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Looking for tube for application

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I am searching for a tube to use in a particular application, and would like some suggestions.

I am working on a headphone amp that uses a single tube, single ended, transformer coupled to the headphones. So far I have been working with a 6N6p with both sides in parallel. This works pretty well -- plenty of power and decent sound (warm and syrupy), but I'd like to try some other options, perhaps something with a little more gain. The 6C45 looks promising, as does a parallel 7119, but I'd also like to see if anyone has any other suggestions.

Also, I have found that unbypassed resistor biasing seems to sound better to me than LED or bypassed resistor biasing so far, but this does steal a bunch of gain. So, biasing suggestions also welcome.
 
pmillett said:
You could also try triode-connected video amp pentodes (12HG7, etc.). Look out for the miller capacitance, though, on any of these.

I had not thought pentodes at all. Looks interesting.

Geek said:
How about this little parafeed project?


Alain Dupont said:
There are 2 excellent articles from John Broskie:


phn said:

Thanks for the suggestions. I should be clearer. I have the output transformers (James) and have the circuit working. I am just looking for some different tubes to try to explore the topology.

I have taken to building little circuit boards that have the tube, and the associated caps/resistors/LEDs/etc. on board and a couple of terminal blocks so I just pop them in and out of the circuit to explore different options.

So, I am just looking for other tubes to try.

-d
 
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I use 5842 (417A) in a white cathode follower to drive my headphones, I think that one per channel into your 5K transformer would probably rock.

I actually have a fairly cheesy circuit on my site that could be adapted to work in your application. check under the project pages, you want the pre-amp section.

Note there are reasonable models available for the 417A so you can simulate this in your favorite flavor of spice.. :D
 
dsavitsk said:
Transformers are James 6115HS. 5K:8 (phones are 32R and I have a 32R resistor in parallel with the phones, so 10K:16), 70mA, 10W.


Using the OPTs at 10K will work, but be aware that the primary inductance wont really support low bass in tubes with Rp over probably 2Kohms.

FYI - the impedances don't necessarily have to match though you should watch what happens to the AC loadline when you change the reflected load. You could run your 32R headphones off the 8 ohm tap directly with no parallel R. Try it and see what you think.

The 417A and 6c45pi suggestions are good ones. Or you could go two stage with something like a 6EM7 which has two different triodes in one envelope.
 
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