AKG Perception P220 → Neumann U87 5-min Mod

[LionKing]

Hi everyone, I’m Lion
I recently found this forum by chance, and I really enjoy reading everyone’s insights here — there’s so much great information being shared!

I happened to come across something interesting related to mic mods — a quick AKG Perception P220 → Neumann U87 modification that’s been discussed on GroupDIY.

Here’s the full thread with the mod details:
AKG Perception P220 to Neumann U87 – 5-min Mod (P200/P100/P400/P420)

And here’s a sound comparison video — it shows the modified P420 side by side with a real Neumann U87:


I thought this might be interesting for those who enjoy DIY mic mods and like testing how close these projects can get to the original classics.
Has anyone here tried similar mods or compared Perception-series mics with the U87?
Would love to hear your opinions on how close this one gets.

Cheers,
Lion

 

[Papanate]

Right - it doesn’t sound like the U87 at all - it sounds like a small improvement of the midrange response- I’d heard about this mod - and as usual the guys modding the AKG Perception P220 act like it’s the second coming -

 

[RFR]

U87 is much warmer sounding to my ear. And that’s just from listening to it on my phone. I can only imagine the difference listening on good monitors.

 

[TalismanRich]

The change has been around for several years. The mod is rolling off the top end, and different people suggest different values for the capacitor change. 680pF is the most common value, but I've seen people choose 870 or even 1000pF and it HAS TO BE a sytroflex cap. I think it might be the variations in the individual microphones that account for the differing opinions. I've also heard people making changes to the JFET bias but that takes more work.

The inevitable outcome is a vastly improved mic with the veils removed, the harsh sibilance disappears, and the bright lights from the heavens shine down.

What I find interesting is that AKG could very easily change the 220pF SMC to 680 at no cost. So the question is why did the engineers choose the wrong value in the original design, and why hasn't the company corrected the mistake after all these years? They could call it the MkII version and up the price by $50! Pure profit ahead.

 

[LionKing]

U87 is much warmer sounding to my ear. And that’s just from listening to it on my phone. I can only imagine the difference listening on good monitors.

Good point — that warmth you’re hearing probably comes from the U87’s capsule and transformer design.
The P220 mod changes the voicing a bit, but it can’t really reproduce that same low-mid character.
Still, it’s fun to see how close people can get through circuit tweaks.

 

[LionKing]

The change has been around for several years. The mod is rolling off the top end, and different people suggest different values for the capacitor change. 680pF is the most common value, but I've seen people choose 870 or even 1000pF and it HAS TO BE a sytroflex cap. I think it might be the variations in the individual microphones that account for the differing opinions. I've also heard people making changes to the JFET bias but that takes more work.

The inevitable outcome is a vastly improved mic with the veils removed, the harsh sibilance disappears, and the bright lights from the heavens shine down.

What I find interesting is that AKG could very easily change the 220pF SMC to 680 at no cost. So the question is why did the engineers choose the wrong value in the original design, and why hasn't the company corrected the mistake after all these years? They could call it the MkII version and up the price by $50! Pure profit ahead.

I totally agree with you — and an even more fun approach is to wire in a small variable capacitor, so you can fine-tune the top end by ear.
AKG always seems to tweak the circuit a little when they copy a classic design — just enough to make it “different.”