. . . I must confess that I don't really understand this part of the thread. I'm looking for a mod kit under $100 that could help me get a sound close to the U87ai. Do you have a suggestion for an affordable mod kit or pieces ?
Bonjour notre ami. Je parle français, mais juste un peu.
I offer a sincere, yet possibly unpopular suggestion: Perhaps you could wait to modify your microphone until you know more about the process, in general, and what sound qualities to expect, in particular? I understand and appreciate everyone wants to get started and DO SOMETHING to get started NOW. But, there is little advantage to modifying a microphone just to modify it. The modification should be carefully selected and well calculated to achieve a particular, known improvement or altered sound profile. I am a huge fan of home brewed electronics projects, but one should not modify any microphone just for the sake of changing it.
I consider learning about a hobby the most important aspect of a hobby. For example, I enjoy learning about antennas, radios, and building a competent station more than operating and making contacts on the air. (Crazy, eh?) Similarly, I enjoy learning about microphones and good recording technique more than running a recording studio. (Really crazy, eh?)
I am concerned you may not fully know what you want to accomplish and how to do it. With a budget of only $100 US / 97.19625 Euros, you cannot afford to make mistakes.
I do not believe anyone can make a $100 Perception microphone sound exactly like a $3000 Neumann U87i. But more to the point, I wonder why you want your microphone to sound exactly like a U87i? I suspect it is because the U87i is famous for recording great music. While I understand the U87i is revered because so much great music was made with it - I suspect great music made the microphone famous, not the other way around! The music would have been great if recorded with a different microphone, perhaps making it the proverbial gold standard, instead. Why would I want to use the best microphone in 1970, when I can use the best microphone in 2025 - as if there has never been anything better in all these years. (Of course, I may be all wrong and the U87i really IS the best ever ... my point is I do not comprehend the point of buying Microphone A just to make it sound like Microphone B - In that case, I just save up and buy Microphone B.)
As you are new to this, I suspect you are still developing your personal recording and mixing style. Ultimately, a U87-like microphone may not best suit your personal style in the long run. Why limit yourself to just one sound when you are just beginning to develop YOUR sound? It is possible your sound would be better captured with an AKG C414, or Sennheiser MK8, or AustrianAudio OC18, or (perish the thought) a pair of well-placed, low cost, pencil-style small diaphragm condenser microphones which do not look as cool, but have their uses.
I offer this suggestion because many novice microphone mavens want to DO SOMETHING as quickly as possible, perhaps because they are naturally and understandably chomping at the bit to ... um ... DO ... SOMETHING ... as soon as possible. (Yes, I have often been there, myself!)
Therefore, I suggest with all respect, that if you have a small budget, you spend a LOT of time researching and learning what modifications are available, which are most popular (and why), and what sound profiles they produce (and why), before you do ANYTHING to your lovely AKG Perception microphone - which has a good reputation among consumers for sounding pretty good as is. I suggest you thoroughly research all such modifications, even before making the simple modification which is mentioned by other members earlier in this thread. That will help you make an informed, well planned decision, and assure you achieve a result you will like in the long run. OR, you can make their suggested simple, low cost modification, and save the remainder of your budget for other projects later on. In any case, do not take our word for any of this - do your homework and reach your own conclusions before cobbling anything up in the workshop.
I mention all of this because, I fear you are anxious to modify your microphone - lacking sufficient justification or reason for doing it. My assessment is reinforced by the fact you are unsure what sound profile will result from the modification, and do not understand how the modification alters the original sound. I believe you would benefit from a long, deep dive into the theory and basis for various modifications, of this and other microphones, before selecting just one low cost modification to make, hoping for a U87i-like result. After all, unless you are VERY familiar with how a true U87i sounds, you can only take other guys' words for how it sounds!
Personally, based on my own research and experience, I truly doubt your AKG Perception will every TRULY sound like a Neumann U87i. This is an example of the age-old "cannot-make-a-purse-from-a-sow-s ear) sort of fallacy. I truly do not believe ANY microphone can be modified for any price, let alone for a mere $100 /100EU, and truly sound like a Neumann U87i. Shoot, if that was possible, EVERYONE would do the simple capacitor mod proffered above, saving thousands of dollars, selling their high priced Neumann models to lazy, poorly informed recordists who do not know the "secret" to achieving "THE sound" without paying the price.
How did you determine the U87i has the "right" and "best" sound for YOUR recording projects? Researching the available options, and the basis for such modifications, will either confirm or cancel your order for a U87i-like sound. Sticking my neck out even more, I have heard the U87i and, crazy as it sounds, I would not pay ten dollars for one! (OK, I would, but surely you get the point!) Of course I recognize this is "microphone blasphemy," but I do not want MY music to sound like it was recorded in the late 1960s. While I LOVE music from that period, I also wish to enjoy the latest, greatest improvements developed over past 50 years since then. OK ... there I said it ... and I am sure I will be blasted and hounded out of the principality by umpty dozen (real) experts for saying so! (I mean, Sheesh! You have no reason to take MY word for any of this!)
And yet, I ask why you want your microphone to sound like another one - what will that do for you? How do you know that is the sound profile you really want or need? Why not make it sound like other legendary recording gems from AKG, SONY, Shure, Telefunken or BeyerDynamic? Or, why not sell your low cost AKG Perception microphone and combine the proceeds with your 100 EU budget, skip a few dinners out, and buy something really boffo for $250-$300 EU, and get a truly great microphone with its own reputation for great sound, that might, also, better suit your personal recording style? While it is fun to modify microphones, and I am HUGE FAN of home brewed electronics projects ... on a tight budget, you may wish to perform much more detailed research before making a decision as to one particular modification. I wager, over time, you will complete a very different project better calculated to achieve a specific, known, objective that suits your personal recording style.
Nothing in this message is intended to be or sound critical or snarky or denigrate your question or your objectives. I make this suggestion solely because I have been in the same place as you many times, and truly believe you should learn more before doing anything in particular. I offer this advice solely as a brother, hoping you get along with YOUR brothers!
HAPPY TRAILS to you. Good luck. / James /
(Sidebar - I suggest one can save money by avoiding French restaurants with great hesitation, as I have toured France multiple times and KNOW how wonderful French cuisine is! Nevertheless, it is an easy way to save money for microphone projects!)
Bon appetit, mon ami. / JHR /
