DH SET--OK I get it now

[mesherm]

http://home.earthlink.net/~mikesherman/ ... 3amp-1.jpg

I just finished building my 2A3 SE amp.
I used an Aikido stereo PCB as a front end. I have been collecting parts since last year. The PT was a custom wound toroid courtesy of Boris at Vista Audio. OTs are stock James. It uses fixed bias so no cathode resistors or bypass caps. AC filament power. Choke input power supply.

Sorry about the pic...I will take some better ones later. I am doing some listening tests right now. My initial impressions are that it it very crisp and detailed. Great bass without being boomy. Every small audio detail comes through like the delicate sounds in the backround at the beginning of the Doobie Bros "Black Water". I heard all those harp/zither strings being strummed in the backround and those delicate chimes.

I can see now why people get excited over these big power triode SE amps. I know I am going to relisten to a lot of my CDs and vinyl now.

[hasafraker]

that's gorgeous man if it sounds half as nice as it looks I'm sure your going to have a real hard time wiping the grin off your face Yellow_Light_Colorz_PDT_01

can't wait to see some cleaner pics!

[SDS-PAGE]

Now, that's really nice. I like how all your irons are round. Since you had a taste of DH SET, you ought to build a 300B amp next. Good work!

[TomMcNally]

Looking good Mike !

Does your PT have dual 2.5 volt windings and 5 volt and 6.3 volt ?

By the way ... the intro of Black Water sounds awesome when it goes through all of the processing at the radio station I work at on the weekend. It brings it up to 100% and it really sparkles. We have it adjusted agressively, but not obnoxiously.

... tom

[crispycircuit]

Great job! It's such a pleasure when everything comes together like this. The hrs invested in planning, work, and cost is impressive and demonstrate your desire to follow through..... Some projects seem to get caught in the "stall" position for yrs... Could you stop over and kick my ass??

[mesherm]

OK, here are better pictures.
http://home.earthlink.net/~mikesherman/ ... -front.jpg
http://home.earthlink.net/~mikesherman/ ... inside.jpg
http://home.earthlink.net/~mikesherman/ ... a3-top.jpg
http://home.earthlink.net/~mikesherman/ ... 3-rear.jpg

Tom, the PT I had made with 320-0-320, two 2.5 volt CT, 6.3 volt CT, and a 70 volt bias winding. the 320 winding is rated for 400ma and the 2.5 volt are 6 amps each (In case I wanted to use parallel 2A3s). The transformer is way over designed and bearly even gets warm to the touch after 2 or 3 hours. The amp has no hum that I can hear even with my ear to the speaker so I don't see why people need to run DC filament voltage.
The meter is a 1 volt dc meter I was lucky enough to pick up on ebay so I just used 10 ohm cathode resistors on the filament CTs to ground to check current flow. The switch on the front switches between them.
The Aikido is all DC coupled so there is only one coupling cap in the signal path. That and not having to use a cathode bypass cap I think improves the signal response. I will be doing extended listening with this puppy believe me.