MPCNYC,

Did I say that the mic will sound better with B+ = 120 volts... ? Honnestly, I really have no idea, how could I know ? I haven't started the mod yet... you're so right !

Every body (you, Klaus,...) keep telling me I've got to listen... I WILL, BUT I'm not "there" yet !

Again, I just wanna understand what's happening "theoriticaly" in this microphone.
Listening won't highlight me a lot about what's going on "electrically".

If by your experimentations you arrived at the conclusion that you got the best sonically results (I don't deny it) with a certain value of B+, very well.

If the Lucio's Apex 460-C12 version sounds really great (I don't deny it) even with the fact I think the polarization voltage he wrote on its schematic is no correct. Very well.

The goal is to have a gound sounding mic. I do agree.

My goal is not only to have a great sounding mic. My goal is to learn too.

So, when I'll mod my microphone and I'll realize I've got better result with a certain value of B+, or C8, or R10, my ears will be the only judges BUT I'll want to know what the real voltage I'll have at the capsule, I will want to make the calculations and find out at wich frequencies the filters cut in the circuit. Why ? Because I'm curious, because I like the maths...

We're playing with high voltages and expensive components here. According to me, it's important to have at least a good idea of what's is going on. I don't feel like exploding a $200 capsule, magnetizing the output transformer or decreasing dramatically the like of the tube, that's all.

You know, I'm not denying the sonic results of your experimentations, I'm just trying to understand them. That's all. Don't take it in the bad way... Be assured, I'll will questionning the results of my experimentations too !

Maybe we don't have to same approach, or the same curiosity.

Maybe I'm not asking my questions in the good place...

I've explained why I'm pretty sure Lucio got its polarization voltage measurement wrong.

You got the same results with an electrostatic meter ? Well I don't know what to say...
We are the two last one left in this discussion.
I'm sorry but will need more than your word on that one... I will need "the how" and "the why"...

eD

When did I ever say that my measurement was the polarization voltage?

All it is IS the voltage measurement at THAT point in the circuit. It's NOT WRONG if that's what was measured at that point.

Look, get whatever results you want, but don't say I'm WRONG because that IS what was measured at that point in the circuit. I just posted MY results with MY mods.

Personally I could care less about the theory behind it. That's for the guys that design these things. I just followed the schematics that AKG designed. Why don't you argue with them, who incidentally used analog meters when they built these mics.

Read my previous thread in regards to you "blowing up a $200 capsule.

Lucio

quote:

Originally posted by LDT2:

quote:

Originally posted by vertiges:
The original AKG value for B+ is 120 volts... Are you telling me that a jump of 34 volts won't make any difference to the voltage polarization of the capsule ?

Under the right conditions, yes.

Which ones ?

quote:

Originally posted by LDT2:
The reason why people were originally dropping the voltage from the PS had nothing to do with fears of dammage.

That's what I did understood.
And I can't talk about the effects on the sound as I haven't tried it.

quote:

Originally posted by LDT2:
If you go back and read the post from Dave Thomas in the "Interesting read on the Apex 460" thread that you quoted him saying that the AKG schemo had 61v writen for the capsule, he also said that "the Peluso capsules can stand nearly 80v..." where the stock capsules can only stand 60v before the diaphragm gets pulled into the back plate, so it's set to 55v stock. Which is probably the reason for the 1G resistor and R5. Also R3 & R4 are a lower value than the original used, thus the need for more resistance.

Yes I'm aware about the thread of D.T. Actually, that have been bugging me since the beginning...

I will verify, but I think I read that some people used a CEK12 in a Gyraf G7 circuitry which gives 80 volts at the capsule.

It's good you mentioned it... If we follow "my theory", with B+ = 182 volts, the chinese capsule receives 91 volts of polarization and survives ???
I'm aware of that too... I just can't find anywhere if it's true or wrong...
[/QUOTE]

quote:

Originally posted by LDT2:
Plus, if I only have 62v to 64v measured before R10, then I'm more than safe with voltages. The recommended 60v to 64v from Peluso is for optimum SOUND. Your not in trouble until you get beyond 80v which isn't possible if there's only 64v going into R10.

I think you misunderstood the way I talked about safety... English is not my first language, maybe I didn't explain myself very well. I didn't mean the voltage has to be decreased for safety reasons...

R10 and R5 doesn't influence the polarization voltage... There is no DC voltage drop accross R10.

quote:

Originally posted by LDT2:
We adjust the input voltage to tune the SOUND of the mic because more brightens the sound and less initially was used to calm the harshness in mics that weren't modified to the extent of mine or Michael's. I chose to get as close to AKG's spec's because it was safe as they've already proven that it works. The 120v at B+ would just soften the highs a bit more as well as gain slightly. We decided that we liked a bit more brightness and gain in our mics.

