This is a review and detailed measurements of the JBL Synthesis SDR-35 Audio/Video Receiver with 16 channels of processing with class G amplification and support for Dirac Room EQ. It is on kind loan from a member and costs US $8,250.
The unit looks elegant and user interface is simple to operate using the large LCD on the left. Back panel shows the usual connections including too many analog inputs:
This unit was upgraded with the latest HDMI board and certified to be working correctly.
There are three fans but I don't think any of them came on. Internal amplifier fins are step above "spring steel" of cheap AVRs with extruded but thin aluminum. Class G operation of amplifiers keeps the unit from getting overly hot.
There is a ton to measure here, taking me almost two days to work through them. A quirk of the unit caused fair bit of delay. When it goes into protection -- which it goes into instead of clipping -- it will seem to not want to restart. You can power cycle it all you want and all you get a red indicator. I thought the amp was damaged only to realize that it is going to suspend mode. Hitting any key wakes it up but then you have to wait for it to boot again.
Here are the product specs:
Note: my other venture, Madrona Digital is a custom integration company that buys a lot of Harman products (parent of JBL). So feel free to read any amount of bias you like in this review.
JBL SDR-35 DAC Measurements
As soon as I started to test the DAC by capturing pre-out I realized that we have our usual problem of internal amplifier being stressed before we get to 2 volts nominal. I could actually hear the transformer squealing as I kept cranking up the volume (with no speakers connected). Going with it anyway, we get this not so good SINAD:
The distortion is caused by clipping but the sidebands around the main tone are not (see jitter test later). You can see this by switching inputs to toslink:
The jitter pattern around our main tone clearly changes. This naturally puts a dim light on the performance of other AV products using the same 2 volt output (or 4 volt for balanced):
This is caused because the internal amplifier runs at very high gain relative to the output of the DAC:
Peak performance is at just 0.8 volt. An external amplifier that produces more power than the internal one will surely require more than this for maximum output. Even that aside, the internal amps are going crazy even though you are using an external amplifier. An amp shut down option needs to be implemented to fix this problem.
Might as well get a second serious problem out of the way which is the muting of input below 90 dBFS over Toslink:
We have seen this before. Either these companies are sharing the same platform or there is some kind of valid reason for this. Either way, it needs to be clearly documented and defeatable.
Our SNR is not bad for an AV product but no competition for a proper home/desktop DAC:
IMD vs level shows the saturation problem we saw before:
I noted jitter is bad and you can see it well here:
DAC reconstruction filter is both slow and doesn't attenuate much:
This guarantees poor performance in higher frequencies in our wideband THD+N vs frequency:
These are simple things that should be fixed but are not.
JBL SDR-35 Amplifier Measurements
Performance of AV products usually changes sharply depending on what input you use. Let's start with the worst case which is analog input:
As you see, if you don't select Direct mode which bypasses digital processing, the input gets digitized at 44.1 kHz (or maybe 48 kHz). For a statement AVR, I expect to see double this sample rate. This is doubly so if it means internal DSP processing is as low.
Here is our dashboard using CD input in Direct mode:
This is good but you don't get any processing. If you go to normal analog input, you get this large drop:
Why use such low quality conversion to digital? Surely we can better than 12 bits here?
Going with CD direct performance, overall ranking is excellent for the class:
Since many of you use digital input, here is that performance:
So you gain a bit more still confirming that the internal DAC is transparent enough for the amp (as could be predicted from its SINAD).
Here is our dynamic range at 5 watts and full power:
Again, for this type of money I like to see much better performance. Best case you are still not getting to 105 dB THX specification.
Crosstalk for analog input is not bad:
Let's measure power into 4 ohm using both analog input methods:
We get about 200 watts of power which is about what the spec says. I could not run my max and peak power as the unit would constantly shut down before I could get to 1% THD. This means you have no headroom anyway since the aggressive protection circuit kicks in.
Let's measure it with 8 ohm:
Overall noise and distortion is a bit above average for class especially before it clips.
Switching to digital input, we get the following:
I had to be careful in running my frequency power sweeps to avoid the unit shutting down. Even so, the 20 Hz tone still caused it to go into protection:
Power output at that frequency is nearly half of max power. If you are crossing over the amps to a sub at higher frequency this should not be a major issue. Otherwise, I expect to see better performance. Fortunately linearity is excellent with almost no frequency dependence. There is a notch in performance which I assume is in the transition region of amplifier switching rail voltages (the class G scheme).
Conclusions
While you are being charged large premium for this AVR, SDR-35 suffers from many of the problems we have seen in other AVRs. Its DAC saturates very early making it pretty useless to pair with external amplifiers. The bug with muting below 15 bits is not acceptable. Neither is poor reconstruction filter. This is type of performance I expect in a $20 no-name DAC.
Amplifier raw performance is competitive with better AVRs. However its protection circuit is quite aggressive and method of recovery rather annoying. This is impacts someone like me more than a user though.
The main thing you are getting here over a cheaper alternative is perhaps more channels being processed. Other than that, I fail to see what is premium about it with respect to performance.
I can't recommend the JBL SDR-35. It is just way too much money for this level of delivered performance.
-----------
As always, questions, comments, recommendations, etc. are welcome.
