Yeah, I made my first CMOY
May 18, 2002 at 1:52 AM Thread Starter Post #1 of 26

mkyy

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oh yea, made my first CMOY.
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too excited! Just wanna share the joy!!!!
Thanx tangent for you excellent tutorial.
man, this is addictive, I'm already planning my next project.

What your suggestion for my next project?

Cheers
 
May 18, 2002 at 3:11 PM Post #6 of 26

tangent

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Quote:

Thanx tangent for you excellent tutorial.


Glad to be of help!

Quote:

What your suggestion for my next project?


You could go through all the tweaks in the tutorial. That would get you a high-end CMoy. Then you can go for an uber-Cmoy by adding buffers, faster capacitors, etc. Or, try going for a micro-cmoy -- pack the thing down as tight as you can to allow for more batteries or a smaller case.

You could start rolling some different op-amps into your CMoy to tune its sound.

Or, if you're bored with op-amps now, you could try one of the several discrete and tube amps in Headwize's library. Or, one of the other op-amp designs, like the Apheared #47 or #42. A lot of people like to take a CMoy type op-amp circuit and use it as a voltage gain stage for the discrete Szekeres current-gain amplifier.
 
May 19, 2002 at 3:57 AM Post #9 of 26

mkyy

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Hi Tangent,

Thanks for your comment. I'm actually thinking of building a high-end CHA47 to get a little more practice, then something fancy. Have you build the Morgan Jones before?? Do you have any comment on it?? in terms of difficulty??
 
May 19, 2002 at 6:20 AM Post #10 of 26

millerdog

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Just wondering, but is the Hansen board available for this project? I printed up tangents parts list then went back to cmoys article and when I hit the hansen link it sent me to email...
Will the board help me with construction? Or should I just stick to the breadboard?
By the way tangent...I spent like forty bucks at digikey! So much for the twenty dollar amp! Instead of those plastic cases, I was seriously thinking of how I could do this in a poptart box! lol
on the way!
md
 
May 19, 2002 at 7:05 AM Post #11 of 26

tangent

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Quote:

I'm actually thinking of building a high-end CHA47 to get a little more practice, then something fancy


Sorry to be pedantic, but a lot of people misuse the term "CHA47" -- that only refers to an Apheared 47 on a Hansen board. I ask because "high end CHA47" isn't very high end at all -- about all you can easily do is use better op-amps and add an out-board power supply circuit. To some extent, you can also use better capacitors, but the Hansen board limits how big those capacitors can be.

When I think of a high-end Apheared 47, I think of protoboard. Then you can get really wild.
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Quote:

Have you build the Morgan Jones before?


Sorry, no.

Quote:

I hit the hansen link it sent me to email... Will the board help me with construction?


Absolutely. You just solder the parts in and you're done. Even when you have a pre-planned layout like my tutorial gives you, it's still slower to build on protoboard. And, I'm not aware of any sample layouts for a Hansen (or an A47 for that matter) on protoboard, so it will be even slower to build these on protoboard than on PCB.

The main disadvantage of PCB is that it's inflexible. Sometimes a PCB can have flexibility designed into it, like my META42 board, but even then, it only has as many points of flexibility as the designer thought up in advance. With protoboard, you have as much flexibility as your protoboard budget allows.
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Quote:

I spent like forty bucks at digikey! So much for the twenty dollar amp!


Heh. I admit, $20 is definitely low-balling it -- absolute bare-bones. To hit that target, you need to:

1) Use OPA2134s instead of 2132s. This is false economy in my opinion, because a 2134 won't sound as good at lower voltages as a 2132 will, so you end up spending more money in batteries.

2) Use Radio Shack switches. If you avoid the micro-mini ones, you can get NKK-like quality without the NKK price.

3) Use a mint tin or similar for the case. This is probably the biggest single cost savings.

4) Use only a pair of 1/8" jacks. No RCAs, no 1/4" jacks.

5) Go with metalized polypropylene caps. They're smaller and cheaper, and fairly close to film and foil polypropylene in performance.

6) Don't socket the chips

7) Use cheaper knobs. Those Kilos I recommend are fairly spendy. ($5+ apiece.)

You probably had to buy extras of some things, too, so that jacked the cost up some, I'm sure.
 
May 19, 2002 at 7:24 AM Post #12 of 26

millerdog

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Tangent, I hope you didn't take offense at my post! I just wanted to point out that if you decide to make the right choices in parts..it won't just cost you twenty bucks...I apologize that I didn't make that apparent.
Tangent, if not for your tutorial, I would not even be asking these questions. I should have stated that I used most of your alternative components; my desire was to build a good amp the first time. My post did mean to imply that your information was incorrect! Hence the lol.
I studied your tutorial well before deciding on what parts I was going to order. On the most part, I chose the parts I(my opinion) thought you were most happy with.
Your website rocks! I went down the parts list with digikey and had no real problems.
thanks for publishing this in a public forum!
md
(edit) I ain't being a kiss ass...Though I am sure I'll still need help with this!
 
May 19, 2002 at 7:27 AM Post #13 of 26

mkyy

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Quote:

Originally posted by tangent
When I think of a high-end Apheared 47, I think of protoboard. Then you can get really wild.
smily_headphones1.gif



That's what I'm planning indeed.
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I might not be the best person to give comments, just some tips for those who're planning to first time DIYer.

1) Patience, patience and patience.

2) If you've really hot opamp, you've reversed the V+ and V- ( you wonder how i know this.. )

3) Pay attention to the orientation to the opamp.

4) As JMT suggest before, buy more parts than needed. You might end up breaking some parts. Even if you don't, you need it for some other project cos this's highly addictive
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5) Use the "search" function a lot on both head-fi and headwize, when you need to troubleshoot your amp. Post it on the board if you can't find it in the archives.

But tanget's tutorial is very well illustrated, should've no problem completing it.
 
May 19, 2002 at 9:23 AM Post #14 of 26

tangent

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Quote:

I hope you didn't take offense at my post!


...And likewise I hope you didn't get bugged by my post. I realized you were just yanking my chain, but I also saw that you had a valid point: I threw out that $20 number without justifying it, and that's misleading. I've updated the site with info showing how to get the cost down to $20, if one so cared. It's more detailed than my last post, so you might find it interesting reading.

Quote:

If you've really hot opamp, you've reversed the V+ and V-


You're lucky the thing survived! (Or did it?) Another thing that will make an op-amp chip get hot is oscillation. This is one quick and easy way to tell without an oscilloscope or an ammeter. If you can hold your finger on it for 5 seconds and not want to remove it, it's cool enough. Otherwise, better check the circuit for faults.
 
May 19, 2002 at 10:30 AM Post #15 of 26

Jeff Guidry

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My dual 9v CMOY with Meier crossfeed (built by JMT
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) has the OPA2134s. If I were to upgrade these, which opamp should I get? How difficult is it to roll the chip?
 

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