Decware ZSLA buffer -- worth cloning?

[ssmith]

Hi everyone,
I'm thinking about a first real tube project -- and had for a while been looking at a single ended triode, unity gain tube buffer/linestage by Decware. It seems to be discontinued now, although the schematic (pdf) is still available. It looks fairly simple too with a very low parts count, -- perhaps decent project for a tubes newcomer, and I already have some of the parts in the box.



More archived info here, and a review is here.

Was just wondering if anyone could cast an eye on the details, and whether there were any thoughts on whether this would be a worthwhile project? I don't need a preamp with gain, although a tube buffer may be what is called for for the discreet output of my dac and in the middle of a solid state system.

thanks in advance!

[planet10]

Basically a cathode follower... it will present a high impedance input and a low impedance output. Whether it makes things sounds better depends on how much you gain from the impedance buffering vrs what is lost from the CF (miss piggy as Allen Wirght says)

CCS on the bottom of the CF will make a BIG improvement. (or a big B- for a long tail)

dave

[rdf]

Originally posted by planet10
Basically a cathode follower...

Even with the jiggery-pokery happening on the output plates? Into the typical 47kohm amplifier input impedance the tube's AC load appears split something like 2:3 plate:cathode.

[planet10]

Oops... the drawing is done a bit strangely,,, the 15k in the anode wouldn't be there in a true CF. The C8 PS cap may also be small enuff to affect FR too?

dave

[ssmith]

Originally posted by planet10
Whether it makes things sounds better depends on how much you gain from the impedance buffering vrs what is lost from the CF (miss piggy as Allen Wirght says)

Thx Dave - seems different though to how Decware marketed it, as a preamp that makes things sound better -- I assume by smoothing harsh sources by providing some tube 'warmth' (hate to use that term though) to a SS system, as well as providing better drive for long ICs...

[diegot]

Someone can explain how this topology affect the bias?

Thanks

[ssmith]

Well, given I have some of the parts and the rest would be cheap, I think I'll go ahead and give it go anyway -- then perhaps think of mods like a CCS, which at this stage I'm googling and working out how to implement in the schematic. The upshot is that it seems to be the simplest schematic I've found...
Any other opinions would be welcome though.