Any donations are much appreciated using: https://www.audiosciencereview.com/forum/index.php?threads/how-to-support-audio-science-review.8150/
The unit looks elegant and user interface is simple to operate using the large LCD on the left. Back panel shows the usual connections including too many analog inputs:
This unit was upgraded with the latest HDMI board and certified to be working correctly.
There are three fans but I don't think any of them came on. Internal amplifier fins are step above "spring steel" of cheap AVRs with extruded but thin aluminum. Class G operation of amplifiers keeps the unit from getting overly hot.
There is a ton to measure here, taking me almost two days to work through them. A quirk of the unit caused fair bit of delay. When it goes into protection -- which it goes into instead of clipping -- it will seem to not want to restart. You can power cycle it all you want and all you get a red indicator. I thought the amp was damaged only to realize that it is going to suspend mode. Hitting any key wakes it up but then you have to wait for it to boot again.
Here are the product specs:
Note: my other venture, Madrona Digital is a custom integration company that buys a lot of Harman products (parent of JBL). So feel free to read any amount of bias you like in this review.
JBL SDR-35 DAC Measurements
As soon as I started to test the DAC by capturing pre-out I realized that we have our usual problem of internal amplifier being stressed before we get to 2 volts nominal. I could actually hear the transformer squealing as I kept cranking up the volume (with no speakers connected). Going with it anyway, we get this not so good SINAD:
The distortion is caused by clipping but the sidebands around the main tone are not (see jitter test later). You can see this by switching inputs to toslink:
The jitter pattern around our main tone clearly changes. This naturally puts a dim light on the performance of other AV products using the same 2 volt output (or 4 volt for balanced):
This is caused because the internal amplifier runs at very high gain relative to the output of the DAC:
Peak performance is at just 0.8 volt. An external amplifier that produces more power than the internal one will surely require more than this for maximum output. Even that aside, the internal amps are going crazy even though you are using an external amplifier. An amp shut down option needs to be implemented to fix this problem.
Might as well get a second serious problem out of the way which is the muting of input below 90 dBFS over Toslink:
We have seen this before. Either these companies are sharing the same platform or there is some kind of valid reason for this. Either way, it needs to be clearly documented and defeatable.
Our SNR is not bad for an AV product but no competition for a proper home/desktop DAC:
IMD vs level shows the saturation problem we saw before:
I noted jitter is bad and you can see it well here:
DAC reconstruction filter is both slow and doesn't attenuate much:
This guarantees poor performance in higher frequencies in our wideband THD+N vs frequency:
These are simple things that should be fixed but are not.
JBL SDR-35 Amplifier Measurements
Performance of AV products usually changes sharply depending on what input you use. Let's start with the worst case which is analog input:
As you see, if you don't select Direct mode which bypasses digital processing, the input gets digitized at 44.1 kHz (or maybe 48 kHz). For a statement AVR, I expect to see double this sample rate. This is doubly so if it means internal DSP processing is as low.
Here is our dashboard using CD input in Direct mode:
This is good but you don't get any processing. If you go to normal analog input, you get this large drop:
Why use such low quality conversion to digital? Surely we can better than 12 bits here?
Going with CD direct performance, overall ranking is excellent for the class:
Since many of you use digital input, here is that performance:
So you gain a bit more still confirming that the internal DAC is transparent enough for the amp (as could be predicted from its SINAD).
Here is our dynamic range at 5 watts and full power:
Again, for this type of money I like to see much better performance. Best case you are still not getting to 105 dB THX specification.
Crosstalk for analog input is not bad:
Let's measure power into 4 ohm using both analog input methods:
We get about 200 watts of power which is about what the spec says. I could not run my max and peak power as the unit would constantly shut down before I could get to 1% THD. This means you have no headroom anyway since the aggressive protection circuit kicks in.
Let's measure it with 8 ohm:
Overall noise and distortion is a bit above average for class especially before it clips.
Switching to digital input, we get the following:
I had to be careful in running my frequency power sweeps to avoid the unit shutting down. Even so, the 20 Hz tone still caused it to go into protection:
Power output at that frequency is nearly half of max power. If you are crossing over the amps to a sub at higher frequency this should not be a major issue. Otherwise, I expect to see better performance. Fortunately linearity is excellent with almost no frequency dependence. There is a notch in performance which I assume is in the transition region of amplifier switching rail voltages (the class G scheme).
Conclusions
While you are being charged large premium for this AVR, SDR-35 suffers from many of the problems we have seen in other AVRs. Its DAC saturates very early making it pretty useless to pair with external amplifiers. The bug with muting below 15 bits is not acceptable. Neither is poor reconstruction filter. This is type of performance I expect in a $20 no-name DAC.
Amplifier raw performance is competitive with better AVRs. However its protection circuit is quite aggressive and method of recovery rather annoying. This is impacts someone like me more than a user though.
The main thing you are getting here over a cheaper alternative is perhaps more channels being processed. Other than that, I fail to see what is premium about it with respect to performance.
I can't recommend the JBL SDR-35. It is just way too much money for this level of delivered performance.
-----------
As always, questions, comments, recommendations, etc. are welcome.
Any donations are much appreciated using: https://www.audiosciencereview.com/forum/index.php?threads/how-to-support-audio-science-review.8150/