[klipschter]

Hey. I went to Audio Demensions, the audio department inside of the great indoors (www.thegreatindoors.com) and saw the headphones for $250. I then went to Tweeter Home Entertainment and told them the advertised price, they said they could not beat or even meet that price. I went to another Tweeter Home Entertainment, they said that they would not only meet it, but beat it by $25. So I got them for $250, then -$25, plus another -$50 from Sennheiser's website (offer is over now) so I really only paid... $250-25-50=175! So yeah, I only paid $175 for my Sennheiser HD600's with an MSRP of $450, that is $275 off the retail price, which is 62% off the retail price. What a deal eh?!

Now I am building a CMoy amp and having some issues...

1. I got the wrong capacitors
2. I forgot the potentiometer
3. It say it is a one channel amp... but i want stereo... am I just messed up the head?
4. I have no clue if I got the right OPAMP, I got the TL082 Dual Bifet OPAMP from Radio Shack (Part# 276-1715)

5. Some other minor things.

I know that this is not the best amp, but i really don't even need one, and I just wanted something to do, hence why I did not care to get super quality parts, just the best Radio Shack sells.

This is the amp I am building, as if you did not know haha.
http://headwize.com/projects/cmoy2_prj.htm



271-309A::50 Piece Metal Film Resistor Assortment

274-246A:

2) For stereo input and stereo output

276-1715:

2) TL082 Dual BIFET OPAMP

272-802::::20 Assorted Electrolytic Capacitors

276-149A::General Purpose Component PC Board

278-1223::18AWG electrical wire

276-2400::5x5 inch Antistatic Conductive Foam

275-624A::MicroMini Toggle Switch

276-309::::5mm Wide Angle Red LED (1.7V-20mA-800mcd)

276-079:::

5) Snap-in Panel Mount LED Holders

64-009A::::Rosin-Core Solder

A 9V Battery

A 9V Battery connector

Altoid (Cinnamon Flavor) Tin



Total was more than expected, $33.31. I will return the capacitor pack I bought since out of 20, it has NONE that I need haha. I am going to use the potentiometer design instead of the switch as you can see.

So, what did I mess up?

I know I should have gotten the 276-310 LED, but they were out, this was the lowest powered one they had, and is clear which is nice, and i don't care if it is not super bright. Longer battery

Any help would be great.

Also, i wanted to have the audio simulator built into the same altoid can...
http://headwize.com/projects/showpro...=cmoy1_prj.htm

think it woudl fit? i would just have two mini plugs still, input to the similator, then out to the amp just using cables then out from teh amp via another mini plug. waddaya think?


Also, what is the best solid state amp for these headphones for less than $100 that I can build from the headwize site, or otherwise? I see so many there but really don't know which to build. Thanks!!!!!


-justin

http://www.soundwise.org/

 

[TaffyGuy]

http://tangentsoft.net/audio/cmoy-tutorial/index.html

after this, read cmoy's article again _carefully_ and i suggest you do some searches on these 2 forums.

you have a lot of research to do. i know, i was very anxious when i started (just a month or so ago) ...and i still am. gotta do the homework first.

 

[klipschter]

i hav read all of that stuff. my problem came from schematics of a mono amp and pictures of a stereo amp... so i need two of everything i see in the schematics basically.

screw the cross feed, i don't really need it anywho. just want to build the altoid can amp and later on a non portable amp.

 

[TaffyGuy]

click on the link in my sig if you want inspiration

 

[tangent]

I'm biased here, but Taffy's right: read my tutorial. I was once a raw newbie like you, and I also started out building all-Radio-Shack amps. I've learned a thing or two since then, and a lot of what I've learned has been set down in that tutorial. If you take the time to go through it, you'll be cured of your newbieness much quicker.

Enjoy your eventual amp!

 

[JMT]

I am not biased here, but Tangent's right: Read his tutorial. Most of what I learned I learned through trial and error....and many posts over on HeadWize. Apheared, ppl, Daniel Pumphrey all were great helps. But Tangent's tutorial eliminates most of the error part (you actually do learn when you screw up though). It is almost a must read for DIY newbies.

