My DIY CMoy Headphone Amplifier

[vivek.saikia]

Hi All,

I finally attempted a DIY headphone amplifier and to start with I chose the CMoy amplifier, being the simplest headphone amplifier around.
The CMoy amplifier is well know for very low distortion (~0.001), good quality amplification and simple/cheap design.

I ordered the kit from electricsumo on ebay.com from the below link:-
Banzai V2 CMOY Headphone Amplifier DIY Kit PCB Amp HiFi | eBay

The parcel arrived from Thailand and reached my place in about two weeks.
I specifically chose this seller as it was providing some good quality components in the kit, like Elna capacitors, machined DIP socket etc.

The installation of the kit was quite easy and i completed the soldering in about 30 mins time. Although, the connection of the capacitors and the power cable was a bit of problematic as it involved soldering the capacitor and the power cables to one hole only and I overcome it by using the reserve holes on the PCB just to avoid soldering multiple components in a single hole. If the PCB can be modified to add additional holes to accommodate multiple components in a single hole would make the job easier for the newbies.

After all the soldering work was done, I connected the battery to the amplifier and I was relieved to see the LED lighting up without any fumes.
I fed the amplifier the headphone out of my laptop and connected my Koss Porta pro to the amplifier.
After listening to the amplifier for merely 2 mins, I could tell the significant improvement in the sound quality. The instrument separation was something which I could make out immediately. The bass was tight and well defined. After that I switched to my ME Electronics SP51P with the balanced port on.
The sound quality just bowled me over. The sound was so well defined and balanced. The clarity had improved multifold compared to the headphone out from the laptop. I kept the laptop volume to low so that no distortion is injected from the source. The CMoy amp amplified everything so honestly whatever was coming from the laptop output, even the noise from the laptop. yes, for the first time I realized how noisy the earphone out of my laptop was! I tested and confirm that the noise was not generated from the CMoy amplifier by disconnecting the input from the amplifier and increasing the volume in the amplifier. Even at maximum volume, I could not hear any noise and the amp was dead silent. so, this calls for improving my source, maybe adding a DAC to act as a source to the amplifier.
For the time being, I could say that I have achieved in the sound quality I was longing for and would not need an upgrade for many more years to come.

As for the casing of the amplifier, I was planning to put the amp PCB and the two 9V battery inside the Altoid tin box (as the whole world is doing), but I realized that this would result in a very cramped box. So maybe i will use a project box from Radioshack and put everything inside it or else you guys can suggest me some nice enclosure options.

 

[santhosh]

Thanks for sharing Vivek. What do you plan to use as an enclosure for the board? Another Altoids box?

That Altoids Box is a good idea. I see that it is not part of the kit. Where did you source yours from? I need one for my CNC Phonostage.


Sent from my iPhone using Tapatalk

 

[vivek.saikia]

Thanks for sharing Vivek. What do you plan to use as an enclosure for the board? Another Altoids box?

That Altoids Box is a good idea. I see that it is not part of the kit. Where did you source yours from? I need one for my CNC Phonostage.


Sent from my iPhone using Tapatalk

As of now I am thinking of using a project box from Radioshack as below:

Project Enclosure (4x2x1") - RadioShack.com

But considering the (good) quality of the amp, I may spend some more money on the beatification of the enclosure, as I will be using this amp very often.

The Altoid box is not a part of the kit and I had to eat a whole box of mint to empty the box hyeah:

 

[sachu888]

Thanks for sharing Vivek. What do you plan to use as an enclosure for the board? Another Altoids box?

That Altoids Box is a good idea. I see that it is not part of the kit. Where did you source yours from? I need one for my CNC Phonostage.


Sent from my iPhone using Tapatalk

Hi Santhosh,
I am using this Aluminium enclosure for my CNC.HAMMOND|1455N1602|ENCLOSURE, CLEAR, BLACK END PLATE | element14 India

Regards,
Sachin

 

[kaushik]

That was great build congrates, Cheap Am radio box Cabbie can be used ,no need of import.Import only if u get the hammond aluminum boxes for less.

i was eyeing on that a while besides glorified JRC did not like some things

- batteries make heavy , buying or charging 2 cells is hassle
- JRC op amp has more bass but less Q than many new variants
like AD and TLE series
- (this is my opinion ),HP plugged to altroids tin looks like school kids toy


so i came with cute rail splitter circuit for voltage and feeding a real good AD series Opamp[look for my cmoy thread among old threads]

But my op amp needed 4.5V+- all the time , rail splitter cant maintain that from just 9v so finally solved that using

[9V rechargable]+[2.7V slim lithium from china mp3 player]

Sound was real good ,just did not box it

 

