G7 build question

[deuc224]

Hi folks, ive done a search and cant find an answer, so any help is greatly appreciated.

First, i just got a Dales M7 capsule that i want to build the G7 with. My question is :

Do i have to change anything since im using an M7 instead of the ck12 capsule? Voltages, PSU, anything?

 

[Skylar]

Shouldn't make a difference.

Look out for the capsule membrane sucking into the backplate if the voltage is too high.
The capsule polarization on the G7 is 80V, which is probably about as high as you want.

If you're getting the sucking effect, reduce the voltage to the capsule.
There are two 470k resistors forming a voltage divider taking the 160V B+ down to 80V for the capsule.
IF you need to reduce the voltage to the capsule, reduce the the value of the second 470k resistor.
For example, a 330k resistor should give you about 66V to the capsule. A 390k would yield ~72.5V.

 

[e.oelberg]

maybe 80V Polarisation Voltage is  a bit much , a C12 Elam has 60v for the ck12

 

[Benny]

I didn't have to change any parts using Dales M7 capsule for my two G7s. I didn't actually measure polarisation voltages but they worked from first power-up without any changes from the original BOM.

 

[nashkato]

    I didn't have to change any parts using Dales M7 capsule for my two G7s.

    they worked from first power-up without any changes from the original BOM.

same here , though i never really had the full 160 Volts from the powersupply .
the B+ differed when using different powertransformers ,(especially on the reversed one) but i never got more than about 150V (75 polarisation voltage)
on 6 different powersupplies but all work nice with dales m7 and akg ck12.

 

[deuc224]

Nice!!! thanks a lot guys. I was worried about this because im a newbie and didnt want to make a critical mistake on my first mic build. One question really quick, now that i got the value for the high voltage to capsule, how will aq low voltage to capsule effect the sound or capsule?

 

[seavote]

i think there is a fairly large acceptable range. the G7 circuit calls for 160V. i thibnk many members ended up with about 145V. i purposely brought my B+ voltage down to 120V.
when i first fired up my G7 the circuit was at about 120V and humming because it was leaking to ground through a screw to the chassis. after i found and repaired the problem (i got about 160V)i didnt think the audio signal sounded as good as when it was humming.(i liked the sound of the mic minus the hum better than when it was repaired) very unscientific comparison i know.
so i lowered the voltage and i thibnk it "mellowed out"(less hi end?)the sound of the capsule.
a good thing i think with the peluso ck12 capsule i used.
build your G7 and see how it sounds. a different capsule may sound better at a different voltage. but you'll most likely be happy without any type of modification.