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JDS Labs cMoyBB V.2.03 vs. Epiphany Acoustics EHP-02

post #1 of 44
Thread Starter 

JDS Labs cMoyBB v.2.03 compared to the Epiphany Acoustics EHP-O2

 

To start of with these are both amplifiers designed for the portable market and both have very attractive low prices. They are currently the only two that i own and have ever owned and if i ever acquire more i may well add them to the the comparison.

 

The cmoy is a commonly used open source design for budget headphone amplifiers and are name after the inventor Chu Moy. However although they may all look similar the performance is all down to the op-amp that is on the circuit board and these can also be interchanged. This one is sold at roughly £45 delivered to the UK and a little more for the chargeable one.

 

The EHP-O2 or the objective 2 is also an open source design created by nwavguy. It was to prove that cheap amplifiers bout preform with some of the more expensive ones and is manufactured by both JDS Labs and Epiphany acoustics.

 

I must also that the customer service of both these manufactures is absolutely top notch and they always respond to email asap an help resolve any problems you have!

 

For this review i will cover us much as i can, sorry if it drags on, and i will try and make it as exciting as possible. I hope you enjoy it  !

 

cMoyBB Overview:

  • Volume Knob
  • 3.5mm Input
  • 3.5mm Output
  • Optional AC Charging 
  • Bass Boost
  • Iconic Altoids Casing

 

IMG_1118.JPG

 

Altoids Tin Casing

 

 

IMG_1120.JPG

Input and output as well as volume control

 

IMG_1121.JPG

 

Circuit board inside. Small black switch inside is the optional bass boost.

 

Epiphany Acoustics EHP-02 Overview

  • AC Power Supply Included
  • On/Off Button
  • 3.5mm Output
  • Volume Control
  • Gain Switch (can add 3 decibels)
  • 3.5mm Input

IMG_1125.jpg

 

Faceplate and front of the o2

 

Build Quality and Portability

 

cMoy


The construction is great with with all the craftsmanship done flawlessly with nothing loose or looking out of place. So far i have had no problems with the casing in the 3 months i have owned it and although you have to remember that is is the casing of a £1 pack of mints i think it does just great. The only thing, if anything, i feel is that the lids connection to the main case feels a bit flimsy when you excessively opening or closing (when comparing bass boost on and off). It is all metal made, hinges casing and the volume control. The volume control also works as an on and off switch which you click to the right on. This work great and feels strong and clunky but the attachment seems like it may have future problems as its attachment seems to be fairly weak looking. 

 

Portability wise it is great at just under 4 inches in length, 2 and half inches across and an inch of depth it can easily be strapped to your player or sit comfortably next to you player on the go. It is obviously suited to be carried around as the casings original duty was to carry mints around for a person. It is also fairly lightweight (maybe just a bit heavier than my iPhone  4, but not by much) and is not going to cause problems to carry or weigh down your pocket.

 

The design is also great and is also in a sense customizable as you can request tin colour casing as well as the colour of the LED light which show it is on (my one is blue). It has quite a unique as well as iconic and cool design because of the alto ids case which can be also quite novel with non-headphone enthusiasts friends. The design is also all quite simple and their is nothing out to confuse the user with the circuit board labeled inside with what everything is.

 

O2

 

This is a solidly built piece of equipment which looks like it can take a punch or two. It looks like their has been a lot of time spent perfecting it and making sure their and now build issues. It is all metal casing and everything but the input and output socket and the on/off and gain switch, which are plastic, is also metal. The volume control is perhaps a smaller knob than on the cmoy but its has a better, more reliable feel to it. It seems to be made up of two parts the faceplate and then the rest of the as their are four screws that attach the two pieces, this is all done well as their is no gaps or unevenness. The only fault with the built quality is the inputs and outputs as their is a little struggle for me removing the jacks of my inter connect and headphones. This feels like it could end up being quite problematic and it makes me feel slightly on edge when taking my headphones out. It could defiantly be a lot smoother of a process.

 

Now this is marketed as a portable amp and this i do not get. I am alright with this as it is not intended for portable use but i don't even think i will ever leave the house with it. I am saying this because of both the size and weight of this amp. It is 3 inches in length and 5 inches in width with a depth of 1 and half inches roughly and this size is not really suited for pocket carrying. The next issue is the weight which is a good 3 times the weight of an iPhone 4 which could really cause a strain on however your carrying. So in other words it is suited for desktop and home use with the features of a portable amp(3.5mm input and output).

