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-   -   OP-AMP HEADPHONE AMP SUGGESTIONS NEEDED (http://www.diyaudio.com/forums/chip-amps/183205-op-amp-headphone-amp-suggestions-needed.html)

horizonrays 15th February 2011 01:24 PM

OP-AMP HEADPHONE AMP SUGGESTIONS NEEDED
 
Hey folks ,I am wondering which circuit to consider :confused: , may be you people can help me !
here are the links to the circuit schematics , :D
Headphone Amplifier
HeadWize - Project: Build This High Quality Headphone Amplifier by Earle Eaton
HeadWize - Project Addendum: Build This High Quality Headphone Amplifier by Earle Eaton
Please tell me which circuit to use and why , may you can list the pro and cons of each of them ... thanks . :shy:

nightanole 15th February 2011 02:24 PM

All these are basically the same, bypolar 15v power supplies, and opamps with their outputs buffered.

Ill ask a few questions.
Do you have a power supply allready?
Do you want to bread board only or will you by a pcb?
What are your headphones? Big diff in requirements for 250ohm units, 32 ohm units, etc.
Tubes, no tubes?

Id check out out the popular pcbs.

The Minił Portable Stereo Headphone Amplifier
Ventus
How to Build the CMoy Pocket Amplifier
PIMETA v2 Headphone Amplifier
DIYForums.org
Pete Millett's DIY Audio pages


Then there are the bread boarders:
DIY IRF610 MOSFET Class-A Headphone Amplifier Project
NP-100v12: DIY 12AU7 (ECC82) Tube / IRF510 MOSFET Headphone Amplifier
GWado - DIY CMoy / Grado RA1 Headphone Amplifier

nightanole 15th February 2011 03:09 PM

Heres a kit based on your 3 original designs.

Current boosted diamond buffer preamplifier stereo kit - eBay (item 320636258667 end time Feb-27-11 08:11:33 PST)

horizonrays 15th February 2011 03:20 PM

night , i use 32 ohms Philips headphone , yew i have power supply , -/- 15v first i will do it on breadboard , then i will etch the pbc , and yes it's just solid state , no tubes , just op-amp and transistors , well you , as far as i understand both headwirez project is same , just different transistors , but rod elitot's design is bit different thanks for the resources , i am looking at them , in the meanwhile , may be some one will be able to tell me exact difference between both schematic .

horizonrays 15th February 2011 03:23 PM

nightanole ,
i was having trouble understanding the circuits how they work , now you posted , yet another more circuit , :headbash:

someone explain how the transistor are working in these circuits ,

the only circuit i understood is headwize circuit , someone explain me the working of ebay circuit and also the rod eliot's circuit .. :yawn:

nightanole 15th February 2011 11:23 PM

Ebay and rods are almost the same. They are just standard opamp setups that have a buffered output. I think with headphones you dont need a buffer, but some people want them. I just dont see the point of making an amp with 10x more power then what the cans can take. Id rather have a single high current opamp.

So like i said. Standard opamp setup with a +-15v (really +-6v would be enough to blow your cans)

signal comes in, Gets rid of dc offset with a cap in the audio path. Then goes to the opamp for a voltage gain. Then the opamp "plays" into a several K load of the output buffer. The output buffer then takes the load off the opamp and drives the headphones.

Personally I would try a cmoy first. it does everything the other amps do, its just not as complex. Take away the output buffers and lower the power supply voltages alittle and you have a cmoy.


If you want to try something different. Here is another buffered circuit that is pretty simple and ment for your cans.

How to build the Apheared 47 Headphone amplifier for Grado Headphones

horizonrays 15th February 2011 11:35 PM

Quote:

Originally Posted by nightanole (Post 2470259)
Ebay and rods are almost the same. They are just standard opamp setups that have a buffered output. I think with headphones you dont need a buffer, but some people want them. I just dont see the point of making an amp with 10x more power then what the cans can take. Id rather have a single high current opamp.

So like i said. Standard opamp setup with a +-15v (really +-6v would be enough to blow your cans)

signal comes in, Gets rid of dc offset with a cap in the audio path. Then goes to the opamp for a voltage gain. Then the opamp "plays" into a several K load of the output buffer. The output buffer then takes the load off the opamp and drives the headphones.

Personally I would try a cmoy first. it does everything the other amps do, its just not as complex. Take away the output buffers and lower the power supply voltages alittle and you have a cmoy.


If you want to try something different. Here is another buffered circuit that is pretty simple and ment for your cans.

How to build the Apheared 47 Headphone amplifier for Grado Headphones


actually i want to know what happens in those circuits , after opamp ,
since op-amp amplifies the signal , and send it to transistor as most opamp cannot provide enough current to driver the transistor ,

but in the circuits i posted , two different approaches has been used , ib both circuits , transistors are given signal in two different way from opam, and actually i want to know the difference between them , :headbash:

nightanole 15th February 2011 11:49 PM

They are not fed diff, they are just drawn diff. Rods and earle's are almost the same. The only diff is how they are drawn.

Rod cap coupled the outputs of the opamp, and dc coupled the outputs of the buffer.
Earle dc coupled the outputs of the opamp, and cap coupled the outputs of the buffer.

Redraw both circuits without caps in the audio paths, and no power supplies. Both circuits will be the same other then rod's bias diodes, and earle's output resistor.

I dont like either one of them because they have caps in the audio path after the signal has been amplified. I like to have just 1 cap in my whole audio path, in between my source and amp to prevent dc offset. Earle decided that a electrolytic the size of a battery would be good for an output for some reason.

I can blow up any set of cans 64 ohm or lower with my unbuffered amb mini3. it puts out 300mw into 32 ohms with 1 opamp for both channels. Why dont you axe their power supply. use your own design, and use their schematic and parts selection for the opamp and gain resistor values?

horizonrays 15th February 2011 11:55 PM

thanks for the answers .

qusp 16th February 2011 02:24 PM

3 Attachment(s)
i dont like caps anywhere except maybe filters in feedback, but then i drive all my cans balanced so offset as long as its symmetrical is almost meaningless. i disagree about not needing a buffer, i use very low impedance headphones, so presenting very low output z is key. there are some nice new chips that will do it on their own if implemented well though, so i guess you are right, just depends on components used.

like this iv stage with gain i'm using in my portable dac/headamp, using +/-13vdc from lifepo4 battery pack to power these 2 opa1632dgn, with powerPAD it will output enough current without buffer.

still a very simple circuit, i went a bit crazy with parts selection, but the only cap in the signal path in the whole build is those relcap RTE polystyrenes to filter hf junk; the others are for decoupling the supply. there is another set of resistors underneath the vishay mkp1837 box caps, so there is multiple feedback, one for gain and one for filter. i omitted the output filter to keep damping high as possible

this is not my desig, its an early ackodac iv stage that i have modified to suit my purposes; these SuSy chips sound very well indeed and while the smd zfoils are not as fiddly as i thought, i sure needed a stiff drink before hand


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