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SUPPORT FORUMS FOR ZKITS >> ZKIT 5 Support forum >> ZKIT-5 as a buffer?
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Message started by Steve Deckert on 08/23/10 at 15:50:51

Title: ZKIT-5 as a buffer?
Post by Steve Deckert on 08/23/10 at 15:50:51

Quote:

Hi Steve,
I have had my Zkit 4+ Zkit 5.1 for some 6 month now.
I have been using it as some sort of tube buffer stage between my external DAC and an SS tripath amp.
Tried using it with my SE 34-I but the gain was too high.
So the question is, will swapping the 12au7 for a 6922 (by merely dropping the heater voltage to 6V) lower the gain and allow me to use it as a unity (or closer to unity) gain tube buffer?
If not, what other mods are required?
I have been reading up on the internet, and some say that 6922 tubes have lower gain than 12au7, while others say the contrary. I'm lost (although, as per the spec sheets of the tubes 12au7 mu=17, 6922 mu=33)
A gain of anywhere between 0.9 and 1.1 should do.
I've read all the related posts on the decware support forums, but since i don't want to mount a pot in the signal path, still could not find the right answer.
Thanks

The ZKIT5 is a gain stage. The 12au7 and 6922 have about the same gain so you would notice no difference should you modify the unit to accept 6922.

What you need is a buffer stage. Perhaps we'll add one to the ZKIT line since it seems you're not the first person to need one.

The solution to your problem is simple enough. Just add a 100K audio taper pot to the output of the ZKIT5 so that you can adjust the gain from zero to max. Unity gain would be somewhere in the middle. This is how we do our ZCD player, which uses the ZKIT5 as it's output stage.

- Steve

Title: Re: ZKIT-5 as a buffer?
Post by Steve Deckert on 08/23/10 at 15:52:43

If you really don't want to use a pot, consider a stepped attenuator or install a pot, find the ideal setting, measure the pot and replace it with a pair of fixed resistors.

Steve