• WARNING: Tube/Valve amplifiers use potentially LETHAL HIGH VOLTAGES.
    Building, troubleshooting and testing of these amplifiers should only be
    performed by someone who is thoroughly familiar with
    the safety precautions around high voltages.

Aegis DIY Tube Headphone Amplifier

Member
Joined 2019
Paid Member
Hello,

I am releasing a DIY tube amplifier project, the first complete DIY project I've released on this forum. The amplifier is called Aegis.

I started my DIY journey on the headphone forum Head-Fi. I have something of a tube DIY blog there where I catalog all of my ongoing projects. For a short period of time, I was building and selling my designs as a hobby business, but quickly realized I didn't have the time for it working a full time job. I thought I'd work on a DIY amplifier that forum members could build for themselves without my involvement. I've been working on it for the past year or so.

This is a headphone enthusiast's tube amplifier. I say that as I'm sure some will balk at the cost of parts, which is roughly $2,000 USD. Given what some people are willing to pay for commercial tube headphone amplifiers, which are creeping toward five figure prices, it's relatively affordable. I tried to come up with a design that 1) is easy to build, even for a novice DIYer, 2) uses easy to acquire vacuum tubes, 3) is simple and robust with low likelihood of parts failure and easy to troubleshoot, 4) uses a circuit that is not readily available on the commercial market, and 5) sounds good! I do not typically build budget-oriented designs for myself, and I did not do so here. I like to build amplifiers that look like professionally made products. Please abstain from telling me that it is too expensive, a waste of money, etc. You do not have to build it.

I've included download links to the BOM, chassis CAD files, and an exhaustive project document that includes an explanation of the circuit, schematics, recommended equipment, information on acquiring parts, step-by-step instructions with photos, testing procedures, and some basic measurements. Please note the instructions are written for a new DIYer, not one with experience, so they are very detailed. The gerber files to order the PCBs are attached to this post.

Measurements are in the last section of the build document.

You can find some subjective impressions of the amplifier here:

https://www.head-fi.org/threads/aegis-diy-tube-headphone-amplifier.965530/post-17224730
https://www.head-fi.org/threads/zmf-caldera-new-planar-magnetic-from-zmf.964836/post-17553801

Please let me know if you come across any typos or anything seems out of place and I will try to address it.

Link to build document PDF: https://drive.google.com/file/d/1C2NSRh8DkC1Blr2GMVC_83XAdM0IUFZA/view?usp=sharing
Link to the Excel BOM: https://docs.google.com/spreadsheet...ouid=113213015624875847507&rtpof=true&sd=true
Link to zipped chassis CAD files: https://drive.google.com/file/d/1GXCq11-S97FtTey2lVpv6CgkBul4Uryb/view?usp=sharing

PXL_20230310_231254258.jpg PXL_20230310_233107674.jpg PXL_20230310_233336192.NIGHT.jpg
 

Attachments

  • Aegis Alps Pot PCB.zip
    5.7 KB · Views: 328
  • Aegis ELMA Switch PCB Revised.zip
    9.5 KB · Views: 236
  • Aegis Amplifier PCB v1.1.zip
    24.4 KB · Views: 69
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ra7

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Joined 2009
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Simply amazing! The write-up is insanely detailed and superbly done. Thank you! An inspiration!

Nice headphone amp too. Question: what is the motivation behind chokes and transformers as opposed to CCS? Just curious if you heard differences you liked.
 
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Member
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This is being missed because most people don’t search for in the tube section. I missed it at first, wonder if it could be cross posted into headphone amp section. Ck out the documentation on this project it surpasses any I have read.
Bill

I can run it by the moderators and see where they think is the more appropriate place. But my feeling was tubes trumps headphone amp.
 
Member
Joined 2019
Paid Member
Simply amazing! The write-up is insanely detailed and superbly done. Thank you! An inspiration!

Nice headphone amp too. Question: what is the motivation behind chokes and transformers as opposed to CCS? Just curious if you heard differences you liked.

Since the output stage is a cathode follower, all of the voltage gain of the amplifier is generated by the input stage. The 810H choke load allows the 6SL7 AC signal to swing above the B+ voltage while still keeping distortion relatively low.
 
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Since the printed circuit board needs to be custom made and a minimum of 5 have to be ordered we will have to make a group buy if enough, or if interest is low I will just order 5 and sell off the ones I don't use. I have the transformers & Case & Elma switch paid for and on order I guess i am committed.
Bill
 
Member
Joined 2019
Paid Member
I added a link to the zipped chassis CAD files if someone wants to pursue a different chassis maker outside the USA. Note that the files are set up for Landfall, who uses a 0.125" aluminum chassis. The way the chassis fits together, 0.125" is trimmed from all four panels of the top and bottom plates, and the front and back sides of the two side panels. The total chassis dimensions are 13.5" x 13.5" x 3.25", but because of the trim, you'll find the top and bottom plates are 13.25" x 13.25 and the side panels are 13.25" long.
 
Since the printed circuit board needs to be custom made and a minimum of 5 have to be ordered we will have to make a group buy if enough, or if interest is low I will just order 5 and sell off the ones I don't use. I have the transformers & Case & Elma switch paid for and on order I guess i am committed.
Bill
Hi Bill, I'd be interested in one if you proceed. The people on HeadFi likely would be as well as the forum doesn't permit group buys any longer (there's been some history of issues).