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

[forigee]

Hi Everyone,

I just bought a used AKG Perception 100 microphone. I'll do the capacitor swap from 220pF to 680pF. I'm not going to bias the jfet. I read that it's a good idea to swap the input and output cap to a quality film one as well. My question is which are those to caps exatly?

 

[Khron]

I read that it's a good idea to swap the input and output cap to a quality film one as well. My question is which are those to caps exatly?

The input cap will be the little (yellow?) ceramic soldered between the two teflon posts, on the small horizontal board. The output one is the one next to the little 3-pin transistor and the transformer.

https://www.diyaudio.com/community/threads/akg-perception-100-mic-repair.258813/ (in this photo it's marked "V475")

 

[micolas]

Hi Everyone,

I just bought a used AKG Perception 100 microphone. I'll do the capacitor swap from 220pF to 680pF. I'm not going to bias the jfet. I read that it's a good idea to swap the input and output cap to a quality film one as well. My question is which are those to caps exatly?

I don't know how much experience you have.
Do the mods one at a time, in steps, and analyze the effects of each change.
What do you hope to achieve by changing the coupling capacitor of the capsule to the jFET gate (possibly you manage to contaminate the high impedance input area) or the output capacitor?

 

[forigee]

The input cap will be the little (yellow?) ceramic soldered between the two teflon posts, on the small horizontal board. The output one is the one next to the little 3-pin transistor and the transformer.

https://www.diyaudio.com/community/threads/akg-perception-100-mic-repair.258813/ (in this photo it's marked "V475")

Is this the output cap?

Sorry but I cant find two teflon posts.

 

[forigee]

I don't know how much experience you have.
Do the mods one at a time, in steps, and analyze the effects of each change.
What do you hope to achieve by changing the coupling capacitor of the capsule to the jFET gate (possibly you manage to contaminate the high impedance input area) or the output capacitor?

I can solder. I can read schematics, but I don't know how parts work and how amplifiers etc.. function.
I hope with better quality capacitors the microphone will sound less distorted. I ask because the company doesn't send me 1 nor 10 capacitors so I want to buy all the part with one purchase. I need to know what parts do I need even in the future.

 

[micolas]

I can solder. I can read schematics, but I don't know how parts work and how amplifiers etc.. function.

Do you have a schematic of the Perception 100?

I hope with better quality capacitors the microphone will sound less distorted.

And the other capacitors in the audio path, for example between the jFET and the second transistor, don't introduce distortion?
Where did you read about changing the coupling capacitors in this microphone?
Didn't the AKG engineers who designed the Perception series want better quality, lower distortion?

 

[Khron]

Do you have a schematic of the Perception 100?

Likely the same as the 200/220, just without the pad & high-pass

 

[micolas]

Likely the same as the 200/220, just without the pad & high-pass

Well, I know that, you yourself wrote some values for certain components on the hand-drawn schematic that is circulating everywhere, including at the beginning of this thread

The questions were for @forigee , SMDs are riskier to work with.

Edit:

People don't want to read, there have been discussions about changing the capsule's coupling capacitor in this thread before, you even said a great truth on other occasions: the best coupling capacitor is the one that DOESN'T exist. I agree, when possible I connect the capsule directly to the jFET.
All my mxl2001 style microphones have the capsule directly coupled to the jFET and a DC/DC with a slightly higher polarization voltage, of course with appropriate deemphasis. They sound excellent.
And I do this with other topologies as well.

 

[forigee]

Do you have a schematic of the Perception 100?

And the other capacitors in the audio path, for example between the jFET and the second transistor, don't introduce distortion?
Where did you read about changing the coupling capacitors in this microphone?
Didn't the AKG engineers who designed the Perception series want better quality, lower distortion?

I don't have the schematic of this mic.
Yes the other capacitors do distort as well.
I read it here. I just realized "to remove input cap" and replace just the output one.
Yes they wanted to but within a certain price.

 

[micolas]

I don't have the schematic of this mic.

