[EliasGwinn]

Hey folks,

To those who question the integrity of this thread, I'd like to say, "Great!" Questioning manufacturers is a great thing to do, and I encourage you to do so, not only to myself and Benchmark, but all the other manufacturers as well. Audio equipment costs too much to accept claims without analyzing, scrutinizing, and questioning them. And I believe it is the designers responsibility to explain themselves in clear, concise, objective terms.

I do not, and will not, make subjective claims about the sonic nature of our products, because it would be undeniably biased. It would turn this thread into 'marketing B.S.', and I don't want that. I won't let that happen. The sonic nature of the DAC1 will speak for itself, either with trail-based listening, or through the current owners. We offer a 30-day trial period because we know that a perspective customer needs to hear the product to know for sure if it will suit them.

The information I present on this thread is strictly based on objective, measurable facts. I am not a 'sales person'. I am an electrical engineer (mainly R&D), and I double as technical support.

There are three main reasons we encourage this type of disussion:

1- Customers need to know how to make the most of their audio setup. Without doing hundreds of hours of research and testing, it is impossible to know the best settings for all the devices in the audio chain. We have done that testing, and we can provide that information to you.

2 - It provides feedback to us, which is immensely important for designing (or correcting) products to better suit the users. The headphone volume is a perfect example. Without hearing the users tell us that the volume is too loud, we would not have known any different. However, with this information, we can take action and re-adjust the design for a lower volume. The result is a better product, which is better for the users as well as us.

3 - There is way too much 'snake oil' in this industry. People are being taken advantage of by manufacturers who make outrages claims, exploiting customers simply because they can't know any better without a background in electronic design and thousands of dollars of testing equipment. We pride ourselves in making products that are very 'real'. They have proven results, and can stand up to the scrutiny of the most stringent of tests. They are built to be transparent, faithful, and completely accurate. They are not built to an aesthetic. This forum provides us the opportunity to objectively explain how every component works to make the product exactly what it is. We want to debunk any mysteries or unknowns related to audio electronics.

Hope that helps explain things!!

Thanks,
Elias

 

[chesebert]

IIRC, DAC1 uses a switching PS. could you do me a favor and run a FFT on the DC output of that PS. I would like to know the harmonic content of the DC noise and also their respective amplitudes.

My next question is why switching vs linear, which is easier to design.

while you are doing the FFT for DC output, would you also run a FFT on the Vo of the analog stage? I don't remember seeing this graph published by stereophile.

 

[EliasGwinn]

Quote:

Originally Posted by chesebert /img/forum/go_quote.gif IIRC, DAC1 uses a switching PS. could you do me a favor and run a FFT on the DC output of that PS. I would like to know the harmonic content of the DC noise and also their respective amplitudes. My next question is why switching vs linear, which is easier to design. while you are doing the FFT for DC output, would you also run a FFT on the Vo of the analog stage? I don't remember seeing this graph published by stereophile.

Chesebert,

Thanks for the questions.

The DAC1 does not have a switching power supply, it has a linear power supply. We could run an FFT of the DC output if you like.

Another interesting fact about the power supply is, when the DAC1 was in development, we wanted to test how immune the audio circuit was to noise on the power supply. So we injected high levels of audio-band signal onto the DC rails to determine if there was any crosstalk. The maximum power supply noise in the audio circuit was less then -126 dB (as posted in the specs), even with noise artificially imposed onto the supply rails.

As for running "a FFT on the Vo of the analog stage?", do you mean a Frequency Response plot, or an idle-channel noise FFT? These are both available in our manual, and I would be glad to post them here independently. If I'm misunderstanding what you meant, could you please clarify?

Thanks,
Elias

 

[chesebert]

Quote:

Originally Posted by EliasGwinn /img/forum/go_quote.gif Chesebert, Thanks for the questions. The DAC1 does not have a switching power supply, it has a linear power supply. We could run an FFT of the DC output if you like. Another interesting fact about the power supply is, when the DAC1 was in development, we wanted to test how immune the audio circuit was to noise on the power supply. So we injected high levels of audio-band signal onto the DC rails to determine if there was any crosstalk. The maximum power supply noise in the audio circuit was less then -126 dB (as posted in the specs), even with noise artificially imposed onto the supply rails. As for running "a FFT on the Vo of the analog stage?", do you mean a Frequency Response plot, or an idle-channel noise FFT? These are both available in our manual, and I would be glad to post them here independently. If I'm misunderstanding what you meant, could you please clarify? Thanks, Elias

I am sorry, I should have been more clear. I mean a FFT of the 1Khz on the Vo. I am curious to see the harmonic content and their relative amplitudes.

