anon65535
New Head-Fier
- Joined
- Oct 5, 2014
- Posts
- 11
- Likes
- 10
Howdy all -
I just received my new AK120 and putting through some complex testing in the lab with scopes, impulse, jitter, etc. runs to see how well it performs against some of my meridian explorer, ifi idsd, e17, x5, e12diy and other portable hifi stuff.
So far I'm finding some VERY interesting results around what ProEQ and Line Out actually does, and how the internal circuitry handles conversion when it comes to their SW filters internally with the dual WM8740s.
In the meantime in my past 24h with the stock ak120, all I can say is that I'm very impressed thus far! Been using SE535 reds, SE846s and beyer t51p's. The AK is beyond expectations with SE535s even compared to the SE846 (yes, I know about the impedance issue
and even the T51s.
What got me started, was a simple Q: What does the ProEQ really do? and is Line Out a SW switched Line Out?
Take a look at responses below with a dummy 32ohm load with ProEQ On vs. ProEQ Off. I've never seen such a thing before. I heard rumor that ProEQ is not truly an EQ, but rather a custom way that the AK handles the impedance changes with measured headphone frequency response. An EQ shouldn't be able to expand the frequency response all the way up into the ultrasonic range, but ProEQ seems to be doing that AND more.
Testing run dozens of times (ProEQ ON vs. ProEQ OFF):
Notice that at 20k there's nearly a 3.5db gain @ 20k ...then look into 20k+ ...I was stunned and can't replicate this on any of my other equipment.
Thinking I was crazy (which some call me) I put the DAC in the AK through 1000s of passes on by bench.
What you'll see below is a 24/192 impulse response (ProEQ OFF) showing the DAC processing normally a slow roll-off digital filter...and a great implementation at that! Nice and tiny pre & post-ringing (and VERY quiet):
Now, take a look at the filtering with ProEQ ON:
Check out the post-ringing...it falls below 0vrms everytime...and the pulse width is driving the amp a little harder. I have no clue what type of custom filtering / voodoo their doing inside with ProEQ On. It doesn't look slow roll-off, soft-knee, brick-wall or apodizing in any way.
If the rumor I started with above is true...then most folks might not hear a difference between the EQ being ON or OFF. However, if your cans have higher 'high frequency' impedance (or close to 32ohms impedance @ 20k+) then this is where it 'appears' ProEQ is delivering it's magic and greater soundstage.
Last you'll see the drop in response in mid's that I assume will mellow/warm up cans that have a very forward mid-range (i.e. like my SE535s). Maybe this is why AK has SE425 on their 'recommended' list of headphones to pair.
I'm looking for the guru's here to jump in with feedback on the above and comment. Is it possible that pairing the AK has to do more with headphone impedance response curves vs. headphone linearity?
P.S. I've got more going through it's paces on how I've seen the AK DAC handles (quite differently) based on the source file resolution....more on that later though
I just received my new AK120 and putting through some complex testing in the lab with scopes, impulse, jitter, etc. runs to see how well it performs against some of my meridian explorer, ifi idsd, e17, x5, e12diy and other portable hifi stuff.
So far I'm finding some VERY interesting results around what ProEQ and Line Out actually does, and how the internal circuitry handles conversion when it comes to their SW filters internally with the dual WM8740s.
In the meantime in my past 24h with the stock ak120, all I can say is that I'm very impressed thus far! Been using SE535 reds, SE846s and beyer t51p's. The AK is beyond expectations with SE535s even compared to the SE846 (yes, I know about the impedance issue
and even the T51s.What got me started, was a simple Q: What does the ProEQ really do? and is Line Out a SW switched Line Out?
Take a look at responses below with a dummy 32ohm load with ProEQ On vs. ProEQ Off. I've never seen such a thing before. I heard rumor that ProEQ is not truly an EQ, but rather a custom way that the AK handles the impedance changes with measured headphone frequency response. An EQ shouldn't be able to expand the frequency response all the way up into the ultrasonic range, but ProEQ seems to be doing that AND more.
Testing run dozens of times (ProEQ ON vs. ProEQ OFF):
Notice that at 20k there's nearly a 3.5db gain @ 20k ...then look into 20k+ ...I was stunned and can't replicate this on any of my other equipment.
Thinking I was crazy (which some call me)
I put the DAC in the AK through 1000s of passes on by bench.What you'll see below is a 24/192 impulse response (ProEQ OFF) showing the DAC processing normally a slow roll-off digital filter...and a great implementation at that! Nice and tiny pre & post-ringing (and VERY quiet):
Now, take a look at the filtering with ProEQ ON:
Check out the post-ringing...it falls below 0vrms everytime...and the pulse width is driving the amp a little harder. I have no clue what type of custom filtering / voodoo their doing inside with ProEQ On. It doesn't look slow roll-off, soft-knee, brick-wall or apodizing in any way.
If the rumor I started with above is true...then most folks might not hear a difference between the EQ being ON or OFF. However, if your cans have higher 'high frequency' impedance (or close to 32ohms impedance @ 20k+) then this is where it 'appears' ProEQ is delivering it's magic and greater soundstage.
Last you'll see the drop in response in mid's that I assume will mellow/warm up cans that have a very forward mid-range (i.e. like my SE535s). Maybe this is why AK has SE425 on their 'recommended' list of headphones to pair.
I'm looking for the guru's here to jump in with feedback on the above and comment. Is it possible that pairing the AK has to do more with headphone impedance response curves vs. headphone linearity?
P.S. I've got more going through it's paces on how I've seen the AK DAC handles (quite differently) based on the source file resolution....more on that later though
