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Faerwald

Spider Valve MkII HD100 tube issues - questions.

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Hey everyone.

 

So this is my first tube amp, and it was working great so far.

However, Yesterday during band practise, after it had been on and working perfectly for two hours, the volume suddenly dropped. When I checked the amp to see what was going on, I noticed that one of the tubes (the one on the left) was way hotter than the others. when I turned down the volume, where was a small lightning inside the tube, and then no sound. From what I've gathered from the internet, the tubes weren't paired or biased properly. When the amp is on, the other tubes light up normally.

 

Anyway, when I bought the amp, the people at the store had only two tubes installed (the two in the center), to cut the output down and make it playable in the store.

 

I wanted to know if there is any specific manipulation to do in order to do that. (I have a gig in 4 days and I probably won't have neither time nor money enough to have the tubes changed and the amp biased before then). 

 

 

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As I recall, impedance doubles when you take two tubes out of a four tube push-pull power amp....Not recommended...

 

4 ohm output becomes 8 ohms nominal

8 ohm output becomes 16 ohms nominal

16 ohm output becomes 32 ohm nominal

 

If you do this, and 8 ohm load in the 4 ohm output is technically, the safer bet....Still not something I would do...

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It may be only that it's time for a tube change out and bias. Good idea to do that once every

12-18 months if you're a performing musician. Have it checked out at a Line 6 authorized service

center in your area, that knows tube amps.

 

Sales person should have never pulled two tubes out of it,...  much less the wrong two tubes. It

offset the push-pull symmetry. That and how long they've been in the amp is probably why the

one tube was hot.

 

Don't try to deal with it yourself, it hurts when you get zapped. Take it in to a service center, have

the right tubes put in and biased by a tech.

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I'm definitely getting a tube change and bias, I was just wondering if the "two tubes out" solution would work as a temporary solution in case I could not get it done before the upcoming gig.

 

I guess I'll just have to find a tech to do it tomorrow

 

Thank you for your answers!

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"I was just wondering if the "two tubes out" solution would work as a temporary

solution in case I could not get it done before the upcoming gig." ----

 

No!

Don't do that.

 

These aren't our grandfather's tube amps, these are mixed technology amps,

you can't get away with this sort of thing like we used to in the old days. They

are not designed to do that.

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And use the specified Sovtek 5881WXT, matched quartet tubes.

 

No JJ's, Mesa's or Groove Tubes,.... if they are biased the same

as the 5881WXT, there will be problems, the characteristic curves are

not matched close enough for use in this amp.

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Be sure to use the correct impedance output for the cabinet that you are using.

They have to be matched or the tubes and circuitry will get stressed,... and then

it will end up on a technician's bench. And that's no fun.

 

Keep your fingers out of the inside of the amp,... even with the power off, a capacitor

can discharge into your hand, and that hurts like hell.

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And use the specified Sovtek 5881WXT, matched quartet tubes.

 

No JJ's, Mesa's or Groove Tubes,.... if they are biased the same

as the 5881WXT, there will be problems, the characteristic curves are

not matched close enough for use in this amp.

 

This is a contradiction....You must be new...

 

http://line6.com/supportarchivenew/thread/74881/

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No, I'm not new,... the thread is out-of-date. I'll let Dave know, thanks.

I've been dealing with Spider Valve since the beginning, been dealing

with tubes and tube amps for more than four decades.

 

The characteristics curves of the JJ's, Mesa's and Groove Tubes

are not close enough. If those are biased the same to the

bias settings for the 5881WXT's,... then the amp ends up on

my bench with problems. Can't use the same bias settings on these

other tubes as with the 5881WXT.

 

I see too many come back because of the wrong tube and/or bias settings.

This is a mixed technology amp. You can't get away with the same

sort of things we used to get away with for Marshall amps with 6550's

in them.

 

These amps are not as forgiving as the tube amps of yesterday-years.

It's a Bogner hot-rod.

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New Sensor (Sovtek) 5881WXT is actually a 6Π3C-E and nothing like a real 5881....It's more like a 6L6 actually.....A JJ 5881 is actually a real one...23 watts and SV's plate voltage is too high for it...a mistake to put real 5881s in an SV....

 

The following branded tubes are the same 6Π3C-E bottle......

 

Fender 6L6 Precision Matched Tubes (5881WXT)

Fender GT-6L6B or 6L6R (5881WXT)
Groove Tubes GT-6L6B or GT-6L6R (5881WXT)
Marshall 5881 (5881/6L6 WGC)
Mesa Boogie STR425 (5881/6L6 WGC)
Ruby Tubes 6L6R (5881/6L6 WGC)
Sovtek 5881/6L6 WGC
Sovtek 5881WXT

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The Sovtek 5881WXT is what Rheinhold Bogner spec'd for this one (Spider Valve series).

The Sovtek 5881/6L6 WGC doesn't have the cup at the bottom which created problems with tube retainers

so we don't use those anymore.

 

People want the crunch of a Mesa tube, unfortunately too many with Mesa tubes come back with problems.

JJ's and GT's also come back to us with problems, and things like the bias being way off-spec.

 

The Sovtek 5881WXT is what Rheinhold Bogner spec'd for this one (Spider Valve series). There are interactions

between the digital portion and the tube portion, such that, it is not as forgiving as old 60's as 70's tube amps.

You can't get away with the same deviations with these as we used to with older tube amps.

 

 

We have our tubes go through some extra scrutiny.

Best to stick with the specified tubes,... less problems that way.

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