Help with Velleman super stereo ear minikit upgrades

[PCPattyPat14]

Hi all,

I am trying to help my extremely hard of hearing grandfather hear better. His aids dont work all that well for him and are thousands of dollars. I am very new to electronics but have put together a "velleman super stereo ear minikit" (https://www.amazon.com/Super-Stereo-Ear-MiniKit-applications/dp/B0006HJSLE) for him and he loves it! He finally has been able to listen and participate in conversations and even brings it to church to hear the preacher.

I would like to improve this design in a couple of ways and I was hoping to get some input from the folks of this forum.

My first upgrade I want to do is very simple and straight forward of extending the microphones off of the PCB board so that they can be directionally pointed where they are needed. That should be pretty simple. The next upgrades I want to do, are a bit more complex and I am looking for input with.

1. Would it be possible to wire 2 vellemans together to be able to utilize 4 microphones? or is this not worth it?
2. Are there any other better microphones I could substitute the ones given in the velleman kit? Im happy with performance, just wondering if there might be something better out there. are there any other parts I should maybe substitute?
3. Would it be possible to make this into a bluetooth transmitter so that we can cut the cord? I have done a good amount of google searching and really only see solutions for DIY bluetooth receivers. not the other way around. If its not all that simple, I was thinking of just plugging this guy into the kit (https://www.amazon.com/gp/product/B01EHSX28M/ref=ox_sc_act_title_4?smid=A2KUZVNQ9LP7N9&psc=1) but then it would need to be charged separately (better yet maybe powered by the kits power supply?)


Any insight anyone could provide would be greatly appreciated! I am doing this for my grandfather, but it is a fun DIY project for me as well. My background is in Mechanical/industrial engineering so please bear with my ignorance on the topic of electronics, but I am a fast learner! I am also open to any other suggestions you experts might have.

attached is the schematic for the kit


Thank you -

 

[audioguru]

I have normal for my age (73) high frequency hearing loss. The loss is shown on a graph on the web and a free hearing test showed it. I was given free demo hearing aids for one month and I loved them so me and my government senior's grant bought them. My hearing aids are programmed to boost the high frequencies perfectly to match that loss which is more than 100 times at the highest frequency. Low frequencies are boosted only a little.
The Velleman kit boosts all frequencies only 50 times which would overload my hearing with low frequencies and not boost the high frequencies enough.

There are no speakers on the Velleman kit, instead they are electret microphones and they pickup sounds all around. They are not directional so adding two more will make the sound the same as now.
My hearing aids have 4 directional microphones (left front, right front, left rear and right rear) and when set to the "Voice Mode" they automatically switch on only at the direction of the nearest person talking, reducing background noises. On this setting background noise all around is additionally is cancelled.
On the Music Mode setting the automatic switching and noise cancellation is turned off.

The hearing aids have a setting for extra sensitivity that is handy for me to hear faint sounds that normal hearing cannot hear. They also have a Mute Mode where they are turned off and I use it when a motorcycle with no muffler blasts past me. My hearing aids "talk to each other" with Bluetooth so directionality works and I set one and the other does the same. I hear a telephone in both ears.

I could have made hearing aids that do most of the features of the hearing aids I bought but my design would be huge like the Velleman kit and mine would use pretty big batteries that do not last long. My hearing aids are tiny and use a button battery in each one that lasts a long time.

You should take your grandfather for a free hearing test and free demo hearing aids. My demo had the high frequencies boosted only a little at first so that they didn't overwhelm me, then more boost was added each week. Look into what your government pays for that helps seniors.

Here is the graph of "normal for age" hearing loss:

 

[AnalogKid]

My first upgrade I want to do is very simple and straight forward of extending the speakers off of the PCB board so that they can be directionally pointed where they are needed.

Do you mean microphones?

1. Would it be possible to wire 2 vellemans together to be able to utilize 4 microphones?

Why?

ak

 

[PCPattyPat14]

AnalogKid I did mean Microphones. Sorry about that!

I was thinking of wiring 2 together with the trivial thinking that 4 mics are better than 2, but with audioguru 's response ("They are not directional so adding two more will make the sound the same as now."), it sounds like that will not do anything for me.

audioguru I will have to check out where I can get a free demo the next time I am with him. I live in Denver and he is in Indiana, so we dont see each other as much as we would like.

I mailed him the unmodified velleman kit after I put it together a couple weeks ago and he really seems to enjoy using it more than his current hearing aids, which Im sure aren't as savy as audioguru 's. His hearing loss might be a bit different than normal too since he has severally damaged it shooting his gun in the Army without ear protection.

I appreciate the responses, any further insight or ideas are appreciated!

 

[AnalogKid]

Consider replacing the microphones with something more directional. Here are two candidates from Digi-Key that should work if the pin spacing is ok.

CMR-2747PB-A CUI Devices | Audio Products | DigiKey

Order today, ships today. CMR-2747PB-A – 100 Hz ~ 20 kHz Analog Microphone Electret Condenser 2 V ~ 10 V Noise Cancelling (-47dB ±3dB @ 94dB SPL) PC Pins from CUI Devices. Pricing and Availability on millions of electronic components from Digi-Key Electronics.

www.digikey.com

CMC-6015-47P CUI Devices | Audio Products | DigiKey

Order today, ships today. CMC-6015-47P – 100 Hz ~ 20 kHz Analog Microphone Electret Condenser 2 V ~ 10 V Unidirectional (-47dB ±3dB @ 94dB SPL) PC Pins from CUI Devices. Pricing and Availability on millions of electronic components from Digi-Key Electronics.

www.digikey.com

ak

 

[PCPattyPat14]

AnalogKid - Thanks! I think I will get both. Pin spacing wont be an issue as I plan to solder some "2 Pin Screw Terminal Block Connectors" (like these that I have laying around - https://www.amazon.com/gp/product/B07QRHJ489/ref=ox_sc_act_title_2?smid=A37QXIKGEOBCOK&psc=1). Then I will just use some 22 gauge wire to connect the mics to the terminal blocks. Allowing me to raise and point the mics where I want and also the ability to interchange and test these different mics with out having to remove solder.

 

[audioguru]

The "noise cancelling" mic does not cancel noise. Instead it just cancels low frequencies from all directions. For people with normal hearing it will sound "tinny".
The directional mic reduces mid-frequency sounds only a little from the rear, not much reduction at the sides.

Since microphones have a very low output level then their wires can easily pickup mains hum and other interference. Their wires must be very short or a shielded audio cable (coax) should be used.

 

[PCPattyPat14]

Since microphones have a very low output level then their wires can easily pickup mains hum and other interference. Their wires must be very short or a shielded audio cable (coax) should be used.

Great advice! I will try to keep them as short as possible. Would something like this work? https://www.showmecables.com/standa...btF8ueWdlZPZs8YC7FphtPepauEhKNuhoC2pkQAvD_BwE

 

[audioguru]

The electret mic is not balanced like a professional dynamic one (coil and magnet like a mini speaker) so 2 wires inside a shield is not needed, the shielded cables with RCA plugs that come with every audio product can be used. I tried Radio Shack cables but they were too expensive and were the same garbage that is sold at the Dollar Store for a fraction of the Radio Shack cost.