Can I use a 01A in a headphone amp?

[arnoldc]

Hi tubelab, was this headphone amp a single 01A? Did you use a driver? Another 01A? If different, how did it influence the sound of the 01A according to your customer. Did he feel he's still getting unadulterated 01A sound?

 

[Tubelab_com]

This amp was made by modifying a TubelabSE board. The driver is a 5842. I don't know what kind of sound we finally settled on, but he really liked it. When I told him that the 5842 could be replaced with a WE 417, he said that this was a good choice. No other driver tubes were tried.

I don't know how much current that I can pass through a 76, I don't have any.

 

[Rocky]

The driver is a 5842.

Ah, I thought you were talking about a single stage.. I've seen transformer loaded 5842 in single tube headphone amps. But that's an IDHT

 

[Tubelab_com]

I have seen a single 5842 put out 500 milliwatts. It has enough gain for a single tube amp. The 01A has a low gain. You can't use it for a single tube amp without a step up transformer for voltage gain. The Rp is listed at 10K ohms. That is at the specified 3 mA. I believe that the Rp is a bit lower at higher current.

 

[arnoldc]

Yep, I use a single 5842 (per ch) for my headphone amp. 200V plate, 2V bias, 20mA, 5K:8,32,300 custom opt. Sounds very nice!

I'm thinking of LED or CCS on cathode as possible upgrades.

 

[sbelyo]

5K:8,32,300 custom opt. Sounds very nice!

How much did that run?

 

[arnoldc]

Around $50 for the set- 1 x power transformer and 2 x output transformer.

 

[Rocky]

I have seen a single 5842 put out 500 milliwatts. It has enough gain for a single tube amp. The 01A has a low gain. You can't use it for a single tube amp without a step up transformer for voltage gain. The Rp is listed at 10K ohms. That is at the specified 3 mA. I believe that the Rp is a bit lower at higher current.

I had problems with gain in designing my latest amp, 8.25x*3x, and I "solved" it with TVCs. Wired as stepups (switchable) they provide 4x gain, but also presents a more difficult load to the source as a result.. however, this is only at the very highest volume settings wich I use rarely, at normal levels it steps down instead. I haven't had the chance to get too aquainted with it yet, but my guess is it will be a bit thinner sounding with weak sources at the highest volume settings, potentially also loose HF to parasitic capacitances in the driver tube if driving currents are low..

Edit: typos