Marik
Pro Microphone Design
kojdogg said:
Wow,
Kojdogg, I am not sure what it is all about. To make things clear, I never responded to your post and it was YOU, who contacted me, first.
What is going on here?
Best regards, Mark
Wow,
Kojdogg, I am not sure what it is all about. To make things clear, I never responded to your post and it was YOU, who contacted me, first.
What is going on here?
Best regards, Mark
kojdogg
bollocks redux!
Yeah, I'm sorry, instead of saying contacting me I should have said responding to my post where I asked for someone to do this:Marik said:
Sorry for the errorMarik said:
. Best regards to you too Mark 
PhilGood
Juice box hero
Marik said:
Phil,
I saw this line:
And my message was directed to it.
Best, Mark
OK. There was obviously some confusion.
My apologies.
Phil
Marik
Pro Microphone Design
BTW, Phil,
Earlier I wrote a reply to:
But then desided it was way too serious and personal (esp. after half bottle of wine
) to post all that on a public forum, so I deleted it. Sorry 
.
Earlier I wrote a reply to:
PhilGood said:You're never here often enough Mark!
But then desided it was way too serious and personal (esp. after half bottle of wine
) to post all that on a public forum, so I deleted it. Sorry .
PhilGood
Juice box hero
Marik said:BTW, Phil,
Earlier I wrote a reply to:
But then desided it was way too serious and personal (esp. after half bottle of wine
I should follow your example. I post crazy stuff here after 3-4 glasses of scotch!
L
LDT2
LDT2
Hi Guys,
I've been reading about this mod on every forum I can find quite extensively and I finally got an Apex460 of my own.
Right off the bat I want to thank everyone who's contributed information here, because I'm one of those people who's pretty mechanical, but doesn't have a clue about how these circuits work without guidance.
I understand all the mods mentioned here, but there is something that Dave Thomas mentioned a couple times in another thread that hasn't been mentioned and unfortunately he didn't go into great detail about it. I'm hoping that someone here "in the know" (and I know there are many) could help me out.
Anyway, Dave mentions that he replaces the coupling capacitor (C8) with a larger mylar of 2.2usd (nothing new),but then he says that he "bypasses a larger value electrolytic with a faster .01ufd". In a later reply in the same thread he says, "I replace the 1ufd with a 2.2ufd and parallel it with a .01ufd". He says that this helps with transient response.
What capacitor is he talking about that parallels C8?
Could it be C6 or C7?
If anyone knows what he's talking about and can describe which cap to change to .01ufd I would greatly appreciate it.
Incidentally, I fired up the 460 and tried some mellow vocals out today and I gotta say, it does sound pretty nice. I changed the tube to an EH12AY7 and it did clean up, but I was surprised how well it sounded with the 12AX7, on MY voice. Can't wait to do the mods!!
Thanks,
Lucio
I've been reading about this mod on every forum I can find quite extensively and I finally got an Apex460 of my own.
Right off the bat I want to thank everyone who's contributed information here, because I'm one of those people who's pretty mechanical, but doesn't have a clue about how these circuits work without guidance.
I understand all the mods mentioned here, but there is something that Dave Thomas mentioned a couple times in another thread that hasn't been mentioned and unfortunately he didn't go into great detail about it. I'm hoping that someone here "in the know" (and I know there are many) could help me out.
Anyway, Dave mentions that he replaces the coupling capacitor (C8) with a larger mylar of 2.2usd (nothing new),but then he says that he "bypasses a larger value electrolytic with a faster .01ufd". In a later reply in the same thread he says, "I replace the 1ufd with a 2.2ufd and parallel it with a .01ufd". He says that this helps with transient response.
What capacitor is he talking about that parallels C8?
Could it be C6 or C7?
If anyone knows what he's talking about and can describe which cap to change to .01ufd I would greatly appreciate it.
Incidentally, I fired up the 460 and tried some mellow vocals out today and I gotta say, it does sound pretty nice. I changed the tube to an EH12AY7 and it did clean up, but I was surprised how well it sounded with the 12AX7, on MY voice. Can't wait to do the mods!!
Thanks,
Lucio
M
mbrebes
New member
What he's talking about is actually placing another capacitor across the electrolytic capacitor (in the same holes on the board). This is to compensate for the difference between the theoretical capacitor and the real-life capacitor, in this case an electrolytic. Because of the characteristics of electrolytic capacitors, they can be a bit sluggish when it comes to high frequencies. By paralleling the electrolytic with a polypropylene or mylar capacitor of a smaller value (.01 in this case) it is supposed to help it pass the higher frequencies better. Hope that answers your question.
L
LDT2
LDT2
mbrebes,
That's perfect!! I wondered if it was something like that.
But he said that he replaced the electrolytic with a mylar 2.2ufd, so would it still work to add the .01 in parallel or is it unnecessary?
I'm asking because I know that you've never mentioned doing this step in the mod, so I wondered if it was just not necessary or that maybe we missed something by not doing it.
If you say it's unnecessary then I'll just move on with my mods.
