Chinese LDC Cap Replacement Questions (noob)

[ghetto3jon]

i've been reading on HR, GS, and PP about cap replacement on chinese microphones, and i'd like to give it a go. i have a transformerless PPA LD-None.

one of the most popular suggestions is to change the capsule/gate capacitor (the one on the back of the singer-side board) to a 1000pf polystyrene cap. does this apply to the LD-None? is this the correct replacement?:

http://www.mouser.com/Search/Product...RYYGpufA%3d%3d

and without a schematic, how can i determine what other caps to replace?

here are some pics:

http://www.thebrotherkite.com/stuff/ppa01.jpg
http://www.thebrotherkite.com/stuff/ppa02.jpg

[rmaier]

Hmmm. Sure looks alot like an Apex 435. Check out this thread (or search Apex 435):

http://www.homerecording.com/bbs/sho...light=Apex+435

[ghetto3jon]

very interesting...it does look very similar. assuming they are the same, i should replace:

C3, C4, C15, C16, and C17. is C15 the "gate" cap on the back of the PCB? i haven't taken it apart yet.

applying some advice from Gus's 603 mod (http://www.prodigy-pro.com/forum/vie...ght=%2A603+mod)

i should replace C15, C16, and C17 with these:
http://www.mouser.com/Search/Product...RYYGpufA%3d%3d

and C3 and C4 with these:
http://search.digikey.com/scripts/Dk...?name=P4667-ND

is that correct?

(thanks for your input, rmaier. do you have a 435 schematic? i can't find one for the LD-None)

[rmaier]

Sorry, no schematic....

Replace C15,16,17 with the Mouser part you have listed.

I replaced C3 and C4 with Black Gates, so I can't say how your metal film caps will sound. Guess I'll have to pick up a pair of 603s and see.... My wife's gonna freak.

[PhilGood]

When you get to a point where the mic seems ok after capacitor replacement, make sure to upgrade the capsule. I just put a K47 style capsule from Soundelux (David Bock) in a Royer tube circuited V67G with Cinemag transformer and tracked a vocal with it.

Oh...my...God!!!!!!

I will never track vocals with a chinese mic EVER again!!!!!

Consider a Peluso PK47! Trust me!

[ghetto3jon]

but those metal film caps will work, correct? (as far as value and size and stuff, i don't know too much about this!)

(thanks so much for your help)

[ghetto3jon]

oh, and can anyone else confirm that the LD-None is indeed the same thing as the 435? i'm going to move forward on this mod, but i'm forgetting that all of this is based on the 435 circuit, which could be difference...

is there anyway to confirm that those are the caps in the audio path on the LD-None as well?

(if i go through with this, i promise pics and before and after sound clips to hopefully help someone who may be interested in the same type of mod in the future)

[P. Glaser]

Looking forward to that.

[rmaier]

Originally Posted by ghetto3jon

is there anyway to confirm that those are the caps in the audio path on the LD-None as well?

I wish I could give you a better answer other than the observation that layout of the circuit boards appears to be identical to the one I posted on an earlier thread. Philgood's advice really helped me do the mod. Maybe he would be willing to comment...

When I originally did the mod I got in touch with Apex to try to get a schematic. They referred me to their website, where none were to be found. Bummer.

Good luck with the mod. I'd also like to know how metal film would compare to Black Gates in C3 and C4. Anyone care to chime in?

[ghetto3jon]

no sweat, rmaier...you've been so much help already.

if someone (Philgood? anyone else?) can confidently identify those caps as the ones to change, i'll jump in and post my results.

[PhilGood]

Sorry, I had to look through everything again because I haven't been following too much (I'm a little distracted). The first polystyrene you have listed for C15 is correct and will make the biggest difference. C3 and C4 look good with the .22uF film caps as well. Black Gates are a formula to make Electros as linear as film, so I would go with film caps by default.

Not sure how much of a difference C16 and C17 would make, but you could try and see. Replace C15, C3 and C4 first, then make a before and after with C16 and C17 and see if you like it.

