Help on single ended 211 question

[tonescout]

A very impulsive question 🙂from a layman.

I have a 211 single ended amplifier with a very simple transformer coupled signal circuit as attached that I am rebuilding with replacement capacitors, as it's 30 years old etc.

I also have a small valve output DAC and I have just found a fabulous sounding valve: Sylvania GB5670 that I am using in the DAC output stage.

The thought occurred to me that I might replace the 6c45 driver valve with a 5670 running both triodes in parallel instead (1 per channel). I can easily change the Plate voltage as it comes from a 500V supply taken down with a 10K series resistor.

Is this a crazy silly idea for a 211 driver valve or is it something to genuinely think about?

Appreciate your input/thoughts

Thanks!

Rich

 

[kmtang]

Hello Tonescout,

The 211 tube isn't difficult to drive. To my understanding, the 5670 has plate resistance of approx 6.4K per section. I believe this is just good to match with the LL1660 interstage transformer. Mis-match of the source impedance would cause much narrow bandwidth or high oscillation at high frequency end. I think it is worth to try the 5670 tube and monitor the frequency response.

Johnny

 

[euro21]

5670 gain about 25.
6C45P has at least -averaged- double gain.

 

[tonescout]

What confuses me about the 6c45 is the multiple cathodes , however it is a single triode at 52 gain.
The 5670 is 35 gain in class A, and I would run both sides of the triode in parallel for 1 channel so I assume that the gain then increases somewhat.

 

[waltube]

One of the best is E280F in triode
Great tube!!!
High mu, low Rp
Walter

 

[vinylkid58]

so I assume that the gain then increases somewhat.

Don't think so. Rp would be 1/2 with the triodes paralleled thou.

jeff

 

[vinylkid58]

What confuses me about the 6c45 is the multiple cathodes

You mean multiple cathode connections.

jeff