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My new Poseidon's Finished, very happy with them

PostPosted: Thu Oct 06, 2011 7:45 pm
by n8zfm
Guys I want to thank everyone on this forum for all the knowledge, general advise to others, and ideas that I used in building these units. I also need to thank Shannon for his design and the PCB I purchased to make these.

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
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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)

Thank you again Shannon for the design.

Dave, N8ZFM

PostPosted: Thu Oct 06, 2011 8:08 pm
by Ty_Bower
Those are some very fine looking amplifiers, and you should be proud of them. Your craftsmanship and attention to detail are top notch. I very much enjoy my Mark III amps with the Poseidon boards, though I won't ever be able to claim they are as fine looking as yours.

There is just something about having plenty of clean, fixed bias, push pull KT88 power on tap that always satisfies. Regardless of the situation and surrounding conditions, these are the amps that get the job done right.

PostPosted: Fri Oct 07, 2011 5:45 am
by WA4SWJ
Good grief! Nice work. Love those dovetails .....

Regards,

PostPosted: Fri Oct 07, 2011 7:31 am
by Shannon Parks
Very nice work, David, and thanks for uploading the pictures for us. Glad you enjoy the end result. [:)

Shannon

PostPosted: Fri Oct 07, 2011 2:10 pm
by Wiesiek Lipowski
n8zfm

As I recall Poly Natalia loudpeakers were meant to be driven by 300B SE kind of amplifiers. I myself own MkIIIs/poseidon, and once tried friend's Natalias with them. Poly Natalias had Audaxes and Morel 33s indeed. The sound was so clean, hard and clinical that I started hating music and quickly got back to my good old PRO9-TLs.
I think MkIII even in triode mode is not an ideal amp for Poly Natalias. However, this is only my humble opinion.

Good luck
Wiesiek

Speakers

PostPosted: Mon Oct 10, 2011 10:33 pm
by n8zfm
Well each of us is entitled to their opinion, and no where more so than art, which music truly is. I love the sound from the Morel's and the Audax's and yes I would describe it as very detailed and I guess you could say clinical, but regardless I love it and they sound better now with the poseidon's, but I am very well aware its a personal preference and at least right now, so far, we all have the right to have different ones - long live that right! You would not be on this board if we did not agree on more than we would disagree on.
Not familair with a PRO9-TL can you point me somewhere where I see the design? Never know I might change my mind.

73 - Dave, N8ZFM

PostPosted: Tue Oct 11, 2011 12:01 am
by Wiesiek Lipowski
You can find some info here:

http://homepage.mac.com/planet10/TLS/do ... TL-Mk2.pdf

The project comes from 1976, some drivers are hard to find these days I'm afraid.

Greetings
Wiesiek

PostPosted: Thu Jan 05, 2012 6:17 pm
by K4ECA
Those are great looking amps Dave, I like the box joints so much that I spent the past Sunday making a box joint sled for my table saw (turned out well).
This site (read it's members) always inspire me.

73 from 4 land!

PostPosted: Thu Jan 05, 2012 7:23 pm
by Thermion
Very nice looking amps indeed. I need to learn some advanced woodworking. I've been using 45 degree miters on my amp bases. Yours look much better.

I love JJ power tubes (KT88s and EL34s), but have been disappointed with the GZ34. I had one fail in a MKIII. The Sovteks seem to be more reliable IMHO.

JT

PostPosted: Thu Jan 05, 2012 9:05 pm
by Geek
That's totally sexay (love)

The wood/finish/box joints are super.

Cheers!