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.”

 

[RFR]

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.

I will say the mod did make the mic sound better.

 

[shmaller]

Have had an AKG Perception 220 for years and have never been able to get a good vocal out of it because the sibilance is just brutal. I learned how to be happy the day I just gave up and started using an SM57 for vocals. Recently I have been using the P220 as a room mic for acoustic and electric guitars and I do like it in that function, but it still feels like a waste somehow...

 

[LionKing]

Have had an AKG Perception 220 for years and have never been able to get a good vocal out of it because the sibilance is just brutal. I learned how to be happy the day I just gave up and started using an SM57 for vocals. Recently I have been using the P220 as a room mic for acoustic and electric guitars and I do like it in that function, but it still feels like a waste somehow...

The SM57 and SM58 are definitely reliable vocal mics.
Or, if you feel like experimenting, you could always try modding the P220 yourself!

 

[CoolCat]

weird.. I think it sounds a lot better on the cap swap and the AKG sounds smoother as described in the video, comparing to AKG pre and post.
I was impressed.

the AKG mod doesn't turn it into a Neumann U87..... but the mod did a noticeable "smooth upgrade" and closer to the sound of the U87.

As said above, why didn't AKG do this to start with?
Doesnt AKG even listen to the mics they pump out in the low end products?

The gear heads who find this stuff out is perplexing to me, who figured out this one cap could make it sound so much better? wow?

 

[Papanate]

The gear heads who find this stuff out is perplexing to me, who figured out this one cap could make it sound so much better? wow?

It is actually quite simple - people who know microphones know what changes when different parts are swapped out - it’s pretty much the same throughout -
and a Capacitor swap is the first thing - if you know the circuits right - but the sonics are shaped a little oddly - you start with the Capacitor - then maybe a Resistor -
a lot of the time it is the Capsule that is first altered , then the Capacitor to accommodate the Capsule - then sometimes adding or changing the Transformer.

 

[TalismanRich]

It's really too bad that a company as big as AKG with a full engineering staff, that's been in the business for 80 years and designed and built some very iconic mics can't figure out that a one part no cost change fixes a problem.

Or maybe that was their design choice to use the "wrong" capacitor value to give a brighter top end that appeals to some people.

People are funny sometimes. I was just reading a thread elsewhere. The poster had a Warm 8000 and wanted to know what capsule, transformer, tube and electronics should be changed to match a Sony 800G. REALLY? Other than the capsule, transformer, tube and electronics, what else is there?