Good luck, don't forget to have fun!!

 

[klipschter]

LoL I have read the tutorial. I was just wondering if you could see a problem with anything so far, product wise.

Also to see your recommendation on a DIY home amp, IOW, non portable.

I have been trying to get in touch with apheared but the email i used to use with him no longer works, the hotmail.com one. anyone know his new one? you can email it to me prevent spamage

justin@soundwise.org

 

[tangent]

Perhaps I should have said "follow the tutorial", then. If you had, you wouldn't have made those mistakes.

As for recommendations for a home amp design, there are two kinds. One is an amp that must be plugged into the wall just because it draws so much power. This includes the Gilmore, the Szekeres, and virtually all tube amps. Then there are the amps that can be portable, but all of those can also be made into a home amp as well, usually by removing parts restrictions. For example, op-amps that you might have rejected for a portable amp due to high quiescent current draw can be used in a home amp. My point is, there are a great many amp designs to choose from if you want a home amp. But probably you should continue building your Cmoy amp for the practice, and then pick a second amp later on. That's why I say in the tutorial that you probably won't save money DIYing -- you end up making more than one amp, so if you only wanted one amp, it's often cheaper just to get a commercial one or have someone else DIY an amp for you to begin with.

And on the status of Apheared, of his own choice he's incommunicado. That's all most of us know.

 

[nobody020]

I also built a cmoy recently, following tangent's tutorial, and i've gotten everything wired, except when i plug into any of my sources(sony d-e500) and computer sound card, i get a bit of hissing noise. if I mute the soundcard, then there's no noise at all. if my cd player is paused, then the noise becomes more apparent, but it could be caused by the cd's motor, since i can hear it between tracks when the cd plays. anyone have any ideas? is this oscillation? or is that eliminated because I don't have any noise without a source? or do i need to upgrade my stuff?

i've been testing with a few pairs of cheap earbuds, and my ksc-35s... no luck so far. i have r5 at 47ohms, per tangent's tutorial.

someone please help! the sound is really good, except for the staticky part.

thanks

-nobody020

 

[tangent]

Your sources suck, nobody020, and the CMoy amp is revealing enough to show you this. Whether this is a good thing or not I'll leave to you to decide.

If it were oscillation, it would either happen as soon as you turn the amp on, or it would distort loudly on some sections of the music. (The latter isn't necessarily oscillation -- it's just one possibility.) If you turn off the source or unplug it from the amp and the noise goes away, the source is noisy. Pretty straightforward.

 

[nobody020]

hey thanks tangent,

yup. my sources do suck. I can't help that my family believes in the value of "hand-me-downs" through generations of electronics. I tried the amp with a really old Panasonic S118Z portable that has a line out, and it worked fine without any noise. It sounds great! Thanks for writing that tutorial!

Now all I have to figure out is why my volume control isn't working. When I have it to the very counter clockwise position, I hear absolutely nothing, but if I bring it up just a bit, the sound becomes really loud. Also, when I touch the volume control or shift it, it sometimes results in distortion.

thanks again,
-nobody

 

[tangent]

Hand-me-downs are a good thing -- they got you started, didn't they? If you're going to upgrade, you can hand them down to someone else in your family who has nothing. A sucky player is better than no player at all.

As for your volume control, you've just got the wires hooked up in an incorrect order. You can probably figure out the right order faster than I can puzzle out what order you've got the wires in now.

 

[nobody020]

Okay, now I've got a problem.

I swapped out my original 10K ohm volume pot for a 50K one, and now the 50K one gives me a lot of noise when i have it turned all the way to the left, but none when I turn it to the right.
any ideas? My 10K pot was working fine, and the 50k one is wired the same way as the 10k one was.

thanks

-nobody020

 

[Dev]

Do you increase next parallel resistor (after pot) to necessary value (x10 of pot)?

 

[nobody020]

whoops. i needed to do that? haha.. thanks for the tip. so I would need a 470k ohm resistor instead of that 100K thing i'm using now huh? What exactly is that resistor for?

thanks!


-nobody020