Receiver Preamp Outputs vs Dedicated Preamps

[KA7NIQ]

I was always a 2 channel guy, always using a separate dedicated preamp to drive my amplifier. As I moved into multi channel, I started using receivers, and many of these had preamp outputs. One day, I decided to compare my dedicated preamp, with my receivers preamp outputs. I heard absolutely no difference between my dedicated preamp, and the preamp outputs of my receiver driving my amplifier. Has anyone any comments on this ? Is there any reason a high end receivers preamp outputs can not equal a dedicated preamp sonically ?

 

[DVDdoug]

I wouldn't expect a difference. A "preamp" does almost nothing to a line-level analog signal except for the effects of bass/treble controls, etc. Mostly it's a switching & control center. Much of the time it's operating as an attenuator rather than an amplifier. (If you are using a turntable, then you actually have a preamp.)

A modern receiver with digital/electronic volume control will probably "track" left & right volume better than a pot in an older preamp.

 

[Chrispy]

My general experience with several avrs with preouts and a variety of amps. I'm no "ampliphile" in any case, but only a capability difference and that can be hard to tell unless you push the envelope so to speak. They all did fine and mostly the avr was fine on its own too. Using measurements of dedicated pre-pros vs avrs, seems no problem to use an avr at the better economy of scale pricing to use as a pre-pro unless you're just paranoid about heat/other electronics in the same box.

 

[dlaloum]

I was always a 2 channel guy, always using a separate dedicated preamp to drive my amplifier. As I moved into multi channel, I started using receivers, and many of these had preamp outputs. One day, I decided to compare my dedicated preamp, with my receivers preamp outputs. I heard absolutely no difference between my dedicated preamp, and the preamp outputs of my receiver driving my amplifier. Has anyone any comments on this ? Is there any reason a high end receivers preamp outputs can not equal a dedicated preamp sonically ?

So the answer is - it's complicated... literally

A basic traditional analogue pre-amp has to do only two things - clean gain, and switching inputs

A modern AVR has DAC's, ADC's, CPU, GPU, Bluetooth/Network interface, and power amps.

The potential problem areas are all the digital stuff and its potential for noise/hash, (and jitter).

Depending on the AVR, it may or may not have "proper" pure analogue in and out - but in all cases, as soon as you engage any of its DSP functions (cross overs, bass management, Room EQ, surround modes, etc...) - your incoming signal will, if analogue, be passed through the ADC's, converted to digital, and then processed, before going through the DAC's and then to the outputs.

If your incoming signal is digital - then in "pure" mode (for those AVR's that have it) - your signal shoudl be passed straight to the DAC's and out the pre-out - but again, if you engage any processing, it will go through the DSP - and, typically, as the processing is limited to 48kHz, if your incoming stream is over 48Khz it will get downsampled before processing, and then output to the DAC's (in downsampled and processed form).

So there are a lot more steps in the chain potentially, there are a lot more circuits that need to be paid attention to in the design/engineering process, and it is harder to achieve a good clean output...

Having said all that - sites like this one, and the tests that AmirM puts various pieces of equipment through, are one good way of determining how "clean" a specific AVR will be.

A good one should be indistinguishable from a basic preamp (says theory...)

Amir's tests have shown some very well known upmarket brand names in this space, have been a little slipshod in their circuitry hygiene - and their output SINAD is not as clean as it should be.

On the other hand, tests of the Denon AVR's, and the recent Onkyo AVR showed very good preout results.

 

[dlaloum]

P.S. I have been using a TOTL Onkyo AVR as a Stereo pre for music since circa 2009 - and am planning to upgrade to a current generation one shortly... yes it does double duty for home theatre/surround - but it is also my Stereo music system - running into external power amps.

 

[KA7NIQ]

I wouldn't expect a difference. A "preamp" does almost nothing to a line-level analog signal except for the effects of bass/treble controls, etc. Mostly it's a switching & control center. Much of the time it's operating as an attenuator rather than an amplifier. (If you are using a turntable, then you actually have a preamp.)

A modern receiver with digital/electronic volume control will probably "track" left & right volume better than a pot in an older preamp.

