Review and Measurements of Schiit Saga Tube Pre-amp

[amirm]

Is there a for sale section to ASR?

Yes: https://www.audiosciencereview.com/forum/index.php?forums/audio-equipment-for-sale.29/

 

[michman66]

Yes: https://www.audiosciencereview.com/forum/index.php?forums/audio-equipment-for-sale.29/

THANK YOU! I AM so glad I found your site! Very professional and very helpful!

 

[Azookey]

Can someone help me understand why the tube stage (or just active stage) of the Saga attenuates the low end? I thought that buffer was meant to help it with amplifiers with lower input impedance? From what I see here, it's worse than the passive stage?

Also, Schiit used to sell Lisst solid state "tubes" making the saga a solid state preamp... how would those Lisst devices effect these kind of measurements.

Thanks

 

[amirm]

Can someone help me understand why the tube stage (or just active stage) of the Saga attenuates the low end?

It is capacitor coupled which results in a high-pass filter.

 

[Azookey]

It is capacitor coupled which results in a high-pass filter.

Is this common on all pre amp buffers or just how the saga has been implemented?

Is the passive stage better if the source feeding it has a better output stage? In that case the saga actually hurting the signal?

 

[amirm]

They could use a transformer or capacitor. They opted for the latter.

As to your second question, changing the gain will change the impedance of the passive pre-amp. So depending on what is connecting to it, there may be some impact on frequency response.

What is your application for this device? If it is just to attenuate the output of a DAC, you are much better off getting a DAC with volume control.

 

[Azookey]

They could use a transformer or capacitor. They opted for the latter.

As to your second question, changing the gain will change the impedance of the passive pre-amp. So depending on what is connecting to it, there may be some impact on frequency response.

What is your application for this device? If it is just to attenuate the output of a DAC, you are much better off getting a DAC with volume control.

Chromecast audio > schiit modi > saga > diy pass amp camp amps.

Those amps were a fun project, I don’t even want to think about how they measure. In any case they have 10k ohm input impedance which I read is low. Wondering if the saga is a wrong match for those.

I’ve also considered using a magni 3 as a preamp (has gain but don’t know if that makes any difference) or perhaps straight from the modi and use the digital volume on the chromecast.

Thoughts?

 

[TimW]

Chromecast audio > schiit modi > saga > diy pass amp camp amps.

Those amps were a fun project, I don’t even want to think about how they measure. In any case they have 10k ohm input impedance which I read is low. Wondering if the saga is a wrong match for those.

I’ve also considered using a magni 3 as a preamp (has gain but don’t know if that makes any difference) or perhaps straight from the modi and use the digital volume on the chromecast.

Thoughts?

With your amps having a 10K ohm input impedance you wouldn't want to use the Schiit Saga. As Amir wrote in the review, the Saga will cause attenuation of the bass frequencies when used with amps having an input impedance of less than 30K ohm.

I've read that the digital volume control of the CCA is 24 bit so using it shouldn't cause much degradation of sound quality.

 

[eigentone]

It would appear the new Saga S, with a solid state buffer, is DC coupled...from the Schiit description page:

It’s Your Choice: Passive or Active
Go ahead. Run Saga S in passive mode for a convenient remote-controlled passive preamp that’s ideal for many systems. If you need to drive long cables, switch it to the discrete, DC-coupled JFET buffer mode.

That sounds like the one for me.

https://www.schiit.com/products/saga-s

 

[Trdat]

They could use a transformer or capacitor. They opted for the latter.

As to your second question, changing the gain will change the impedance of the passive pre-amp. So depending on what is connecting to it, there may be some impact on frequency response.

What is your application for this device? If it is just to attenuate the output of a DAC, you are much better off getting a DAC with volume control.

On the off chance you have opted for set up which involves more than one DAC, say connected to a minidsp UDIO8 what would be the best way to simultaneously control the volume of each frequency range? Preferably with a remote...

