2024/03/28

Handcrafted speakers using Wavecor's full-range speaker unit "FR085CU03" Vol.5

計測風景a.jpg

Let's measure the frequency response with pink noise using "Audio Frequency Analyzer" iPhone app.

First, I measured only the main cabinet after sound aging.

特性_キャビ(エージング)a.PNG

It seems to be different above 10 kHz than immediately after assembly, but it may have been slightly off axis when I first measured it. In the low-frequency direction, the peak at 160 Hz seems to have dropped and the damping has become smoother.

Next, I joined the main cabinet and the legs and measured the results:

特性_組上a.PNG

The 80-100Hz frequency range was increased, and the 50-63Hz frequency range was also slightly increased.

Originally, I thought that the main cabin was designed as a bass reflex and the legs were an extension of the duct, but the main cabin is 1.2L and the legs are about 2.5L, both doubling the volume to 5L, so it seems to be operating as a double bass reflex.

If I assume a double bass reflex, I can roughly calculate fd1=81Hz and fd2=66Hz, but I will have to check the impedance characteristics to see if it is working as it should.

Next, let's change the elevation angle and see how much the high-frequency characteristics change.

With the main cab fixed at the measurement position, the elevation angle is 0°, 15°, 30°, 60°, 90°, and so on. The elevation angle was measured using "ClinoScope - Dynamic Inclinometer and Gyroscope" app.

- Elevation angle: 0 degree
仰角(0度)a.jpg

仰角(0度)PN特性_L_a.PNG

- Elevation angle: 15 degrees
仰角(15度)a.jpg

仰角(15度)PN特性a.PNG

- Elevation angle: 30 degrees
仰角(30度)a.jpg

仰角(30度)PN特性a.PNG

- Elevation angle: 60 degrees
仰角(60度)a.jpg

仰角(60度)PN特性a.PNG

- Elevation angle: 90 degrees
仰角(90度)a.jpg

仰角(90度)PN特性a.PNG

The 15 degrees elevation angle had a flat characteristic. At an elevation angle of 30 degrees, the area around 12 kHz dropped. At 60 degrees and 90 degrees elevation angles, the characteristic gently dropped above 6 kHz.

The unit is probably designed so that this characteristic can be obtained by setting the speakers at a 15 degrees left-right angle. If the distance between the left and right speakers is 120 cm, I should be listening at about 220 cm from the speakers.

Now let's talk about the sound quality.

I had imagined a soft sound like that of ScanSpeak from its appearance, but the response is much faster and tighter than I expected, and the mid-high range is free from muddiness and distortion, probably due to the effect of the 10cm square cab.

The tendency of this SP system is overall sharp sound quality with not much volume on the low-frequency side. The rise and fall of the sound is fast, and the drum snare and guitar picking can be felt realistically.

The baffle area is small, so the center localization of vocals seems to be well contoured. I had underestimated the sound of this unit, but it is quite to my liking. If I had the budget, I would like to use it for the mid-highs of a multi-system.

This upright biped (not walking) type is quite unstable when it is installed with elevation adjustment and leg removal during measurement work.

It would be vulnerable to earthquakes, and from a safety standpoint, it would be better to fix it to the pedestal.

Since there were no boards of appropriate size, I gathered boards of about 300 mm in width and fixed them with wooden screws.

台座(1)a.jpg

台座(2)a.jpg

In the future, I will be listening to a variety of different sound sources for sound aging.
.s
posted by toons at 23:58 | Audio

2024/03/24

Handcrafted speakers using Wavecor's full-range speaker unit "FR085CU03" Vol.4

メインキャビ(エージング)_2a.jpg

I did sound aging of the main cabinet for one day.

This alone gave me a fairly tight bass sound because of the rigidity of the dice-shaped cabinets.

The duct opening area is small, so I was worried about whether the bass reflex operation would work properly, but it seems that air vibrations are passing through.

The baffle is also small, so the center positioning of vocals and other sounds is perfect.

