SPL Volume8 Review

[mdsimon2]

OK, but what if all the music I listen to is 16 bits? And what if not all my sources are digital? You can't produce dynamic range that don't exist, and while it may be true in most cases, in the end it's still all about gain structure, and the problem is that sensitivities are all over. The most transparent DAC with digital volume control in the world can still present audible hiss if the gain downstream is not adequate for the transducer you are using, in the end everything must be viewed as a system working together. Nothing against digital volume, but again, benefits and compromises.

Why is 16 bit data an issue? A 32 bit DAC (or DSP) will happily attenuate 16 bit with essentially no quantization error for the vast majority of attenuation levels. Here is a digital measurement of a 32 bit DSP with a 1 kHz 16 bit input with 35 dB of attenuation, there is no quantization error and we maintain -96 dB THD+N. The limiting issue here will be analog noise from the DAC / amplifier and not quantization error from digital volume control.

I've used DSP in all my systems since my first forays in to car audio 15+ years ago so I have no issue with digitizing analog sources and these days ADC quality is so high I am quite confident that it will be nowhere near limiting compared to the analog source.

I agree that sensible gain structure is a prerequisite and unfortunately it is something that is often ignored. However I can assure you that I have very good understanding of the residual noise requirements at the speaker terminals to avoid speaker hiss with the speakers I use and it can be achieved with relatively middling pro audio DACs and Hypex / ICEPower amplifiers, see this thread for more info -> https://www.audiosciencereview.com/...m-china-with-topping-performance.24768/page-2.

I just don't see where this device fits in a modern world with digital volume control and low noise DACs, especially at the price.

Michael

 

[mdsimon2]

Almost certainly for controlling surround sound signals going to monitors. These multichannel volume controls are almost always for people who are distrustful of digital volume attenuation since they believe it will introduce noise.

Setting up monitoring for 5?1 or 7.1 sound is expensive business unfortunately. I think you need a special version of protocols for example.

Some speaker diy people also use devices like this to control all 8 channels of an active 4 way speaker like a linkwitz lx521. You send a digital signal to a minidsp, which then outputs 8 channels of digital audio to 4 different stereo dacs. You then attenuate the dac with this device before sending to 8 power amps. All because nobody wants to control volume using bits.

I definitely considered this for my DIY active systems but decided to pass after I dug in to the specs and saw the noise performance.

Michael

 

[PeteL]

Why is 16 bit data an issue? A 32 bit DAC (or DSP) will happily attenuate 16 bit with essentially no quantization error for the vast majority of attenuation levels. Here is a digital measurement of a 32 bit DSP with a 1 kHz 16 bit input with 35 dB of attenuation, there is no quantization error and we maintain -96 dB THD+N. The limiting issue here will be analog noise from the DAC / amplifier and not quantization error from digital volume control.

View attachment 212455

I've used DSP in all my systems since my first forays in to car audio 15+ years ago so I have no issue with digitizing analog sources and these days ADC quality is so high I am quite confident that it will be nowhere near limiting compared to the analog source.

I agree that sensible gain structure is a prerequisite and unfortunately it is something that is often ignored. However I can assure you that I have very good understanding of the residual noise requirements at the speaker terminals to avoid speaker hiss with the speakers I use and it can be achieved with relatively middling pro audio DACs and Hypex / ICEPower amplifiers, see this thread for more info -> https://www.audiosciencereview.com/...m-china-with-topping-performance.24768/page-2.

I just don't see where this device fits in a modern world with digital volume control and low noise DACs, especially at the price.

Michael

I did not say 16 bits was an issue. I was responding to this statement: "32 bit, super low noise DACs digital is the way to go. I would even argue it is one of the few reasons that these 120+ dB DACs make sense," You don't get 120 dB from a 16 bits source.

 

[mdsimon2]

I did not say 16 bits was an issue. I was responding to this statement: "32 bit, super low noise DACs digital is the way to go. I would even argue it is one of the few reasons that these 120+ dB DACs make sense," You don't get 120 dB from a 16 bits source.

