[Covenant]

I'm sorry if this question has been asked already, i read through the first 25pgs before i couldnt absorb information any longer

I am considering purchasing a DAC1 for use in a balanced system, running the XLR outputs to a balanced B22 amplifier. One thing that AMB specifically cautions against with the B22 is to ensure that there is no DC offset at the source, as the amp design does not handle this well.

Mr Elias, does the DAC1 (USB or non-USB) measure any DC offset at its outputs, either unbalanced or balanced?

Thank you again for your time and patience. Its awesome to see a product in the (often snake-oil laden) audiophile industry so well backed up by the engineers who designed it, kudos to you

 

[riverlethe]

Quote:

Originally Posted by little-endian /img/forum/go_quote.gif Well, actually it's not a big problem at all (at least I presume that no harm to the hardware is done by this interference). I was just interested if the DAC1 would "react" to this. I always thought that just radio receivers were especially prone to this by nature.

I've heard cell phone noises if I had it near my headphone cable. There was even a study recently saying that sleeping too close to your cell phone can disrupt your sleep cycle...

 

[Covenant]

Or if Elias isnt available to post, have any of the DIYers checked the DAC1's outputs for DC offset?

 

[little-endian]

Quote:

Originally Posted by riverlethe /img/forum/go_quote.gif I've heard cell phone noises if I had it near my headphone cable.

Hmm, maybe it has even nothing to do with the DAC1 in this case but the noise is inducted directly into the cable.

Quote:

Originally Posted by riverlethe /img/forum/go_quote.gif There was even a study recently saying that sleeping too close to your cell phone can disrupt your sleep cycle...

I've heard that, too. However depending on the network's "Periodical Location Update (PLU)", I wouldn't give too much about this. In the case of the German provider T-Mobile for instance, the mobile will send an update every 6 hours while just listening the other period. Hence the exposure should be almost zero when in standby.

 

[Terje]

A DAC1 computer audio tweak
Odyssey Audio HK Forum - eeepc + Benchmark DAC1 Pre = great sound!

 

[infinitesymphony]

Quote:

Originally Posted by Terje /img/forum/go_quote.gif A DAC1 computer audio tweak Odyssey Audio HK Forum - eeepc + Benchmark DAC1 Pre = great sound!

That looks more like an advertisement to me... The head administrator of Odyssey Audio posts in his own forum that his equipment magically makes the DAC1 sound better, without any kind of objective testing or results.

"We again proved that there are science and technique behind hifi instead of myth."

No, not really... No proof.

 

[furball]

Hi Elias,

I have 2 questions regarding the SPDIF/AES BNC input. The manual says that the DAC1 comes with a BNC-to-RCA adapter. It also says,

"TIP: Shielded 75-Ohm coaxial cable is highly recommended for stable performance. Do not use 50-Ohm cables."



My questions are,

1) do consumer grade coaxial cables have 75 ohm impedance of 50 ohm impedance?

2) With the supplied BNC-to-RCA adapter, does this mean that I can use a consumer grade coaxial cable to connect the coaxial out from my source to the coaxial in of the DAC1?

 

[little-endian]

Hi furball,

the following from my side in advance until Elias replies:

Quote:

Originally Posted by furball /img/forum/go_quote.gif 2) With the supplied BNC-to-RCA adapter, does this mean that I can use a consumer grade coaxial cable to connect the coaxial out from my source to the coaxial in of the DAC1?

Actually, it is a RCA-to-BNC converter since the input is the BNC-interface (at this point by the way, I really wonder why Benchmark decided to use RCA for the analog output instead of BNC as well).

You may use any coaxial consumer source to feed the DAC1. It won't matter if the consumer or the prosessional format is used, it recognizes both. At least I had no problem with my DVD-Player and a cheap cinch-cable to the DAC1, at all. However, I prefer the optical way.

 

[Covenant]

/pines away for his answer

I'm in the planning stages for my B22 amp at the moment, so i need to know about that DC offset issue to make sure the DAC1 is the amp i want to purchase

 

[furball]

Thanks for the answers!

