My friend recently sent me a URL regarding driver with gyrator and source follower for GM70.
Is this the best solution to drive the GM70? But lots of feedback to make the gyrator works.
http://www.bartola.co.uk/valves/2018/03/13/gm-70-se-amplifier/
Is this the best solution to drive the GM70? But lots of feedback to make the gyrator works.
http://www.bartola.co.uk/valves/2018/03/13/gm-70-se-amplifier/
Where is the feedback mentioned? Just a classic design with a more linear driver with a hybrid mu-Follower (gyrator load) and well established dc coupled follower to the output valve on fixed bias
Not exotic at all to me
Haven’t built it, just suggested design based on my driver experiences
Ale
Not exotic at all to me
Haven’t built it, just suggested design based on my driver experiences
Ale
...It is very hard to buy pair of 6sf5gt.
6SF5 (6SF5GT, 6F5{G} w/top-cap) is half of a 12AX7 for most practical purpose. (Or rather: 12AX7 is two improved 6F5/6SF5 in one bottle.)
I forget what the Russian "12AX7" is called, but everybody has a hi-Mu triode, usually twin.
What do your guitar-amps use? That will work (with obviously different socket connections).
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WojtekSomething I can buy easily. It is very hard to buy pair of 6sf5gt.
Wojtek
For example:
6C45Pi, 2a3, 6s4s, 2s4s, 6s2s, 6s5s
I think that If you take the time to search around you will find what you need. There are plenty of examples using the russian valves you mentioned.
If you want western types, you should also consider D3a, 12HL7, amongst other valves which can swing 200Vpp at low distortion.
Have a look here for some examples: http://www.bartola.co.uk/valves/2018/04/01/driving-hard-part-i/#more-7330
Cheers
Ale
Something I can buy easily. It is very hard to buy pair of 6sf5gt.
Wojtek
Not at all. I bought the valve Ale describes , actually 16 RCA's with old logo in mint New-In-Box conditions, here: Electronic Tube and Valve Product Details
The price has gone up a little bit recently but still a bargain! 2x 6SF5 are cheaper than a chinese 12AX7....
Or rather: 12AX7 is two improved 6F5/6SF5 in one bottle
I disagree. The linearity of the 6SF5 is equal or better and it's more consistent. To find a 12AX7 where both triodes are as linear and matched as a matched pair of 6SF5's you need to discard lot of tubes....including some expensive old stuff!
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