Schematic for Simple headphone amp needed
Hello
Just gone to my Cambridge audio np30 streamer to use it stand alone with headphones and it doesnt have a phone jack. Does anyone have any suggestions for a simple, cheap but very good quality headphone amp. The np30 has rca and optical output. I would like a schematic or a diy kit or ready built, preferably rca in, full size head phone jack and volume control.
Thanks
thyristor44
Hello
Just gone to my Cambridge audio np30 streamer to use it stand alone with headphones and it doesnt have a phone jack. Does anyone have any suggestions for a simple, cheap but very good quality headphone amp. The np30 has rca and optical output. I would like a schematic or a diy kit or ready built, preferably rca in, full size head phone jack and volume control.
Thanks
thyristor44
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what headphones is always the question - unlike loudspeakers they differ by even more orders of magnitude in sensitivity, Impedance
different classes of headphones really need altogether different amps
Headphone Amplifiers - Head-Fi.org Community is the fanboy site - too much so to believe anything said there but they do list just about every headphone amp currently made
different classes of headphones really need altogether different amps
Headphone Amplifiers - Head-Fi.org Community is the fanboy site - too much so to believe anything said there but they do list just about every headphone amp currently made
I realy need the amp to work with any headphones and have good frequency response, low distortion and not cost much. Your examples are still way to expensive for me, I have already spent my budget.
I am thinking I will try to make my own and if possible change the thread title to get a suitable circuit diagram or schematic.
You want a whole lot, and you don't have a clue how to design it.
If you were to try to design it, you would be motivated to parse the requirements more efficiently.
I need a new car. It has to be at least 600 horsepower but get 50+ miles a gallon. It need to be really big but small too. It has to be a station wagon, a sedan, and a pickup all at the same time. It has to be a status symbol but be modest too. I want it to be red, blue, and green all at the same time. And it has to cost only $6000, because that's my budget. Do you think I'm going to find the new car I want?
If you were to try to design it, you would be motivated to parse the requirements more efficiently.
I need a new car. It has to be at least 600 horsepower but get 50+ miles a gallon. It need to be really big but small too. It has to be a station wagon, a sedan, and a pickup all at the same time. It has to be a status symbol but be modest too. I want it to be red, blue, and green all at the same time. And it has to cost only $6000, because that's my budget. Do you think I'm going to find the new car I want?
The closest thing to a "do it all" budget high performance amp can be found on the datasheet of the LME49600. It is a very simple circuit. Use non-inductive metal film resistors (like Vishay-Dale CMF55 series) in the feedback loop and audio path. Use quality capacitors. Use op amp of your choice in the front end (even the humble 5532 gives stellar performance in this circuit at gains of 2.5 or less). You can order everything to build it from Digi-Key for around $60.
Then there's the input attenuator. You can use something basic and inexpensive, or you can pay up for a premium volume control or even a stepped attenuator. And keep in mind that attenuator performance really matters in this application; mismatched volume levels between the channels, drop outs and noise, etc, will be glaringly obvious in this application.
Power supply- to be able to drive 600 ohm cans, a +/- 15 volt supply is recommended. You want a quiet power supply - cost of construction varies and it's up to you to parse cost vs performance.
Then there's the case. I've crammed headphone amps into old router and server chassis. They're free (if you have an electronic recycling dumpster in your community) and they make your project look professional. I've found some really nice cases like this. Or you can put the circuit inside your receiver / amplifier / preamp / tuner chassis if there's space. Or you can pay up for a nice case $$$$$ from a manufacturer like Hammond Custom & Modified Enclosures | Hammond Enclosure Sales and make it look like a custom high end project.
Of course you can build a better circuit than a buffered op amp based circuit, but complexity and cost will quickly increase.
Then there's the input attenuator. You can use something basic and inexpensive, or you can pay up for a premium volume control or even a stepped attenuator. And keep in mind that attenuator performance really matters in this application; mismatched volume levels between the channels, drop outs and noise, etc, will be glaringly obvious in this application.
Power supply- to be able to drive 600 ohm cans, a +/- 15 volt supply is recommended. You want a quiet power supply - cost of construction varies and it's up to you to parse cost vs performance.
Then there's the case. I've crammed headphone amps into old router and server chassis. They're free (if you have an electronic recycling dumpster in your community) and they make your project look professional. I've found some really nice cases like this. Or you can put the circuit inside your receiver / amplifier / preamp / tuner chassis if there's space. Or you can pay up for a nice case $$$$$ from a manufacturer like Hammond Custom & Modified Enclosures | Hammond Enclosure Sales and make it look like a custom high end project.
Of course you can build a better circuit than a buffered op amp based circuit, but complexity and cost will quickly increase.
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That's about your best bang for the buck.
Don't forget the heatsinks. Recommended when run from a 30 volt split supply. Clip on TO220 heatshinks can work with that package.
You can substitute BUF634 for the LME49600 if you want to avoid SMD components. It's available in DIP-8 and TO220 packages.
I hope it works out for you.
What do you think about ebay uk 221354218687That's about your best bang for the buck.
Don't forget the heatsinks. Recommended when run from a 30 volt split supply. Clip on TO220 heatshinks can work with that package.
You can substitute BUF634 for the LME49600 if you want to avoid SMD components. It's available in DIP-8 and TO220 packages.
I hope it works out for you.
or h**p://www.ebay.co.uk/itm/221354218687?_trksid=p2060353.m1438.l2649&ssPageName=STRK%3AMEBIDX%3AIT
Looks as if its built from same circuit.
A good, inexpensive alternative for an input attenuator is to use a linear potentiometer (get a carbon track unit, not a plastic conductor one) and parallel a resistor from the wiper to noise (input) ground. This approximates an "audio" taper attenuator much better than most audio taper potentiometers. Use 1% CMF55 resistors and the tracking will be audibly "perfect." Good values are 100K pot and 12 or 14.7 K resistors. Small PC board potentiometers suitable for this application can be bought at Digi-Key for around a dollar. The only caveat to employing this method is that the input impedance will vary from around 100K to around 7K or so as the pot is rotated. You can measure and observe this effect with a simple ohm meter. You must take this into account if employing an input capacitor (recommended) in front of the potentiometer; if haphazardly chosen, the change in frequency response with potentiometer rotation might be clearly audible.
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I see stuff on ebay that is way cheaper than I could ever build it, and I buy in bulk. I really don't know how they do it.
It makes me wonder if some of the parts are fake. I doubt anything cheap on ebay would use ultra high quality resistors like I do. But that doesn't mean that there aren't some great deals. I really don't know about ebay; I only have very bad experience with it.
I don't see any high frequency supply decoupling caps on that board unless they're on the underside (probably not). They can be added easily enough.
Depending on what parts you already have or how cheaply you can get them, it might be better to just get the bare PCB and build it yourself....
1pcs LME49720NA LME49600 Headphone Amplifier PCB | eBay
You can even use BUF634 on that board if you want.
EDIT: Don't forget some input DC blocking caps if you care about your headphones.
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They must be employed on both the op amp and buffer chips. Underside of board is the best place.
More expensive to do, but almost certainly a better option.
Absolutely. Feedback caps too.
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