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?
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.
I don't know how much current that I can pass through a 76, I don't have any.
tubelab.com said:
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
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.
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.
I'm thinking of LED or CCS on cathode as possible upgrades.
tubelab.com said:
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
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