Apex 460 capacitor change?

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EdgeGuy

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I just recived the Apex 460 and did a test recording with the stock tube and a Telefunken 12ax7 smooth plate.
The difference is not small. The mic sounded brittle, peaky, and noisey with the stock tube and with the Tele the noise floor fell, and the sound is very smooth. I am happy with it.
My question is - what capacitors in the mic should I replace? Where are they? What values? etc.
I don't understand scamatics. I can't even spell it. But Im good with a soldering iron.

Thanks.
 
The ones I replaced are marked C1, C2, and C8. They are all 1uF. I used 1uF 250v mylar capacitors. Watch out, they are pretty big!

It can be tricky! There is not a lot of room and you'll need to bend the leads around so that the caps can lie flat, don't touch other leads and the case can still go back on.

I also used a Telefunken for replacing the tube, except I used a 12AT7 instead. I tried a 12AY7 also, but went back and forth until I decided the 12AT7 sounded best.

I've done so many changes to this mic I don't remember how it sounded originally and I don't use it much. I thought I would! I used it for some backing vocals once and thought it sounded fantastic.

I have aquired mics that I use more often, but I'll have to use the modded one in a session again and see how it now compares to the better mics I have.

Don't really know why I lost interest.
 
EdgeGuy said:
I just recived the Apex 460 and did a test recording with the stock tube and a Telefunken 12ax7 smooth plate.
The difference is not small. The mic sounded brittle, peaky, and noisey with the stock tube and with the Tele the noise floor fell, and the sound is very smooth. I am happy with it.
My question is - what capacitors in the mic should I replace? Where are they? What values? etc.
I don't understand scamatics. I can't even spell it. But Im good with a soldering iron.

Thanks.
Click to expand...

Just rented one myself for the weekend...Found it nice over all...but i did rip into it.......will buy one and do some mods on it when i get it.

I also used a 415 from apex which i found was nice sounding for the rap vocals I helped a friend record at my place.... would probaly mod it to.

there not bad mics for the dollar as is :D

I was overall impressed :D
 
Geeeeez this is an ugly looking circuit!

I may have to attempt to rebuild as a C12 circuit!

Looks like the only real cap that needs changing is actually C8.
 
C8 it is

That's what I thought. :rolleyes:
C8

An ugly schematic?
That reminds me of a joke involving camels.
I wouldn't know.

I think I read elsewhere that in order to rebuild to C12 spec. you need to upgrade the transformer.
 
new question

C8 is a 1uf 450v cap.

Is 450v really going through it?
Can I use a different cap?
Am I mad?

Thanks
 
No, you can use a 250V. The power supply is putting out about 200v without a load. Once under load the working voltage is more like 125. I can measure it with a voltmeter to be sure.
 
Huge CAPS!!!

Sorry.
I am looking for a high quality cap and all I find are HUGE Caps. ie: 1" by 2".
This won't fit in the mic.
Am I looking at the wrong type of cap?

What should I look for?
 
Look for an NTE Mylar/film capacitor. 1.0MFD 250V. The model is MLR105K250

It should be about 1/4"x5/8"x3/4" in size.
 
PhilGood said:
I may have to attempt to rebuild as a C12 circuit!
Click to expand...

The C12 has quite elaborate tube biasing. One half of C24 is much simpler and resembles input stage of the 460.

The 460 schematics is the same as Nady 1050. I have posted about later somewhere here, analysing why the designers were forced to use such... non-orthodox solutions and also posted listening impressions of the mod.

To make the circuit looking more like C24 is quite easy:
Remove R8
Cut traces from tube pins 6,7,8 and short them together
Connect C8 to juncion of pin 1 and R2
For the transformer use a high quality 1:8-1:10 Lundahl or Cinemag (depending on your taste).

For upgrading, besides aforementioned C8:

Ceramic C4 replace with polystirene cap of the same value with at least 150V rating.
You also can experiment with removing local NFB C6 cap, or replacing it with Black Gate cap of the same value.

You could as well to get rid of C9-C10.
 
All day session w/ 460

I have most of my mics out on loan including my Earthworks.
All I had was an Oktava 319 , 012 and the Apex 460.
Recorded a Female vocalest who always sounded best on the 319.
O.K. I used the 460 (because I wanted to learn it) and found a setting somewhere between C & Omni.

The closer I switched toward Omni the brighter it got but not in a useful way.
I backed off and the mic got so smooth.
The mic was so smooth that I had to add the correct EQ to bring out some presence. The first time I ever EQed her.

