2A3 SE and Edcorp tranny

[ivegotmono]

I've got a couple of new Edcorp SE transformers 5K ohm.
http://www.edcorusa.com/classx/tube_...xse15-8-5K.htm

I want to build a simple 2A3 SE amp so my question is can I use these transformers??
I would appreciate any help with locating a schematic etc also.
Thanks
Steve

[arnoldc]

Do you want to achieve the most output power? With 5K on a 2A3, you will get less distortion at less power.

If I have that transformer, I'd make -

a) 45 amp
b) 300B
c) 807 with UL tap

[tomtt]

http://images.google.com/images?q=2a...0&sa=N&ndsp=20

[Fuling]

Perhaps a different OP with higher voltage and lower current would suit the higher impedance better?
Something like 300V 50mA instead of the typical 250V 60mA for 2A3.

[kmtang]

Hi Steve,

It would be a waste of the 2A3 with Edcopr OPT. 2A3 is a very good sounding tube that it is worth to match with good quality OPT.

If you want to keep the cost down, get the Hammond 1627SE, or James 2.5K OPT.

My friends and I have good experiences with Hammond and James.


Johnny

[tubelab.com]

I agree that the 2A3 can be a good sounding tube, and is often used in expensive amplifiers with expensive transformers. That does not mean that it should not be used in a budget amplifier. You can get Shuguang 2A3's for under $30 each.

The Edcor XSE15-8-5K is a nice sounding transformer and at the 2 watt level it will compare with many of the big boys especially if your speakers are limited to operation above 60 or 70 Hz. For $20 each it is the OPT deal of the moment. Add the $40 Allied 6K56VG power transformer and you can have a relatively good amp for a good price.

I have used these transformers with 2A3's although I am not a 2A3 fan. I prefer the Shuguang 300B. A 5K transformer will work on either tube with slightly reduced power output, but reduced distortion. As mentioned before, run the tube up near its maximum voltage rating at a lower than normal current to take advantage of the 5K load.

I am partial to my amplifier design, but it may be too complex for an inexperienced builder:

http://www.tubelab.com/TubelabSE.htm

It is possible to use the Simple SE circuit with a DHT, but you may need a DC filament supply for the 2A3. I do not yet have the entire schematic on my site, but it will be there in the next few weeks. The PC board schematic can be found here:

http://www.tubelab.com/SimpleSE_schematic.htm

There are dozens of 2A3 schematics on the web. Google around, and find something that you feel is within your abilities.

[alexmoose]

What voltage can a 2a3 safely operate at? the datasheet claims 300v, but that seems a little low for the deisgns i've seen it in

[Geek]

Short answer from experience, most likely yes.

I have heard this transformer up to 5.5 watts with a trioded EL36 (which has a very 2A3 sound) and you can easily get 24 - 19.5KHz with zero NFB at that level. Toss in 3dB NFB for full 20 - 21KHz.

Same great sound from a "little 2A3" (the 45) with extended response.

I've used bias up to 60mA with this transformer with no loss in performance.

I say most likely, because I have yet to hear a genuine 2A3 with it.

[tubelab.com]

I have used this transformer with at least a dozen different tubes, including twin plate RCA 2A3's and Shuguang 2A3's. I have never been a 2A3 fan, but they sound very good with these transformers. The frequencies above 200 Hz have as much if not more life to them as transformers costing much more. In the 20 to 80 Hz region this transformer will saturate at powers above 5 watts. This is not a problem at 2A3 power levels.

I run 45's and 2A3's at 325 volts this is way over the line for a 45 and a little over the line for 2A3's. I have not had any issues yet, but YMMV.

[ivegotmono]

Thanks to all for the comments and reccomendations.
Tubelab, I'm leaning towards your simple se board since this is really sort of and experiment for me. I'll email you re this.
I would appreciate comments from all on this schematic also . (of course I would like to use my Edcorps txs since they seem like a pretty good fit. (I know theyre not ideal) I'm really trying to get a feel for the sound of a low power SE amp without spending a ton of money.


http://www.angela.com/catalog/how-to/SE.2A3.html


Steve