The schematic is here, similar to the 200/220, @Khron also said,
but without the hi-pass and sensitivity attenuation pad options:

https://groupdiy.com/threads/akg-pe...in-mod-p200-p100-p400-p420.67473/post-1193829

Yes the other capacitors do distort as well.
I read it here.

You should read the whole thread.
Not just one post.

I personally do not recommend you to do any other mods than the one described by @kingkorg
For exemple reBIAS it requires a lot of experience, the circuit is made with SMD components, you can very easily destroy the microphone.

Yes they wanted to but within a certain price.

?

 

[forigee]

The schematic is here, similar to the 200/220, @Khron also said,
but without the hi-pass and sensitivity attenuation pad options:

https://groupdiy.com/threads/akg-pe...in-mod-p200-p100-p400-p420.67473/post-1193829


You should read the whole thread.
Not just one post.

I personally do not recommend you to do any other mods than the one described by @kingkorg
For exemple reBIAS it requires a lot of experience, the circuit is made with SMD components, you can very easily destroy the microphone.

?

Thank you. I'll do just the cap swap.

 

[forigee]

Do you know guys a "similarly good" - not harsh, smooth - sounding alernative with less self noise? Rode NT1 with capsule swap or even a DIY mic?

 

[micolas]

Thank you. I'll do just the cap swap.

Input
Output

 

[forigee]

Input
Output

Thanks a lot.
I've just found another post about the cap swap. This.

 

[Paul W]

Thanks a lot.
I've just found another post about the cap swap. This.

Just for clarity, that's about the input coupling capacitor, not the simple HF deemphasis capacitor mod that that this thread was originally about, right?

Is there any actual evidence that messing with the input coupling capacitor is a good idea? Is there something wrong with that ceramic capacitor?

If so, would it be better to replace it with an NP0/C0G ceramic capacitor than to put in a polystyrene capacitor, which AIUI is more likely to be microphonic?

 

[Paul W]

Over in that other thread at that other site, regarding the input coupling capacitor, someone said

If I can't fit a Rel-Cap 630 V polystyrene film cap, a WIMA FKP-2 at 1000 volts is an excellent choice.

I don't use low voltage film caps here, too slow. Don't use 50 volt rated caps. Most condenser mics polarize the capsule at 60 volts.

Does that make any sense? Does using parts spec'd for much higher voltages than the circuit actually generates actually matter to the sound?

Is a capacitor with the same capacitance but a lower voltage rating really "too slow"?

I guess I understand the part about not using 50 volt caps where the polarization is 60 volts, although I'm not sure that's really right... is the voltage drop across that part 60 volts?

But what's with 630V or 1000V parts in a mic? Does that make any sense at all?

 

[forigee]

Just for clarity, that's about the input coupling capacitor, not the simple HF deemphasis capacitor mod that that this thread was originally about, right?

Right.

Is there any actual evidence that messing with the input coupling capacitor is a good idea? Is there something wrong with that ceramic capacitor?

No. Nothing.

 

[micolas]

@forigee
It's clear to me how much experience you have in electronics.
If you want to do esoteric, magical mods, that's your right. And risking damaging your microphone is also your right.
But try not to mention GS here again.
*****
Are you Plautus, disguised as another nickname?

 

[forigee]

@forigee
It's clear to me how much experience you have in electronics.
If you want to do esoteric, magical mods, that's your right. And risking damaging your microphone is also your right.
But try not to mention GS here again.
*****
Are you Plautus, disguised as another nickname?

I'm not anybody else you think I am. You asked me where I read about cap upgrade. Please give me a link about the rules because I don't want to feel myself guilty here. And I'm writing to you this with the maximum respect I can give to another human.

 

[micolas]

I'm not anybody else you think I am. You asked me where I read about cap upgrade. Please give me a link about the rules because I don't want to feel myself guilty here. And I'm writing to you this with the maximum respect I can give to another human.

Ok.
To the other group posters, you should comment there in those groups.
Just make sure you don't troll here.
Read this thread in its entirety and you will find the answers to all the questions you asked.