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Benchmark DAC1 now available with USB - Page 59

post #871 of 3034
9/13/07 at 3:27pm
zkn,

The gain level of the headphone outputs were purposely designed to accommodate professional applications where analytical monitoring is extremely important.

The output attenuators do not affect the headphone outputs.

Which Genelec monitors are you using?

Thanks,
Elias
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post #872 of 3034
9/13/07 at 3:58pm
8030a+7050b

I'm forced to run the sub through speakers because of this. If run through the subwoofer first, its volume is fixed to the maximum and the gains on the speakers don't have affect it. It's no problem though but the headphone out volume pot issue is kind of a bummer.

Can anyone else confirm the position of the pot with stock HD650 unbalanced through headphone out?
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post #873 of 3034
9/13/07 at 4:57pm
quoted from Genelec 8030a manual:

Quote:
The input sensitivity of the loudspeakers can
be matched to the output of the mixing console
or other source by adjusting the volume
control on the front panel
The volume control (gain) of the 8030's should be turned all the way down to accommodate the maximum signal amplitude from the DAC1. It is highly recommended to configure in this manner because maintaining maximum signal amplitude from the DAC1 to the amplifier/speaker will maximize the signal-to-noise ratio and minimize distortion in the amp. This is true from any source to any load. This is standard practice in professional recording and broadcasting facilities for this reason.

Thanks,
Elias
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post #874 of 3034
9/13/07 at 5:14pm
The headphone output of the DAC1 is very strong. My DAC1 USB drives Shure E500s, and by the time I get to 9:00 on the volume pot my ears are being turned inside out. In the bedroom I have a standard DAC1 driving Sennheiser HD25s, and the same applies. Fortunately the pot is even better balanced than Elias has said, so it's not a big problem. The most frustrating aspect is that the steps in volume are large at that point, so finding the volume I want is a challenge. Sometimes I end up having the music louder than I'd really prefer.

I'd like to see the Benchmark folks look into this, and perhaps offer a front-panel output attenuator switch that could be set to -10dB, -20dB and -30dB. This would accommodate high-efficiency headphones.

Off-topic: a headphone board, and its spell-check program doesn't know Sennheiser?
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post #875 of 3034
9/13/07 at 5:42pm
Quote:
Originally Posted by EliasGwinn View Post
Its difficult to say whether the DAC1 USB's output drivers will affect the quality of sound, because it depends on the input capacitance of the GS-X, as well as the type and design of the input stage (i.e., discrete, transformer, etc). They don't offer any of this information on their website (actually, I couldn't find any information at all...only pictures...???).

the GS-X info is not posted on the Headamp website but it is a balanced version if the GS-1 which is the 50k OHM impedance spec i quoted.

http://www.headamp.com/home_amps/gs1/index.htm

i am going to contact Headamp to find out the exact specs on the GS-X and hopefully get that capacitance figure for you.

regarding the DAC1 headphone out, i am using my computer media software as Benchmark suggests, Winamp and Foobar set to 100% and 100% on Windows volume. whith this setting my 42ohm Audio Technica W5000 and AD2000 can get to about step 4 or 5 which is just past the point of the right channel kicking in after the initial pot imbalance, so i have virtually no volume control. the Senn HD650 which are 300 OHM will get to about 9:00 or step 10, i cant detect any imbalance at that setting but as pointed out the volume steps are fairly high.

i could always lower the volume in software but i dont want to introduce digital distortion as pointed out by Elias earlier.

how many additional volume steps can i expect from the 10db down setting on the DAC1 USB?
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post #876 of 3034
9/13/07 at 6:32pm
Quote:
Originally Posted by EliasGwinn View Post
quoted from Genelec 8030a manual:

The volume control (gain) of the 8030's should be turned all the way down to accommodate the maximum signal amplitude from the DAC1. It is highly recommended to configure in this manner because maintaining maximum signal amplitude from the DAC1 to the amplifier/speaker will maximize the signal-to-noise ratio and minimize distortion in the amp. This is true from any source to any load. This is standard practice in professional recording and broadcasting facilities for this reason.
Interesting. At work I have Genelec 8020As driven by a USB DAC1, and I dropped the internal XLR jumpers way down so I could keep the volume on the 8020As at the max level. The reason I did this is that the volume pots on the speakers are not stepped, so it's a hassle to balance them each time I power on the Genelecs. Is it a mistake to drive them with their volume at max?

I also use my USB DAC1 with e500s, and like others can't get past 9:00... But I've not noticed any sort of channel imbalance. It would be nice to have more usable range, however.

Finally, when outputting from the USB DAC1's RCAs to my headphone amp (Triad Audio Lisa III XP), I can't get the volume control past 9:00 when driving my Senn HD650s. My e500s don't even stand a chance. There is no way to attenuate the RCA output, correct? I suppose I could have the gain on the head amp dropped down.
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post #877 of 3034
9/13/07 at 7:43pm

Need help!

So the the Output Level switch on the rear has three positions; down is variable, up is calibrated and middle is ???

