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Good beginner DIY amp for Grados?

post #1 of 18
3/1/11 at 6:34pm
Thread Starter 
Alright guys here's another "What should I build?" thread

I have a pair of SR-125i's (soon to be Bila'd) and am looking for a decent amp for them. I'm thinking SS at the moment just out of lack of experience with tubes of any kind (but any hybrid recommendations are welcome). I don't need any portability, so please don't think you have to limit it to portables.

The budget I'm thinking is about $75, I would gladly go cheaper (especially since it's a beginner amp), and may go slightly higher if you can really convince me that it's worth it.
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post #2 of 18
3/1/11 at 9:57pm
Have you built anything before? If not, build a CMoy. It's a great place to start and will give you the skills you need for other builds.
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post #3 of 18
3/1/11 at 10:01pm

grado sells their ra-1 amplifier for quite a bit of money, and many consider it to be a great amplifier.  If you're wondering where I'm going with that, the cmoy is a very similar design, and in many ways superior but at a fraction the cost.  A good cmoy will cost about 50 dollars and will sound very good for the price

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post #4 of 18
3/1/11 at 10:22pm
Thread Starter 
I've built some minor stuff, never anything particularly difficult, but as long as I'm not getting into surface mount stuff, I feel pretty good about my ability to do it.

The only problem I have with a CMoy is that it seems weak, which I believe was the reason the A47 was created for a pair of Grados.The RA1 is the same basic idea of a specialized CMoy right?

I guess I could try it regardless though.
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post #5 of 18
3/1/11 at 10:34pm

I'd try an Apheared 47. It's basically a beefed up version of the CMOY and it was specifically designed to drive phones like the 32ohm Grados. Check out this thread with my trials and tribulations... There are a few pics with what it should generally look like. Also, in the end, I had to isolate my 3.5mm and power jacks from my case because it is made out of tin. My pics don't illustrate this.

 

http://www.head-fi.org/forum/thread/531454/mullet-a47-thread

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post #6 of 18
3/1/11 at 10:56pm
Thread Starter 
So everybody just uses the OPA2227 and other duals, what if I want to go the OPA227 route. Would I just need to supply more voltage through this thing, since I doubled the chips, or does the dual require more power?

And I've seen single and double 9V CMoys and A47s, so does it depend on the OpAmp used or what?

I've yet to hear an RA1 so I'm a little curious how a specialized, boutique (priced anyway) CMoy can be worth the Grado retail price.
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post #7 of 18
3/1/11 at 11:16pm

Or you can PM fellow head-fier fred_fred_2004 and get a CMOY (altoids tin or desktop case) with the same high current JRC4556 chip in the RA1.   If you want to build one, he would be a good reference.  Good luck.

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post #8 of 18
3/2/11 at 3:27pm

Agreeeed with everyone else:

"JRC4556 cmoy" or A47

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post #9 of 18
3/2/11 at 3:37pm

Sijosae Class-AB with simple LM317-based power supply. :)


Edited by FallenAngel - 3/2/11 at 4:57pm
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post #10 of 18
3/2/11 at 4:29pm
Thread Starter 
I've heard of the Sijoase before, but I can't seem to find anything about it, so if you wouldn't mind pointing me in the direction of a schematic or something about it I'd appreciate it.
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post #11 of 18
3/2/11 at 4:33pm

He's a person not a particular amp, just google the name

 

cheers

FRED

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post #12 of 18
3/2/11 at 4:34pm

Funny, since the first result from a Google search for "Sijosae Class-AB" is http://www.head-fi.org/forum/thread/180624/anyone-built-sijosae-s-class-ab-amp/

 

EDIT: LOL, misspelled name tongue.gif


Edited by FallenAngel - 3/2/11 at 4:57pm
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post #13 of 18
3/2/11 at 4:37pm

Grado, not portable ? http://gilmore2.chem.northwestern.edu/projects/showfile.php?file=szeke1_prj.htm

 

What will your source be ?

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post #14 of 18
3/2/11 at 4:51pm
Thread Starter 
Quote:
Originally Posted by Fred_fred2004 View Post

He's a person not a particular amp, just google the name

 

cheers

FRED


"The Sijoase" was the lazy way of describing the amp, sort of like saying "the millet" when talking about any of the Pete Millet amps, and it's also the reason I found nothing (flipped a and s in the search).
Quote:
Originally Posted by FallenAngel View Post

Funny, since the first result from a Google search for "Sijosae Class-AB" is http://www.head-fi.org/forum/thread/180624/anyone-built-sijosae-s-class-ab-amp/


Didn't use google, and it's also no help that it was misspelled. On Bing the first result is the Sijosae DIY Gallery.
Quote:
Originally Posted by 00940 View Post

Grado, not portable ? http://gilmore2.chem.northwestern.edu/projects/showfile.php?file=szeke1_prj.htm

 

What will your source be ?


Possibilities showing up more and more as people chime in. That looks interesting. And for reference, the source will vary from the PS3, MBP, LOD'd iPod, etc.
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post #15 of 18
3/2/11 at 4:56pm

 

That Szekers buffer is nice too, I liked mine quite a bit.  Low voltage MOSFETs measure like crap, but sound sweet. :)  There are also hybrids based on 6922/12AU7/6DJ8/etc with a similar MOSFET buffer (IRF510/IRF610/etc), I've built one, sounds good but noisy as hell.

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