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Grounding Issue with TSB2590 #P48mems

 

So ive built an Ambi-Alice based on the Instructable by Jules and used em272 capsules. I noticed my mistake (that these are omni and not cardiod capsules) and ordered some TSB2590 knockoffs off of ali. They arrived and sound fine but I get a weird electrical buzzing sound wich gets amplified if i touch the capsules, so i suspect it could be a grounding issue.?
I used 4.7uF Capacitors and 100k ohm resistors for the simple p48 circuit wich worked great with the em272s and should also work fine with the new capsules right?
Is there a way to fix this??
The instructable doesnt use the cable shielding connected to the microphone capsule, could this help or am i gonna destroy the mics by doing that?

Any help would be appreciated :D
 

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I use the shield but only connect it to ground at the XLR. The capsules float at potential above ground and each one is a bit different. They need to be insulated from each other and handling. Also “real” TSB2590’s and I think the Primos have small internal 30pF or so for EMI Protection.?

Best Regards,

Jules Ryckebusch?

On Feb 10, 2025, at 19:13, gerttreggertert223 via groups.io <gerttreggertert223@...> wrote:

?
So ive built an Ambi-Alice based on the Instructable by Jules and used em272 capsules. I noticed my mistake (that these are omni and not cardiod capsules) and ordered some TSB2590 knockoffs off of ali. They arrived and sound fine but I get a weird electrical buzzing sound wich gets amplified if i touch the capsules, so i suspect it could be a grounding issue.?
I used 4.7uF Capacitors and 100k ohm resistors for the simple p48 circuit wich worked great with the em272s and should also work fine with the new capsules right?
Is there a way to fix this??
The instructable doesnt use the cable shielding connected to the microphone capsule, could this help or am i gonna destroy the mics by doing that?

Any help would be appreciated :D
 

The capsules themselves are properly isolated from one another. They also look the same as the originals and i doubt they would go through the steps to make a fake of the tsb2590s. I think they just come out of the same factory under a different name to sell them on other places.?
Is there a way I can reduce the voltage potential the capsules float at? Maybe by adding another cap somewhere? Im not an electrical engineer and honestly dont know what to google for in this situation.?

Thanks for your help :D
 

Maybe this is helpful. Ive attached both circuits of the datasheets of the capsules. On the left is the JLI2590a and on the right is the dr2501 I used. They look a bit different.?
Should i adjust the wiring?
?
?
 

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The one on the left is a 3-wire capsule, when the one on the right is a 2-wire.Depending on the circuit, they may be incompatible.
Apart from the buzz, does it work?

Le 11/02/2025 à 03:45, gerttreggertert223 via groups.io a écrit?:

Maybe this is helpful. Ive attached both circuits of the datasheets of the capsules. On the left is the JLI2590a and on the right is the dr2501 I used. They look a bit different.?
Should i adjust the wiring?
?
?
 

They work great except for the buzzing. Im just using a simple p48 circuit so 1 3.3uF cap and a 100k resistor on the xlr plug.
 

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Aah, OK! So the buzz is due to teh fact that the capsules are not properly shielded.

The shield must extend as far as possible to cover most of the capsule. Ideally, even the front of the capsule should be shieded. Of course, a mesh should be used, to allow sund to hit the diaphragm.

Le 11/02/2025 à 07:08, gerttreggertert223 via groups.io a écrit?:

They work great except for the buzzing. Im just using a simple p48 circuit so 1 3.3uF cap and a 100k resistor on the xlr plug.
 

They look to be shielded. ive attached a photo so you can see what im talking about.
They have Mesh in front and the body is soldered to ground on the 4 pads in the right picture. They should be grounded.
 

Yes, but the case doesn't?connect to the circuit ground (Pin-1) of the XLR's. In my instructable I run it all the way up to shield?the inner?two wires of the Mogami cable. I am also making the three?terminal Capsule into a "two terminal" by connecting S and G (Source and Ground). I have not had issues with this method and have used the 2590 in multiple projects this way.?

Jules

On Tue, Feb 11, 2025 at 9:18?AM gerttreggertert223 via <gerttreggertert223=[email protected]> wrote:

They look to be shielded. ive attached a photo so you can see what im talking about.
They have Mesh in front and the body is soldered to ground on the 4 pads in the right picture. They should be grounded.



--
Best Regards,

Jules Ryckebusch

214 399 0931
 

Would it be worth a try if i connected the cable shielding to the ground of the capsule case? Or am I risking damaging something by doing so?
 

On Tue, Feb 11, 2025 at 12:18 PM, @MusketenManfred wrote:
Would it be worth a try if i connected the cable shielding to the ground of the capsule case?
If you're using the simpleP48 powering scheme as specified in the Ambi-Alice instructable, grounding the capsule case will instantly and permanently damage the built-in FET. Don't ask me how I know this.
?
As mentioned, cardioid electrets are extremely sensitive to radiated hums and buzzes. You can test this by getting an empty soup can, ground the can, and carefully position it over your mic... you'll hear the buzz drop away.
?
So you need to come up with a metal mesh to shield the capsule and its wiring. Sometimes even two layers: something that shields each capsule, and then an overall mesh shield, like a metal mesh strainer.
 

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That wouldn't be worth a try because it just wouldn't work.

Le 11/02/2025 à 18:18, gerttreggertert223 via groups.io a écrit?:

Would it be worth a try if i connected the cable shielding to the ground of the capsule case? Or am I risking damaging something by doing so?
 

If you are using SimpleP48, you should download the latest version of SimpleP48.pdf from my Files.? Among other issues ...
?
  • 100k is almost certainly too large for TSB 2590.
  • I pontificate at length on the shielding required.
?
 

Id like to try the metal strainer approach. Where do I ground this to tho? Would I use a ground of one of the xlr connectors?
?
 

On Wed, Feb 12, 2025 at 12:26 PM, @MusketenManfred wrote:
Id like to try the metal strainer approach. Where do I ground this to tho? Would I use a ground of one of the xlr connectors?
Yes, connect the metal strainer to pin 1 of one of the XLR connections. It's easy to test if you can borrow a metal strainer from your kitchen. A test lead with alligator clips is useful here.

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