Finally, the main cab and the legs were assembled.

合体(1)a.jpg

Since the opening diameter of the cylindrical duct and the leg is set just barely, it took a lot of force to fit them together. The joint was successfully completed.
 
Rise up, Gundam!

合体(2)a.jpg

Or rather (if it is reddish), the 7th Apostle or Ideon. The activation of the Ideon, which could mean hope or disaster...

設置(1)a.jpg

As a gimmick in this time, the joints of the legs are not glued so that the elevation angle of the main cabinet can be changed.

When the unit axis is aligned with the ear as about 45 degrees:

仰角(1)a.jpg

Also upward and deformed robot-like sound field type:

仰角(2)a.jpg

As an example of a sound field type installation:

設置(2)a.jpg

In the next issue, I would like to finally start measuring system characteristics.
.s
posted by toons at 23:58 | Audio

2024/03/22

Handcrafted speakers using Wavecor's full-range speaker unit "FR085CU03" Vol.3

Just when I thought it had warmed up, it's back to winter mode again, and the rain continues, making for a depressing week.

Last weekend, I began the painting work.

塗装後(1)b.jpg

During the leg work, the weather was still cloudy, so I was able to take time to dry the paint and get a good coat of paint,

However, when it rained during the main cabinet work, the top coat was applied without drying properly, resulting in an uneven paint job.

塗装後(2)a.jpg

It is especially conspicuous because it is white.
However, the paint is running low, so I gave up for now. I will polish it with sandpaper later.

After getting myself together, I installed the electrode terminal and Wavecor unit "FR085CU03" in this state.

ユニット取付(1)a.jpg

The flange-like restraints on either side are stoppers for leg mounting.

ユニット取付(2)a.jpg

Before installing the legs, I did a sound check with just the main cabinet to check the wiring.

It sounded fine. The full range has no major problems as long as the positive and negative wires are wired correctly.

Since it was a good opportunity, I measured the frequency response with pink noise using "Audio Frequency Analyzer" iPhone app.

First, I used FOSTEX "FE83E" as a standard for comparison.

計測(FE83)a.jpg

This is a very old unit, but the frequency response is like this:

特性(FE83)a.PNG

There was a level difference between 2kHz and 2.5kHz, but the midrange was flat and gently characterized.

Under the same measurement conditions, Wavecor's FR085CU03 showed the following:

計測(FR085CU03)a.jpg

The high frequency range drops from about 8 kHz and peaks at 20 kHz, as shown in the manufacturer's published frequency response.

特性(FR085CU03)a.PNG

200Hz-2kHz is nicely flat.

The peak at 160Hz is probably a characteristic of the cylindrical duct. The duct resonance frequency should be around 70Hz, but the small diameter of the duct may be making it operate in a sealed manner.

After aging the main cabinet for a while by playing various sounds with just the main cabinet, I will join the legs and see if the characteristics change.
.s
posted by toons at 23:44 | Audio

2024/03/17

Handcrafted speakers using Wavecor's full-range speaker unit "FR085CU03" Vol.2

After replenishing the missing materials last time, I unexpectedly injured myself. I also suffered a slight backache due to walking while protecting my leg.

Undaunted, I started the assembly work.

Attach the side and bottom plates to the unit mounting plate (100x100mm). At this point, the cylinders that penetrate the side panels are not glued yet, but merely positioned. A hole of Φ12mm is drilled in the center of the cylinder. The cutting is dirty, but it will not be visible once the box is closed.

The speaker terminals will be to come out from the bottom plate.

メインキャビ構造.jpg

The sound-absorbing material was wrapped around the backboard section and the excess around the cylinders.

メインキャビ吸音材.jpg

At this point, the cylinder was fixed with disks on both sides.

The next step was to make the legs, the same shape for four sets. They are 600 mm high, 60 mm wide, and 147 mm deep.

脚部構造(1).jpg

The thickness of the board is 12 mm.

Assembling is not difficult, as the front panel is attached to the side panels, top panel, bottom panel, and side panels, in that order.

