music, guitars & other obsessions

Projects On Deck

Since it is the start of a new year, I am taking the opportunity to outline the projects that I am currently working on:


All Octal Amp – using the parts and chassis from the 6N8 6P3 kit, I intend to turn this into a dual channel guitar amp, so far I have sim’d a few designs, and the most promising one seem to be based on the Top Boost AC4 from Tubeswell, it will include a tremolo circuit, since I have not done one yet.

Tweed Overdrive Deluxe – I got the design from Hoffman’s forum, and it will give me a chance to try out pentode pre-amp distortion (with the 5867), the chassis and parts were salvaged (ok, I stripped it) from a el-cheapo Audio Space Houston Mini-2. I always like the looks of the Mini-2 more than its sound, anyway, it is way too powerful for my hi-fi, so why not turn it into a stereo/dual channel guitar amp? I incorporated a lot of switching function into the design – each channel can select either the clean or OD pre-amp, then the Phase Inverter can be either Paraphase, Long Tail Pair or Cathodyne, and finally the output tubes will be different for each channel – I plan to have 5881’s on one and 6V6’s on the other. Furthermore, each channel will drive its own 10″ speaker, again, two different ones are available – Celestion and Jensen are being considered. So that’s 2x3x2x2=24 combinations per channel! Probably way too many to be useful, but it will provide a good platform to try out various settings all in one go.

6N2 6P1 Mod – I am thinking to change the circuit to Loftin-White just to see how it sounds, the amp is so simple, so it will be easy to put back if the experiment does not work out.


I have drawn up a few designs over the past few weeks, they will be built after the Chinese New Year when the workers return.

Asbury KO – I took the dimension from Woden Design’s Victory posted on the web and scaled it up slightly to fit the Alpair 12 (which why it is the Asbury).

Fritzmaurice FX10 KO – I used some photos posted on the web and tried my best to guess the dimension for the FX10, the trick was to get the cross-firing and the tilt angles, which I estimated at 17 and 15 degrees respectively, as they say, it is close enough for rock n’ roll.

AX84 Cabinet – I am having another one made to match the one that I already have, so they could be placed in a stereo fashion or used by another amp.


As usual, I am finding the biggest challenge to be in the hardware – the chassis, the faceplate, and the cabinet, like they say, 80% of the work for amp building are not electrical/electronic related, no kidding! That’s why having a small CNC machine that can do metal, wood and plastic milling is so attractive to me, it will save so much time (well not counting the learning curve on CNC itself), so that is another project all by itself.


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