BlakeN

It is socketed. I will check the connections on that socket and the solder joints and the connection between r5 and r6. If they all look good I will rip it out. Thanks

With no load OL 4.5 OR 3.94 OG 4.5 C7 4.41 C6 8.81 across c4 8.76 At loud volume OL 4.5 OR 3.7 OG 4.5 C7 4.35 C6 8.7 across c4 8.68 I have another bit of odd information I have two sets of headphones One is 55Ohm the second is 115Ohm Both have bass distortion but only the 55Ohm crackle. The 55Ohm set has an inline volume control. If I increase the resistance to 95Ohm the headphones no longer crackle but still distortion. Remember this only happens on battery power the amp works perfectly at 13vdc Thanks for the help

I will take those measurements when I get home tonight. Here is some more info I posted in another forum (headfi.com)

I used the OPA2134 . I don't have a digital camera so I can't do pcb pics right now but it looks bad anway hehe after removing the sockets and resoldering the resistors and all other components. After doing all of that it didn't make any difference. Also the amp will play at full volume through either left or right with no distortion just not both at the same time so I cant imagine its a cold solder joint. Now I did think about a short between the channels but I used a magnifying glass to check and couldn't find any. I also measured the resistance on all of the resistors using secondary points to make sure there was good contact with the pads. The second time arround I did destroy 1 pad but luckly the trace was on the top side of the board so I soldered it there and it was fine. Once again the distortion was happening before I resoldered all the points and is exactly the same afterwards. My DMM won't measure capacitance I think at this point I might just have to buy new electrolytics so I might as well buy new resistors and sockets for my 2nd board and give it another go.

Is there any test I could do with a simple multi-meter to tell? I don't have any spare parts on hand to test with, I am using 2 nichicon 1000 uF 6.3v caps. I was thinking the same thing but I don't know how to test other then ordering 2 more caps. Here is a link to the caps I bought http://www.mouser.com/search/ProductDetail...647-UPW0J102MPD

I have been beating my head trying to figure out what is wrong with my cmoy 2. After quite a bit of trial and error this is what is happening. When both channels are active I get horrible distortion at higher volume levels. If I remove one of the opamps there is no distortion. It doesn't matter if its the left or right opamp. What I have done. Removed the POT and shorted connector. Resoldered all connections and looked for shorts. Removed the sockets I was using for the resistors and soldered the resistors in direct. (the board doesn't look pretty but it still works) Tried 3 different 9 volt batties (all were new out of box) Replaced LM6171 with a spare. Please help me

Well I completed my cmoy today. I am having a small problem though. The bass is very distorted. I am guessing I have a cold solder joint somewhere so I will be going over all the solder points again. Is there anything else that could be causing this that I should look for? I did use sockets for the resistors but I am pretty sure they are all seated well. I measured the resistance from the back side of the board and they are all right. The resistors I used (vishay rn60s I guess next time I will get 55s) were too big to fit in the space provided so I had to do some creative bending.

I am having the worst luck with parts LOL. I went to place my order tonight and of course the WIMA caps are out of stock so I got the 5% tollerance ones instead I hope that won't be a problem. I was going to get these instead but went withthe 5% WIMAs instead. http://www.vishay.com/docs/26032/mkt1817.pdf would they have worked OK?

Grrrr I thought there was another group buy going on for a second I want to get one of these but I missed out on the first two. I supose there will be another one soon.

Thanks for the tip heady. I think I am flipfloping too much though. Somone at headfi suggested the clarostat 585 (part number 585DX4Q25F103ZP) Newark has them in stock for $2.48 and it is a drop-in replacement. Might as well ask another question. The first post says you need 4 10ohm resistors but I only count 2. Am I crazy?

I think the switched alps pot is the way I am going to go. It seems the best idea. I guess I will just have to float the pot.

I will just buy the LM6171BIN from newark or somewhere else then. For some reason I thought I read that it was a replacement. Now I just need to find a POT. I know very little about building circuts so I am not going to try to do anything fancy. I need to get some books or something so I can read the data sheets and start designing my own some day I have too many hobbies as is though. Jason it is Asuka from Evangelion. I wish I had more time to watch anime. I realy want to start watching Bleach but I havent gotten arround to it. I recieved an email from newark today. They said I can call and order the alps pot but it is not available via the webpage. They are out of stock and the lead time is 105 days. Me reading the email --> What a joke.

