Just discovered this thread, almost a year later...
Steph - I really like your design, and contemplating using it as a starting point for a headphone amp (i.e. have headphone jack instead of speaker taps).
I am wondering how quiet is the noise floor, since some of my headphones are very sensitive.
Also, knowing that even 0.5W would be overkill for my use case - I wonder if I could use smaller OPTs.
Thoughts?
Steph - I really like your design, and contemplating using it as a starting point for a headphone amp (i.e. have headphone jack instead of speaker taps).
I am wondering how quiet is the noise floor, since some of my headphones are very sensitive.
Also, knowing that even 0.5W would be overkill for my use case - I wonder if I could use smaller OPTs.
Thoughts?
Instead of using a 6BM8, I used a 13DR7 for my headphone amp, a dual dissimilar triode used for vertical oscillator/amplifier service (they cost me $1 apiece, a deciding factor). I used a smallish transformer from Transcendar that looked like it was wound for headphone service - probably unobtainium now, as they don't seem to be accepting orders from retail customers any more. Thread is here:
https://www.diyaudio.com/community/threads/se-vt-headphone-amplifier.339328/
The Transcendar transformer called out in that thread would be a possibility if still available. Maybe you could also try a Hannond 125BSE or 125CSE - probably not up to the quality of the Transcendar XFMR, but it would still make some noise. The other option would be to go parafeed and use a small power toroid as output transformer, or one of the line transformers from Edcor.
https://www.diyaudio.com/community/threads/se-vt-headphone-amplifier.339328/
The Transcendar transformer called out in that thread would be a possibility if still available. Maybe you could also try a Hannond 125BSE or 125CSE - probably not up to the quality of the Transcendar XFMR, but it would still make some noise. The other option would be to go parafeed and use a small power toroid as output transformer, or one of the line transformers from Edcor.
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I am looking to build a small simple desktop tube amp for work. This looks like a good candidate. Nearfield use at low volume so power requirements are very low.
Questions.
Any reason to consider the 15w OPT? I think for my case no but I could not find any follow up testing to see what impact the larger OPT had on performance.
I am going to build it as a mono to drive a single small fullrange speaker. Anything to consider when scaling down the power supply for a single channel?
Questions.
Any reason to consider the 15w OPT? I think for my case no but I could not find any follow up testing to see what impact the larger OPT had on performance.
I am going to build it as a mono to drive a single small fullrange speaker. Anything to consider when scaling down the power supply for a single channel?
A larger OPT will usually improve low frequency response when working at a lower power from the maximum specified by the manufacturer. Especially for circuits without global negative feedback. You will also have less distortion, especially at low frequency.
For the small price difference, if I was doing this again I would for sure for my use go with the GXSE15 instead of the GSXE10. That said I still use mine as built daily as a background music amp in my workshop. And the GXSE10 makes for a smaller footprint.
I use mine on my desk. The near field stereo is awesome. Go ahead with the stereo version, you will not regret ir.