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 Post subject: A/B testing a DAC
PostPosted: Sat Nov 18, 2017 8:45 pm 
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Joined: Fri Jan 06, 2017 11:37 pm
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Location: Victoria, BC, CA
I hope to be taking possession of a Bryston BDA-1 DAC in the next week or so and would like to do some A/B testing of it against the DAC in my CD player (an Arcam CD72).

My plan is to connect the CD player's analog output to my pre-amp input. I would additionally hook the CD player's coaxial output to the BDA-1 which would itself be connected to the pre-amp. Then, by switching inputs on the pre-amp, I'd instantly hear the difference.

Will this work? (The big question I have is will the CD player power both outputs simultaneously?) Is there any reason why this is a bad idea?

Thanks!


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 Post subject: Re: A/B testing a DAC
PostPosted: Sat Nov 18, 2017 8:56 pm 
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Location: Calgary, AB, CA
aleknevicus wrote:
I hope to be taking possession of a Bryston BDA-1 DAC in the next week or so and would like to do some A/B testing of it against the DAC in my CD player (an Arcam CD72).

My plan is to connect the CD player's analog output to my pre-amp input. I would additionally hook the CD player's coaxial output to the BDA-1 which would itself be connected to the pre-amp. Then, by switching inputs on the pre-amp, I'd instantly hear the difference.

Will this work? (The big question I have is will the CD player power both outputs simultaneously?) Is there any reason why this is a bad idea?

Thanks!


Yes, this will work perfectly for what you're doing. I do this all the time comparing the DAC on my Audio Research CD player against a stand-alone DAC. To make it an even playing field you need to make sure that you're using similar brand and quality of interconnects and power cord for both units. In so far I haven't heard a stand-alone DAC that will beat the DAC on my Audio Research yet.

However, methinks, as good as your Arcam cd player's DAC is the Bryston DAC will beat it hands down.


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 Post subject: Re: A/B testing a DAC
PostPosted: Sat Nov 18, 2017 11:53 pm 
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Location: Victoria, BC, CA
Thanks! I'm definitely hopeful that the Bryston will offer an improvement.


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 Post subject: Re: A/B testing a DAC
PostPosted: Sun Nov 19, 2017 3:24 am 
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Location: Hubley, NS, CA
I’d be interested in hearing the opinions on the BDA-1 as I’m thinking of using one on my BDP-1 instead of the DAC built in to my Anthem AVM60.

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 Post subject: Re: A/B testing a DAC
PostPosted: Sun Nov 19, 2017 5:02 am 
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Location: Halifax, NS, CA
A critical aspect to A/B testing is volume matching. The analog output voltage of your CD player may not match the output of the BDA, which will change the volume output to you. Even if the specs say they have the same output voltage, I have found differences. A 1 dB difference output from your speakers can make an impact on something sounding better or worse (louder usually sounding better). If you can instantaneously switch between sources, hopefully you can detect this fairly easily. The pain however is if they don't match, and you're not sure by how much, trying to adjust your preamp each time to match them (up for one, then down for the other). That can make A/B testing quite a bit trickier.

Ideally you would have an SPL meter and a test tone (ideally pink noise) you could play through each and then measure the volume output on the SPL meter from the same location each time. I actually use an app on my Android phone that acts as an SPL meter, which works pretty well. Then you need to try to make a reliable volume change on your preamp each time to match the dB levels. Depending on your preamp, that can be easier said than done however.

Hopefully the outputs from your CD player and BDA will match so you don't have to deal with this because it can be a pain.


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 Post subject: Re: A/B testing a DAC
PostPosted: Sun Nov 19, 2017 9:42 am 
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Location: Calgary, AB, CA
rlowe wrote:
A critical aspect to A/B testing is volume matching. The analog output voltage of your CD player may not match the output of the BDA, which will change the volume output to you. Even if the specs say they have the same output voltage, I have found differences. A 1 dB difference output from your speakers can make an impact on something sounding better or worse (louder usually sounding better). If you can instantaneously switch between sources, hopefully you can detect this fairly easily. The pain however is if they don't match, and you're not sure by how much, trying to adjust your preamp each time to match them (up for one, then down for the other). That can make A/B testing quite a bit trickier.

