I have a Philips Fidelio H2HR, I think 50 Ohm.
The time has come to build an amp, but recently many doubts have arisen reading in this forum. I thought that the famous Cmoy was suitable for me, instead it seems that it is not so. With my old very cheap Sony one day I mounted class A amps with a mosfet. No, I'm sorry, it's not the sound I'm looking for, the highs are too bright, a sound too edgy for my tastes and for my ears that with tinnitus do not digest these frequencies well. Maybe what I'm looking for is not true Hi-Fi? I'm not sure, I like to listen well but it doesn't matter, I don't want to become even more deaf!! Once I asked for the Cmoy with the addition of a buffer but they told me that with the Fidelio it was OVER THE MAX. But the single Cmoy is not really a good amp... I only have a CD player and a computer, I'm not interested in something portable or tiny, nothing commercial, I like DIY. When I was a boy I built a small amp with op amp and bd139-bd140, a schematic taken from a magazine, it sounded exactly like I DON'T want! Instead the best CD player I ever had, the Philips CD960 sounded wonderful, and it only had NE5534, maybe without even the output buffer, but it drove any headphones. Basically a 40 year old Cmoy! Ok, I'm afraid I've tired you... what do you recommend?
Thank you all!!
The time has come to build an amp, but recently many doubts have arisen reading in this forum. I thought that the famous Cmoy was suitable for me, instead it seems that it is not so. With my old very cheap Sony one day I mounted class A amps with a mosfet. No, I'm sorry, it's not the sound I'm looking for, the highs are too bright, a sound too edgy for my tastes and for my ears that with tinnitus do not digest these frequencies well. Maybe what I'm looking for is not true Hi-Fi? I'm not sure, I like to listen well but it doesn't matter, I don't want to become even more deaf!! Once I asked for the Cmoy with the addition of a buffer but they told me that with the Fidelio it was OVER THE MAX. But the single Cmoy is not really a good amp... I only have a CD player and a computer, I'm not interested in something portable or tiny, nothing commercial, I like DIY. When I was a boy I built a small amp with op amp and bd139-bd140, a schematic taken from a magazine, it sounded exactly like I DON'T want! Instead the best CD player I ever had, the Philips CD960 sounded wonderful, and it only had NE5534, maybe without even the output buffer, but it drove any headphones. Basically a 40 year old Cmoy! Ok, I'm afraid I've tired you... what do you recommend?
Thank you all!!
You mean X2HR? 30 ohm, 500mW max, comes out to about 130mA max.
opamps have sound signatures. If you add a buffer that is within the feedback loop of the opamp, the sound signature is largely maintained.
The cmoy was originally a thing conceived of to drive 600-ohm headphones so i don't think it's a great pick for a 30-ohm set.
You might like a Grado RA-1 clone. It's not very dissimilar from the cmoy in concept, but based on the njm4556, which has a very respectable power output.
Cheap as chips to build, at least if you have some large film caps for the input section already:
the default configuration uses a pair of 9v batteries, but you can use an 18v wall wart and a tle2426, or a small 12-18vct transformer and bridge rectifier. Throw one together with the batteries and worry about a wall supply if you like it?
opamps have sound signatures. If you add a buffer that is within the feedback loop of the opamp, the sound signature is largely maintained.
The cmoy was originally a thing conceived of to drive 600-ohm headphones so i don't think it's a great pick for a 30-ohm set.
You might like a Grado RA-1 clone. It's not very dissimilar from the cmoy in concept, but based on the njm4556, which has a very respectable power output.
Cheap as chips to build, at least if you have some large film caps for the input section already:
This is my first project and i think it is best project to start with and learn. I found sch of this amp on internet but it only shows one channel. I have no clue how to recreate schematic from picture so i created my own. Am I doing this right or did I make any mistakes? Thanks 🙂
I have left out pot and input caps because they are going to be offboard.
Finished Grado RA-1 Clone:
...
I have left out pot and input caps because they are going to be offboard.
