Review : AUDINST HUD-MX1 DAC/amp - a promising newcomer (compared to Audio-gd FUN, AMB Gamma2)
Oct 27, 2011 at 12:15 PM Post #332 of 418
 
Quote:
Can it output optical sound and audio to my headphones at the same time?
 
Yes, you can. No problems here.
 
 
I had never used Wasapi actually, but from my experience, Foobar2000 can works with a single output device. You'll have to chose it that device manually. But you can always use Winamp (+ wasapi plugin ) and set it play your music from different output device simultaneous with Foobar2000. 
 
Dec 6, 2011 at 12:18 AM Post #334 of 418
Do you guys think that the Audinst HUD-MX1 would pair nicely with the Sennheiser HD 598. I'm kind of looking for a DAC/Amp solution under $200. I was also looking into the E9 + E10 combo, again, under $200.
 
Dec 6, 2011 at 10:51 AM Post #335 of 418


Quote:
Do you guys think that the Audinst HUD-MX1 would pair nicely with the Sennheiser HD 598. I'm kind of looking for a DAC/Amp solution under $200. I was also looking into the E9 + E10 combo, again, under $200.



yes it would power the HD598 very nicely. I use mine sometimes to power my HD600, and it works great. If you ever want to upgrade,
you can still use the MX1 as a stand alone DAC (which is how I use it most of the time).
 
 
 
Dec 6, 2011 at 1:36 PM Post #336 of 418
Saturn , Audinst Hud-MX1 is gonna give you higher SQ then E9 + E10 combo in most case, especially for low-impedance headphone like HD598.
Why ? Because DAC section of Audinst is much, much better then E10 DAC, so, you wouldn't benefit much from that extra power E9 give...  
 
Dec 6, 2011 at 4:02 PM Post #337 of 418
Thanks, for your inputs. Just purchased the Audinst! Will report back with my impressions! 
 
Quick question (& please excuse my noobness), but how do I go about replacing the op amps in the unit?
 
 
In this picture, I see 3 opamps. I plan on buying either LT1028ACN8 or the AD797BRZ opamp. Does that mean I have to purchase 3 of the same op amp and replace them with the current ones?
 
Dec 6, 2011 at 11:11 PM Post #338 of 418
no. you just need to buy one or two depending on the opamp. some opamps like the opa627 will need some kind of adapter like a browndog adapter.
 
Jan 25, 2012 at 5:06 AM Post #339 of 418
 
Could anyone possibly recommend me a good linear regulated power supply (kit or full product) for this amp?  I need a good 15V power supply for my Audinst HUD-MX1.
 
I'm looking at something like this right now:
http://www.analogmetric.com/goods.php?id=2211
It looks fairly high quality but remains economical.
 
Another question:  How much current does the Audinst need feeding it from the power supply when it is driving a set of 600Ohm headphones?  I need to choose an appripriate transformer, as I want it to be as compact as possible while providing enough power to run the thing.
 
EDIT:  Screw it I'm taking the DIY route and making a 1A linear regulated power supply of my own.  You can check out my schematics and stuff here.
 
Feb 9, 2012 at 11:25 PM Post #340 of 418


Quote:
 
Could anyone possibly recommend me a good linear regulated power supply (kit or full product) for this amp?  I need a good 15V power supply for my Audinst HUD-MX1.
 
I'm looking at something like this right now:
http://www.analogmetric.com/goods.php?id=2211
It looks fairly high quality but remains economical.
 
 
Another question:  How much current does the Audinst need feeding it from the power supply when it is driving a set of 600Ohm headphones?  I need to choose an appripriate transformer, as I want it to be as compact as possible while providing enough power to run the thing.
 
EDIT:  Screw it I'm taking the DIY route and making a 1A linear regulated power supply of my own.  You can check out my schematics and stuff here:  http://wp.me/s1OOFO-yzlrps


If you feel motivated, you can always build a σ11 http://www.amb.org/audio/sigma11/
 
If I end up buying the Audinst, I'll build a sigma 11... if not just for the fun of it 
biggrin.gif

 
 
Feb 12, 2012 at 2:04 AM Post #341 of 418
I wanted to measure the current to see if a 1 amp supply has enough headroom, since it might become unstable when pushed close to the max.  Since I needed to cut the wires to attach my DMM, I sacrificed a Linksys router 12V, 1.5A supply. The HUD-MX1 is labeled 12V-15V, and this question is from the Audinst forums:
 
Yangorang
#4 Wed Jan 25, 2012 9:32 pm
Member Registered: Jan 2012
Posts: 3
Does it make much of a difference whether we use a 12V or 15V power supply?
audinst
#5 Thu Jan 26, 2012 4:27 am
Administrator Registered: Jan 2010
Posts: 42
There's no difference between 12v and 15v power supply, but we recommend using 15v because it makes the power supply more stable from inside the circuit.
 
The test setup was AC outlet------PSU wart------DMM------HUD-MX1
My DMM does not have a peak hold feature, and when playing music, the display changes to fast to get a precise reading.  On the milliamp scale, it goes something like this:
Hundreds: stable
Tens: Changes in a blink of the eye
Ones: Just a blur
 
First I measured in low gain with Fostex T40RP. I set the headphones on the table, so I could crank the volume far beyond sane listening levels.  At max volume the peaks were about 220 milliamps.  Then I switched to high gain, and to really stretch the amp, I put the T50RP in the 1/4 jack and my Denon d2000 in the 1/8 jack at the same time.  It peaked about 430 miliamps. 
 
