Hoffman Amplifiers Tube Amplifier Forum
Amp Stuff => Tube Amp Building - Tweaks - Repairs => Topic started by: Papa Jim on March 15, 2019, 06:49:19 pm
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Other than not needing the screen grid wiring anymore, what would be the consequences of redesigning a fender Single ended 6G2 Princeton amp output section that has two 6v6GT tubes with one 6SN7 tube using both 1/2's of it instead of needing two separate tubes? :think1: No laughing please. Is it a complete impossibiity and I should move on or not.
https://el34world.com/charts/Schematics/files/Fender/Fender_princeton_6g2_schem.pdf
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here's my version I sketched up awhile back
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> fender Single ended 6G2 Princeton
Not single-ended.
6V6 can pass 100mA and throw 12W of heat.
Each half of 6SN7 can pass 20mA and throw 2W.
For a good fit you need a load impedance like 100/20 or five times what a 6V6 likes. This is in the area of 40KCT. It is hard to find an OT in that range. It still won't deliver 1/5th of the power of a 6V6 pair. So 1W-2W output. (in sight of shooter's 3W for two 6SN7.)
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2w is more than sufficient. I'm wanting to build a bedroom level amp. So are you suggesting possible with the right tranny for higher wattage, or absolutely possible for low wattage amp?
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See if there is some useful information here:
http://el34world.com/Forum/index.php?topic=18481.0
With respect, Tubenit
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The saying around here "So much for so little".
Cost benefit, wouldn't be more reasonable build an amp with watts selector?
Or something like the Vox Night Train 15 Watt Tube Amp Head with pentode/tetrode switch. It does 15w in one mode and 7.5w in the other.
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I'll take a look at those. Thanks.
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For a 12sn7/6sn7 p-p power amp, check out Simcha Delft's Moonlight Amp (Google around; there is a variant with a 12au7 I believe).
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Thanks I will check that out also.
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i understand where you are coming from you want your amp to growl but at a level that your wife/neighbors can tolerate. it is simply not that easy as prr stated. i thought i had found a way when i discovered the 6G6/G tube which is a power pentode with 2.75watts plate dissipation. it has the same pin out as a 6v6 and i was working on a silvertone se 6v6 amp that was too loud when i cranked it to a nice creamy saturation. i bought a used 6G6/g for maybe 6 or 8 bucks and when i plugged it in i got 2 surprises. 1st , the 6G6 sounded amazing. i mean this thing has killer rock and roll tone when i cranked the amp i was floored. 2nd was that it was not all that lower in volume. yes it was noticeably less volume but still pretty loud. when i took measurments the thing was dissipating 7watts at idle. which was my third surprise. so a tube doesnt just take the current it needs like some devices if the voltage is sufficiently high it will take the current that balances out via ohms law. point is you would have to mod the circuit to send less voltage to the plates/screens or else the circuit is going to squeeze more out of the lower powered tube then it was designed to handle. i figured what the hell. it (6g6) is a little lower in volume and it sounds phenomonal in this circuit, it didnt cost much so if it fries it fries... lol. i am still a newbie so i am finding the boundries of things . i design a circuit, usually cobbling together bits of other circuits with whatever transformers i have acquired and i see what it sounds like. if good then i tweak it a little until its great. if shite i dissasemble it. i am not the guy who builds fender tweed kits i want to figure out what is possible then creat my own personal tone nirvana. but that will take years hopefully.
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> fender Single ended 6G2 Princeton
Not single-ended.
Ok. so as kinda of a newbie I think you are meaning not single ended because it has two output tubes, but it is not PP either because for that doesn't it need a PI.
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The 6G2 is push/pull and it does have a PI.
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just typing that :)
I think, like me someone's confused
with one 6SN7 tube using both 1/2's of it instead of needing two separate tubes?
That would make it a PSE, no PI
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Okay learn something everyday. Just a lot different from PI I have seen so far, meaning the ones like you see in the deluxe reverb amp. I think the 5e3 has one like the 6g2. I need to read about how pi works. I need to spend more time with Merlins stuff I think before I try modifying, or else stick to a known schematic.
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Over on the AX84 web site there is a push pull 6SN7 power amp .It was also used in their October Studio design
http://ax84.com/static/corepoweramps/2W_PP/AX84_2W_PP_Poweramp_Schematic.pdf