tube rolling for bass?

[nickbaba]

OK so this is kind of a partner or appendix to my last post here about Chinese tubes...

I'm tube rolling my amp and looking to get a nice bass weight for listening to 70s dub, electronica etc

Currently using 2x JJ 12AT7 in the pre-amp stage. It's what the amp came specc'd with. I've heard they are less-bassy sounding tubes than 12AX7s, due to some technical differences ("the knee frequency of the coupling cap that is typically connected to the plate resistor will usually be much higher with the 12AT7").

Driver tubes are 2x SovTek 6SN7. Also have 4x SovTek KT88s as output tubes. I've heard that the JJ KT88s give a good weight on the bottom end. Also the Shuguang Treasure KT88s.

What would make more difference to the sound, changing the pre-amp tubes, or the output tubes? Or both?

[Arkless Electronics]

OK so this is kind of a partner or appendix to my last post here about Chinese tubes...

I'm tube rolling my amp and looking to get a nice bass weight for listening to 70s dub, electronica etc

Currently using 2x JJ 12AT7 in the pre-amp stage. It's what the amp came specc'd with. I've heard they are less-bassy sounding tubes than 12AX7s, due to some technical differences ("the knee frequency of the coupling cap that is typically connected to the plate resistor will usually be much higher with the 12AT7").

Driver tubes are 2x SovTek 6SN7. Also have 4x SovTek KT88s as output tubes. I've heard that the JJ KT88s give a good weight on the bottom end. Also the Shuguang Treasure KT88s.

What would make more difference to the sound, changing the pre-amp tubes, or the output tubes? Or both?

There is no truth to that.

You also cannot boost or extend the bass by changing valves. All hi fi amps are designed for a flat frequency response, the exact bass extension and undistorted power output in the bass is largely determined by the output transformer. Big is good! RC knee frequencies will usually be chosen to avoid core saturation of the transformer and also to avoid low frequency oscillation due to phase shift in the feedback path.
You may well get some change to the quality of the bass by changing the output valves, especially if the ones you are using are fairly worn....

[nickbaba]

Thanks for the solid info!