FS: Custom 'CMOY' headphone amps

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groggory

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I'm building these myself and am placing an order to a few of the major component houses within the next few days. I'll build a CMOY amp to your specs. Or if you don't know what you want, I'll build you a base configuration as defined by Tangent on his site(which sounds quite good too).

A few mods from the base configuration I might suggest include:

  • Larger C1 (DC blocking caps)
  • Remove DC blocking caps (improves performance, but if you have a bad source you can destroy your headphones)
  • Different Opamp
  • Change Gain (If you use Grado headphones a gain of 4 is recommended)
  • Remove volume knob. Reccomended if you are using for portable applications and your mp3/cd player already has a volume control or if you would rather just use window's built in control in a computer environment
  • Different Input/ Output connectors (ex. RCA inputs, 1/4" headphone jack
  • Use of TI2426 "Rail Splitter" IC in place of the divider network (improves amp performance, and battery life)
  • Differnt on/off switch (mini toggle is default)
  • Include an AC jack
  • Different case (I enjoy working with the mint tins (altoids), but will just as easily work with the various pac-tec, hammond, and other cases.
  • Anything else you want
Notes
Default Gain will be 11, unless you otherwise ask.
Default Opamp will be OPA2132PA dual opamp
Default resistors are digikey generic 1% metal film
Default LED is red low current, unless otherwise mentioned
Default source is 1x 9V unless otherwise mentioned
Amp is constructed on Radioshack stripboard

Links

Tangent's Cmoy page
Original Cmoy artical by Chu Moy
My Headphone Amp Website
[H]ard|Forum Electronics Forum

Price

I'm doing a simple price structure here. It is just

Component costs (without shipping, with tax) + $15

A typical amp should cost in the mid $30 dollar range. Payable by paypal, check, or money order.

-----------------------------------

Feel free to email me [email protected] or catch me on AIM )groggory). I'll answer any of your questions that you may have.

Last date for you to place orders for this shipment:

Saturday, March 6, 2004 at 12:01pm PST
 
Ok...

So, for someone that uses Grado SR-60's, and a pair of Sennheiser HD280-Pros, what kind of settings would you recommend? I use the Senns for Home theater (laptop headphone out), and traveling music/gaming. The Grados are hooked up to a computer for music or to my Aiwa cd player.

What would you do? 1 amp, or 2? What settings? :)
 
How do these amps sound with the Shure E3s? Ive heard the Shure's can be a but finicky with amps.
 
How do these amps sound with the Shure E3s? Ive heard the Shure's can be a but finicky with amps.
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As far as I can tell, there should be no problem amplifying the shures. However, I have never used those headphones before so if there is an issue, point me to a detailed accounting of it and I give you a better answer.

They might just be very revealing headphones. If the amp puts out a slight hiss you will hear it. That sort of thing. So most likely the amp for them will just have to sound very clean, hiss and crackle free, and be very neutral.

The cmoy is a great amp, but if those headphones are indeed that revealing, moving to a more advanced and cleaner topology such as a PIMENTA, MINT, PPA, or similar amp might be worth looking into.

These are excellent amps, but they cost a considerable amount. The reason I am pushing the CMOY is that I can build it for not very much, while using high quality components, and having it sound very nice. If you are unwilling to spend the money on something like the PIMENTA, you may want to look into a very advanced CMOY. With some extra bells and whistles to make it sound extra clean.

For example a better opamp, better or no input caps, better powr supply caps, lower noise resistors. Its basically just a maxed out cmoy.

But I really recommend saving for a PIMENTA or similar if you're looking to do that.
 
I'm kinda interested in these, and I've got a couple questions for ya, if you don't mind.

The amp sounds good, but I know these things are pretty finicky. How much experience do you have in this area? I mean, how many amps have you built? Could you post some pics of your work? thanks! I'll be in touch!

-Zemo
 
Originally posted by Zemo
I'm kinda interested in these, and I've got a couple questions for ya, if you don't mind.

The amp sounds good, but I know these things are pretty finicky. How much experience do you have in this area? I mean, how many amps have you built? Could you post some pics of your work? thanks! I'll be in touch!

-Zemo
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Actually, the cmoy is anothing bug finicky. As long as you pick a nice opamp to work with.

But as for my experience, I'm a third year CompE student. I have built 3 amps so far (1 cmoy and 2 integrated headphone amps) and am currently building a MINT and Grado RA-1 clone for my personal use.

