Where is the Flaw in most Multichannel Preamps/ AVRs?

[Fredygump]

I searched through all of Amir's reviews of multichannel preamps, and I made a list of all the ones that have balanced outputs. The rest of my system has balanced interconnects, and I want to keep the entire analog signal chain balanced if possible.

So I made a list, and the recurring theme is that these devices do not seem to perform very well compared to modern DACs. My list:

Has anyone tried to dig any deeper to figure out where the performance issue comes from? Is it from processing the digital signal, or is it the DACs themselves?

I imagine with 16+ DACs in a single unit, a company would be tempted to choose something cheaper. But if the DACs were better, would the audio quality be better?

I'm asking because I recently bought a MiniDSP HTx, which rates top of the chart for SINAD...but it doesn't decode multichannel audio. And I don't have a multichannel preamp, though I'm curious about going that route.

What I'd like to know is, what happens if I get a relatively inexpensive AVR/ preamp that can decode the audio, and then send a digital signal to my HTx?

Would I end up with the high quality audio the HTx's review indicates it is capable of? Or would I still get the noisier/ lower quality audio described by the preamp reviews?

 

[kemmler3D]

if the DACs were better, would the audio quality be better?

This is a pretty fair question. In many cases the answer is actually no.

While Amir likes DACs and amps to provide >16 bits of noise and distortion free signal, in practice that's better than you can hear in many, perhaps most real-world listening situations. So often a "fair" quality AVR can still provide an effectively transparent signal.

Would I end up with the high quality audio the HTx's review indicates it is capable of? Or would I still get the noisier/ lower quality audio described by the preamp reviews?

In this case the HTX would be the limiting factor for the audio quality (digital will stay digital and not degrade) so you will get the good HTX sound quality.

 

[Fredygump]

This is a pretty fair question. In many cases the answer is actually no.

While Amir likes DACs and amps to provide >16 bits of noise and distortion free signal, in practice that's better than you can hear in many, perhaps most real-world listening situations. So often a "fair" quality AVR can still provide an effectively transparent signal.

In this case the HTX would be the limiting factor for the audio quality (digital will stay digital and not degrade) so you will get the good HTX sound quality.

The reason I'm asking about the audio quality is because of my experience with noisy devices. I purchased the HTx, because the inexpensive 4x8 signal processor I was using for my 4 way speakers was quite noisy, resulting in hissing from the horns....despite a -20dB pad on the horns! The HTx turns out to produce 1/10th the noise as my old processor, and now my horns are silent!

So I would be a little annoyed if I were to purchase an expensive processor, only to have this noise return! (But if routing through the HTx eliminate the noise, then I am free to purchase an inexpensive preamp?)

Another member showed me how to derive residual noise in µV from various specified measurements, and I'm making the lazy assumption that SINAD correlates to residual noise?

I'm a bit surprised that Amir doesn't measure this directly. I'm not an electrical engineer, and I'm not a believer in audio magic. I'm aware that, like you said, most devices won't create audible noise or distortion while playing music. But everybody will notice if there is hissing coming out of my speakers when there is nothing playing. So I feel this measurement may have more practical importance than all the other measurements.

 

[Keith_W]

I would be surprised if the hiss that you hear is coming from the DAC's SINAD. Are you sure that your cable isn't picking up interference from somewhere? Does the hiss go away when you use balanced?

 

[Blumlein 88]

Another member showed me how to derive residual noise in µV from various specified measurements, and I'm making the lazy assumption that SINAD correlates to residual noise?

SINAD may or may not correlate with residual noise. SINAD is THD+Noise. So a SINAD of -90 db could be very, very low noise of -120 db with some harmonic distortion at -90 db. Or it could be distortion at -120 db with noise which is at -90 db. You don't know just using that one number.

The measurement in Amir's reviews you want to look at is dynamic range. It will give you the noise level over 0hz to 20 khz vs max output level. From that you could get an idea of the microvolts of noise and with the gain of the rest of your gear get an idea if noise will be audible.

For instance the Monoprice HTP-1 has a dynamic range of 112 db relative to 4 volts output.

