Sela T-12 inspired Mic... PSU/Transformer help!

[speakercoil]

Yeah that's one of the things I was wondering about. I was going off a schematic that didn't have any connection points indicated, so I wasn't sure where the connection was made... If it was right before R6 or if it was on both R5 and R6. Like I said I am a novice at theory so I wasn't sure which was correct. So I am assuming now just connect it to R6 then?

Assuming that is correct here is my moded schematic... With new values and the removal of 5 and 6 in parallel.

Let me know what else should be changed. I didn't add another resistor to ground as proposed, because I am not 100% sure where to put it in the signal path, or what value to use!

-Grant

 

[hazmatstrat]

Yeah that's one of the things I was wondering about. I was going off a schematic that didn't have any connection points indicated, so I wasn't sure where the connection was made... If it was right before R6 or if it was on both R5 and R6. Like I said I am a novice at theory so I wasn't sure which was correct. So I am assuming now just connect it to R6 then?

Assuming that is correct here is my moded schematic... With new values and the removal of 5 and 6 in parallel.

Let me know what else should be changed. I didn't add another resistor to ground as proposed, because I am not 100% sure where to put it in the signal path, or what value to use!

-Grant

Hi Grant,

If you raise the voltage to 125v, rotate R6 90*, make R6 10k then you have the added filtering on the entire circuit vs just the plate voltage. The grid to ground is from the capsule/grid connection to ground 680m to 1 gig.

Jim Jacobsen
JJ Audio

 

[speakercoil]

OK... So maybe this will be the final draft... ::fingers crossed::

So I think this is what you were talking about. I believe it is correct!

It would be a amazing to find out this is a good to go schematic!

Note: I added the resistor so now all Resistors have been renumbered... Though I should probably make R6 and R7 labeled reversed from one another in terms of the circuit, but oh well... When I realized that I was too tired to change it back!

Thank you so much for all the help so far. There is no way I could have gotten this far without the help!

-Grant

 

[hazmatstrat]

OK... So maybe this will be the final draft... ::fingers crossed::

So I think this is what you were talking about. I believe it is correct!

It would be a amazing to find out this is a good to go schematic!

Note: I added the resistor so now all Resistors have been renumbered... Though I should probably make R6 and R7 labeled reversed from one another in terms of the circuit, but oh well... When I realized that I was too tired to change it back!

Thank you so much for all the help so far. There is no way I could have gotten this far without the help!

-Grant

Nice try!

120v-R7_C3_connection to plate R6

JJ

 

[speakercoil]

Ok... I thought you had said raise it to 125 volts, but there you said 120. So I dropped it back down.

I think I made the proper change this time!

-grant

 

[speakercoil]

or wait wait wait... R7 should be before it goes down to C3...

 

[speakercoil]

So like this!?!?!?!  ???

 

[hazmatstrat]

So like this!?!?!?!  ???

Bingo, Bam, Yahoooooo

125v Yes

Now for the pattern control for the unused side of that M7  ???

Enjoy
JJ

 

[rodabod]

What body are you putting this in? Just trying to keep things in perspective.

Roddy

 

[speakercoil]

I am putting this inside a Beesneez Body... The bigger one (can't remember the size). It's about U47 size so I figure it should all fit in there being that is a pretty damn big mic.

OIY... Pattern Selecting... I bet that is a whole other circuit to add into the mix isn't it? I think for the first run, leaving it in cardioid is fine for now. If that tests well and works to spec, then maybe I will look at adding pattern selecting in a second go at it!

-Grant

 

[speakercoil]

http://www.beesneezmicrophones.com.au/store/index.php?_a=viewProd&productId=47

That's it right there... The 60mm

 

[rodabod]

Cool. You can always convert to a U47-style circuit later.

 

[speakercoil]

OK... So final question...

Trying to source out a pre-designed PSU that provides 125v... I'd rather not use the Chinese ones, but worse comes to worse I will. I think they put out 125 or 120 or something. I checked the one originally used on Sela's (it was a Neumann of some sort), but it doesn't pump enough voltage from my research. Also the G7 one is like 160v or something weird, and finally the U47 is something like 105v. So I am still looking for a decent design for this sucker... Any suggestions?

-Grant

 

[strangeandbouncy]

HI,


  I am sure I have already said this! - Saturn Sound, But I'd just go Chinese. its a psu, it gives you what you need.  end of.




      Kindest regards,\




      ANdyP

 

[Gus]

V2 looks like what I posted about.  Now go find the Royer 2001 mod and look close.  You might even want to look at the power supply schematic.

I suggest you google/find book(s) , Ohms law, Kirchhoff, Norton. 

 

[speakercoil]

Yeah everyone always says saturn sound... The problem is getting in touch. I've tried contacting several times, but never with any luck! Trust me I would like nothing more than to go the easy way out. I have thought about the chinese power supply, and I may use that just to test the mic to make sure it works and to save money early on and get to use it sooner. However in the long run I feel it would best suit the time spent hammering out the design, sourcing the parts, and ultimately building the thing to actually find a nice power supply unit for it or build one!

-Grant

PS: Gus... V2? So now I am confused... In your opinion would V2 or the final version be the best? lol... I mean I am sure a lot of it is just preference among designers, but out of curiosity do you think V2 would be a pretty choice?

 

[speakercoil]

Oh for all interested I finally found a high quality resistor in the 1g range...

http://www.ohmite.com/cgi-bin/showpage.cgi?product=supermox



-Grant

 

[zebra50]

I'm guessing those are big (37 mm!) and expensive. There's (almost) no current flowing through that resistor so you don't need a high power device.

 

[rodabod]

Also, you may not need to go so high as 1G. ~500M may suffice.

Going back to what Gus was saying, this is a very standard circuit (though not in any way inferior). What probably really makes the Sela mics stand out will be the quality of their capsules.

 

[hazmatstrat]

OK... So final question...

Trying to source out a pre-designed PSU that provides 125v... I'd rather not use the Chinese ones, but worse comes to worse I will. I think they put out 125 or 120 or something. I checked the one originally used on Sela's (it was a Neumann of some sort), but it doesn't pump enough voltage from my research. Also the G7 one is like 160v or something weird, and finally the U47 is something like 105v. So I am still looking for a decent design for this sucker... Any suggestions?

-Grant

Hi Grant,

Go with the Apex style 9 pattern supply, rebuild it with good caps, use 1-60v and 1 64v zener diode,  and look at the 460 schematic for the pattern circuit. One resistor one cap. Or the MK7 circuit 2 resistors 1 cap.

Jim Jacobsen
JJ Audio