Tubeswitch ...

[Panamark]

Originally posted by Eyes
Yup, just came across that word Svetlana last night at peavey.cum ... just a distributor it looked like ... sorry Pana

No wucking forries !!

[Eyes of the Night]

Originally posted by ELVIS
I bought my first vintage Marshall head in 1987...

By 1990, I edcuated myself on every major technical aspect of these, and other tube amp circuits...

It's not rocket science, by any means...

Ah, true that my bre but that for me right now would be like cramming for finals at college n' shit ... even though I went to tech school ...

In 90' I was in 10th grade just starting with 1 year of learning chords ... trip

You saw my Wolfie right? Ain't no way I'm touching my 50II!

[Nitro Express]

If you don't know what you are doing, you have no business opening up a tube amplifier. The stored voltage in the capicitors can kill you even when the thing is unplugged. Rebiasing a Marshall required that you open up the amp. You can send yourself to the Pearly Gates or Hell real quick if you touch the wrong connection. You can change the preamp tubes yourself but everytime you change the power tubes you need to check the bias. Like I said above, too low of a bias setting will make your amp sound dull and lifeless. It's smart to have a technitian familiar with guitar amps change the tubes and check your bias for you. Like I said, some technitians just set the potentionmeter to where they are reading a certain voltage draw but this might not give you optimum sound. Everytime you change tubes, the voltage draw will change because tubes differ. That's why it's best to use a matched set of tubes.

What I'm getting at is the tubes in you amp might sound just fine but the bias is set wrong for them. Sometimes people think it's the new tubes that fixed the problem but in reality, the new tubes run better with the bias setting.

Some amps don't have an adjustable bias like a Marshall. They have a set value resistor instead of potentionmeter. This is called a fixed bias amp. The only way you can change the current draw is to try tubes until you find a set that work the best. These amps are best avoided.

You really can't go wrong with buying a Marshall for this reason. Also there are people who know how to work on them and mod them if you want.

[ELVIS]

Originally posted by Nitro Express
Some amps don't have an adjustable bias like a Marshall. They have a set value resistor instead of potentionmeter. This is called a fixed bias amp. The only way you can change the current draw is to try tubes until you find a set that work the best.

That's not true.

Any amp can be biased. The resistor values can be easily changed by any qualified amp technician...

[BrownSound1]

Fixed bias amps simply cannot have the right biases for all tubes, so the first mod I would have done to one is installing a pot so I could change the bias as needed.

[Nitro Express]

I never could figure out why they put fixed resistors in some amps instead of a pot. It doesn't seem like it saves that much money.

[BrownSound1]

It saves the manufacturer time and money, in that they don't have to pay someone to bias every amp that goes out the door.

The idea of having an amp that you don't have to bias manually is great....however I would rather see them design some type of self-biasing circuit, instead of just popping a fixed value resistor in there to try to cover a wide range.

[Eyes of the Night]

Okay, I ain't digging the EL34R's ... time for another switch too ...??? Well let's look here ...


Power Tube Comparison Chart (All Tubes #5)
Tube Type Bias Comments
GT-6V6C -46vdc Warm, strong, nice edge.
GT-6V6R -48vdc Smooth, warm, slightly dark.
GT-KT66HP -61.9vdc GT design. Exact NOS spec, warm bouncy tone, great highs.
GT-KT66C -61.2vdc High power, warm tone balance.
GT-6L6GE -61.0vdc Exact GE design using their original tools. Strong, articulate musical.
GT-6L6R(B) -56.0vdc Slightly aggressive, harder edge yet still warm.
GT-6L6R2 -56.0vdc New Russian design, strong, hard tone.
GT-6L6C -54.3vdc Crisp, solid, ideal for Country Rock.
GT-6L6S -49.7vdc GT design, highest power 6L6, strong bass and highs.
GT-E34LS -50.5vdc GT design, most powerful EL34, big bass, crunchy top.
GT-EL34C -47.3vdc Looser, crunchy and slightly less bass.
GT-EL34R-49.9vdc Linear response with harder edge.
GT-EL34R2 -49.9vdc Linear response with harder edge.
GT-6550C -68.2vdc Soft distortion, round and warm.
GT-6550R -66.0vdc New 6550A copy, less power shorter life.
GT-KT88SV -69.1vdc GT design, replicates Genelex




Ookay ... leaning towards these ...

GT-6V6R
GT-6L6GE
GT-E34LS



Hmmm ...


Hey BS1, you get a 5 star for that list my bre ...

[kentuckyklira]

Originally posted by Denny
EL34 tubes are ok.........5881's are WAY better, IMO.

Real men play EL34s!

[Denny]

Originally posted by kentuckyklira
Real men play EL34s!

My Amp (a Soldano) has 5881's and it makes a JCM 800, JCM 900 and a 5150 look like a piece of shit.

Have a Nice Day™