Internal mic vs external mic

[Schertler]

This is the link to the theme of my micup (mic pickup) Mr. Acoustic system of miniature condenser and dynamic capsules, it tells and shows everything. I was quite angry of any type pickups and decided forgetting about them totally...... experimenting with dynamic capsule took some time but the result was over of any expectations...... I am lazy for making some demo-recordings, but I will put them if I take one.

https://www.acousticguitarforum.com/...d.php?t=530232

Oktava MKE-3 mics are still widely manufactured and available in Russia, the best would be searching Russian online stores.......
Made in 1990s, Oktava MKE-5B is the same MKE-3 capsule built into superb metallic housing and attached to the miniature DI box (miniature audio transformer) with XLR out, it was a professional TV mic and never available for sale ...... if you are lucky, you may find some.....
This 10mm capsule PRIMO mic is similar to MKE-5, I would love to hear of any experience of using PRIMO mics in the internal micup systems.......

[lkingston]

An internal mic cans sound wonderful blended in with a pickup. I even record that way sometimes.

[guitarman68]

Sometimes I use an external mic on a boom stand, most of the times I use an internal mic. Thirty years experience with dual source systems using Highlander IP-2, D-TAR, Sunrise/AKG, Baggs, Fishman Rare Earth Blend (I loved it and used it for more than ten years). Always trying to dial in as much mic as possible (up to 50/50). The first internal mic I really liked was the K&K Trinity, which to my ears sounded more realistic compared to the above mentioned while being more feedback resistant. These days I mostly use DPA 4061 - pretty expensive but you can find them used and reasonable prices. A tad more detailed compared to the K&K, which IMO still is an incredible fine sounding mic for the money.
High Pass Filter (HPF) is king when using internal mics.
I like the sound of the internal mic and even used it sometimes when recording.
I also own a ToneDexter (great piece of gear) but still prefer a real mic.

Just a note:
I have a Mimesis Kudos on order. This humbucker/mic combo pickup is designed by Mike Vanden, who designed the Fishman Rare Earth and sold it to Fishman.
I'll report back.

[Schertler]

Lot of 38 MKE-3 capsules on REVERB!

[6L6]

I'm definitely NOT a fan of internal microphones.

[rb1591]

As someone who enjoys experimenting with pickups, mics, etc., let me say that this is one of the most interesting threads I've read.

Shertler, thanks for documenting your experiments with dynamic capsules and ECMs. I read all your posts in this thread and as well as in the linked one. Please allow me to ask a couple of questions, particularly about using the Oktava MKE-3 capsule.

Building a pre-amp is a bit too complicated for me, so step one in my experimenting is simply to add an Oktava MKE-3 to my existing pickup (Barbera Soloist).

I’ve attached links to two documents about 1)LR Baggs MixPro preamp and 2)LR Baggs Buffer Jack. The Buffer Jack is a product that was discontinued years ago, but I hope to find one as it seems to have good use in this context.

When used with the Baggs MixPro preamp, the jack enables a piezo pickup to be combined with a mini-mic without any crosstalk. The MixPro also includes a low-cut filter on the mic channel and powers the mic externally – no batteries in the guitar.

MixPro

Buffer Jack

Any thoughts on this approach from any of you forum folks would be appreciated.

One more question: Is it necessary to “build from zero” a housing or special mounting mechanism for the MKE-3 capsule. In my experiments, I have often crafted a mic holder from a piece of stiff but flexible wire and heat shrink tubing then found a simple way to mount the whole thing on the guitar back or side. My goal has always been to keep it very simple in an attempt to isolate the mic from mechanical vibrations that might produce rumble.

[Doug Young]

Originally Posted by rb1591

Any thoughts on this approach from any of you forum folks would be appreciated.

One more question: Is it necessary to “build from zero” a housing or special mounting mechanism for the MKE-3 capsule.

I've not seen the buffer jack, and am not sure what it really does or why it would be needed. I've never experienced "cross talk" between the mic and pickup in my setups. Since I'm blending them anyway, I'm not sure why it would matter if it did occur. Clearly Baggs thinks it's an issue to have created this. I do have a MixPro, and that works nicely. Handy little preamp.

As far as the mic mount, I've not used the MKE-3, but I just use a simple wire/cable clip and a bit of foam to attach and shock mount the mic, simple and cheap. Someone else suggested just 2 pieces of velcro, which would think would work. I just posted photos of my mount in another thread, seems like we have parallel discussions of internal mics going on right now.

[rb1591]

Thanks, Doug. The reason I thought about the buffer jack is because it handles 3-wire mini mics like the Oktava and I don’t know how to wire that to a TRS endpin. I’ve only experimented with 2-wire ECMs. And yes, IMO the Mixpro is a sleeper. I picked up a used one at a great price and it sounds very good. EQ is limited but if needed I can get that somewhere else in the chain.

