Miniature dynamic mic pickups out of 140-160 Ohm earplug capsules

[Mikheil]

Those are earphone capsules, not real microphones.

You have what you have and be grateful for that, you can´t boost highs which were never there to begin with.

I guess your guitar also use Piezos under the bridge, which tend to have way too much Highs, a judicious mix of both pickup outputs will give you a very balanced end result.

Piezo: I have tested and then removed all type of piezo elements few years back, I do not use piezos anymore, they ruin the guitar's overall sound .......... however, piezo does not really sound bad in my ukulele, they sound OK with nylon strings, double-basses etc.....

Well, I am sure after cutting LF withing this circuit, then it should be possible to add more highs with external EQ, isn't it ?

Any more ideas on how to add more Highs in this circuit ?

[rjb]

<buzzkill>

Thank you for your feedback!

SCREEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEECH, har, har. Ahem. Excuse me.

I fear that if used for live amplification, your setup may be prone to acoustic feedback.
Because:

...these dynamic capsules might function not only as mics capturing sound waves but also capturing vibration by their metallic housing,

</buzzkill>

Limiting the bass frequencies with smaller coupling caps (as you noted) should help (I think).
And if Fahey sez its OK, its probably OK.

- rb

[bbsailor]

Piezo: I have tested and then removed all type of piezo elements few years back, I do not use piezos anymore, they ruin the guitar's overall sound .......... however, piezo does not really sound bad in my ukulele, they sound OK with nylon strings, double-basses etc.....

Well, I am sure after cutting LF withing this circuit, then it should be possible to add more highs with external EQ, isn't it ?

Any more ideas on how to add more Highs in this circuit ?

To get the best response from piezo elements you need to use a high impedance (3M ohm to 5M ohm) active buffer close to the piezo element to eliminate cable capacitance and other external loading.

Joseph J. Rogowski

[Mikheil]

To get the best response from piezo elements you need to use a high impedance (3M ohm to 5M ohm) active buffer close to the piezo element to eliminate cable capacitance and other external loading.

Joseph J. Rogowski

Yes, I used all those piezo-elements with B-Band on-board preamp/EQ (10 mOhm input impedance)......
I find the piezo pickup to be just the compromise for steel-string acoustics, personally I would go for the worst mic-preamp rather than the best piezo......

[Mikheil]

I fear that if used for live amplification, your setup may be prone to acoustic feedback.

Yes, attaching to the sound-board makes the capsules more prone to feedback, this technique requires a very special type of surface mounting ...... as an alternative, placing some thin buffer-material in-between the capsule and guitar's sound-board might help someway, OR, housing the capsule into such buffer-material cylinder and then attaching this cylinder to the guitar's top ........

If am able to find the best way of how to attach the capsule to guitar's top, I will get the most advanced acoustic guitar pickup ever ...... and, even better if getting higher-impedance capsules of 200-300 Ohm .......

Thank you for sharing your experience and thoughts!

[rjb]

If am able to find the best way of how to attach the capsule to guitar's top, I will get the most advanced acoustic guitar pickup ever ......

Perhaps, but... surface-mounted microphones have been around for a long time....

Have you heard of MEMS (Micro-Electrical-Mechanical Systems) microphones?
Here's a manufacturer's tutorial: http://www.st.com/content/ccc/resour...DM00103199.pdf

Here's a commercial product: http://www.ikmultimedia.com/products/irigacousticstage/
I've got one of these guys. I don't play out much, but have used it three times so far, in noisy dance environments. So far, so good.

-rb

[Mikheil]

Perhaps, but... surface-mounted microphones have been around for a long time....

Have you heard of MEMS (Micro-Electrical-Mechanical Systems) microphones?
Here's a manufacturer's tutorial: http://www.st.com/content/ccc/resour...DM00103199.pdf

Here's a commercial product: http://www.ikmultimedia.com/products/irigacousticstage/
I've got one of these guys. I don't play out much, but have used it three times so far, in noisy dance environments. So far, so good.

-rb

Thanks! Yes I am aware of MEMS, moreover, regularly checking their news every year since 2012; however, MENS considered a new type of mics and expected to totally replace ECM on the market do not or very rarely give Frequency Response specs on their mics which are somewhere 100-10000 Hz, SNR is over 60 dB etc...... Knowles, the manufacturer has BOOM Series mics with better characteristics and sold for over $50 ......
The new IKmultimedia product is the first guitar system built on MEMS technology but I do not know which real guitar performer uses them .....
I do not think that MEMS compete where the true audio specs are required ...........

Dozens of pickup systems are on the market today but the most even very expensive unit might be disappointing, only personal experience makes you think right and able to build something for $10 that would win over some $200 worth manufactured gear....... but, having one quality little mic is a must because the sound begins with mics only.....

[rjb]

I myself need to catch up on learning about MEMS mics & pickups. For others who are also behind the times, here's an article from way back in 2009: http://www.analog.com/en/analog-dial...c-pickups.html

Yes, this is still a developing technology with little track record. As with any new toy, I expect that performance will improve, while prices will decline. Currently, the iRig unit's MSRP is $100, but you can find them for $70.

