Part Sources:
I got the transformers and the input PCB from Triode Electronics
Tubes are Electro-Harmonix except for the rectifier (JJ)
I designed a simple PCB for the power supply - I departed from the design by adding a step start with a couple relays and resistor, a idea I use all the time on large PA tubes for radio amplifiers and ay be unnecessary here but it adds like 5$ total to the amp.
Not being a metal worker worth a crap I had a company named Protocase make the chassis from my own CAD design, and then had the local Harley shop chrome plate them for me (tube amps are supposed to be chrome plated right?) :)
I made the wood wrap arounds myself.
Most of the parts came from Mouser except the meters I added for a built in bias adjustment I got from China via E-Bay.
I used in the signal path Mundorf Z series caps, I did not spring for the pricy paper/oil/silver ones but these are an upgrade and even if I can't hear a difference they were not that pricy. I make no claims to being able to "hear" caps (unless they are bad or wires).
My unique changes to Shannon's design consist of:
Step start curcuit to prevent heater shock to the tubes.
Bias meter to be able to check and adjust the bias, this was done with a tiny SPDT center off switch and in order to make this easy I put two panel mount 10 turn pots on top of the chassi, not that I plan on adjusting that often but it makes it easier and I don't risk breaking a tube with the amp on its side when I do need to adjust.
I added a Triode/UL slide switch, altough I have yet to try Triode mode, just seemed neat to add.
Impression so far - these sound very good, nice warm sound. They are replacing a much loved 25 yr old Carver M500t on the front channels. I had 7 chassis made as besides music its a home theater (7.1) so plan on running these on all 7 channels and then continuing to use SS for the Sub. I have now been playing them for about 2 weeks but can notice no difference in sound from the start, altough as expected the tube settled in after about 50 hours and I made a very minor bias adjustment. I have played both classical and 60's, 70's rock and the mirange detail is very good, nice sweet highs and suprisingly good bass, I only turn on the sub for movies and TV.
Speakers are the Poly Natalia's designed by Dick Olsher using Audax woofers and midrange and a Morel MDT33 Tweeter. These were also built by me a few years ago.
I am not sure how to attach a picture so hope these come thru if not they are on my web server
![Image](http://www.n8zfm.com/MKIII_Poseidon_Amp/Left_Side.jpg)
![Image](http://www.n8zfm.com/MKIII_Poseidon_Amp/Right_Side.jpg)
![Image](http://www.n8zfm.com/MKIII_Poseidon_Amp/Top.jpg)
![Image](http://www.n8zfm.com/MKIII_Poseidon_Amp/Front.jpg)
![Image](http://www.n8zfm.com/MKIII_Poseidon_Amp/Back.jpg)
http://www.n8zfm.com/MKIII_Poseidon_Amp/Left_Side.jpg
http://www.n8zfm.com/MKIII_Poseidon_Amp/Right_Side.jpg
http://www.n8zfm.com/MKIII_Poseidon_Amp/Top.jpg
http://www.n8zfm.com/MKIII_Poseidon_Amp/Front.jpg
http://www.n8zfm.com/MKIII_Poseidon_Amp/Back.jpg
One note about these pics, the chrome looks dusty and its not (really) it also seems to create some strange reflections, these do look better without a flash. My name is David Trainor - N8ZFM is my radio callsign, and since I sorta made some mods to Shannon's design I put my name on the front of the wood, yeah its a bit egotistic but so what?
![LOL (lol)](./images/smilies/lol.png)
Thank you again Shannon for the design.
Dave, N8ZFM