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new CMoy Headphone Amp build
http://diyaudioprojects.com/Forum/viewtopic.php?f=10&t=644
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Author:  Laika [ 02 Apr 2009, 11:40 ]
Post subject:  new CMoy Headphone Amp build

Hi all.

I just finished off my first amp build (I have made a few guitar effects previously) and thought I'd show it off :D ... Its a stock Cmoy except the power caps have been upped to 470's and I'm only using one 9v battery. The chip is a BB OPA2134PA. The enclosure is a Hammond 1455.

I had thought of etching a board for it but it seemed so suited to stripboard I didn't bother. Everything except the chip was bought locally, that I got from smallbearelec.com (where i buy my guitar effect parts). The two sockets with jumpers are for the optional output resistors.

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All wired up.

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A view from the rear. The battery lead is very short so the cable tie is to make it easy to remove it from the battery while in the enclosure, it also serves to hold the battery still when the cover is screwed on 8-)

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The finished amp. It works and sounds great and seems to have plenty of volume even with one battery. A slightly bigger enclosure would have been less fiddly as the in/out/pwr/vol panel is very snug but it does all fit... just

Image

Author:  Gio [ 02 Apr 2009, 17:02 ]
Post subject:  Re: new CMoy Headphone Amp build

Hi Laika, that is a fantastic job! :up:

I like the sound from the OPA opamps and the price is reasonable. Would it be ok if I add the photos to the Photo Gallery on the site?

Cheers,
Gio

Author:  Laika [ 02 Apr 2009, 19:30 ]
Post subject:  Re: new CMoy Headphone Amp build

Thanks :) ... Yeah feel free add the pic's to the gallery, I know I like checking out other peoples projects.

Author:  Gio [ 02 Apr 2009, 21:37 ]
Post subject:  Re: new CMoy Headphone Amp build

I just added it to the gallery.
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What did you think about the sound and what cans are you using with it?

Cheers

Author:  roggom [ 03 Apr 2009, 19:17 ]
Post subject:  Re: new CMoy Headphone Amp build

Great job, very neat build. Which gain did you go with?

Author:  Laika [ 04 Apr 2009, 00:22 ]
Post subject:  Re: new CMoy Headphone Amp build

gmilitano wrote:
What did you think about the sound and what cans are you using with it?

Sound is better then I expected, very transparent... nice! I've got a pair of tired Beyerdynamic DT411 that I'm about to replace with some Grado SR80i's
roggom wrote:
Great job, very neat build. Which gain did you go with?

11 according to info on the headwise site were I worked from.

Since I start work on this amp I found a local source of the 2134 op-amps and these smaller pots that would make the panel less cramped.
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I'm feeling inspired to get started on a Gainclone now :)

Author:  Gio [ 04 Apr 2009, 09:33 ]
Post subject:  Grado Headphones and CMoy Head Amp

Laika wrote:
I've got a pair of tired Beyerdynamic DT411 that I'm about to replace with some Grado SR80i's

Hi Laika, I have a pair of Grado SR80 headphones. I liked the midrange over that of the SR60, but the SR60 had better low end. See the attached Grado Headphone frequency measurements (measured by headphone.com)
Attachment:
Grado-SR60-SR80-SR125-Headphone-Frequency-Response-Plot.png

Also, depending on what you are using as a source, you may want to try a lower gain.
Cheers,
Gio

Author:  Laika [ 05 Apr 2009, 05:50 ]
Post subject:  Re: Grado Headphones and CMoy Head Amp

gmilitano wrote:
Hi Laika, I have a pair of Grado SR80 headphones. I liked the midrange over that of the SR60, but the SR60 had better low end.

Interesting .. I thought the 80's were said to have better bottom end than the 60's (just from reading comments on the web)... maybe Its a good thing I haven't ordered my new headphones just yet.... I might look at getting the 60's instead.
gmilitano wrote:
Also, depending on what you are using as a source, you may want to try a lower gain.

Yeah I had some time over the weekend to try all my various sources and the gain was a bit much so I added sockets for the gain resistors and tried a few different values. For now I've changed the gain to ~ 6x instead of 11x and this seems more useful... I will have to see how this works out when I get my new cans.

Author:  Gio [ 05 Apr 2009, 10:10 ]
Post subject:  Re: new CMoy Headphone Amp build

Hi Laika, I found that the SR60 are not as smooth as the other models in the midrange and the highend. I'm not sure how the new SR60i and SR80i are different.

If you don't need the gain, my preference was to use lower and I settled on about 4 to 6.

Author:  CrazzyAbtTubes [ 05 Apr 2009, 17:55 ]
Post subject:  2N3904 Headphone Amplifier

Nice headphone amplifier, I like how compact it is. I made one of about the same size, but does not work as well as yours and has no volume control, and not enough gain to be used for an MP3 player, which really defeats the point of it so at some point I will need to rework the circuit.

But it is the simplest amplifier on earth... only one little NPN transistor and a couple of resistors and capacitors. Just felt you may be interested in seeing it and maybe try the design for your self, all you need is a 2N3904, and it is so simple I don't even have a schematic for it. ;)
Attachment:
Mini headphone amp internals(small).jpg
Attachment:
Mini headphone amp(small).jpg

Ask me if you want to know more about the circuit...

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