Forums https://www.decware.com/cgi-bin/yabb22/YaBB.pl SUPPORT FORUMS FOR ZKITS >> ZKIT 4 Support forum >> How to use Zkit 4 as buffer stage or low gain pre? https://www.decware.com/cgi-bin/yabb22/YaBB.pl?num=1270813620 Message started by Hajj on 04/09/10 at 12:47:00

Title: How to use Zkit 4 as buffer stage or low gain pre? Post by Hajj on 04/09/10 at 12:47:00 I've just bought a Zkit 4 along with a Zkit 5 w/tube regulated supply. The idea is to use it as a tube buffer stage or low gain pre for my SE34-I. My setup will be as follows: Dedicated PC running foobar2000 with Asio plug-in ==>  MusicStreamer II USB DAC ==> Zkit4 ==> Octocoupler passive preamp ==> SE34-I ==> Audio Nirvana Super 12 cast frame full range drivers in a BR enclosure (might shift to ML-TQWT enclosure later on)... The USB DAC has a 2.25V RMS output voltage, and in its standard configuration (12AU7 tube), the Zkit 4 will output  5 V with 2 volts at input.  Since i don't have the expertise to bypass the DAC's amp stage (nor do I know if that's even possible) there is no real need to run the Zkit 4 as a high gain active preamp, but rather as tube buffer stage after the DAC. At least that's what my limited knowledge tells me. Please do not hesitate to bring corrections to that statement, I'd be more than happy to learn  :) On the Zkit 4's page it is mentioned that the heater voltage should be dropped to from 12.6 to 6.3 V in order to run 6922 or 6DJ8 tubes... What would be the expected gain in that case? What modifications would I need to do to drop the heater voltage to 6.3 V ? Waiting for your replies... Regards Nick P.S: Background info: I am a newbie to the tube amp world (as this post will most probably show to the tube veterans in here), but I know my way around electronics, having built more than my fair share of electronics kits in the past among which a DIY car ECU...

Title: Re: How to use Zkit 4 as buffer stage or low gain pre? Post by Hotsauce on 04/09/10 at 18:42:59 Wouldn't you want to run the buffer after the LDR, because of impedance mismatch to the amp? Try it both ways.  You might end up with one before, and one after. John C.

Title: Re: How to use Zkit 4 as buffer stage or low gain pre? Post by Hajj on 04/10/10 at 08:21:48 I was worried about the impedance mismatch issue, but I know that the LDR's impedance can be tuned to match the amp... On the other hand, the more I think about it, the more it makes sense to have the LDR between the DAC and the Zkit 4. thanks for the tip. What about dropping the heater voltage to run different tube flavors?

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