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[Impression] JDS Labs C421 (OPA2227 vs. AD8620) featuring cmoyBB, O2, T5 and UHA-4. - Page 4

post #46 of 51
Thread Starter 

You might find this useful: http://www.head-fi.org/t/668238/headphones-sensitivity-impedance-required-v-i-p-amplifier-gain

 

Not a direct answer regarding your headphone, but it should give you some idea on what kind of parameters you should be looking for.

 

Don't really think the heat/current issue is correct with headphone. The power requirement on headphone is usually so small that the heat generated is negligible. With a 600ohm headphone, the current needed is also less demanding than, say, a 12ohm headphone. It is not the same compared to speaker.

post #47 of 51

I read the graph, and different pairs draw such different numbers like this one

 

Audio Technica ATH-ANC7B 118 305 0.398 1.305 0.52 -14

compared to this one

Hifiman

HE-6 89 43 11.22 260.935 2927.734

15

post #48 of 51
Thread Starter 

It is not about individual headphone, but overall trend. If you look closely, you will see in many cases, high impedance headphone often requires higher voltage swing and lesser current draw than low impedance headphone.

 

Also, HE-6 is a bad example for you to look at, as it is planar magnetic and not dynamic. You simply can't compare apple to orange.

post #49 of 51
Quote:
Originally Posted by ClieOS View Post
 

It is not about individual headphone, but overall trend. If you look closely, you will see in many cases, high impedance headphone often requires higher voltage swing and lesser current draw than low impedance headphone.

 

Also, HE-6 is a bad example for you to look at, as it is planar magnetic and not dynamic. You simply can't compare apple to orange.

Ok yeah that one threw me, and didnt seem to fit the otherwise noticeable trend

post #50 of 51
My Studio V / JDS C421 rig.


I use this for driving full-size headphones mostly, with the likes of:  SHR440, ATH-M50, Klipsch Image One, MDR-V6.


Switching to 'high gain' it will drive 250ohm DT880 without any fuss. 



Edited by H20Fidelity - 6/2/14 at 6:51am
post #51 of 51


I just picked one of these guys up on the used market for a song. Reading the OPs original review was impressive to me. When I saw this amp company's products recommended on Head-Fi to drive the AKG k701s my jaw dropped. Actually if I was outside a small fly could have quickly flown in.biggrin.gif

Upon spending a couple days with it, I'm quietly amazed. I was looking for an amp to take with me around the house and into the yard with full size headphones. I know, I'm strange. But having a really small amp and DAC/file player and being able to walk around with great sound is of value to me.


I really can't add anything to the review on page one as it being so complete. I want to thank ClieOS for his PM about charging style, battery life and battery replacement.

So this amp does run the k701s to a point. I was listening to the Beatles " Here Comes The Sun " in Apple lossless with an iPod Classic and Fiio LOD and it was maybe just there in the volume dept. Mind you these little portable amps are not suppose to even come close to running a beast like the k701s and most readers here would see it as an exercise in futility. Obviously this little amp has way enough power for a lot of headphones out there. I'm primarily using it with full size Denon AH-D 7000 headphones. The 7000s are actually easy to drive and even though I have other amps which drive them better I just don't have extension cords that long or the interest to use them around water. Lol

My normal modus operandi is straight out of an iPod Touch 5 gen. So even though the JDS c421 is noted at ruler flat line transparency in the frequency response dept., I believe the iPods to be even a little more ruler flat. That said the JDS adds a tiny warmth to the combination that is an added surprise. That along with getting the added power to make the bass respond with more authority while using full size AH-D 7000s.

I'm sure added juice in the 5C newer model amp would benefit any asylum members attempting to drive the k701s. For the price and what I'm doing things are fine.



The 8620 chip dug it's way into my very rare and sonically demanding Pete Namlook & Klaus Shulze Feat Bill Laswell test CD. Most members use DSOTM I use The Dark Side Of The Moog VII.

Here. http://m.youtube.com/watch?v=5mHlBNIPTz0



I gotta say it's the way this handles the mids that makes the magic. Added the bass detail from such a funny little box the size of a pack of cigs. The great part is it is the most dead silent amp I own. Those magnets! I wish I had magnets to silence the hiss from my Wife.
Edited by Redcarmoose - 6/16/14 at 6:24pm
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Head-Fi.org › Forums › Equipment Forums › Portable Headphone Amps › [Impression] JDS Labs C421 (OPA2227 vs. AD8620) featuring cmoyBB, O2, T5 and UHA-4.