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?

 

[R D Smith]

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.

Like you said earlier, just make a new part number, change the response curve in the documentation, and market a new microphone for zero costs other than documentation and packaging expenses.

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

Yes. The company I worked for made some products with specific performance curves for niche market customers. Just a different program in the micro processor. They cost the same to make, but you have the added cost of another part number and product with low volume so you charge more. The retailer markets it as better because .... etc....

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?

All it really takes is a credit card with a high limit!

But seriously, most people mod things because they like tinkering. If they think it sounds better or more like "X" product, great.

 

[TalismanRich]

But seriously, most people mod things because they like tinkering. If they think it sounds better or more like "X" product, great.

I'll bet there's a thread on a Fender forum where someone bought a Squire strat, put on an AllParts strat body, a Warmoth neck, new Am vintage Strat bridge, new Lollar pickups and a custom pickguard, and CTS pots and PIO caps and new tuners. That Squire now sounds as good as a $1800 Professional II strat and only cost $2400!

 

[R D Smith]

I'll bet there's a thread on a Fender forum where someone bought a Squire strat, put on an AllParts strat body, a Warmoth neck, new Am vintage Strat bridge, new Lollar pickups and a custom pickguard, and CTS pots and PIO caps and new tuners. That Squire now sounds as good as a $1800 Professional II strat and only cost $2400!

No doubt!

 

[CoolCat]

add this a year later- Sept 2026-

I just added the cap to a P420 the other day.
Was it 5 min fun solder job? no.... actually it was 5 minutes of intense fear of holding a 620F solder tip hoping not to destroy a perfectly fine ,brand new, mic with Surace Mount, so incredibly tiny!! whats truly amazing is a person didn't "mess up" the mic. I did the add-on cap to the existing cap, as in the video below. Instead of removing and installing one capacitor. Its the Black P420. 220 add a 471...pico farad.

Results:
Pre Mod and Post Mod, is noticeable but for me the mic was ok Stock too. The point is King Korg of DIY fame did a lot of work to determine the graph-and freq to match the U87ai. So taking his word and experience you just copy and use the numbers he used. (kind of like AKG copying the U87ai circuit).
If you don't have a high freq issue to begin with maybe its not massive change but ok its noticeable on a dry raw track and it the point is to MATCH the U87ai SOUND not make it better than a U87ai, under a microscope as they say. The video above both U87 and AKG sounds processed a bit. imo. It sounds better than my U87ai sound and dry non processed mic. I was really underwhelmed with the U87ai (circuit #6 (which is supposedly one of the best U87ai circuit revisions).....so whatever, to each their own ears.
It just sounded so plain and normal the price didn't get me any "magic, rainbow, beatlesEMI sound suddenly".

The DIY-
I did the same blue cap, Amazon $5 for 10qty. as the video below .
Listening to the P420 and the U87ai in my own tracks,....the U87ai for me is not a preferred sound and the P420 matches it closely imo....
in mixes and in videos it is what it is, U87ai sound is a classic standard so I can accept this is the "industry standard LDC".
Accepting King Korg and all the YouTube's on this work shows AKGP420 is close as the video above says "maybe a little clearer" than the U87ai. High sensitivity mic, its not a warm sounding mic King Korg was tweaking to match the U87ai.....not improve it to sound better than a U87ai..

adding 470 pico farad to the existing 220 pico farad. was my choice fter seeing how tiny Surface Mount is.

I don't think the soldering DIY is impossible but its not easy at all, imo. Its not as easy as soldering XLR jacks on a mic cable.
Yes, once its done, ok...5 minutes..if all goes well and everything is setup and works.
Surface Mount is incredibly tiny..omg

If a Guitar Cable is Entry level or 1 of 10 being harder, this DIY would be 5-7 imo due to tiny size and possibility of ruining a good mic.

2:36 and 10:56 is the AKG P420

 

[LionKing]

add this a year later- Sept 2026-

I just added the cap to a P420 the other day.
Was it 5 min fun solder job? no.... actually it was 5 minutes of intense fear of holding a 620F solder tip hoping not to destroy a perfectly fine ,brand new, mic with Surace Mount, so incredibly tiny!! whats truly amazing is a person didn't "mess up" the mic. I did the add-on cap to the existing cap, as in the video below. Instead of removing and installing one capacitor. Its the Black P420. 220 add a 471...pico farad.

