List of best DIY Headphone Amplifiers

Ok that's what I thought....for a reference amp the ideal straight wire with gain, the HP1 seems to be one of the best out there but its not cheap!

The BH stuff is not reference quality by these standards..but they work so well musically and are relatively affordable.

AGDR has come up with a bunch of designs from a better cmoy Altoids tin amp, the OD Booster board, and his ODA and an inverting version of the O2. Great DIY projects.

Good luck on your Crack. let us know how you like it and your build goes.
Alex
 
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Reviews of my SE Class A Pocket amp here:

Headfonics review:
XRK Audio NHB Pocket Amp Review - Headfonics.com

Brooko's review:
XRK Audio NHB Portable Class A | Reviews | Head-Fi.org

Audioprimate's review:
Pocket Class A DIY Headphone Amp by XRK971 – Audio Primate

Sound quality rating is up there among the best amps - and all done with two transistors.

You can build your own here:
xrk971 Pocket Class A Headamp GB

Brooko likes it so much, he bought the free sample I gave him so he could call it truly his own. Here it is paired with his HD-800's:
9936678_l.jpg


I am not saying you have to buy a pre-made one, build the DIY version for under $45. Just have to listen to it to believe.

A more powerful desktop version (110mA bias current) coming soon:
661812d1518358924-xrk971-pocket-class-headamp-gb-dca-v4-png
 
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It seems the freq response and some other images don't show up on the original post anymore. Where can I find them?

That’s odd - they work for me and that thread has been around about a year no one else mentioned they can’t see it. Are you logged in as a DIYA member when viewing ? Visitors don’t always see all images. The images are all on DIYA servers.
 
That’s odd - they work for me and that thread has been around about a year no one else mentioned they can’t see it. Are you logged in as a DIYA member when viewing ? Visitors don’t always see all images. The images are all on DIYA servers.

Here's what I see (when logged in):
 

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I found this amp kit.

Looks very interesting.... Maybe I will try this one.

Dual Class-A II Line Output and Headphone Amplifier

That's a nice amp, and Wayne Kirkwood's similar heritage amp (unity gain current buffer based on THAT1646 driving BD139)`40 in Class A is a fantastic headphone amp. Easy to make too - Gerbers available in this thread. Maybe $10 in parts for one of the best measuring HPA's out there. It's Class A push-pull, zero global feedback, and self auto-DC offset built-in (what's not to like?).

641084d1508438947-esp-hpa-ha-r1-sch-png


643817d1509783306-esp-hpa-that1646-hpa-build-testing-jpg


643819d1509784405-esp-hpa-that1646-hpa-1vrms-50ohms-fft-jpg
 
I was wondering how you got such low thd with what's basically an open loop output buffer.

It might be worth mentionning that this measurement graph is taken with a divider and should be corrected by 20db before being compared to other amps... Some amps are measuring quite a bit better, especially ones done with composite opamps.
 
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I was wondering how you got such low thd with what's basically an open loop output buffer.

It might be worth mentionning that this measurement graph is taken with a divider and should be corrected by 20db before being compared to other amps... Some amps are measuring quite a bit better, especially ones done with composite opamps.

This was only putting out 1vrms or 2.83vpp so I was running without an input attenuator. It was connected to my noisier PC, which adding some baseline grass. My other PC, with a solid state HD has an even cleaner baseline with same Focusrite.
 
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FWIW the Bottlehead Mainline is reputed to sit performance wise between the DNA Stratus and the Dynahi both highly regarded reference level amps

Given the Stratus had upgrade tubes bringing its price up to $3450 and if we use Bottleheads regular promotion price on the Mainline of circa $1000 the Mainline was a third of the Stratus price in the head to head and I believe the Dynahi is more expensive than the Mainline as well.

A reviewer on headfi had all three and had both the Mainline and DNA Stratus at the same time.

Bottlehead Amplifier Discussion / Comparison Thread: Crack, SEX & Mainline | Page 70 | Head-Fi.org

I also have a Mainline its definitely a reference level amp but you do need top tier phones like the hd800 and a quality source to match to get a handle on just how capable it is.
 
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I might add if you use power hungry Planar Magnetic headphones the 6W Nelson Pass ACA ($149 for the full kit & probably close to half that if just purchasing the pcbs and diying an enclosure) can make fantastic pairing but performance can vary depending on the preamp used.

Made a fantastic pairing my Hifiman HE-6. Just goes to show you don't need to spend a fortune to get great performance.

Amp Camp Amp Kit – diyAudio Store
 
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Reading the thread where you posted this graph: "Ok a quick measurement with Focusrite 2i4 and 1.00vrms into 50ohm load, read out with 10:1 voltage divider."

Btw: here are the measurements open loop vs closed loop of Wayne Kirkwood DCAO2: An Improved Dual Class-A Output: The "DCAO2" - Page 4 - Pro Audio Design Forum
As expected, closed loop is needed to achieve very low distortion.

Sorry - I must have forgotten - I’ll take another measurement without it and repost. Give me a few days.