Need some pointers for my first amp build

[Rainmaker91]

   
 
Phillips?  You should read more closely: they are Panasonic, a Matsush*ta company product. Actually, they changed their name to Panasonic Corporation,* but maybe that means they're really based in Detroit-san or New Yorkyo.

  For that matter, the Nichicons that I also mentioned are also Japanese, but whatever.
 
You will need to change the LED and/or resistor if you go with 2x 9V.  Keep in mind that all re-chargeables are much less voltage than alkaline.  So when you're talking about a re-chargeable 9V battery, it could only be 7.2V or 8.4V.  I can't speak for Lithium, but if you go with Ni-Cads or NiMH, just look in my signature for "Trickle Chargers for the old PIMETA."  That will work on a CMoy, too.
 
Yes, Fred's tutorial is good and apropos, too.  Follow it if you want, it'll work fine.

 
 
 
* Maybe because internet filters would keep deleting parts of their company name.

Totally saw the wrong name on that cap, the fact that it's panasonic makes much more sense to me (for some reason I have always had a problem telling hich one is which since I was little, which is carzy since they are very different). Anyway, yeah I'll be coing with the panasonics then
 
As for the LED voltage... are you sugesting I set them up in series instead of parallel? can the amp handle double the voltage? or am I missing something here.
 
While the charger is something I really want, it's something that I might have to look in to at a later date. I'll make sure to leave enough space in the case I'm making for such an adition. 

 

[Rainmaker91]

  Since you're already going to pay for shipping, I'd go ahead and get the TLE2426 rail splitter if you're going to be using the battery.  
 
And for the C2 cap, I'd look for something in the 0.3-1.0uF range since space isn't going to be that tight for you.
 
 
Jeg reiser til Norge i August.  Vi har et hytte i Kragero.  My local store carries that board shown on Tangent's site.  I'll plan on bringing one or two along (they're $2 each).  I can drop it in the mail for when you decide to build your CMoy V2.0

I'll see about adding the rail splitter (I assume this one will work), as for ordering a ton of stuff when first paying shipping... Normaly I would do that, but there is a limit on import goods that says everything under 350NOK including shipping is tax free. Anything over that sum and we are looking at paying 25% tax on the items as well as a flat customs fee on about 15USD. While I would not call myself cheap, it would be a bit annoying having to pay about double the price jsut because I came a few cents over the limit.
 
Regarding the C2 cap, I really have no clue what to look for. Would a larger cap be more benefitial than one set at 0.1uf?
 
As for the last matter... really not sure what board you mean, is it the radioshack protoboard? or are you refering to a different one. 

 

[30Cal]

Yes, I was talking about the radioshack protoboard.
 
The cap C2 on the input, along with the resistor R1 act as a hipass filter.
 
http://tangentsoft.net/audio/cmoy/tweaks.html#caps
 
 
Something like this, perhaps?   Not to large (17.5mm).  Maybe tomb can chime in.  Choosing parts isn't my strong suit.
http://www.mouser.com/ProductDetail/Vishay-BC-Components/BFC241673304/?qs=sGAEpiMZZMv1cc3ydrPrF6b39BhxIu4vmDuaLr%2fXsbg%3d

 

[tomb]

 

  Since you're already going to pay for shipping, I'd go ahead and get the TLE2426 rail splitter if you're going to be using the battery.  
 
And for the C2 cap, I'd look for something in the 0.3-1.0uF range since space isn't going to be that tight for you.
 
 
Jeg reiser til Norge i August.  Vi har et hytte i Kragero.  My local store carries that board shown on Tangent's site.  I'll plan on bringing one or two along (they're $2 each).  I can drop it in the mail for when you decide to build your CMoy V2.0

I'll see about adding the rail splitter (I assume this one will work), as for ordering a ton of stuff when first paying shipping... Normaly I would do that, but there is a limit on import goods that says everything under 350NOK including shipping is tax free. Anything over that sum and we are looking at paying 25% tax on the items as well as a flat customs fee on about 15USD. While I would not call myself cheap, it would be a bit annoying having to pay about double the price jsut because I came a few cents over the limit.
 
Regarding the C2 cap, I really have no clue what to look for. Would a larger cap be more benefitial than one set at 0.1uf?
 
As for the last matter... really not sure what board you mean, is it the radioshack protoboard? or are you refering to a different one. 

 
That's an SMD TLE chip.  You don't want to mess with that on a perf board and as a beginner.  Buy something you can plug-in at this point, maybe like this:
http://www.mouser.com/ProductDetail/Texas-Instruments/TLE2426CP/?qs=sGAEpiMZZMuBck1X%252b7j9fMUpdHUjT1avQcho9x7s2ys%3d
 
That would also mean another opamp socket.  If it was me, though, I'd forget that.  Just get the basic CMoy built, enjoy the achievement and the sound.  Then move on to upgrades if you like.
 
