rodabod said:I should add to my original post, lowering the B+ is generally a good idea (as is removing the diode which lifts the heater voltage by 0.7V).
mitsos said:OK, since I already have it open... I traced out the schematic and it's more like the second PSU in the APEX mod packet (did I attach the whole thing?) so I've got 6.75V heaters. I was obviously measuring pre-regulator in the last post... oops.
So I took out the FR107 diode finally and I have a bit over 6V now... Closed up the PSU, and I think I'm done with this mic until I get a different tube. But that's a little while off still.
mitsos said:hi Kevin,
where did you get the RCA ribbon material? Was it already corrugated, right length and everything, ready to install? What did it set you back?
I'm assuming it made a huge difference?
alexc said:Just while on the subject of that long ago group buy, that tnc apex460 style mic ended up being quite a good mic, after reworking the circuit, tube and capsule. I think that came out at around 450usd.
I use that mic into one acmp81 feeding a diy la2a and it remains probably my best/most comprehensive mic chain.
Again, that led to a huge amount of learning as well as lots more time in focussed listening to the mic - indeed mics in general.
So, there is definately a 'happy ending' for at least some of the tnc stuff.