Apex 460 mod - Tim Campbell's capsule

[saxmonster]

It's going to be more like an ELA M circuit but it'll sound good with Tim's capsule, it's amazing capsule. But you have to modify the PSU to provide for 55-60V polarization voltage (which means 110-120V B+). Learned that the "hard way" myself. You'll find means to do that searching here. Changing R7 to 1.8K (ELA M value)  starts to make sense also with 110 B+. All the capacitor swaps may not be necessary. When you get the mic check first what's in there, stock parts might be fine, they've changed through the years.

What happen with the "hard way" Did you ruined a capsule?

I am getting one of Tim's capsule and my pins 1 & 4 on the stock apex 460 PS are reading 143vdc.  I am going to swap out the zeners and lower it to 120-125vdc.  Is this a safe range? What happens if its a little hotter or below 120vdc?

Thanks
-Scott

 

[pasarski]

It's going to be more like an ELA M circuit but it'll sound good with Tim's capsule, it's amazing capsule. But you have to modify the PSU to provide for 55-60V polarization voltage (which means 110-120V B+). Learned that the "hard way" myself. You'll find means to do that searching here. Changing R7 to 1.8K (ELA M value)  starts to make sense also with 110 B+. All the capacitor swaps may not be necessary. When you get the mic check first what's in there, stock parts might be fine, they've changed through the years.

What happen with the "hard way" Did you ruined a capsule?

I am getting one of Tim's capsule and my pins 1 & 4 on the stock apex 460 PS are reading 143vdc.  I am going to swap out the zeners and lower it to 120-125vdc.  Is this a safe range? What happens if its a little hotter or below 120vdc?

Thanks
-Scott

I almost ruined the capsule by polarizing it too high (65 and also 70 volts for couple of sessions).  I sent it to Tim for inspection and if I understand right the voltage when the membrane stuck's to the backplate had gone little lower from the stock value but the capsule was still fine otherwise. He also adjusted the tone of the capsule because I wanted it a little brighter, and all this for free, great service. He said he normally doesn't warranty his capsules if polarized over 60 volts.

 

[saxmonster]

Quote from: saxmonster on May 14, 2012, 07:15:29 pm
Ok so I did some testing on the apex 460 power supply today after work.

So zener 5 = 69.5vdc
    zener 6 = 71.6vdc

which = 141.1vdc so why is it that when i measure pin 1 i get 142.9 and not 141.1vdc.

For pin 1 its 142.9 VDC so I definetly need to get new zeners as this is 22vdc over what it should be, by why doesn't it equal 141.1vdc with the two zeners added together?

Pin 2 = 6.63 which is great for the heater right?

pin 3 starting from omni to figure 8 goes like this

0.010vdc ---- Keeps dropping for some reason
15.45vdc
30.6vdc
45.6vdc
60.6vdc
75.9vdc
91.2vdc
106.5vdc
123.5vdc  ----- Keeps rising for some reason.


Do theses look good?  Now if I put lower zeners in will they affect the numbers for polarity patterns?

Pin 5 = .053
Pin 6 = .04

I think these pins are for the transformer?

I did all this with just the PS turned on and the cable attached.  No mic attached on it.

Tim's Capsule is on its way so I need to start modding this mic and getting it ready.

Can't wait.

-Scott

So i put in a new 39 vdc zener which actually reads 38 and now between pins 1 & 4 i am getting 110.8 VDC.  I am going keep that value as it is close to a elam 251.  Now my heater is still at 6.63 at pins 2 & 4.  But now all the polar pattern values have changed how do these look?



pin 3 starting from omni to figure 8 goes like this

0.010vdc
12.02vdc
23.85vdc
35.5vdc
47.2vdc
58.9vdc
71vdc
83.5vdc
96.5vdc

How do these values look?  I am still waiting for the bv11 transformer.  I was hoping to do a lot of work this weekend on it.  But i think i will wait for the transformer.  Tim's capsule is hear and looks great.  No mic was hooked up these are just reading from the power supply only.  No cable or mic connected.

Should i shoot for 120vdc at B+ not 110?  I just want to ruined the capsule.

-Scott