Beginners Mic Mod

[Disease8]

I have been collecting parts for some mic mods for quite some times and nearly have all the parts for the;

Scott Dorsey:

http://www.pfarrell.com/music/shanghaimic.html,

the Royer Mod (not quite enough parts)

http://www.crodog.org/tubemic/tubemic.htm

and some of the Naiant Mic designs..

http://www.naiant.com/images/MSH_Kit_Mic.GIF

Naiant Phantom Powered tube mic:

http://www.naiant.com/images/MSH-4v2_Condenser_Mic.GIF

I have the tube for the  above MSH-4 and was planing on using a Behringer C-1 case and the diaphragm is back electret.

I have never done a proper mod before but really want to start as I have so many things I want to mod/build.

I have an old Apex 435 LDC which I would like to mod with something like the Scott Dorsey Mod but I neeed to find a more complete example..

I also have an Apex 180 is it? that can have the MXL 603 mods applied!

Any advice would be much appreciated, I know I should learn about electronics but I would rather do this making some small projects and modifications first as I have so many parts and mics ready to be worked on.

Thanks for your time!

D..

 

[tchgtr]

First...if you don't have a lot of solder technique, I would find some old junk circuit boards, and spend some time re-soldering and removing components, just to get proficient at it. It's quite easy to make matters worse by pulling up a trace on the PCB of a mic as you are modding it.

Second, start with the Dorsey circuit, as it is solid state and requires no dangerous tube voltages. Seems to me some of the Niant designs are non-tube also, so maybe start there.

I personally learned a lot from building the PSU for the Royer circuit, and it has been designed to be easy so that anyone can build it, and the tube voltages are only around 100V, so I would recommend this circuit next. It's very satisfying, and will teach you a lot about working with tubes.

Don't know anything about the other mics you named. On this forum, it's important to do your research, and somebody somewhere must have posted some info about these mics, or you should at least be able to find manufacturers specs on them.

Now for the obligatory questions that are often asked here of new mic modders (and for good reason).
Why do you want to mod them? Do they not sound good to you? My suggestion would be to find the schematics for them, and learn to read them if you don't already know how. That way, you can see if there are any electrolytic capacitors in the signal path that might be replaced with some metal film caps.
Mics (like FX pedals for guitar) are relatively simple circuits, and a good place to begin learning. I once found a nice video on YT of a guy going thru the Boss SD-1, explaining how he looks at schematics, and decides which parts to replace. I'll bet there are tons of vids on YT just like it.

I would first do the Dorsey and Royer circuits, which are good, elementary examples of basic tube and non-tube mics.They will teach you a lot.
Good luck!

 

[Gus]

In this thread it reads like the apex 435  is a china version of the Schoeps
http://www.groupdiy.com/index.php?topic=43933.0
IMO in that case the S.D. mod is a step backwards.

As tchgtr posted why do you want to change the microphone?
Also be carefull what you do
things to question
removing grill mesh layers
changing transistors and resistors

IIRC tchgtr built a circuit based on the Oktava 012 with a simple added part adjustment to the circuit I posted for the china 32mm capsules.  That might be a fun circuit to build.

 

[tchgtr]

Thanks Gus. I completely forgot how easy and how much fun that circuit was to build.
If the OP searches "P2P Oktava" it should be easy to find that thread.

 

[Disease8]

First...if you don't have a lot of solder technique, I would find some old junk circuit boards, and spend some time re-soldering and removing components, just to get proficient at it. It's quite easy to make matters worse by pulling up a trace on the PCB of a mic as you are modding it.

First what do you mean by pulling up a trace?

That is a lot of information thank you so much for the reply!

I have a portable studio and have been upgrading components over years to get the best possible sound so I can charge a professional fee and provide a professional product. Obviously the most important parts are the mic's and mic pre's (plus a/d and d/a conversion) .. I am aiming to get some really nice usable microphones out of this and also learn and experiment with electronics increasing my knowledge as a sound engineer and increasing my skill..

 

[Disease8]

In this thread it reads like the apex 435  is a china version of the Schoeps
http://www.groupdiy.com/index.php?topic=43933.0
IMO in that case the S.D. mod is a step backwards.

God damn it! I ripped out the innards of the Apex 435 already! Although I do think I kept the circuit I am not sure what condition it will be in now. So stupid! Well it kind of makes sense that not all mic's will benefit from changing the circuit if they have a cheap diaphragm! SIGNAL CHAIN! :-( 

Well I will look into the Octava one you mentioned I just don't want to have to keep buying parts when I am not making anything yet lol..

In the link you posted where the guy changes the diaphragm he mentions another circuit he is considering using instead of the stock one..

"There may be a step 3, which will be replacing the circuit with a km 84 or even an mk 319/219 style circuit, but I may leave that for a time."

 

[TheWoozle]

For easy mods, I would recommend the MCA SP-1, which retails for about 40$. There are lots of well documented mods you can do to this mic, which uses the Schoeps style circuit that's also in the MXL 903 I think, and others. Simply removing a mesh layer and replacing the capsule to fet cap makes these mics much better sounding. The innards are easy to get to, it's a simple design, and no lethal voltages. Plus the SP-1 is very cheap and sounds pretty good from the get go. The mods can really open one up.

I have an SP-1 in which I swapped the capsule cap and removed the inner basket lining--easy and informative. I'm going to replace the capsule itself next. It's a simple and rewarding project. 

