Tubes - Please Educate Me!

[Jarick]

I've got an Orange Rocker 15 Terror and I've forgotten everything I knew about tubes.

I think all the tubes in here are stock, which appear to be JJ's. There's three 12AX7's and two EL84's.

The amp has two channels, dirty and natural. The natural channel is super clean and only has a volume control. Dirty has gain, volume, bass/middle/treble, so I'd like to use that as basically a single channel with pedals out front. The dirty channel is pretty quiet until about noon after which it hits full volume and gets really distorted with kind of a harshness.

Let's say for this particular amp I want to lower the amount of gain and smooth out some fizz in the high end. If I swap out say the V1 preamp tube for something else, would that move in that direction? Any suggestions if the current preamp tube is a common JJ 12AX7?

 

[Achilles]

A Look at Preamp Tube Gain Factors

In this blog John Templeton will show you how preamp tubes with different gain ratings can affect your amp and help tweak your tone!

blog.thetubestore.com

Quick word of caution: Tube swapping can quickly turn into a rabbit hole all unto itself.


You've been forewarned.....

 

[Achilles]

@Jarick

The Benson Vinny Reverb came with a preamp tube I'd never heard of before and it's not mentioned in the previous article.

12DW7

Brief discussion here:

12ax7 vs 12dw7 or 7247

Hey Folks, I am studing the schematics for the dyanco st-35. It requires the 7247(12dw7 sub I believe). I was cross checking it to the 12ax7 and I don't really see a difference. Can anyone tell me if there is? What is it? Also, what would you recomend as the "premium" tube for that...

audiokarma.org

 

[Desertdweller]

Here's my recommendations:

Lower noise floor & better attack - Tung Sol 12AX7 in V1
Less gain - read the manual to find out whichever tube is the main driver for the channel you're looking to reduce gain in. Replace that 12ax7 with a 12AU7. You will notice immediate drop in gain going to this tube, and you may like the sound more. I've used this to tame the red channel on an EVH 5150 III and it works perfectly, as that channel normally maxes out the gain way early at 9 o'clock on the dial. Using this tube in V2 of that amp made it so the full gain on that channel was at 2 or 3 o'clock instead of so much earlier.

You can also experiment with a Sovtek 12ax7 LPS if you want to mess with the midrange character a bit.

Having said all of this, the tube that is going to give you what you want the most is that 12au7 and you may want to prioritize that one, as it drops the gain significantly.

 

[la szum]

Sometimes dropping gain also results in less top end brightness and definition.
Can make an amp sound downright dull, especially when messing with V1, which
is where your primary tonestack is.... errr.... amped up. .

Look forward to you reporting back. A JAN 5751 would be my recommendation
for a happy middle ground in going down the gain reduction rabbit hole.

 

[AFKAEjay(retired)]

Why does inserting a tube with less power result in anything different then simply reducing the gain with the gaincontrol?

 

[la szum]

Not all 12AX7s sound exactly the same. Those differences become more magnified when discussing
different preamp tube types, in my experience.

Glenn Fricker this comment all you want!

 

[Achilles]

Not all 12AX7s sound exactly the same. Those differences become more magnified when discussing different preamp tube types, in my experience.

And brands.
And batches.
And factories.
And your ears throughout the day.

Hence........

 

[laxu]

IMO the JJ ECC83S is one of the worst sounding production tubes out there. Every time I've put one in an amp it has made it sound worse compared to other tubes. It manages to sound dull yet fizzy at the same time somehow.

JJ makes other tubes that are better, like the ECC803S or the ECC83MG. The 803S is bright but can also be microphonic so it doesn't necessarily work always. The MG is a solid option, so is Tung Sol 12AX7.

I'd advice just buying some preamp tubes, trying them out and check if you hear a difference. If you do, great your amp sounds better. If not, you now have some spare tubes.

Phase inverter tube swapping is IMO not worth it.

 

[TubeStack]

Just get a Fractal.