Geek Pulse: Geek desktop DAC/AMP by Light Harmonics

[wingsounds13]

What gain level do you have the headphone amp set to? It seems like you could make good use of the low gain setting. Some experimentation is still in order, as I have found. My ZMF Master model V1 headphones are 50 ohms and medium/low sensitivity. From the balanced output, I can get plenty loud on low gain with most source material. Most listening is about -10dB. However... With my setup, I find that I get better sound on high gain and -24dB. Your results may be different.

The Pulse DAC headphone amp unbalanced output is 7V RMS and 3W into a 16 ohm load. This is sufficient power to drive almost any headphones to a potentially dangerous level. The HD-800 is a high impedance headphone and is fairly sensitive, so it does not need much power, but does need an amp with a reasonably high voltage output.

J.P.

 

[wingsounds13]

As for sample rate, the Pulse is supposed to be capable of 32/384 PCM, DXD and eventually DSD 256, although the current drivers and firmware are limited to DSD 128 as DoP.

J.P.

 

[mscott58]

As for sample rate, the Pulse is supposed to be capable of 32/384 PCM, DXD and eventually DSD 256, although the current drivers and firmware are limited to DSD 128 as DoP.

J.P.

There's also a working Beta for the 256 driver, so that should hopefully be out for public use pretty soon. Cheers

 

[adrian0115]

  I did. XFi was pretty much ignored, I guess. They say they still didn't have the boards in for them, but according to their estimated response by customer service, they should've gotten them in almost a month ago. If you check their estimations and charts and timelines, none mention XFi. Infinity, X, and standard are all that is listed anywhere

Jeez, this problem with PCB's have been there since the beginning and still haven't been solved.  I would've thought it would be in both parties best interest to figure it out since scrapping populated/unpopulated PCB's would get pretty costly...sigh.
 
More surprisingly is the Xfi should outnumber the Infinities so it's interesting how the Infinity went from not being for retail to replacing the Xfi for retail.  
 
Regardless, it looks like Xfi/Infinity all stopped now since there's impedance problems with the PCB's.  
 
I wonder who is making the Vi PCB's and why not use them to run the Xfi/Infinity as well. 

 

[pedalhead]

Incredible that original Xfi backers are still waiting.  Wow.
 
On the topic of neutrality of sound with the Pulse....personally I've found my Infinity to have a bit of a boost around 8-10khz, which gives some additional air to snare drums etc but may perhaps contribute to a perceived corresponding dip in bass response.

 

[NigelJ]

Just curious what headphones were these (Geek Pulse) designed to power? My friend sent me the pulse to try with my HD800. I have the amp set to -13.5 dB and the volume on my computer at 20% and its perfectly loud. The one time I set the amp to 0 it killed my ears from over-amping. 

Also is 32/192 the max obtainable sample rate using usb? Its overkill to begin with but curious how one would get above this using usb. 

Are you sure that the computer is is only outputting at 20%? As far as I have read, still waiting for my Infinity so can't confirm, the volume is controlled by either the computer or the Pulse volume knob, not by both. If you actually are using a 20% volume on the computer you are limiting the maximum quality as you are resampling the signal in the computer and then again in the Pulse; if you need to use a lower setting on the computer set a reduction that is exactly a factor of 2, ie 50% or 25% as this only requires a bit-shift not resampling.

(A similar situation applies to using the Pulse with an external amplifier - use a reduction that is a multiple of -3 dB, ie -3 dB, -6 dB, -9 dB, -12 dB, etc. This was discussed by Larry in one of the LH Labs HPA videos: https://m.youtube.com/watch?v=7gkHwQE8uYk&t=8m59s&feature=youtu.be.)

 

[mark5hs]

You might want to contact lh labs asap.. Good luck! (standard pulse, ordered Dec 2014... Received September 2015)

Yeah, just opened another ticket. I first opened a ticket in early November when an email proudly stated, "standard Pulse DACs have been shipped!", and was told that there were a few left to be shipped in the second half of November. Now, it's just about January and I'm still waiting... 

 

[MrMan]

Are you sure that the computer is is only outputting at 20%? As far as I have read, still waiting for my Infinity so can't confirm, the volume is controlled by either the computer or the Pulse volume knob, not by both. If you actually are using a 20% volume on the computer you are limiting the maximum quality as you are resampling the signal in the computer and then again in the Pulse; if you need to use a lower setting on the computer set a reduction that is exactly a factor of 2, ie 50% or 25% as this only requires a bit-shift not resampling.

