before killing guitar noise and feedbackm, and after eliminating hum/hiss from the amp itself.

 

[Metaltastic]

Hmm, like Decimator Pro Rack G style (though I doubt the NS-2 works as well, naturally)

 

[nwright]

So I've had the bias mod all the new tubes, and I still have that "hum", even with ns2. I was thinking of exchanging it, thinking a transformer was bad or somethin. Does everyone seem to have this hum? I run my gain at 5-6. It's real annoying, and i certainly can't track with this head (6505) The bias mod is pretty simple, so I will probably exchange for new. I'll be pissed if the new one has the hum. haha

I have a hiss gets louder as you turn the gain up, since it IS a high gain amp, but I have no hum at any gain or voume level.

 

[bryan_kilco]

Haha maybe, but if your heads as noisy as mine...

Well I heard by doing this you have a noise gate before and after the pre. Before killing guitar noise and feedbackm, and after eliminating hum/hiss from the amp itself.

I have tried the same setup, seems to work ok. I have a Mesa Mark IV, though.
Lately the lead channel has been getting noisy. Just retubed the whole thing over the summer. Is it that time allready?!!

 

[Metaltastic]

Lately the lead channel has been getting noisy. Just retubed the whole thing over the summer. Is it that time allready?!!

Almost certainly not for the preamp tubes, but as for the poweramp tubes, well, it depends how much you use it!

 

[nwright]

^ you could also maybe have a bum pre tube.

 

[bryan_kilco]

Almost certainly not for the preamp tubes, but as for the poweramp tubes, well, it depends how much you use it!

well, it gets used about a few times a month, on average. we JUST got a practice space (finally, its been years) and we play shows about once a week, on average. practice is starting to work out a schedule....a few hours each time we jam.

it also did this thing, where....at our last show, the volume would go from loud, stage volume, then drop, almost un-noticable.
Mark from Lamb of God actually responded to post and told me I have a bad Master Volume pot.

but....as for tubes, Im running GT powers and Sovtek pres. One preamp tube is actually dimmer than the rest.....hmmm.....