 

Comparison

 

Build Quality

 

cMoy 7/10

O2     9/10

 

The O2 is better in the fact that it is all encased and is defiantly made out of a better metal and the hinges just are not as sturdy enough. The craftsmanship is great in the both build of the O2 is just beautiful and you can see the time has been spending making it perfect. At the end of the day it is a £1 tin against a hand crafted casing.

 

Portability

 

cMoy 9/10

O2     2/10

 

No competition hear which has been quite simply justified above.

 

 

 

Driving Capabilities

 

They way this works is the out put impedance of the amp should be no less (in most cases) than an 8th of the headphones.

 

cMoy


This does extremely well.  It copes more than fine when driving the 300 ohms impedance Sennheiser HD580 which is one off the more power hungry headphones out their! As i am aware their original purpose was to drive high powered headphones cheaply and these will do most headphones I'm sure. Obviously if these are for portable use then their should be nothing that even causes them a problem as most earphones have an impedance of 16 ohms to 50 ohms and these will cope just fine even with the ridiculous impedance of the 150 ohms hifiman re262!

 

O2

These don't do as well as i thought they would if i am honest. They have an output impedance of 0.5 ohms meaning that they should be fine with anything over 4 ohms headphones which basically means anything. This all being said they still do not do bad. When using my iPhone 4 as a source connected with my Fiio LOD my HD580s are driven fine with no need for the additional gain option (adds 3DB). However it is a different story when using iTunes on my mac. Even on top volume without gain on it is depressingly quiet and then when you add the gain it is a listenable volume at half way but if you want anymore volume it kills sound quality completely. I also feel although maybe just my head playing with me that it does not sound as good when using the gain. That being said maybe something is playing up on mac as i even needed gain to get listenable volume out of my 32 ohms impedance superlux HD681 which are actually made quitter by the amp than directly from my mac, confusing. Everything else from my phone they are doing wonders with and also my in ears from my mac are going down a treat which is all good.

 

Comaprison

 

From iPhone 4

cMoy 10/10

O2     10/10

 

From iMac

 

cMoy 9/10

O2 8/10

 

From iPhone 4 their is nothing wrong with either but i think that the cMoy just clinches it when driving from iMac just because of the fact i have to use gain with low impedance headphone such as the superluxes.

 

Sound Quality


To do this i will be doing the main listening through my sennheiser HD580s as that was the purpose of the amplifiers. The music will be in flac on my iMac.

 

Bass

 

cMoy

 

The cmoy has two bass settings with either the bass boost on and off. So starting (HD580s) without the bass boost the cmoy has already got for most people enough bass. Not bass head amounts but slightly more than the headphones unamped and the outcome is not bad. It is fairly tight and controlled which leaves it giving you an ok impact but not the sort of impact that you really feel. It lack decay and it sort of comes and go's. It adds maybe the teeniest of bit of extension to the headphones which is already quite good so that is nice but nothing special. All that being said its ok and i might being harsh to it as it does not help that i am a/bing it with the superior O2. For its price it does do a good job for sure. 

 

Now time to turn the bass boost on! You are flooded by a sea of loose flabby bass that leaks straight into the midrange. It loses all sense of detail and sort of just booms anything with a low frequency out the earphones. You also lose extension and it does not reach down to pick up up bass but sort of just amplify whats their. Personally i think its horrible and never use the feature even on my earphones that lack a bit of bass. If your bass head and just want pure quantity off bass and are not bothered about quality then your gonna love this. I reckon this could turn a £10 pair of earphones into something with slightly better and definitely more bass than any image seeking bass trumps all beats by dre fan could ever get out of any of the beats line.

 

Note: When i had my Fischer Audio DBA-02s on the way i had read that they could do with a tad more bass and i already had this and i thought they were going to be a match made in heaven but i was completely wrong and the amp seemed to just muddle up the DBA's and everything sounded awful. I have read that some balanced armature earphones respond bad to amping so maybe this was the case but then again i absolutely love the pairing of the Shure SE420s with the cmoy. All IMO of course.

 

O2

 

Now i like the bass on the HD580s a lot and now well i just love it. It adds bass quantity to the headphones, more than cmoy but nowhere near the ridiculous amount foo the bass boost, and it just seems to work. The extension is great offering additional details that the HD580s can not offer with the cmoy and amp less. I would also say that the bass is more forward on the O2 than on the cmoy, by just a tad, which offered an overall warmer sound signature to the headphones. But to sum for bass this works!

