[Haoleb]

Hey. well a friend sent me 40 bucks and im going to build him a headphone amplifier. I was originally going to bui9ld one for myself but this came up. I am stuck on weither to build a Grado RA-1 clone or the Cmoy. i need to be able to get all the parts for under 40 bucks and id like to make it nice. There is a nice aluminum heatsink box at parts express i like but its 15 bucks. but worth it IMO. But what i want to know is, which one will be eaiser to build and sound better. It will be used with Grado SR-60's. And do you think it would even make a significant diffrenece with those phones? Thank you for your help.

 

[was ist los?]

Hey, i've built several of both. On mine, i usually use premium parts. You could build a pretty decent cmoy for around $20-30 exclusive of the case. However, an RA-1 will cost around $35-40 also exclusive of the case. I too have the SR-60s and they don't really react to amps much, but i can still tell the difference between the cmoy and RA-1. I like the RA-1 clone more: more soundstage and smoother overall sound. Also, more detail over the cmoy. Are you planning for a home amp or portable?

 

[Haoleb]

well, its not for me, its for my friend. and i think he would probbly use it as home and portable. but if you dont think it makes much of a difference with the SR-60's maybe i wont build it. I have the SR-125's so if i built it, i would be intested to see the results but im not going to spend 40 bucks on something that wont really make a diff for him. for me to get all the parts would be around 30 bucks for the RA-1 and the case i like is another 15 so i dont think i have enough for it anyway

 

[Haoleb]

OK ok. Change or plans. instead of buying a box im going to build one out of wood. And its gonna be beautifull when its done too. But now i want to add an LED to the RA-1 but i need help with how to wire it. The schematics that i have dont have any info on the led. If someone could tell me what i would need to do that it would be very helpfull!

 

[Squalish]

LEDs are pretty simple - in series with a current-limiting resistor(in front or back), hooked up to wherever the on/off switch connects to the amp. Make sure it's in the right position(IE + and - ends go to correct PS polarities), and you're good to go.

Figuring out the resistor for the LED takes a little math. The LED should have a voltage drop rating and a maximum current rating(in milliamps).

Vsupply - Vdrop = amps * ohms
18V - 2V = 0.002amps*8000ohms
18V - 2V = 2ma*8kohms

Shoot for a high enough resistor that you don't exceed the current of the LED and you're fine. LEDs need around 0.1ma-1ma to light up detectably.