Quad 606 with 500mv input - how to use with with modern DAC? PC system

[greydea]

Looking for help to use a Quad 606 power amp. The input is 500 mv. It came with a Quad 44 (works fine with 500mv output) but the balance slider is creating noise in the left channel (will investigate later - seems like it can be bypassed or cleaned or fixed with heat from soldering iron).

My smsl su-1 is usually powering a Fosi v3. It all works fine. Use PC for volume control, trying to avoid a pre-amp unless its the way to go.

Question: the 2Vrms output of su-1 is too much for the Quad 606. What's the best way to deal with this?

-get a DAC with 500mv output?

-resistor voltage divider?

-preamp?

-??? adapter/part that converts 2Vrms to 500mv?

Thanks! It's hand me downs but potential upgrade...

 

[DVDdoug]

It's probably OK to use the software volume control but you might want to add an in-line attenuator which will allow you to use more volume-control range and limit how badly you can accidently blast your speakers & ears.

-12dB is 25%.

Technically, you do lose some resolution when lowering the volume digitally but it's usually not a big deal. Lowering the analog signal can also reduce your signal-to-noise ratio but with your setup, analog attenuation is probably theoretically-better.

 

[staticV3]

Question: the 2Vrms output of su-1 is too much for the Quad 606. What's the best way to deal with this?

The easiest:
Install Equalizer APO
Add a -12dB Preamp
Never use ASIO or Wasapi Exclusive for playback

The best:
Add a preamp or passive attenuator between DAC and 606

 

[dlaloum]

I had my local Quad guy give them a once over, and mod them for a higher V input....

I am unlikely to ever use them with the original Quad Pre's, so a more suitable 1V or 2V input level is easily achieved, and makes the 606's much easier to match with current prepro's

 

[greydea]

I’m back for more advice.

Have been using EAPO and -12db preamp. Works ok. It does prevent the powered subwoofer from working well. The sub out signal is too weak for the sub and good for the QUAD 606.

Tried cleaning balance slider and using various outputs of the QUAD 44. Still generating noise in the left channel. Going to move on.

Open to the analog inline -12db attenuators.

Wondering, what kind of preamp can I buy? Ideally, source is pc and preamp takes RCA from dac, or usb-c as input. Out is 500 mV RCA for the QUAD 606. And a sub out or or another RCA output.

Thanks for the info so far, it’s been very helpful!

 

[Ropeburn]

DACs with properly implemented volume control don't lose resolution in any relevant way, because it's 32bit and thus you only start losing data if you attenuate, say, 16bit input data more than 96dB. Irrelevant. The main limit is noise floor, but that's also not a practical problem as long as you don't hear it anyway - which is the case with all modern DACs on the quality level of the SU-1.

 

[dlaloum]

I’m back for more advice.

Have been using EAPO and -12db preamp. Works ok. It does prevent the powered subwoofer from working well. The sub out signal is too weak for the sub and good for the QUAD 606.

Tried cleaning balance slider and using various outputs of the QUAD 44. Still generating noise in the left channel. Going to move on.

Open to the analog inline -12db attenuators.

Wondering, what kind of preamp can I buy? Ideally, source is pc and preamp takes RCA from dac, or usb-c as input. Out is 500 mV RCA for the QUAD 606. And a sub out or or another RCA output.

Thanks for the info so far, it’s been very helpful!

I believe that changes to 4 resistors can raise the output V of the Quad 44 to current norms...

and for the input you can always choose different input modules

But first you would need to resolve the noise in the left channel... I would consider a Quad 44 worthy of a professional going over... (and there are various mods available too... )

 

[greydea]

Writing to update this thread. Added a nobsound volume control passive preamp between SMSL SU-1 DAC output and QUAD 606. With the nobsound volume control I can get the volume control range from the PC that I want. Bought an RCA splitter to split out mono left for the powered subwoofer. Seems to work well so far. Sounds much better with the Quad 606 vs the Fosi ZA3 (anecdotally).

 

[phoenixsong]

The easiest:
Install Equalizer APO
Add a -12dB Preamp
Never use ASIO or Wasapi Exclusive for playback

The best:
Add a preamp or passive attenuator between DAC and 606

Should this negative preamp be in the pre-mix or ost-mix stage in Equalizer APO itself?

 

[staticV3]

Should this negative preamp be in the pre-mix or ost-mix stage in Equalizer APO itself?

As long as it's the first block in the Configuration Editor, it shouldn't matter.

Though TBH, I didn't know that you could even select which mix your configuration goes into.