Apple "HomePod mini" - Review and frequency response measurement.

I just got the Apple "HomePod mini" as an AirPlay evaluation device. The box was smaller than I had imagined.

HomePod min(2).jpg

I immediately took it out of the box and tried to set it up, but it took quite a bit of time because I had deleted the Home app or turned off Bluetooth.
After I managed to finish the setup, I can play music from Apple Music app without any problem.

So I decided to measure the frequency response of this device by playing sound from iTunes.

It was measured on a table at a distance of 1 meter with "Audio Frequency Analyzer" (AFA) app.

I played a sine wave at 1kHz to roughly adjust the playback level.
Then I played back pink noise and measured the frequency response by AFA app, holding the peak for about 15 seconds and doing a 1/3 octave band analysis.

- FFT measurement (playback level adjustment: 1m, Sine wave 1kHz)

- Frequency response measurement (1m, Pink noise, 1/3 octave band analysis, HOLD on)

In this measurement, the levels at 160Hz and 200Hz were a little low, probably due to standing waves, as they also appeared in other speaker measurements.

For the size of the enclosure, the bass extended well down to 63Hz. The high frequency range above 2kHz was about 2 to 4dB lower than the mid range, and the characteristic sound point seemed to be around 12kHz.

The auditory response was close to this frequency response, and the bass feeling was more than I expected, so it was easy to listen to music even at low volume. I felt that the drivers and passive radiator were well designed for this small size.

The HomePod mini does a very good job of playing music for background music!
posted by toons at 01:17 | Audio


Hand crafted SP with ONKYO "OM-OF101" vol.5 - Extensions

This gimmick is a duct plug!

Cut from a scrap piece of OSB plywood.


I had to cut it out six times in total to fit the diameter of the duct holes. The thing behind it is the auxiliary plate for the tweeter, which is in the process of being painte

Here is a comparative image of bass reflex mode and sealed mode.

- Bass reflex mode

- Sealed mode.

I immediately measured the frequency response of the bass reflex mode and the sealed mode.

They didn't seem to have any extreme differences, but the 63Hz level seemed to be a little lower in the sealed mode.

- Frequency response in Bass reflex mode

- Frequency response in Sealed mode

As a 10.5L sealed box, f0c (f0 of the unit when installed in the box) is calculated around 101Hz, which is a little higher frequency than bass reflex.

My impression is that the bass is a bit suppressed in sealed mode, and bass reflex mode is probably the better choice.

If sealed mode is used, it would be better to add a little more sound absorbing material.
posted by toons at 00:04 | Audio


Hand crafted SP with ONKYO "OM-OF101" vol.4 - Assembly completion and evaluation

The summer heat has subsided and the mornings and evenings are becoming more pleasant.



Get the faston terminals, and the speaker box for the OM-OF101 is complete!


The size image of the box looks like this. The magazine is B5 size.


I installed the SP unit in the completed box and played music at a low volume to check the connections.


Polarity is OK with no unusual noises. First, I measured the frequency response of the left and right channels.


I used the "Audio Frequency Analyzer" to measure the frequency response of the pink noise playback, 1/3 octave band, after matching the level with a 1kHz sine wave.

- frequency response L-ch (Initial)

- frequency response R-ch (Initial)

It is wonderfully flat.

There is no extreme difference between the left and right channels in the low frequency range, so the SP box assembly seems to be fine. The low frequency levels at 63/80Hz are the same, so the duct tuning seems to be good.

Anyway, I listened to some songs in this state.
Instrumental music, female vocals, orchestra, quartet,... I could feel the rhythm of the bass well enough. And the separation of the instruments was sufficient, and the sense of localization was fine.

However, I felt that the sound was lacking something. The vocals did not come forward. I wonder if this is a matter of personal preference...

So I tried reducing the sound absorbing material a little.

- frequency response (reducing the sound absorbing material)

As a result, the 63Hz level dropped a little. The overall impression was the same, although I felt that the volume of the bass might have been reduced in the auditory sense as well.

At this time, the distance between the left and right speakers was about 130cm, which was a little too wide for a 10cm unit.

I narrowed the distance to 90cm and listened again. I felt that the vocals became a little clearer.

So, I measured again for confirmation.


- frequency response (On the axis 100cm, 0 degree)

I measured again at a different angle, 1m above the axis. I attached a 1m long string to the tripod leg and moved it to a 30 degree position.

By using "ClinoScope", I found the angle in one shot just by turning the iPhone.


The frequency response at 30 degrees showed a gentle drop in the frequency range higher than 5 kHz.

