Mic on the 1st Floor and Speaker on the 2nd

My another photo blog “LQ Laoshi’s Photo Gallery”(outside wordpress)

My family is not wealthy by any means. However, our house, located in suburban, is a little bigger than those houses in urban area. I am always in my room on the second floor, doing PPT slides making for online Japanese teaching. My mom is in her room on the first floor. So when she calls me, she needs to come out from her warm room to cold corridor and shout my name aloud. I had been thinking about if there was any good way for her to call me from her room. I thought of making a device with a microphone, amplifier, long wire, and a speaker.

I bought several electric parts by amazon.co.jp. The solder was the only thing that I needed to go buy in DIY shop.

I forgot to take a photo while I was assembling. The device was finished as in the photo. Voice caught by condenser microphone is amplified by 6-Volt. And the speaker with 77mm diameter sounds at the end of the long wire—–If it could work as I designed. People may say “Oh, you should have arranged those parts a little more left in the box, because there is an empty space.” Yes, I thought the same thing when I finished assembling. But I would say, that empty space on the left will be used, liking it or not.

So I put this device on the cedar column in mom’s room. I wish that this device will not be disturbing when my mom puts the futon down in the night and puts it back in the morning.

My house is a kind of traditional wooden Japanese style building. So it is relatively easy to place a long wire from room to room and make a hole on the wall. This is a photo in my room.
But I found a big PROBLEM with this. The voice on the speaker is too small even in the maximum volume. In Japanese expression, this would be metaphorically said “voice of a mosquito’s weeping”
I know that the amplifier works well because I tested and confirmed that it could make sufficient sound volume before assembling. So the problem is on the microphone unit. The unit does not make enough gain for the signal that is coming from the microphone. I have already sent a question to the vendor through amazon, asking whether or not the mic unit output did not gain a good sound level such that can be connected to amplifier directly. I don’t expect that the vendor can answer my question soon because now is the time of lunar new year.
So I think that I need to add a “pre-amp” between the microphone unit and the amplifier. I will buy a pre-amplifier unit from amazon and place it in that empty space on the left in the box, probably.

Yesterday I went to a DIY shop by walk, to buy solder. On the way I found two swans when I was walking in rice fields area.