This guide is to help you build the DOUK KSL-M77 Preamp clone kit.

[Kanders1]

The responsibility is with you to make sure you understand the safety implication of Valve amplifiers. They can kill you!

The modification worked on my amp. If it does not work for you then I am not responsible for any damage you may incur.

If you use this information its at your own risk. It’s a guide. I did a lot of research into building this amp I suggest if you don’t like the suggestions then do your own research and your own modification.

This is a very good sounding Preamp! It’s not by any means the Kondo M77 !! Just Google the real thing and be impressed by just the images! But for around 30k it should sing you to sleep and make your breakfast! Having said that you wont be disappointed with the clone its fun to build and lends itself to modifications and upgrades.

There are some fundamental items you will need to complete this build.

A soldering iron with a flat tip and a pointed tip
Solder
A test meter
Screw drivers
Wire stripper
Heat shrink insulation
Tweezers for SMD components.

Best regards,
Karl Anderson


Building the KSL-M77 Clone from DOUK/NOBSOUND

The build is relatively straight forward, even with very little ‘electronic’ knowledge. Having said that you will need a steady hand for soldering and if the amp does not work when finished you may need a friend who does know their way around a valve or two. The reason being is that at the time of writing this document the schematic that is supplied with the board is not accurate and there are a few values and items missing from it. One thing that you will notice is that there are 9 valves in total on the board but only 7 shown on the schematic. But if you look close you will see one section does show a 1/2 therefore implying the section is copied.

The amp has a great sound! And for the cost it’s hard to better! BUT out of the box build it “Hum’s” like it don’t know the words..!! The good news is that it can be fixed. This is where you need the soldering skills.

The board can be bought in three states, just the board, built with no capacitors and finished. (There are no valves supplied with any build).

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I personally went for the finished board, mainly because its tested and one less issue for me to look into if it does not work. I then upgraded the parts I believe needed changing. The choice is yours..!

You will need a box! And it needs to be big enough to fit the amp board, a good-sized transformer and an extra power rectifying/smoothing board. There are a number of boxes out there just be mind-full that many do not have holes drilled and text on them. Drilling holes not such a big issue but screen-printing text to get the ‘Pro’ look isn’t that easy. Again the choice is yours.

I bought the ‘Kondo KSL-M7 box off E bay purely because it has the right holes and the text is correct for the amp functions. The only issue I found is that the M7 board is smaller than the M77 board and fitting the ‘on off’ and volume pot requires some thought and slight modifications. Also if you want to fit different caps later on as an upgrade the volume pot will limit the physical size of capacitors.

The chassis comes with power inlet (cheap don’t use) on/off switch (again not very nice) Two solid aluminium control knobs. All screws, An LED and a safety cap are supplied. The chassis was very well packaged and comes flat packed overall excellent quality. Very quick delivery too!

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The transformer, I purchased the DOUK 230V one meant for the board. Reasonable price plus it’s got all you need for the amp on it. Again as long as you have the right outputs you can source a transformer of your choice. (Required Outputs are 100W, 250v-0v-250v 12.6v and 6.3v)

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