CEntrance Ampersand balanced portable headphone amplifier
Jan 7, 2022 at 4:27 PM Post #3 of 125

Xinlisupreme

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Jan 10, 2022 at 3:02 AM Post #6 of 125
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Though I know it's outdated by now, I've been continuing to evaluate (i.e. enjoy) the previous 4W prototype of the Ampersand. For those of you who heard the Ampersand at CanJam SoCal 2021, it's that exact unit that I have here. This HiFi-M8 V2 + Ampersand pairing is stunningly good for a transportable rig, coming very close to some desktop gear I've heard. Indeed, for anybody not trying to crest the peaks of summit-fi, I'd even say that this makes for a pretty good main rig.

If you'll only be driving IEMs or low-impedance/high-sensitivity headphones, I'd say the Ampersand is wholly unnecessary. But if you're going to be driving anything that has a reputation of being somewhat demanding, then you're going to want the Ampersand. Though I listen at quiet to moderate volumes, there were times when the HiFi-M8 V2 just wasn't satisfying enough, especially for older tracks with lower levels.

And in case you're wondering, the headphone I've been using the most with this rig is Audeze's new LCD-5. It's a pretty resolving headphone... so if there was a flaw with either the V2 or Ampersand or both, I'm pretty sure I'd have found it by now. :smile:

That said, a lot of the above is fairly meaningless as there's a new Ampersand revision coming. Still, it's been fun evaluating this older revision so far. 😛
 
Jan 10, 2022 at 5:39 PM Post #7 of 125

mgoodman

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Hello all, thank you SDBiotek for making this thread!

Some power specs for your perusal:

13Ω: 2.3W
16Ω: 3W
22Ω: 4.4W
48Ω: 6W

All values are total per two channels.

13Ω/2.3W will result in about 120dB SPL for the Aeon Noir 2 cans. This is, generally speaking, VERY LOUD.
Either Flow C are loud. HE-6 are loud. LCD2 are unbearably loud. Susvaras are very loud. HEDD will most likely be very loud (will know soon).
So we believe this dots most of the "i's". But will let you guys be the judges.
 
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Jan 10, 2022 at 7:25 PM Post #8 of 125

ssriram2791

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Hello all, thank you SDBiotek for making this thread!

Some power specs for your perusal:

13Ω: 2.3W
16Ω: 3W
22Ω: 4.4W
48Ω: 6W

All values are total per two channels.

13Ω/2.3W will result in about 120dB SPL for the Aeon Noir 2 cans. This is, generally speaking, VERY LOUD.
Either Flow C are loud. HE-6 are loud. LCD2 are unbearably loud. Susvaras are very loud. HEDD will most likely be very loud (will know soon).
So we believe this dots most of the "i's". But will let you guys be the judges.
Fantastic ! Kudos for all the hard work !

What does the battery life look like per charge ?
 
Jan 10, 2022 at 9:20 PM Post #10 of 125

mgoodman

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Some pics below
 

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Jan 10, 2022 at 9:26 PM Post #11 of 125

ssriram2791

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Battery should be around 5 hours. Really depends on how much of heavy metal head you are :wink: We are still measuring.
Assuming low gain to high gain difference is +20 dBA, if I can operate at 50% volume medium gain and get 5 hours of it, and let my ATH-R70X sing, I am happy.
 
Jan 10, 2022 at 9:34 PM Post #12 of 125

mgoodman

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Assuming low gain to high gain difference is +20 dBA, if I can operate at 50% volume medium gain and get 5 hours of it, and let my ATH-R70X sing, I am happy.
I have a hard time believing you would need any more than that for those cans. Note that the position of gain switch and/or volume knob does not influence distortion.
 
Jan 10, 2022 at 9:45 PM Post #13 of 125

ssriram2791

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I have a hard time believing you would need any more than that for those cans. Note that the position of gain switch and/or volume knob does not influence distortion.
All I am looking for is how I can make dynamics of the headphone better with portable Class A solution, this should be fun. Hope the beta testers can shed light here on the synergy between Ampersand and some of the headphones they tested.
 
Jan 12, 2022 at 6:32 AM Post #14 of 125

caustic386

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Specs posted today. Distortion looks a little high compared to SOTA designs, would need a full sweep to be sure. If .0089% is worst case and nothing nasty hiding in multitone, shouldn't be a problem to anyone but your dog. Don't see 1ohm impedance too often these days, either, but I can't think of any headphones lower than 10ohm so shouldn't be an issue.

look at that power, though! Not sure I've ever seen that much output in such a small package - if its confirmed by independent reviewers, this thing is stunning.

https://centrance.com/ampersand/

(Scroll to bottom, click Specs)

Well done! @mgoodman I worry you have a bit of an uphill battle against the Dunning-Krueger segment of objectivists but I really like how the design prioritizes what actually matters within it's target: portability and power availability within transparent distortion thresholds.

1 Q - nominal input is 2V, if I push that harder from a abalnced source (probably around 3.5V) will distortion improve? Or will it clip?
 

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