(A similar situation applies to using the Pulse with an external amplifier - use a reduction that is a multiple of -3 dB, ie -3 dB, -6 dB, -9 dB, -12 dB, etc. This was discussed by Larry in one of the LH Labs HPA videos: https://m.youtube.com/watch?v=7gkHwQE8uYk&t=8m59s&feature=youtu.be.)

 
The pulse I don't think has a volume knob. It appears just to adjust the amount of amping.  
 
I had both working and now neither the pulse nor my computer will adjust the volume. I can still adjust the amp amount with the knob but not the volume. 
 
Now I have to listen to it @ 0dB volume to hear the music @ a decent level. 
 
The difference between adjusting volume vs amping is volume doesn't affect pressure on the ear. 
 

 
Adjusting this does nothing to the sound

 
 
What version I own

 

[miceblue]

The volume knob, or your computer, adjusts the Pulse's volume in the digital domain through the ESS DAC's multi-bit Delta-Sigma stage...

Only the gain (low, medium, high) adjusts things in the analogue domain.

No matter which option you choose, you're adjusting the perceived volume level.


Try cycling the Pulse off/on to see if that does anything. The Pulse seems to have issues connecting to USB interfaces for some reason. It happens to me and another fellow Infinity owner, as well as another Xfi owner.

 

[greenkiwi]

What gain level do you have the headphone amp set to? It seems like you could make good use of the low gain setting. Some experimentation is still in order, as I have found. My ZMF Master model V1 headphones are 50 ohms and medium/low sensitivity. From the balanced output, I can get plenty loud on low gain with most source material. Most listening is about -10dB. However... With my setup, I find that I get better sound on high gain and -24dB. Your results may be different.

The Pulse DAC headphone amp unbalanced output is 7V RMS and 3W into a 16 ohm load. This is sufficient power to drive almost any headphones to a potentially dangerous level. The HD-800 is a high impedance headphone and is fairly sensitive, so it does not need much power, but does need an amp with a reasonably high voltage output.

J.P.

I'm trying this with my LCD-XCs, my comfortably loud level is:
Low ==> -21dB  (24-27 is more of a long term listening level)
 
I'm going to try it on High Gain to see if I can hear a difference.  (with an accordingly lower volume setting)

 

[MrMan]

The volume knob, or your computer, adjusts the Pulse's volume in the digital domain through the ESS DAC's multi-bit Delta-Sigma stage...

Only the gain (low, medium, high) adjusts things in the analogue domain.

No matter which option you choose, you're adjusting the perceived volume level.


Try cycling the Pulse off/on to see if that does anything. The Pulse seems to have issues connecting to USB interfaces for some reason. It happens to me and another fellow Infinity owner, as well as another Xfi owner.

 
I tried turning pulse on/off. I tried removing usb cable and trying it in other usb slots. I tried uninstalling the drivers, restarting computer and then reinstalling the drivers. None of these work. When I go to window's playback devices and then look at the LH audio icon the bars next too it show no audio movement despite audio coming out of the headphones. To make sure windows was displaying audio properly I tried this with my xda2 and sennheiser sound card and both show audio perfectly.

 

[Audio Addict]

It may be a function of your software. With Roon, I have it set for a fixed output so the volume is controlled by the Pulse Infinity. Using JRivers is not so clean. JRivers controls the volume as well as the Pulse. If I switch to using the Geek Out V2+, I have to pull up the LHLABS driver and control the volume through it.

 

[miceblue]

I tried turning pulse on/off. I tried removing usb cable and trying it in other usb slots. I tried uninstalling the drivers, restarting computer and then reinstalling the drivers. None of these work. When I go to window's playback devices and then look at the LH audio icon the bars next too it show no audio movement despite audio coming out of the headphones. To make sure windows was displaying audio properly I tried this with my xda2 and sennheiser sound card and both show audio perfectly.

Then I'm not too sure what's going on. Audio plays through the headphones, but Windows doesn't recognise it. Strange.

 

[mscott58]

Then I'm not too sure what's going on. Audio plays through the headphones, but Windows doesn't recognise it. Strange.

Guess that's better than the other way around!

 

[miceblue]

Speaking of connection problems with the Pulse, my Infinity keeps losing its connection every few hours of use...it usually happens when I'm watching YouTube videos. I just wanna watch Star Wars: The Clone Wars!

Cycling the power off/on fixes the issue but that's supposedly bad for the femto clocks according to Larry.