 

[Puska]

This is a review and detailed measurements of the Schiit Saga passive/tube pre-amplifier. It is on kind loan from a member who has waiting literally months for his review! The Saga costs USD $349 from Schiit direct with stock tube plus shipping. The tube supplied with this unit was the Russian 68HC which is their clone of 6N8S (dural triode).

The industrial design is typical of Schiit product but as usual, with a different switch mechanism and looks:

View attachment 21119​

For reasons too embarrassing to explain, I had to open the unit and there, I noticed the analog volume control (which gets converted to digital), had a nice notch on it. I was happy they were using such as that would avoid the volume control becoming loose, only to realize the set screw goes on the round part of the shaft, not flat!

Anyway, back to the switches, the are microprocessor controlled and feel nice. Click the input one on the left and you rotate between five different RCA inputs. The switch on the right decides whether the Saga is a simple pass-through with volume control, or through an active hybrid tube+solid state output stage pre-amplifier. The gain in both cases is zero meaning whatever voltage you put in, is what you get out.

The volume control is a stepped attenuator using a handful of relays and resistors. Similar set of relays are used to select the right input.

Let's get into measurements and see how each mode performs.

Measurements
This being a tube amplifier, I thought I measure I measure its performance in active mode as it powered on to see how it changes:
View attachment 21120

As you see, performance is very stable. There is a very slight improvement in one channel up to about a minute but after that, there is no difference even at this magnification. This is a good thing as you don't want to age the tubes any more than you have to.

I am usually full of complaints about myths audiophiles believe it. In this case, the above busted one of my own myths that tube products require significant warm up to get to stable performance. @SIY had told me otherwise but of course, I did not listen.

With that out of the way, let's look at our usual dashboard. To really judge the performance of the Schiit Saga in passive mode, I thought I show the native performance of the Audio Precision APx555 by itself before routing the output through the Saga:

View attachment 21121

We see the tiniest amount of distortion at 2 kHz (level at -150 dB) and mains noise (level at -145 dB). There is some noise around our main signal skirt. I can get rid of that by using the digital (DAC) mode of the APx555 generator but then distortion increases. Anyway, we have a SINAD of 122 dB at this 2 volt output.

Routing the signal through Schiit Saga at max volume in passive mode we get:

View attachment 21122

There is some mains leakage that may be due to ground loop or leakage of the power supply for the active stage in Saga. Either way, this is exemplary performance with just 2 to 3 dB of loss compared to APx555.

I was holding on to my chair expect massive drop in performance when I switched on the tube:

View attachment 21123

Wow, this is very respectable! I have measured Schiit DACs with far lower performance. The offending distortion is the second harmonic at nearly -98 dB which sets the SINAD/THD+N. There are also power supply related spikes but they are at -108 dB and lower so don't come into play.

Overall, this is one good showing so far!

Let's measure frequency response at max volume:
View attachment 21124

The pass-through mode (in blue) is ruler flat, reflecting the superlative performance of the APx555.

I ran the active stage two ways: 1) with standard 100k Ohm input impedance of the analyzer (green) and 2) 600 Ohm load of the analyzer. We see that there is some droop with 100k Ohm load starting at 50 Hz and increasing to 2 dB at 10 Hz. This indicates a capacitor output stage which would naturally have increasingly higher impedance as frequencies decrease. Switching to 600 Ohm load emphasizes this and magnifies the problem substantially and artificially, giving us 16 dB of droop by 20 Hz.

The 600 Ohm impedance is essentially the inverted shape of our output impedance curve but let's run the full measurement to get the specific values:

View attachment 21125

Looking all the way to the right, the minimum impedance is 183 ohm. At the lower end of 20 Hz, impedance climbs to 3,130 ohm. Using the typical 10:1 rule, your power amplifier input impedance should be at least 30k Ohm to avoid frequency dependent/EQ changes. Put more simply, if you use lower input impedance power amplifier after Saga in active mode, your low frequencies below 500 Hz or so will attenuate. This may accentuate the rest of the spectrum you may like, or not.

