D3ap pentrode Drive 2A3

[colin.hepburn]

Hi All
does anyone have any thoughts on this amp a D3ap pentrode Drive 2A3
i have the schematic if anyone wants a look PM me
http://home.att.net/~abraxasaudio/proje ... 3d3ap.html

[Nick]

Should work well enough. I am rather fond of the d3a. But in this case I would be tempted to use it as a triode with a CCS load, either solid state, or maybe another d3a.

[colin.hepburn]

Thank nick
I’m just trying to Decide on what 2a3 amp as my first build over the winter I have been looking at doing the 6EM7 and perhaps adding a 2a3 on but I want to keep it simple The pentrode drive maybe a bit much for a first build

[Nick]

The only thing to beware with a pentode is that its stable at RF, not a big problem with a d3a I have found, but you need to make sure that grid stoppers are next to the valve pins. That sort of thing.

It should end up very similar to Dave's c3g 2a3, which started life as a sketch by james I believe.

[Andrew]

I agree, D3A makes both a nice triode and a good pentode should be a good driver for 2A3, plenty of headroom either way.

In fact, it should be easy enough to try both and decide which you like best.

cheers,

-- Andrew

[simon]

I haven't tried a D3A yet but I know you chaps have used them quite a bit. How do they compare to C3g in broad terms?

[Andrew]

Bit more of everything, higher mu, higher gm, higher miller, higher anode dissapation and higher cathode current.

I was very impressed with the lack of any colouration at all in Nick's anode follower; they sounded good in the LCR, but not quite enough gain when compared to the E810F.

I suspect its slightly noisier than the C3g, but have no proof.

[Nick]

Its silly, but I haven't done a direct comparison between the two. I should.