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SUPPORT FORUMS FOR ZKITS >> ZKIT 1 Support forum >> Switching to mono and preamp open questions
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Message started by holg on 09/16/23 at 12:11:44

Title: Switching to mono and preamp open questions
Post by holg on 09/16/23 at 12:11:44

Okay, so now that I've finished my ZKIT1 build and am really happy with it, I start missing the tinkering and building I did each night and am considering to build another one to be used together with the one I built.

There are just a few questions that popped up. Some or all of these questions appear like they should be obvious, but I can't seem to be able to wrap my head around it.

1) When bridging two units into mono, do I have to adjust the volume of both channels individually each time I change the volume?

2) It seems many people use a(nd additional) preamp with the ZKIT1, which surprised me since It seems to work just fine with direct connections from my phono pre and signal straight from my CD player. My understanding from reading posts on this forum ist that a preamp like the CSP3 makes the sound more dynamic and even better. Or did I misunderstand something here?
I can adjust output gain stage of my phono preamp (Schiit Mani) from 30db to 59db, and 30db definitely sounds best with the ZKIT1. The higher ones start to distort. Isn't this the same like having a higher input signal into the ZKIT, like what an additonal preamp would do (I guess?).

3) The way I understood it preamps bring a signal to line level, but aren't the signals from my CD player and from my phono preamp already at line level? Consequently does this mean that feeding the ZKIT1 with a signal higher than line level makes it sound better?

You see, I am a little confused down here and would really really appreciate a few helpful pointers to draw me out of this rabbit hole. My own research on the unterwegs and forums just seems to drag me down deeper and deeper and leaves me even more confused.

Title: Re: Switching to mono and preamp open questions
Post by jagrifen on 09/26/23 at 22:30:21

Please see below for my 2 cents:

1) Yes. Unless you use a preamp.

2) Preamplifiers are typically used to make it easier to switch between multiple sources connected to an AV system. They can also be used as the central volume control in an AV system. If a preamp is used with the ZKIT 1, the potentiometer in the ZKIT 1 can be omitted.

Preamplifiers are also used by some to "color" the sound of an AV system. This is especially true with preamplifiers that include tubes.

Preamplifiers also act as buffers in an audio system and help with impedance matching between sources and destinations. This is useful when you have a source that may need to be received by multiple destinations.

3) Preamplifiers typically operate at unity gain and therefore do not boost the audio signal level at all. The exception to this would be the phono input on a preamplifier.

I hope this helps.

Title: Re: Switching to mono and preamp open questions
Post by holg on 10/02/23 at 08:38:19

jagrifen, thank you for your reply – definitely helped to solidify my understanding of preamps in general.

Now I'm still trying to wrap my head around what a ZSTAGE or CSP3+ might add to a ZKIT. Distilling some info from this other thread on the forum https://www.decware.com/cgi-bin/yabb22/YaBB.pl?num=1519825269/0 …
… but need a bit more time to think about how this applies to what I want/need/expect in my case.

Regarding the pot in my ZKIT, it works really badly, as in the tiniest turn makes the volume jump from nothing to almost max with either my phono preamp or directly from my CD player. Wonder if it's like this for other people, too.

Title: Re: Switching to mono and preamp open questions
Post by jagrifen on 10/03/23 at 23:02:12

It sounds like the pot is likely wired up incorrectly. Can you please share model information of the pot you have used and some photos of how it is connected?

Title: Re: Switching to mono and preamp open questions
Post by Core32 on 10/04/23 at 00:22:01

Or it could the wrong value. (Probably way too large in total resistance.)
But in either case giving the part number should clear that up.

Title: Re: Switching to mono and preamp open questions
Post by holg on 10/04/23 at 07:49:20

jagrifen, Core32:

I have this potentiometer, 100kOhm version: https://www.hificollective.co.uk/potentiometer/alps-blue-beauty.html

I used the two middle pins for input, bridged the two ground pins and ran a wire to ground, and signal goes from the two outside pins to the tube. Attached is a photo (orange cable is signal coming from input selector – it's shielded all the way through to ground).

Title: Re: Switching to mono and preamp open questions
Post by Gilf on 10/04/23 at 10:55:07

With the knob facing you and pins pointed up: Center pins go to tube. Right pins go to ground. Left pins go to input. Be careful soldering, pots are among the most sensitive to overheating. :)

Title: Re: Switching to mono and preamp open questions
Post by holg on 10/04/23 at 13:57:07

Quote:

With the knob facing you and pins pointed up: Center pins go to tube. Right pins go to ground. Left pins go to input. Be careful soldering, pots are among the most sensitive to overheating.

Dang! Yeah this must be it! I thought and measured that the pot works both ways but stupidly haven’t considered that the log slope only works one way… thanks for clearing that up for me.

Seems like resoldering it is… which I’m dreading because putting the pot in there was quite the puzzle work and I don’t want to destroy it all…

Title: Re: Switching to mono and preamp open questions
Post by holg on 10/05/23 at 08:21:09

Update: It was quite the operation, but this fixed it! Thanks again!