[ghetto3jon]

thanks so much, PhilGood. i appreciate you sharing your knowledge.

this post might go dead for a bit, i have to place the order and perform the mod...but i'll post before-and-after files when it's all done.

[PhilGood]

You could change the .22uF to .33uF or .47uF if you can find ones that will fit. Might open up the lows a bit.

[rmaier]

Is David Bock selling capsules?

[PhilGood]

Originally Posted by rmaier

Is David Bock selling capsules?

No, I managed to acquire a couple from someone who had a few to sell.

They're very similar to the Peluso PK47, which you can get from John.

[ghetto3jon]

the parts have been ordered...once they arrive i'll post the results (assuming i don't screw it up). thanks again for all the help.

[ghetto3jon]

i performed the mod tonight. here are some pics:

http://www.thebrotherkite.com/stuff/ppamod01.jpg
http://www.thebrotherkite.com/stuff/ppamod02.jpg
http://www.thebrotherkite.com/stuff/ppamod03.jpg
http://www.thebrotherkite.com/stuff/ppamod04.jpg
http://www.thebrotherkite.com/stuff/ppamod05.jpg

i won't be able to post the before-and-after samples until next sunday when i get back to the studio, but i can tell you that the mic works and sounds great.

hey those in the know (PhilGood, rmaier), should i be concerned with my different lead lengths on C15 for any reason? i have a few more caps, so i could try to make it look prettier...but it does work...so if it ain't broke, i suppose.

[rmaier]

Nice job ghetto3jon. I'm no expert, but I doubt the lead length is really much of an issue. In fact, it looks better than some of the work I've seen coming out of the factory. If it were my mic, I'd leave it alone. Love to hear some clips.

All this talk made me run out and pick up a pair of Apex 185s (read MXL 603s). I have a few 1000pf polystyrenes kicking around which I'll pop in as soon as I have a bit of time. I'd like to try replacing the .22s with Panasonics as well and maybe mess around with a few of the larger values that Philgood and others have mentioned, but ordering the stuff from US suppliers is a bit of a pain for those of us living in the great white north. Anyone know of a good Canadian supplier?

[ghetto3jon]

here are the results (Mic -> SCA A12 -> MOTU 828mkII):

Pre-Mod
http://www.thebrotherkite.com/stuff/ppa_guitar.aif
http://www.thebrotherkite.com/stuff/ppa_vox.aif

Post-Mod
http://www.thebrotherkite.com/stuff/ppa_guitar_mod.aif
http://www.thebrotherkite.com/stuff/ppa_vox_mod.aif

[dgatwood]

Originally Posted by rmaier

Nice job ghetto3jon. I'm no expert, but I doubt the lead length is really much of an issue.

For high frequency electronics, you really need to keep the leads short. For audio frequency stuff... eh. You probably get more impact on the sound from the phases of the moon.

I would note that longer leads are at greater risk of bumping something when you take the thing apart, so you don't want them to be ridiculously long. That said, what I'm seeing there looks fine to me.

[PhilGood]

Originally Posted by ghetto3jon

here are the results (Mic -> SCA A12 -> MOTU 828mkII):

Pre-Mod
http://www.thebrotherkite.com/stuff/ppa_guitar.aif
http://www.thebrotherkite.com/stuff/ppa_vox.aif

Post-Mod
http://www.thebrotherkite.com/stuff/ppa_guitar_mod.aif
http://www.thebrotherkite.com/stuff/ppa_vox_mod.aif

This has been my experience as well. The midrange gets better, the sound has more presence, and the top end is less fuzzy. It doesn't sound so far away and sizzly.

[ghetto3jon]

thanks for all your help, guys.

should i give C16 and C17 go? i have the parts...

[craigmorris74]

Good job ghetto3jon. That mic has definitely become usable. It's still bright, but in a much nicer way. It was sizzling before.

[PhilGood]

Originally Posted by ghetto3jon

thanks for all your help, guys.

should i give C16 and C17 go? i have the parts...

Well, since you have the parts, and probably the time, I say go for it.

Certainly couldn't make things worse.

[dgatwood]

Next thing to do is probably to replace all those ??tantalum?? parts.