I do not want to discourage your experiments using earbuds as mics. I do question whether they will be "the most advanced acoustic guitar pickup ever." Which, I'm guessing, was a tongue-in-cheek assertion anyways....

Have fun,
-rb

Notes:
- You probably wouldn't want the frequency response of a guitar mic to go below 100 Hz; you'd just have to add a rumble filter.
- I knew Rick Turner had mentioned accelerometers somewhere here awhile ago. Found a post- he sez the issue with soundboard transducers in general is "location, location, location." http://music-electronics-forum.com/s...l=1#post191356

[Mikheil]

Yes, this is still a developing technology with little track record. As with any new toy, I expect that performance will improve, while prices will decline. Currently, the iRig unit's MSRP is $100, but you can find them for $70.

I do not want to discourage your experiments using earbuds as mics. I do question whether they will be "[COLOR=#3E3E3E]the most advanced acoustic guitar pickup ever." Which, I'm guessing, was a tongue-in-cheek assertion anyways....

Thanks!, Most of the piezo-elements cost around few cents, however some manufactured piezo-pickups are sold for over 100 ......
'The most advanced pickups' and all other notes should be considered from the local point view only due to a simple lack of almost everything related to steel-string acoustics and its gear, locally you will not find neither a worth instrument nor electronics to purchase, so I consider all these very basic wins as most-advanced ..... :-) otherwise such devices purchased overseas would cost far over ...... I have purchased new acoustics online which is a budget-category instrument but locally it definitely might be considered as high-budget guitar ...... moreover, I am expecting the guitar to arrive CITES permit to be issued which is a mandatory to legally transport the instrument out of EU ...... our planet is called Earth but, depending on geography, living is very different everywhere and quite often it hardly can be called as living on the same planet....... :-)

[Mikheil]

It should certainly be interesting to hear that these dynamic capsules can be easily wired in-series as piezo-discs are wired in-parallel ...... This way you get higher impedance thus getting higher output as well as several mic-pickups installed at different spots of the instrument's top !

I had never experimented on that thinking of its anti-scientific nature, never heard of wiring dynamic microphones in-series, however, these earplug dynamic capsules work just great wired in-series.

Another interesting fact is that there might be NO need to install any pre-preamp electronics in to the guitar's body, the low-impedance <1 mV signal from the dynamic capsules easily travels through unbalanced guitar cables - 4M guitar-preamp and 4M preamp-amp - over 8 M in total.

However, good shielding and proper grounding must be controlled at every step of assembling and installation.

[Mikheil]

Hi All,

Just wanted to share my project with those who never been happy with the most of acoustic pickup systems, or wished to find alternatives to expensive internal condenser microphones.

This thread is about the pickup-element built out of little dynamic capsules taken from some high-quality earphones/earplugs/earbuds .... As you may expect, higher coil resistance capsules do perform the best, the higher coil resistance is, the better. There are some earphone capsules with over 600 Ohm coils on the market, but I do use the ones with 140-160 Ohm coil resistance and they do the tasks just phenomenally.

With some dedication and accuracy you are on the right way to equip your acoustics with the unique pickup-element capturing both the sound waves as well as sound-board vibrations.

Very briefly, in the form of a listing, on how it is made and what are the basic rules and steps to follow and get the one built successfully:

1. Higher coil resistance capsules are the must;
2. Metal-housing capsules are the must;
3. There should necessarily be used buffer in-between the guitar’s top and capsule, so the capsule must be built-in into housing made out of real bone or bone-like material and under some pressure to ensure full vibration capture and transfer;
4. You should avoid attaching the capsule directly to the guitar's top, this way you get too much Lows;
5. The capsule housing (shown on the image below!) has a specifically designed 2-stage top’s surface, the first (highest) provides a direct connection to the guitar’s top while the second, the lower, is used for gluing;
6. The glue: you should use resin glue which, when dried, offers sufficient pickup-to-soundboard tension for the most of sound and vibration transfer;
7. You can even use two identical dynamic capsules (perhaps, more but I got tested two!) wired in-series for doubling the capsule’s output which typically under 1mV;
8. You will have to build specific preamplifier with low impedance input and sensitivity of <1mV;
9. Due to low impedance, you can install this pickup on your instrument passively and use external preamplifier;
10. Even laminate guitars may sound super with these little dynamic capsules…..

This dynamic pickup will make you forget about any other pickup types and models, it is a real pickup-killer….. wishing you patience and luck!

[Mikheil]

Well, enjoy the schematic and finished Mr. Acoustic external 2-channel preamp unit for steel-string acoustic guitar .....

Gain=100
THD=0.002%
Noise=36µV



Full coverage (not in English) is HERE

Just in case, old Oktava MKE-5B (MKE-3) ECM capsules are really great in such applications in the body of acoustic guitars, these old microphones have exceptional and phenomenal brilliant Highs, installed internally they sound as being professionally positioned externally...... and these great mics cost almost nothing.....
However, the dynamic capsules must be selected carefully, no basic rules nor knowledge.....
Good luck!