I recently made an interstage for a 300b to drive a 211. Must be suitable for a 2A3 too i guess.
I'm no expert but if I'm right, it dépends how you "optimized" your interstage.
According to what I read, we can have different reference loads from the max plate to cathode voltage (300V), max current (60mA), and max plate dissipation (15 watts). At 300v, 40mA: 5.3k...300v, 50mA: 4k...250v, 60mA: 2.5k.
If I was "conservative", I'd stay around 10W dissipation but for what I know, 211 needs to be kicked in the ...to perform well, that what I asked for suggestions.
It seems Lundahl LL1671 could be a possible choice for 2A3 or similar Rp tubes.
Unfortunately, I have good ones from Electra-Print but limited to 30 mA and better suited for something with higher Rp.🙁
Unfortunately, I have good ones from Electra-Print but limited to 30 mA and better suited for something with higher Rp.🙁
An interstage is not an output transformer so the loadline is different because usually there is no loadresistor (and if it is high).
The interstage i made was designed for a tube with an Ri 600-900Ω, 40-80mA.
It can deliver 85Vrms even at 10Hz and frequency response is at least 10Hz -500kHz
More stable / better drive force for your output tube. You can also drive a tube in A2 (positive grid, for more power 🙂 )
Ohh, and the sound is rock solid.
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alternative
Trinitus, you can also use a "powerdrive" like the one in Tubelab SE . I built this amp with 45 tubes few years ago and the results are quite good. I could take that way instead of a IT but this is not what I prefer.
Trinitus, you can also use a "powerdrive" like the one in Tubelab SE . I built this amp with 45 tubes few years ago and the results are quite good. I could take that way instead of a IT but this is not what I prefer.
Hi 211 fan,
I used LL1677 with 300b as driver for my 211 amp with good results. The Lundahl IT is performing very well. Unfortunately not much A2.
If you want to get the extra watt from A2, you'll have to go for cathode follower from 6hv5 or source follower(FET). Trick is that 6HV5 can run at the same voltage as the 211!!! Using A2 you can get more than 30watt from your 211 power tube.
Please check out the new 211 tube at Thomas Mayer blog.
Best regards
Karsten
I used LL1677 with 300b as driver for my 211 amp with good results. The Lundahl IT is performing very well. Unfortunately not much A2.
If you want to get the extra watt from A2, you'll have to go for cathode follower from 6hv5 or source follower(FET). Trick is that 6HV5 can run at the same voltage as the 211!!! Using A2 you can get more than 30watt from your 211 power tube.
Please check out the new 211 tube at Thomas Mayer blog.
Best regards
Karsten
As I said, I'm not an expert and must admit they're all in the same ballpark in my mind . At the difference an IT provides signal ground isolation from stage to stage and can transform signal levels and signal impédances. In my case it must be 1:1 and as we know, has to "feed" a 211.
2A3 Ri is 800 ohm and can "eat" up to 60 mA. I imagine yours could do the job.
However, I own some Electra-Print and Lundahl transformers and can expect a bit the results and prices 😀.
Anyway, I'll send you a PM...
Ouf! That 6HV5 can run at very high voltage! I'd have to change my PWR transformer and use a plate choke instead of IT. But this is an interesting way.
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