Benchmark DAC1 configuration

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Benchmark DAC1 configuration

Postby darrenyeats » Wed Jan 18, 2017 7:39 pm

I've posted this in the past, and a few have been in touch about it - my DAC1 configuration guide. I've recently added an important new step (8).
http://www.pinkfishmedia.net/forum/show ... p?t=137152

Upsampling to 110.6kHz in software (SoX in VHQ mode plugged into Squeezebox streaming) seems to have given a useful uplift in performance. In addition to my other advice, I view this as a tasty cherry on the cake that must be tried - but I recommend all other relevant steps be taken too!

This is the last of the tweaks to the Touch/DAC1 front end I think. Also there have been numerous tweaks to acoustics, which is always the place to start.

I have to say the sound of the whole system has reached a level that I've desired for a long time. One live recording which I heard rendered absolutely brilliantly by Linkwitz Orions elsewhere, at last came out just as good on the 50s. I was happy!
Last edited by darrenyeats on Sun Feb 12, 2017 10:34 am, edited 3 times in total.

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Re: Benchmark DAC1 configuration

Postby MattSPL » Fri Jan 20, 2017 1:14 am

Thanks for the update, some of these tweaks apply to my Dac too.
Sony BDP-S790 > Matrix Quattro Dac > Digidesign RM2's with SB Acoustics drivers > DIY Dayton Audio UM18-22 Sub

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Re: Benchmark DAC1 configuration

Postby darrenyeats » Fri Jan 20, 2017 7:27 pm

Hi Matt,
Ideally you'd resample to 192kHz for the Matrix Quattro. Otherwise the same options as in (8) on my config link, I think. It's worth trying but I think the outcome of any comparison will depend on the quality of the native filtering within the DAC in question. Admittedly, the DAC1 chip set is "old" now; not sure how newer chip sets will fare.

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Re: Benchmark DAC1 configuration

Postby MattSPL » Fri Jan 20, 2017 10:50 pm

Hi Darren,

I'd be interested to compare a new Dac to mine, just to see what a newer, better Dac can do.

Cheers
Matt
Sony BDP-S790 > Matrix Quattro Dac > Digidesign RM2's with SB Acoustics drivers > DIY Dayton Audio UM18-22 Sub

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Re: Benchmark DAC1 configuration

Postby darrenyeats » Sat Jan 21, 2017 11:17 am

Yeah this has also got me less skeptical about that. I have OCD though, and for DAC/pre duty, via XLR, I want something with 2V output or less. And low output impedance. Like I have now. The choice is rather limited!
* Benchmark. I'm not a fan of the output attenuators and they worsen output impedance - and AFAIK only the DAC1 had calibration trimmers, so DAC2/3 are out.
* Weiss.
* dCS.

What annoys me about 4V output is that I spend £xxxx pounds for 10dB more dynamic range/lower noise, and then piss away 6dB! I can't have that.

If you have a separate preamp, then much of the above is moot, I think.

As I wrote, OCD.

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Re: Benchmark DAC1 configuration

Postby MattSPL » Sat Jan 21, 2017 12:14 pm

My Matrix Quattro has the internal output attenuators like the Dac1. I have found the best results running the Quattro at 0db and attenuating the input on my active speakers. This allows me to use more of the volume dial and get more voltage out the rca outputs of the Quattro to feed the subwoofer.
I heard of people missing the internal attenuators of the Dac1 to remove that part of the circuit.
Sony BDP-S790 > Matrix Quattro Dac > Digidesign RM2's with SB Acoustics drivers > DIY Dayton Audio UM18-22 Sub

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Re: Benchmark DAC1 configuration

Postby linger63 » Sat Jan 21, 2017 12:53 pm

Hi Darren,

Read your Benchmark DAC1 configuration guide with great interest.
I own a DAC2 which sounds great to me but I am wondering if you have any worthwhile tips for optimising it's SQ.

I currently run at XLR level straight to ATC SCM70 ASL's (non adjustable input sensitivity) with the XLR attenuator pads set at -20dB.
I do have a separate pre amp (with 2 ohm output impedance) that I can reintroduce to the system.

It was removed when I installed an OPPO 105 and connected it at XLR level direct.
Even though I was now using digital attenuation (couldn't go above 60 on the VC though as it got too loud) my friends and I still preferred the resulting SQ.............simply sounded clearer and more detailed which we attributed to a shorter and more direct signal path and by having one less component and one less pair of I/C's (Kimber Hero's) in the system.

When the Benchmark DAC2 arrived I simply switched to using the OPPO as a transport........AFAIK the OPPO has NO attenuation for it's digital outs.......The Benchmark DAC2 VC only gets too loud after 12 o clock.

I do know that Benchmark recommend direct XLR connection as optimal for SQ.

My separate pre amp is of very good quality but does not offer XLR connections.
No PC in the system

Also happy to experiment but may not have correct cable configurations and also using different Brands would have an effect on results.
Please advise potential scenarios regardless of cable configuration and I will attempt to score as necessary.


TIA

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Re: Benchmark DAC1 configuration

Postby darrenyeats » Sat Jan 21, 2017 3:34 pm

Linger,
Below are the 8 steps (see link in post 1) but "translated" for a DAC2.
- (1) (2) (3) The XLR output attenuators ... hmm! I wouldn't remove the -20dB pad, because you're going to lose 20dB of SNR from the the DAC2's digital volume control. And the calibration (bypass) mode in the DAC2 is a digital level, it doesn't change the physical gain. I encourage you to try the RCA outputs, if the interconnect run is not too long, with RCA-to-XLR cables. The DAC2's RCA outputs are 2VRMS naturally - no output attenuators and before digital attenuation. You'll lose the common mode rejection of XLR but as long as you run the interconnect away from power cables, I think there will really be no impact for a short run. Also, the output impedance is actually even better via RCA than the XLRs even without attenuators!
- (4) Ignore this step since the DAC2 has a digital volume control for its digital inputs.
- (6) (7) Do these.
- (8) You will need a PC to try this. The hopeful news is the DAC2 chip set is more modern than the DAC1: there might be little, or nothing, to gain from this step with a DAC2, though I have no way to check.

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Re: Benchmark DAC1 configuration

Postby darrenyeats » Sun Jan 22, 2017 12:12 pm

I've added the following note
--
Benchmark state in the notes for Figure 10 here https://benchmarkmedia.com/blogs/applic ... asurements "the DAC1 has slightly more ripple in the frequency response. ... This difference is due to the improved digital filters in the DAC2".

Neither Benchmark nor I imply the FR ripple per se is audible, just that it's a measurable symptom of errors in the digital filtering.

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Re: Benchmark DAC1 configuration

Postby darrenyeats » Sun Feb 12, 2017 10:20 am


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