I will stick with the stock adapter until I see more evidence regarding the benefit of an upgrade.
 
Feb 12, 2012 at 2:33 AM Post #342 of 418
Thanks for the details, Sardonyx =)
 
The thing that bugs me is that the stock wall wart seems to be a switching power supply. I am curious as to how quiet the DC it outputs really is. Though I am aware that the HUD MX1 has a complex set of on-board power rails with dedicated regulators, if less noise gets inside the unit, then less noise should get out of it, no?
 
Another point to address is power reserve. The HUD MX1 has a crying lack of capacitors, I feel like it would be happy with more.
 
see http://www.head-fi.org/t/484163/review-audinst-hud-mx1-dac-amp-a-promising-newcomer-compared-to-audio-gd-fun-amb-gamma2/225#post_7198272
 
Building a high quality external PSU with a fair amount of power reserve (capacitors) sounds like a good idea to me.
 
Feb 12, 2012 at 5:48 PM Post #343 of 418
Thanks Sardonyx for taking the time to take those measurements; it is interesting to see that the Audinst uses less than 500mA even while driving two headphones at max volume.  This shows that a 1A 15V power supply for the Audinst is definitely more than enough.
The issue with the stock power supply is not really the max output current though, it’s that it is a fairly low quality switching power supply.  A good DIY linear regulated power supply should have much lower output ripple and better transient response as well.
 
audiofil reports that his TREAD does a pretty good job: [1] [2] [3]
 
Mike from Headphonia also tells me that battery power provides some improvement as well and also mentions that the internal regulation of the Audinst is rather lacking.  Indeed I didn't see anything too impressive in the power department when looking around inside the Audinst, but I am somewhat hesitant to start desoldering stuff on the inside without being 100% sure of the layout.
 
For me I think I'm going to stick with DIYing my own LM340 based LRPS and perhaps look into making a USB isolator as well later on since according to chrisc0 the Wolfson DAC is still powered by the 5V through USB even when using an external PS. 
I am somewhat curious about changing out the LME49860 as well since it's already a very high end part to begin with - I'm looking at perhaps getting some LME49990 or LME49722 samples as these things look fairly well on par with the AD797BRZ.
 
EDIT:
Here's actually the datasheet for the stock Audinst power supply:  link
It specifies 150mVpp max ripple; not a particularly high performance unit - I think you get something like 1/1000th of that with a high quality LRPS.
 
Feb 12, 2012 at 7:06 PM Post #344 of 418

 
Quote:
The issue with the stock power supply is not really the output current though, it’s that it is a fairly low quality switching power supply.  A good DIY linear regulated power supply should have much lower output ripple and better transient response as well.

 
This is exactly what I was thinking. Good to know someone else shares this point.
 
 
Quote:
Mike from Headphonia also tells me that battery power is an improvement as well and also mentions that the internal regulation of the Audinst is rather lacking.  Indeed I didn't see anything too impressive when looking around inside the Audinst, [http://i429.photobucket.com/albums/qq20/Yangorang/Audinst%20HUD-MX1/CIMG0568.jpg] but I am somewhat hesitant to start desoldering stuff on the inside without really knowing the topology.  


 

I thought about that too. Given how the input voltage needed is between 12 and 15v, I would try to power it from a 12v lead-acid battery. Though I would make sure the battery is not charged over 15v before connecting it to the Audinst. A battery has a virtually perfect DC current and a large enough one would have plenty of power reserve. I would definitively try it out if I had the Audinst. 
 
I'm surprised about his comment on the audinst lacking regulation... the product page makes it look like it has a solid set of regulators. I suppose a reviewer is more reliable than the commercial page though. If this is really the case, then it would make even more sense to get a linear regulator for the Audinst.
 
Feb 12, 2012 at 8:10 PM Post #345 of 418

Quote:
 
I'm surprised about his comment on the audinst lacking regulation... the product page makes it look like it has a solid set of regulators. I suppose a reviewer is more reliable than the commercial page though. If this is really the case, then it would make even more sense to get a linear regulator for the Audinst.


It's not that it lacks regulation he just said:  "A friend of mine tried to power the Audinst with an SLA battery once. I think he reported an improvement (after all it's clean battery power), though he also comments that the quality can be even better if not for the internal regulation."
 
I'd be curious to try the battery power out for myself but I don't think I'd want to deal with it for everyday use.
 
I was able to do a bit of testing on my DIY LRPS vs the stock Audinst one and here's what I found:
[size=small]I tested this power supply vs the stock Audinst HUD-MX1 power supply by loading them to 150mA of output current for about an hour and AC coupling the output to a 101gain op-amp in non-inverting configuration.  This way I could use the smallest range on my benchtop DMM to get an idea of the ripple voltages.[/size]  [size=small]The stock Audinst HUD-MX1 switching power supply measured 1.6mVrms ripple which is not bad at all for a switching unit.  My prototype LRPS measured 0.08mVrms which is expected for a linear regulated power supply.  The Audinst stock unit is actually not too bad as far as swtiching power supplies go, but for a bit of your time and money you can do quite a bit better and learn something in the process by building yourself a nice little LRPS.[/size]
 
[size=small]I'm sure that a similar improvement could be had from using some sort of [/size][size=small]USB Isolator[/size][size=small] since the USB power bus is probably even worse than a switching power supply.[/size]
 
 

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