Ideally you would have an SPL meter and a test tone (ideally pink noise) you could play through each and then measure the volume output on the SPL meter from the same location each time. I actually use an app on my Android phone that acts as an SPL meter, which works pretty well. Then you need to try to make a reliable volume change on your preamp each time to match the dB levels. Depending on your preamp, that can be easier said than done however.

Hopefully the outputs from your CD player and BDA will match so you don't have to deal with this because it can be a pain.


I suppose it was easy for me to do the A/B testing as my pre amp has an "Input Level Trim" function. This function enables me to select an input offset to match the volume to any particular input. The options are: +/-6 dB, in 1 dB increments.


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 Post subject: Re: A/B testing a DAC
PostPosted: Sun Nov 19, 2017 9:56 am 
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Location: Halifax, NS, CA
tube54 wrote:
I suppose it was easy for me to do the A/B testing as my pre amp has an "Input Level Trim" function. This function enables me to select an input offset to match the volume to any particular input. The options are: +/-6 dB, in 1 dB increments.


Oh heck yeah that would make things way easier to essentially have a volume memory on each input. Wish my preamp had that.


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 Post subject: Re: A/B testing a DAC
PostPosted: Sun Nov 19, 2017 10:05 am 
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Location: Calgary, AB, CA
rlowe wrote:
tube54 wrote:
I suppose it was easy for me to do the A/B testing as my pre amp has an "Input Level Trim" function. This function enables me to select an input offset to match the volume to any particular input. The options are: +/-6 dB, in 1 dB increments.


Oh heck yeah that would make things way easier to essentially have a volume memory on each input. Wish my preamp had that.


Yup! I'm using the Krell Evolution 202 preamp it's not the best preamp out there but it does the job for me and then some
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 Post subject: Re: A/B testing a DAC
PostPosted: Sun Nov 19, 2017 10:42 am 
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IME volume matching is not critical. This is because for each recording there is a given volume level at which it is best heard. Some you have to turn down, others turn up. If you match volume for all the test pieces, you will very likely be hearing one or more of them at the wrong level, i. e. a level which does not do justice to the musical experience.

As for fast switching from A to B, this may be useful if you are able to label (in words) your experience very swiftly, then free up your mind for the next impression. You cannot go back later and hunt for the right description. If you can label and file fast enough, you may take away something worthwhile, but it is tiring.

However it has to be said that listening to music for pleasure is not done with fast A/B switching. Such switching may help to isolate small differences between units whose sound is otherwise very similar, but again, you have to be able to categorize really fast.

But when the differences between two pieces of gear are easily perceived, there is no point in fast A/B switching. One is better off listening over time to each, and then setting up a session in which the same selections are played, first on one unit, then on the other, in a system which is otherwise stable. One listens to the music, makes notes, and draws conclusions afterwards about the musical value of what one has heard.

It is fun and very useful to do this with a willing friend or partner.


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 Post subject: Re: A/B testing a DAC
PostPosted: Sun Nov 19, 2017 11:11 am 
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Toby wrote:
IME volume matching is not critical. This is because for each recording there is a given volume level at which it is best heard. Some you have to turn down, others turn up. If you match volume for all the test pieces, you will very likely be hearing one or more of them at the wrong level, i. e. a level which does not do justice to the musical experience.

As for fast switching from A to B, this may be useful if you are able to label (in words) your experience very swiftly, then free up your mind for the next impression. You cannot go back later and hunt for the right description. If you can label and file fast enough, you may take away something worthwhile, but it is tiring.

However it has to be said that listening to music for pleasure is not done with fast A/B switching. Such switching may help to isolate small differences between units whose sound is otherwise very similar, but again, you have to be able to categorize really fast.

But when the differences between two pieces of gear are easily perceived, there is no point in fast A/B switching. One is better off listening over time to each, and then setting up a session in which the same selections are played, first on one unit, then on the other, in a system which is otherwise stable. One listens to the music, makes notes, and draws conclusions afterwards about the musical value of what one has heard.