 

Comparison

 

Quantity

cMoy Normal

7/10

 

cMoy Bass Boost

12/10

 

O2

8.5/10

 

Quality

cMoy Normal

7.5/10

 

cMoy Bass Boost

4/10

 

O2

9/10

 

Midrange

 

This took some think as although both amps perform different in the mids i could not put my finger on how to explain the difference but here goes.

 

cMoy

 

The mids are well.... Smooth but oh so thin and are really lacking texture. They flow really quite nicely and have a breezy crisp feel in them. But they just feel like their lacking something like your not quite getting the full picture that you get with O2. The mids are also slightly recessed giving off a slightly U-Shaped sound signature. The vocals are very airy but seem to be hiding and are the opposite of some in you face forward mid headphones. I guess they sound whispered.

 

O2

 

Okay so the reason that the cmoy could feel so thin maybe that these mids have a rounded fullness to them. Their is a balanced feel to them which is supported by the way the background percussion sort of synchronises with the main instrument and vocals. Its an effect i am defiantly feeling and i may have put it across wrong but thats how my ears are taking it. Its attention to detail is also good and i am not really differentiating that much to the cmoy. Now moving on to vocals and this can represent male voices so liquidly smooth and lush its quite surreal. Listening now to Foo Fighters Dave Grohl singing the acoustic version of overlong is what i can only imagine a (male) angel sounds like and it does not stop their. Moving on to Slipknots Vermillion pt.2 and Corey Taylors voice has a husk to it that just sounds phenomenal. Female voice is not as notable as awesome but the amp still does a good job.

 

Comparison

 

cMoy

8/10

 

O2

9.5/10

 

Treble

This is probably the biggest difference between the two amps and really creates different sound signatures between them.

 

cMoy

 

The cmoys treble is packed with a sparkle that completes the cmoy with a bright sound signature. They have an effect that is really quite present and it is very glistening. Synth effects have a real ping to them and pianos have a glow to them. The presence of it i would even compare to my DBA's! The detail is also good, But far from the standard of my DBA's, but the lack of detail gives a bit of a fun feel.

 

O2

 

So same sparkly treble that the cmoy gave? Quite simply no. The highs are really quite laid back and although they extend as far as the cmoy they could not sound anymore different. That being said they are more detailed and accurate. Depending on what you like or even what mood your in could effect preference here. You want some casual listening to some chilled out song although the O2 is overall better i might just get the cmoy out for it fun sparkly treble.

 

Comparison

 

cMoy

8.5/10

 

O2

8/10

 

Soundstage

 

Not gonna right to much here and the HD580s have an amazing soundstage to start with but the O2 gives it a more three dimensional feel and expansion and causes the cmoy to feel canned in after. 

 

Overall

 

Quite simply the O2 is in a different league but thats not to say that cmoy is not a great piece of equipment. In fact i was in love with the cmoy before the O2 came and still am but the O2 just brings up a bucket load of faults that the cmoy does have. You also have to remember although they are both cheap pieces of equipment they O2 is double the price off the cmoy so you would expect it to out perform it. So two great amps which are both an easy 10 for value. I would love to hear an expensive desktop amp as I'm sure that the O2 could give it a great little run for its money although then again i could be surprised!

 

Disclaimer: This is all in my opinion and is how i heard it with the music i am listening to and is all based on my experience with the Sennheiser HD580 headphones. I have also exaggerated parts of the sound quality part so that that is clear to understand what i am hearing so take it also with a grain of salt.

 

Thanks for reading and i really hope you enjoyed.

 

Note: i also wanted to get this online quick so i will edit in comparison with some songs from different genres and take you through the songs with each amplifier.

 

 

 

 

 

 

 

 

 

 

 

 


Here is how i felt about the O2 paired with the aurisonics ASG-1! (Transferred from ASG-1 Thread)

The first thing that stands out as being improved is the thicker texture that adds a layer of depth to it which is a very welcome improvement! It also increases the soundstage in width not height and these iems have quite a thing and tall soundstage so this is is quite noticeable and makes the instruments feel better presented and more spread out!

As well as that the mids feel ever so slightly smoother!

Nothing else other than but i think it is a welcome improvement! Shame that its too hard to lug the O2 around with me :L


Edited by Swimsonny - 6/22/12 at 6:22am
post #2 of 44

Nice review! If I wasn't on a DAP and mid-fi headphone buying spree, I'd probably pick one up for myself.

post #3 of 44
Thread Starter 
Quote:
Originally Posted by ssrock64 View Post

Nice review! If I wasn't on a DAP and mid-fi headphone buying spree, I'd probably pick one up for myself.