No but you can attenuate a 16 bit source with a 32 bit DAC by a significant amount and not lose any dynamic range because you are starting from such a high dynamic range in the first place which was my primary point.

We are probably just talking past each other at this point.

Michael

 

[PeteL]

No but you can attenuate a 16 bit source with a 32 bit DAC by a significant amount and not lose any dynamic range because you are starting from such a high dynamic range in the first place which was my primary point.

We are probably just talking past each other at this point.

Michael

Yes 32 bits processing can allow that flexibility. Do you know any such device with 8 digital IO with a knob to digitally attenuate volume of all 8 channels? I don’t know any AVR that can give the performance you measured.

 

[mdsimon2]

Yes 32 bits processing can allow that flexibility. Do you know any such device with 8 digital IO with a knob to digitally attenuate volume of all 8 channels? I don’t know any AVR that can give the performance you measured.

My motivation is DIY active speakers so I only need 2 in / 8 out and 8 I/O is a bit tougher. A miniDSP DDRC-88D would do it as would an Okto dac8 Pro. If you can get your source in to the digital world from an ADAT input or directly from your computer then there a lots of multichannel pro audio DACs or DSP softwares that will do it.

Personally I use an Okto in my main system and a MOTU Ultralite Mk5 in my second system. In the main system I use the Okto for volume control as it has a great display and excellent IR remote response and in the second one I use CamillaDSP as the MOTU itself doesn’t have IR remote control. Both are dead silent from the listening position even with amplifiers connected directly to tweeters with no padding.

Michael

 

[PeteL]

My motivation is DIY active speakers so I only need 2 in / 8 out and 8 I/O is a bit tougher. A miniDSP DDRC-88D would do it as would an Okto dac8 Pro. If you can get your source in to the digital world from an ADAT input or directly from your computer then there a lots of multichannel pro audio DACs or DSP softwares that will do it.

Personally I use an Okto in my main system and a MOTU Ultralite Mk5 in my second system. In the main system I use the Okto for volume control as it has a great display and excellent IR remote response and in the second one I use CamillaDSP as the MOTU itself doesn’t have IR remote control. Both are dead silent from the listening position even with amplifiers connected directly to tweeters with no padding.

Michael

Yes, I think the knob itself is a key feature tough. I am still on a stereo setup for movies, but if Iwas to multi channel I don’t think I could live without an actual physical control. That leaves This with high performance DAC, or AVRs, not sure what would in the end give the best performance at the speakers, in the endthat’s what matters.

Edit: I didn´t realize the device you mentioned had a control wheel.

 

[mdsimon2]

Yes, I think the knob itself is a key feature tough. I am still on a stereo setup for movies, but if Iwas to multi channel I don’t think I could live without an actual physical control. That leaves This with high performance DAC, or AVRs, not sure what would in the end give the best performance at the speakers, in the endthat’s what matters.

The DDRC-88D, Okto and Ultralite Mk5 all have volume control knobs although the Okto is by far the nicest. The Mk5 knob is rather small and the DDRC-88D doesn’t have a display (although one can be DIYed rather easily with minidsp-rs). I’ve been meaning to DIY a better knob for my Ultralite Mk5 + CamillaDSP setup but just haven’t gotten around to it. I have some nice rotary encoders on hand but just need to write some code.

I am just not sure when the SPL makes sense. If you are doing multichannel you are a probably sticking with your AVR for volume control.

For stereo DIY active it is not hard to beat the performance of the SPL with a decent DAC. Both the MOTU Ultralite Mk5 and the Okto dac8 pro are lower noise than the SPL. Heck a RME Fireface 800 from the mid 2000s (available for ~$400 used) can actually beat the Okto in terms of residual noise if used on the lowest output setting. If you are adverse to DIY or using the DAC volume control I think it makes more sense to add a digital output miniDSP Flex on the front end of your system for volume control / indication. Will definitely give you better system SNR with any decently low noise DAC than the SPL.

Michael

 

[audio2920]

we bought a Denon AVR-x3700h and I did a network based volume controller with an arduino.

