Searching for AVR with Dirac and service manual

[Vincentponcet]

As it seems impossible to get a decent audio performance from an off the shelf AVR, it seems we can only use external DAC to get proper audio performance.
Sadly, an pre/pro with digital outs is 5-10 times more expensive than a simple AVR with analog outs, which sounds crazy, but it is what it is.
So, I'm looking for one which has the functionalities I'm looking for ie ATMOS + Dirac Live, and for which I could find the service manual, as it is possible to get the I2S signal before the DAC chip and to send it to an SPDIF/AES encoder to be able to use a proper external DAC.

I searched service manuals for recent AVRs to validate if this is doable, but I cannot find those.
Any ideas?

 

[Vincentponcet]

The difference between 97dB SINAD and 120dB SINAD is not audible so there is no practical benefit to doing this, FYI. If you want to do it anyway for engineering fun, ignore me

This does not explain why they cannot reach the performance of a <100$ DAC.

And we don't listen at 0dbfs, more probably at -20dbfs, so you take that hit too, to be at 77db Sinad. The preout are at low level, at 1V, so you take this hit too when used with an external amp.

I searched for the Denon 3700 service manual, but I didn't found it.
The engineering is not amazing, just soldering 4 cables to a board. It is even more unbelievable why they don't simply do it.
Those units have a ton of useless features like massive inputs/outputs rear panel. Many ADCs, connectors, all those money trashed that's very sad.
I just need digital in / digital out.
Even for the same price( ie 1500$), I would buy it, but this doesn't exist unless spending 15k$, just non sense.

 

[retro]

I'm really interrested in this aproach too..! In fact, I have considered getting a "cheap" AVR with Atmos and give it to one local guru who builds dac's, amps and so on, and let him have a go at it. Just haven't pulled the trigger..

In my case, I wouldn't use separate dac's, but instead feed the digital outs into a Lynx AES 16-channels digital input card in my HTPC, and do all the signal processing there. In my case then, Dirac isn't needed in the AVR, since I already have it in the pc, and I also have Audiolense license. Jriver is the player I use, and it's extremly capable in signalrouting etc..

Look forward to see what you find out about this!

@Weeb Labs, are you reading this....?

 

[Weeb Labs]

@Weeb Labs, are you reading this....?

I am now.

I searched service manuals for recent AVRs to validate if this is doable, but I cannot find those.
Any ideas?

Glad to see people stumbling upon my content! Regarding the service manuals, you may be able to forgo them entirely. If you can visually identify your AVR's DAC and locate the corresponding datasheet, that will enable you to determine the appropriate pins to poke.

Additionally, you will find that most SKUs within a particular generation of AVRs are essentially identical in layout. I would suggest having a look at the service manual for the X3500H.

 

[tvrgeek]

Which is why I am sticking with my Anthem. Sounds pretty good, though one dealer was really hot on the bigger NAD. I'm not sold on class D yet, but it seems to be getting better.

On audio quality though, I guess if you do your serious music listening to the HT system, then the DAC and DSP processing is below par, but for movies, not so sure. Personally, I keep my serious listening in the living room with a stereo. ( and $100 DAC) and find the AVR to be sufficient.

One can hang a decent 3 channel amp, Outlaw maybe, on any AVR and take the power supply load of the rest of the channels which do not need much fidelity anyway.

 

[Vincentponcet]

There's no market incentive for Dolby to permit cheap piracy devices like that.

The piracy is made from the movie support, ie the streaming source or the bd-uhd.
AV pre/pro with digital out exist. It is just available on very expensive boxes like jbl-sdp65, trinnov, stormaudio, so it is not forbidden.

 

[abdo123]

So in general the amplifier ends up the bottleneck anyways, not the DAC.

That’s not true.

 

[abdo123]

If your DAC and amplifier SINADs are both 100dB, the resulting SINAD of the chain is 97dB. If it's 100(dac)+90(amp), the resulting SINAD is 89.6 eg the amplifier

The average SINAD of amplifiers is 79dB, and about 100dB for DACs, so what I said was correct.

I’m going to quote myself from another thread:

“the Denon X3700H has dynamic range of 108 dB @ 2Vrms. lets do some math shall we?

The Denon will have 8uV of residual noise, a typical amplifier has around 29dB of gain. That is a voltage gain of 28 times. So the DAC contribution to the noise will be roughly 224uV.

A really good power amplifier with say 150WPC may have a S/N of 120dB plus (Hypex, Purifi, Benchmark), which will mean a residual of around 35uV, so the D/A's contribution is well over six times the amplifier's and the two will combine to become audible when the volume is high. That example would result in a S/N of ~104.5dB, a degradation of 15.5 dB from a 120dB rated amplifier. “

So yeah a lot of affordable amplifiers (NC502 with 600 WPC is like a bit over 600$) easily exceed the best AVR we have.

 

[abdo123]

a) What's the point of your calculation when it only includes noise and not distortion? We already have SINAD. And the SINAD of the NC502 is only about 94dB.

AVRs are usually runing at -30 dBFS (THX reference level) or even lower depending on the room correction algorithm, so the typical use case Harmonic distortion is way lower than what Amir measures (for both Processors and amplifiers).

Harmonic distortion is also mostly benign, it is unequivocally dominated by the speakers. it has to go above 1% (40 dB SINAD) in electronics for me to hear it with test tones. My opinion might change if I get something like the Stealth headphones.