Always appreciate your thoughtful responses.

[Doug Young]

Originally Posted by rb1591

Thanks, Doug. The reason I thought about the buffer jack is because it handles 3-wire mini mics like the Oktava and I don’t know how to wire that to a TRS endpin. I’ve only experimented with 2-wire ECMs. And yes, IMO the Mixpro is a sleeper. I picked up a used one at a great price and it sounds very good. EQ is limited but if needed I can get that somewhere else in the chain.

Always appreciate your thoughtful responses.

I'm not sure what the buffer jack does in that respect, but every 3-wire mic I've used (like the Audix L5O I mostly use), you just wire one of the wires to ground. I always forget which wire is which :-), but it's easy to try and figure out. But the buffer jack may do something useful as long as you have it!

The mixpro's great for low-overhead situations, like showing up at an open mic where you don't want to be plugging into some random board, but also don't want to be setting up a floor preamp and so on. Walk up, plug in, and no one even knows you're using a preamp.

[Schertler]

Originally Posted by rb1591

As someone who enjoys experimenting with pickups, mics, etc., let me say that this is one of the most interesting threads I've read.

Shertler, thanks for documenting your experiments with dynamic capsules and ECMs. I read all your posts in this thread and as well as in the linked one. Please allow me to ask a couple of questions, particularly about using the Oktava MKE-3 capsule.

Building a pre-amp is a bit too complicated for me, so step one in my experimenting is simply to add an Oktava MKE-3 to my existing pickup (Barbera Soloist).

I’ve attached links to two documents about 1)LR Baggs MixPro preamp and 2)LR Baggs Buffer Jack. The Buffer Jack is a product that was discontinued years ago, but I hope to find one as it seems to have good use in this context.

When used with the Baggs MixPro preamp, the jack enables a piezo pickup to be combined with a mini-mic without any crosstalk. The MixPro also includes a low-cut filter on the mic channel and powers the mic externally – no batteries in the guitar.

MixPro

Buffer Jack

Any thoughts on this approach from any of you forum folks would be appreciated.

One more question: Is it necessary to “build from zero” a housing or special mounting mechanism for the MKE-3 capsule. In my experiments, I have often crafted a mic holder from a piece of stiff but flexible wire and heat shrink tubing then found a simple way to mount the whole thing on the guitar back or side. My goal has always been to keep it very simple in an attempt to isolate the mic from mechanical vibrations that might produce rumble.

Hello rb1591,

Thank you for your interest! First of all, I have to note that my thoughts and/or recommendations are all based on these two options - quality and economy. It is not a hard task to realize a total budget needed for a very basic and quality gear for achieving good results with your instrument and its true amplification...... Yes, DPA mics are known for their sonic characteristics and they are probably the most expensive etc...., so I would never get my acoustics amplified without finding these alternatives!

Commenting on your questions......

1. Oktava MKE-3 in its factory setup is grounded Positively and you will have to use internal 3-4.5V battery for its powering.

2. I do re-wire my MKE-3 mics as shown on the image, you will have to disassemble the housing and change pin of the FET-transistor to get a 2-wire MKE-3 this way powering through the cable from your preamp:



3. MKE-3 should work fine with any external preamp, but you have to check the balance between the outputs of the two sources - pickup and MKE-3 - in the preamp for symmetrically dialing volume controls of the two.

MKE-3 does require some modification for making it 2-wire ECM and working from a standard Negative-grounded powering source, but you can also use it with internal 3V battery...... and buy something more important by those few hundred dollars saved on a little condenser mic !

[euraquilo]

Originally Posted by Doug Young

I'm not sure what the buffer jack does in that respect, but every 3-wire mic I've used (like the Audix L5O I mostly use), you just wire one of the wires to ground. I always forget which wire is which :-), but it's easy to try and figure out. But the buffer jack may do something useful as long as you have it!

Yeah, I started that other thread ("internal microphone experimentation") but this one is picking up some good info so I'll carry on over here.

Anyway, I have been planning (once my order for jacks arrives) to turn the AT831a's balanced signal to unbalanced by wiring the neg (or "cold") lead to ground. Phantom power, however, may complicate this. I found an interesting discussion on another forum site:

https://www.gearslutz.com/board/show...69&postcount=3

BTW, applying phantom power across an unbalanced mic is more likely to cause damage to it than the mic pre. Once again, if the mic pre uses a transformer, you run the risk of magnetizing it, which will increase distortion, but that is fortunately only a temporary effect. OTOH, if the mic diaphragm is connected directly to the output (no transformer in the mic), you might destroy the very tiny wires in the voice coil. It would also certainly cause distortion.