This is in contrast to what others have said about this mic being overly bright in general. I wanted it more present.
I do have a new 460 with the "matching" shockmount in case they changed anything else.

Still later in the day I recorded sax and trumpet and got the best horn sound -for me- ever. I usually use the Earthworks for this with great results.
Not anymore.

The mic is not transparent. I want to make it so.
That is this mic's problem.
Question, does this mic use negitave feedback?
If so is there a way to decrease the amount?
Was that a stupid question?

Thanks.

P.S. Im getting another one because they are so damm fun ,cheap and sometimes wonderful sounding.
 
Marik said:
The C12 has quite elaborate tube biasing.
Click to expand...

Mark, if I were to rebuild as a C12, I would follow the ENTIRE schematic! Power supply included! The 460 would just end up just being a shell. The Elam 250 clones I built are working EXTREMELY well and I have full confidence in reproducing an AKG circuit! Yeah, the capsules aren't the same, but the amps these guys designed...WOW!! They make even the chinese capsules sound good!

Did the same with a Sony C800G clone and I took out the peltier element. Smoothest mic I have now. Blows doors on the Red bottle mic I have. No problems with it overheating at all! Plus, there is an unreal midrange fullness! It cuts and sits well above the mix!

I am starting to think the 6AU6 tube offers most, if not all the depth and warmth of a VF14 or EF14 since as pentodes the geometry is very similar. Maybe biased differently, but the results are pretty spectacular. Of course you have to get the B+ voltage up to 230v, but I can't believe the spectrum I am getting with 797 3 micron 1.1" capsules as well as a Nady 3 micron 1". That seems to be the biggest effect as a 6 micron doesn't exhibit the same smoothness. 6 micron capsules almost sound grainy! Oh, and for the test I am using an off the shelf $7.00 Calrad transformer. Can wait to swap out a Cinemag 2840! Although I am so happy with the sound I might just leave it alone!

Who knows? Guess I'll find out since I just bought one along with a U47 trafo for another mic based on an EF14.
 
Last edited:
EdgeGuy said:
I have most of my mics out on loan including my Earthworks.
All I had was an Oktava 319 , 012 and the Apex 460.
Recorded a Female vocalest who always sounded best on the 319.
O.K. I used the 460 (because I wanted to learn it) and found a setting somewhere between C & Omni.

The closer I switched toward Omni the brighter it got but not in a useful way.
I backed off and the mic got so smooth.
The mic was so smooth that I had to add the correct EQ to bring out some presence. The first time I ever EQed her.

This is in contrast to what others have said about this mic being overly bright in general. I wanted it more present.
I do have a new 460 with the "matching" shockmount in case they changed anything else.

Still later in the day I recorded sax and trumpet and got the best horn sound -for me- ever. I usually use the Earthworks for this with great results.
Not anymore.

The mic is not transparent. I want to make it so.
That is this mic's problem.
Question, does this mic use negitave feedback?
If so is there a way to decrease the amount?
Was that a stupid question?

Thanks.

P.S. Im getting another one because they are so damm fun ,cheap and sometimes wonderful sounding.
Click to expand...

My observation is that I never found the mic to be "bright" or "brittle" as some have described it. It sounded scooped with the original tube, but an NOS Tele 12AT7 made that better. The cap upgrades made it smoother. Removing the inner 2 layers of the grill made it more open.

The big problem with this mic is the capsule. It has a peak somewhere around the 2k region. That's one of the reasons it doesn't sound too transparent. Plus there are phase issues that may be related to the transformer. The biggest upgrade you could do to it would be to buy a Peluso capsule. That could run you a pretty penny. You could also replace the trafo with a Cinemag or Jensen.

The reason it sounds "brighter" toward omni is that an omni setup does not produce the proximity effect that a cardiod mic has. You'll notice that as you move toward figure 8, the proximity effect will increase.

Negative feedback to my understanding is used to get the signal as linear as possible, but I don't believe this circuit uses that. The CAD M37, M177, and M179 all use a negative feedback circuit.

And there's no such thing as a dumb question!
 
Last mod for me

PhilGood said:
My observation is that I never found the mic to be "bright" or "brittle" as some have described it. It sounded scooped with the original tube, but an NOS Tele 12AT7 made that better. The cap upgrades made it smoother. Removing the inner 2 layers of the grill made it more open.

The big problem with this mic is the capsule. It has a peak somewhere around the 2k region. That's one of the reasons it doesn't sound too transparent. Plus there are phase issues that may be related to the transformer. The biggest upgrade you could do to it would be to buy a Peluso capsule. That could run you a pretty penny. You could also replace the trafo with a Cinemag or Jensen.