Results:
Pre Mod and Post Mod, is noticeable but for me the mic was ok Stock too. The point is King Korg of DIY fame did a lot of work to determine the graph-and freq to match the U87ai. So taking his word and experience you just copy and use the numbers he used. (kind of like AKG copying the U87ai circuit).
If you don't have a high freq issue to begin with maybe its not massive change but ok its noticeable on a dry raw track and it the point is to MATCH the U87ai SOUND not make it better than a U87ai, under a microscope as they say. The video above both U87 and AKG sounds processed a bit. imo. It sounds better than my U87ai sound and dry non processed mic. I was really underwhelmed with the U87ai (circuit #6 (which is supposedly one of the best U87ai circuit revisions).....so whatever, to each their own ears.
It just sounded so plain and normal the price didn't get me any "magic, rainbow, beatlesEMI sound suddenly".

The DIY-
I did the same blue cap, Amazon $5 for 10qty. as the video below .
Listening to the P420 and the U87ai in my own tracks,....the U87ai for me is not a preferred sound and the P420 matches it closely imo....
in mixes and in videos it is what it is, U87ai sound is a classic standard so I can accept this is the "industry standard LDC".
Accepting King Korg and all the YouTube's on this work shows AKGP420 is close as the video above says "maybe a little clearer" than the U87ai. High sensitivity mic, its not a warm sounding mic King Korg was tweaking to match the U87ai.....not improve it to sound better than a U87ai..

adding 470 pico farad to the existing 220 pico farad. was my choice fter seeing how tiny Surface Mount is.

I don't think the soldering DIY is impossible but its not easy at all, imo. Its not as easy as soldering XLR jacks on a mic cable.
Yes, once its done, ok...5 minutes..if all goes well and everything is setup and works.
Surface Mount is incredibly tiny..omg

If a Guitar Cable is Entry level or 1 of 10 being harder, this DIY would be 5-7 imo due to tiny size and possibility of ruining a good mic.

2:36 and 10:56 is the AKG P420


View attachment 153334

I have to say, I’ve really come to love the sound of my own modified P220 as well. The original voicing had a pretty aggressive top end to my ears, and the difference after the mod was actually quite noticeable.

Also, if anyone unfortunately damages the solder pad during the modification, it may still be possible to recover it. There’s a good example in the discussion around page 30 of that thread — you can simply stack another capacitor on the nearby capacitor to achieve the desired value.

For example, if you originally have 220 pF and want to add roughly 470 pF, you can use a single 680 pF capacitor instead. It’s a pretty simple workaround if the original pad is damaged.

 

[rob aylestone]

Is this kind of thing not just EQ, but tweaking the curve inside the mic preamp rather than externally?

 

[CoolCat]

The "stacking" is a good term, that's the method I used. It looked easier to do imo.
Shown in the picture, the blue-cap is "stacked on the 220pf.
220pf is still on the board, the "stacked-added" 470pf is in parallel= 690pf.
If a person wants to go back to the original they can remove the added cap, though I don't see what the point would be to remove it.
The lower video Blue Grass dude used the "stacked " method. Many others removed the 220pf and installed a 670~ pf, that looked much harder to do...as its so tiny a part!

It was all based off the U87ai response curves King Korg was comparing too. How he got to that component is over my head.
King Korg obviously knows the U87 circuit components and each has a purpose. KingKorg knew what to fine tune.
Being the AKG P420 is a directly copied U87ai circuit. As the top video Mic Assasin mentioned, there are even unused components in the U87ai circuit and AKG Perception Series even copied those too!

so the Capsule was the key but the Takstar Capsule seems to have nailed the K87 capsule really well, and supposedly the King Korg mod does a fine tweak to match the circuit better to the Takstar capsule to align to the U87ai curve he had with "his U87ai."

"the Industry Standard LDC" hmmm?
interesting confusion, because per Klaus, Nuemann repair guru, often mentioning differences in the Neumann u87ai's and which circuit version 1 to 6 ...or which capsule is better or crap, or which FET was used... making the mic being copied having variations.... Klaus made me wonder if the U87ai I had was a "crap" one....because listening to the tracks I have its pretty blah, and non magical. So I bought original Texas Instrument FET from the earlier 87 days before the Fairchild FET were used...(but never soldered it in)
...but I sure wasn't impressed. I will add positive I was impressed with the Quality, fine build and workmanship of it....but then it didn't even come with a shock mount... I bought a $20 one that fit well. so add that to the $1900 used price.

 

[CoolCat]

I snagged another USED U87ai. w/45 day return from Guitar Center ..really a such a decent price for 2026 on this one.
Ill take it apart when it arrives and confirm its real. If the blue seal is in tact I might not pull the capsule out this time, that's a tough decision.
If the blue wax is already removed or the stamp is altered then definitely will remove the head basket. A person can see the capsule through the head basket, its
just not as easy.

Will compare some tracks to the other one I had. Still have the shock mount ...
Curious ...as time allows will make a few tracks and compare to the "modded P420" .(now on sale at $149 Amazon)..

of course it should sound very close, Im guessing, why wouldn't it?