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THD+N 30th November 2010 07:30 PM

Another 2A3 build
3 Attachment(s)
Here are a few pix of my Stereo 2A3 amp. The small foot print, is very heavy, about 50lbs, it is like picking up Lead or Gold, but in this case Iron.

Iron is from Edcor. 6SL7's and 5V4 are NOS US tubes. 2A3B's are Shuguang single plates.

vinylkid58 30th November 2010 07:49 PM

I like your work "under the hood", and the compact footprint.:up:


Mr_Zenith 30th November 2010 08:39 PM

Oh yeah... Excellent work! I love it when a plan comes together. Could you post a copy of the schematic?

jonboy 30th November 2010 09:07 PM

What make are the transformers?

tim614 30th November 2010 09:09 PM


levelfive 30th November 2010 10:31 PM


Point-to-point wiring, buss grounding, tube rectification, mmm... :lickface:

What about a schematic?

tinitus 30th November 2010 11:27 PM


Originally Posted by THD+N (
Iron is from Edcor.

and nicely repainted ;)

there's a lot of good knowledge in those pictures

THD+N 30th November 2010 11:41 PM

I do not have a schematic drawn, but will draw one up and post in the next day or so.

Here are the Edcor model numbers used:
Output transformers are - CXSE25-4-2.5K
Power transformer is - XPWR118-120

For the money, the Edcor output transformers are definitely the "best buy". They have great low end extension and good high frequency response. My measured frequency response (-3dB points) is 7Hz~22.5kHz.

There was a strange low frequency anomaly (+ 0.5dB bump) between 5Hz and 20Hz, so I formed a low frequency cut-off with an input cap that brought my frequency response up smoothly starting around 7Hz.

I'll post a FR graph (with and without input cap) for comparison for those who are interested.

Ty_Bower 1st December 2010 12:45 AM

Nice chassis. What was its previous occupation?

Matt BH 1st December 2010 12:50 AM


How did you get the crackle looking paint?

Cheers Matt.

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