[kyoshiro]

So I have received my new AD8620 and my AD8066 back. Noticeable difference between the 2 op amps in terms of clarity
Still gotta test the AD8620 with my HD600 and see if it still has the power to push em

 

[ClieOS]

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What rechargable battery does it use and where is a good buy to buy a spare or two?

It is li-ion and it is a generally a bad idea to buy a li-ion battery for spare unless you want to throw it into a freezer. Li-ion battery. like lead-acid and most rechargeable battery, will begin to degrade once it is manufactured. Given a li-ion battery usually lasts at least a year or two, buying a spare li-ion now means you won't use it for another year or two. By that time, you can expect a major portion of the battery capacity will have degraded away (if not destroyed by over-discharging). You can store it in a freezer (with proper packaging) to slow down the process, but the smarter way is to buy a replacement battery from JDS on a later time.
 

 

[ClieOS]

Oh, here is an updated picture of JDS family portrait.
 

 

[bluishgreen]

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But that same extra layer of depth might not be that appreciated for full sized headphone user (where soundstage is already good) or simply for those who rather prefer an upfront presentation. Instead, I would think they will find AD8620 adds a sense of hollowness to the presentation which might not be to their liking. 

 
I mainly use larger phones, and found the soundstage depth as pretty much the same as my other portable amps (Ibasso D7 & Fiio E10) however I did find the soundstage to be a little bit wider on the C421/AD8620 than the other two.  Like you alluded to, I did get the feeling of a "bigger picture" with the C421 vs my other amps, although I don't have a C421/OPA2227 to compare with.  Not sure if I'd describe it as V-shaped--maybe a bit more distinct highs, but I don't sense any emphasis on bass.
 

 

[bluishgreen]

 
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In the end I thought the difference between the two were not easily perceptible to my ears even though I had preconceptions about how I thought it was going to sound. This was tested mostly with HD25-1 II and iPhone 4S as source. Tracks ranged from 256kbps AAC to 320 kbps mp3 and 16-bit Apple Lossless.
 
YMMV

 
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Interesting!  Thanks for posting that.  I kept putting off ordering for days trying to figure out which op-amp to order.  It sounds like with similar equipment (same cans and a 4th gen iPod Touch) that there may not be a night and day difference, so that makes me feel a bit better about my choice. 

 
Yeah--that was also why I wanted to point-out before that the differences are usually "subtleties".  A lot of times in forums like these we talk quite a bit about differences in exaggerated form, which is the nature of trying to describe something in detail, but unfortunately as a side affect can lead people just starting out to think that it's like an equalizer setting with everything up on one product and everything down on another product.  It's good every once in awhile to show a frame of reference for people learning, and point-out that these differences are generally subtle (much of the time).  Not to mention the issue of actual differences vs perceived differences due to preconceptions.
 

 

[ClieOS]

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I mainly use larger phones, and found the soundstage depth as pretty much the same as my other portable amps (Ibasso D7 & Fiio E10) however I did find the soundstage to be a little bit wider on the C421/AD8620 than the other two.  Like you alluded to, I did get the feeling of a "bigger picture" with the C421 vs my other amps, although I don't have a C421/OPA2227 to compare with.  Not sure if I'd describe it as V-shaped--maybe a bit more distinct highs, but I don't sense any emphasis on bass.
 

I think it has to do with the synergy of the whole setup. I can easily tell the difference between amps using some IEM but not so much on others - thus the problem of Head-fi's discussion in general as someone's 'huge' might be another person's 'subtle' simply because the same gear is used on different setup, not to mention the how different level of perception and interpretation. It is all part of the learning to take everything we read with a grain of salt.
 

 

[JRoMan]

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I think it has to do with the synergy of the whole setup. I can easily tell the difference between amps using some IEM but not so much on others - thus the problem of Head-fi's discussion in general as someone's 'huge' might be another person's 'subtle' simply because the same gear is used on different setup, not to mention the how different level of perception and interpretation. It is all part of the learning to take everything we read with a grain of salt.
 

 
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Yeah--that was also why I wanted to point-out before that the differences are usually "subtleties".  A lot of times in forums like these we talk quite a bit about differences in exaggerated form, which is the nature of trying to describe something in detail, but unfortunately as a side affect can lead people just starting out to think that it's like an equalizer setting with everything up on one product and everything down on another product.  It's good every once in awhile to show a frame of reference for people learning, and point-out that these differences are generally subtle (much of the time).  Not to mention the issue of actual differences vs perceived differences due to preconceptions.
 

Yup. Well said, both.
 

 

[Donnyhifi]

 
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What rechargable battery does it use and where is a good buy to buy a spare or two?

I opened up the C421 and found that it uses an Apple IPOD 4G battery, super easy to find a replacement if it wears out.

 

 

[Donnyhifi]

Quote:

I think it has to do with the synergy of the whole setup. I can easily tell the difference between amps using some IEM but not so much on others - thus the problem of Head-fi's discussion in general as someone's 'huge' might be another person's 'subtle' simply because the same gear is used on different setup, not to mention the how different level of perception and interpretation. It is all part of the learning to take everything we read with a grain of salt.
 

Excellent advice, my Fitear MH334 is more sensitive but is benefiting the most with this amp whereas with the UM3X I hear much smaller gains even though it needs more power than the Fitears to attain similar volume levels.

 

[2000impreza]

Looks like the review by Headfonia is up. Not sure if I agree with the sonic differences between AD8620 and OPA2227 opamps but still a good read.
 
http://www.headfonia.com/flyin-high-jdslabs-c421/

 

[ClieOS]

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Looks like the review by Headfonia is up. Not sure if I agree with the sonic differences between AD8620 and OPA2227 opamps but still a good read.
 

Me and you, mate. I already find myself reaching an opposite conclusion on quite a few Headfonia's past amp review (especially on PA2V2, among others). Guess I'll have to disagree with his finding on AD8620 vs. OPA2227 this time as well. The impression is so different from mine that it makes me wonder if they could have received an lemon unit or not. Maybe we just have too different an interpretation on amp.

 

[shotgunshane]

ClieOS- how is transparency, dynamics and black background compared to the O2?

 

[ClieOS]

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ClieOS- how is transparency, dynamics and black background compared to the O2?

Compared to the AD860 version, everything is slightly better on the O2, and I do really mean just slightly. If you are not doing a direct ABing, you might not notice any difference at all except that the AD8620's has more depth while O2 has equal amount of depth and width. The OPA2227's version is more noticeably different because it has an upfront presentation and a richer overall tone. That being said, AD8620's sounds closer to O2 than OPA2227's.

 

[Mozu]

Me and you, mate. I already find myself reaching an opposite conclusion on quite a few Headfonia's past amp review (especially on PA2V2, among others). Guess I'll have to disagree with his finding on AD8620 vs. OPA2227 this time as well. The impression is so different from mine that it makes me wonder if they could have received an lemon unit or not. Maybe we just have too different an interpretation on amp.

I was surprised at how similar his experience with the AD8620 was to mine, actually. /shrug

 

[ClieOS]

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I was surprised at how similar his experience with the AD8620 was to mine, actually. /shrug

I posted my initial impression on C521's AD8620 vs. OPA227 a page back, in case you might be interested - here.