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Benchmark DAC1 now available with USB
Nov 8, 2009 at 6:16 PM Post #2,779 of 3,058
I know this forum covers mostly head-fi gear but i also connectan active speakers to my DAC1 Pre.

i'm on the verg to upgrade my interconnects to my Dynaudio BM6A MKII and is choosing between a Nordost Baldur and the Furutech Evolution.

Elias, do you have any expert opinion on these cables?

Thanks in advance!
 
Nov 9, 2009 at 4:14 PM Post #2,780 of 3,058
Quote:

Originally Posted by john11f /img/forum/go_quote.gif
I know this forum covers mostly head-fi gear but i also connectan active speakers to my DAC1 Pre.

i'm on the verg to upgrade my interconnects to my Dynaudio BM6A MKII and is choosing between a Nordost Baldur and the Furutech Evolution.

Elias, do you have any expert opinion on these cables?

Thanks in advance!


I'm sorry, but I don't know enough about those models of cables to advise you.

All the best,
Elias
 
Nov 9, 2009 at 4:18 PM Post #2,781 of 3,058
Quote:

Originally Posted by Shadorne /img/forum/go_quote.gif
In theory yes (isolated on a lab bench), however, the noise floor also depends as much on the gain (or input sensitivity as anything else). A more powerful amplifier operating with low input sensitivity (needs a high signal to drive it) may be quieter than a less powerful amplifier operating with high input sensitivity. This is because the high input sensitivity can compromise the S/N or dynamic range from the pre-amp and you end up amplifying the inherent noise floor of the output of the preamp.

My point is that only 10 db separate normal amplifiers from powerful ones. One cannot assume that absolute maximum "power output rating" will necessarily determine the noise floor. For instance, the design of the input stage (balanced versus RCA) may play a bigger role in the "real world" than whether the amp maximum power is rated 100 watts or 200 watts in to an 8 ohm load. (Ground loops being a significant source of hum or noise floor in the real world)
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I agree 100%.

Best,
Elias
 
Nov 13, 2009 at 4:24 AM Post #2,782 of 3,058
Quote:

Originally Posted by EliasGwinn
... the ideal amp will drive YOUR speakers to YOUR comfortable listening level when the DAC1's volume control is between 11 o'clock and 3 o'clock...



Sorry to not check-in for a while - over here we've been enjoying the music!
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Elias just for the record, I understood what you were saying - for example, I took the above comment of yours to be very clear indeed.

Elias, your excellent advice has audibly paid off in spades for us - thanks again for explaining how/why finding an amplifier that ideally meets your above-quoted description (which was not easy by the way), is much desireable. Our previous nice amp was very powerful but way too loud for us at the DAC1's optimal volume control positions, e.g. most especially when approaching 3 o'clock on the DAC1 volume dial. I'm absolutely certain that some others in similar positions could also benefit from your advice here, about getting the right-performing amp as you've described, if they get a chance to try it. Either way, for my family, your advice (as always) has really helped - and we keep enjoying it each day. You're the best!
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Nov 23, 2009 at 2:32 PM Post #2,784 of 3,058
Hi Elias,

I just received my DAC1 HDR and will be trying out some K702s in a week. What are the best jumper settings for the headphone amp gain for the K702/K701? I know you said you've used the K701, which is the same headphone. Should I go ahead and set it to A or B or OFF (i.e -10, -20, or 0)?
 
Nov 23, 2009 at 4:36 PM Post #2,785 of 3,058
Quote:

Originally Posted by urbo73 /img/forum/go_quote.gif
Hi Elias,

I just received my DAC1 HDR and will be trying out some K702s in a week. What are the best jumper settings for the headphone amp gain for the K702/K701? I know you said you've used the K701, which is the same headphone. Should I go ahead and set it to A or B or OFF (i.e -10, -20, or 0)?


It depends on the type of music you will be playing and your preferred listening levels. The best jumper settings will allow you to achieve a mild-yet-adaquate listening level at 11 o'clock on the volume knob while playing your loudest music. If it is too loud at that position, move from 'A' to 'B'. If you can't get your 'quiet' music loud enough, move from 'A' to 'OFF'.

If you have additional questions, please feel free to ask!

All the best,
Elias
 
Nov 24, 2009 at 4:04 AM Post #2,786 of 3,058
Thanks Elias. I will see, though I thought it was not source dependant, but more how much mW it would output and what's the correct power for each headphone.

BTW, I have the DAC1 HDR sitting on a shelf (i.e. not in a rack with open air underneath) and it's very warm even when off! Is that normal?? Why is that? Also when on, how does it ventilate and cool? Weird..
 
Nov 24, 2009 at 4:10 AM Post #2,787 of 3,058
Hi Elias,

I have an old Benchmark DAC1 Rev H. I'm using it to drive a Bryston 4B-SST power amp, and recently I discovered that the XLR connection sounds different from the RCA connection to the power amp (after volume matching). The XLR output sounds distinctly higher, as if passed through a high-pass filter, and to me the RCA output sounds more correct. I don't think it's a cable issue because I've tried different cables of both types. I'm not sure if it's DAC1 or the amp, but I don't have another amp with balanced inputs to test.

Again, I'm not sure if the issue is with the DAC1, but do you have any intuition as to why there may be a difference?

Thanks.
 
Nov 24, 2009 at 2:26 PM Post #2,789 of 3,058
Quote:

Originally Posted by urbo73 /img/forum/go_quote.gif
Thanks Elias. I will see, though I thought it was not source dependant, but more how much mW it would output and what's the correct power for each headphone.


It does that to a certain extent, but there is a lot of overlap between the three selections. Its really meant to be a 'volume' adjustment - something that allows each user to set the overall output-level range to optimize the volume potentiometer performance.

Quote:

Originally Posted by urbo73 /img/forum/go_quote.gif
BTW, I have the DAC1 HDR sitting on a shelf (i.e. not in a rack with open air underneath) and it's very warm even when off! Is that normal?? Why is that? Also when on, how does it ventilate and cool? Weird..


It is normal...the voltage regulators are strapped to the chassis, so the entire chassis acts as a heat sink. That is why it feels warm.

It should feel like a mug of coffee...that is normal. This is true when it is 'On' or in 'Standby'. The internal electronics are never shut-down unless the power to the unit is disconnected.

All the best,
Elias
 
Nov 24, 2009 at 2:50 PM Post #2,790 of 3,058
Quote:

Originally Posted by JMS /img/forum/go_quote.gif
Hi Elias,

I have an old Benchmark DAC1 Rev H. I'm using it to drive a Bryston 4B-SST power amp, and recently I discovered that the XLR connection sounds different from the RCA connection to the power amp (after volume matching). The XLR output sounds distinctly higher, as if passed through a high-pass filter, and to me the RCA output sounds more correct. I don't think it's a cable issue because I've tried different cables of both types. I'm not sure if it's DAC1 or the amp, but I don't have another amp with balanced inputs to test.

Again, I'm not sure if the issue is with the DAC1, but do you have any intuition as to why there may be a difference?

Thanks.


I can only guess, as I've never heard of this before. My guess is that it has something to do with the differences between the designs of the RCA and XLR input stages in the amplifier. Possibly the DC coupling or input transformer of the XLR stage is causing significant low-frequency attenuation.

The XLR and RCA outputs on the DAC1 use the exact same signal source and components.

All the best,
Elias
 
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