Ha, what a neat idea! How did you get audio to the 3700? Straight out of the Avid(?) on to HDMI?

 

[Rja4000]

The Mk5 knob is rather small

But, being a Midi device, you can easily attach a bigger Midi control to it

 

[PeteL]

I should have specified what I meant. I want my preamp/attenuator to allow me to optimize my gain structure and be like a wire at unity gain.

We all do, I still doubt the degradation is audible really, maybe the .75 dB channel difference at high volume is theoretically audible, but still, it's a bit difficult to blame "Implementation" when we can't really find any other measurements of an 8 gang (or should it be 16? it's balanced operation) potentiometer. Design choices maybe, some would think it should be done digitally, or with an other digitally or relay controlled tech which may be a bit much to ask for 8 balanced channels. SPL don't believe that and it's debatable, but implementation is hard to fault once you made this choice. This is also cheaper than all the devices you refer to, as an aside, but in the end they are different devices with different use case. I believe that this level of performance may really well be good enough.

 

[PeteL]

I definitely considered this for my DIY active systems but decided to pass after I dug in to the specs and saw the noise performance.

Michael

That's a fair point, but even if the performance was a pass, I read trough the manual and I don't see evidence of a routing matrix anyway. I think it really should be viewed as a monitor controller, I don't think there is a way to make this a stereo in- multi out device, unless maybe you would have a way to copy the stereo to many ins?

 

[BostonJack]

As a side comment: I've been sketching out a design for a simple integrated amp that uses other people's circuits in my chassis. something like: neurochrome active pre-amp with one balanced input, two RCA inputs, no phono, simple Alps pot volume control, and XXX module class D amplifier in the power range of, say, 60 - 80 Wpc @ 8 ohm.

I looked at an Arduino for display management and various relay controlled step devices for volume control and concluded: "Damn, this stuff adds expense at a pretty horrible rate!". I'm not very critical of price for these types of devices as the price floor for quality volume control is quite high.

I still have no idea what the XXX module class D amps should be.

 

[mdsimon2]

That's a fair point, but even if the performance was a pass, I read trough the manual and I don't see evidence of a routing matrix anyway. I think it really should be viewed as a monitor controller, I don't think there is a way to make this a stereo in- multi out device, unless maybe you would have a way to copy the stereo to many ins?

The use case would be on the output of an analog signal processor or a multichannel DAC / DSP so you are already dealing with 8 channels of output, exactly as described by @617 in the post I was replying to.

Some speaker diy people also use devices like this to control all 8 channels of an active 4 way speaker like a linkwitz lx521. You send a digital signal to a minidsp, which then outputs 8 channels of digital audio to 4 different stereo dacs. You then attenuate the dac with this device before sending to 8 power amps. All because nobody wants to control volume using bits.

I considered it exactly for the reasons he mentions, I had it drilled in to my head over the years that digital volume control = loss of resolution. It wasn't until I really dug in noise performance of DAC / amp combinations that I started to understand how hard it is to beat digital volume control these days. Using this device with say a miniDSP 4x10HD does make some sense as the miniDSP is not particularly quiet and depending on your system you can see a 10+ dB improvement in SNR at attenuated levels. Here is a model of that using a Hypex NC252MP amplifier and balanced output of a 4X10HD. Blue trace is 4X10HD by itself and orange trace is with SPL doing volume control.

The issue of course is that once you switch to a remotely high performance DAC the SPL actually hurts SNR. Here is the same model but using a MOTU Ultralite Mk5 (~110 dB SNR at 2 V output). At this point the SPL just adds noise.

Michael

 

[Ra1zel]

At this point the SPL just adds noise.

And if we model for RME ADI-2 or Topping D90se, SPL is left far far behind

 

[PeteL]

The use case would be on the output of an analog signal processor or a multichannel DAC / DSP so you are already dealing with 8 channels of output, exactly as described by @617 in the post I was replying to.