Hobbies are littered with the remains of people who never continued because they bit off more than they could chew to start out.

 

[tomb]

Regarding the LED, I simply meant that if you went with 2x 9V batteries, you have a different working voltage (~18VDC or 9VDC after the rail splitter).  That means the resistor must be sized at 9V, not 4.5V to power the LED.

 

[Rainmaker91]

  Regarding the LED, I simply meant that if you went with 2x 9V batteries, you have a different working voltage (~18VDC or 9VDC after the rail splitter).  That means the resistor must be sized at 9V, not 4.5V to power the LED.

Did I size it at 4.5v earlier? if so I had no idea, I just put in the variables in the calcuator and trusted that would work. Wouldn't I just be combining the red wires and the black wires to get a paralell setup, then simply run it the way shown in the schematic? Or would I need something else in the setup?
 
As far as I know that would give me 9v in for the LED wich I restrict by applying a resistor that should be sized for 9v in and the LED in use (based on mA and V), which in this case with an LED @3.2v and 20mA would be a resistor @330Ohm and 1/4w.
 
I could be wrong but that's at least how my inexperienced eyes read it. Also the caps I linked to earlier would they be sufficient or do would you sugest other ones.
 
Edit: Just found out the Alps pot is no longer in stock so I found an alternative from bourns that I think should work

 

[30Cal]

The cap you linked in the post above will certainly work fine.  The tangent website says that 0.1uF is not ideal as the bass cut-off is marginal.  A larger capacitance will push the cutoff lower and help your bass, but they get pretty large in a hurry, so look closely at the physical size.  If you can fit a bigger cap in there, then by all means, go with a 0.3 or 0.47uF.  I wouldn't worry about the tolerance; even a 20% variation isn't going to mean much to your ears down there.  I think I used something along these lines:
 
 
http://www.mouser.com/ProductDetail/Vishay-BC-Components/BFC247936474/?qs=sGAEpiMZZMv1cc3ydrPrF6b39BhxIu4vqq5mGEZN4hQ%3d
or
http://www.mouser.com/ProductDetail/Panasonic/ECW-FD2W474P1/?qs=sGAEpiMZZMv1cc3ydrPrF5m%252btQWx%252bSdKfJy4ilTLoEY%3d
 
 
On the pot, keep an eye on the shaft length and type (flat or knurled) and make sure your knob will still fit.

 

[Rainmaker91]

  The cap you linked in the post above will certainly work fine.  The tangent website says that 0.1uF is not ideal as the bass cut-off is marginal.  A larger capacitance will push the cutoff lower and help your bass, but they get pretty large in a hurry, so look closely at the physical size.  If you can fit a bigger cap in there, then by all means, go with a 0.3 or 0.47uF.  I wouldn't worry about the tolerance; even a 20% variation isn't going to mean much to your ears down there.  I think I used something along these lines:
 
 
http://www.mouser.com/ProductDetail/Vishay-BC-Components/BFC247936474/?qs=sGAEpiMZZMv1cc3ydrPrF6b39BhxIu4vqq5mGEZN4hQ%3d
or
http://www.mouser.com/ProductDetail/Panasonic/ECW-FD2W474P1/?qs=sGAEpiMZZMv1cc3ydrPrF5m%252btQWx%252bSdKfJy4ilTLoEY%3d
 
 
On the pot, keep an eye on the shaft length and type (flat or knurled) and make sure your knob will still fit.

Ill have a look at the caps then, size size really is no issue Ill probably go with a 0,47uf cap then. The total price for it all is racking up though, so I will probably try to get some Panasonic and wima caps  since the vishay seem to be a bit on the expensive side. Ill get the board and some other stuff (if i forget anything) locally since i need to keep the cost down a bit now and would rather get the quality parts internationally since they are not as readily available localy, or at least not cheaply (for example vishay resistors cost 10x more localy, but other china brands are about the same price).

 

[Rainmaker91]

In other news...
 
Just got the schematic for the china DIY amp I ordered earlier. No clue what any of it means, but I'm guessing I may be able to use parts from it in other projects.

 

[Rainmaker91]

Got the basket all ready to order now, just need to check with you guys before pulling the trigger. I added R3 resistors all the at the values of 1kOhm, 2kOhm, 2.5kOhm and 3.3kOhm, hoipefully that will be enough because those RN resistors rack up the price fast (barely under the order limit atm).
 
