[DanPash]

I have had a quick look on the search, but I haven't found what I'm looking for.
I see in some peoples sig's there building the RA-1, as a project. Is there the schematic diagram floating round on here?

Any help would be really appreciated.
Thank you,
Dan.

 

[mjg]

this isn't the place to find that. yet, you can always use google ; ).

 

[DanPash]

Why thank you! I found it, its such a simple design. Just ordering the parts now.

 

[DanPash]

Is the RA-1 about the same output power as a cmoy?

 

[mofonyx]

Being resourceful lands you these links :

http://www.head-fi.org/forums/showthread.php?t=244616

http://www.head-fi.org/forums/showthread.php?t=212690

 

[DanPash]

I know its very little internally. I found a .gif file of the circuit.
My important question is, I want to build the circuit to hear it. As its Grado's reference design, and as this amp received really good reviews with cans like RS-1's, has it actually got the power to drive them to their best?

 

[TzeYang]

DanPash,

I don't really care what others say about how good it really can be subjectively.

But seriously, the RA-1 is just a lousier version of CMOY. I suppose a BB/AD based cmoy with difet inputs and better specs would sound so much better than the RA-1.

 

[DanPash]

I have built a few cmoy's, based on different op-amps and a dual channel cmoy. The sound quality was alright, but not what an M3 is capable of.

I had planned to make a TLE based power supply for each channel, and use two single channel op-amps like OPA 634's. Throw in tantalum resistors and use an ALP's RK27 pot. See how the modded RA-1 sounds as an experiment?

 

[majkel]

JRC4556 is great in making me laugh when I listen to it. I got it from a radio store for around 1$. It sounds nice but a bit funny for me. It's difficult to explain but happens. Regarding amplification - JRC4556 is able to spend ~70mA per channel so quite good as for an op-amp. However, I don't believe in miracles like RA-1 sounding terrific regardless of this part used to build it.

 

[TzeYang]

Quote:

Originally Posted by DanPash /img/forum/go_quote.gif I have built a few cmoy's, based on different op-amps and a dual channel cmoy. The sound quality was alright, but not what an M3 is capable of. I had planned to make a TLE based power supply for each channel, and use two single channel op-amps like OPA 634's. Throw in tantalum resistors and use an ALP's RK27 pot. See how the modded RA-1 sounds as an experiment?

that my good man, is an enhanced version of cmoy

The RA-1 is suppose to have huge DC pop at start up and uses an inferior power supply.

 

[Reticuli2]

 
 
Huhhhhh...
 
Not according to the measurements.  I'm a little concerned about this pop on the RA1 and the cmoy possibility of blowing out headphones with one dead battery.  Need a good near-zero ohm amp to try with the HD25, SportaPro, and t50rp.  It'd also be used with the ER4S.
 
Is the RA1 near zero ohms and can it blow out headphones like a cmoy?
 
Otherwise, I'll probably go with the Fiio E7.

 

[Reticuli2]

Also, anyone know the RA1 max input?

 

[HonoluluWalt]

This thread is super old now, so I do not know if the OP is even tuned in still.  However, just in case anyone is still tuned in and is curious regarding the "pop," I have been hearing that pop for 17 or 18 years now, and it has done no damage to my HP-1's.  Actually, I hear the pop at log distance as I turn the amp on prior to putting the headphones on.  Anyway, my HP-1 headphones still sound as beautiful as the day that I bought them (actually better, if one considers the break-in period).
 
I am not sure if this is simply a testament to the durability of the HP-1's, or if it means that the pop would be harmless to any set of headphones.  I suspect it might be a little of each.  Does anyone know for sure?
 
By the way, I love the DC-version of the amp. I could not find any other headphone amp under $500 that sounded as good to my ears.  Desclaimer:  I am over 40, and I bought this amp 17 years ago, so, with younger ears, and with newer amps, this would certainly not necessarily be the case, and there are probably plenty of sub $500 amps these days that would beat this one.  Still, I love this amp, that is my story, and I am sticking to it.  Anyone else agree?
 
It definitely delivers substantially better sound when used with the HP-1s, the SR-40s (yes, I could not resist the temptation to see what Grado could produce for 40 bucks, and I was amazed, especially when used with the RA-1), and even the Bose Quietcomfort 15s.  Originally, I bought the AC version, but switched to the DC version as it sounded a bit better (also, it makes the amp portable, but I rarely use it as a portable amp).

 

[DarkSleip]

Quote:

This thread is super old now, so I do not know if the OP is even tuned in still.  However, just in case anyone is still tuned in and is curious regarding the "pop," I have been hearing that pop for 17 or 18 years now, and it has done no damage to my HP-1's.  Actually, I hear the pop at log distance as I turn the amp on prior to putting the headphones on.  Anyway, my HP-1 headphones still sound as beautiful as the day that I bought them (actually better, if one considers the break-in period).
 
I am not sure if this is simply a testament to the durability of the HP-1's, or if it means that the pop would be harmless to any set of headphones.  I suspect it might be a little of each.  Does anyone know for sure?
 
By the way, I love the DC-version of the amp. I could not find any other headphone amp under $500 that sounded as good to my ears.  Desclaimer:  I am over 40, and I bought this amp 17 years ago, so, with younger ears, and with newer amps, this would certainly not necessarily be the case, and there are probably plenty of sub $500 amps these days that would beat this one.  Still, I love this amp, that is my story, and I am sticking to it.  Anyone else agree?
 
It definitely delivers substantially better sound when used with the HP-1s, the SR-40s (yes, I could not resist the temptation to see what Grado could produce for 40 bucks, and I was amazed, especially when used with the RA-1), and even the Bose Quietcomfort 15s.  Originally, I bought the AC version, but switched to the DC version as it sounded a bit better (also, it makes the amp portable, but I rarely use it as a portable amp).

those cans are not that "high end" so, you couldn't hear better unless you wanted to. And an Objective2 would beat it to pieces and it's nowhere near that mark around 85$ on DIY and 150$ from lord

 

[alphaphoenix]

^I think you have a few things to learn to say that the HP-1 isn't high end.