Hi all,

I am new here and a novice guitar player playing a bit of Blues, Jazz, Classic Rock.

I had the opportunity to buy a H&K Tubeman MKI secondhand for 100 euros. I like some of the sounds I can get out of it a lot but the pedal lowers my guitar volume instead of giving me more gain. This happens on all three outputs (Guitar Amp/Mixer/Power Amp).

The controls work well, so I am thinking it is maybe the tube that needs to be replaced. The tube in it is a Electro Harmonics 12AX7 or ECC83. As I don't like the "Rock" setting (the pedal has four modes: Jazz/Funk/Blues/Rock)

I would like to have a smoother sound. Is a 12AT7 or 12AU7 as I read often on the internet a good replacement?

Will this solve my gain problem?
Last edited by kaouki at Sep 18, 2012,
I'm not too familiar with the pedal and can't find any schematics on it. If it is like a regular tube preamp (high voltage - not starved plate), avoid the 12AT7. It has very harsh distortion characteristics.

The tubes I would recommend you try to get are either the 5751 or a 12AY7. I don't know if this would make the pedal any louder since I can't find a schematic and certainly don't have one in front of me to test.
When looking for the schematic I maybe found the answer. As Thomas Dunham stated on his Picassa gallery:
"The greatest tube pedal ever! The components are top notch except the pots which I have replaced twice already, otherwise very nice quality. Power supply is 12V A/C but when my power supply died, HK sold me a replacement 14V and threw in a set of said mini pots."