• WARNING: Tube/Valve amplifiers use potentially LETHAL HIGH VOLTAGES.
    Building, troubleshooting and testing of these amplifiers should only be
    performed by someone who is thoroughly familiar with
    the safety precautions around high voltages.

first tube project


2005-08-11 11:30 am
Looking for a reasonably simple SE design to build as a first project.
Have some XP with electronics and diy, and am currenly on a learning curve re-building and designing tube circuits - not yet knowledgable to design own, but ready to build one (especially as my power amp has been nicked by scrotes).
have a budget of around £300 to spend over here in UK.
Power not too important as it will be driving some Rhedeko 115's with a sensitivity of 96/dd - but will probably need 5+ watts to really move air.Would sooner have sweet lo-power rather than high-grunt!
Would prefer schematics for amp AND psu - any ideas?
Thanks in advance chaps,
Do a search here for Mikael's SE KT88 schematic. I built this as a pair of monoblocks and have been very happy with the result. I had been using them with a preamp but recently gave a passive pre (just a volume pot and source selector really) a try and find that I like that combination just as well.

I used James 6123HS OPTs and Hammond iron for the PTXs and chokes.

Here is a drawing for the PS I used with mine. Note that I built monoblocks so there are two of these power supplies. The Hammond PTX I used doesn't have the current capacity for two channels so you would need to beef that component up. The rest should work I think.

Oops, I forgot. Mikael was estimating 4-5 watts per channel. I hooked up the scope a couple weeks ago and ran some tests with mine and I'm getting somewhere around 6 watts.


  • kt88 power supply schematic.jpg
    kt88 power supply schematic.jpg
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Yup, go for this one!

Sweet sounding, highly detailed, excelent sonics, though i need a preamp on some CDs (that's a different story), can be built in an afternoon, as long as the chassis is ready :p
I'm using a Valvo E88CC (if, like me you have difficulty in sourcing the 6N1P), and it gives a little "fatter" sound, unlike Philips E88CC.
The only mod i did to Shermans (thanks ;) ) PSU (powering both channels) was replacing the 100uF cap for a 220uF - 5mV ripple!

No changes made, Sherman.
I asked for help at Edonion to see if there was any need to change components on the E88CC side, but they assured me i wouldn't need to.
So far, so good. I tryed a cheap PCC88 first, but the gain was a tad low due to a bit starved filament. Happy now, though :D

Happy mod Sherman!