Newb question about tubes at low volumes.

[Inazone]

Hopefully this isn't the dumbest question ever asked, but here goes...

[img]/images/graemlins/help.gif[/img]

I've been playing old single-channel Peavey Classic tube combos at gigs for the past couple of years. These amps have solid state preamps and tube power amps, with no distortion of their own other than a little "grit" at high volumes. I use a distortion pedal to get my desired tone. No problem there.

I'm in the process of putting together two new rigs, one with an Peavey VTM-60 tube head (12AX7/6L6) and the other with a rack preamp into a tube power amp. The power amp is a Peavey Classic 60 with 6L6s and 12AX7 "drivers". I don't know what the 12AX7 drivers do specifically. Since I've just been testing out the head and rack setups at home (apartment) so far, I have to play at very low volumes.

I'm noticing some volume fluctuation when running my pedalboard or rack preamp through either the head or power amp, some "warble" if you will. I don't notice this issue if I plugged my guitar directly into either of them, nor do I notice it if plugging the pedalboard or rack preamp into a solid state amp played at the same volumes. I had the same issue with the rack preamp running through a friend's power amp at low volumes. I have tried all different cables, different guitars, and verified that all my settings are correct. I removed anything between the rack preamp or pedal and the amp.

If turned down below a certain point, will a tube power amp not be able to effectively do its job, causing the volume to fluctuate, to "warble"? I find it hard to believe that my Peavey head and power amp AND my friend's VHT power amp would all malfunction. It's not the preamp (as far as I can tell) because it worked fine at low volumes into solid state amps and a Digi 001 interface. I'll be trying it through one of my tube combos at gigging volumes during practice, but I'm trying to educate myself a bit here in the meantime.

[Dreamland_Rebel]

Re: Newb question about tubes at low volumes.

aww man, just wrote this great response and i just lost it all!

so i'll just spit out the gist of it.


each tube amp has its "sweet spot" as far as volume goes and that is based on your settings, its size, its design and construction. etc. etc.

smaller tube amps will get you better tones at lower volumes.

the best way to achieve good high wattage tube amp tones at lower volumes is to use an atinuator (sp bad) like the THD Hotplate.

so yes, power tubes will not effectively do their jobs at lower volumes.

[Cleveland Metal]

Re: Newb question about tubes at low volumes.

Gads... Yes, a tube won't be saturating at low levels, but turning down a tube amp will NOT make it warble or anything like that.

I run a VHT 2150 which is TWO 150 watt amps in a stereo config, and play it daily at living room levels and it sounds awesome. Owned tube amps since the 70s and always played them at bedroom levels and they are fine.

[skorb]

Re: Newb question about tubes at low volumes.

Inazone I'm glad you asked that question as I wanted to know that too.

[siggy14]

Re: Newb question about tubes at low volumes.

i kinda of had the same problem, almost sounds like your amp takes a volume hit for a breif second, right? If this is the case i narrowed it down to one of two things. Either i had a crappy or going bad patch cord/cord, or because my tubes were biased way to cold. I did change the cord and the problem seemed to go away, but it was intermitent so i could never be so sure. The next day i replaced the tubes and biased them right and i have never had the problem again.

Now here is the twist, this would only happen on my JCM800's that were way out of bias, never happened to my bogner, so i am not sure if it was the tubes or the cable, could have been either. Since it was intermitent it could just mean it never happened when i was plugged into the bogner.

[Inazone]

Re: Newb question about tubes at low volumes.

Just a quick update. I took the rack preamp to my practice space and ran it through the power section of my Peavey Classic 50 combo, playing at normal "live" volume. No problem at all, sounded fantastic. I don't have any particular reason to suspect that my amps at home are bad, but I'll revisit that later. I really just wanted to make sure my rack rig was going to "play nice" in a live setting.

Cleveland, I'm thinking that I was running the volumes so low at home that I was hitting that point where the amp's volume is in the "under 1" area, just barely loud enough to be clearly audible. I don't expect the tubes to saturate at such a low level.

I'm starting to suspect that maybe I had a bad cable after all, because at my practice space I use different cables, except for patching my rack components together.

[Cleveland Metal]

Re: Newb question about tubes at low volumes.

Oh, I wasn't saying "you" were expecting the tubes to saturate. I was basically responding to Dreamlands comments that at low volumes tubes weren't running efficiently.

I guess I'd have to wonder about cables as well. This is certainly an odd situation. Considering multiple amps amps are involved. Just odd it doesn't do it with the soild state stuff. I'm kinda baffled at that aspect of it.