2 x 6AQ5 pushpull with 6X4 rectifier question

[Pedro Vecino]

Hello to everybody. I have interest to construct a small amplifier with two 6AQ5 in pushpull with fixed bias. It would use 3 12Ax7.
My question is if itīs sure to use a 6x4 rectifier with a output voltage of 250 volts or if it is not advisable (amp consumption longer than permitted the rectifier).
6X4 allows 70/75 mA. with 250 volts.
6AQ6 specs. in pushpull AB1 with 250 volts, here:
http://www.nj7p.org/Tube4.php?tube=6AQ5

The only amplifier that I know that uses this combination is the Gibson GA-5T Skylark.
This is the schematic: http://www.bymcomunicacion.com/pvecino/john/GA-5T.jpg
Thanks in advance

Pedro

[Rob Mercure]

Hey Pedro,

Your question is sort of confusing if you think about it - you are asking if a circuit will work while presenting us with a working example of one that did!

Yes it will work and the combination was used in several Heath Kits and EICO kits as well as a series of Bell and Howell film projector amplifiers (I've got 4-5 mil surplus that I've converted to guitar amps over the years - if you noticed the other 6AQ5 query that I responded to these amps formed the basis of the high powered 6AQ5 amps I made). As timelines go the 6AQ5 generally replaced the 6V6 in the USA - the EL84 wasn't "uncommon" but not as familiar as the 6AQ5 while the 6X4 generally replaced the 5Y3 as it was cheaper for manufacturers to avoid including a 5VAC winding on their PTs (the essentiallly identical 6X5 had preceeded it and the 6CA4 was a bit more expensive) so the 6AQ5/6X4 combination was fairly common in the USA during the 1960s.

Rob

[Rob Mercure]

Hey Pedro,

Your question is sort of confusing if you think about it - you are asking if a circuit will work while presenting us with a working example of one that did!

Yes it will work and the combination was used in several Heath Kits and EICO kits as well as a series of Bell and Howell film projector amplifiers (I've got 4-5 mil surplus that I've converted to guitar amps over the years - if you noticed the other 6AQ5 query that I responded to these amps formed the basis of the high powered 6AQ5 amps I made). As timelines go the 6AQ5 generally replaced the 6V6 in the USA - the EL84 wasn't "uncommon" but not as familiar as the 6AQ5 while the 6X4 generally replaced the 5Y3 as it was cheaper for manufacturers to avoid including a 5VAC winding on their PTs (the essentiallly identical 6X5 had preceeded it and the 6CA4 was a bit more expensive) so the 6AQ5/6X4 combination was fairly common in the USA during the 1960s.

Rob

[Pedro Vecino]

Thanks, Rob, and forgive my poor languaje. I think that Gibson GA5T is a small amplifier for practices and my idea is to do an amp to experiment with it cranked to limit.
I imagine that the Gibson GA5T will not exploit taking it to the limit but possibly the 6x4 limits (this was my idea, sorry) the regime of work more of the desirable by the approximation between the given current and the max. consumption of the amp producing an excessive sag.
The relations between rectifier model and max. compsumition sometimes they are capricious but normally the rectifier tube exceeds very much the max. consumption. In this case it seems to be very nearby.
I will look for information about these amplifiers and your collaborations in previous topics.
A last question: You say that generally 6AQ5 replace her 6V6. I imagine that it will be in minor powers (not the max. power of an 6V6 in pushpull with 400v). What safe power should have the output transformer using two 6AQ5 in pushpull with 250 volts across one 6X4? 12, 15 watts..?
Do you know some commercialized transformer that is adapted for it?

Forgive so many questions and thank you very much. They are tubes not known for me and literally I walk blindly