KT88 triode with grid current is a good one Eli. How about 4x6L6oids in triode AB2?
Keeps the PSU simple, 400V and your golden. Backwards 9V primary transformer with two 115V primaries will make a nice +/- supply for the followers and hanging CCS for the front end.
Cheers
Matt.
Keeps the PSU simple, 400V and your golden. Backwards 9V primary transformer with two 115V primaries will make a nice +/- supply for the followers and hanging CCS for the front end.
Cheers
Matt.
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A variation on the trioded beam power tetrode in Class "_2" theme. 🙂 A quartet of Russian 6Π3C-E (6p3s-e) in each channel would be economical.
I have seen this one:
But it's working with two tubes.
I trust that i started to understand how a push-pull stage is working:
this is for one tube:is it right ?
[url=https://goopics.net/i/gAXRJ]
[IMG]https://i.goopics.net/800/gAXRJ.jpg[/url]
[/IMG]
But how it works with two tubes,please?
And on datasheet maximum voltage for 6as7g is 250v,i can see many schematics who voltage is higher as 300v.??
But it's working with two tubes.
I trust that i started to understand how a push-pull stage is working:
this is for one tube:is it right ?
[url=https://goopics.net/i/gAXRJ]
[IMG]https://i.goopics.net/800/gAXRJ.jpg[/url]
[/IMG]
But how it works with two tubes,please?
And on datasheet maximum voltage for 6as7g is 250v,i can see many schematics who voltage is higher as 300v.??
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Relatively high plate current and relatively low plate voltage. That seems to mate better with the step down ratio of the "iron". 4 Kohm primaries are what is commonly used with EL34s.
The obvious answer would be an EL34 PP amplifier. But did the original poster only have one transformer? In which case some sort of guitar amp is in order?
Some of the suggestions have been a bit esoteric. Speaking as someone who is still climbing the mountain, trying to absorb the information on invaluable sites like this one, it would be good if Marco Audio could state what expectations he has. If he is looking for a more turnkey solution, then a Baby Huey EL34 could be ideal, picking up a set of PCBs from the Group Buy section. There is an excellent community of enthusiastic builders of all levels of knowledge, so a good way to get the confidence to go to the next level.
Some of the suggestions have been a bit esoteric. Speaking as someone who is still climbing the mountain, trying to absorb the information on invaluable sites like this one, it would be good if Marco Audio could state what expectations he has. If he is looking for a more turnkey solution, then a Baby Huey EL34 could be ideal, picking up a set of PCBs from the Group Buy section. There is an excellent community of enthusiastic builders of all levels of knowledge, so a good way to get the confidence to go to the next level.
A pair of 6550's or KT88's can make up to 75 watts in triode AB2 with a 3300 ohm OPT on 450 volts. My test amp can be seen here:
75 watt per channel triode mode tube amp prototype - YouTube
A single pair of TRIODE wired 6L6GC's would be pushed a bit hard to make 50 watts into 3400 ohms. Four tubes would do fine, but I would choose a pair of 6550's or KT88's just for simplicity.
I tested a pair of really old 6L6GA's in pentode in the same amp seen above, again with the same 3300 ohm OPT's. I pushed the tubes hard to find their true limits. That limit was found twice with a tube arc occurring somewhere between 110 and 120 watts of power output. The amp was run for several minutes at 110 watts on 500 volts before turning it up with no issue. A single pair of 6L6GC's would be fine at 50 watts. The pictures show the tubes cranking out 112 watts in a dark room with nothing glowing. The image has been lightened for visibility.
As stated 3400 ohms was the usual load for many Marshall guitar amps running a pair of EL34's. They did not blow up despite some serious abuse, so a pair of EL34's would also be a valid choice.
I obviously ran some EL34's but don't seem to have the test data. The last pictures show the same amp with 6550's.
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