Finished Grado RA-1 Clone:
the default configuration uses a pair of 9v batteries, but you can use an 18v wall wart and a tle2426, or a small 12-18vct transformer and bridge rectifier. Throw one together with the batteries and worry about a wall supply if you like it?
On the Grado, divide all the resistors and pot values by ten. The pot should be a linear stereo type.
The capacitor can remain the same film type, or else use a 10uF bipolar UES electrolytic.
The capacitor can remain the same film type, or else use a 10uF bipolar UES electrolytic.
I'm relatively certain that the pot should be logarithmic taper.
I'm not sure dropping the resistor across the input to 10k is a great idea. This is a bipolar input opamp so it's not quite as well-behaved as the jfet parts.
I'm not sure dropping the resistor across the input to 10k is a great idea. This is a bipolar input opamp so it's not quite as well-behaved as the jfet parts.
The resistor loading the wiper converts the linear taper to a quasi-log taper.
Linear stereo pots with the resistor loading will track much better than most log stereo pots.
Lower DC resistance at the op amp input is better, particularly for bipolar types.
Linear stereo pots with the resistor loading will track much better than most log stereo pots.
Lower DC resistance at the op amp input is better, particularly for bipolar types.
For a noob like me, the only difference I see between the Grado and the Cmoy is just the resistor values. However I think I found an amp that people speak well of. O2
Any type of resonance or frequency response peaking that would be discomforting in high frequency.
Is usually the actual transducer or headphone.
There is plenty of instances or known anomalies that happen with many headphones. Being directly on the ear makes
the ear even more sensitive.
How notable it is depends on the music and recording.
Amplifiers are pretty neutral aside from all the magic talk in marketing.
If opamp driven headphone amp is magical for you. A op amp with additional transistors to drive more current no big deal.
Transistors enclosed in feedback path have little effect, sounds like same op amp with more current drive.
If load is 600 ohms, high current opamp can directly drive, distortion to be expected.
Buffer still helps even lower distortion.
If load is 50 or 30 ohms, need more current. Add buffer in feedback loop.
Opamp sounds same or even less distortion. just more current.
Distortion is Distortion, not warm or pleasing gimmick
What comes in is not what comes out.
Extremely low distortion, nothing What comes in is what comes out.
Very low distortion from .001% to even .0001% is possibly with opamp and current buffer.
No class A magic, auto bias or super rare unobtainable transistor needed.
Low distortion buffer very easy to make.
Amplifier has distortion or doesnt, power suppply is not noisy or is. = the end
Any harsh peaking resonance, or fatigue in frequency response is headphone, not amp.
Bd139/140 more than fine, cant hear. Is headphone or recording.
if 5534 is amazing magical opamp, good add buffer for 30 to 50 ohm loads.
BD139/140 is " bad" oh well use another transistor that does same thing, different name.
Insisting that is problem, waste of time. Arguing what magical opamp is better, also waste of time.
Has enough current to drive load , or doesnt. Add buffer, buffer no hear, distortion lower than recording or headphone.
Is usually the actual transducer or headphone.
There is plenty of instances or known anomalies that happen with many headphones. Being directly on the ear makes
the ear even more sensitive.
How notable it is depends on the music and recording.
Amplifiers are pretty neutral aside from all the magic talk in marketing.
If opamp driven headphone amp is magical for you. A op amp with additional transistors to drive more current no big deal.
Transistors enclosed in feedback path have little effect, sounds like same op amp with more current drive.
If load is 600 ohms, high current opamp can directly drive, distortion to be expected.
Buffer still helps even lower distortion.
If load is 50 or 30 ohms, need more current. Add buffer in feedback loop.
Opamp sounds same or even less distortion. just more current.
Distortion is Distortion, not warm or pleasing gimmick
What comes in is not what comes out.
Extremely low distortion, nothing What comes in is what comes out.
Very low distortion from .001% to even .0001% is possibly with opamp and current buffer.
No class A magic, auto bias or super rare unobtainable transistor needed.
Low distortion buffer very easy to make.
