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EQUIPMENT FORUMS >> ZROCK2 >> Passive Pre + Zrock2
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Message started by Puggy on 03/23/22 at 00:24:32

Title: Passive Pre + Zrock2
Post by Puggy on 03/23/22 at 00:24:32

I’m interested in building a high quality passive-type pre using the Zrock and another device to control volume and switch between 2 sources.

I currently have a Zrock with anniversary mods and zen switch box on order, but they are not expected to arrive for a very long time with the current wait.

Would the best option for a passive pre be to add a stepped attenuator to the ZSB, or use a another passive pre (Luminous Audio Axiom, TVC device, etc.) to control volume in combo with the Zrock?

I used to have a CSP3, which was a fantastic pre, but I slightly prefer the transparency of going directly into the amp from the phono stage. However, I’m adding the Zrock to give the signal the bottom end and weight, and my amp only has one input.

My current setup is Turntable -> ZP3 -> 300b SET power amp OR push/pull KT88, both with built-in volume controls. Im switching cables when I listen to the DAC. I would like to have a “purist” style pre to open the possibilities for amp pairings that don’t have a volume control, and would be higher quality than the volume pot built into a power amp.

Open to any opinions or advice, thanks!

Title: Re: Passive Pre + Zrock2
Post by GroovySauce on 03/23/22 at 13:30:27

I'm a fan of autoformers as a volume control. Dave Slagle https://intactaudio.com/atten.html makes the best autoformers for audio. If you want a nicely completed unit, look at EMIA. I have the remote autoformer and love it! https://myemia.com/Products.html .

Title: Re: Passive Pre + Zrock2
Post by Puggy on 03/23/22 at 15:30:06

Thanks so much! I’ll check these out. I just learned about using auto formers as volume controls. Seems like these are generally preferred over typical volume pot or stepped attenuator. Obviously the more expensive option. Do you run your Torii fully open and fully use the EMiA for volume control?

Are there any impedance concerns with using one of these in front of a Zrock? My amp is 50k input impedance, which should work fine coming out of the Zrock.

Title: Re: Passive Pre + Zrock2
Post by GroovySauce on 03/23/22 at 16:19:22

I'm glad you mentioned impedance matching.

50K ohm input should be fine. If the amp was 20K I would suggest emailing Dave about any issues. The Zrock2 is 47k input impedance, so all good on that point.

I had my Torii made with no attenuator, therefore my amp is always "wide open". My only volume control is the EMIA unit.

Title: Re: Passive Pre + Zrock2
Post by Puggy on 03/23/22 at 23:54:42

Great, this is all very helpful.

Any experience with AVCs vs TVCs (transformer volume control)? I’ve seen many more TVCs in my search.

Do you run the Zrock directly after the ZP3 and before the EMIA? I’d like to run both my digital and analog sources through the Zrock, so ideally after the TVC/AVC.

Title: Re: Passive Pre + Zrock2
Post by GroovySauce on 03/24/22 at 00:43:12

I don't even know what the differences are between a TVC and AVC. ;D I've also seen them used interchangeably. So maybe someone else can educate us.

I've run both ways. Both sound glorious.

ZP3/DAC->EMIA-ZR2->Torii
ZP3/DAC->ZR2->EMIA-Torii

The Zrock2 has 47K input impedance so it's a nice load for either source to drive. The Schitt has a 75 Ohm output so in theory it should do great. The ZP3 is < 1k Ohms and drives the EMIA into the Zrock2 well.

Title: Re: Passive Pre + Zrock2
Post by Puggy on 03/24/22 at 18:24:43

Very cool. Sounds like both sources will work great. I believe AVCs and TVCs are very similar if not the same thing. Definitely the same overall concept.

The one that keeps coming up in my search is the Prometheus TVC. Not at the quality of the EMIA, but seems a few steps beyond a standard volume pot or attenuator.

My Zrock is still many, many months away from arriving so I’ll keep looking around. Thanks again!