 

[Deleted member 58670]

I have tested the Anthem AVM 70 vs the MiniDSP flex balanced as pure 2-ch DACs, level matched within 0.1 dB. I own both. That’s 99 vs 114 dB SINAD. 3rd harmonic distortion on the MiniDSP is more than 20 dB lower than on the AVM70. Even so, I could not hear any difference what so ever, not even in a sighted listening test.

I guess both SINAD numbers are lower than anyone can detect by ear?

 

[Fredygump]

I would be surprised if the hiss that you hear is coming from the DAC's SINAD. Are you sure that your cable isn't picking up interference from somewhere? Does the hiss go away when you use balanced?

As mentioned in the original post, I'm using balanced cables for everything. It isn't ground loop. I know the difference; ground loop sounds completely different.

You probably don't mean to do so, but it feels like I'm being put on trial and interrogated every time I mention that electronic components produce noise. But it happens every time. Please just suspend your disbelief for a moment? I don't want to argue about this again.

 

[Fredygump]

SINAD may or may not correlate with residual noise. SINAD is THD+Noise. So a SINAD of -90 db could be very, very low noise of -120 db with some harmonic distortion at -90 db. Or it could be distortion at -120 db with noise which is at -90 db. You don't know just using that one number. The measurement in Amir's reviews you want to look at is dynamic range. It will give you the noise level over 0hz to 20 khz vs max output level. From that you could get an idea of the microvolts of noise and with the gain of the rest of your gear get an idea if noise will be audible.

For instance the Monoprice HTP-1 has a dynamic range of 112 db relative to 4 volts output.

Thanks! I wasn't sure how distortion factored into the SINAD rating.

 

[Dave Zan]

...I'd like... a relatively inexpensive AVR/ preamp that can decode the audio, and then send a digital signal to my HTx?

I am surprised no one has mentioned that the "flaw" is that you simply can't do this, at least not without difficulty.
The industry doesn't want bit-perfect copies, so inexpensive AVR's don't output a digital signal after they decode.

While the audibility may be debatable under typical conditions, it's a pain for owners of digital input active speakers, experimenters, and anyone who wants maximum performance. Edit (in view of later comments):
This "maximum performance" may be required for very efficient horn loaded speakers, that is the OP's as well as my personal motivation.
My rather reverberant room favours fairly directional horn speakers, and their sensitivity can exceed 110 dB/2.83 V. (1 W nominal at 8 ohms)
Amir's SINAD is usually referenced to 5 W nominal, so subtract 7 dB if it's noise dominated (as it typically is), that usually puts AVR noise well into the audible .

I still haven't seen an entirely satisfactory solution-
You can hack an inexpensive AVR, as shown >here<, thanks to @Weeb Labs , but only for the skilled.
>ARVUS< makes a decoder, but it's not cheap.
There are HDMI audio extractors, but I don't know of any AVR that puts out decoded audio on HDMI.
The JBL's have digital outputs, but are Dante, rather than a more common format, and they are not "inexpensive"
The very expensive AVRs can have options to do this, perhaps it will trickle down eventually.
In the meantime there have been many threads of complaints about this, hope the links above prompt a solution.

Best wishes
David

 

[Blumlein 88]

I re-read your opening post. I don't know if it works that way that an AVR preamp will decode and send a digital output. I think it will put out a digital output that still needs decoding into Dolby elsewhere. These AVRs would put out a digital signal not effected by their measured analog SINAD or dynamic range.

OK just saw Dave Zan's post and I do think he is correct.

It is one of the most frustrating things in video. One they aren't going to change because of money and a near monopoly.

 

[TonyJZX]

i think it says it all that dirac runs at 48khz

and so that is really good for 99.9% of audiences and well good enough for home theater

i remember some pretty expensive avp/avr used ESS 9018K2M all round and people didnt like that... if you spend $5k+ then you probably expect newer dacs

but in reality, would you hear the difference???

we know the AVR is a real EM mess inside with all kinds of high freq. signals running about

i think something like an SMSL SU-1 beats then all in signal clarity but obviously look at the circuit complexity... and also we have higher demands of music over mere.... netflix and movies?

 

[Fredygump]

I am surprised no one has mentioned that the "flaw" is that you simply can't do this, at least not without difficulty.
The industry doesn't want bit-perfect copies, so inexpensive AVR's don't output a digital signal after they decode.

