Benchmark DAC1 now available with USB

[EliasGwinn]

Quote:

Originally Posted by 8thdwarf /img/forum/go_quote.gif I would like the Dac-1 Pre to feed two unbalanced input stereo amplifiers without 'Y' adapters. Can the levels of the two outputs be adjusted close to each other once a balanced to unbalanced adapter is used? I hope this question is not stupid

This is a great question. The balanced and unbalanced outputs can be matched in calibrated mode using the calibration trim-pots, but if you are driving an amp directly, you will want to be in variable mode. The levels can be matched in variable mode.

However, the high-current output drivers on the DAC1 PRE are more then capable of driving two amp inputs via a Y-adapter. You will not lose any performance in this configuration. I would use this configuration if I were you.

Thanks,
Elias

 

[Scrith]

Quote:

Originally Posted by EliasGwinn /img/forum/go_quote.gif However, the high-current output drivers on the DAC1 PRE are more then capable of driving two amp inputs via a Y-adapter. You will not lose any performance in this configuration. I would use this configuration if I were you.

I can verify this statement. I used balanced Y-adapters to connect my DAC1 (2006 version) to two amps at the same time via the calibrated output (one was a Dynamight headphone amp, the other was a PS Audio GCC-250, both of which have volume controls, which made the usage of the calibrated mode possible).

I was concerned that I would lose some audio quality by sending the DAC1's output to two amps via splitters, so I conducted various careful tests (vs. a very expensive Cardas Golden Reference XLR cable!) and was able to enthusiastically conclude that there was no audible degradation of sound quality whatsoever (the test systems were DAC1 to SFT Dynamight to Qualia 010 headphones w/ Black Dragon cable and DAC1 to PS Audio GCC-250 to Totem Model 1 Signature speakers, with fancy cables throughout).

I'm not using this setup anymore, so my balanced splitter cables are available for a reasonable price if you are interested (these were custom made for me by DIYCable.com, I believe the type was known there as "Exodus Quadfield").

Here is a related thread here at Head-Fi.

 

[Matias]

Alright, you will hate me for this, but after an amp upgrade, I clearly hear that the focus on SPDIF is a lot better then optical, at least using a cheap Monster Lightspeed 100.

Any suggestions on a high-end optic cable?

 

[Bostonears]

Quote:

Originally Posted by Matias /img/forum/go_quote.gif Alright, you will hate me for this, but after an amp upgrade, I clearly hear that the focus on SPDIF is a lot better then optical, at least using a cheap Monster Lightspeed 100. Any suggestions on a high-end optic cable?

If you're going to use TOSLINK, I highly recommend an inexpensive glass fiber optic cable, such as this one
Amazon.com: Amphenol Ultra Series - Premium Optical Glass TOSLINK Cable - 6': Electronics

 

[indianbraker]

i would love to own this unit. im stuck with a zero dac for now though so ill be thankful for what i got.

 

[syfjhz22]

DAC-1 is a great DAC, I love to listen it.

 

[Matias]

Quote:

Originally Posted by Bostonears /img/forum/go_quote.gif If you're going to use TOSLINK, I highly recommend an inexpensive glass fiber optic cable, such as this one Amazon.com: Amphenol Ultra Series - Premium Optical Glass TOSLINK Cable - 6': Electronics

Very interesting.
Do you own one of these? Do they sound anything near SPDIF?

 

[Bostonears]

Quote:

Originally Posted by Matias /img/forum/go_quote.gif Do you own one of these?

Some factory (in China) churns out these low priced glass fiber optic cables for various brand names. I own three of them. I purchased mine at Sound Professionals, and they are often available on eBay (just search for "glass Toslink").

Quote:

Originally Posted by Matias /img/forum/go_quote.gif Do they sound anything near SPDIF?

SPDIF refers to the data protocol, not the cable itself, but I assume you want to know if they sound like coax digital cables. I have simultaneously hooked up my best coax digital cable (Kimber) and one of these glass fiber cables to a Squeezebox, fired up some tunes, and just switched the DAC back and forth between the coax and optical inputs. Over the years, I have tried this test with three different high quality DACs (Grace m902, Dodson DAC 263, and Benchmark DAC1 Pre) with dozens of songs, using both speakers and headphones, and in no case could I distinguish any difference between the coax and the glass fiber. With the Dodson DAC, the input switching was so seamless (absolutely no gaps, clicks, or other noises) that I wasn't sure the DAC was even switching inputs. I had to physically disconnect the cables during playback to be sure the DAC was actually using the corresponding input.

