Oscillation in tubes/Power amp questions

newamerikangospel · 10-11-2007, 08:32 PM

I am using my bass players blue voodoo (old model) for a power amp for my gnx, and it is emitting a noise (not the normal loudness noises). To me it sounds like oscillation. Since I am running from the effects return up, I am bypassing the preamp, so would this be all power amp, or could this be a preamp tube?

Since I am using this is a power amp only, what would one suggest for power tubes. From the general conscensus on this board, 6l6s are less harsh, and it has 6l6s in it right now (so it wouldnt need any type of work done to fit them). From what I have heard from several amps with them, ruby 6l6s seem to focus the mids. Opinions on different brands or other type of tubes (el34s, ect)

thadood · 10-11-2007, 08:55 PM

The effects loop may have a preamp tube buffer. Check into it.

newamerikangospel · 10-12-2007, 01:17 AM

But a preamp tube (say running in the v1-v4 socket) wouldn't cause the problem if I am running just power amp?

This is the first time I have actually played around with a tube head other than at GC. Im a t00b n00b.

7 Dying Trees · 10-12-2007, 07:27 AM

try plugging a jack into the FX send that goes nowhere. Maybe even max out the send level in case it's a fx mix control...

Popsyche · 10-12-2007, 07:30 AM

The power amp section isn't just the power tubes. There is likely at least one of the "preamp" tubes involved as an inverter stage, and like was said before, a tube buffer stage. Does that amp sound fine when played normally?

newamerikangospel · 10-13-2007, 12:00 AM

Im not sure, I will take an indepth look at it tomorrow. I was late to practice, and we just through the head on top of the cabs, miced it, and started running through the songs we have so far.

And with the exception of the presence knob (again had almost no time to tweak), the fx return has no post controls. There is a 12db switch for the fx loop, other than that nothing.

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10-11-2007, 08:32 PM	#1 (permalink)
newamerikangospel HA HA!...Avatar! Join Date: Oct 2006 Location: Oklahoma Posts: 1,226 Real Name: lepsognakiremaw Main Seven: Schecter Gryphon Rig: GNX>H&K4x12-Hrtk2x15 Thanked: 13	Oscillation in tubes/Power amp questions I am using my bass players blue voodoo (old model) for a power amp for my gnx, and it is emitting a noise (not the normal loudness noises). To me it sounds like oscillation. Since I am running from the effects return up, I am bypassing the preamp, so would this be all power amp, or could this be a preamp tube? Since I am using this is a power amp only, what would one suggest for power tubes. From the general conscensus on this board, 6l6s are less harsh, and it has 6l6s in it right now (so it wouldnt need any type of work done to fit them). From what I have heard from several amps with them, ruby 6l6s seem to focus the mids. Opinions on different brands or other type of tubes (el34s, ect)

10-11-2007, 08:55 PM	#2 (permalink)
thadood 'Das brootal. Join Date: Aug 2006 Location: Memphis, TN Posts: 542 Real Name: Matthew Main Seven: Carvin DC727C Rig: El Diablo -> Vader Thanked: 17	The effects loop may have a preamp tube buffer. Check into it. Your ass here!

10-12-2007, 07:27 AM	#4 (permalink)
7 Dying Trees Sarcy English Twat Join Date: May 2004 Location: 7th Ethereal Plane of interstellar hell, Innit Bruv, Safe, London, UK Posts: 6,579 Real Name: James Main Seven: UV7PWH / UV7BK / RG2027 Main ERG: 10 fingers of metal death Rig: Triaxis->TBR5/VHT UL Thanked: 77	try plugging a jack into the FX send that goes nowhere. Maybe even max out the send level in case it's a fx mix control... The Chaos has come: www.chaosanct.com

10-12-2007, 07:30 AM	#5 (permalink)
Popsyche Beer Sewer Join Date: Mar 2006 Location: Bethlehem, PA Posts: 4,973 Real Name: Bill Main Seven: UV777GR, UV-MC Noah James Rig: Old Marshall, Fender Thanked: 208	The power amp section isn't just the power tubes. There is likely at least one of the "preamp" tubes involved as an inverter stage, and like was said before, a tube buffer stage. Does that amp sound fine when played normally? If electricity comes from electrons, does morality come from morons? New Bandsite! http://www.myspace.com/cupsofsobriety www.myspace.com/wfkoehleriii http://mysite.verizon.net/vzeo7bjr/index.html

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10-12-2007, 01:17 AM	#3 (permalink)
newamerikangospel HA HA!...Avatar! Join Date: Oct 2006 Location: Oklahoma Posts: 1,226 Real Name: lepsognakiremaw Main Seven: Schecter Gryphon Rig: GNX>H&K4x12-Hrtk2x15 Thanked: 13	But a preamp tube (say running in the v1-v4 socket) wouldn't cause the problem if I am running just power amp? This is the first time I have actually played around with a tube head other than at GC. Im a t00b n00b.

10-13-2007, 12:00 AM	#6 (permalink)
newamerikangospel HA HA!...Avatar! Join Date: Oct 2006 Location: Oklahoma Posts: 1,226 Real Name: lepsognakiremaw Main Seven: Schecter Gryphon Rig: GNX>H&K4x12-Hrtk2x15 Thanked: 13	Im not sure, I will take an indepth look at it tomorrow. I was late to practice, and we just through the head on top of the cabs, miced it, and started running through the songs we have so far. And with the exception of the presence knob (again had almost no time to tweak), the fx return has no post controls. There is a 12db switch for the fx loop, other than that nothing. Last edited by newamerikangospel; 10-13-2007 at 12:01 AM. Reason: Automerged Doublepost

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Oscillation in tubes/Power amp questions