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

[Khron]

Roger.

And yet, ... er ... um ... I suspect a glop of hot glue is more likely reversible than, say, an equal portion of CA (cyanoacrylic) "super") glue. James

That's a good point, although i don't think i recommended CA / super-glue (or any other kind, for that matter) Reversibility, especially since this is DIY / modding, can only be a good thing

 

[negaikast]

I just received my HL-95 body and contemplating moving the guts of my modded p420 to the HL-95. Will return with results.
Always wondered about the transformer though. Anyone tried replacing it with a better option?

 

[mikes425]

Im back
My brand new (black) perception 420 came in today plus my 680pf capacitors from mouser.

Ok lets try this again,this time leaving in the 220pf smd
And soldering in parallel on to it the 680pf for a total of
900pf

I thought I wouldn’t like this, I LOVE IT!! Super mid rangy creaminess!! Im guessing im in the tlm67/ u89 territory?..

My 470pf will deliver tomorrow but i think im going to leave this as is for now since i own a real u87ai. I think it compliments it well in the mic collection

Oh and im still using my blue housing from my p420 i destroyed
I dont like the new black housing.

Just for clarification and sorry for duplication of a prior post that i can't find... So if i want to do a P220 mod, (since a 200 i sent out for this was not modded right) -which would be your preference in Cap value to match the 87Ai (versus Vintage 87) as faithfully as possible, if replacing the stock 220 cap?
I believe the recommendation was in the realm of a 540 or 560p, whereas a 600+ leaned more into the
U67/vintage character...and that 470pf might be a bit overly bright. Does that sound about right? Thanks!

 

[cholmes777]

My guess is 470pf - 680pf is the sweet spot for u87ai land....

 

[LevinGuitar]

You got the same sound as me. It's delicious. Yep, looks like it's somewhere
towards TLM67.
Have you dressed the new P420 black with Perception420's blue clothes?
Could you do a comparative sound test between U87ai and P420 mod, possibly a test with Pink noise to see graphically the frequency response differences?
I repeat myself, but the damaged microphone needs to be fixed, made to sound good.

How can the TLM67 be that flat? I thought the circuit was flat, and since the capsule is the k67... what I'm missing?

 

[micolas]

How can the TLM67 be that flat? I thought the circuit was flat, and since the capsule is the k67... what I'm missing?

Hola amigo!Que tal?
It's simple
The TLM67 circuit is not flat.
They pushed de-emphasis even further than in U87ai
In addition, it seems that they analogically emulated the specific saturations of the tube/transformer to obtain a sound closer to that characteristic of the U67. Some are happy with this emulation, I find it unconvincing.
I think @RuudNL has studied TLM67 more, he knows how much de-emphasis it has at different frequencies, he's very pedantic, objective, analytical,
he likes to document himself thoroughly.

 

[LevinGuitar]

Hola
I wonder how they did the EQ on the circuit. Will look for a spare pcb if see a cheap one. Saturation emulated with a fet or opamp :/ ?
They should have used a internal switch to disable that feature at least.

 

[micolas]

Hola
I wonder how they did the EQ on the circuit. Will look for a spare pcb if see a cheap one. Saturation emulated with a fet or opamp :/ ?
They should have used a internal switch to disable that feature at least.

For now we don't have a scheme.
Buildings made with SMD technology, which are increasingly common, are quite difficult to decipher, the components are difficult to measure when soldered, the value markings are sometimes missing, proprietary codes are used, etc.
Especially in the TLM series, Neumann/Sennheiser are very secretive, in some cases they ended up hiding different sections in discrete integrated circuits, or masking the PCBs with opaque coating

 

[LevinGuitar]

Well, difficult does not mean impossible. Its a matter of time

 

[micolas]

Well, difficult does not mean impossible. Its a matter of time

Well, we look forward to learning more about the technical artifices used in more modern microphones. Maybe you can find a TLM67 at an attractive price and manage some reverse engineering, I searched without success.
Some prefer to convert them to U67
since the capsule, body and headbasket are similar.

 

[micolas]

Let's stop polluting the thread, when we have more substantial information relative to TLM, we will address the subject in a dedicated thread

 

[mikes425]

Seeking some perspective on this... I asked a tech to perform the mod on a Perception 220 and as posted previously, they modified a different capacitor than the "target" one shown in the original mod post. I asked them to please take a fresh look at the original photos provided by @kingkorg as well as a photo from a YouTube video pointing out the correct cap - to better understand what I was attempting to accomplish. The reply, after reviewing that info was as follows including a captioned photo, of the 'example mic' and, two pics of my 'donor' mic in comparison. As shown it is suggested that this mod cannot be done for reasons stated.

--In order to correctly and confidently perform the analogous mod on your mic, the schematic diagrams representing the circuitry of both mic versions would need to be referenced in order to determine where the target capacitor (presumably the capsule coupling capacitor) is located on your mic.

Unfortunately, I wasn't able to find either of the schematics (other than a hand-drawn one of unknown accuracy) after a reasonable search effort.

Please let me know how you want to proceed.<<

If you were not a DIY'er in this situation, how would You proceed?

Thanks!

 

[micolas]

Seeking some perspective on this... I asked a tech to perform the mod on a Perception 220 and as posted previously, they modified a different capacitor than the "target" one shown in the original mod post. I asked them to please take a fresh look at the original photos provided by @kingkorg as well as a photo from a YouTube video pointing out the correct cap - to better understand what I was attempting to accomplish. The reply, after reviewing that info was as follows including a captioned photo, of the 'example mic' and, two pics of my 'donor' mic in comparison. As shown it is suggested that this mod cannot be done for reasons stated.