[vivek.saikia]

That was great build congrates, Cheap Am radio box Cabbie can be used ,no need of import.Import only if u get the hammond aluminum boxes for less.

i was eyeing on that a while besides glorified JRC did not like some things

- batteries make heavy , buying or charging 2 cells is hassle
- JRC op amp has more bass but less Q than many new variants
like AD and TLE series
- (this is my opinion ),HP plugged to altroids tin looks like school kids toy


so i came with cute rail splitter circuit for voltage and feeding a real good AD series Opamp[look for my cmoy thread among old threads]

But my op amp needed 4.5V+- all the time , rail splitter cant maintain that from just 9v so finally solved that using

[9V rechargable]+[2.7V slim lithium from china mp3 player]

Sound was real good ,just did not box it

Thanks for your input.
Once I "box" the amp, I will try out different OPAmps in this circuit and maybe also add an external power supply option to it. I hear that the Japan Radio OpAmps are not much highly regarded. I will try out the OPA2227 on this circuit later on.

I have just ordered the below ABS plastic Hammonds enclosure from Mouser.com -

1553BTBUBK Hammond Manufacturing Enclosures, Boxes, & Cases

I found it really portable and mobile in comparison to the extruded aluminium enclosures.

As I am in the US, I don't have to worry about the customs anymore :licklips:

 

[spirovious]

Good work Vivek,congrats.

 

[sunilj]

Vivek, nice one. I see the dual 9V, similar to one I made from here. It chews 2x9V cells like I eat chocolate. Glorious sound, WOW, so I can imagine your trip.

Good going.

 

[vivek.saikia]

Vivek, nice one. I see the dual 9V, similar to one I made from here. It chews 2x9V cells like I eat chocolate. Glorious sound, WOW, so I can imagine your trip.

Good going.

I haven't got enough time to drain down the battery listening to music, but I feel the dual batteries should last long.
I totally agree on the sound quality. I now know why people claim "listening things I have never heard before". I have heard the breath of Jagjit Singh while he sings "Kal Choudhwee ki raat thi"!! Amazing!!
Only thing which I would like to improve is my source now and after the success of my CMoy build, maybe a (DIY) DAC is on it's way :clapping:

 

[hydra]

Great work, Vivek! Congrats!

I use a cMoy with my ancient iPod (via LOD) myself when I travel. I didn't build it of course (wish I could ). I'd bought it off eBay (BSG cMoy with OPA2227) a couple of years back. It is a very nice sounding amp, especially considering how little it costs to build. Mine is in a plain Altoids tin, and uses a single 9V battery, that lasts for about 12 hours of use.

 

[kaushik]

vivek try TLE series , in 128 Rs they sell great stuff... recharge option is way to go..if u keep at desk u could have made desk amps

The DIY Grado HP amp clones are better things to try ..Cmoy has got many variants , waiting for people who will do one of the next level hp amps

glassjar audio kits are also very good

 

[linuxguru]

vivek try TLE series , in 128 Rs they sell great stuff... recharge option is way to go..

You probably need to look for low-voltage RRIO (Rail-to-Rail Input/Output) opamps with low quiescent current. There aren't too many choices of good RRIO opamps available locally, but one possible choice is the NatSemi LM6152, which is specified down to +/- 1.35V operation, or single rail +2.7V operation.

 

[kaushik]

linuxguru,
low quiescent current for battery life ? that is not very important as one 9V and tiny 3.7v lithium guys will do a good 6hour+
+/- 1.35V operation will be just wow , i am a noob it can be powered with 3.7v lithiums with that using rail splitter?

I will sit with these stuff some day .

 

[keith_correa]

Now that you have wet your whistle - go to the highest level. Do the O2. Wait for a DIYA GB. One just concluded. But you can try your luck - ask if anyone has backed out and you can be squeezed in instead.

 

[doors666]

there is also a guy selling pre-built o2 kits on diyaudio gb.

 

[vivek.saikia]

I have done a bit of beautification of my headphone amp by putting it in an enclosure from Hammonds.

Below are some eye candies

 

[sachu888]

Looks great

Regards,
Sachin

 

[keith_correa]

I have done a bit of beautification of my headphone amp by putting it in an enclosure from Hammonds.

Below are some eye candies

Nice! Nicer! Nicest!

 

[kaushik]

cool sporty !

 

[vivek.saikia]

After the completion of my headphone amplifier, I am scouting for some good USB DAC kit which is simple to build and have some decent sound output (compared to the laptop's headphone out).
I have come across this grubDAC kit from beezar.com which has some good testimonials in various audio forums.

Have anyone heard this DAC or has any other suggestions?

The following in-cable option looks quite good to me: