But speakers are closer to 8 Ohm on average (Probably even lower) . That leaves me with a reflected load of say 1250 since the winding ratio is 12.5:1
What would be a tube that would be suitable? Since 2a3 needs around 2,5k. 2a3 *2 would be too much right? For a 3Watt output transformer.
Any creative ideas to make this OT suitable for the usual suspects?
What would be a tube that would be suitable? Since 2a3 needs around 2,5k. 2a3 *2 would be too much right? For a 3Watt output transformer.
Any creative ideas to make this OT suitable for the usual suspects?
While not quite answering your question, some years ago I built a 6C45P Spud amp with a 5k primary parafeed nickel OPT from ElectraPrint. 1.5W wasn’t quite enough for my application as a power amp. But the same parts with a TVC on the input made a wonderful preamp/headphone amp. TVC/CCS loaded 20mA 6C45P/parafeed OPT 5K:16 ohms. ~17:1 step down. The parafeed cap size and type can be varied to taste.
2A3 has a plate resistance of 800 ohms, a 6AS7 has a plate resistance of 280 ohms, it might be worth doing a load line. Link from the past https://www.diyaudio.com/community/threads/6as7-set-amp-discussion-from-photo-gallery.252276/
For 3 watts into a SE amp with a 1250 ohm anode load you will need a bias current of about 70mA so I would expect a low B+ voltage and a tube with a low anode resistance. 6S19P is very cheap but will fall a bit short.
For 3 watts into a SE amp with a 1250 ohm anode load you will need a bias current of about 70mA so I would expect a low B+ voltage and a tube with a low anode resistance. 6S19P is very cheap but will fall a bit short.
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For example trioded E55L output impedance is 600R.
If you use it as parafeed (spud) amp, halving the load (speaker) impedance the power will increase a little, the THD doubling and the HF behaviour degrading.
If you use it as parafeed (spud) amp, halving the load (speaker) impedance the power will increase a little, the THD doubling and the HF behaviour degrading.
Hi euro21
I do like to see your spice simulations, would it be possible for you to include the *.asm file as I like to have a fiddle.
Keep well
kwk
Bas Horneman
Like you I have quite a few 6S19P tubes lying around, I will be very interested to hear how they work out.
Like you I have quite a few 6S19P tubes lying around, I will be very interested to hear how they work out.
Hi Bas,
If you don't have the audio choke, you could consider a power SRPP, that would match quite well with this OPT with 1k2 at the primary side.
Merlin wrote this article https://www.valvewizard.co.uk/SRPP_Blencowe.pdf Second last page has the formula for the optimized unbypassed SRPP. I just plugged in the values for a triode strapped EL84, and it could work.
Erik
If you don't have the audio choke, you could consider a power SRPP, that would match quite well with this OPT with 1k2 at the primary side.
Merlin wrote this article https://www.valvewizard.co.uk/SRPP_Blencowe.pdf Second last page has the formula for the optimized unbypassed SRPP. I just plugged in the values for a triode strapped EL84, and it could work.
Erik
I had 16ohm EXO-35 OPT in my Bottlehead 2A3 Paraglow, which sounded excellent with 15ohm Lowthers.