SUPPORT FORUMS FOR ZKITS >> ZKIT 1 Support forum >> ZKIT2 -> ZKIT1 build and the next one.

Message started by solder bob on 10/17/20 at 16:40:14

Title: ZKIT2 -> ZKIT1 build and the next one.
Post by solder bob on 10/17/20 at 16:40:14

Was looking for a lock.down project earlier this year... So I built two of these, based on ZKIT2 board. Identical, with the idea to have 2 amps I could bridge etc.... The box in back is a Z-stage I built using the online schematic, and is a simple switch box/gain control.

I built the ZKIT2 as spec'd, chased a few grounding issues, and got obsessed over the small hum I could hear about 6in from cone on my RP-600m. 1.1mv

As many on the forums mentioned, I threw capacitors at the issue. Using UF diodes, and smoothing at 47k and first filter at 94 k. This quieted things down substantially, but x2 was stressing transformer with the 2 kits as mono blocks...

Couldn't leave things alone, so these 'morphed' into a sort of anniversary ZKIT1. I converted to a single power supply and modified parts to match ZKIT1 anniversary version, with. the 47/94 filter stage. And boom.... started with 6922/EL84M, but I found 6N1P/6P15V to have best sound. Only issue is I need extra input tubes.... :)

I am actually using one of these in my kitchen system with an old set of BW LM1 and a sub, at surprising levels, and perhaps most importantly, my better half has actually noted the sound quality improvement.

So begins the next phase of my journey on a p2p version of the SE84 with tube rectification, meters, real center taps etc... This amp, even on a prototype layout is outstanding. That said, I had the same issue with the ~1.1mv of hum. Not hearable from my listening seat with high efficiency speakers, only at about 6in from cone or less. This is not a complaint, rather just an observation. Some of my other other tube stuff (bob latino kits) is dead quiet, and I enjoy... but the little zen circuit is magic.

I appreciate the balancing act of PS responsiveness linked to sound quality.  So now I need to decide if I should quiet things down with a choke as first filter stage and a big ass filter cap. Ive been doing some a/b and I think 'as designed' is defintely faster. Now Im playing around with bypassing all the caps to speed things up. Not sure where I will land on the final power supply build, but I just ordered a nice brushed stainless steel plate to mount everything so marching on!

ForZKIT 2 the chassis,I used a custom front panel express chassis. It was a little expensive but nice and solid. For the panel on my P2P build I went another direction, check out this company called sendcutsend. I designed the panel in sketchup. Uploaded and with all the laser cut holes etc. it ended up being $50. They can laser cut all sorts of metals (titanium or copper plate anyone?), and are very quick.

Here is the ZKIT2 / stage chassis. Was playing with knobs when picture was taken...

Very grateful to Steve for putting his designs out there, and for this incredible piece of audio simplicity.

Here to learn, share and connect with this great community after lurking for 6 months...

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