- frequency response (On the axis 100cm, 30 degrees)

The reason for the unsatisfying sound may be the high frequency characteristics, or may be a matter of the sound directivity when the space between the speakers is too wide.

I tried to measure the 60-degree response as well, but the sofa was in the way. I had no choice but to measure at 45 degrees for reference.

- frequency response (On the axis 100cm, 45 degrees)

As for this unit design, I felt that the emphasis would be on the low-mid range.

It reproduced enough bass feeling even with a simple bass reflex, and almost no unpleasant sound came out. I would have liked a little more sharpness, but that's a matter of personal preference.

As mentioned in the article on box construction in the magazine, this may be the reason why a box with moderate resonance may be more suitable.

The fact that it is not flavored with a specific frequency range means that it is a seriously designed unit.

It will be interesting to use it as a midrange speaker unit in a 3-way system.

As a future plan, I'm thinking of putting a tweeter on it.
posted by toons at 05:52 | Audio


Hand crafted SP with ONKYO "OM-OF101" vol.3 - painting

The temperature has dropped in September, and it feels a bit like autumn.

While I was waiting for the purchase of parts, I varnished the speaker box. (Really be satisfied with the way it looks?)


I lightly painted the back plate with black spray. This was only one coat of paint, so it was done in an instant.

The only remaining step is to install the terminals and the unit.
posted by toons at 18:24 | Audio


Hand crafted SP with ONKYO "OM-OF101" vol.2 - assembly

Today is usually the last day of summer vacation for children.

Some areas have extended the summer vacation for COVID-19, so it will be hard for parents and teachers to take care of them.

I've been working on assembling the speakers since last weekend.

It's a simple bass-reflex structure, so it's easy to assemble in order, but there are a lot of difficulties due to the lack of precision in cutting by amateur.

The first step is to attach the auxiliary reinforcement plate and duct plate to the baffle plate.


The duct board is screwed so that it can be adjusted later.

Glued the diagonal side panels and side panels on both sides of the baffle board.


There is still a gap at the diagonal cut point. It may look like a straight cut, but it's probably slightly crooked. When the bond is dry, fill in the gaps with wood putty.


Install the back plate.


Lightly fill it with sound-absorbing material.


The back plate is made of the same size plate screwed together so that it can be adjusted later.


This is what it looks like when the back plate is attached.


Glue the top plate.


Due to poor cutting accuracy, the diagonal side panels and the top panel were out of alignment. If I get motivated later, I will try to adjust them by planing.

The box volume is about 10.5 liters, and the tuning frequency of the duct is calculated to be about 75Hz.

This is a little larger than the example and recommended box, and the duct frequency is lower, so I hope it will produce a relaxed bass sound.

After preparing the speaker terminals and the speaker unit, I found out that I didn't have any Faston 250 terminals in stock! Have to buy some.

As a result, this speaker craft will not be completed until after this weekend. So, I may try painting it with water-based varnish.
posted by toons at 13:06 | Audio


Hand crafted SP with ONKYO "OM-OF101" vol.1 - prologue

The long rains during the summer vacation are finally over. I was hoping that the weather would become a little more like autumn, but the heat of summer has returned once again.

I got the ONKYO "OM-OF101" speaker unit, so I designed the box image, did a rough calculation of the capacity and ducts, and managed to make a cutting diagram of the wood, but ... I didn't feel like cutting in this intense heat.


With the SDGs in mind, I tried to make effective use of leftover scrap wood as much as possible. I used leftover shelf boards for the bottom panel, OSB plywood left over from DIY for the baffle, and scrap MDF for the rest. The only thing was to get four pieces of MDF (300x300mm) for the backing board.

Just looking at the blueprints didn't help, so I made up my mind to start the cutting work!

Taking care not to disturb the neighbors with noise, I started work at 11:00. I finished all the cutting work in about two hours.

I took my time to cut the diagonal cut carefully, so I was able to get good accuracy. However, the last part of the work, drilling the square holes in the back plate (for adjusting the ducts and sound absorbing material) with a jigsaw, was a bit of a pain.


It looked squishy in the picture, and I felt like I've run out of energy here. I was sweaty at the limit of my strength. This was not a place to be seen, so I left it like this.

Finally, it is an image of the OM-OF101 mounted on the OSB plywood baffle.


After a while, I'd like to do the assembly in a cooler place.
posted by toons at 19:47 | Audio

New updated - "Audio Tone Generator - ATG" ver 6.0


"Audio Tone Generator - ATG" has been updated to ver 6.0 today.