Take a look:

 

Mouser No:	71-RN55D3301F
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[td=colspan:2] RN55D3301FB14 [/td] [td=colspan:2] Vishay [/td] [td=colspan:2] Metal Film Resistors - Through Hole 1/8watt 3.3Kohms 1% 100ppm [/td] [td=colspan:2] No [/td] [td=colspan:2]

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Also, it just hit me that since space isn't an issue, wouldn't it be far better to use one of these: http://no.mouser.com/ProductDetail/Eagle-Plastic-Devices/12BH382A-GR/?qs=sGAEpiMZZMt13fpse6CWDStRKTlfQlMHKaGGTOd4Zv4%3d rechargable AA batteries are both cheaper and better than 9v ones. And combining 8 of them in series would give me 9.6v.

 

[tomb]

JMHO, but you're still better off with 2x 9V than AA's.  The CMoy is not going to be able to handle much current.  It's more for high-impedance phones, to be truthful.  If you want something with enhanced current, this is a better design:
http://benfeist.com/how-to-build-the-apheared-47-headphone-amplifier-for-grado-headphones/
 
Even then, you're not going to enjoy a lot of the current capability available from the AA's.  Remember also, if you are still wanting to re-charge them, you have reduced voltage.  That 8-cell holder will equate to 9.6V, not 12V.  As mentioned before, though, it could be worse with 9V re-chargeables.  There are a lot of 9V re-chargeables out there that are only 7.2V (only 6 cells).  The better ones are at least 8.4V (7 cells).  The 7-cell ones are often slightly larger than a regular 9V alkaline, too, further complicating matters if you are designing a case.
 
You have one RN60 resistor up there you should change back to a RN55.  The RN60 is twice as big and has 2x the power rating.  You don't need that.  I'd also get rid of the Xicon, too, just to be consistent.
 
Your knob is a specific dial knob with numbers made for a face plate.  You might be better off with a simple cylinder-type knob, instead.
 
About the LED - voltage is not really the design constraint, it's current.  You use the infamous Ohm's Law to determine the resistor at the operating voltage that will give you the desired current.  A normal LED usually has a current max of 20ma.  Good practice is to size the resistor for about half of that, or 10ma.  In the case of the CMoy, I was thinking before that the LED was after the rail splitter - it is not.  So, you have the full voltage of the battery(ies) that must be taken into account for the sizing resistor.  Rearranging the equation for the LED resistor, you have R = V/I.  If V = 9V and I = 0.010A, then you have R = 900 ohms.  900 ohms is an inconvenient resistor value.  If we pick 1K, the resulting current is I = 9V/1000ohms, or 9ma - close enough.
 
Tangent shows 2x 9V in his schematic.  If we start with that voltage, then the resistor is R = 18/0.01, or 1800 ohms.  This makes sense, because the voltage is 2x, so the resistor is also 2x the previous example.  Tangent specs a 10K resistor, so the current is down around 1.8ma.  In this case, he's probably sizing that way for two reasons: 1) it's supposed to be a power-on indicator, not a tube light or flashlight and 2) current is limited in the design anyway, you don't want to be burning up a lot of current in the LED that could be used by the headphones - or have the LED running down the batteries.
 
Whichever you decide, maybe you have enough info there to see what's going on and size the resistor for what you want in your situation.

 

[Wiljen]

Why has nobody tried looking at using IMR cells like are common for vaping?   I would think a pair of 2600mAh 18650s in series would last forever before needing to be recharged with the very low drain the CMOY or other small SS designs have.   Even if you went to the 16340 (CR123 size roughly the same as 9 volt cell) they would have a better mAh than running anything alkaline and you get rid of the possibility of leakage that is always present with alkaline batteries.

 

[tomb]

  Why has nobody tried looking at using IMR cells like are common for vaping?   I would think a pair of 2600mAh 18650s in series would last forever before needing to be recharged with the very low drain the CMOY or other small SS designs have.   Even if you went to the 16340 (CR123 size roughly the same as 9 volt cell) they would have a better mAh than running anything alkaline and you get rid of the possibility of leakage that is always present with alkaline batteries.

Sounds reasonable.
 
However, my personal vote would be to just use alkalines.  A CMoy will still run forever just using alkalines.  It's not like it's got buffers biased into Class A or similar.  I don't think he's casing anything up, either, so leakage is probably not an issue.  Often someone will build a CMoy, gain the needed confidence to try something more sophisticated, and move on before the alkaline batteries are drained, anyway.