Incidentally, I've got the mic apart and can't figure out how to access the transformer. I have everything unscrewed but, how do you get the cover off? Cut the wires?!!
Thanks so much,
Lucio
That's perfect!! I wondered if it was something like that.
But he said that he replaced the electrolytic with a mylar 2.2ufd, so would it still work to add the .01 in parallel or is it unnecessary?
I'm asking because I know that you've never mentioned doing this step in the mod, so I wondered if it was just not necessary or that maybe we missed something by not doing it.
If you say it's unnecessary then I'll just move on with my mods.
Incidentally, I've got the mic apart and can't figure out how to access the transformer. I have everything unscrewed but, how do you get the cover off? Cut the wires?!!
Thanks so much,
Lucio
C
craigmorris74
New member
Unscrew the screws on the side of the transformer shield/case and the xlr plug and housing.
L
LDT2
LDT2
craigmorris74,
Thanks, I actually had those unscrewed, but remounted the boards, so I had no play in the wiring. I unscrewed everything and that gave me some slack to separate the shield and case.
I checked the capacitor/resistor values against the schematic and found some differences:
-C4 says 650v/102k instead of 1000p/630v.
-C3 says CBB22/630v/223k instead of 0.022uf/400v.
-C5 says CBB21/630v/223J instead of 0.022uf/400v.
-R6 says 51M instead of 200M.
-C7 says L52/104 instead of 0.1uf/63v.
-C9 and C10 says L62/104 instead of 0.1uf/63v. Can these be removed with stock trans?
Are these values alright or should I match the schematic?
Also, I noticed that resistors R5, R6 and R9 look like flat capacitors (tan/brown color), all others look like "regular" resistors. Is this right?
One more, is there one site that I can go to, to get the caps or maybe a popular store that I could go buy them? I'm searching on line, but they all look different. The Ansars look like electrolytics with a wire out each end. Is that what they look like?
Sorry for all the questions. I researched this quite a bit, but opening up the mic is quite different than reading about it.
I appreciate everyones help, thanks.
Lucio
Thanks, I actually had those unscrewed, but remounted the boards, so I had no play in the wiring. I unscrewed everything and that gave me some slack to separate the shield and case.
I checked the capacitor/resistor values against the schematic and found some differences:
-C4 says 650v/102k instead of 1000p/630v.
-C3 says CBB22/630v/223k instead of 0.022uf/400v.
-C5 says CBB21/630v/223J instead of 0.022uf/400v.
-R6 says 51M instead of 200M.
-C7 says L52/104 instead of 0.1uf/63v.
-C9 and C10 says L62/104 instead of 0.1uf/63v. Can these be removed with stock trans?
Are these values alright or should I match the schematic?
Also, I noticed that resistors R5, R6 and R9 look like flat capacitors (tan/brown color), all others look like "regular" resistors. Is this right?
One more, is there one site that I can go to, to get the caps or maybe a popular store that I could go buy them? I'm searching on line, but they all look different. The Ansars look like electrolytics with a wire out each end. Is that what they look like?
Sorry for all the questions. I researched this quite a bit, but opening up the mic is quite different than reading about it.
I appreciate everyones help, thanks.
Lucio
PhilGood
Juice box hero
You need to know how to read the codes.
102 means 1nF (1000pf)
223 would be 22nF (.022uF)
K is +/-10%
J is +/-5%
All the letters are tolerance codes.
There's some calculators here that will help.
http://www.electronics2000.co.uk/
The flat resistors are not capacitors. They are just a different type of resistor.
102 means 1nF (1000pf)
223 would be 22nF (.022uF)
K is +/-10%
J is +/-5%
All the letters are tolerance codes.
There's some calculators here that will help.
http://www.electronics2000.co.uk/
The flat resistors are not capacitors. They are just a different type of resistor.
M
mbrebes
New member
All the capacitors are the right value. The scheme for reading the values is that the first two numbers followed by a number representing the number of zeros. This is the value in picofarads. So, 223 is 22000pF or 22nF or 0.022mF. So you understand, 1000pF=1nF and 1000nF=1mF.LDT2 said:
You are correct, R6 should be 200Megohms. C9 and C10 are supposed to get rid of any RF in the mic. They are not really needed. C6 and C8 are the only electrolytics in the signal path, so the only ones to consider changing. All others should be fine since they are only filtering power.
I know you can get the 200M resistor from Mouser or Digikey, along with most capacitors that you want to change.
Hope that answers your questions.
L
LDT2
LDT2
Wow, you guys are great!! This explains alot and I appreciate ya'll helping me learn how to figure this stuff.
PhilGood and mbrebes, thanks for the links, I appreciate it.
I rechecked the boards in the mic and R6 is 200M, so I feel better about that. I guess flipping the mic around to see got me crossed up somehow, but everything else checked the same.
So right now C8 and C6 are the focus and there is an option to actually remove C6 also, right?