I understand very well...
And, again, I can't talk about how the mic sound with a B+ of 120 Volts.
I just doubt about the real polarization voltage you get at the capsule... BTW, do you know the internal resistance of the voltmeter you used ?

quote:

Originally posted by LDT2:
Bottom line, I can appreciate your concern and desire to understand the reasoning behind the circuits, but there's more than enough "cushion" in voltage to prevent any damage. Especially if you consider that my stock Nady had 182v coming into B+ and the stock capsule, which can only withstand 60v max, survived.
Lucio

Is there anyone else (besides D.T) who talked about the max voltage a chinese capsule can handle ? I've been searching a lot...

eD

quote:

Originally posted by vertiges:

I just doubt about the real polarization voltage you get at the capsule... BTW, do you know the internal resistance of the voltmeter you used ?

If you read my last post you'll see that I never said it was the polarization voltage, it's simply the voltage at that point in the circuit.

OK if R5 and R10 don't effect the voltage, then my measurements would be correct. This going in circles and quite honestly I have other things to do.

Lucio

quote:

Originally posted by LDT2:
When did I ever say that my measurement was the polarization voltage?

There is no other drop of DC voltage after the junction of R3 and R4... The voltage you get at the junction of those resistors is the polarization voltage.

quote:

Originally posted by LDT2:
All it is IS the voltage measurement at THAT point in the circuit. It's NOT WRONG if that's what was measured at that point.

A traditional meter can't measure it with accuracy ! I explained why in detail...
But I believe you when you tell me that's what you read on your voltmeter... It wasn't just the right tool...

quote:

Originally posted by LDT2:
Look, get whatever results you want, but don't say I'm WRONG because that IS what was measured at that point in the circuit. I just posted MY results with MY mods.

Again I'm not arguing about any sonical aspects of your mod... I'm talking about only the voltage polarization value.

In a scientific point of view, it's A FACT the polarization voltage cannot be measured the way you did it...

Don't you care about the fact the voltages you posted might be wrong ?
I do care about the fact I might be wrong since the beginning of this discussion... That's why I keep searching...

eD

...also in talking with Peluso the reading voltage should take place before the high value resistors...

BTW, nowhere in the 25 pages of this thread has anyone (to my recollection) blown up a mic or any associated parts. Perhaps you should take comfort in that.

Ok

Lucio and MPCNYC... Michael ? Is that your name...?

I propose "we take a break".

I will do my homework and try to find all the informations about my "polarization voltage obsession"

I'm gonna try to find out how much voltage a chinese voltage and the CEK12 can handle as well...

Best regards,

eD

If anything you need to brush up on your English, because you're obviously not understanding what we're saying.

I'm not questioning your theory or the "proper" way to measure capsule polarization, I am simply saying that it measured 62v just before R10, period.

Whether or not that is the actual polarization voltage doesn't matter to what we're trying to explain to you. If John Peluso said that measuring the voltage before R10 is sufficient then that's good enough for me, again.

Trust me, you studying more theory on this is not going to help this discussion.

Do they have schools for this stuff where you are?

I dare say McGill would qualify

Language barriers always cause frustration. Sometimes how 'grammar' translates from one language to the other can come off very offensive or in a manner that was not intended. I'm certain this is the case here.

lets continue is thread in russian, german or french if you like !


btw I found the words on multimeter resistance giving you false results very interesting. It gives us now the possibility to measure precise (if we know the meters resistance) ...pretty interesting


nicholas

quote:

Originally posted by redlir:
I dare say McGill would qualify

Language barriers always cause frustration. Sometimes how 'grammar' translates from one language to the other can come off very offensive or in a manner that was not intended. I'm certain this is the case here.

Amen to that...

quote:

Originally posted by nb:
lets continue is thread in russian, german or french if you like !

No problem with the French... In Russian or German :

quote:

Originally posted by nb:
btw I found the words on multimeter resistance giving you false results very interesting. It gives us now the possibility to measure precise (if we know the meters resistance) ...pretty interesting
nicholas

Yes inded, it's very interesting.

The internal resistance is often given in the manual of you multimeter under "specifications".

The good thing when the discussions becomes "intense" is : that forces me to question myself and to "dig deeper". That pushed me to make the calculations and to remake the measurement with my old "low internal resistance meter".

There were 13 volts of difference between the two voltmeters...

eD

Wow, just got through wading through this mutha of a topic...

