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Cmoy components/gain - Page 2

post #16 of 50
Quote:
Originally Posted by joeyjojo View Post

FYI tangent the first link on that page is dead (redirects to FS subforum).

 

That happened when Head-Fi switched to this new forum software.

 

I've just removed the link and replaced it with the basics on DIYing it.

post #17 of 50
Thread Starter 
Double post, my phone is lagging...
Edited by UnknownAX - 4/14/13 at 3:01pm
post #18 of 50
Thread Starter 
My parts are on the way and I ordered two njm4556's just because they were so cheap. Could I plug them into the cmoy/a47 without any further modifications?
post #19 of 50

On the subject of supplying power to a Cmoy, would there performance issues when using a 12v plug pack? I'm considering building a desktop Cmoy wanting to avoid batteries using one using one (12v pack) and am not sure if this would affect the sound quality.

post #20 of 50

Theres no issues just make sure any capacitors you use have a high enough voltage rating

 

cheers

post #21 of 50

Also make sure the plug-pack has a floating output if you want to use a virtual ground. 

post #22 of 50
Thread Starter 
I'd like to switch between inputs, is it okay to use a cheap 2-channel switch for that? Or would a switch in the signal patch mess up the sound?
post #23 of 50
Quote:
Originally Posted by UnknownAX View Post

I'd like to switch between inputs, is it okay to use a cheap 2-channel switch for that? Or would a switch in the signal patch mess up the sound?

 

Totally fine. Either get a double pole double throw switch and switch both signal and grounds, or get a single pole double throw switch and only switch the signal line and tie the grounds together at the inputs (I'd probably do the latter).

 

Of course you can have more inputs than two using a single pole N throw switch for N inputs.

post #24 of 50
Thread Starter 
Really? Everyone's so serious about cables, connectors and everything in the signal path and then you tell me that I can put any switch (no matter what the contacts are made of, etc...) in the signal path???
Or are things put between source and amp less critical than things between amp and headphones?
post #25 of 50
Quote:
Originally Posted by UnknownAX View Post

My parts are on the way and I ordered two njm4556's just because they were so cheap. Could I plug them into the cmoy/a47 without any further modifications?

 

Did you balance the input offset currents? 

You may get output voltage offset if you did not. 

Measure before you plug in your headphones. 

 

Quote:
Originally Posted by UnknownAX View Post

Really? Everyone's so serious about cables, connectors and everything in the signal path and then you tell me that I can put any switch (no matter what the contacts are made of, etc...) in the signal path???
Or are things put between source and amp less critical than things between amp and headphones?

 

The people you included in "Everyone" are seriously mistaken. 

 

If you are seriously worried about cable or switch sonics, I would start your journey to better sound by building anything but a cmoy. A Dynalo or Pimeta would be on my list. 

post #26 of 50

You're misusing that word, "everyone." The Cult of Cables doesn't enjoy universal belief.

 

If you want to spend more money, get a 3-pole switch, so you can switch the grounds out, too. That will avoid the need for the CMoy's weak virtual ground to cope with both source's behaviors at the same time.

 

That's not to say that all switches are created equal. The cheaper sort will break, and the contacts will become dodgy more quickly. But no, you don't need to find a switch hand hammered out of six-nines gold by the nude virgins from the Unicorn Colony.


Edited by tangent - 5/3/13 at 8:29am
post #27 of 50
Quote:
Originally Posted by tangent View Post
But no, you don't need to find a switch hand hammered out of six-nines gold by the nude virgins from the Unicorn Colony.


What am I going to do with all those nude virgins now...

post #28 of 50
Thread Starter 
I knew I would start a war by using the word "everyone", but it is somewhat the impression you get on head-fi. "Use this cable and you get +6db at 60hz and -0.0001db at 6000hz, blah,blah.....) smily_headphones1.gif
I don't believe in it either, but cheap switches with flimsy contacts and grease everywhere make me think a little bit.
I'll buy a switch like this and it'll be fine,right? 5212%20220.jpg

Btw. I'm not really switching between inputs, I'm switching a bandaxall tone control circuit on/off at the amp input.
Edited by UnknownAX - 5/3/13 at 9:53am
post #29 of 50
Thread Starter 
The parts arrived today and I assembled the amp like shown here: http://williamneo.blogspot.fi/2008/03/grado-ra1-headphone-amplifier.html?m=1
The only modification I did was using a sijosae discrete rail splitter instead of the resistor divider. I left the decoupling caps on the power-pins, though.
I get audio on both channels, but it makes a loud "click,click,click" noise and eventually, the opamp will get hot. I've checked everything, but I can't find any problem...
Btw. With grounded inputs the clicking sound stops.
Edited by UnknownAX - 5/6/13 at 3:37pm
post #30 of 50
Thread Starter 
I had the right channel connected to the ground at the input...lol! It works like a charm now. The gain is way too high, though. Does anyone know if the njm4556 is unity gain -stable?
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