FS: CMoy Headphone Amplifier

Up for sale is a portable CMOY headphone amplifier built by "mgproaudio" (Mike Gaspa http://feedback.ebay.com/ws/eBayISAP...394858&frm=284) on Ebay. The operational amplifier chip is the BurrBrown OPA2227. The power caps used are the Cornell Dubilier SMD 1000uF to provide excellent bass response. The headphone jacks are gold plated Kobiconn Surface Mount style jacks. It has a rocker-style switch and a BLUE LED. There is no bulky volume control (why bother when you can adjust volume from your player). The gain on this one is set to moderate-high and is best used with higher impedance, power hungry headphones (60+ Ohms). It is powered by a single 9V battery and is about the size of a credit-card, so it is ultra-portable.

$35 shipped

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My feedback:
HEATWARE: http://www.heatware.com/eval.php?id=43019
EBAY: http://feedback.ebay.com/ws/eBayISAP...d=prona13&iid=

ttt

How long will it run on a 9v when left on 24x7? Option for an external wall wart for power? I guess I could notch the battery cover and use one of the 9v wall warts with the 9v battery connector but that's not a terribly elegant solution. USB power would be a damn nifty solution - maybe I could mod an old USB cell phone charging cable. Also - are you installing a blue LED on all of them now? Sorry for all the questions.

My intended use is for a Sony all in one PC (like this one - funny amazon says monitor sold separatley - the monitor IS the computer - it's our kitchen PC)
http://www.amazon.com/gp/product/B00...lance&n=541966
which has a unusually low speaker level output that coupled with the fact that I am running it on an cable to a stereo extended roughly 25 feet leaves the level very low at the stereo and trying to compensate by cranking the stereo louder just introduces distortion.

Please note: I'm not the builder of this amplifier, so I can not customize the amplifier to your needs. I bought this from a professional (mgproaudio) on EBay. If you want anything added on to this amplifier, you're going to have to go through him. I've tested it to see how long it runs continuously on a 9V. I use it on and off. I also use rechargeable 9V batteries, so runtime is not too much of a concern for me (as I always pack an extra).

Yes you could run it off the wall ONLY if you have a REGULATED adapter (something that will put out a CONSTANT 9v). The cheapo switching AC-DC adapters won't do. USB could work but since that would only be 5V, you wouldn't get the same performance as you would out of a 9V battery.

Also, beware that this is mainly for the purpose of amplifying a signal to drive some of the higher-end current-hungry headphones (high end Sennheiser, Grados, AKGs, Beyers, etc...). And as an amplifier, hooking it up to a low-end SOURCE will amplify any low-end features such as distortions or noise. And as a portable amplifier, it is mainly targeted towards people with portable media players (Ipods, Zens, CD Players, etc...).

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I'm open to any sort of offers, guys.

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ttt

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How long does the battery last under normal use? If I put in a fresh battery, would I be ok for a day of pretty constant listening?

What happens if this is used with lower impedance headphones? ie 32 Ohm or 16 Ohm?

Yes, it should last a day or so (12+ hours) with continuous play. Using it with lower impedance headphones, it will definitely drive it fine, but make sure you lower your volumes, since the gain is high. Also, there could be a slightly amplified hiss due to the lower impedance of your headphones. I primarily use this with my Koss KSC-75 (60Ohm). I've used it with my old pair of Sennheiser HD280 Pro's (64Ohm) and it was great. Much better bass impact.

bump still available.

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price has now gone to 35 shipped!!!

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To all that are interested in this customized version of the Cmoy Headphone Amplfier. I am the creator & builder of this powerful little amp. I see questions posted regarding battery life.

Battery life really changes based on your usage. It can range from 12 hrs to 12-20 days, The higher load your phones are putting on it, the shorter the battery life. This amp does very well with the higher impedance phones 60 on up to 600. 300 & up, I suggest a 12 volt DC adapter to drive this amp properly. If anyone has questions, feel free to email me: michael_gaspa@msn.com

What kind of difference would I see using this with some Senn 497's?

Try heading over to www.headfi.org

Bass impact on my KSC-75's and my Shure E2c's went up. If your headphone is power hungry and lacking in power, they may benefit more than headphones that are easy to drive.

http://www.headphonereviews.org/head...headphoneId=84

The HD497 apparently has been reviewed by one individual, and it was found that on a scale of 0-10, the improvement with amplification is a 6. I'm thinking (according to that) that there should be some noticeable improvement.

I'm interested in it and I sent you a private message with some questions as well.