Amplifier has distortion or doesnt, power suppply is not noisy or is. = the end
Any harsh peaking resonance, or fatigue in frequency response is headphone, not amp.
Bd139/140 more than fine, cant hear. Is headphone or recording.
if 5534 is amazing magical opamp, good add buffer for 30 to 50 ohm loads.
BD139/140 is " bad" oh well use another transistor that does same thing, different name.
Insisting that is problem, waste of time. Arguing what magical opamp is better, also waste of time.
Has enough current to drive load , or doesnt. Add buffer, buffer no hear, distortion lower than recording or headphone.
They're both noninverting opamps, but the 4556 and 2134 are pretty different in their characteristics. The 4556 can sink a lot more current, for one thing. Since it's a bipolar part with relatively high input currents, you have to be more careful with the feedback loop to prevent a DC offset.
The O2 is a very respectable amp. Uses the 4556 as an output buffer.
Thanks for the explanation!
A question: I only have "normal" op-amps like JRC4558, NJM4558, NE5532 and OPA2134. Please, can you tell me which of them I can use as an amplifier and which as a buffer? When I was young I remember electronics magazines raving about the NE5532 as both an amplifier and a buffer, and it is also stable at unity gain. Thanks!
A question: I only have "normal" op-amps like JRC4558, NJM4558, NE5532 and OPA2134. Please, can you tell me which of them I can use as an amplifier and which as a buffer? When I was young I remember electronics magazines raving about the NE5532 as both an amplifier and a buffer, and it is also stable at unity gain. Thanks!
the 4558 is best left to guitar effect pedals that you want to sound, well, that way.
The ne5532 / ne5534 was a big deal when it was new. And there have been designs that used them as buffers -- I used to have some nakamichi 'multimedia' speakers that just used like 20 of them in parallel.
At this point it's very old tech, and very noisy and not very transparent compared to even chips like the njm2068, which is cheaper.
by the way, jrc and njm are the same thing. japan radio corp and nishinbo micro devices are the same company, it's just a re-brand.
the njm4556 is, afaik, unparalleled in terms of current sinking performance at the price.
The opa1656 from Ti is better in every way except it costs $2.56/ea and only comes in surface mount packages, where the 4556ad is $1.08.
The O2 was a stunt by a talented, anonymous electronic engineer who wanted to demonstrate what can be done with cheap parts and actual design chops. If "nwavguy" was ever named, I never heard who they are. They went silent and the blog stopped getting updates. Presumably they got a job? I'm sure people have tried using modern, faster, lower-noise parts in them. But it's not necessary.
The opa2132/2134 was the greatest audio opamp of like 20 years ago? They're fine for the amplification stage, I don't think they drive low-z headphones well without a buffer, and i find that they have a somewhat colorful sound signature.
The ne5532 / ne5534 was a big deal when it was new. And there have been designs that used them as buffers -- I used to have some nakamichi 'multimedia' speakers that just used like 20 of them in parallel.
At this point it's very old tech, and very noisy and not very transparent compared to even chips like the njm2068, which is cheaper.
by the way, jrc and njm are the same thing. japan radio corp and nishinbo micro devices are the same company, it's just a re-brand.
the njm4556 is, afaik, unparalleled in terms of current sinking performance at the price.
The opa1656 from Ti is better in every way except it costs $2.56/ea and only comes in surface mount packages, where the 4556ad is $1.08.
The O2 was a stunt by a talented, anonymous electronic engineer who wanted to demonstrate what can be done with cheap parts and actual design chops. If "nwavguy" was ever named, I never heard who they are. They went silent and the blog stopped getting updates. Presumably they got a job? I'm sure people have tried using modern, faster, lower-noise parts in them. But it's not necessary.
The opa2132/2134 was the greatest audio opamp of like 20 years ago? They're fine for the amplification stage, I don't think they drive low-z headphones well without a buffer, and i find that they have a somewhat colorful sound signature.
For a chip released in 1979, 20 years is not old. They're old stock sure, but i'm pretty sure the original fab for the 5532 was shuttered in 1992?
