D3A
D3A
Are D3A's actually still available? Anybody know?
All these great D3A circuits and circuit ideas - but where to get the tube?
Some one recently pointed out to me the wisdom of using EF86's for small signal pentode work: "they're still in production"...Amen!!!
All these great D3A circuits and circuit ideas - but where to get the tube?
Some one recently pointed out to me the wisdom of using EF86's for small signal pentode work: "they're still in production"...Amen!!!
very cool, thanks, Lars
Question for everyone: for small signal work, including REALLY small signal work (mm or even mc cartridges, playback heads, etc - but not RF stuff), what is the advantage of a D3A over the EF86?
The steilheit of the D3A is 35 mA/V, whereas for the EF86 it is but 1.8 mA/V, so I get that the potential gM of the D3A is almost 20 x the EF86, but that also means the D3A is more like a mosfet than an EF86 LOL...whereas the EF86 is more like a triode sans Miller effect (yes, it's still a pentode for the hair-splitters)...so, if we're going to go to a D3A, why not just cut to the chase and use a small mosfet?
While the D3A has more gain, it also is more susceptible to oscillation, noise, microphonics, clipping and odd harmonics...no?
OH! I think I just figured it out...more or less....my comments re just using a mosfet still hold, I think, but the essential difference between the D3A and the EF86 is CURRENT...20+ mA Ia vs 3 mA Ia. So, if you want a lot of gain AND a lot of current up front, in order to drive the capacitance of a big triode, the D3A gives you that. Hmmmmmm........
Question for everyone: for small signal work, including REALLY small signal work (mm or even mc cartridges, playback heads, etc - but not RF stuff), what is the advantage of a D3A over the EF86?
The steilheit of the D3A is 35 mA/V, whereas for the EF86 it is but 1.8 mA/V, so I get that the potential gM of the D3A is almost 20 x the EF86, but that also means the D3A is more like a mosfet than an EF86 LOL...whereas the EF86 is more like a triode sans Miller effect (yes, it's still a pentode for the hair-splitters)...so, if we're going to go to a D3A, why not just cut to the chase and use a small mosfet?
While the D3A has more gain, it also is more susceptible to oscillation, noise, microphonics, clipping and odd harmonics...no?
OH! I think I just figured it out...more or less....my comments re just using a mosfet still hold, I think, but the essential difference between the D3A and the EF86 is CURRENT...20+ mA Ia vs 3 mA Ia. So, if you want a lot of gain AND a lot of current up front, in order to drive the capacitance of a big triode, the D3A gives you that. Hmmmmmm........
-
- Posts: 64
- Joined: Sun Jun 26, 2005 8:38 pm
- Location: Folkestone, UK
-
- Posts: 64
- Joined: Sun Jun 26, 2005 8:38 pm
- Location: Folkestone, UK
-
- Posts: 64
- Joined: Sun Jun 26, 2005 8:38 pm
- Location: Folkestone, UK
-
- Posts: 10
- Joined: Thu Aug 23, 2012 3:33 am
- Location: New Zealand
D3A
Hi,
A D3A has a mu of 70 and was designed to give good
performance as a pentode or high mu triode.
I use D3As in a SET amp as an input/driver tube and yes they are available.
Another similar pentode which can be used as a high mu (50)
triode is the 7221 or E180F.
I use Mullard NOS E180Fs in my LCR phono stage as input tubes.
Kevin.
A D3A has a mu of 70 and was designed to give good
performance as a pentode or high mu triode.
I use D3As in a SET amp as an input/driver tube and yes they are available.
Another similar pentode which can be used as a high mu (50)
triode is the 7221 or E180F.
I use Mullard NOS E180Fs in my LCR phono stage as input tubes.
Kevin.