I considered it exactly for the reasons he mentions, I had it drilled in to my head over the years that digital volume control = loss of resolution. It wasn't until I really dug in noise performance of DAC / amp combinations that I started to understand how hard it is to beat digital volume control these days. Using this device with say a miniDSP 4x10HD does make some sense as the miniDSP is not particularly quiet and depending on your system you can see a 10+ dB improvement in SNR at attenuated levels. Here is a model of that using a Hypex NC252MP amplifier and balanced output of a 4X10HD. Blue trace is 4X10HD by itself and orange trace is with SPL doing volume control.

View attachment 212503

The issue of course is that once you switch to a remotely high performance DAC the SPL actually hurts SNR. Here is the same model but using a MOTU Ultralite Mk5 (~110 dB SNR at 2 V output). At this point the SPL just adds noise.

View attachment 212504

Michael

But then according to your use case (active speaker system), wouldn't the top model be the only relevant one? I don't think you can do cross-over with a Motu Mk5, or any non-DSP interface correct? The benefit of the analog volume control in this model seems quite significant compared to controlling the volume digitally no? I am sure there are quieter DSP units, yes but still, this is a standard and all will have to eat some digital headroom for processing, am I wrong?

 

[mdsimon2]

But then according to your use case (active speaker system), wouldn't the top model be the only relevant one? I don't think you can do cross-over with a Motu Mk5, or any non-DSP interface correct? The benefit of the analog volume control in this model seems quite significant compared to controlling the volume digitally no? I am sure there are quieter DSP units, yes but still, this is a standard and all will have to eat some digital headroom for processing, am I wrong?

Add a $55 RPi4 running CamillaDSP to that MOTU Ultralite Mk5 and you now have something with a more powerful DSP than any miniDSP, better noise performance across all volume levels and tons more I/O options.

15 years ago something like the miniDSP 4x10HD plus a SPL Volume8 may have made sense but now you can get better performance across any objective measure for less money than the SPL Volume8 itself.

Michael

 

[wisechoice]

15 years ago something like the miniDSP 4x10HD plus a SPL Volume8 may have made sense but now you can get better performance across any objective measure for less money than the SPL Volume8 itself.

Michael

You could if the Motu (or likewise, for a little more the Okto Dac8, or the RME UCX II) was still available. It’s sort of amazing how this conversation is unfolding without regard for what’s actually obtainable in the real world. But things have changed rather quickly in recent times.

 

[mdsimon2]

You could if the Motu (or likewise, for a little more the Okto Dac8, or the RME UCX II) was still available. It’s sort of amazing how this conversation is unfolding without regard for what’s actually obtainable in the real world. But things have changed rather quickly in recent times.

I'm using it as an example because it is what I actually use (instead of a miniDSP) and it has decent but not SOTA analog performance. Tons of other pro audio devices have similar performance, ones that come to mind off the top of my head...MOTU Ultralite AVB es, MOTU 8A, MOTU 624, MOTU 828es, MOTU 624, RME UCX series, RME UFX series, RME Fireface 802. I've mentioned this already in this thread but a RME Fireface 800 has better noise performance on the lowest output setting (-10 dBV) than an Okto dac8 pro and has been available since 2004.

If you want to talk availability the miniDSP 4x10HD has been out of stock longer than the Mk5...

Michael

 

[PeteL]

Add a $55 RPi4 running CamillaDSP to that MOTU Ultralite Mk5 and you now have something with a more powerful DSP than any miniDSP, better noise performance across all volume levels and tons more I/O options.

15 years ago something like the miniDSP 4x10HD plus a SPL Volume8 may have made sense but now you can get better performance across any objective measure for less money than the SPL Volume8 itself.

Michael

Interesting, I do have a 2x4 HD at the moment, but always listening if I can get better actual audible performance. Can you quickly let me know the signal flow, like where is the PI in the chain and connected how?
To be fully honest, I do have a PI somehere in a drawer, looks like it’´s a PI3, and also a 8 channel focusrite scarlett interface that does nothing at the moment, Had use for it in the past. Probably not SOTA. Did I purchase a 2x4 for no reason? My use case is typical, sub cross over and bass management. I have analog sources, and converted from digital sources, connected to a freya preamp.