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Review and Measurements of Schiit Sys Passive Pre-amp/Switcher

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I am a happy user of the now discontinued Emotiva Control Freak volume control (rca version) in my desktop system. Desktop PC as source, into an ODAC usb DAC, into the Control Freak, into a pair of inline atenuators into a Quad 405-2 power amplifier into a pair of Harbeth P3ESRs. I added the inline attenuators because the ODAC's output voltage of 2.0V is a bit much for the Quad's 0.5V input sensitivity. Without attenuators there was a real risk of accidental damage to the speakers, and with the attenuators I also avoid potential channel imbalance at low volume settings of the Control Freak. Of course I have no way to measure, but the result sounds fine to me.

Nice. I didn't seem like the Control Freak had a remote control which is why I'm trying to mod the shiit sys with some sort of external motor. There seems to be a jump in price from 50$ for a passive attenuator without a remote to 300$ minimum with a remote. and I don't think that 250$ %/SQ improvement ratio is very good at all/worth it so i can keep my butt on the couch.
 

solderdude

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The reason why I am using a SYS is because I have a turntable coming in on one of the channels. I guess that a switcher would do as I never use the volume on the SYS, but I simply did not know which switcher to buy. At least with the Sys, Amir measured it to be transparent.

Perhaps we could have for a RCA audio switcher roundup with all the measurements etc :)

In this case the Rout of the Sys = 0 Ohm (not 5k) and the Modi is loaded with 7.1k Ohm instead of 25kOhm.

The only difference some switchers could have is crosstalk or interference with unshielded cables or wiring.
The Sys works fine as the ground is very low impedance as it is made of the entire groundplane of the PCB.
Just switches and wires could well be worse in some aspecets.
 

Jimster480

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I prob shoulda mentioned it was hooked up to a LKS DH-004, A Gustard U16 and a pair of EP 2.8's so keeping the chain as clean as possible is important.

No amp though he just makes me peddle a stationary bike reallly fast

We're using a custom built pc with a AMD 1950x 16-core CPU with HQplayer upsampling to DSD512 ( and poly-sinc-xtr-mp if you're familiar with hqplayer ) and its pretty freakin incredible.

My mom taught me the idiom pennywise pound foolish
A threadripper for playing music! WOW is all I can say!
 

la2ygoo

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The output level , when at 3:00 is -5.5dB , at 12:00 is -16dB , at 9:00 is -32dB.
Base on output level , thd+n should be like this.
Schiit Sys THD+N measurement output level.png


With sys 9:00 volume , in % way , i think : THD+N(-30dBV output) = THD+N(Ap@2dBV) + THD+N(sys@-30dBV) , 0.0025% = 0.0002% + THD+N(sys@-30dBV) , so THD+N(sys@-30dBV) = 0.0023%

If a dac is 100 times worse than Ap, when it uses sys output -30dBV, THD+N = THD+N(Ap@2dBV)*100(=0.02) + 0.0023% = 0.0223% , it become 9 times worse than Ap.
If a dac is 10 times worse than Ap, when it uses sys output -30dBV, THD+N = THD+N(Ap@2dBV)*10(=0.002) + 0.0023% = 0.0043% , it become 2 times worse than Ap.

A poor dac can use sys(or another preamp) to greatly reduce THD+N at low volume output , is it right?
 
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mshenay

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We ever do the measurements for the OL Switcher?

I'll admit after stumbling across this, I've been using my SYS to switch between 2 Tube Amps out of my RME ADI 2's single output. Granted there are no un used input or output. Everythings' hooked up to something
 

Guddu

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1589387690914.png


Hello FM,
FAQ on Schiit product page says it may not be the best choice if running long RCA cables and suggests cables around 15 inch.
Any observations or opinion on this please?
 
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EddieFreak

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View attachment 63272

Hello FM,
FAQ on Schiit product page says it may not be the best choice if running long RCA cables and suggests cables around 15 inches.
Any observations or opinions on this, please?

Being a passive device, long cable runs would be a bad thing. I would definitely stick to under a meter. The shorter the better.
 

Sal1950

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View attachment 63272

Hello FM,
FAQ on Schiit product page says it may not be the best choice if running long RCA cables and suggests cables around 15 inch.
Any observations or opinion on this please?
Actually what they're saying is 15 feet not inches. And that is good info, for a passive preamp keeping the output cables as short as possible is spot on.
 

gvl

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Even if you keep the cables short, how do you know if the input capacitance of the downstream amp?
 

Sal1950

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Even if you keep the cables short, how do you know if the input capacitance of the downstream amp?
Input impedance is the important spec, should be in the amp specs.
 

gvl

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Input impedance is the important spec, should be in the amp specs.

The impedance is, but not the capacitance typically, or are you saying you can derive one from the other across the audible frequency range? Isn't the input impedance typically measured at 1kHz only?
 
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Sal1950

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The impedance is, but not the capacitance typically, or are you saying you can derive one from the other across the audible frequency range? Isn't the input impedance typically measured at 1kHz only?
I really don't have the technical expertise to answer your questions in detail correctly. The place where capacitance becomes critical is in the interconnect, a high value possibly causing a rolloff of the high frequencies. Source impedance's need to be low and amp input impedance high to minimize the effect of cable capacitance. I'm hoping others with the background will come to my rescue here.
 

gvl

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I really don't have the technical expertise to answer your questions in detail correctly. The place where capacitance becomes critical is in the interconnect, a high value possibly causing a rolloff of the high frequencies. Source impedance's need to be low and amp input impedance high to minimize the effect of cable capacitance. I'm hoping others with the background will come to my rescue here.

Cable or amp input capacitance is all the same, they form an RC filter with the passive pre which effectively increases the source output impedance. Based on what I could find amp input impedance is typically measured at 1kHz and the HF impedance may actually be much lower than the spec causing HF droop with a passive pre in the chain, short cables or long.
 

aerochrome2

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I am planning to add a turntable to my setup and will need an rca switcher. I don't need a volume knob, but like a past poster, would be willing to pay a little extra vs. grabbing a random one off of Amazon if I can be sure it's transparent. Since the ol switcher hasn't been tested yet, is this my best bet?
 

gvl

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I am planning to add a turntable to my setup and will need an rca switcher. I don't need a volume knob, but like a past poster, would be willing to pay a little extra vs. grabbing a random one off of Amazon if I can be sure it's transparent. Since the ol switcher hasn't been tested yet, is this my best bet?

If you don't need a volume knob get one without a volume knob just to make sure it doesn't affect your setup. Emotiva SP-1 looks interesting at $199 on closeout, and it comes with a phono stage built in and a remote. Should be transparent enough, but it wasn't dissected here.
 

aerochrome2

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If you don't need a volume knob get one without a volume knob just to make sure it doesn't affect your setup. Emotiva SP-1 looks interesting at $199 on closeout, and it comes with a phono stage built in and a remote. Should be transparent enough, but it wasn't dissected here.
Yeah, the SP1 looks good (I was actually looking at it earlier today), but it would be a bit more expensive vs pairing an art dj pre ii phono pre amp with a sys (for example).

I would get support for magnetic coil though. Any other benefits?
 

gvl

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Yeah, the SP1 looks good (I was actually looking at it earlier today), but it would be a bit more expensive vs pairing an art dj pre ii phono pre amp with a sys (for example).

I would get support for magnetic coil though. Any other benefits?

Lack of pot in the path, one more input, remote for input switching, the looks. I can't think of anything else.
 
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