I am going to use the coaxial connection because when I was placing my order with monoprice, I was too cheap to order that premium optical cable, I ordered a coaxial cable instead.

Quote:

Originally Posted by little-endian /img/forum/go_quote.gif Hi furball, the following from my side in advance until Elias replies: Actually, it is a RCA-to-BNC converter since the input is the BNC-interface (at this point by the way, I really wonder why Benchmark decided to use RCA for the analog output instead of BNC as well). You may use any coaxial consumer source to feed the DAC1. It won't matter if the consumer or the prosessional format is used, it recognizes both. At least I had no problem with my DVD-Player and a cheap cinch-cable to the DAC1, at all. However, I prefer the optical way.

 

[Wavelength]

Quote:

Originally Posted by furball /img/forum/go_quote.gif Hi Elias, I have 2 questions regarding the SPDIF/AES BNC input. The manual says that the DAC1 comes with a BNC-to-RCA adapter. It also says, "TIP: Shielded 75-Ohm coaxial cable is highly recommended for stable performance. Do not use 50-Ohm cables." My questions are, 1) do consumer grade coaxial cables have 75 ohm impedance of 50 ohm impedance? 2) With the supplied BNC-to-RCA adapter, does this mean that I can use a consumer grade coaxial cable to connect the coaxial out from my source to the coaxial in of the DAC1?

Furball,

SPDIF is always better when used with BNC 75 ohm cables. There really is no way to make an RCA cable 75 ohm's though many claim to have done this the problem is the connector is the termination and impedance is mostly declared by what is called diameter over diameter. This is the ratio between the outside ground connector and the inside signal connector. You can see on a BNC that the center conductor is very small. Someone ounce said that for an RCA connector with it's fat center to be 75 ohms the outside ground connection needed to be something like 5" in diameter.

Radio Shack does have a real nice RCA->BNC gold connector if your souce does not have the BNC. But it is best to use a BNC cable if you can find a good one.

My fav and one that has been tested by a number of magazines is the Nirvana Audio T2 cable. I did tests using this and a number of other cables and the results were pretty staggering.

~~~~~~~~

LE--- RCA's are great for the audio connection mainly because they have existing cables that work well with them. Using 75 ohm BNC's would not make any sense for audio use.

Thanks
Gordon

 

[Crowbar]

Faux-75 ohm RCA:
Canare Corp. - Quality Cables and Connectors: RCA Crimp Plugs

 

[furball]

Thank you Wavelength and Crowbar!

 

[Scrith]

Quote:

Originally Posted by Wavelength /img/forum/go_quote.gif My fav and one that has been tested by a number of magazines is the Nirvana Audio T2 cable. I did tests using this and a number of other cables and the results were pretty staggering.

Hmm, I did a Google search to find out more about these cables and the only thing I found was that Wavelength and Nirvana Audio shared booths at a couple of CES shows (what a strange coincidence!).

What exactly are these tests you performed, and what was so staggering about the results?

 

[Wavelength]

Quote:

Originally Posted by Scrith /img/forum/go_quote.gif Hmm, I did a Google search to find out more about these cables and the only thing I found was that Wavelength and Nirvana Audio shared booths at a couple of CES shows (what a strange coincidence!). What exactly are these tests you performed, and what was so staggering about the results?

Scrith,

You can go here to see more info on Steve's cables:

Nirvana Audio - Products

The basic test I do on any SPDIF cable is three fold. I measure it's ability to deliver the Master Clock output into a known dac. I then determine it's ability to recover data checking for errors and finnally the amount of jitter attenuation it has.

I have the Prism dScope III Audio Test set it allows me to measure percisely all parameters of SPDIF cables, dacs, usb/firewire/ethernet dacs.

The FFT analyer on this puppy is good to better than -175dB and the only analyzer available that can test natively for computer audio.

The Nirvana T2 uses a patent that assures the 75 ohms impedance into the RF range and also down into the audio range.

This was one of the reason's why we shared suites at CES. I found Steve's cables to be worthy of the price. Which is not something I can say for most of the cable makers out there.

Why in the world should speaker cables be $18K for a pair in copper. Common....

Thanks
Gordon