Thanks

 

[Jetlag]

Quote:

Originally Posted by EliasGwinn /img/forum/go_quote.gif We recommend (and use) Canare StarQuad analog balanced cables with Neutrik connectors. They are both very high quality, sonically and mechanically, and not over-priced. We have our cables built by Have, Inc (www.haveinc.com)

Exactly what I am using:

Although I intended to listen to music using USB from my newly built computer via FLAC + Foobar, I changed my mind in the end. My chain is FLAC (CDs ripped using EAC + AccurateRip plugin) stored on my Infrant NV running Slimserver > gigabit ethernet > SB3 (digital out at fixed volume) > SPDIF > DAC1 USB > XLR cables above > Paradigm Active Ref Studio 20s.

To keep computer sounds separate from my audio chain I use my sound card connected to my LC-32GP1U via 1/8" stereo cable. This way the Active 20s play music, and the LCD speakers produce all sound from my PC.

I am a former DAC1 classic owner and love the sound due to it being as neutral as anything I have heard. I don't want coloration, warming, softening, etc., and none of my CDs had any layers of grunge or veils that required removing. IMOHO the DAC1 is very accurate and effectively converts the digital signal into analog without inflicting any harm or its own personality onto the music. What goes in is what comes out which is exactly what I want, I want to hear what the musician(s) & their chosen recording engineer intended me to hear. I squeezed my setup together for this photo, but it gives you an idea of how much I enjoy working in my home office now.

 

[Lord Chaos]

The reason I mentioned the volume characteristics of the Squeezebox is that I was very surprised to find that it varied the digital output to my DAC1. I thought digital was always full-honk. Turning down the Squeezebox volume reduces both the unit's headphone amp (wimpy and noisy) and the S/PDIF level.

The DAC1 USB has internal jumpers you can set to reduce the gain in the headphone amp by 10dB. The "regular" DAC1 doesn't have these.

Both units have excellent sound quality, better than any other digital component I've heard in many years of using audio equipment. Pipe organ music, which I find unlistenable on most systems due to the graininess, is smooth and musical from the DAC1. Everything else simply sounds like music, not machinery. The quality of the listening experience is entirely dependent upon the recording quality: whatever is there, is what I get from the DAC1.

I'm not the ultimate tweaker. I'm looking for "good enough." In this case, good enough is outstanding. My standard is live unamplified music.

 

[Jetlag]

Quote:

Originally Posted by Lord Chaos /img/forum/go_quote.gif The reason I mentioned the volume characteristics of the Squeezebox is that I was very surprised to find that it varied the digital output to my DAC1. I thought digital was always full-honk. Turning down the Squeezebox volume reduces both the unit's headphone amp (wimpy and noisy) and the S/PDIF level.

To keep this from happening open SS, click on "player settings" and then use the drop down menu at the top and select "audio". 2/3 down the page you'll see a selection for "Digital Volume Control". Use the drop down menu and select "digital output volume is fixed" and click the "change" button. Done!

(Not trying to hijack this great thread BTW)

 

[pianomav]

Quote:

Originally Posted by Jetlag /img/forum/go_quote.gif Exactly what I am using: Although I intended to listen to music using USB from my newly built computer via FLAC + Foobar, I changed my mind in the end. My chain is FLAC (CDs ripped using EAC + AccurateRip plugin) stored on my Infrant NV running Slimserver > gigabit ethernet > SB3 (digital out at fixed volume) > SPDIF > DAC1 USB > XLR cables above > Paradigm Active Ref Studio 20s. To keep computer sounds separate from my audio chain I use my sound card connected to my LC-32GP1U via 1/8" stereo cable. This way the Active 20s play music, and the LCD speakers produce all sound from my PC. I am a former DAC1 classic owner and love the sound due to it being as neutral as anything I have heard. I don't want coloration, warming, softening, etc., and none of my CDs had any layers of grunge or veils that required removing. IMOHO the DAC1 is very accurate and effectively converts the digital signal into analog without inflicting any harm or its own personality onto the music. What goes in is what comes out which is exactly what I want, I want to hear what the musician(s) & their chosen recording engineer intended me to hear. I squeezed my setup together for this photo, but it gives you an idea of how much I enjoy working in my home office now.

Jetlag,

What's the part ID for those xlr cable? Is this the HAVEFLEX STARQUAD CBL XLRM-XLRF ? I'm trying to get a pair myself... thanks...

 

[MusicFirst]

Very nice Aquos, Jetlag. I have the 32" 1080p. What size is yours?