The reason it sounds "brighter" toward omni is that an omni setup does not produce the proximity effect that a cardiod mic has. You'll notice that as you move toward figure 8, the proximity effect will increase.

Negative feedback to my understanding is used to get the signal as linear as possible, but I don't believe this circuit uses that. The CAD M37, M177, and M179 all use a negative feedback circuit.

And there's no such thing as a dumb question!
Click to expand...

I think when you get to this level of $cheapness$ the parts are going to change and inconsistancies creep in. When I first pluged in the mic I made a test recording which sounded bad. I swapped the tube for a Tele 12ax7 (after first trying a Tele 12at7 - RCA black metal 6072 - etc.) The sound became more alive and warm. I removed the inner 2 layers wire mesh. More open.

I have no 2k peak but rather it is too tame up there.
I had to boost around 2 - 3k on a female singer.
I want to swap out a cap or two next.

a) Which cap(s) effects the sound the most on this mic?

b) Do you know of a quality metal film cap that will fit in this mic?

c) Can I safely use lower value caps in there place? (they are smaller and cheaper)

Mylar caps aren't known for sounding very liner and a metal film cap might help even out the response (worth a shot if I can find one that will fit).
I know I will need at least two.

Im just going to do a cap swap to get rid of some haze and then put the mic in my mic closet as is.

Thanks

Bobby.
 
EdgeGuy said:
I think when you get to this level of $cheapness$ the parts are going to change and inconsistancies creep in. When I first pluged in the mic I made a test recording which sounded bad. I swapped the tube for a Tele 12ax7 (after first trying a Tele 12at7 - RCA black metal 6072 - etc.) The sound became more alive and warm. I removed the inner 2 layers wire mesh. More open.

I have no 2k peak but rather it is too tame up there.
I had to boost around 2 - 3k on a female singer.
I want to swap out a cap or two next.

a) Which cap(s) effects the sound the most on this mic?

b) Do you know of a quality metal film cap that will fit in this mic?

c) Can I safely use lower value caps in there place? (they are smaller and cheaper)

Mylar caps aren't known for sounding very liner and a metal film cap might help even out the response (worth a shot if I can find one that will fit).
I know I will need at least two.

Im just going to do a cap swap to get rid of some haze and then put the mic in my mic closet as is.

Thanks

Bobby.
Click to expand...

Mylar caps are pretty linear, especially compared to ceramic and electrolytic, which is what you're replacing with C8.

http://members.aol.com/sbench102/cap.html

The lower value you use, the less low end response you will have. Try to stay at 1uF for C8. You can probably find a metized polypropylene that will be the same size as mylar. If I remember right, mylars ARE metal film capacitors. They just use mylar as the dielectric rather than polyester.

http://www.americancapacitor.com/polyester.htm

Trust me, you can make it fit, just use a REALLY big hammer!
 
Sledge Hammer Time

PhilGood said:
Mylar caps are pretty linear, especially compared to ceramic and electrolytic, which is what you're replacing with C8.

http://members.aol.com/sbench102/cap.html

The lower value you use, the less low end response you will have. Try to stay at 1uF for C8. You can probably find a metized polypropylene that will be the same size as mylar. If I remember right, mylars ARE metal film capacitors. They just use mylar as the dielectric rather than polyester.

http://www.americancapacitor.com/polyester.htm

Trust me, you can make it fit, just use a REALLY big hammer!
Click to expand...

I'm getting close to hammer time.

Last question(s) before I order my caps.
I will stay with 1uf - but if I go higher will the bass also increase? - or is it already maxed out?
Also: I have been told that I can lower the VDC with no ill effect. The cap installed is 450v when there is only about half needed. Where Im going with this is getting the smallest size while improving the sound the most.
Sound being #1- I will hammer it in if I must.

Thank you
Bobby
 
PhilGood said:
Mark, if I were to rebuild as a C12, I would follow the ENTIRE schematic! Power supply included! The 460 would just end up just being a shell. The Elam 250 clones I built are working EXTREMELY well...
Click to expand...

No doubt the C12 is a good circuit.
I just pointed out that to turn the 460 into half of C24 type of the circuit would be quite an easy task, without getting into complications of complete rewiring of the PCB and PSU.
BTW, apart from some voltages and part values, aforementioned half of C24 and Ela M250 circuits look similar, so you could use existing 460 PCB for Ela M250 type of circuit, as well.
 
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