Years ago, I bought some truly awful speakers that my best friend still owns. They were from a company called VMPS and the Model was the VMPS RM 40. I kept them about 6 months, and threw several amplifiers at them, all with poor results! So, I sold them. However, my friend still has his pair, and told me today that "because I used a receiver with preamp outputs on them, I never gave them a chance" ! He has a dedicated 2 channel system, with a separate dedicated 2 channel preamp that is fully balanced. In fact, his DAC, Preamp, and Amplifier are all balanced. I have been down that road before years ago. I never heard any difference between a fully balanced system, and one using RCA Cables. Several of my amplifiers are balanced only, so I go from the RCA Cables of my receiver pre outs to XLR Connectors into the amps. It works just fine!

 

[KA7NIQ]

So the answer is - it's complicated... literally

A basic traditional analogue pre-amp has to do only two things - clean gain, and switching inputs

A modern AVR has DAC's, ADC's, CPU, GPU, Bluetooth/Network interface, and power amps.

The potential problem areas are all the digital stuff and its potential for noise/hash, (and jitter).

Depending on the AVR, it may or may not have "proper" pure analogue in and out - but in all cases, as soon as you engage any of its DSP functions (cross overs, bass management, Room EQ, surround modes, etc...) - your incoming signal will, if analogue, be passed through the ADC's, converted to digital, and then processed, before going through the DAC's and then to the outputs.

If your incoming signal is digital - then in "pure" mode (for those AVR's that have it) - your signal shoudl be passed straight to the DAC's and out the pre-out - but again, if you engage any processing, it will go through the DSP - and, typically, as the processing is limited to 48kHz, if your incoming stream is over 48Khz it will get downsampled before processing, and then output to the DAC's (in downsampled and processed form).

So there are a lot more steps in the chain potentially, there are a lot more circuits that need to be paid attention to in the design/engineering process, and it is harder to achieve a good clean output...

Having said all that - sites like this one, and the tests that AmirM puts various pieces of equipment through, are one good way of determining how "clean" a specific AVR will be.

A good one should be indistinguishable from a basic preamp (says theory...)

Amir's tests have shown some very well known upmarket brand names in this space, have been a little slipshod in their circuitry hygiene - and their output SINAD is not as clean as it should be.

On the other hand, tests of the Denon AVR's, and the recent Onkyo AVR showed very good preout results.

I have an ONKYO TX RZ 830 that allows going "direct", but you are correct,, once any digital feature is turned on, it goes through the ADC. However, some so called "High End" 2 channel preamps use ADC to get some "gee whiz" features, and are not the straight through analogue designs from years past.

 

[dlaloum]

I have an ONKYO TX RZ 830 that allows going "direct", but you are correct,, once any digital feature is turned on, it goes through the ADC. However, some so called "High End" 2 channel preamps use ADC to get some "gee whiz" features, and are not the straight through analogue designs from years past.

I've been happy with the SPDIF inputs of my 2008 SR876, and 2013 DTR 70.4... less so with the HDMI inputs on that generation... which have 10x the jitter that the SPDIF has. (not noticeable on HT, but noticeable on stereo.... course it could be psychological)

The current generation has far less jitter on the HDMI (and I have a feeling this has been the case for a few years now - so may be applicable to the RZ830) - so using HDMI as the universal interface is becoming more of a viable thing.

I only use analogue inputs for Vinyl nowadays.... and my turntables have been in protected storage for a few years due to "ankle biter" risk. (One TV was destroyed by a balistic Thomas tank engine.... and is far more replaceable than the vintage turntables)

 

[KA7NIQ]

I've been happy with the SPDIF inputs of my 2008 SR876, and 2013 DTR 70.4... less so with the HDMI inputs on that generation... which have 10x the jitter that the SPDIF has. (not noticeable on HT, but noticeable on stereo.... course it could be psychological)

The current generation has far less jitter on the HDMI (and I have a feeling this has been the case for a few years now - so may be applicable to the RZ830) - so using HDMI as the universal interface is becoming more of a viable thing.

I only use analogue inputs for Vinyl nowadays.... and my turntables have been in protected storage for a few years due to "ankle biter" risk. (One TV was destroyed by a balistic Thomas tank engine.... and is far more replaceable than the vintage turntables)

I have always been told that Coaxial is better than Optical, more bandwidth

 

[dlaloum]

I use the term SPDIF interchangeably for both coax and optical.... currently running optical, as that was easiest for my temporary setup... pending arrival of new AVR, and after my DTR 70.4 relased its magic smoke... reverted to my SR876, which has no HDMI as that board relased it's magic smoke some years back... and no spares are available for either!

