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Is This CMOY Amp and Crossfeed Circuit Any Good?

post #1 of 10
Thread Starter 

Hi, Sun Jigglet here.

I'm looking into purchasing a $50 CMOY amplifier on ebay (the ones built by "ampedup77", in particular), and I was wondering if they are well-built/ of acceptable quality.
Here's the link: http://www.ebay.com/itm/18V-CMOY-RA1-JRC4556-Headphone-Amplifier-Tiger-Perfect-for-Grado-Sennheiser-/170841459592?pt=LH_DefaultDomain_0&hash=item27c6f1cb88#ht_3997wt_1185

I'm also looking into the crossfeed circuit "ampedup77" is selling (Link: http://www.ebay.com/itm/Natural-Sounding-Crossfeed-for-CMOY-Or-Any-Other-Headphone-Amplifier-/170841158243?pt=LH_DefaultDomain_0&hash=item27c6ed3263#ht_500wt_1202 ). Could I get some opinions on these as well?

If anyone has had experience with "ampedup77"'s CMOYs (and/or the crossfeed circuitry), please do tell me about your opinions as they are much appreciated. Any tips and opinions on CMOYs (or portable headphone amplifiers in general) and crossfeed would be equally appreciated..... Educate the newbie! smily_headphones1.gif 




* Please try to focus on sound quality and build quality/durability for now. Thank you!

** I do have some questions regarding the CMOYs sound.. do they (in general) have a bias a certain area? Are the focused on the lows, the mids, or the highs? How do they fare with the Porta Pros (I'm looking into these popular phones as well)?

*** Can the mentioned crossfeed circuitry work (sufficiently/ in a satisfying way) without amplifiers?


edit1= Found out the CMOY amp I was looking at wasn't $20 after all (it was on an auction)! "ampedup77" is selling the same CMOY for $50 on immediate purchases. I editted the CMOY ebay link and "around $20" to "aound $50".

 

edit2= Would these ( http://www.ebay.com/itm/18V-Cmoy-portable-headphone-Amplifier-Audiophile-Sound-Cool-Stuff-All-Accessory/110878819663?ssPageName=WDVW&rd=1&ih=001&category=112529&cmd=ViewItem#ht_500wt_1202 ), and these ( http://www.ebay.com/itm/Cmoy-Classic-Headphone-Amplifier-Texas-Instruments-NE5532-variable-gain-Red-tin-/190641325342?pt=AU_Electronics_Audio_Amplifiers&hash=item2c631bc51e#ht_3729wt_1143 ), and these ( http://www.ebay.com/itm/Bass-enhanced-Natural-CROSSFEED-Acoustic-Simulator-for-CMOY-headphone-amplifiers-/190657483815?pt=AU_headphone&hash=item2c64125427#ht_3035wt_1139 ) be any good?

+ Added ***


Edited by sunjigglet - 5/12/12 at 11:43pm
post #2 of 10
Thread Starter 

bump

post #3 of 10

The last two items you listed are by fred_fred_2004. He's an established Head-fi member and regularly contributes in the DIY forum here. If you're looking to buy a CMoy, you won't go wrong with him.

 

I'm not familiar with the other two sellers. (Doesn't mean they're not good, I just don't know anything about them.)

 

The crossfeed filter adapter from Fred is based on the design by Jan Meier of Meier Audio. I haven't tried it myself, but many people like it a lot. These types of filters work best when used between the source (computer/iPod/DAC) and the amp. They will still provide a crossfeed effect when used directly with headphones, but there will also be other side effects to the sound which may or may not be desirable. 

post #4 of 10
Thread Starter 

Sweet, thanks. Nice to hear Fred is a known headfier! I'll check out his stuff at the DIY forum momentarily.
And I recognize Meiers from this thread ( http://www.head-fi.org/t/128978/headroom-crossfeed-vs-meier-audio-crossfeed ). Research made easier.


Is there a place where I can get measurements of headphone amps? Mike at Headfonia wrote a review of the JDS Labs Cmoys ( http://www.headfonia.com/60-pack-of-awesome-jdslabs-cmoy/ ) saying they were the best CMoys he's ever listened to. He also wrote a few other review on other headphone amplifiers, expressing varied opinions on each. While I do trust his judgement, I'd be curious to know about the objective differences between certain amps.

post #5 of 10

I have two amps from fred_fred (Howard) and one from JDS Labs (John). I like all of them and both engineers are class acts. While my cMoy BB2.02 has the boost switch, I seldom use it except to show my students how dramatic the sound difference is with it on. I've rolled several op amps into the BB2.02 and it's never hiccupped. My favorite from Howard is a rechargeable TI TPA op amp that is clean and pristine, and lasts forever on a good charge.

 

Every amp has its pros and cons, and each has synergy with different earphones and sources. That's one reason that I seldom use the BB: My phones are generally warm enough without boosting the bass. It's also the reason I really like the TPA amp from Howard.

