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Passive Pre-Amp into Integrated Amp to Prevent Clipping?

On my previous system (DAC -> active speakers), I had some serious issue with clipping, even at low volume (volume was controlled by the active speakers). So I solved that by sticking a passive pre-amp (Schiit Sys which is a pot-based passive attenuator) in between the DAC and the active speakers. I used a 0 dbFS 60 Hz sine wave test tone (60 Hz because I would be sure my Fluke TrueRMS multimeter would measure it accurately since the Fluke is mainly used for home AC power applications) from my PC into the DAC-Preamp chain and measured the RCA output level with the multimeter at the SYS outputs. Then I turned the SYS volume down from 100% (measured 2 Vrms) until the multimeter measurement matched the active speakers’ input sensitivity (750 mVrms). Never touched the SYS volume knob again (I used the active speakers’ volume knob for adjusting listening level) and never had any clipping issues afterwards. And as they say, the rest is history. (Actually, if anybody has any feedback on my methodology, that’d be great).

Not quite. I finally decided to upgrade my system to one with passive speakers. The system I decided to go with is a Yamaha R-S202 stereo receiver with ELAC Debut 2.0 B6.2 speakers. The DAC hasn’t changed. (It’s an old DIY Ross Martin 24-bit DAC I was gifted from a friend. I don’t think Ross Martin is in business anymore because his website is down.)

The Yamaha receiver, being an integrated amp, already has a built-in pre-amp (I do not know if it has an active pre-amp stage or simply a passive volume control upstream of the power-amp section - does anybody know?). The spec’ed input sensitivity is 500 mVrms. Given that I had clipping issues with the old active speakers, which had a sensitivity of 750 mVrms, I assume that my clipping issues would get worse if I go DAC -> Yamaha?

Do I need to stick the SYS in between DAC and Yamaha (calibrate SYS volume to 500 mVrms output and do not change so I can use the full range of the Yamaha’s volume knob for adjusting listening level without ever clipping)? Would there be any disadvantages with respect to sound quality?

I did check the chain for proper impedance bridging. The minimum damping factors I calculated would be SYS/DAC = 13.74 and Yamaha/SYS = 17.74 so I wouldn’t be running into many issues with frequency roll-of. I’ve frequently come across the statement that damping factors > 10 is a minimum and >20 is best. Would there be any issues with respect to sound quality using damping factors between 10 and 20?

Thanks.
carlosaudio51
carlosaudio51 OP
9 posts
 
OK. What do you think is happening on my system? If I go DAC -> receiver I have clipping even at low volumes (20/100). If I add the SYS before the receiver and reduce the volume to about 3 o'clock, the clipping is gone.
atmasphere's avatar
atmasphere
11,676 posts
 
OK. What do you think is happening on my system? If I go DAC -> receiver I have clipping even at low volumes (20/100). If I add the SYS before the receiver and reduce the volume to about 3 o'clock, the clipping is gone.
Its pretty obvious that the receiver has active circuitry which can be overloaded before the volume control. The only good reason I can think of for a design character like this is that the receiver also has a DAC built-in, to which you are supposed to connect your digital source using a TOSLINK or HDMI connection.
carlosaudio51 OP
9 posts
 
Yes, it does have one. Granted, the Yamaha R-S202 does NOT have physical digital inputs (TOSLINK, coax, USB, etc.) but it DOES have Bluetooth, which means there's a DAC somewhere in there to convert the output of the Bluetooth receiver into analog. Even so, I have had the Bluetooth turned off on the receiver all this time. Interesting...

I don't have another receiver or DAC to do some testing to erik_squires' reply.

I know at this point on the post we're getting far into the weeds, considering that the solution is to have the SYS in the chain BUT I'm interested in the theory behind this so let me ask this:
-Erik_Squires said that most DACs output 2V thru RCA.
-Atmasphere said that the receiver likely has active circuitry (such as a DAC) built-on which can be overloaded.
-Most receivers I looked at have DACs built-in (either in the form of physical digital inputs or Bluetooth connectivity like mine).
-So is it best to use the receiver's built-in DAC to avoid overloading its analog inputs (when using external 2 Vrms DAC)? Or is this a situation of poor design choices (like Atmasphere suggested) probably because I have a cheap receiver ($129)? Are there better designed receivers that have built-in DACs but do NOT suffer from overloading the input, if an external DAC is the source?

Regardless, I've gotten what I needed out of this post. I understand start drying out since I'm asking stuff way beyond the scope of the original post.
atmasphere's avatar
atmasphere
11,676 posts
 
-Atmasphere said that the receiver likely has active circuitry (such as a DAC) built-on which can be overloaded.
I was not talking about a DAC- just that there is active circuitry prior to the volume control. If you were using the built-in DAC this wouldn't be happening.


Are there better designed receivers that have built-in DACs but do NOT suffer from overloading the input, if an external DAC is the source?
Of course! Price plays a role of course.
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