Through all my work I have not had a single hickup. Well, except for the person that I built the CMOY for wanted a DC power jack at the last second, and I didn't have an insulated one. But that's not a problem as much as an annoyance.

I have a couple pictures of my work, but I'll try and get some more pics. I have to contact the guy I sold the cmoy to and snap some pics. I do good work and am very a perfectionist when it comes to this stuff. If you don't want to take my word for it you have every right, and you can have an amp next batch I make. Otherwise, as I stated in my first post, my order date is coming up soon.

I'm working on some common configurations and prices. I'll post them when I finish.

Thanks alot for the interest!
 
That sounds pretty good. I'm in the market for a higher end home based amp as well, and you sound like the right guy to build me one. I was lookin' around and found this amp. Something called a pimeta? My budget is in the $200-$300 range. What can you do?
Pretty.JPG
Front.JPG
 
Originally posted by Zemo
That sounds pretty good. I'm in the market for a higher end home based amp as well, and you sound like the right guy to build me one. I was lookin' around and found this amp. Something called a pimeta? My budget is in the $200-$300 range. What can you do?
Pretty.JPG
Front.JPG
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The picture you linked is a pimenta housed in a hammond mfg case, using a neutrik locking jack, and the variety of aluminum knob that is carried at digikey (I can't remember the brand).

I'm actually ordering the parts to build a pimenta for a friend right now. Your budget is plenty and we should be able to build you a very nice amp with premium audiophile parts throughout with that budget. Check out my topologies homepage for more info on the pimenta and other topologies. I update it frequently and put all the best stuff I find on there. The pimenta is a wonderful amp that will defintely satisfy the high end audiophile in you.

Let me know what kind of configuration you'd like and I'll send you a quote. Also please let me know what kind of headphones you use so I can optimize it to your usage.

Example

Inputs:
2 stereo RCA switched
Output:
1 1/4" locking jack
Case:
Hammond Aluminum case
Power:
A/C
LED color:
Blue

Also, do you see yourself removing the RCA cables very frequently, or are you planning on leaving this hooked up constantly? I ask because there are different RCA plugs optimized for frequent pluging and unplugging and others that aren't. You'll have a very nice connection either way, its just a question of good design

Another question is, do you enjoy crossfeed? The pimenta has a very nicely integrated crossfeed circuit. If you are not familiar with what crossfeed is, basically it lets a little of the right channel into the left ear, and a little of the left channel into the right ear. Headphones are very closed as to what channel gets to what ear, but the human brain is used to more open air, speaker style sounds that allows everything to be heard by both your ears. If you think you might like this find some binaural recordings and take a listen. If you would like to try it, we can build it into your amp but put a bypass switch, so you can turn it off and on as you see fit.

I hope I've helped you a bit, and am looking forward to seeing your pimenta on my workbench very soon :D

Post your specs on here or email them to me and I'll quote you ASAP
[email protected]
 
WTF is a Pimenta?
It kills me that you don't even know the correct name of a product that you offering.

Furthermore this is a place to sell finished goods ... not a place to advertise your services.
The last time I posted a thread like this (witch BTW advertised the same type of a service) it was deleted and I was told the very same thing I just passed along to you.

And Zemo FYI that amp sold for $155
The total package wich included the Amp, Wall Wart, Cables, Shipping and Paypal fees was $225
The second set of Burr Brown opamps were freebies. ;)
 
Originally posted by X86Dude
WTF is a Pimenta?
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I posted a link to my topologies page in the post before yours that included a link to the pimenta. The PIMENTA is...

"It's a PPA-Inspired META42 successor. It's about the same size as the META42 board, but the topology is closer to that of the PPA." - Tangent

The info can be found on tangent's site here
It kills me that you don't even know the correct name of a product that you offering.
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That is the correct name so please don't accuse someone of something unless you are quite sure. Its just not polite.
Furthermore this is a place to sell finished goods ... not a place to advertise your services.
The last time I posted a thread like this (witch BTW advertised the same type of a service) it was deleted and I was told the very same thing I just passed along to you.
Click to expand...
I could very easily sell these prebuilt, but I thought allowing people to spec them would be much nicer to them. Everyone has different applications.
And Zemo FYI that amp sold for $155
The total package wich included the Amp, Wall Wart, Cables, Shipping and Paypal fees was $225
The second set of Burr Brown opamps were freebies. ;)
Click to expand...
I know that you also build amps so you should know as well as I do, that the price will change wildly with what components you use. If you would like here is the line by line price sheet for the pimenta I'm specing out for him. Its a very nice pimenta, with just basic single input, single output, with no crossfeed and no wall power, and it is costing $160 in parts (no tax no shipping). I'm not finished with those specs yet, but they give you an idea on how varied the costs can be. Add in a couple more nice vampire RCA's at ~$20 apiece, a nice linear power supply for ~$30 and you're at $200 in parts. Plus labor plus shipping I'm easily at your price. If I were to use panasonic caps instead of the elnas, dayton RCA's instead of the vampires, radio shack wall wort instead of the nicer ones, generic film resistors instead of the vishay dales then the price would come down considerably.