You might get away with connecting the mic between pins 2 (hot) and 3 (shield). That leaves the mic without a ground reference which might be noisy, so I would connect pin 3 to 1 with a capacitor. Probably 10 uF @ 63V would be sufficient, with the positive end to pin 3.

That's all a bit beyond my knowledge of electronics, but I've seen in Fishman literature the need to add a cap between pin 3 and ground, too.

But Doug - did you add any kind of capacitor in your installations?

[Doug Young]

Originally Posted by euraquilo

[INDENT][I]BTW, applying phantom power across an unbalanced mic is more likely to cause damage to it than the mic pre. Once again, if the mic pre uses a transformer, you run the risk of magnetizing it, which will increase distortion, but that is fortunately only a temporary effect.

....

But Doug - did you add any kind of capacitor in your installations?

No, I don't. Notice that this discussion is talking about phantom power, and causing issues with a mic pre that provides phantom power. You won't be using phantom power, you're using a "bias voltage" powering scheme, quite different. This always gets confusing, because most of the non-guitarist world hasn't encountered this approach (it is also used by some wireless packs and a few other places). Everyone thinks as soon as you mention a condenser mic that you're using 48 volt balanced phantom power, but we're not.

Here's a few links to the difference:

https://www.shure.com/en-US/performa...s-bias-voltage

This is a good one, with lots of circuit diagrams. Note that for our use, all of the 3-wire versions won't work. The one we use for internal guitar mics and with preamps like the MixPro is the one labeled "Super-simple powering circuit". Note that even in this article, they seem to constantly assume you are plugging into a 48-volt phantom power source, which is not the case for internal guitar mics into a suitable preamp.

https://www.epanorama.net/circuits/m..._powering.html

[euraquilo]

Hm.

This makes me think my idea of using my AT831a mic might not work. The 831a is permanently wired to a battery capsule/belt clip that holds a 1.5 battery and outs to a balanced XLR cable. The belt clip can pass phantom power (and the battery doesn't even need to be present for the mic to operate on phantom power). I had hoped to simply sever the cable to the battery capsule and send an unbalanced lead (by shorting the neg to ground) and soldering to the ring/sleeve of strap-button jack (the tip/sleeve going to a mag pickup). Then on the outside of the guitar I could either re-insert the battery capsule or just rely on phantom power from a preamp or mixer alone.

It seems in the very least I'll need to have the battery capsule inline because it looks like it has circuitry to modify 48v phantom power to be acceptable to the 831a. Or perhaps I just need to use another lavalier mic.

Such good info here!

[Doug Young]

Originally Posted by euraquilo

Hm.

This makes me think my idea of using my AT831a mic might not work. The 831a is permanently wired to a battery capsule/belt clip that holds a 1.5 battery and outs to a balanced XLR cable.

If it can be powered by a battery, I expect it can be powered by your MixPro. The belt clip is probably converting the 48 volt phantom power to 9 (or 1.5) volt bias power. It's easy enough to do, just a voltage divider, and tapping off one side of the phantom. It sounds like the belt pack is just an adaptor that is trying to allow you to connect with what nearly everyone except guitar preamps use.

[euraquilo]

Originally Posted by Doug Young

If it can be powered by a battery, I expect it can be powered by your MixPro. The belt clip is probably converting the 48 volt phantom power to 9 (or 1.5) volt bias power. It's easy enough to do, just a voltage divider, and tapping off one side of the phantom. It sounds like the belt pack is just an adaptor that is trying to allow you to connect with what nearly everyone except guitar preamps use.

My situation is a little different. I don't have a MixPro, but I do have a Fishman Acoustic Blender (as well as normal sources for phantom power). And the part of the Blender manual that describes using a Shure GLM200 mic has led me to believe I could use the 831s. I've been comparing the Blender's manual with the GLM200 spec sheet.

1) Even though the GLM200 specs says it needs 12-48v of phantom power, the Blender actually only supplies 4.5v. Fishman may have made come kind of customization, though.

2) The GLM200 spec sheet seems to be clear that both audio (hot and cold) leads are needed to supply the phantom power ("Phantom power, 12 to 48 volts DC, positive voltage on pins 2 and 3 with respect to pin 1 of output connector.") but the Blender manual demonstrated there need only be the hot lead. I suspect I just don't understand the language surrounding phantom power because I've obviously seen that it can be sent on an unbalanced cable.

3) The zener diode shown in the illustration and in the text seem to be pretty important ("NOTE: The zener diode MUST be wired to the output of the GLM-200. (Microphones installed without the zener diode are not covered under warranty.)". That's why I latched onto the similar language in that Geerslutz discussion.

It looks to me like I could plug the 831 into the Blender, but if I were to plug it into something supplying a full 48v I will need to have the battery component (with any of its specialized circuitry) between the mic and the 48V to protect the mic.