AKG Perception P220 to Neumann u87 5 min mod ( p200, p100, p400, p420? )

[kingkorg]

Sorry but no, you got it wrong. The mic and it's transformer is just fine. Of course you get the lack of bass if you load the mic with that low impedance.

Input impedance of a pre should be about 10 times, or more, higher than mic output impedance. Perception has just like the u87 output impedance of 200 ohm, so you need idealy about 2K pre. Whatever you are experiencing with the Perception you would get with the u87. And that's why you have the switch on the pre.

If you use 6:1 you'll just increase the noise as you will lose level.

If you are using 1073 to measure mic's noise it's not a good idea. 1073 is not a quiet pre.

 

[oscarhuang]

 

[oscarhuang]

Now the problem is solved. Very happy with this mod. 300 ohm input impedance is works good now. And the self noise is quieter. I didn’t changed the 220pf. I tried 680pf and it’s too dark for me. But big thanks to KingKong to provide the idea and that why I like here.

 

[k brown]

Hi people,

As we all know Perception circuits are pure ripoff of u87, but don't sound like one because of the capsule. A fellow musician sent me vintage u87 to clean super dirty capsule, and two AKG P220 to try to match the sound to Neumann.

I found out by comparing and measuring the two, for some reason AKG has weaker HF attenuation, and brighter capsule. I just wanted to report that Neumann u87's C6 capacitor responsible for HF de emphasis network is super easy to reach and change.

By measuring frequency responses of u87 and P220 i came to conclusion that it needs to be changed to an 680pF capacitor, instead of original 220pF. You get incredible replica in minutes. It's just that Perception has better bass response , because i t's bass roll off is weaker as well. I didn't want to touch that. I sent files of the shootout to the owner, he picked wrong one to be Neumann. Probably due to AKG's better bass response. Akg is louder, and has less noise. Modded even less due to more HF attenuation. By googling i found that people report this cap to have up to 870pF in some Neumanns. This value gave me u67 kind of response.

No need to disassemble any boards, it's right in front of you when you open the mic. This should work for other Perception mics as well. Might be tricky for newbies to remove smd cap.

One thing to add, AKG is built like a tank!

I'll upload audio files and frequency response graphs tomorrow.
Here is the cap we are talking about.

Just to clarify - is this about the Perception 220, or the AKG P220? Was there a third model called "AKG Perception P220"?. Or are the boards identical?

 

[kingkorg]

All the same

 

[k brown]

Groovy, thanks.

 

[oscarhuang]

Just for fun. I like the Cinemag transformer in the this mic. I will compare it to U87ai. Should be very close now.

 

[ubxf]

how do you change the impedance on a 1073 ?

 

[kingkorg]

how do you change the impedance on a 1073 ?

I guess it's one of the 1073 based knockoffs, like Alctron, Golden Age...

 

[Khron]

how do you change the impedance on a 1073 ?

By wiring the two halves of the input transformer's primary either in series (to get "1200 ohm"), or in parallel (to get "300 ohm").

 

[ubxf]

Thank you, so it's either a rewiring or a mod with a switch. The 10468 is normally 1200 ohm 1:2
In what case is it beneficial to wire it for 300 ohm ?

 

[oscarhuang]

I am using EZ1073. Here is the input transformer for 300ohm and 1200ohm.

 

[k brown]

Even with the mod, I became rather disenchanted with the sound of the chinese capsule and swapped it out for an Oktava MK-319 capsule; with the original capacitor back in. Gives me a more useful 'alternate color'.

I'm curious to try this edge-terminated one out in it - if the graphs shown are at all accurate, could have a nice, flat C-37a-like sound?
https://www.ebay.com/itm/1447950177...EErV9q7qyke6DkNavf4mrHXt3gTj|tkp:BFBMgK3DwY9hAnyone seen this one before?

 

[k brown]

Even with the mod, I became rather disenchanted with the sound of the chinese capsule and swapped it out for an Oktava MK-319 capsule; with the original capacitor back in. Gives me a more useful 'alternate color'.

I'm curious to try this edge-terminated one out in it - if the graphs shown are at all accurate, could have a nice, flat C-37a-like sound?
https://www.ebay.com/itm/1447950177...EErV9q7qyke6DkNavf4mrHXt3gTj|tkp:BFBMgK3DwY9hAnyone seen this one before?

Back to report that I'm very pleased with this capsule. Just what I was looking for - an externally polarized 34mm edge-terminated capsule with a nice Sony C37A-like response - no top end hype that needs attending to. Waaay worth the price ($22)! Worth thrice the price.

It looks very much like a single-diaphragm version the brass CK12 capsule, but without it's 5dB bump at top. It's actually a dual-diaphragm, but the back one isn't sputtered (as with the Oktava 219/319). The clear rear diaphragm isn't apparent in the photo. There's nothing cheap-looking about it's construction. Came in the same square, clear box that the expensive one do.

This is staying in the AKG, I have a tube mic with an Oktava 319 capsule in it; I'll use that for it's 'alternate color'.

Anyone know who makes this capsule? Shipped from Pennsylvania. Several different sellers offering the exact same item (at least pics are the same!).

 

[k brown]

Wondering now if one couldn't take the front diaphragm off of one and put it on the back of another?

 

[Khron]

Physically, probably - done that with a few sE electronics single-sided k67 capsules, just for kicks. No guarantees regarding if or how closely matched the sides are, nor have i had the chance to put them into any mics just yet...

 

[k brown]

At this price it's definately worth a try - I don't know of any other $45 flat-response dual-diaphragm capsules.

 

[Khron]

Figuring out which screws are for holding the halves together can be interesting, but it'll be best to do that on the non-metallized side, for obvious reasons (no harm done if the diaphragm is not glued, and potentially loses some tension).

Once you find one, the other one on that side is diametrically opposed, and the two from the other side will be @ 90deg from those.

 

[k brown]

Thanks for that.

 

[Khron]

Bit of a shameless plug, but i documented that exact process, at the time

https://khronscave.blogspot.com/2017/05/a-litle-k67-microphone-capsule-fun.html