I want to get as close to C12 as I can, so I'm going to use the TAB BV314 trannie, the 460 mic (since that's the only one that the TAB will fit into), the Peluso CEK-12 cap and as much of Lucio's schematic as possible.

MPCNYC, you talked about the influence of the grille and that you had built your own...any tips? I'm not too mechanically inclined, so I may just remove the first mesh layer out of the 460. Also, you mentioned having a photo of stuffing the BV314 in the 460, could you email me a copy so I can see how it fits?

I'm not too swift with the soldering iron, so I may just grab all the parts and have Dave Thomas do the circuit board soldering since his shop is nearby (I'm also in Vancouver).

One other question: I saw one person buffed his mic casing to a shine, anybody else do anything cool to pimp their modded mics? I was thinking of painting it or something...anything so the voice talent isn't staring at the word "Apex" for hours at a time...

Cheers,
Michael

Michael,

For reference, here is a pic of the grill of the real C12.



There are someone who painted the body in this thread.
I think D.T. paint them to or he just add a sticker ? I'm no sure.

eD

There is a part in the thread about me talking about building the grill. I can amplify on it more if you've got questions. You can get the grill material from smallparts.com.

And boy it is a bit of a pain to make! I did two of them for the 2 460's I did. I'll take a couple of pics. I'm going to the studio today and I'll bring those mics home. The main issue is if you put the CEK12 with associated mount in a 460 the top of the capsule seems sort of too close the top of the grill. Secondly, the mesh on a C12 is a bit thicker than the 460. and I found the it sounds quite different with the thicker mesh. more open....less comb filtery. It's a subtle but noticeable improvement.

I've painted all the mics I've done. I forgot the paint I used but I've got the can somewhere...it looked cool.

quote:

Originally posted by MPCNYC:
The main issue is if you put the CEK12 with associated mount in a 460 the top of the capsule seems sort of too close the top of the grill.

I imagine there is no way to reduce the height of this thing without destroying it ? :



I haven't had it in my hands yet, so I've no idea.

You made me realise that the grill of the C12VR is different than the one from the original C12.
There is a second ring on the mesh "above" the capsule (like in the 460).

This is the C12VR :

quote:

Originally posted by MPCNYC:
I've painted all the mics I've done. I forgot the paint I used but I've got the can somewhere...it looked cool.

By the way, did you use a primer or something like that ?
Did you sand it before ?
I've paint a lot of rack front panels and It has been difficult to make the paint stick correctely.
I used "metal car paint". I've tried different type and brands.
But it's maybe because the front panels are anodised aluminium.

Thank you,

eD

No....to lower height you must destroy! Well, you could probably get a really sharp blade and sort of cut out about 1/8 inch or so and re-epoxy the the mount together. If you use the right stuff and do it carefully that will work.

I removed all the innner mesh from the 460 and it still sound a little odd to me. The mesh on C12 is bigger and is not like the C12 VR, like you said.

I would sand it slightly, with very fine grit 600 or 800 just to kind of set it up for spray painting. Then clean it with some alcohol so no solvents are left on the mic. Then just use good spray paint technique. I used Rustoleum "hammered" both the Silver and Dark Bronze look good. If you paint it right you can also obscure the "NADY" well...I've used epoxy filler first to fill the logo, I bet bondo (for auto repairs) would be even beter and easier, and then sand. If you were really wild you could get it electroplated...nickel would look sweet!!

I post some pics tonight or tomorrow.

Michael

Michael,

Thank you for all the infos.
I haven't thought about hammered paint, it's a very good idea.

I'm curious to see the pics.

eD

BTW...there's a pic of the head basket I rebuilt on page 10 of the thread.

quote:

Originally posted by MPCNYC:
There is a part in the thread about me talking about building the grill. I can amplify on it more if you've got questions. You can get the grill material from smallparts.com.

Yes, looked at the picture, any help you can give would be appreciated. I assume you tore out all the mesh from the 460 and then soldered in the new mesh...how did you get the "mushroom" top to curve? And which mesh specifically did you use? (there were several types on smallparts.com). I'm guessing it was a bit of trial and error to get it to fit. Did it stay in place easily while you soldered it in?


One other question for everyone. In an old Mix article on vintage mics Stephen Paul, the late mic guru, said:

"AKG designed the C-12, identical to the C-2 in every way except for its 6072 industrial triode. This is an internationally available miniature twin triode tube and was still used much later in AKG's The Tube microphone. However, when we restore or modify C-12s or 251s at Stephen Paul Audio, we equip the microphones with a 5751, a tube we have found to have preferable sonic characteristics—it is extremely quiet and consistent."

Anybody try a 5751 in the 460? It's a 12AX7 pinout, but with a lower mu (70 instead of 100).