So because of these two, S/N is extremely important because you're losing 30 dB of it from the start and it is an actual audible metric, while SINAD is not.

a) What's the point of your calculation when it only includes noise and not distortion? We already have SINAD. And the SINAD of the NC502 is only about 94dB.
b) We are talking about home theatre AVRs. $300/channel means you're telling people to spend $3300 on amplifiers for an 11-channel setup, when they only paid $1500 for their Denon. That makes no sense and is an absurd waste of money for completely inaudible benefits. You buy NC502 for multi-channel setups only when you have money to burn and already spent like >$10K on speakers.

you really think 3300$ for state of the art 11-channel amplification is expensive? wow lol. I have no comment on that.

 

[abdo123]

Sorry, I completely disagree, they're both pointless metrics.

Then I question your ability to hear. I can hear the hiss of DACs with 90dB to 100 dB S/N easily.

Amir in the Directiva review complained about the hiss caused by the MiniDSP 2*4 HD which has 95 dB S/N. Audibility of noise is not up to debate for me. sorry.

ASR Directiva Open Source Speaker Review

As some of you know, we have had a project to design an open-source speaker based on Purifi driver. It has been led by our member, @Rick Sykora who has named it "Directiva." You can read about it here...

www.audiosciencereview.com

 

[tvrgeek]

I think both sides lamenting the poor quality of an AVR are correct. I find the amplifiers to be seriously lacking in the kind of engagement I get from my Stereo. Flat not enough transistor pairs, transformer, or main caps. A "decent" 100W amp will weigh over 20 Lbs per channel. So for just getting to "decent" 5.1 we would be talking 200 Lbs and a 12U cabinet. It would require dedicated electrical service. Using the better class D would help, but right now, a half decent class D still costs as much as A/B and is not smaller or lighter.

AND, the DAC quality is not up to 1980 standards yet. 15 crappy channels. Do I care my new Ultra disks are 24 bit when we get 14 bits of performance out of the DAC? How about three really good ones and the rest crappy?

Most AVRs are sold by features and "power" with product lines containing power in 10W increments, even though we know that is totally garbage.

Anyway, if I want to listen to music, I use my stereo. If I want tolerable movies, I am keeping my old 5.1 Anthem as it is not great, but not terrible either.

 

[Chromatischism]

The engineering is not amazing, just soldering 4 cables to a board. It is even more unbelievable why they don't simply do it.
Those units have a ton of useless features like massive inputs/outputs rear panel. Many ADCs, connectors, all those money trashed that's very sad.
I just need digital in / digital out.

Who are you to say they have "useless" features and the money is "trashed" and "very sad"? Maybe someone uses all of those channels and features? Speaking for myself, I have a 5.1.4 system with 2 subs and I get quite a bit of use out of my AVR.

Maybe it's just the language barrier and what you mean is it would be a waste to you in your use case. That is fine.

However, I disagree with the premise of your post:

As it seems impossible to get a decent audio performance from an off the shelf AVR, it seems we can only use external DAC to get proper audio performance.

 

[Chromatischism]

Then I question your ability to hear. I can hear the hiss of DACs with 90dB to 100 dB S/N easily.

Amir in the Directiva review complained about the hiss caused by the MiniDSP 2*4 HD which has 95 dB S/N. Audibility of noise is not up to debate for me. sorry.

ASR Directiva Open Source Speaker Review

As some of you know, we have had a project to design an open-source speaker based on Purifi driver. It has been led by our member, @Rick Sykora who has named it "Directiva." You can read about it here...

www.audiosciencereview.com

I don't know about you, but I don't listen to my system at 2 feet.

 

[abdo123]

I don't know about you, but I don't listen to my system at 2 feet.

Oh i sit 16 feet away from my system and i hear it loud and clear. Amir wasn’t overexagerating. He probably uses a high gain amplifier for his tests.

 

[Chromatischism]

I don't think the "hiss" is represented in the 95 dB S/N though, is it? Normally we associate that with the ADC in powered speakers and not the DAC. If so, that's pretty bad.

 

[abdo123]

I don't think the "hiss" is represented in the 95 dB S/N though, is it? Normally we associate that with the ADC in powered speakers and not the DAC. If so, that's pretty bad.

When Amir measured it there wasn't a that much of a difference in noise between inputs.

 

[Vincentponcet]

Who are you to say they have "useless" features and the money is "trashed" and "very sad"? Maybe someone uses all of those channels and features? Speaking for myself, I have a 5.1.4 system with 2 subs and I get quite a bit of use out of my AVR.

Maybe it's just the language barrier and what you mean is it would be a waste to you in your use case. That is fine.

However, I disagree with the premise of your post:

Yes I was talking "in my use case".

 

[Chromatischism]

AND, the DAC quality is not up to 1980 standards yet. 15 crappy channels. Do I care my new Ultra disks are 24 bit when we get 14 bits of performance out of the DAC?

*18 bits

Denon AVR-X3700H AVR Review

This is a review and detailed measurements of Denon AVR-X3700H 9.2 channel 8K Home Theater AV Receiver (AVR). It is kindly loaned to me by a local member and costs US $1,199. Visually, if you have seen one AVR, you have seen the look of the AVR-X3700H: The input selector is plastic and...

www.audiosciencereview.com

 

[Miker 1102]

I grew up in movie theaters becaue my family managed the local cimema complexes 47 years out of of my 51. I remember what movies sounded like in the 70s and how the new speaker systems rolled in with thx in the 80s and then full digital, etc. What I have in my basement ..nine speakers, computer controlled calibration, dual subwoofers, a high Def film library...is beyond my wildest 70s childhood fantasy. A modern avr is an incredibly wonderful gift. I have one that I bought for $289. It bench tested fairly well. It sounds amazing in 24/48 with Steven Wilson's Yes mixes in 5.1. I unnerved my wife playing Pink Floyd Wish You Were Here in surround sound. The atmos movies are superb..Dune UHD is one of best soundtracks I ever heard. Three cheers for Avrs!