While the audibility may be debatable under typical conditions, it's a pain for owners of digital input active speakers, experimenters, and anyone who wants maximum performance.
I still haven't seen an entirely satisfactory solution-
You can hack an inexpensive AVR, as shown >here<, if you are skilful.
>ARVUS< makes a decoder but it's not cheap.
There are HDMI audio extractors but I don't know of any AVR that puts out decoded audio on HDMI.
The very expensive AVRs can have options to do this, perhaps it will trickle down eventually.
In the meantime there have been many threads of complaints about this, hope the links above prompt a solution.

Best wishes
David

Ok. That makes sense with DHCP, I guess. But unfortunate.

I saw a video about the Audient Oria as a solution for studio use. It appears to be a similar idea to the ARVUS, but the Oria doesn't have HDMI. I think it just uses USB audio, AES.

I'm just starting to think about this stuff, contemplating on expanding my system, so I haven't found these other threads yet.

 

[YSDR]

I'm asking because I recently bought a MiniDSP HTx, which rates top of the chart for SINAD...but it doesn't decode multichannel audio.

If 7.1 channel is enough for you, then the HTx is enough, just set the output format to PCM on the source/player device so this latter will decode.

 

[zgmf_x10a]

people who think they can hear the differences between a modern AVR and a high SINAD need to prove it with level-matched blind tests.. I replaced a Motu M4 (100+ SINAD) with a TI X3700h and never looked back.

 

[Blumlein 88]

The op is not worried about SINAD. He is concerned about noise. Stop with the demands for him to prove something. He apparently has high sensitivity horn speakers. Those can be problematic with noise levels that are inconsequential with the speakers most of us have.

 

[Deleted member 58670]

If you hear noise with 100 dB SINAD, the gain structure of the system is terribly wrong imho.

 

[JSmith]

So I made a list, and the recurring theme is that these devices do not seem to perform very well compared to modern DACs.

Amps often have more distortion and noise compared to a well measuring DAC, especially AVR's with all the various systems packed in the one box.

What you need to ascertain when looking at the review measurements here is whether the SINAD figure is mostly noise dominated,distortion dominated or a mixture of both.

If you have high sensitivity speakers that show up noise more often that not, then you will need to ensure the device is not noise dominated in the measurements.

For example;

Anthem AVM70 Review (AV Processor)

This is a review and detailed measurements of the Anthem AVM70. It was sent to me by the company for review and costs US $3799. The AVM70 has a very modern and attractive front panel and display: Company takes full use of the large display as you see with nice icons. Importantly, the...

www.audiosciencereview.com

The above has little noise, SINAD is limited by 2nd and 3rd harmonic distortion, which is very low in level.

This video by our host may assist further;

JSmith

 

[Blumlein 88]

So watch the dynamic range portion of the above video. Starts just after the 10 minutes mark and goes for about 2 minutes.

 

[Kal Rubinson]

i think it says it all that dirac runs at 48khz

Dirac runs at 48kHz because it is limited by the hardware. It runs at up to 192kHz where the hardware is capable (e.g., PC/Mac/Linux boxes).

 

[mdsimon2]

AVRs typically have digitally controlled analog volume control so using SINAD / DR measurements at full output isn't indicative of residual noise at attenuated output levels. At lower output levels an analog volume control will provide lower noise than a digital volume control given the same full level dynamic range. This is why many use AVRs and don't report hiss issues. In addition, as mentioned by others, AVR SINAD is often dominated by distortion which is most less audible than noise.

Standalone DACs typically use digital volume control so need higher dynamic range to avoid hiss.

Using the analog output of an AVR into a miniDSP HTx would clearly result in more noise than just using the AVR itself, however I think such a system should still have acceptable noise performance. The noise at the output of the miniDSP will be a combination of noise from the AVR + ADC + DAC, therefore I think you will achieve the best noise performance by running the AVR at max volume into the ADC and using the miniDSP for volume control. As you lower the volume in the miniDSP, it will effectively attenuate the noise from the AVR and ADC.

A bit of quick modeling shows that if you are starting with an AVR that has 4V DR of 108 dB, after about 20 dB of attenuation in the miniDSP, the noise level will be very close to the noise level of the miniDSP DAC itself.

Of course, if you go the digital route into the miniDSP HTx with something like the Arvus, the only noise contribution will be from the miniDSP DAC.

Michael