"Audio Tone Generator - ATG" is a powerful reference Audio test signal generator app for iPhone.

It creates the reference audio test signals as Sine wave, Sweep signal, Chirp signal, White Noise and Pink Noise, and has a frequency accuracy of 0.1Hz.

In addition, it can generate octave band noise of 1/1 or 1/3 octave in NOISE mode. You can also use it for detailed analysis of specific frequency bands.

In the latest version, chirp signal generation and preset frequency customization functions have been newly added.

In the latest version, the UI design has been revamped, and the chirp signal generator and preset frequency customization are now available.

- Sine wave : 8000Hz

- Sweep signal : 20Hz - 20000Hz

- Chirp signal : 100Hz - 16000Hz

- White noise

In addition, it can generate octave band noise of 1/1 or 1/3 octave in NOISE mode. You can also use it for detailed analysis of specific frequency bands.

- Octave band noise : Pink noise , 1/3 octave band , center frequency 3150Hz

You can also customize the preset frequencies in sine wave and sweep signals. You can set buttons for frequently used frequencies.

- Preset frequency setting example (sine wave)
atg_sine_preset_2.png atg_sine_preset_2_v600.png

This app can be very useful for a variety of applications including:
- Testing for Loudspeakers and Headphones
- Burn-in for Audio equipment and Loudspeakers
- Testing and tuning for Audio amplifiers, Equalizers and many other Audio equipment.
- Acoustics testing
- Frequency response measurement for Audio systems using White noise and Pink noise
- Sound Masking
- Relaxation and Meditation
- Hearing Test
- Mosquito sound creation for teenagers

If you are interested in this app, please click the following link to display on the product information of App StoreTM.

posted by toons at 04:47 | News


Got ONKYO OM-OF101 full range speaker unit!


I got the ONTOMO mook No.12 magazine with ONKYO "OM-OF101", 10cm full range loudspeaker unit as a supplement.

It's a pity that it was released at a time when the summer vacation is almost over.


This unit uses a technology called biomimetics. According to the article by the speaker unit developer, they traced the wings of a dragonfly.

It looks a little weird in the picture, but it doesn't look that bad in the actual unit.


Comparing it to FOSTEX FE83 that was lying in the corner of the room, it shows the size of the unit diameter and magnet size. The weight of the unit was just under 800 grams, which seems to be a lot more than the 565 grams of FOSTEX FE103NV.


What kind of SP box should I build for this unit?

I'm going to try the orthodox bass reflex system, but looking at the units, I think a slightly larger sealed system might also work.
posted by toons at 12:28 | Audio


Animated clouds!


Huge rain cloud seen in the eastern sky from in front of Nijo Castle!

It looks like an animated cloud.


To my eyes, it looked like a big bird spreading its wings over the main cloud.

It was just a clear day in Kyoto, so I was very impressed by these fuzzy clouds.


When I checked the rain cloud radar, I found that it was a huge guerrilla cloud. The timing was about 15 minutes before the radar image, so it must have been moving north around Otsu City.

If its course had shifted even a little to the west, Kyoto City might have been hit by a heavy downpour.
posted by toons at 19:51 | diary

Switch from mice to trackball - Logitech "ERGO M575"


I quit using a mice and switched to a trackball.

- Logitech "Wireless Trackball ERGO M575 "


Eco-friendly packaging, just wrapped in a bit of thick paper!


Only warranty card included, no manual.


The ball looks like this!

It came off easily when I lightly pushed it out through the hole in the back. The ball was 34mm in diameter and weighed 26g.


3-point support, optical sensor in the center.


Inside the battery box, a Unifying receiver. It can be connected wirelessly via this USB receiver or Bluetooth. It runs for about two years on alkaline batteries.


I've been using a ThinkPad USB laser mouse for my desktop PC.


Two years ago, I updated my keyboard to a Filco Majestouch NINJA Tenkeyless, and I've been using this mouse for a while, but...

I've been having trouble with the pain in my wrist and forearm lately, probably due to tendinitis.

I thought I should get a more physical-friendly device, so I chose the Logitech ERGO M575 trackball!


I am very grateful that I no longer need to put a mice pad on my desk, which gives me more desk space.

It allows me to access the trackball, click switches and scroll wheel by simply placing my palm over it. It is a good design that fits our hands.


I just put my right hand on it, and I can operate it without moving my wrist at all, which is very comfortable.

Using the trackball with my thumb takes some getting used to, but I'm going to try my best to get used to it.
posted by toons at 18:27 | PC