Will this suffice for my first build?
Mar 23, 2006 at 4:39 AM Thread Starter Post #1 of 18

thenewguy

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This is my first build and I am going to start simple with the CMoy! I was just wondering if the TL082CP Wide Dual JFET Input Op Amp8-Pin DIP from RadioShack wold be ok to use. Well to me it looks ok to use, by which I mean it fits all the specs. Also the DIP-8 pin IC sockets I am going to be using do not have gold contacts, will that be a problem? If anyone can help me it would be most appreciated.
 
Mar 23, 2006 at 4:58 AM Post #2 of 18

nikongod

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the chip will functuion if you have built a working circuit
smily_headphones1.gif


plan to upgrade it soon.

the sockets make only the most nominal difference in the "sound" of a cmoy. dont wory.

even if you stick to diy, sorry about the wallet...
 
Mar 23, 2006 at 5:44 AM Post #3 of 18

thenewguy

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Thank you so much! I was in doubt but because all the DIY guides i have looked at said that RadioShack products are crap, but for me i hate to order online and I have a RadioShack within walking distance of my house. Why should i upgade soon?
 
Mar 23, 2006 at 6:34 AM Post #6 of 18

rickcr42

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Quote:

Also the DIP-8 pin IC sockets I am going to be using do not have gold contacts, will that be a problem


not as much as not being 'machined conacts' would be though the press clips do make it easier to do opamp swaps.The TI BiFET opamp is an audio grade device but is not the highest output current opamp nor really battery freindly but no big deal since it IS a standard dual opamp package easily upgraded once the circuit is up and running.

Resistors-use the carbon films over the metal film variety pack which are "gritty"
Capacitors-the big blue film caps at 1uf are not too shabby for input coupling
Battery clips-they stock two types last i knew-go for the heavy duty ones
Connectors-the generic gold RCA's are fine,the plastic mini TRS not so very.Better to use the all metal full size TRS jack and a Mini-TRS to TRS adapter.
Universal pcb
Get the "rainbow wire" for hookup wire.a pain in the a*s to separate but a good clean sounding solid copper wire
 
Mar 23, 2006 at 7:17 AM Post #8 of 18

rickcr42

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Quote:

Why is it better to use carbon films opposed to the metal films?


all about the sound of the Radio Shack resistors.the metal film variety pack resistors have the typical "etched" sound of low cost generic metal films while the carbon films are a lot smoother and even though they are 5% instead of the 1% of the MF the packages are in sets of five so you can use an ohmeter to make Left/Right pairings
 
Mar 23, 2006 at 2:08 PM Post #10 of 18

69CamaroSS396

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newguy, FYI, I have done a dozen or so of the CMoys on the Radio Shack board. The last one I finally hit something special in comparison to all the others. First of all, I don't worry about trying to squeeze everything into a mint tin. I did that on the first one and the novelty of that wore off before I was even finished. I certainly recommend ordering from Mouser or Digi-Key or some such supplier. It's much cheaper in the end, even with shipping charges. And the quality comparison isn't even fair. You could buy 2 parts with the same Radio Shack part number and I'm not sure they would even be from the same supplier. On the amp in question, I used an OPA2132P op-amp($8.41@Digi-Key), Nichicon UPW1C102MPD 1000uF 25V capacitors(12.5mmx20mm, .76/each@Mouser), Vishay/Roederstein .47uF metal film input capacitors(.48/each), Vishay/Dale RN55D resistors(.11/each), the Alps 9mm pot from Tangent, Switchcraft jacks, and the sound quality and "pop" is amazingly different from the other Cmoys. I run it with dual 9V batteries. I've tried different op-amps, capacitors, resistors, yada yada yada, and I even built one using all Radio Shack parts, including the op-amp and sockets. That was a joke. This one stands far and away above the others. I make no claims to have enough electronics knowledge to explain why, but I do know the end result. I have over 35 years of critical listening to some pretty decent gear. It has very nice bass punch and is surprisingly less "harsh"(than my other CMoys) in the high frequencies with my 32 ohm Grado SR60s, which I feel are notorious for harshness. With my son's Beyers(also 32 ohm), the high end is almost too laid back(maybe that's from too many years of Grados), but the midrange detail and clarity is truly phenomenal for a $30 amp. The gain is set at 11, which is great for using with my Philips portable CD headphone output. I can max out the pot without it being dangerously loud. However, connected to the line level of my component Denon CD player, it plays at an extreme(dangerous) volume level. There's a bit of a tradeoff in sound quality using the phone output of the portable. It just ain't got IT when compared to the Denon. If someone had no reference like that, and had only heard this set up with the portable, I believe they would be duly impressed. You will want to tailor the gain, depending on your intended use. Having said that, it is what it is, a CMoy. Have fair expectations and you will be surprised at how good these can sound for a few bucks.
 