I'm just building people amps to their specs. The price falls where it may, and I am not making a killing off these. All I'm asking is a very reasonable builder's fee, cause it does take a good amount of time to put these together and finish them into a nice, quality amp. In my first post I posted my pricing structure. Its linear, not exponential or logarithmic. I charge you (parts + labor + ship ). Its pretty simple, and I think very fair. Hopefully you'll agree.

But anyways, just wanted to clear up those 'questions' so everyone knows whats happening. :) If I made any errors back there, just point them out to me and I will either correct them, or bring attention to side of the story.

THANKS!
 
I made a few of these using the opa2134 chips from TI. Nice little thing. I use it for amplifying the weak sound output from my mini-disc player and also as a guitar preamp. Works good in both situations.
 
Originally posted by rm.o
I made a few of these using the opa2134 chips from TI. Nice little thing. I use it for amplifying the weak sound output from my mini-disc player and also as a guitar preamp. Works good in both situations.
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Yep. I'm using the OPA2132 in the ones I've been building. Same family of chips so the sound is about the same They sound nice, and are very forgiving to circuit changes.

Thanks for the <thumbsup>
 
Hey, thanks for your post groggory.
That is the correct name so please don't accuse someone of something unless you are quite sure. Its just not polite.
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I checked tangent's page at http://www.tangentsoft.net/audio/pimeta/
and sure enough, X86Dude is right, it's Pimeta, not pimenta.

It seems like my budget will allow a better amp though, and I don't want to have to upgrade.....PPA? I'm willing to spend the extra cash for it. I was looking around and I found this one built by a guy named karlosak on the www.head-fi.org forums.
front01.jpg

http://www5.head-fi.org/forums/showthread.php?s=&threadid=52507

How much could you quote me for one like that?
 
That is the correct name so please don't accuse someone of something unless you are quite sure. Its just not polite.
Click to expand...
Quite sure?
Umm, maybe you should actually check the links you post more thoroughly.
In case you still don't believe that I am "Quite sure" maybe a picture will help convince you. :rolleyes:
Pi.jpg



I could very easily sell these prebuilt, but I thought allowing people to spec them would be much nicer to them. Everyone has different applications.
Click to expand...

I don't care how you try to justify it this thread is still in violation of many of the rules layed down in the sticky for this section.
Maybe you need a little help there to......
These are now in the rules, watch yourself or be relieved of your posting privileges.

No Shouting.
No flaming or in-before-the-lock posts.
No "contest or giveaway" threads.
No alcohol, tobacco, firearms, or pornography are to be sold here.
No "Group Buys" If you do not own it, you can't sell or trade it.
No "services" allowed. (Ex. I can build xxx for you @ xxx each)
No Dealers or Vendors. Rule Exception 1 If you have a great deal to bring to hardforum members, please email me [email protected] with what your would sell and we will either approve or disapprove your request for such a thread. If you have a great deal, we won't stop you from sharing with our members, but You must be legitimate.
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You reinforce the whole basis of this thread even further in your last reply....

I'm just building people amps to their specs. The price falls where it may, and I am not making a killing off these. All I'm asking is a very reasonable builder's fee, cause it does take a good amount of time to put these together and finish them into a nice, quality amp. In my first post I posted my pricing structure. Its linear, not exponential or logarithmic. I charge you (parts + labor + ship ). Its pretty simple, and I think very fair. Hopefully you'll agree.
Click to expand...
After reading that quote and your initial post I still don't see where you are offering anything for sale here.
You are offering a service.

