I'm planning on building one of these FET847s. I have the board, and I'm probably going to use a G2-2B body.
Is there a good source for the Cinemag 5722 transformer? What other transformers are good? I'm guessing the AMI T47, or BV8 would be good alternatives, with their 6.5:1 ratios?
fsalter said:I would highly recommend 3U's GZT-84. I've used it on several builds and have not been disappointed. The price is right too.
JMPGuitars said:I'm up for trying them out, but wouldn't the GZT-47 be more appropriate with the 6.5:1 ratio?
Anyway, maybe you could try that 47 and use two low input capacitance JFET's or single dual (LSK489) in parallel like on Telefunken TF11 (https://www.telefunken-elektroakustik.com/microphones/tf11).
mhelin said:Yes there are also other factors like the transformer inductance and the load of course which depends on which preamp you will use.
It's odd that the CM5722 datasheet first says "Microphone Output Transformer 9.5:1 Step-down BV-107 Style" and then later tells the turns ratio is 6.9:1. Anyway the response is specified for Rs=10k and Rl=1.5k.
When I go to the order page at https://www.vintagemicrophonepcbkit.com/orders.html, the 847 boards are the last thing on the list.Ricardus said:Is this project long gone and is there no more board availability? Anyone got 2 boards they aren't planning to use?
craigmorris74 said:When I go to the order page at https://www.vintagemicrophonepcbkit.com/orders.html, the 847 boards are the last thing on the list.
Did you ever resolve this? If not, check that the capsule connections are good on both ends (carefully!).Hey there,
I've been using my fet847 for a few years now and was very happy with it !
Today I wanted to replace its RK12 capsule for a Beesneeez K47 because I've always wished this mic had more mid presence.
But now the mic as very low volume so when I adjust gain for enough level I obviously get a lot of noise.
Adjusting the bias isn't helpful here.
I've checked & cleaned my soldering many times.
Any clues ?