However, due to an error in the board removal calculation, the back plate of the legs could not be removed from the same MDF material. I had no choice but to use 10mm-thick cedar for the back plate only.

The way the reinforcement was inserted also looked ugly. It is okay because it will be well hidden inside.

脚部構造(2).jpg

Sound absorbing material has been lightly applied inside the front.

I expect the main cabinet (although the duct location will be on the back side) and the legs to be side by side and styled like this. I've attached 5.5mm MDF to the front and rear boards of the main cabinet and cut them diagonally with a planer. I think it will look a little better.

全体構造.jpg

Assembly is now almost complete.

組立完成(1).jpg

It was larger than expected for an SP system with a 4-inch speaker unit.

組立完成(2).jpg

Next I plan to paint it and finally join the main cabinet and the legs. (to be continued in the next issue)
.s
posted by toons at 20:56 | Audio

2024/03/12

Handcrafted speakers using Wavecor's full-range speaker unit "FR085CU03" Vol.1

It has been more than a month since we obtained the Wavecor "FR085CU03" unit, and while looking at it, I could not come up with a good idea of what to do with it.

One day, I stopped by a local home improvement center and while rummaging in the lumber section, I found a cylindrical piece of lumber like the one in the photo below. I decided to try using it for ducts, so I immediately bought it!

ダクト用円筒a.jpg

Size: length 200 mm, outer diameter about Φ25 mm, inner diameter about Φ13 mm

Assuming a cavity volume of 1.2L, I roughly calculated that fd=70Hz and f0c=140Hz.

A simple small bass reflex would not be interesting, so I tried to come up with a design image of a cylindrical duct that would penetrate the side panel of the cavity and be supported by something on both sides of the duct.

After finishing the approximate design, I cut the boards and wood.

メインキャビ部材a.jpg

Component for one channel of the main cab, with outer diameter dimensions 124mmx124mmx148mm, capacity approx. 1.2L

Holes are drilled in the left and right side panels to penetrate the duct cylinder.

Later, I plan to drill a hole of about 10 mm in the center of the duct cylinder.

Next, while cutting the legs that support the left and right sides, I realized that I had only bought enough MDF for one side.

脚部部材a.jpg

This picture is for one channel. I didn't draw the planking drawings properly, so I thought I only needed two sets of front and rear plates, side plates, and top and bottom plates. Assumption is a scary thing.

I had to run to the home improvement center again, and the expense was too much. I had to be calm before I started the production. (To be continued in the next issue)
.s
posted by toons at 17:56 | Audio

2023/12/21

Get special full-range speaker units, Wavecor's "FR085CU03".

表紙.png

A special book (Ontomo Mook, a separate volume of STEREO magazine) with a supplement of Wavecor's "FR085CU03" speaker unit, which I thought would not be available this year, arrived today, just before the end of the year!

I have to admit that I had never heard of Wavecor before, but it says that the company was founded in 2005 in Guangzhou, China.

It seems that Wavecor was founded by a Danish design engineer who had been working in Denmark since 1983.

Let's take a quick look at what's inside.

内容.png

In previous mook books, the speaker units were packaged in plastic bags, however, in this book Wavecor's "FR085CU03" units are packaged directly in a bare cardboard box.

The actual unit is matte black and looks heavy, although it looks glossy in the photo. The diaphragm seems to be made of aluminum.

ユニット(表).png

On the back side, specifications are written in Japanese. Holding it, I thought it was heavy for a 6cm speaker unit.

ユニット(裏).png

Speaker unit specifications are transcribed from the paper.