 

[Davo]

Yup, working on a couple of these right now too.... just putting together my rig for biasing the fet.  Like Woozle said, good sounding Schoeps circuit... in the MXL 603, SP-1, v250 etc.
Do a search for Gus's mods on the 603

Another great resource is the micbuilders forum on yahoo... look for the genchinamod.pdf for a bit of a different take on these mods

cheers

 

[Blue Jinn]

The schematic for the SP-1 can be found here: http://www.nvrecording.nl/nhc/AudioTechniek/mxl990_sp1mods/mods_en.htm The same circuit is in a *lot* of mics.

There is also the zapnspark* mod. I have the files on another computer. He also replaces the transistors, ( you have to re-bias the FET if you replace it,) and  he also directly couples the capsule to the FET.  I will try and post that.


*GenChinaMod

 

[telefunk]

My opinion is that if the capsules are not changed, these mods are not worth it. K67-type capsules without some type of HF limiting circuit are hopeless IMHO.

Change the capsule to some more flat response types and these mods are beginning to really make sense.

 

[tchgtr]

  Agreed, to a certain extent. Many of these capsules will defy any attempt to make them sound better, which is why well-built capsules cost so much.
  However, Gus came up with a LPF for the Oktava MK-012 circuit which works great, making it adjustable for LDC mics, since the circuit is designed for SDC diaphragms.
  There are other circuits on this forum that also try to account for the K67 capsule response, but in general, I agree with you that the quality of these capsules is a major hurdle to making these mics sound better. However, every so often you find one that isn't too bad, and can be EQ'd.
  The circuit found in the MXL 9000, also has a LPF cap, which can be adjusted to make the mic even darker, but it's not my favorite tube circuit, tho not bad with some tweaks.

 

[Gus]

The 603 is not a MOD it is more of a change of caps to ones that FIT and sound OK.  A mod would be a rework of the circuit and/or capsule.  Changing caps is not a mod IMO.

The 012 circuit change is a SIMPLE addition of one cap to the stock circuit.

IMO the increasing of the coupling cap values can be a bad thing in the transformer-less China type circuit posted about in this thread.  Try matched .022ufs for a close worked vocal microphone, adding more lows can be a bad thing in the mix.

I have built a microphone with a 797 k67 like capsule and it sounds very good.  It all about understanding what does what in a condenser microphone.  My adjusted older SP C1 and MXL 2003(not a) sound OK as well with the stock capsule.

 

[tchgtr]

I have one of the older 2003s also, and have changed some caps and really like it.
By SP, do you mean Studio Projects? I've got a B1, and have kept it stock for when I want that scooped mids sound. Nice on toms, or as room mic. Those 797 capsules are OK.

 

[Blue Jinn]

I couldn't find the Oktava 012 mod referenced above, unless this is the thread:

http://www.groupdiy.com/index.php?topic=23961

Also, I've attached the SP-1 mod. Note that the part numbers are different then the actual PCB. The part numbers at the link I posted above match.

 

[tchgtr]

  Here is that thread, which I just found by searching the exact phrase I quoted above.
http://www.groupdiy.com/index.php?topic=41986.msg522622#msg522622
  It's not a mod, just a very detailed discussion of the circuit with an excellent explanation by PRR and other local gurus, plus Gus's suggestion of a way to tame the highs in the circuit so it can be used with LDCs, as the circuit is originally designed for SDCs. It's worth taking the time to read.
  We are not modding the circuit, just building our own from scratch to put in LDC mics. It's a very easy circuit to build, and sounds good. Not hyped or "in your face", but flat and honest. You can adjust the LPF for your capsule, as is explained in the thread.
  I used the parts and circuit board from my MXL 2001 to do it, so I didn't even have to buy any 1G ohm resistors.

 

[JimiDeez]

:-[HELP HELP HELP!
Just replaced the input cap and 2 resistors in a Oktava MK319 and now have NO SOUND!
Retraced my steps, tested the resistors & replaced the cap with another. Still nothing.
Any thoughts? Thanx a Bunch Gang in advance for helping the NOOBIE, Jimi.

 

[Winetree]

My opinion is that if the capsules are not changed, these mods are not worth it.

I had Jim Williams mod two SP-1s.
He replaced almost all of the stock PSB componets and left in the stock capsules.
They sound amazing.

 

[sr1200]

Jimi, you need to start tracing out your circuit.  Make sure phantom is getting in and hitting what it needs to hit.  then double jeck your solder joints and make sure there are no cold solders.  Hopefully you didn't cook anything.

 

[tchgtr]

My opinion is that if the capsules are not changed, these mods are not worth it.

I had Jim Williams mod two SP-1s.
He replaced almost all of the stock PSB componets and left in the stock capsules.
They sound amazing.

I don't doubt that, but here's a GS quote from Jim in 2011:

"Capsule replacement is easy, just 2 wires to solder and 2 screws to mount it.
I have replaced several capsules in my MCA SP-1 mics with great results.
I bought some cheapo Chi-comm K47 and C12 capsules from these guys and they sound wonderful.

K47 and CK12 Microphone Capsules | Microphone Parts

The K47 is mid heavy and costs $99, the C12 capsule is $89.

Search other threads on changing the capacitors in these.

I put them into my $49 MCA SP-1's I got from:

www.pssl.com

They also easily refit the cheapo MXL 990."

 

[sr1200]

Arent there different voltages needed for backplates for different capsules though?  I was under the impression that you can't just arbitrarily swap out capsules.  Maybe thats just on tube mics?  So confused now!