#1
Hello. I recently bought this tube pack from Eurotubes.

1 ECC83S Standard (ECC83S)
3 ECC83S High Gain (ECC83S-HG)
1 ECC83S High Gain & Current Balanced (ECC)

5 preamp tubes. 2 of them are placed within a "metal" container. Which of the tubes in this pack should be placed in them? Or does it even matter?

And do I need to BIAS the amp after changing? It's the same type of tubes that came with it.
Last edited by Skotland at Mar 11, 2016,
#2
It doesn't matter that much; or at least it won't hurt anything regardless of where you put them. You don't need to bias preamp tubes, just plug and play. Are they all the same brand of tubes?

I would probably put that "current balanced" one in the phase inverter position, which is usually the spot closest to the power tubes in most amps.

Other than that, the most important position in most tube amps is V1, the tube closest to the input jack. That position has the greatest impact on tone. If you want more gain, then one of those "high gain" tubes might sound better to you in that position. Then again, a hotter V1 tube may not actually sound better. I know with my 6505, it sounds much, much better to me with a lower gain 5751 tube in V1. So running a hot V1 tube is not always the be-all-end-all. The point is -- experiment. You won't hurt anything.

If the tubes are different brands, definitely try different ones in V1, you might find one that sounds better there than others.
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#3
It does not matter but usually if they only use the metal covers on one or two tubes those tubes are the V1 (often clean channel) and I guess V2 (dirty channel). So maybe the Normal ECC for V1 and the High-Gain for V2. Be sure to use that current matched for the Phase Inverter.

It all depends on your amp though. Look it up.

Preamp tubes do not need to be biased. Power tubes do need to be biased if your amp is fixed, adustable bias.
#4
Quote by Will Lane
It does not matter but usually if they only use the metal covers on one or two tubes those tubes are the V1 (often clean channel) and I guess V2 (dirty channel). So maybe the Normal ECC for V1 and the High-Gain for V2. Be sure to use that current matched for the Phase Inverter.

It all depends on your amp though. Look it up.

Preamp tubes do not need to be biased. Power tubes do need to be biased if your amp is fixed, adustable bias.


What's a phase inverter?
#5
Quote by Skotland
What's a phase inverter?
Quote by Roc8995
The phase inverter splits your signal into two identical but inverted halves, so the power tubes can amplify more efficiently.
https://www.ultimate-guitar.com/forum/showpost.php?p=7427128&postcount=1

Look it up if you want more information, but just that is just about all I can comprehend... I know some people suggest not to have a matched side PI, though.
Last edited by Will Lane at Mar 14, 2016,