# Wavecor "FR085CU03" Specifications
Impedance: 4Ω
RDC (electrical resistance): 3.45Ω
SPL (Sound Power Level): 86dB (2.83V/1m)
Fs (lowest resonance frequency): 114Hz
Sd (diaphragm area): 21cm2
Vas (recommended volume): 0.61L
Mms (diaphragm weight): 2g
Qms (electrical resonance): 13.1
Qes (mechanical resonance): 0.94
Qts (overall resonance [Q0]): 0.87
Bxl: 2.3
Rms: 0.11Ns/m
NOM Power (continuous input): 10W
MAX Power (maximum input): 20W

I am going to enjoy myself over a drink and consider what kind of
.s
posted by toons at 23:47 | Audio

2022/10/01

Loudspeaker using MarkAudio "OM-MF4-MICA" - part 4 - Listening impression and measurement

04.密閉(2).JPG

First, I adjusted the 250 Hz peak when combined with the lower cabinet. However, I only had to add a little sound-absorbing material in the middle of the duct.

Since I did not have a proper sound absorbing material on hand, I substituted aquarium filter mat. The material was probably polypropylene, 8mm thick. The only place to put it in was at the first fold, and I just pushed it in from the duct entrance.

First, I compared each frequency response. The results of the measurements with the "Audio Frequency Analyzer" are as follows (without sound absorbing material = upper figure, with sound absorbing material = lower figure).

01.吸音材.PNG

As expected, the one with sound absorbing material was about 2dB lower at 250Hz. If the amount of sound-absorbing material is increased, it should decrease even more.
However, it might block the sound path, so I left this one piece alone.

I finally got around to listening.

Usually I play CDs that I have on hand and listen to them as I go along, but this time I had to hear how the different methods would change the sound.

I used a sample CD from the January 2011 issue of Stereo magazine.

This time, I chose classical and jazz from these recordings because I wanted to hear the difference especially in the low-frequency direction.

 12. Saint-Saëns: Symphony No.3 "Organ Symphony"
 13. Ornette Coleman: Bird Food/Trissonique

The left-right spacing was about 1 m, and the listening position was about 2 m away from the SPs. Sealed and both bass reflexes were performed with TAOC stands, and the acoustic maze was placed on the lower cabinet.

02.試聴(1).JPG

02.試聴(2).JPG

The sealed system is designed to be used on a desktop, with the ducts blocked by a board. For the bass reflex (upward-facing) system, the board was shifted so that the duct would be open.

The feeling of each method was as follows.

- Sealed box:
03.密閉.JPG

The timpani percussion was light, and it was difficult to hear the descending part of the organ scale. Although I could hear the pitch of the bass, the sound of the strings hitting the fingerboard seemed louder.

- Bass reflex (upward-facing):
03.バスレフ(下).JPG

The timpani percussion was rather audible. The organ scale was also not well resolved. The sound of the fingerboard still seemed to resonate.

- Bass reflex (downward-facing):
03.バスレフ(上).JPG

The timpani percussion became more prominent and the tutti was more powerful. The volume of the wood bass could be felt.

- Acoustic Maze:
03.音響迷路(BH).JPG

The scale of the orchestra sounded a whole lot larger. I could hear the pitch of the organ. The bass guitar sounded more powerful.

Since this is just a subjective impression, I measured the frequency response of each piece.

I set up the iPhone at the listening position (1.8m, about 15° to the loudspeaker) with the left channel only, played a song, and checked the frequency response with peak hold.

Before that, I examined the characteristics of the music source itself with "Music Frequency Analyzer". This application can digitally analyze ripped music data. The following result is a peak-hold analysis of the frequency response of the entire music source.

04.オルガン付き.PNG

"Organ Symphony" was nicely smooth over the entire frequency range.

04.バードフード.PNG

"Bird Food" was recorded at a fairly high level in the 63-250 Hz range.

If the frequency response of this sound source could be reproduced well in a listening environment with speakers, it would be the reproduction of the original sound. However, in practice, I think it is quite tough.

The actual measurements for "Organ Symphony" were, from top to bottom, sealed box, bass reflex (upward facing), bass reflex (downward facing), and acoustic maze.

05.実測(オルガン付き).PNG

With the sealed box, 125-200 Hz had a reasonable sound level. With the bass reflex (upward), the same band seemed to be emphasized.