It is fun and very useful to do this with a willing friend or partner.


Perhaps...but in my case, volume matching for both inputs were very critical. For example, once I matched all the cables brand quality for both units and the volume for both inputs then I proceed to listen to my favorite and familiar recordings. Familiar recordings that were recorded very well with fewer electronics manipulation during the process of downmixing into a stereo track. Then I focus on the bass bloom and transient, instrument and vocals natural timbre and harmonics and whatnot. Whichever unit sounded closest to the live sound wins it for me. BTW, my friend's Krell Cipher SACD player that I compared with my Audio Research using the same songs on PCM format beat my Audio Research hands down except in the full-bodied sound category.


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 Post subject: Re: A/B testing a DAC
PostPosted: Sun Nov 19, 2017 12:00 pm 
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Location: Delta, BC, CA
That looks like a sweet system you have there!! Very nice combinations of gear... clean looking and excellent quality.... good choices!


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 Post subject: Re: A/B testing a DAC
PostPosted: Sun Nov 19, 2017 12:33 pm 
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Tutone wrote:
That looks like a sweet system you have there!! Very nice combinations of gear... clean looking and excellent quality.... good choices!


Thanks. my system comprises a hodgepodge of equipment as I'm combining the old technology with the new. I have learned a long time ago that when putting equipment together the synergy factor does matter.


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 Post subject: Re: A/B testing a DAC
PostPosted: Sun Nov 19, 2017 1:37 pm 
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Location: Halifax, NS, CA
Toby wrote:
IME volume matching is not critical. This is because for each recording there is a given volume level at which it is best heard. Some you have to turn down, others turn up. If you match volume for all the test pieces, you will very likely be hearing one or more of them at the wrong level, i. e. a level which does not do justice to the musical experience.

As for fast switching from A to B, this may be useful if you are able to label (in words) your experience very swiftly, then free up your mind for the next impression. You cannot go back later and hunt for the right description. If you can label and file fast enough, you may take away something worthwhile, but it is tiring.

However it has to be said that listening to music for pleasure is not done with fast A/B switching. Such switching may help to isolate small differences between units whose sound is otherwise very similar, but again, you have to be able to categorize really fast.

But when the differences between two pieces of gear are easily perceived, there is no point in fast A/B switching. One is better off listening over time to each, and then setting up a session in which the same selections are played, first on one unit, then on the other, in a system which is otherwise stable. One listens to the music, makes notes, and draws conclusions afterwards about the musical value of what one has heard.

It is fun and very useful to do this with a willing friend or partner.


WRT volume matching, I was referring to fast switching A/B testing of the same tracks, or even specific passages. Volume matching is critical for this otherwise not a true A/B test and it will bias your result.

For longer term listening sessions across various tracks and then switching to another component and listening again for a decent amount of time, or across various tracks, I agree volume matching is not critical. I also agree that longer term listening and then swapping is a very valuable exercise and may be just as important or more important than fast switching because DACs don't tend to differ that significantly where the differences are immediately obvious by fast switching.


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 Post subject: Re: A/B testing a DAC
PostPosted: Sun Nov 19, 2017 4:45 pm 
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Joined: Fri Jun 05, 2015 9:02 am
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Location: Toronto, ON, CA
aleknevicus wrote:
I hope to be taking possession of a Bryston BDA-1 DAC in the next week or so and would like to do some A/B testing of it against the DAC in my CD player (an Arcam CD72).

My plan is to connect the CD player's analog output to my pre-amp input. I would additionally hook the CD player's coaxial output to the BDA-1 which would itself be connected to the pre-amp. Then, by switching inputs on the pre-amp, I'd instantly hear the difference.

Will this work? (The big question I have is will the CD player power both outputs simultaneously?) Is there any reason why this is a bad idea?

Thanks!


This will work and I am 100% convinced you will hear a difference for the better. I used this CD player with a PS Audio DAC with great results.
Happy testing!
V


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