Has anyone built a custom noval to octal tube socket converter?

[kato]

All my EF86 tubes (for U47 microphone) were deselected by the sellers who ebayed them, and have way too much noise for microphone use.

Interestingly, I have a bunch of 6SJ7 tubes I could try, but they're octal sockets. I found some socket converters on eBay. They won't work for EF86 to 6SJ7, but I'm wondering if I can take these apart and rewire them internally.



I'm just thinking out loud if you folks have any thoughts. I realize I would need a giant ass mic body to fit this sort of thing. But I have a BM-95 on the way, which I'm hoping is large enough to fit, at least for experimentation.

What's the best advice? Should I just stop dicking around and buy some properly tested EF86's?
It's $18 just for the converter, which I could probably better put toward a good tube.

 

[kato]

I checked all the known socket converters I could find, and none of them pin correctly.
This is just my scratchpad. Fair warning, none of the 3 I found would do EF86 to 6SJ7 as sold.

 

[Tubetec]

Ive used EF86's with PTFE valve bases in a U47/Elam type design . Space is usually fairly limited in mic bodies , you might also add signifigant incidental capacitance and possibly leakage using an adapter . Im not sure how well a 6SJ7 would tollerate the sorts of grid resistor values found in tube mics. Sony seemed to favour the 6AU6 in the C37a, C800 and C800G , again not every specimen will handle the high grid resistances involved so testing for noise would be required .

 

[kato]

Ive used EF86's with PTFE valve bases in a U47/Elam type design . Space is usually fairly limited in mic bodies , you might also add signifigant incidental capacitance and possibly leakage using an adapter . Im not sure how well a 6SJ7 would tollerate the sorts of grid resistor values found in tube mics. Sony seemed to favour the 6AU6 in the C37a, C800 and C800G , again not every specimen will handle the high grid resistances involved so testing for noise would be required .

Hey, thanks for chiming in. I never considered the added capacitance from a socket converter.

I have a bunch of 6AU6's. Obviously not pin-compatible, but I've never seen mention of anyone trying a conversion so it's probably not worth the effort to pioneer that adventure.

I think I'll just pay for a well-tested EF86 and move on. But I appreciate you entertaining my train of thought, Matthew

 

[Tubetec]

Glad to be of assistance Matthew,
I was lucky enough to collect a handfull of Mullard EF86's used but in good nick , pulled from old preamps etc . Probably not such a commonly used tube stateside , sometimes its worth buying old amp chassis just for the tubes they contain .