Mar 23, 2006 at 2:25 PM Post #11 of 18

grasshpr

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Quote:

Originally Posted by 69CamaroSS396
On the amp in question, I used an OPA2132P op-amp($8.41@Digi-Key), Nichicon UPW1C102MPD 1000uF 25V capacitors(12.5mmx20mm, .76/each@Mouser), Vishay/Roederstein .47uF metal film input capacitors(.48/each), Vishay/Dale RN55D resistors(.11/each), the Alps 9mm pot from Tangent, Switchcraft jacks, and the sound quality and "pop" is amazingly different from the other Cmoys.


Man, you use 1000uF capacitors with CMOYs? I hear a major THUMP coming
smily_headphones1.gif
 
Mar 23, 2006 at 3:43 PM Post #12 of 18

vixr

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Building with rat shack is ok for the first amp... The bug either bites you or it doesnt. The tutoial from Tangent is a Guide... Like any good guide, it leads you thru the maze and points at the cool stuff. But it is DIY! If you don't like something, figure out how to make it what YOU want... The best thing about the schematic is you can rotate the page any way you want and it will still produce a CMoy.
 
Mar 23, 2006 at 8:37 PM Post #13 of 18

69CamaroSS396

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Quote:

Originally Posted by grasshpr
Man, you use 1000uF capacitors with CMOYs? I hear a major THUMP coming
smily_headphones1.gif



The caps were extras and I decided to drop them in. I doubt that this is unprecedented. In fact, I have several CMoy2 pcbs from the following thread that use a 1000uF as the default value. In any case, this CMoy sounds great for what it is.

http://sgheadphones.net/index.php?showtopic=3220
 
Mar 24, 2006 at 3:00 PM Post #14 of 18

grasshpr

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Quote:

Originally Posted by 69CamaroSS396
The caps were extras and I decided to drop them in. I doubt that this is unprecedented. In fact, I have several CMoy2 pcbs from the following thread that use a 1000uF as the default value. In any case, this CMoy sounds great for what it is.

http://sgheadphones.net/index.php?showtopic=3220



They got nothing to do with sound quality, its just going to make a loud thump when you turn it off while still connected. I even saw one guy try a 10,000uF cap on a cmoy
smily_headphones1.gif
 
Mar 24, 2006 at 5:28 PM Post #15 of 18

69CamaroSS396

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Quote:

Originally Posted by grasshpr
They got nothing to do with sound quality, its just going to make a loud thump when you turn it off while still connected. I even saw one guy try a 10,000uF cap on a cmoy
smily_headphones1.gif



Any comments I made about SQ were in comparison to MY other CMoys, or in relation to the cost. I never said or even insinuated that the 1000uF caps made any difference in SQ, as opposed to a 330uF or 470uF, for instance. I merely listed what I had in this amp. You were the one to make a snide remark about the 1000uFs. And, in an attempt to be civil in my response, this amp makes virtually NO thump or noise of any kind when turning it on or off while connected. I always turn the amp off while connected, and I hadn't noticed any thumps or noise during numerous hours of listening, but to be sure, after your statement here, I checked again. There is no thump that could be called anything but barely audible. And I mean barely. Certainly not loud.
 

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