The rest of your reply is nothing but a bunch of self serving rhetoric that I won't even begin debating with someone that has not even built one of these amps.
But I will tell you that since the first of the year I have built 23 Pimeta's 6 PPA's 1 Meta Mint and two Cmoys, so I don't think you need to go there with me.
I have so little interest in building Cmoy's that I just refer those clients wishing to purchase one to another builder.
I also think you are not going to get very far if you need to go to Head-fi every time you can't solve a problem on your own.
Case in point, your Amping Shure E3 thread.
Take what I said about the hiss very seriously.
Those cans will hiss like dragons from a poorly built amp. ;)
Good luck with the amp thing.
 
X86,

I never once questioned your skill. You are a quite skilled builder and a veteran DIY'er. I don't know why you are putting me down for asking about the shure question I posted. I have never used a shure headphone. I googled what I could find about them and never saw a problem with them. But the person said they were difficult to amp and I didn't want to just assume he was wrong. My initial hypothesis that there is no problem amping the shure's is so far correct according to the Head-fi people.

I don't know why you are trying to attack me like this. You are right, I mispelled "Pimeta" as "Pimenta". And you knew exactly what I was talking about, you just wanted to try and discredit me. I am still a student, am always learning, and probaly don't know as much as you do. But that does not mean that I'm incompetant like you are trying to make me out to be. I am trying to sell the CMOYs because they are quite decent little amps and don't cost a whole lot. Most of the guys I know on this site don't need the audiophile grade amps like the PPA, pimenta, and the like. They just want something nicer.

I realize you have built a bunch of the different amps, but why does that matter? You did look at the price list I posted right? It was a real pricelist. I don't know why you are just calling it self serving. You challenged why I quoted someone that much and I told you. I'm building these for minimal profits and that shows you I have no idea why you're shooting it down.

I have never put a listing like this up in the FS/FT thread before, and so never was caught by the moderator. I am building a couple amps for people on here already so perhaps they will be the last people I deal with her on the [H]. And I'll just let this thread die.

The way you are attacking me is unprofessional and rude. I try to conduct myself as proper as I know how. That is how it should be.

Just watch the heat X86. You always seemed like a great guy, but now you're just coming off as a thread crapper. And if you really want to get down to it, thread crapping is against the rules too. I have never once flaked on a deal, and have always been on the up and up on my online trading and selling activities. What gives you the right to say otherwise now? I am not a troll, spammer, or thief and I take offense to what you are trying to do to me. If you have a problem with what I'm doing you know I'm online, and you have my AIM SN. Why don't you just ask me so I can explain myself or correct myself?
 
Here is an cmoy I spec'd

Desired Specs:
basic cmoy
larger input caps
no volume
battery operated
blue LED
plastic enclosure http://www.krystalforge.net/headphone_amps/sample_pics_html/cmoy3.htm
trimmer pot to control LED brightness
gain of 4

Parts:

Panasonic NHG 220 µF 16V electrolytic capacitor, radial leads
Yageo 1% Metal Film 1/4W Resistors
Orange Drop .47uF 50 plus volt full size film
OPA2132PA
Blue 3mm LED
2x stereo mini jacks
Radio Shack protoboard
Mini SPDT toggle
Serpac H-65-9V (black)
LED trimmer pot

Price:

Subtotal $36
Labor $15
Shipping (from me to you) $4
Total $55
 
First off I am not attacking you.
I am discussing why this thread violates the rules of this section.
Nor am I being rude or trying to discredit you in any way. I am simply presenting the facts as they appear. All of the comments you posted had no bearing on the points I brought up. I informed Zemo how much an amp that I built cost and nothing more. The whole thing about WTF is a Pimenta was an indication to you that you had made a mistake. Instead of checking that mistake you chose to rebuff it as you saw it even though you know I build these amps. If you had simply left it alone and put one and one together the editing of your site would have been completed and the that point would have slid quietly into history.

Just in case you didn't notice who gave you what advice about building an amp for the Shures message Mister X on AIM some time after 9:00 PM.
See, the funny thing about text based messages is you can take the content any way you want.
As far as you comments about my professionalism go ... tread carefully young man.
Just watch the heat X86. You always seemed like a great guy, but now you're just coming off as a thread crapper. And if you really want to get down to it, thread crapping is against the rules too.
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I just inquired about that. It was reviewed and I was told that everything I have posted was kosher.
I have never once flaked on a deal, and have always been on the up and up on my online trading and selling activities. What gives you the right to say otherwise now? I am not a troll, spammer, or thief and I take offense to what you are trying to do to me.
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Tell me ... at what point did I ever say that you were a troll, a spammer, or a thief? Where did I ever say you flaked out on any deals?
All I have said over and over again is that this thread falls outside of the rules for this section.
You are turning the rest of my comments into whatever you want them to be. If there is ever anything I post that you don't understand simply ask me and I will explain it to you.
If you have a problem with what I'm doing you know I'm online, and you have my AIM SN. Why don't you just ask me so I can explain myself or correct myself?
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I am afraid I don't know that. I am not an a machine that has AIM installed.
But your point is not lost on me, AIM is a double edged sword that cuts both ways. If you had simply asked about my earlier reply all of this would be over and done with.
Instead you chose a less civil route witch was met with a similar reply.
 
