BeesNeez m7 Capsule in G7

[banio1208]

Hi
Is that a normal a that BeesNeez m7 Capsule have very poor bass, big boost in mids and 4-8k dip response in Cardio? Feels far away sounding, something like telephone effect, lo-fi alike
But in Omni sounds good, very linear
What you guys think?
Tube is E80F, and Lundahl 1538

 

[benqbasic]

No thats not normal. I don't have experience with the G7 circuit though.

 

[johnchantler]

What are your polarisation voltages? My understanding is that the m7 capsules can’t always handle the standard 80v of the g7

 

[ubxf]

could it be that you have your capsule wired backwards ?

 

[banio1208]

What are your polarisation voltages? My understanding is that the m7 capsules can’t always handle the standard 80v of the g7

Around 60V

 

[Delta Sigma]

Backplate not terminated properly? I have my BN M7 polarized at ~63V in an EF-U47 and it sounds fantastic.

 

[banio1208]

Update
When turned on after night
Sound is good for about a half hour
Later loosing lows and highs, and about 5db gain
Black magic…

 

[Delta Sigma]

Check backplate termination

 

[banio1208]

Here is measurements aligned
5,15,30,45 and an hour after turned on

 

[banio1208]

I did also measurements of front and rear rejection in Cardio
Seems weird...

 

[soliloqueen]

The fact that the difference is at 5K which is where the constructive and destructive interference happens in m7's front to back path and the difference in polar pattern suggests that maybe charge from the rear diaphragm is slowly leaking to ground? I've seen strange Behavior like this when both Center lead screws in an m7 are too long, but I don't think Ben would make a mistake like that. It's probably happening in your circuit somewhere.