Newark.com no longer has the Alps 290070 pot listed on their site. Can anyone take a look arround and see if there is a comparable one there? I can't seem to find one but I might be looking for the wrong thing. I was thinking of buying my supplies from mouser but they do not carry the LM617 and you have to buy 1000 of the Alps pots there lol. Is the BUF634P a direct drop in replacement for the LM6171BIN? Mouser does carry the LM617BIN. So close yet so far away It looks like others have been looking for an alps replacement on mouser. Did anyone have any luck?

Thanks. I wish the american version of farnell (newark.com) had the nice prictures that au.farnell does. I am going to have to do my searching there and then find it on newark.com.

ClieOS what knob is that? I would like to get one.

Thanks ClieOS it looks like I will be going with the Vishay Caps

hmm I might just get some black gate caps if I can't get good ones from newark. If I am going to have to pay seprate shipping for 2 silly caps I might as well make it worth it Could you explain what stat Dissipation Factor is and what a good value would be? Celios are there any other changes I need to make to the cmoy 2 to use the OP270EZ? or is it just a drop in? If anyone has any other mods to suggest let em rip I want to make the best cmoy 2 possible (within reason under $100 hehe) Edit: Ok I have been browsing arround the newark webiste some more and found a few more caps that will fit the specs. Vishay makes this one "2222 150 65471" 470uF 10x12 here is a link to the data sheet if one of the experts can take a look at it. United Chem-con makes 2 series of caps that also fit the specs the KME and the SMG if anyone wants to look at those data sheets. Thanks for all the help so far guys.

This is my current BOM if anyone wants to take a look and confirm it. Part Description - Qty - Price - Per Store - Part number - Brand 10ohm Metal Film Resistor - 4 - 0.23 - newark.com - 83F1618 - Vishay Dale 10k Ohm Metal Film Resistor - 8 - 0.42 - newark.com - 83F1561 - Vishay Dale 1.2k/3k ohm RLED - 1 Pot Alps 290070 - 1 - 4.05 - newark.com - 70C0151 - Alps OpAmp OP270EZ - 2 - 12.39 - newark.com - 05F8617 - Analog Devices LM6171BIN - 1 - 2.83 - newark.com - 41k6219 - Nat Semi 1uf WIMA Cap 63v - 5 - 0.54 - newark.com - 1049119610 - Wima 1000uF Electrolytic Cap - 2 - 0.33 - newark.com - 01E9247 - United Chem-con 1/8th Stero Jack female - 2 - 2.33 - newark.com - 35RAPC2BV4 - SwitchCraft I can't seem to fromat my post correctly sorry for the mess. I still need a switch, LED, and LED holder but I can probably get them localy. I guess I am most worried about the Electrolytic cap. Is that a good brand?

Thank you for the link! I am so new to this I didnt know about newark. I kept going to farnell.com and clicking on U.S. which was no good. I will be looking arround the site today

Thanks ClieOS. Power is not an issue this going to be 100% desk amp so I am going to use adc wall wart. What is the full part number of the op270? I tried to find it on mouser and found opa2705PA but that was the closest thing to it and of course they don't have that in stock anyway. I am trying to get everything from mouser if I can. It seems to be a bit cheaper then farnell and I live in the US so it just makes sence.

I have a completly noob question when I am looking at opamps there are letters after the model numbers can anyone explain what they mean? I am guessing it has to do with socket type OPA2227P OPA2227PA OPA2227U OPA2227U/2k5 OPA2227UA OPA2227UA/2k5 Also if I want full bass extension what is the minimum uf capcitors I should get for the electrolitic caps c6, c7. I was going to try to use black gate caps like the guy in post 226 but the recommended cap is 1000uf and he only used 330 I assume thats fine but I wanted to make sure. BTW I might listen to movies so I dont want to block any bass out. Thanks

Thanks to both of you. RancidM, a typical wall wart will work? I think I have a 12v 1000mA one arround here somewhere. Its one of these but 1000 instead of 1500 . What are the power requirements of the cmoy 2? I have sent John a pm I hope he still has some

I have been lurking for a few weeks now and I want to build my first DIY amp. I will be using it for a pair of HD595s. I thought the cmoy 2 would be a good place to start. Where is the best place to buy the pcb? I saw 1 person on ebay selling "pre-order" pcbs but I was hoping somone knew a trusted source for them. I can solder fairly well but I don't know jack about circuit design so if anyone could point me to some good instructions for building the cmoy 2 with dc jack that would be great. I can sort of read a schematic. If anyone else thinks there is a better diy amp for the same money that would better match for these cans I am all for it. I will be using this at work 100% so it doesn't even need battery power.