Apex 435 mods, anyone?

Hey Andybot,
thanks for the suggestions: I appreciate the help. I ended up going with Xicon 50V Polystyrene 5% for the 0.001uf and 1uf Kemet 100V Metallized Polyester %5 for the rest. Perhaps we can compare the mods when they're done. I just couldn't find the Panasonics or Nichion Caps in the right range from Mouser... If these don't work, I'll place a Digikey order next time.
 
apex 435 mods

Hi Earmark, is this the mods you were planning as posted by rmaier earlier in the thread?

Bottom line: replace C15,16,17 with polystyrenes; replace C3,4 with Black Gates; remove 1 layer of mesh (if you still feel like you need more air).

Id be interested in hearing how those turn out. I dont think i did anything on my 435 yet so i am going to record some test tracks. Its been a while since i used it.

A
 
That is indeed the mod I was planning: I have been using a pair of them in ORTF or XY90 for classical recording - I`m hoping this will give a bit more space, clarity, and a flatter response. They`ve been good workhorse mics for this king of recording thus far, but are about the be replaced by a pair of AT2035s. I`m hoping that the 435s will become a good secondary stereo pair for recording choirs with orchestra or as spot mics. For the test I may stick to acoustic guitar & vocals, though.

I will post samples as I get them. Should be a week or so for the goodie bag to arrive.

Earmark.
 
I did this mod today with 1000pf 630vdc polyester and 1uF 50vdc stack metal caps and it certianly improves the mic. The most noticable thing right away was how everything becomes more defined most obviously the low end.
A
 
You should also hear a difference in the shrillness of the high end. That really adds up with multiple tracks.
 
apex 435

Thats very tru PG, between this and the mackie pres their is some grossness happening
high up. Im glad i limit myself to 32 tracks of guitar and 14 of vocal.......on my folk stuff that is.
A
 
Side by side

View attachment Test 1 - 435 mod.mp3
View attachment Test 1 - 435 stock.mp3
View attachment Test 2 - AT2035.mp3
View attachment Test 2 - 435 mod.mp3

Hello Everyone,

I've included above a test of a stock Apex 435 vs. a modified one (C15, 16, 17: Xicon 50V Polystyrene 5% 0.001uf; C3, 4: 1uf Kemet 100V Metallized Polyester %5).

For the sake of interest, I've also run a second test with the same song on the modified Apex against an AT2035: a mic that costs a fair bit more. The high-pitch sound in the second tests is my fridge, unfortunately.

Thanks for the input on the mod, all: I am quite happy with the results. Perhaps I will post again if I remove a layer of mesh from the head basket... save that one for another day, I think.

The test: mono, diaphragms coincident, 18" from guitar/voice, diaphragms at center-line between instruments. The first verse of Jane, by BNL.
 
Last edited:
Im on dial up here so i cant download anything that big but it sounds like the results were to your liking.
Tell me if the mesh removal works out.
A
 
Hello everyone! This is my first post here, and I joined this forum specifically for this thread. I have had a 435 for several years now. It was actually my first ever mic when I started setting up my hobby recording set up. Anyway, I have been following this thread for some time now, and have just recently got into doing the acutal modding of my 435, which has been sitting in a drawer for a few years collecting dust due to it developing a strange low freq rumble, which I thought may have been a busted capsule or something.

I plan on doing most of the mods already described. Replacing C15, C16, C17 with polystyrene, C3, C4 with WIMA polypropylene(if it fits) or polyester film. Check FET bias and capsule voltage. I am also going to replace the lytics on the DC board just because mine seem to be bulging a bit. Quick question. In the last couple of posts, I saw that you guys are replacing C3 and C4 (0.22uF) with a 1uF. Just wondering why.

I have already done one mod to this mic, and that's replacing the capsule. The capsule I used is the RK 47 from microphone-parts.com. With the stock circuit, the capsule sounds so good. Smooth on the top, good presence, and nice bass response. The price is also very attractive. I have a spoken word and acoustic guitar recording that I could post a link to if you guys want to hear it in action. The included mount fits perfectly in the 435.

I have also bought some damping material from parts connexion to help kill body resonance. I'll do that once I get my mouser goodie bag.

Not sure if I will be removing any mesh layers. Someone on another forum made a good point about dirt and spit protection. Plus, with the K47 style capsule I am using, there may be little to no difference in the high freqs. May try it out.

Once I finish the cap mods and damping, I'll do some more test recordings and post them for anyone who wants to hear. I don't have a stock 435 to do direct comparisons, but hey, when it sounds good, it sounds good.

Well, that's it for me for the time being. I am looking forward to see how good I can make this mic sound, and I am glad to see that this thread is still alive and well! Thanks to everyone for their efforts on this so far. Makes things a lot easier!

Ryan
 
Hello Ryan,

the 0.22uf to 1uf cap change (to my understanding at least) is to tweak the high-pass filter component of the circuit. The higher the value of cap you get in the C3/C4 position the lower the hertz value that the mic will allow to pass through to your pre-amp/board/DAW. It is an attempt to extend and clarify the bass response of the mic. If you need more details, perhaps PG or Andybot can contribute...

Earmark
 
Hi earmark,

Thanks for the info! I just replaced C3/C4 with 0.22uF WIMA polyester film caps. I had ordered some polypropylene, but they are too wide unfortunately. I also replaced the ceramic on the back of the board (C17?) with a polystyrene. Then I did a test. These 3 caps alone did some magic. Cleaned up the mids and smoothed the highs. Mic sounds great! I am awaiting a 797 audio k67 capsule to put in this mic. Planning on using the RK 47 in a mic built from scratch. I do love a challenge!

Now down to replace those 2 caps and dampen the body.
 
Just wanted to post an update about the Apex 435 mod/roll off button.
I modded two mics to see if this was a fluke or something I can't account for.

After I changed the caps on the A435… C15, 16 and 17 with Xicon polystyrene .001uF 50V
C3 & C4 with Nichicon 1uf 50V and C1 & C2 with Nichicon .022uf 50V…


I noticed that the HP button no longer worked.
It has to be in the "roll off engaged" position for the capsule to get charged, if that makes sense.
There was a kind of background noise/hiss when the button is in the flat position.
I can see a minute amount of level trickling in but not enough to do anything.
It's like a self noise kind of thing.

I did mods to two different A 435s.
An older one with 4 wires connecting the two boards and a newer one with only 3 wires connecting the two boards.
I changed the capsule on the older one to a MP 47K and left the newer one with the stock capsule.
I did not make any changes to the capsule grill assembly.

Both mics sound and look (via recording waveforms) exactly the same.
And the both mics have the same button situation. It has to be pushed in for the mic to work.

And they are both noticeably shy in the low end. Even with increasing the values of the C3 & C4 caps.

And both have a pronounced midrange bump in the 2K>3K area.
The harsh brittle high end is gone and they are now very smooth sounding in the upper range.

Just thought you might like to know.
If anyone is still reading this thread, I'd like to know if you also encountered this problem with the HP button.

Thanks,
AQ.
 
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