I actually found one last (I hope) possible issue;
The tube socket has a black jumper wire going from pin 7 to pin 1 where it meets a red wire coming from R2. In the schematic it looks like this should go to pin 2 (dotted line on schematic, right). Well, now that I'm looking at it, the schematic shows a separate line going to pin 1 and 7 from R2. I suppose connecting 1 to 7 does the same thing, so I just solved my own problem, wow!
But, what does the dotted line between 2 and 7 mean then?
Man, this is such a great forum. Thank you all sooo much.
Lucio
PhilGood and mbrebes, thanks for the links, I appreciate it.
I rechecked the boards in the mic and R6 is 200M, so I feel better about that. I guess flipping the mic around to see got me crossed up somehow, but everything else checked the same.
So right now C8 and C6 are the focus and there is an option to actually remove C6 also, right?
I actually found one last (I hope) possible issue;
The tube socket has a black jumper wire going from pin 7 to pin 1 where it meets a red wire coming from R2. In the schematic it looks like this should go to pin 2 (dotted line on schematic, right). Well, now that I'm looking at it, the schematic shows a separate line going to pin 1 and 7 from R2. I suppose connecting 1 to 7 does the same thing, so I just solved my own problem, wow!
But, what does the dotted line between 2 and 7 mean then?
Man, this is such a great forum. Thank you all sooo much.
Lucio
PhilGood
Juice box hero
LDT2 said:
The dotted line is/are the grid(s) of the tube, and there are two of them (you'll notice a small space between the two). Anything in the 12A*7 family is a DUAL triode tube, meaning there are two amplifiers in each tube. Look at it as a left half, and a right half. That's why when you remove the cathode follower part of the circuit you bridge pins 6,7, and 8 to ground. That way you neutralize that part of the tube. You also remove the lead to pin 5, which turns off the filament to the right side of the tube.
4 and 5 are the heaters (9 going to ground). 3 and 8 are the cathodes. 1 and 6 are the anodes. 2 and 7 are the grids.
Get it?
Last edited:
C
craigmorris74
New member
I didn't think C6 was in the signal path?
L
LDT2
LDT2
PhilGood,
That explanation was the missing link for me, thank you!!! Now I understand what's been talked about so much better.
Removing the lead from pin 5 is new to me. On my mic, pin 4 and 5 are tied together and a yellow wire runs down to the 7 pin connector. So I would just untie 4 and 5 so only 4 goes to the connector, right?
Then 6, 7 and 8 need to be tied together to 9 which is ground.
C8 is supposed to be connected to the junction of pin 1 and R2, so would connecting C8 to pin 1 work for this, seeing that R2 runs to pin 1?
Then R8 is removed and that finishes removing the cathode follower circuit, right?
One more question if I can, is it alright to remove C9 and C10 with the original trans in place or do I need to put the cinemag in 1st?
Much thanks again,
Lucio
That explanation was the missing link for me, thank you!!! Now I understand what's been talked about so much better.
Removing the lead from pin 5 is new to me. On my mic, pin 4 and 5 are tied together and a yellow wire runs down to the 7 pin connector. So I would just untie 4 and 5 so only 4 goes to the connector, right?
Then 6, 7 and 8 need to be tied together to 9 which is ground.
C8 is supposed to be connected to the junction of pin 1 and R2, so would connecting C8 to pin 1 work for this, seeing that R2 runs to pin 1?
Then R8 is removed and that finishes removing the cathode follower circuit, right?
One more question if I can, is it alright to remove C9 and C10 with the original trans in place or do I need to put the cinemag in 1st?
Much thanks again,
Lucio
PhilGood
Juice box hero
LDT2 said:
You can remove C9 and C10 just fine with the stock transformer. The Cinemag is just an upgrade. It doesn't require the wiring to be any different, so it works for both transformers.
PhilGood
Juice box hero
craigmorris74 said:
It's not!
M
mbrebes
New member
C6 can be considered to be in the signal path, since it directly responds to the signal path passing through the tube circuit. If you put an oscilloscope on the cathode, you would see the signal that is being fed to the grid. The cathode resistor sets the DC offset of the tube stage, to try to get positive and negative clipping to occur at the same time. Unfortunately, it also lowers the gain of the stage. The capacitor (C6) brings back the gain by passing all the higher frequencies.
L
LDT2
LDT2
Hi guys, me again.
What would be the closest thing to the now defunct Black Gate capacitors? I want to get the closest thing I can find.
Also, do you all use the Ansar cap for C8 or Mylar?
Mylar, being metalized film or polyester/foil, radial, axial or what? There seem to be many different kinds.
I know you're probably sick of me by now, but every time I think that I finally have all the info I need to do this mod, I hit another stumbling block.
Thanks,
Lucio
What would be the closest thing to the now defunct Black Gate capacitors? I want to get the closest thing I can find.
Also, do you all use the Ansar cap for C8 or Mylar?
Mylar, being metalized film or polyester/foil, radial, axial or what? There seem to be many different kinds.
I know you're probably sick of me by now, but every time I think that I finally have all the info I need to do this mod, I hit another stumbling block.
Thanks,
Lucio