--In order to correctly and confidently perform the analogous mod on your mic, the schematic diagrams representing the circuitry of both mic versions would need to be referenced in order to determine where the target capacitor (presumably the capsule coupling capacitor) is located on your mic.

Unfortunately, I wasn't able to find either of the schematics (other than a hand-drawn one of unknown accuracy) after a reasonable search effort.

Please let me know how you want to proceed.<<

If you were not a DIY'er in this situation, how would You proceed?

Thanks!

Incredible! All necessary and sufficient informations are available for the successful modification of all 200,220,420 models.
That technician should be doing something else. To become a politician or a lawyer.

 

[mikes425]

Incredible! All necessary and sufficient informations are available for the successful modification of all 200,220,420 models.
That technician should be doing something else. To become a politician or a lawyer.

I guess my error was to have sent a reference to a YT video where they modded a 420 vs a 220, but since i also provided reference to @kingkorg's very first post with the mod, thought that should be sufficient to illustrate. That said, is there any 'before'/'after' photo set that anyone knows of, showing this mod on a 220? Thanks!

 

[Khron]

Incredible! All necessary and sufficient informations are available for the successful modification of all 200,220,420 models.
That technician should be doing something else. To become a politician or a lawyer.

i also provided reference to @kingkorg's very first post with the mod, thought that should be sufficient to illustrate.

Yeah, that (insert chain of expletives here) really should be in an entirely different line of work, if/since he is clearly incapable of following even the simplest clearest instructions ("solder this component here"), as well as entirely unwilling to even own up to his f**k-up, and arrogant about it. I'd argue he'd even deserve to be outed here, just so others don't end up falling into the trap of his "services".

That being said, only someone legally blind would need even clearer instructions than what can be found in the initial post here.

 

[micolas]

I guess my error was to have sent a reference to a YT video where they modded a 420 vs a 220, but since i also provided reference to @kingkorg's very first post with the mod, thought that should be sufficient to illustrate. That said, is there any 'before'/'after' photo set that anyone knows of, showing this mod on a 220? Thanks!

Everything is extremely clear.
The modification can be done in 2 ways, with the same result:
1. Keep the stock capacitor of 220pF on the PCB and connect another capacitor C' in parallel. The value of the equivalent capacitor is their sum:
Cequiv=220pF+C'
2. Remove the stock capacitor from the PCB and solder another capacitor of the desired value.

All the informations and pictures are in this thread.

 

[mikes425]

Everything is extremely clear.
The modification can be done in 2 ways, with the same result:
1. Keep the stock capacitor of 220pF on the PCB and connect another capacitor C' in parallel. The value of the equivalent capacitor is their sum:
Cequiv=220pF+C'
2. Remove the stock capacitor from the PCB and solder another capacitor of the desired value.

Thanks for this, and the pix. As I say I referenced @kingkorg's initial post which did show a 220 board, specifically. (re-pasting it here for reference)...my only fear if i send this photo is that the green arrows in the photo might confuse things, since i think that applies to a different mod done by microphone-parts... however the 220 cap is clearly identified and boxed, in that photo... so i guess if i send that pic to him i should crop those out (?!!)

Again much appreciated! Hoping to resolve this without losing the mic to them since i can only guess there will be a contention that i should pay for their additional time 'researching' this. That would exceed the original cost of the mic.

 

[micolas]

Thanks for this, and the pix. As I say I referenced @kingkorg's initial post which did show a 220 board, specifically. (re-pasting it here for reference)...my only fear if i send this photo is that the green arrows in the photo might confuse things, since i think that applies to a different mod done by microphone-parts... however the 220 cap is clearly identified and boxed, in that photo... so i guess if i send that pic to him i should crop those out (?!!)

Again much appreciated! Hoping to resolve this without losing the mic to them since i can only guess there will be a contention that i should pay for their additional time 'researching' this. That would exceed the original cost of the mic.

To avoid ambiguity, I have edited the pictures
Just download the edited pictures posted by me above.
They are relevant.
Possibly send a link to post #276.
Maybe, however, the technician in question will fix the problem and make your microphone the way you wanted, at no extra cost since the mistake belongs to him.

 

[MicMaven]

If you were not a DIY'er in this situation, how would You proceed?

The technician should restore the microphone to its original configuration and return it at no cost, effectively rescinding any agreement (contract) to install the part according to your instructions. This is the least onerous and least expensive remedy.

A contract arises only when the parties agree on all essential and material provisions of the transaction. Either the technician has breached the agreement by failing to follow your instructions, or, if he is confused and does not know what he is supposed to do, there is no contract. The can be no agreement, because the technician confirms he is either or both uncertain what you want or is unable to perform as instructed, demonstrating he did not agree to all essential and material provisions of the transaction. He is entitled to payment only if he performs according to your instructions. He should do nothing if he is confused or uncertain. He should not guess or take random action. Rescission is the simplest and least expensive remedy, restoring each party to where he was before transacting. You may have an action for compensatory damages if he cannot restore the microphone to its original state.

Gratuitous Sidebar - I disagree (in good humor) with Mr. @micolas -- the technician should NOT become a lawyer as he already failed both "Contracts 101," and "Paying Attention 100" - not to mention flunking "Communications 100."

Of course that is just MY take. Your mileage may vary. / James

 

[mikes425]

Many thanks to all for your help here. The tech and I appear to have reached agreement that he modded the wrong cap. He'll replace the 220 stock cap, with the 510pF cap that he incorrectly installed elsewhere in the mike at no charge. No idea why the link to the mod thread wasn't sufficient explanation in the first place (or why a 510 cap was used vs 540 or 560 cap which i sort of suggested) but for now, just happy i will at least get the mic back.

I have a P220 on hand i may get modded with a higher value cap-or perhaps try the Microphone-Parts mod kit-but i believe i'll be farming that out to a different tech. Thanks again!