Ive been on a mid-tier headphone and amp spree (similar to you) but have just stuck with my iPhone 4. Am seriously considering a Cowon J3 though!
post #4 of 44
Thread Starter 
Ok not quite so similar to you (you've got quite a few more phones!)
post #5 of 44
Quote:

Originally Posted by Swimsonny View Post
 

Driving Capabilities

 

They way this works is the out put impedance of the amp should be no less (in most cases) than an 8th of the headphones.

 

Actually, it is the other way around, it should be at most 1/8th of the impedance of the headphones, so for an amplifier with an output impedance of 25 Ohms, a headphone of at least 200 Ohms is recommended. But a smaller ratio is not necessarily a problem in practice, it depends on the headphones how much the sound changes with a particular damping factor.

The O2 has an output impedance of about 0.5 Ohms, not 33. This also makes the correct interpretation of the above rule obvious, otherwise it could not drive anything above 4 Ohms. normal_smile%20.gif

 

post #6 of 44
Quote:
Originally Posted by stv014 View Post

The O2 has an output impedance of about 0.5 Ohms, not 33. This also makes the correct interpretation of the above rule obvious, otherwise it could not drive anything above 4 Ohms. normal_smile%20.gif

 


I'll venture a guess and think may be the OP has mistaken the listed output power over a 33 ohm load (on Epiphany Acoustics' website) as output power with a 33 ohm output impedance.

 

post #7 of 44
Thread Starter 
Thank your for pointing out my mistake and What your saying is that the output power (accident called that impedance) is meant to be ideally at least an 1/8 of the impedance of the headphone? (am I correct here?). So this is ideal for 264ohms and above headphones? I will correct my terminology as soon as I get home and on the computer. Thank you for pointing out my mistake and I would be happy if anyone lets me know if I have done anything wrong!
Edited by Swimsonny - 3/17/12 at 9:00am
post #8 of 44

No, the 1/8 rule says that the output impedance of the amp should be at most 1/8 of the headphone impedance to have a desired damping effect, i.e. for a 32 ohm headphone, you should use an amp that has an output impedance of 32/8 = 4 ohm or less. For 16 ohm headphone, the amp's output impedance should be 16/8 = 2 ohm at most.

 

Also, as stated by stv014, the actual output impedance of O2 is around 0.5 ohm - so by the 1/8 rule, it can drive headphone with impedance 0.5 x 8 = 4 ohm and above without any damping issue.

post #9 of 44
Thread Starter 
So is their an 1/8 rule which I have got confused or am I speaking gibberish? At least I am learning!
post #10 of 44
Quote:
Originally Posted by Swimsonny View Post

So is their an 1/8 rule which I have got confused or am I speaking gibberish? At least I am learning!

 

Basically, the "no less" in this quote from your review needs to be replaced with "no more":

  "They way this works is the out put impedance of the amp should be no less (in most cases) than an 8th of the headphones."

 

post #11 of 44
Thread Starter 
Thanks a lot mate I will give these a read! Over than the mentioned hiccup how did you think it was?

Just edited the post so that it should ow be all correct. If anyone know the independence of the op-amp used in the the texas instruments OPA2227 then i will be grateful as that i what is in the cMoy. I may have been right with the original 25 ohms as i got that off a massive specifications sheet a while back and that would explain why it does not like the pairing with the low impedance DBA-02?
Edited by Swimsonny - 3/17/12 at 11:50am
post #12 of 44

Hmm? CmoyBB also has less than 1 ohm on output impedance. OPA2227 has nothing to do with it.

post #13 of 44
Quote:
Originally Posted by Swimsonny View Post

Ok not quite so similar to you (you've got quite a few more phones!)


Trust me, you'll get there. A year ago, when I purchased my ATH-M50, I'd have never expected to have and hoard so much equipment by now. My list on Head-Fi is not even 3/4 of what I have.

post #14 of 44
Thread Starter 
Quote:
Originally Posted by ClieOS View Post

Hmm? CmoyBB also has less than 1 ohm on output impedance. OPA2227 has nothing to do with it.


Oh alright it was only as on jds labs site on specs it said impedance = impedance of op-amp! Ok thanks for you help and I think it's all sorted now
post #15 of 44

Not sure how the SQ goes from the CMOYs treble to the O2's 'laid-back mids' - you lost me there. 

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