The passive mode has its own issues here. Until now on purpose I have kept the volume at max as to keep the attenuator resistors out of the way. The moment you turn down the volume, you will be putting varying amount of resistance in the output path and thereby, increase impedance. Here is the output impedance curve in passive mode with volume around 20%:

View attachment 21126

The cursor is at 144 Hz showing an impedance of 2,760 ohm. This is in contrast to just 21 ohm impedance at max volume reflecting the 20 ohm output impedance of the APx555 analyzer.

Plotting a few points on the volume control gets us this:
View attachment 21127

So essentially, any volume level less than 50% is going to increase the impedance substantially. Fortunately the attenuation is not frequency dependent so the impact is not there as there is with tube stage. However if the input impedance of the power amp changes with frequency and is less than 30k Ohm, then turning down the volume may change the frequency response. Perfection in distortion and noise has this price.

Conclusions
I must say, I developed a fondness for this little pre-amp. I have no idea why as I would never use it myself. It just seems like a neat combination of features in a pretty low cost package. If you are looking for its features and are mindful of drawbacks with respect to its varying output impedance, then I don't see a reason to not get and play with it. You could use it as a nicely implemented audio switcher for example with the volume control for fine tuning of max level.

So, good job Schiit.

------------
As always, questions, comments, recommendations, etc. are welcome.

They say you should save money for a rainy day. It rains for about 6 months here so I need plenty of money!!! Please consider donating funds using:
Patreon: https://www.patreon.com/audiosciencereview), or
upgrading your membership here though Paypal (https://audiosciencereview.com/foru...eview-and-measurements.2164/page-3#post-59054).

Is it possible to use Saga+ as a headphone amplifier?

 

[nhatlam96]

Why would anyone activate the tube on this device? The difference between tube and no tube should be inaudible.

 

[chad2]

have you ever considered measuring the VALI?

 

[michman66]

I had the first version and I wound up selling it as I could not get the volume I like ( sometimes) loud enough. My Amp is a Linn LK 140 with 22k input impedance. Seeing this review helps me understand why. My Dac has a 2v output and low output impedance ( D50s)

 

[Cougar]

I have the Schiit Saga + and its way better built than the one Amir did the review on. The rev I have has a motorized volume pot and is a way better components passive/active tube buffer than original.

I would be really interested how the Saga + measures.

 

[MattJ]

I have a new Saga S (and a Vidar) and would be really interested to see how it measures. I think it sounds great, absolutely dead quiet, even with my ear right next to the tweeter and max volume. I think I prefer the active stage, but a slight volume dip for the passive stage probably contributes to that. Very clean in either setting. For $299, it is right up there with equipment many times its price.

 

[bajwe]

Hi, can any users tell me if the Saga remembers the volume level for each input? The manual is silent on that so I suspect it doesn't.

 

[Jimster480]

Hi, can any users tell me if the Saga remembers the volume level for each input? The manual is silent on that so I suspect it doesn't.

A good rule of thumb is that if they do not advertise it that the feature does not exist.

 

[Cougar]

Hi, can any users tell me if the Saga remembers the volume level for each input? The manual is silent on that so I suspect it doesn't.

No It doesn't for each input but will remember the level if you don't lower it before you turn it off.

 

[Cougar]

Just some info for those that have the Saga + and need a little more output. I bought an ART RCA to XLR converter and it works really well with the Saga +. I have way more output now. I just run the RCA's from the Saga + to the unbalance input of the ART and use the XLR out from the ART to my Crown XLS 1502 XLR inputs. I set the inputs sensitivity to 1.4V on the Crown and adjust the levels for the input on the ART and there you have it! More output and dead quiet now that it's in Balanced mode. I can't even go past the halfway mark on the Saga+ enough volume and to me sounds a lot better now which it sounds great already. Hope this helps.