With the bass reflex (downward), the 160 and 200 Hz frequencies dropped slightly and the energy shifted to the 100 and 125 Hz frequencies.

In the acoustic maze, 100 Hz rose further and 80 Hz rose by 6 dB.

The same trend was observed with the "Bird Food." The 160 and 250 Hz frequencies in the bass reflex (upward) were at more stronger level.

05.実測(バードフード).PNG

# Ignore the frequencies of 20Hz and 31.5Hz as they are external noises such as automobile noise.
# A line was drawn later between 80Hz and 100Hz to make it easier to see.

I expected the acoustic maze system to improve down to about 63Hz, but as far as the characteristics are concerned, it came up a little short.

I was hoping for a little more at lower frequencies, given the combined system size of the top and bottom. I thought it was necessary to either extend the sound path further or switch to a double bass reflex system.

This time, I focused on how the low-frequency characteristics changed depending on the type of system.

I thought it was not necessary to emphasize bass so much for a desktop installation. I found that this unit has sufficient reproduction ability even with sealed or bass-reflex systems.

After that, this system should be flipped upside down or duct blocked depending on the sound preferences and the genre of music. For serious listening, the unit should be placed on the lower cabinet. It may be a little troublesome.
.s
posted by toons at 10:08 | Audio

2022/09/27

Loudspeaker using MarkAudio "OM-MF4-MICA" - part 3

Custom speaker stands made for MarkAudio "OM-MF4-MICA" can be transformed into various SP systems depending on the setting with the main speakers.

- Main SP (Bass reflex port on the underside)
01.バスレフ(下)_1.JPG

First, I measured the frequency response of a small bass reflex with only an upper cabinet.
To keep the same conditions as much as possible, a gap duct was secured by sandwiching a single board over the lower cabinet.

01.特性バスレフ(下).PNG

The 100-160Hz frequency response is higher than that of the TAOC cast iron speaker stand, but this may be due to aging. I think the frequency response is not so bad.

- Main SP (above the bass reflex port)
02.バスレフ(上)_1.JPG

Next, the upper cabinet is turned upside down. Due to the central placement of the unit, the front view was almost the same. The ducts were now on the top panel side and about 5 cm longer.

02.特性バスレフ(上).PNG

The frequency response has shifted from a peak of 100-160Hz to 160-200Hz.
The calculation was about fd=240Hz. If it is placed on a desktop, it may be swapped up or down depending on the music.

・Main SP + SP stand (BH)
03.BH_1.JPG

Finally, the upper cabinet was connected to the lower cabinet to see how low frequencies could be reproduced.

03.特性BH(1).PNG

Oops, a peak was measured at 250 Hz in 1/3 oct-band response.
A wave of 234.5 Hz was output, which was the calculated resonant frequency of the lower duct. It was indeed functioning as a resonance tube.

In advance, I was thinking that it would not work as a horn because the upper cavity volume is large for a back-loaded horn, and the throat area is also quite large and the aperture is small.

Compared to the bass reflex system, the 100-160Hz level is about the same, and the 40-63Hz level is slightly higher, possibly due to the quarter-wave effect.

I will work on the 250Hz peak later, but this time I turned the lower cabinet upside down.

- Lower cabinet flipped upside down
04.密閉(1)_1.JPG

The bottom panel did not have duct connection holes, but it had a reinforcing plate the same size as the top panel to allow the upper cabinet to be placed on it. When the upper cabinet was placed on top, it was also perfectly merged.

- Main SP (sealed type)
04.密閉(2)_2.JPG

This changed the upper cabinet from a bass reflex operation to a sealed system.

04.特性密閉(1).PNG

The frequency response was not a steep drop in the low-frequency part like a bass reflex, but a gradual drop below 100 Hz. The f0c calculated as sealed was 137.5Hz.

I have measured the frequency response of each of the four ways of use. I thought I had approximately the behavior and characteristics I had in mind for each method.

I was concerned about air (sound) leakage from the connection point between the two cabinets, but the measurement results did not seem to indicate any significant leakage.

