Just one question - line level and headroom?
I see the sim has 130mV input but consumer level line in could have transients way above this. Unless I’m wrong a consumer level line in should be amp to take a 9Vp-p line in?
I see the sim has 130mV input but consumer level line in could have transients way above this. Unless I’m wrong a consumer level line in should be amp to take a 9Vp-p line in?
Gain is ~11dB (~3.5x) and max output is no more than 10Vpp (3.5Vrms) to stay in reasonable distortion range. Being single ended Class A with a resistive load, it can’t swing much. It’s more of a headphone amp, a preamp input of 2.8Vrms will clip. The 150mV amplitude test case is 1/2 of the amplitude of the peak to peak input for about 1Vpp output, a typical listening level amplitude for average headphones.
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I have a plan , i don't know if it looks good,
I will call it Hakuin Integrated Preamp.
OPA1642 Phono Pre-amp Passive RIAA --> Selector Switch (To Take other input like Aux, CD, Tape) --> Hakuin (to add beautiful sound signature) --> OPA1656 for Baxandall Volume Control.
OPA1642 is chosen for Phono Stage to add bit of bite and flare which OPA1656 lacks.
Is it look good to you , X?
For me , no hurry now , i will take it up in Autumn of next year as i have things like Entrance exams to handle until then.
I will call it Hakuin Integrated Preamp.
OPA1642 Phono Pre-amp Passive RIAA --> Selector Switch (To Take other input like Aux, CD, Tape) --> Hakuin (to add beautiful sound signature) --> OPA1656 for Baxandall Volume Control.
OPA1642 is chosen for Phono Stage to add bit of bite and flare which OPA1656 lacks.
Is it look good to you , X?
For me , no hurry now , i will take it up in Autumn of next year as i have things like Entrance exams to handle until then.
I decided to build my first ever headphone amplifier and after a thorough search on diyaudio, this looked like the ideal candidate. I had an enclosure that I wanted to use for the amp, so I started from the wrong end of the build and tried to fit everything to that enclosure. It was a real 3d puzzle and it even shaped the layout of the boards. This is also the reason why I could not use the Hakuin DBs unfortunately...
I went with 5s lipo battery as the power source. While the initial idea was to use a LDO regulator, I could not wait for the delivery and used a switching regulator that I had. I placed the battery charger into the case as well, so I only connect a power cable when I want to charge it. There are 3 switches, first one connects the charger to the battery as I thought I can disconnect the charger while listening, but I cannot hear any difference when it is connected so it may always stay on. The second one turns on/off the amplifier and the last one connects/disconnects the headphone socket to address the power-on thump issue.
I am listening to this amplifier with Sennheiser HD6XX and a non oversampling dac (tda1387). I do not have anything to compare it against but it sounds amazing. Thank you xrk971 for the design!
I went with 5s lipo battery as the power source. While the initial idea was to use a LDO regulator, I could not wait for the delivery and used a switching regulator that I had. I placed the battery charger into the case as well, so I only connect a power cable when I want to charge it. There are 3 switches, first one connects the charger to the battery as I thought I can disconnect the charger while listening, but I cannot hear any difference when it is connected so it may always stay on. The second one turns on/off the amplifier and the last one connects/disconnects the headphone socket to address the power-on thump issue.
I am listening to this amplifier with Sennheiser HD6XX and a non oversampling dac (tda1387). I do not have anything to compare it against but it sounds amazing. Thank you xrk971 for the design!
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Very handsome upcycling!
The second old black box is the DAC?
Now you need to upcycle some old headphones with new drivers!
The second old black box is the DAC?
Now you need to upcycle some old headphones with new drivers!
Thank you Andersonix! Yes it is the DAC. Sorry if it is a bit off-topic but here is how it looks inside. I had originally built it with a power supply that has the standard AC transformer, diode bridge, capacitor filtering followed by a linear regulator. I was happy with it until I built this headphone amplifier. Then I started hearing the hum from the transformer at maximum volume. So I tested powering the DAC with batteries as well. Now the background is totally silent even at maximum volume.
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Well done! Doing all this on vero board and a self etched DAC board it looks like. I also love your repurposed enclosures.
Enjoy the great sound from your truly diy setup!
Enjoy the great sound from your truly diy setup!
Super work, DP! Bravo.
Love the repurposed vintage boxes!
Glad the sound is to your liking. My personal opinion is that this circuit is one of the top 3 headphone amps that I have ever heard. So not surprising you like it.
It may not have the power of those big amps, but for a high impedance can like the HD6xx, not too many amps can touch it. Especially for quietness and resolution.
You have Aksa to thank for the circuit. Hugh is a genius with the CFP topology.
Love the repurposed vintage boxes!
Glad the sound is to your liking. My personal opinion is that this circuit is one of the top 3 headphone amps that I have ever heard. So not surprising you like it.
It may not have the power of those big amps, but for a high impedance can like the HD6xx, not too many amps can touch it. Especially for quietness and resolution.
You have Aksa to thank for the circuit. Hugh is a genius with the CFP topology.
Play a little bit with the simulation, by adding a second pnp transistor in darlington configuration the distorsion go down to 0.000449%.
On 120 Ohm Load 🙂
Eheheheh
On 120 Ohm Load 🙂
Eheheheh
Add a PNP and it’s a different amp. It might still sound ok, that is all personal preference. You could add a CCS too instead of R3 and R7.
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X,
You seem to have lost momentum on this amp? I had been using my ESS headphones on my bedroom amp and really enjoying them but upgraded to a pair of Hifiman Anadas for my portable and will need a new portable amp as well. Of course I have at least 3-4 projects ahead but just making sure the pump never looses prime. Just letting you know there is interest.
Bill
You seem to have lost momentum on this amp? I had been using my ESS headphones on my bedroom amp and really enjoying them but upgraded to a pair of Hifiman Anadas for my portable and will need a new portable amp as well. Of course I have at least 3-4 projects ahead but just making sure the pump never looses prime. Just letting you know there is interest.
Bill
Thanks for the show of interest. Actually, I did lose momentum for the lack of interest by people. It’s a lot of work to do these projects and I move on if it doesn’t seem to gather the steam needed. The amp works fine - I ran into issues with the fuel gauge feature. It required reconfiguring all of the resistors to get it to work.
All your work is appreciated even if I don’t build , I always read your posts learn something.
Thanks
Bill
Thanks
Bill
Hi Bill,
Thanks for the vote of support. One can always make the Hakuin in Yarra daugterboard format. Nice desktop headphone / preamp. One of the best sounding there is IMO.
Thanks for the vote of support. One can always make the Hakuin in Yarra daugterboard format. Nice desktop headphone / preamp. One of the best sounding there is IMO.