 

I just won the cMoy RA-1 from ampedup77, so I'll have a pretty full portable amp contingent, soon...


Edited by Judge Buff - 5/25/12 at 5:58am
post #6 of 10
Thread Starter 

Yes, I'm sure every amp has its pros and cons. I didn't mean to say some were good for nothing at all. Some of my paranoia kicks in when I shop on eBay, that's all.

I'm relieved to hear these sellers are known and experienced, and that you're enjoying those CMoys. I'll definitely leave my paranoia on the shelf for now.

post #7 of 10

This can serve someone looking for the answers on which cmoy to consider for Grado SR80. Big thanks to Judge Buff for great and detailed explanations of his preferences, and letting me post our communication for reference here.

 

--------------

 

Just saw your post, the one saying you got your RA1-inspired cmoy from ampedup77. I am considering getting one for my Grado SR80 cans. How do you like it so far? Any experience with JDSLabs 2.03R? If so, how would you compare them. I'm torn between the two. Been getting different answers from these two guys. JDSLabs guy recommends a 9V version of his cmoy for my cans. Travis (ampedup77) says that only 18V cmoys like his can drive my cans properly.

--------------

 

The RA1 cMoy is OKAY with all my phones, but I have no Grados to pair it with. Since there is supposed to be some kind of major synergy with that opamp and Grados, I'd be tempted to lean that way. Also, I think that Travis' amp can be had for MUCH cheaper than Seaber's (though I haven't checked out prices lately). That being said, my BB2.02 from JDS has been a ton of fun for the last 3 years or so because of the ability to roll opamps. It's also powerful enough to drive my cans. Lots of upside there, Tony. Instead of having only one amp, you easily swap out the IC and you have several different sounding amps. John Seaber is a class act, as is Travis and also Howard (fred_fred2004) who does several very good amps (ClieOS is reviewing a 3 channel model of his now/soon).

 

Let me toss another amp out to ya to make your decision more difficult. My newest is the FiiO E11and I love it. It's similar to the Mini^3 in design inc opamp, has several settings for accommodating different cans and it's beau coup powerful! Mine with an extra battery and charger was ~$60 on Amazon.

 

If I had to rank them in order of my preferences currently, it would be the E11 first, BB2.03R next and then the 18V RA-1.

---------------

 

FWIW, I still went ahead and bought a cmoy from Travis (a.k.a. ampedup77), a limited version beefed up with 1000uf Nichicon caps, so there should be enough bass for the bass-heavy genres I am listening to. I will report back once I get it. If anyone has experience with Grados + cmoys, please post here. It's so hard to find info on this.

post #8 of 10
Quote:
FWIW, I still went ahead and bought a cmoy from Travis (a.k.a. ampedup77), a limited version beefed up with 1000uf Nichicon caps, so there should be enough bass for the bass-heavy genres I am listening to. I will report back once I get it. If anyone has experience with Grados + cmoys, please post here. It's so hard to find info on this.


How's that ampedup77 cMoy working for you. I was thinking about getting one to pair whit my SR225i while I save for a better one. Are there any reviews out there about Grado + cMoy synergy?
post #9 of 10

My bass boosted cmoy from fred_fred_2004 is simply perfection... You wouldn't go wrong with one of them...

post #10 of 10
Quote:
Originally Posted by tonydj82 View Post

Just saw your post, the one saying you got your RA1-inspired cmoy from ampedup77. I am considering getting one for my Grado SR80 cans. How do you like it so far? Any experience with JDSLabs 2.03R? If so, how would you compare them. I'm torn between the two. Been getting different answers from these two guys. JDSLabs guy recommends a 9V version of his cmoy for my cans. Travis (ampedup77) says that only 18V cmoys like his can drive my cans properly.

 

Contradicting replies aren't exactly helpful. Our configurations are published for anyone to see:

 

 

Quote:
What is the benefit of higher voltage?
  • Voltage supplied to an operational amplifier sets the upper and lower signal boundaries for the opamp's output. When volume is increased beyond the maximum voltage boundaries, the opamp clips the signal and you will hear distortion. Therefore, higher voltage allows the opamp to produce higher volumes when driving high impedance headphones.

    There is little benefit to increasing supply voltage for low impedance headphones (32 ohms and less). These headphones tend to demand more current rather than more voltage, so a 9V battery is adequate for most listening. Instead of extra voltage, the cMoyBB's maximum output current can be enhanced for low impedance headphones by adding a second virtual ground IC. 

    A summary of recommended cMoyBB configurations can be found under our DIY modifications page.

    All opamps are limited to "swinging" within a fixed distance from the voltage supply rails. Rail-to-rail opamps are able to drive signals much stronger before clipping. Thus, a rail-to-rail opamp is another way to achieve higher volumes, without resorting to higher voltage.

Edited by jseaber - 9/28/12 at 5:08pm
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