Here is a chart I made in response to a question about direct 12ax7 substitutions. There are more than most people realize. The RCA manual designates the pinout as "9A", so I've included all "9A" pinout tubes here.
I've included all the industrial and military designations of these tubes also (where applicable), and arranged them in order of amplification factor. I did not include European designations like ECC83, etc. Hope this helps someone with their experimentation. As for which of these will work in certain applications, you'll have to do more research and conduct your own experiments. Generally, if a 12ax7 is called for in a certain position in one of your amps, probably any of these tubes will work as a drop-in substitute. The lower the amp factor, the less gain you'll get from that stage, which might be desirable. If the stage is a cathode follower and calls for a 12AT7 or 12AU7, subbing a 12AX7 or another of these tubes might create issues. I encourage you to experiment. This would actually make for a nice video comparing as many of these as possible. I think I have most of them in my tube collection already. If you'd like to see a video like that, let me know.
In this video, I put on the cloak of a preacher and talk about why the modern state of Israel spoken about in Genesis 12 is NOT the same as the modern state of Israel we see today and why this idea that we should never oppose Israel is a false teaching. I will back my argument up with Christian scripture. This is something I've never attempted to do before - offer up a Biblical teaching. I do not feel qualified at all. In fact, I am probably one of the least qualified preachers on earth. But maybe that's why you should listen anyway. If you have more to add, or if you have a rebuttal, feel free to comment. I'm all ears and willing to learn more.
This is a video response to Tone Priest's question about modding a Hiwatt clone build. If you are a paid member here on Locals and have tech or other questions, I'll be happy to give you a similar video response when I get time! Thanks so much for all your continued support.
This was the full jam session on the Gibson L1 I did recently. As you probably know, I usually will jam for a while on something and then pick a few highlights to show in a final video. A ton of stuff got edited out. It's not all great, but it's not all bad either. I find it kind of soothing, this quiet acoustic stuff. I'm never sure where the mood will take me.
This is probably the most overlooked aspect of your guitar tone hiding right under your nose.
What's going on here, fellas? On both these schematics the OT plates get B+ DC like normal through a bridge rectifier but check out how the screens and all the preamp tubes are getting juice. There appears to be a second tap off the secondary of the PT which goes through a choke, has a couple filter caps than straight in. How is this getting rectified???
https://el34world.com/charts/Schematics/files/Univox/Univox1061.pdf
https://el34world.com/charts/Schematics/files/Univox/Univox1086.pdf
