Swapping preamp tubes on F-50 for lower gain

[pulteney]

Hello there, first post, been lurking for a while

So, I adore the clean channel of my F-50 but don't need that much gain on channel 2. Read about swapping preamp tubes but I've never done it.

1. That affects channel 1, too, right?
2. Do I need to change all 4 preamp tubes or just V1?
3. Have you tried any of these? https://reverb.com/news/how-to-improve- ... tube-swaps

Thanks for your insight!

[Don]

If the F-50 is like the F-30, then V2A (pins 1, 2 & 3) is the first gain stage for the lead channel. V1A follows the tonestack on the lead channel. You could install a JJ ECC832 in V2 or both V2 and V1 to lower the lead channel's gain without affecting the rhythm channel.

The ECC832 is like an ECC83 (12AX7- gain factor 100) on pins 6, 7 & 8 and an ECC81 (12AU7- gain factor 20) on Pins 1, 2 & 3.

I've used the JJ ECC823 (the opposite of this tube) in Mesa DC and Marshall DSL amps for this purpose and it worked well.

[pulteney]

Thanks! First time I've ever heard of this tube.

I was thinking of swapping V2 for a 12AY7 and V4 for 12AT7 but I'll definitely give yours a spin. Thanks!