Ok, there will be a few people out there that will remember last year when I posted a thread about building the Aegis Headphone tube amp. It was my first DIY build and, it turned out really well. Sounded fantastic and was fun to build. So good in fact, I sold my Auris Nirvana which is a £6k headphone amp new (original wood version).
Anyway, after adding some really good NOS tubes it became obvious this was an amp that was never going to be sold. So, I started thinking about designing a new chassis from scratch, upgrade wiring to the best Neotech solid core copper I could get, upgrade caps, use Jupiter 600v instead of 400v copper foil caps and fit some hi end Neotech interconnect cable from RCA plus to the analogue volume pot.
The chassis design had a few must haves. 1) move the impedance dial from the back to the front. 2) the top panel could not have any visible screws to detract from its looks 3) must look commercially built and feel premium. 4) make it easier to place IsoAcostic Orea feet in the correct position.
This is how the amp looked before the make over. I still have this chassis @Mark63 so it may still live on
The new chassis would have a high gloss finish top and bottom. Its centre core would be leather bound and the base would have three cutout, inserts for the Orea feet to sit in. It also had to be a little wider, 400mm width as I needed extra space to allow me to move stuff around internally so a metal rod could extend from the back to the front panel. This would become the dial for the impedance switch.
All I needed to do is start it. I’d been mulling this over for months. A fellow Head Fi member heard about this and also wanted one of these amps but wasn’t in a position to build it. So, after a bit of encouragement I started.
The amp has been completed but I’ll try to post stuff in order. I would have started posting this while I built it, but to be honest, I didn’t know whether my creative skills were pushing my DIY skills too far😂
Future posts won’t be so wordy now I have explained stuff
Materials for the chassis would be MDF for the top and sides. A large panel of aluminium under the top panel. This is where the sockets would attach to and all the screws needed to fix them and the PCB board would attach to that panel.
I used screw inserts into the MDF so the chassis could be built, dismantled and rebuilt as many times as I wanted with degrading the fixings.
I used screw inserts and what are called modesty blocks… never knew they were called that until I had to buy them. The chassis had to be able to be disassembled not just for the build but also if repairs are needed in the future.
Next stage was strengthening the front fascia. Even 2.5mm of aluminium flexes when pushing in an XLR4 plug. Two 3/8 bars fixed to the front plate with a special glue. Then marking up, drilling the holes etc
Not sure how many posts I can make without reply. So this may come to an end. Next up was fitting the leather to the core of the chassis and the inset rear panel
Once I was happy with the finish of the primer, it was onto paint. After a coat of paint, a sequence of lacquering started. Every 30 minutes a new layer applied until it had 6 coats. Touch dry between each coat. The aluminium was also pained gloss black and lacquered as well.
Ok, internals now. Fitting the board to the aluminium panel was a little fiddly. The board is designed for a smaller spacing of the tube sockets so instead of using a socket that solders to the board, I used sockets that would take a wire.
Next was making and fitting a bracket for the impedance dial rod. This is to ensure the dial is 90 degrees to the face. The steel rod flexes and is attached to a flexible coupling which allowed it to weave between the components.
View of the completed main board with tube chokes fitted and wiring to the XLR4 and 6.35 sockets. Also, the triple shielded Neotech interconnect cables connecting the RCA sockets to the volume pot.
So, all that’s left is the finished amp shots complete with logo badges etc. Turned out to be a lot more involved but happy with the results…. It was great to be able to just sit back and enjoy it
Thanks… it was something that I had in my mind for ages and I was relieved, happy with the results. It presented a lot of problems to solve at times but as it’s intended to be an amp that I’ll keep forever, it had to look and sound right even if it meant more work!
I’m going to do one tweak to the power supply so that it’s more aimed at taking the 274b rectifier tube. That should only be a 5 minute job though. The sound quality has certainly improved over the original one as well which is an added bonus
I may have missed this in your write up but how long did it take and which headphones will you use? And one more thing why don’t headphone amplifiers have a balance knob?
The chassis is what ate up all the time. I created scaled drawings which helped a lot and I was able to complete the chassis in just over a month. Waiting for paints to dry etc added a lot of time at the end and, I was actually building two of these at once so if I was building just one it probably would have reduced the time significantly.
Not sure why a balance dial aren’t used to be honest. When testing you check that both left and right are equally balanced.
The electrical work didn’t take that long to be honest. Possibly 2 days but I had build one before so I was comfortable with what I was doing etc.
I use the Meze Elites (low impedance setting) and a pair of limited edition ZMF Atrium Closed. I use the Auralic VEGA G.2.2 as a source and a preamp for the Rega P8.
Below is a photo of the two amps together with the VEGA. The second one is now with its owner.
Thank you for your comprehensive reply. Regarding the balance knob, I was thinking that some people may have uneven hearing and that type of control may help.
Its just I’ve never seen one.
I don’t think so, I use an Icon Audio valve headphone amplifier which gets its input from my Naim SN3 amplifier, I’ve tried the balance control on the SN3 it has no effect on the headphone amp.
