Perception 200 Polarization Voltage

[Khron]

Then again, there's the "catch" one should be aware of, when measuring said voltage - i've read that the "standard" 1Meg impedance of most voltmeteres can and does load down that voltage.

http://groupdiy.com/index.php?topic=3508.msg42654#msg42654 and the next post of microx.

 

[gary o]

But we can measure before the high impedence & predict via the maths at which I am no good

 

[Marik]

To me it seems like a U87 circuit especially since my polarization voltage is 46V if it were a Ai it seems the DC coupler circuit would be populated and I would have around 60V It's there just not populated.

The U87 doesn't have emitter follower and EQ section in the Perception doesn't do what it supposed to, so I am wondering where is similarity, let alone The schematic on it is the same as the Vintage U87 as you write earlier?

Best, M

 

[JessJackson]

its not…

its exactly a u87ai circuit and even makes use of the wasted u89 pads which lead everyone to believe it was a exact clone of the circuit with no additional consideration other than modifying to use smd's

I ordered one to switch out capsule, coupling cap and filter caps. worth a try.

J

 

[gary o]

its not…

its exactly a u87ai circuit and even makes use of the wasted u89 pads which lead everyone to believe it was a exact clone of the circuit with no additional consideration other than modifying to use smd's

I ordered one to switch out capsule, coupling cap and filter caps. worth a try.

J

Interesting mic for DIY if it does have that circuit would like to know the voltages around the 2N3819

What are the U89 pads ?

Thanks

 

[Marik]

its not…

its exactly a u87ai circuit...

I am not sure if you never analyzed those circuits, or just repeat what others say... For starters, please consult Perception and original U87ai schematics  (for your convenience I post them here) and tell if to your eye they look exactly the same... While you are on that please look at the jFET gain in the Perception and then in original U87--this should give you a good idea as for the EQ de-emphasis part efficiency (one of the reasons some think there is no de-emphasis here. With closer inspection, they actually might find one). After that we can resume.

Thanks, M

Perception input board:

Perception output board:

 

[Aaronrash]

Since I don't know much about U87 circuits so I'm not sure but I can say that taking out the .47uf cap between the 1M resistor and FET changed the high frequency response drastically. At the cost of more hiss in the signal.

A U47 type capsule is not appropriate for this kind of mic in my experience so far. I'm gonna put a high end K67 inside of it, replace the FETs and .47 cap and call it a day with this mic.


I'm gonna put my RK-7 in the new MXL990B kit from microphone parts witch will be a perfect fit for that capsule and with the benefit of the new implemented polarization voltage trimmer so I can try different voltages etc...

 

[JessJackson]

its not…

its exactly a u87ai circuit...

I am not sure if you never analyzed those circuits, or just repeat what others say...

I'm not sure if you trace your own circuits or just repeat what others do…

for everyone reading here is the original online document http://www.audioimprov.com/AudioImprov/Mics/Entries/2013/2/26_AKG_Perception_220.html but he states there are mistakes and unknowns in his trace.

I ordered one and it should be here in a couple of days so i'll trace it myself.

cheers four your input

J

 

[pasarski]

its not…

its exactly a u87ai circuit...

I am not sure if you never analyzed those circuits, or just repeat what others say...

I'm not sure if you trace your own circuits or just repeat what others do…

for everyone reading here is the original online document http://www.audioimprov.com/AudioImprov/Mics/Entries/2013/2/26_AKG_Perception_220.html but he states there are mistakes and unknowns in his trace.

I ordered one and it should be here in a couple of days so i'll trace it myself.

cheers four your input

J

I think that there was one "it's" too many that may have caused a misunderstanding. You prolly ment to say " It's not exactly a U87ai" circuit? Because obviously it's not, but there's some "similarity" (like the article also say's).

 

[gary o]

Jessjackson did you get  couple of these in the end......... Im thinking of getting one,Im still a little confused as to what is inside but I think its U87 front end emitter follower & 2:1 transformer & is the DC DC part operational .....I was thinking of swaping transformer for 10:1 adding U87/KM84 circuit on perf board & utilizing the DC DC converter.... wonder how bad capsule is ....

& I read the mic sounds good as is .....cheap enough ....