Upgrading a WAD K5881 to K5881 MKII

[ZakB]

Hi All,

I currently have a WAD K5881 Mk1 amplifier that I built a while ago - 1994 I think! I have been thinking about upgrading it to a MkII version. Do any of you know what the sonic advantages of doing this are? I would be interested in hearing any opinions you might have on whether or not it is worth doing.

Many thanks in advance.

[Richard]

Hi Zak,

I can't recall many posts about this amp or the MkII version. It was all a bit pre-web I think. I know the amp myself but haven't had the 2 version side by side for a listening. Noel set out to make it sweeter and more neutral and felt he achieved that in the article. The only real downside was high sensitivity but that could be fixed easily enough with a divider on the input if needed.

I have all the info if it's that which you need. Looking back at this and later Kel34, Kit88, and many of these 5-20 clones, much of the changes between them seems focussed around the input valve. Yours uses EF86 in triode mode which is fine if you like the sound but doesn't give much option for trying different makes or near equivs so the MkII would at least allow this with any ecc83 type.

There's a lack of medium gain triodes, commonly they jump from mu 17 of ecc82 to mu 60 and 100 of ecc81 and 83 and nearly all are twin valves. Something around 30 would be good. The 6072 at 40 is great but not common or cheap.

Give it a go anyway if you feel able and we can certainly help out if you run into snags.

Rich