 

[Jetlag]

Mine are a slightly older version of the HAVEFLEX STARQUAD CBL XLRM-XLRF 6' BLACK, Part ID: 201000-06BLA. Now they are made with nickel shells and silver contact pins vs my black shells and gold pins. You can still get the black ones at B&H Photo, part number CAXMXF6 but I prefer the look and lower cost of the newer ones. (or you could always get a 1 meter pair of Stealth Indras for just $7475 for balanced XLR.)

Quote:

Originally Posted by MusicFirst /img/forum/go_quote.gif Very nice Aquos, Jetlag. I have the 32" 1080p. What size is yours?

LC-32GP1U (32" 1080P)

OK, now back to discussing the DAC1 USB (and please pardon the interruption)

 

[pianomav]

thnx Jetlag...

 

[EliasGwinn]

Quote:

Originally Posted by infinitesymphony /img/forum/go_quote.gif I have a question about DAC1 differences... I've heard from several people that during the course of production, the DAC1 has received some significant updates without version designations. It appears that the USB version has the most changes with regard to the original design. Can anyone comment on any or all of the changes that have taken place? I apologize if this has been answered earlier in the thread.

The early (pre May 2004) DAC1's had a few things that we've since upgraded. Those things are:

1 - Maximum input sample rate: 96 kHz. Upgraded to >192 kHz

2 - Unbalanced outputs had output impedance of 1.25k. This was to prevent distortion when the R & L were "Y'd" together for forced mono. We've since lowered the output impedance to 30 ohms.

3 - Continuous volume pot was replaced with detented volume pot

4 - Trim resistor added to eliminate DC offset at volume pot

These changes (except the 192kHz) were made based on field experience and user feedback. The circuit board revision number was changed upon each revision.

Thanks,
Elias

 

[EliasGwinn]

Quote:

Originally Posted by thomaspf /img/forum/go_quote.gif I appreciate your enthusiasm but I am unaware of any engineering Benchmark has done on the USB part except for interfacing to the digital output. The chip is a standard TI chip and the firmware comes from Centrance. Maybe Centrance has done some engineering on Benchmark's behalf. Some of the claims made on this thread about this solution are to quote you again 'marketing BS'. The DAC1 is a very good DAC but how can they claim that their device changes the behavior of how Windows works. I looked at a bunch of USB audio devices in detail including the DAC1 USB and the only detail in how their USB audio device looks different to the system is that it annouces itself as only supporting 24bit PCM. That does not make the system suddenly send bit perfect data to it. Cheers Thomas

Thomas,

The firmware for the DAC1 USB was developed jointly between Benchmark and Centrance. The majority of the code was initially written by Centrance, and the majority of the trouble-shooting of the code was done by Benchmark.

The DAC1 USB firmware does not change how Windows operates. The firmware simply provides a non-obstructive path to stream bit-transparent data.

I have personally ran tests to verify bit-transparency. These tests were developed by Audio Precision, the leader in audio testing equipment and software. The Audio Precision has a predetermined bit-stream. We made a .wav file of that bit stream and played it through various common media players. The audio was streamed through the USB port (using USBaudio.sys), converted to PCM, and sent back into the Audio Precision. The Audio Precision compared this returned bit-stream with the initial predetermined-bit stream. If any bits had changed, the Audio Precision would report an error. If there are no bits changed, the Audio Precision reports no errors.

This is not a distortion test, or an averaging function, or an FFT. This test checks the bit-stream, bit for bit.

Thanks,
Elias

 

[EliasGwinn]

Quote:

Originally Posted by sangel /img/forum/go_quote.gif Hello Elias, Here, http://www.benchmarkmedia.com/dac1/dac1-usb_par.pdf i.e. a bench test review, I have found an issue releted to DAC1 usb, output impedance on XLR's. The reviewer found - measured - an output impedance - on XLR - of 133 Ohms. Now, considering that the output impedance - from the specs - is 60 Ohms, (i.e. 30 + 30 Ohms per +/- leg ), then what is the real status for this subject... This is very important...as you may realize.. Thanks in advance. Best Sangel ps. As far as I now the DAC1 output impedance remains stable - unchanged (for fix and variable output modes on BOTH RCA & XLR)

Sangel

The impedance mentioned in the review was measured with the 20 dB attenuators activated. The output impedance of the DAC1 without output attenuation is 60 ohms.

Thanks,
Elias

 

[infinitesymphony]

Quote:

Originally Posted by EliasGwinn /img/forum/go_quote.gif The early (pre May 2004) DAC1's had a few things that we've since upgraded. Those things are...

Thanks! Those all sound like great updates. I've been craving a DAC1 for use as a DAC/preamplifier with balanced studio monitors, and reading this thread hasn't made it any easier on my wallet.

Now, to decide between the regular or the USB version...