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Old 10th January 2013, 07:55 AM   #41
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So what gauge magnet wire is on there now and what gauge would you suggest? I might have some left over from the tuner I made for my crystal radio 50 years ago.
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Old 11th January 2013, 10:14 PM   #42
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Does anyone have a manufacture part # for the 2.2uf input caps and OPA2132 op amps?

I'm trying to place my order with mouser today. I already have all other parts in my cart just making sure I get the right parts.

Thanks in advance.
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Old 12th January 2013, 09:08 PM   #43
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Originally Posted by Redshift187 View Post
My second mod was to remove the volume op-amp and almost all of the components around the op-amps, and wire the volume pot as a regular attenuator.

I removed R42 and R43 (to the right of the tone/direct switch, behind the treble pot) to disconnect the tone circuit from the switch, then wired the pot to the "tone" side of the switch. Now "tone" = on, "direct" = mute. I did it this way because in order to use the "direct" side of the switch, I would have had to remove the resistors under the switch, which were too hard to get to. I grounded the one end of the volume pot to the through-hole where the ground strap for the pot is connected.

This mod also improved clarity, and gave me more useful volume control range.

Red--

Which is the volume opamp and what things did you remove?

Thanks
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Old 13th January 2013, 02:50 AM   #44
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Default CMoy?

Hey,

Red, Sofaspud, Bare.... even if people change the opamp in line with the volume, doesn't this still just end up an amp'd CMoy?
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Old 13th January 2013, 08:21 AM   #45
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I'm not sure I understand the question.
I swapped the stock 4558's with a couple SOIC LM833's I had on hand. When the volume was turned way up, where the distortion began getting extremely harsh to the ears, it seemed to improve the sound significantly. I don't have any measurements, and I'm not even certain of the input configuration, for my amp. But any improvement there is worth it IMO so I've no regrets about the mod.
Also IMO... the credit to Chu Moy is that he designed and web-published a great sounding, easy to build, readily modifiable portable DIY headphone amplifier project. Maybe more popular than he ever imagined it would be. So, his credit is well deserved, but I'm not prepared to call every op amp gain block a "CMoy."
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Old 13th January 2013, 05:04 PM   #46
Bare is offline Bare  Canada
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Quote:
Originally Posted by Hat Alto View Post
So what gauge magnet wire is on there now and what gauge would you suggest? I might have some left over from the tuner I made for my crystal radio 50 years ago.
Simply does not matter the wire gauge ONLY the number of winds on it.
Mh value is derived from # of winds, Amp capability from the thickness /gauge of the wire used. Most any Electronics shop carries mag wire Or if seriously frugal; unwind a toy motor armature.
But it has to fit on fairly neatly.. so coathanger thick could be problematic :-)
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Old 13th January 2013, 05:10 PM   #47
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Originally Posted by tamasic1 View Post
Hey,

Red, Sofaspud, Bare.... even if people change the opamp in line with the volume, doesn't this still just end up an amp'd CMoy?
What is a C'moy?
All I know is to remove 'at least' those junky opamps, on the right hand side of the board, as these remain partially in the circuit, unless physically removed
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Old 13th January 2013, 09:33 PM   #48
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Originally Posted by bitperfectq View Post
Does anyone have a manufacture part # for the 2.2uf input caps and OPA2132 op amps?

I'm trying to place my order with mouser today. I already have all other parts in my cart just making sure I get the right parts.

Thanks in advance.
OPA2132 IS the manufacturer's part number. As for 2.2uF caps, well that depends on what you want and how well you want it to fit the stock location. You could get electrolytics like what is already there, polyester, polypropylene, ceramic, etc etc. There are then numerous manufacturers of each of these types.
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Old 13th January 2013, 09:36 PM   #49
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Originally Posted by makingmoney View Post
Red--

Which is the volume opamp and what things did you remove?

Thanks
U2 is the volume opamp I believe. Look at post 7 for a picture of all the stuff I removed.

You can safely remove all the components clustered around the opamps. But you'll need to rewire the input in some manner (with or without the volume control).
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Last edited by Redshift187; 13th January 2013 at 09:38 PM.
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Old 19th January 2013, 03:23 AM   #50
lwj5 is offline lwj5  Singapore
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Oh no I was trying to change parts C42, I thought it was a 0.1uF cap... now that channel became a low-pass filter or high-pass filter.

Anyone know the correct capacitance for C42 and C43.

Just to check C31 and C30 are 2.2uF right?
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