I have to agree this is one of the most childish displays ever by a member with 2000 posts. You could of left your response in a pm.


I will gladly take a amp of you grog.

email me well talk [email protected]
 
Originally posted by pipeliner
I have to agree this is one of the most childish displays ever by a member with 2000 posts. You could of left your response in a pm.


I will gladly take a amp of you grog.

email me well talk [email protected]
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Email Sent. Get back to me ASAP with the specs you need.
 
Emailed with minor changes, money on it's way, groggory (as soon as you send an updated price).

X86dude, I don't see "Moderator" under your name, so please either buy an amp, or leave the thread and let THEM do their job. It is NOT your job to crap on peoples threads, it is THEIRS to deal with it as they see fit. Now given the time this thread has been up, I'd say they're probably fine with it. IoWnZa is good about catching these, and if you email groggory, he can get you a basic spec price immediately, so he IS offering a product.

Groggory, to avoid these issues, I'd spec out the basic, altoid tin one, and list it here, and mention then all of your customization options underneath it. That way, there is NO doubt about how good you are and what your intents are.
 
Originally posted by lopoetve
Emailed with minor changes, money on it's way, groggory (as soon as you send an updated price).

X86dude, I don't see "Moderator" under your name, so please either buy an amp, or leave the thread and let THEM do their job. It is NOT your job to crap on peoples threads, it is THEIRS to deal with it as they see fit. Now given the time this thread has been up, I'd say they're probably fine with it. IoWnZa is good about catching these, and if you email groggory, he can get you a basic spec price immediately, so he IS offering a product.

Groggory, to avoid these issues, I'd spec out the basic, altoid tin one, and list it here, and mention then all of your customization options underneath it. That way, there is NO doubt about how good you are and what your intents are.
Click to expand...

check your email....changed are updated
 
Could you spec one out (with cost estimate) for a pair of Sony MDR-7506's?

Thanks!
 
hey grogg, what cost for the PPA I asked about? I was looking around a little more and checked out YOUR headphone ampwebsite......but I noticed the pic I posted from karlosak on the head-fi forums is listed on your website of an amp that you built? Are you Karlosak on head-fi?

Wondering....

-Zemo
 
Originally posted by Zemo
hey grogg, what cost for the PPA I asked about? I was looking around a little more and checked out YOUR headphone ampwebsite......but I noticed the pic I posted from karlosak on the head-fi forums is listed on your website of an amp that you built? Are you Karlosak on head-fi?

Wondering....

-Zemo
Click to expand...

No, on headfi I am groggory. The amps I have shown on my page are built by other people. I put them there to give you ideas for when you're asking for your own amps. I'm working on getting all the links to give proper credit, but its not finished yet.

If there is something you like there though let me know and we'll see about building it to those specs. :) Happy hunting

Oh, as to cost I'll work on spec'ing the PPA. I didn't know you were looking for a bid, thought you were just asking some questions. I'll get those prices to you ASAP though.
 
Hate to sound like an ass, but if you're willing to build these amps to spec, why don't you just take an ad out in the Mall-Fi section over at Head-Fi?

Unless the rules here have changed, if you don't have it in your hand, you can't sell it here. Advertising a custom amp for sale would then be against the rules.

But hey, who knows........You honestly might have better luck going the fleabay route, tho.
 
Groggory,

I found this thread and forum via a head-fi.org thread. You use pictures of the best looking amps on your website from people who im sure gave you no permission, and giving them credit (which i dont see) doesnt make up for it. You speak of professionalism, which isn't apparent given you are using other people's hard work (pictures) in a way that could easily be misunderstood as yours. Im not speaking on behalf of any of the rightful owners of those pictures, but as a fellow builder who finds your practice shoddy.

Ivan C.
 
closed because your offering a service, selling what you dont have and a groupbuy.
 
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