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DIY Stompboxes => Building your own stompbox => Topic started by: pjackso on January 22, 2004, 06:31:15 PM

Title: Replacement tube for my H&K Rotosphere???
Post by: pjackso on January 22, 2004, 06:31:15 PM
What brand of tube would you recommend as a replacement for the stock 12ax7 in my Hughes and Kettner Rotosphere?
Thanks...
Title: Replacement tube for my H&K Rotosphere???
Post by: Peter Snowberg on January 22, 2004, 06:47:00 PM
You may want to try more than just one. I have no idea what they came with, but any decent 12AX7 would be fine I'm sure. Try a JJ 12AX7 or a Sovtek 12AX7LPS.

Good luck,
-Peter
Title: Replacement tube for my H&K Rotosphere???
Post by: EdJ on January 22, 2004, 06:49:25 PM
I`d say JJ if you want to buy a new one;Phillips if you want to buy NOS and live in/near the Netherlands.
Greetings,Ed
p.s.do you perhaps have a schematic for that one?
Title: Replacement tube for my H&K Rotosphere???
Post by: bwanasonic on January 23, 2004, 12:44:22 AM
I seem to remember reading some people had good results with lower gain (5751 or 12AT7) tubes in there. I would try as many as you can, as different tubes behave differently in different circuits. The aforementioned JJ and Sovtek LPS are about the only current production tubes I  use.

Kerry M
Title: Replacement tube for my H&K Rotosphere???
Post by: The Tone God on January 23, 2004, 02:13:42 AM
I've tried a bunch of different tubes in a couple and to be honest I didn't notice a huge amount of difference be it NOS or production. Just about any decent tube, meaning no China or Sovtek WX* tubes, will do. The tube seems to be used only for some buffering and doesn't really do much.

As for a schematic I would imagine it would be way too sophisticated. There are two BBD sections (rotor and horn) and something like 9 quad opamps. Thats alot of stuff.

Just my opinion.

Andrew
Title: Replacement tube for my H&K Rotosphere???
Post by: pjackso on January 23, 2004, 11:36:50 AM
Andrew,
I'm not familiar with Sovtek WX* tubes???