In the next issue, I would like to report on the audition and consider the countermeasure for the 250Hz peak.
.s
posted by toons at 02:36 | Audio

2022/09/25

Loudspeaker using MarkAudio "OM-MF4-MICA" - part 2

I have prepared a custom speaker stand specifically matched to the MarkAudio OM-MF4-MICA speakers!

This speaker stand has a height of 462mm. When the main cabinet is placed on it, the front height is 662mm (562mm to the center of the unit).

01.キャビ(L).JPG

There is a hole on the top surface. You can also see a hole on the lower back side.

02.キャビ(裏).JPG

Now let's place the main unit with the unit attached. It fits perfectly.

03.SPシステム.JPG

Actually, this speaker stand has a horn structure.

04.組立(4).JPG

Even though it is a horn structure, the sound path is not that long.
The lower cabinet alone is about 1400 mm long. Thus, it has characteristics intermediate between CW horns, resonance tubes and acoustic labyrinths.

When combined with the upper cabinet, the structure is as shown in the following picture, and the sound path together with the duct in the upper cabinet is 1450 mm long in total.

05.組立(6).JPG

If think of a resonance duct as [speed of sound / length of sound path], I get

340 m/s ÷ 1.45 m = 234.5 Hz.

For your reference, here is a photo of a board-cutter.

06.板取(2).JPG

This also only needs to be laminated to the side panels in the order of the sound path, so the production time is about 3 hours. It is important to note that the spacing of the boards dividing the interior must be matched.

In the next issue, I would like to introduce the amazing features of this SP system along with the measurement results.
.s
posted by toons at 19:22 | Audio

2022/09/22

Loudspeaker using MarkAudio "OM-MF4-MICA" - part 1

MarkAudio "OM-MF4-MICA" is a 6cm unit, so I decided to make a small bass-reflex system.

To make it small enough to be placed on a desk, I designed it to be 12 cm wide, 15 cm deep, and 20 cm high.

01.板取(1).JPG

The small number of boards made cutting easy, and production was not difficult since the boards are laminated to the side panels one after the other.

02.組立(1).JPG

At the time of temporary assembly, the duct direction was toward the unit, but I wanted to increase the duct length a little more, so I changed the direction to face the back plate.

03.組立(2).JPG

The bottom plate had a 12 mm gap to allow the bottom duct to exit to the back plate side.

04.組立(3).JPG

The bottom plate had a 12mm gap and the content area is about 1.9L. The duct frequency (fd) calculation assumed about 170 Hz.

A little sound-absorbing material was added to the top board side, and the side panels were attached to complete the project.

05.完成(正).JPG

06.完成(裏).JPG

I waited a day for the adhesive to dry and measured the characteristics. The measurement location changed from before, so I made a comparison with my standard FOSTEX FE83N SP system.

08.FE83N.JPG

With pink noise playing, amp volume at the same position, and measurement 100 cm on the iPhone axis,
The frequency response measured by the "Audio Frequency Analyzer" app was shown below.

・OM-MF4-MICA
07.特性(OM-MF4-MICA).PNG

・FOSTEX FE83N
09.特性(FE83).PNG

The mid-high frequency characteristics of the OM-MF4-MICA were wonderfully flat, and above 16 kHz was the character of Mark Audio.

That would be expected to be flat with a frequency response at a 30 degree angle.

The duct frequency was probably around 160Hz based on this characteristic, and it looked 100Hz-12.5kHz flat.

The FE83N system seemed to have a slightly higher level at 1k-2kHz.

My impression of the OM-MF4-MICA system was that it did not have the typical papery sound. The high frequencies of cymbals and flutes were nicely diffused, and the graininess of the piano was also apparent.

However, the fundamental sound of the double bass and orchestral tutti reproduction were tough. If the speakers were installed closer to the wall, a little more low end extension might be expected.

So, I guess the only work left to be done is painting.

To be continued in the next article.
.s
posted by toons at 21:29 | Audio