 

[KA7NIQ]

I use the term SPDIF interchangeably for both coax and optical.... currently running optical, as that was easiest for my temporary setup... pending arrival of new AVR, and after my DTR 70.4 relased its magic smoke... reverted to my SR876, which has no HDMI as that board relased it's magic smoke some years back... and no spares are available for either!

I have not read any receiver reviews here lately, but it would be useful if Amir tested the preamp outputs of receivers he tests.

 

[dlaloum]

I have not read any receiver reviews here lately, but it would be useful if Amir tested the preamp outputs of receivers he tests.

He does...

 

[JeffS7444]

I was always a 2 channel guy, always using a separate dedicated preamp to drive my amplifier. As I moved into multi channel, I started using receivers, and many of these had preamp outputs. One day, I decided to compare my dedicated preamp, with my receivers preamp outputs. I heard absolutely no difference between my dedicated preamp, and the preamp outputs of my receiver driving my amplifier. Has anyone any comments on this ? Is there any reason a high end receivers preamp outputs can not equal a dedicated preamp sonically ?

My limited experience with using receivers as preamplifiers is that sometimes corners get cut, and high output impedance may make them less suited for driving longer cables: In such situations, you may either get no sound, or it may be weak and distorted. But used with less demanding loads, it should be fine.

 

[dlaloum]

My limited experience with using receivers as preamplifiers is that sometimes corners get cut, and high output impedance may make them less suited for driving longer cables: In such situations, you may either get no sound, or it may be weak and distorted. But used with less demanding loads, it should be fine.

Typically AVR's as Preamps only have unbalanced RCA outputs, dedicated Preamps have XLR Balanced outputs.

RCA with long runs, results can vary - balanced XLR is specifically designed for long runs.

But if, as is typically the case, the amp is right under/above the preamp, then this is not a big deal! - and 5m RCA runs have typically not been an issue for most people

 

[keepthingsclean]

that´s also exactly my topic at the moment.
Should I be bothered to just use the pre-amp of the AVR in Pure Direct mode to run my DAC or Phono Outputs from the RCA to the power amplifier... or is there still some tinkering going on in between so that I should rather consider to feed the music sources into an integrated stereo-amp or dedicated stereo pre-amp with HT Bypass options and wire the AVRs L/R channel into that.

My uncertain mind tells me, that the previous Arcam Stereo Integrated was more "alive" than the current AVR plus Power-Amp setup. Too bad i had to sell it, so that I couldn´t do a side by side comparison.

 

[dlaloum]

that´s also exactly my topic at the moment.
Should I be bothered to just use the pre-amp of the AVR in Pure Direct mode to run my DAC or Phono Outputs from the RCA to the power amplifier... or is there still some tinkering going on in between so that I should rather consider to feed the music sources into an integrated stereo-amp or dedicated stereo pre-amp with HT Bypass options and wire the AVRs L/R channel into that.

My uncertain mind tells me, that the previous Arcam Stereo Integrated was more "alive" than the current AVR plus Power-Amp setup. Too bad i had to sell it, so that I couldn´t do a side by side comparison.

Depends on the brand - watch for the terminology differences - on my old Onkyo "Pure Audio" - meant no processing - analogue IN remains analogue all the way through, and Digital IN gets converted by the DAC's and that's all... no processing.

Whereas "Direct" will get converted, it minimises DSP processing, but if you have a crossover, are bi-amping etc... it will process the signal - but it won't apply any upmixing/downmixing, surround effects and such.

On other brands (or the same brand a few years later!) the terms will mean different things.

You need to check your own AVR's manual/specs

 

[Chrispy]

Depends on the brand - watch for the terminology differences - on my old Onkyo "Pure Audio" - meant no processing - analogue IN remains analogue all the way through, and Digital IN gets converted by the DAC's and that's all... no processing.

Whereas "Direct" will get converted, it minimises DSP processing, but if you have a crossover, are bi-amping etc... it will process the signal - but it won't apply any upmixing/downmixing, surround effects and such.

On other brands (or the same brand a few years later!) the terms will mean different things.

You need to check your own AVR's manual/specs

Reminds me of difference between Direct and Pure Direct on Denons these days at least, where Pure Direct just means it turns off the video/panel display circuit. Then again some Denons used to have the pure analog processing via "ext-in" analog inputs, but those have largely gone away.