In short, I'm sold on these cheap glass optical cables.

 

[Matias]

Thanks, Bostonears. You are right about that SPDIF: it's the same protocol on both cables, be it coax or optic. My mistake.

Very interesting. I will search some of those, let's see.
Thank you very much.

Did you try the fuses on the DAC1? Now those did wonders to it.

 

[8thdwarf]

Elias, thanks for the help.


Scrith thanks for the help, offer and link. I've some decisions 1st so I'll save your info.

 

[Wavelength]

Quote:

Originally Posted by Bostonears /img/forum/go_quote.gif Some factory (in China) churns out these low priced glass fiber optic cables for various brand names. I own three of them. I purchased mine at Sound Professionals, and they are often available on eBay (just search for "glass Toslink"). SPDIF refers to the data protocol, not the cable itself, but I assume you want to know if they sound like coax digital cables. I have simultaneously hooked up my best coax digital cable (Kimber) and one of these glass fiber cables to a Squeezebox, fired up some tunes, and just switched the DAC back and forth between the coax and optical inputs. Over the years, I have tried this test with three different high quality DACs (Grace m902, Dodson DAC 263, and Benchmark DAC1 Pre) with dozens of songs, using both speakers and headphones, and in no case could I distinguish any difference between the coax and the glass fiber. With the Dodson DAC, the input switching was so seamless (absolutely no gaps, clicks, or other noises) that I wasn't sure the DAC was even switching inputs. I had to physically disconnect the cables during playback to be sure the DAC was actually using the corresponding input. In short, I'm sold on these cheap glass optical cables.

Boston,

Remember that with SPDIF you are not only looking at data but the clock riding on the back of the data(Biphase). The best way to test the spdif interface is too monitor the PLL on the receiver side as well as the error indicators to determine which interface, cable etc... works best. I have a widget around here somewhere that has an AKM, Cirrus/Crystal and one of those TI receivers and allot of bond out testing stuff that I made years ago too test this.

By looking at the PLL you can see how well the receiver is working at realigning the output clock Master Clock to the input stream. Basically the receivers look at the framing information to determine the Master Clock output. The Framing output of the pll is multiplied by 256 and the Master Clock is then outputed. From there the Bit Clock and Word Clock are derived. You can also put a spectral analyzer on the Master Clock and look for jitter another indication of how well the cable and interface are working.

In my experience glass/plastic has never really done SPDIF justice, nor has AES/EBU.

The best interface I found is BNC on both sides and using a truely 75 ohm cable. Even there the best I have found is the Nirvana Audio T2.

Guys an RCA connector can never be 75 ohms. Anyone telling you they have rewritten the physics books and created a truely 75 ohm rca cable is only kidding themselves. Not too say these don't work... they just don't work as well.

If you want to run longer SPDIF cables then I do agree that glass/plastic or toslink may be your best bet. The galvanic isolation will help the receiver side a ton.

Thanks
Gordon

 

[iNiGFx]

yeah, i wanna to sell my DA10 to get the DAC1U

 

[EliasGwinn]

Quote:

Originally Posted by iNiGFx /img/forum/go_quote.gif yeah, i wanna to sell my DA10 to get the DAC1U

Welcome...

 

[DigiPhx]

Quote:

Originally Posted by EliasGwinn /img/forum/go_quote.gif Welcome...

Welcome too,
I'm planning to get DAC1U in this month, it will connect to my Dyna Air6 for my reference. hehe

 

[doctorcilantro]

When the XLR output is used but as unbalanced (w/ 3rd pin floated), does the DAC1 still output +4DBv ? I'm thinking of using the RCA unbalanced out as well and it seems that with the attenuator at 0 for XLR output the RCA should be at -10dbu when the XLR is calibrated to +4dbv at 0dbfs.

Here are some measurements:

DAC to tube preamp (0dbfs+ sine wave at -20db applied by Replay Gain in J. River playback software): .850v

Pre to monoblock:

Pre @ 9o'clock = 40mv
Pre @ 12o'clock = 297mv
Pre @ 2o'clock = .562v
Pre @ 3o'clock = .935v

I guess I'm trying to figure out what is happening at my RCA outs right now with the above measurements (given that I am using unbalanced XLR).

thanks!
DC