What should this be switched to when:

1. Using the headphone out of the DAC1?

2. Using the RCA outs to a dedicated headphone amp or receiver (so as to bypass the volume control on the DAC1)?
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post #878 of 3034
9/14/07 at 1:33am
Quote:
Originally Posted by EliasGwinn View Post
The volume control (gain) of the 8030's should be turned all the way down to accommodate the maximum signal amplitude from the DAC1.
turned all the way down? there would be no sound then

do you mean maxed out?
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post #879 of 3034
9/14/07 at 10:14am
Quote:
Originally Posted by Lord Chaos View Post
I'd like to see the Benchmark folks look into this, and perhaps offer a front-panel output attenuator switch that could be set to -10dB, -20dB and -30dB. This would accommodate high-efficiency headphones.
Thanks for the feedback...it is extremely valuable to us. We have discussed this and will definitely take it into consideration when planning future products and services.

And, please don't think that I'm just saying some generic PR b.s. I'm very serious when I say this because you all (head-fi community) have contributed so much to our understanding of what the user wants and needs. For example, we put the 10 dB gain reduction in the headphone amp of the DAC1 because of user feedback.

And now we are finding out that the gain needs to be reduced even further. I'm not sure when we can provide a product or service to remedy this situation, but we will look into it with complete earnestness.

Thanks,
Elias
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post #880 of 3034
9/14/07 at 10:59am
Quote:
Originally Posted by euclid View Post
i could always lower the volume in software but i dont want to introduce digital distortion as pointed out by Elias earlier.
With Windows, you can use the system volume control mixer (the gray mixer with the faders). It causes very little (almost no) distortion. However, as with any digital volume control, you will lose word-length as you decrease the volume. That is, every 6 dB of digital attenuation results in 1-bit decrease. This is why we see our analog volume control as a big advantage over D/A's with digital volume control.

Quote:
Originally Posted by euclid View Post
how many additional volume steps can i expect from the 10db down setting on the DAC1 USB?
The HPA2 (headphone amp) volume of the DAC1 USB w/ 10 db gain reduction is approximately 8 steps below that of the DAC1 HPA2 w/ no gain reduction. In other words, with the 10 dB HPA2 gain reduction, you can turn up the volume knob +/- 8 more steps before you reach the same volume as with no gain reduction.

Thanks,
Elias
Reply
post #881 of 3034
9/14/07 at 11:07am
Quote:
Originally Posted by gregeas View Post
Interesting. At work I have Genelec 8020As driven by a USB DAC1, and I dropped the internal XLR jumpers way down so I could keep the volume on the 8020As at the max level. The reason I did this is that the volume pots on the speakers are not stepped, so it's a hassle to balance them each time I power on the Genelecs. Is it a mistake to drive them with their volume at max?
Well, good question... This, along with this point made by zkn:

Quote:
Originally Posted by zkn View Post
turned all the way down? there would be no sound then

do you mean maxed out?
Let me ask you both... Do these Genelec's go to 'full-off' when you turn the volume all the way down?

The reason I ask: if they go all the way to 'full-off', chances are that they are attenuator controls, not gain controls. In other words, the gain may be fixed, and the front panel knobs may only attenuate the incoming signals.

I'm curious to find out...

Thanks,
Elias
Reply
post #882 of 3034
9/14/07 at 11:17am
Quote:
Originally Posted by gregeas View Post
...when outputting from the USB DAC1's RCAs to my headphone amp (Triad Audio Lisa III XP), I can't get the volume control past 9:00 when driving my Senn HD650s. My e500s don't even stand a chance. There is no way to attenuate the RCA output, correct? I suppose I could have the gain on the head amp dropped down.
The RCA outputs of the DAC1 (USB) are configured to match that of most common consumer audio devices, such as CD players, etc. The best thing to do, in your case and in general, is to minimize the gain on the downstream device to allow maximum signal amplitude from the source.

Another thing you can do, if you want, is run the DAC1 in calibrated mode and adjust the calibration potentiometers in the back of the DAC1 to suit your headphone amp. To do this, you will want to use a digital test tone (I can post one to use via the computer, or you can buy a test CD) and a multimeter to make sure the balance between channels is accurate.

Thanks,
Elias
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post #883 of 3034
9/14/07 at 11:23am
Quote:
Originally Posted by wakeride74 View Post
So the the Output Level switch on the rear has three positions; down is variable, up is calibrated and middle is ???
The middle position will mute all analog outputs except the HPA2 (headphone) outputs. This is to allow you to mute your speaker system when you want to listen solely via headphones. The DAC1 USB will allow you to do that simply by plugging the headphones in the left output of the HPA2 - the other analog outputs will mute automatically.

Quote:
Originally Posted by wakeride74 View Post
What should this be switched to when:

1. Using the headphone out of the DAC1?
See above.

Quote:
Originally Posted by wakeride74 View Post
2. Using the RCA outs to a dedicated headphone amp or receiver (so as to bypass the volume control on the DAC1)?
The 'Calibrated' position of the switch will bypass the volume control of the DAC1.

Thanks,
Elias
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post #884 of 3034
9/14/07 at 11:46am
Quote:
Originally Posted by EliasGwinn View Post
Well, good question... This, along with this point made by zkn:

Let me ask you both... Do these Genelec's go to 'full-off' when you turn the volume all the way down?
Yes, I just tested my Genelecs. With their volume set at 0, at the DAC1 maxed, I hear nothing out of the speakers.
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post #885 of 3034
9/14/07 at 12:43pm
I believe the 8020 have the on/off integrated on the gain control pot and my 8030 have on/off switch separated.

Either way, there's absolutely no sound with 8030 either when power on but gain at zero.
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