A while back I got the headphone bug and purchased a pair of Grado SR80 headphones [new model: SR80i]. I am very pleased with the inexpensive ($99US) headphones which deliver great value. The Grado SR80 headphones have an impedance of 32 ohms, so I built a CMoy Headphone Amplifier in an Altoids mint tin to drive the somewhat demanding headphones. The results were surprisingly good, especially when you consider that one can easily build a CMoy Head Amp for about $20. The CMoy was a huge improvement to a portable media player and rivals the performance of the built-in headphone amplifiers on my NAD C162 and NAD 1020 preamplifiers.
A while back, I was showing off the Grado SR80 headphone / CMoy combination to a good friend. He is the Walkman, Discman and now iPod type who typically lives with the factory supplied headphones until they die, replacing them with similar light travel headphones. He was stunned with the amazing sound quality, so I let him live with the Grado / CMoy combo for a while. Not surprising, he loved the sound quality, but found that the Grado headphones were too bulky and leaked too much sound for use on public transit.
While he found that the combo was not suitable for his daily commute, he was in love with the amazing sound quality and decided to spoil himself. He purchased a pair of Grado SR225 headphones and a Grado RA1 headphone amplifier for use at home.
For those of you who are not familiar with the Grado RA1 headphone amplifier, it is well regarded, runs off of two 9V batteries, is housed in a beautiful mahogany enclosure and retails for about $350US. A stock photograph the Grado RA1 is shown below.
Recently I had the opportunity to visit and listen to his Grado SR225 / RA1 combination. Of course I brought along my little pocket CMoy headphone amplifier! :)
We both did some blind listening and in the end we pretty much had the same listening impressions. We thought that both the CMoy and RA1 amps sounded excellent and fairly similar, but we both gave a slight edge to the DIY CMoy amplifier. We were both a little surprised, considering you can build a CMoy for about $20 or buy an already built one for about $40 on eBay, yet the Grado RA1 rings in at $350.
A while back, I was showing off the Grado SR80 headphone / CMoy combination to a good friend. He is the Walkman, Discman and now iPod type who typically lives with the factory supplied headphones until they die, replacing them with similar light travel headphones. He was stunned with the amazing sound quality, so I let him live with the Grado / CMoy combo for a while. Not surprising, he loved the sound quality, but found that the Grado headphones were too bulky and leaked too much sound for use on public transit.
While he found that the combo was not suitable for his daily commute, he was in love with the amazing sound quality and decided to spoil himself. He purchased a pair of Grado SR225 headphones and a Grado RA1 headphone amplifier for use at home.
For those of you who are not familiar with the Grado RA1 headphone amplifier, it is well regarded, runs off of two 9V batteries, is housed in a beautiful mahogany enclosure and retails for about $350US. A stock photograph the Grado RA1 is shown below.
Recently I had the opportunity to visit and listen to his Grado SR225 / RA1 combination. Of course I brought along my little pocket CMoy headphone amplifier! :)
We both did some blind listening and in the end we pretty much had the same listening impressions. We thought that both the CMoy and RA1 amps sounded excellent and fairly similar, but we both gave a slight edge to the DIY CMoy amplifier. We were both a little surprised, considering you can build a CMoy for about $20 or buy an already built one for about $40 on eBay, yet the Grado RA1 rings in at $350.
After a few Google searches, we found that others had reported similar listening impressions between the two amps. That being, they both sound very good, with similarities between the two and the slight edge going to the CMoy. But what I found most interesting were these two sites, one which showed the dissection of a Grado RA1 headphone amplifier and the other which also took apart and upgraded the Grado RA-1. The sites provide pictures of the inner details of the RA1 and also a schematic for the amplifier section. The schematics below show the both the Grado RA-1 and CMoy headphone amplifiers.
Schematic - Grado RA1 Headphone Amplifier
Schematic - CMoy Headphone Amplifier
Both the Grado RA1 and CMoy designs use a basic non-inverting amplifier circuit using an operational amplifier (opamp). For my CMoy, the opamp used was a OPA2132PA (Burr-Brown) which retails for about $5 and for the Grado RA1 uses a JR4556 that retails for about $0.50. Despite the fact that the JR4556 is a low cost opamp, the RA1 sounds decent, but not as good as a properly implemented CMoy headphone amplifier - (DIY lets you choose the gain setting).
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