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(click photo to for some more photos)

January, 8th. 2010

 Yes, yes, yes I know that I raped another classic, mea maxima culpa :-)
 BUT beside the fact to be a classic there is/was . . . . NOTHING !

The reverb unit is classical, analogue and for todays demands ...  CRAP !
Maybe that a musician looking for a vintage reverb sound has another view on that . . .

Also one channel dropped from one minute to another.
So I decided to make use of the chassis for something new.

OK, it's not really new. At least the Hongkong based seller was claiming that
the PCB is a modded version of the original famous SL-1 MK2 preamp,
Really don't know if that's the truth, because I couldn't find any net-source for the original schematic.
Nevertheless after having a look at the schematic I was wondering if it could really be true that such a famous brand
did all the stuff that I'd never do in my amateur circuits:
 12AU7 feeding a 12AX7 -stage feeding a 6DJ8 cathode follower made me VERY inquisitive.

So I ordered the PCB at a more or less ridicoulus 17 incl. shipping
(ok, now, after I know the quality I can really say ridicolous. The price/quality ratio is very good)
and - after it arrived - decided to give it a try.

The sound: It's really ok. (Please keep in mind that I'm a cool, calm, reality
driven German and I think that there are only very few things that I hate more than
the BritonZ & AmericanZ "BRILLIANT" & "EXCELLENT" statements for any pissed stuff and absurd vanities.
Other things on my Top10 to hate scale are the phrases of the hifi & hiEnd-press
So it's very likely that my "It's really ok" stands for a higher quality than
thousands of "brillant"s and "excellent"s from other sources)

 Not as musical as the Aikido but it seems to have more emphatic details.
 (It's still burning in, so it may be a little too early to give a final satement/judgement).
All in all for my taste it's the most hifi-esque preamp I build so far.
Neither meant positive NOR negative. Just as a fact.

For now I don't have any feeling that I did something wrong or wasted my time.
I'm just listening to music with that box and enjoy it.

Builders advice:
I used the powersupply described in the "BarBar" preamp section and stepped it down to 260V with another 3K3 R.
The circuit has way too much gain, so Ive added voltage dividers at the output.

I ordered the PCB via  from
His/her/their webstore is

The guy has also to offer many other PCB's for so called classical/famous tube audio circuits.
If you don't want to try such "exotic" designs as I did,
 (There is a DIY audio thread where they really piss on the SL1 circuit - that I can't confirm :-)
you may try onother PCB. They're not too expensive and much easier to build than hardwired circuits
especially for beginners.

As I already said: Esp. for beginners, to build circuits based on PCBs
may be the silver bullet to start with this fine hobby of DIY-tube-audio.
This is OF COURSE also true for the AIKIDO, however you need more technical skills
to understand the AIKIDOS user manual and hence to build it.

As alway stay tuned and ...
Feel free to contact me, if you have any questions, suggestions, comments etc.