 

 

[Rainmaker91]

  JMHO, but you're still better off with 2x 9V than AA's.  The CMoy is not going to be able to handle much current.  It's more for high-impedance phones, to be truthful.  If you want something with enhanced current, this is a better design:
http://benfeist.com/how-to-build-the-apheared-47-headphone-amplifier-for-grado-headphones/
 
Even then, you're not going to enjoy a lot of the current capability available from the AA's.  Remember also, if you are still wanting to re-charge them, you have reduced voltage.  That 8-cell holder will equate to 9.6V, not 12V.  As mentioned before, though, it could be worse with 9V re-chargeables.  There are a lot of 9V re-chargeables out there that are only 7.2V (only 6 cells).  The better ones are at least 8.4V (7 cells).  The 7-cell ones are often slightly larger than a regular 9V alkaline, too, further complicating matters if you are designing a case.
 
You have one RN60 resistor up there you should change back to a RN55.  The RN60 is twice as big and has 2x the power rating.  You don't need that.  I'd also get rid of the Xicon, too, just to be consistent.
 
Your knob is a specific dial knob with numbers made for a face plate.  You might be better off with a simple cylinder-type knob, instead.
 
About the LED - voltage is not really the design constraint, it's current.  You use the infamous Ohm's Law to determine the resistor at the operating voltage that will give you the desired current.  A normal LED usually has a current max of 20ma.  Good practice is to size the resistor for about half of that, or 10ma.  In the case of the CMoy, I was thinking before that the LED was after the rail splitter - it is not.  So, you have the full voltage of the battery(ies) that must be taken into account for the sizing resistor.  Rearranging the equation for the LED resistor, you have R = V/I.  If V = 9V and I = 0.010A, then you have R = 900 ohms.  900 ohms is an inconvenient resistor value.  If we pick 1K, the resulting current is I = 9V/1000ohms, or 9ma - close enough.
 
Tangent shows 2x 9V in his schematic.  If we start with that voltage, then the resistor is R = 18/0.01, or 1800 ohms.  This makes sense, because the voltage is 2x, so the resistor is also 2x the previous example.  Tangent specs a 10K resistor, so the current is down around 1.8ma.  In this case, he's probably sizing that way for two reasons: 1) it's supposed to be a power-on indicator, not a tube light or flashlight and 2) current is limited in the design anyway, you don't want to be burning up a lot of current in the LED that could be used by the headphones - or have the LED running down the batteries.
 
Whichever you decide, maybe you have enough info there to see what's going on and size the resistor for what you want in your situation.

Honestly, the only reason I'm acquiring a dedicated amp for headphones at this moment is to have better control of my new Beyer Dynamic DT 990 Pros (250Ohm), because most of my sources seem to weak to have a proper handle at them on listening level (need to get to 100% to get to listening level on my phone for instance, and at that level I loose significant parts of the soundstage).
 
The reason for the RN60 was simply beacuse it was half the price of the RN55, but if you think I would be better off with the RN55 then I will change that.
 
I see, so the intended design with the batteries was always to run them in series rather than parallel to achieve 18v compared to 9v. In that case I can see that my resistor is way off in size, but I also want to make sure the resistor gets enough current to actually light up.  AS for the Xcion resistor... I simply chose that because the vishay was on backorder, but if I'm going to use a different sized one then I'll see if I can't get a vishay in there.
 
As for the knob... the thing is, I'm actually making the case with a face plate... So that is why I found it practical to have one with numbers on it.
 
 

 
Sounds reasonable.
 
However, my personal vote would be to just use alkalines.  A CMoy will still run forever just using alkalines.  It's not like it's got buffers biased into Class A or similar.  I don't think he's casing anything up, either, so leakage is probably not an issue.  Often someone will build a CMoy, gain the needed confidence to try something more sophisticated, and move on before the alkaline batteries are drained, anyway.

 

I was under the impression that the Cmoy would drain the Alkeline batteries reasonably fast (20 hours of use or so?), but if that is not the case then I may not need to use rechargeable cells.
 
As for casing it up... I will be making a completely closed box for the amp, but I will be making a hatch for the battery compartment (which will be a separate room for convenience).

 

[tomb]

I don't know what the price is of V-D resistors in your country.  We pay 10 cents.  If it's more than that, then there's something special about that particular resistor and you should look elsewhere, which is what you did, I suppose.  Still, that resistor is only 50 cents on US-Mouser.
 
I'm not sure if 20 hours is the time limit on alkalines feeding a CMoy, but I suspect it's really 4 or 5 times that, if not more.  A lot will depend on how much current you let that LED burn.  Otherwise, there's very little being used.  It's been awhile since I had a CMoy, but I don't recall only 20 hours.
 
I built a couple of PIMETAs that I still have.  Those are all solid-state and more or less a buffered-output version of a CMoy.  I have both heavily biased into Class A at the buffers and they will only last about 5-6 hours.  That I understand and remember, but a CMoy at 20 hours sounds wrong.