OSAKA High-end Audio Show 2019


I went to Osaka High-end Audio Show 2019 last weekend.

After 16:00 on Friday, each listening room was full and most of them seemed to be in their 50s and 60s.

This year, the venue was only the Hearton Hotel Shinsaibashi, so it may be because people were concentrated.



The Bayz Audio's gCouranteh speaker was very interesting, with a very large and unique pipe shape.


The Burmester amplifier, which was placed in a corridor in the hallway, was created a strong presence. (Is the power amplifier's top-plate flat for listening equipment?)



As an audio sound, I was impressed that JBL EVEREST speaker, which was playing in Mark Levinson, was producing a stable good sound.
posted by toons at 16:24 | Audio


SANSUI AU-ƒ¿907 Limited


SANSUI AU-ƒ¿907Limited

Released in 1994, the third-generation limited products of Sansui 907 integrated amplifier.

Equipped with a HYPER ƒ¿-X balance circuit, it featured a clean sound in the mid-high range of Toshiba's old MOS-FET (2SK405 / 2SJ115). This is still popular as the best sounding device for audio power MOSFETs along with Hitachi 2SJ49 / 2SK134.

Last night, after a long time, I tried to play an analog record to adjust my 2way speaker, but the amplifier was out of order and no sound was produced (CD direct input was sounded).

This morning, I opened the top plate to clean the inside, and after removing dust for the first time in several years, it started to sound normal.

# Inside of amplifier

# 6mm thick aluminum bonnet with copper powder coating

# Left channel power block

# Right channel power block, preamplifier section (black box at right end)

# Power block (large power transformer with a total weight of 13kg)

It was a total weight of 34kg, so I was concerned that it would hurt my waist when placed on the floor, but there was enough reward to clean it!
posted by toons at 03:15 | Audio


MarkAudio OM-MF519 vs OM-MF5, Fostex speaker frequency characteristic comparison - extra edition

Extra edition report of my handcrafted speakers characteristic comparison.

I tried to measure the frequency characteristics of MarkAudio OM-MF519, last year's model OM-MF5, and some FOSTEX products under the same conditions as much as possible.

The amplifier volume position was the same, pink noise, and the measurement position was fixed at 1m on the axis, but the height of the unit was adjusted precisely, and there were a difference of several centimeters.

This was measured frequency characteristics with RTA app "Audio Frequency Analyzer".

œOM-MF519 double bass reflex vs OM-MF5 bass reflex

# MarkAudio OM-MF519iDuct 15cm + 2.5cmj


# MarkAudio OM-MF5 (Tw is removed.)


As expected, the rich bass of OM-MF519 double bass reflex!
It seemed that the level around 30-50Hz is higher than OM-MF5 bass reflex.
For hearing, the left handed sound of the piano was resonated deeply. The loudness of the contrabass was also rich. And the mid-high range resolution is quite high, and the sound image localization was good due to the narrow baffle.

On the other hand, OM-MF5 bass reflex feeled like being pushed by energy. Since 60-100Hz was the same level as the mid range, the force of the base went up here. Full orchestra was a little difficult, but it was more suitable for Pops and Jazz.

The OM-MF519 double bass reflex was a 12mm front MDF, so I intended to reinforce it, but I found that the top plate was vibrating a little.

Since OM-MF5 bass reflex had 18mm side plate and bottom plate, it may be affected by the difference in rigidity.

Compared to the playback sound of two speakers, I prefered the normal bass reflection.

And measured other speakers under the same conditions!

œFostex FE83n


Fostex FE83n mini bass reflex, installed in the enclosure in the Ontomo MOOK appendix.
The sound pressure level was the same, and the low frequency response was attenuated gently from 100Hz, making it easy to hear.

œFostex M800


2016's Fostex M800.
This box was a simple square shape, but the inside is actually elaborate. It had a hard reinforcement and air venting duct port, but was almost a sealed design.

The low frequency response feeled better than FE83, but was less conservative than OM-MF5. Since the sound had a peak in the high range of the unit, there were a feeling that it will be a little audible, such as a scratching sound. The low range was neutral and sound power can be put in as it fully.

Each units and boxes had very different characteristics and sounds. How far I can get to my favorite sound is a long way off.
posted by toons at 02:12 | Audio


MarkAudio "OM-MF519" Speaker assembly Part 7 - frequency characteristics


After painting, I played a lot of music with this speaker for sound aging.

My personal impression is that the bass sound is very loud despite the 8cm full range. This is probably due to the bass enhancement effect of the double bass reflex.

# frequency characteristics (distance 1m, Pink noise, measurement by RTA app "Audio Frequency Analyzer"j

However, looking at the frequency characteristics measurement above, it seems that the elasticity and tightness are retreating compared to a general bass reflex type, probably because 125-200Hz is slightly depressed. In a sense, 100Hz or less is too high.

Next, I adjusted the length of the second duct and examined how the frequency characteristics changed.

# Original duct (15cm)


I prepared a paper pipe with a slightly smaller diameter and measured it in units of 2cm.

The level of 100Hz decreased in the duct +2cm. It may be the effect that the duct area is slightly reduced.

# Duct +2cm


After that, the length of the duct was increased by 2cm, but no significant change was observed. It is also possible to pick up ambient noise.

# Duct +4cm


# Duct +6cm


# Duct +8cm


# Duct +10cm


# Duct +12cm


As a trial, I changed the length of the upper and lower ducts extremely. But, it did not be much different from closing the duct.

# Duct +2cm, +10cm


These results was not clear, so I have to try several times with different dates. I try listening with a duct length of + 4cm for a while.
posted by toons at 03:20 | Audio


MarkAudio "OM-MF519" Speaker assembly Part 6 - external painting


As usual, the back and top plates were painted with black spray. To change the taste a little, I started to paint blue to the side plates, but the gas ran out during spraying on both sides.


I gave up and overlaid with black from above. After all, it doesn't look good in the surrounding black.

And then I found the remains of the cork sheet!


If the front baffle is cork-lined, I expect a retro feel. The baffle surface is where the woodworking bond is diluted and bonded, and the surface is coated with a thin aqueous varnish to increase strength.
The baffle edge was not able to be processed well and it floated a little around the middle.

It was made by cutting out round to fit the unit.
The sound absorbing material was inserted with the weight of the left and right channels matched.



Finally, the speaker was completed by tightening the duct screws!

posted by toons at 00:17 | Audio


MarkAudio "OM-MF519" Speaker assembly Part 5

MarkAudio OM-MF519 Double bass reflex speaker is almost completed.


However, the entire box is still under consideration for external painting.


For trial, I painted only the duct part of back side.

posted by toons at 01:50 | Audio


MarkAudio "OM-MF519" Speaker frequency characteristics, part 3

MarkAudio OM-MF519 Double bass reflex speaker is being adjusted.

The characteristic (1) was the result of adjusting the sound absorbing material to match my listening preference.

This was a measurement result at 1m above the unit axis (tilt about 15 degrees to the front of the baffle). The peak at 250Hz dropped, and the characteristics seemed to shift to 200Hz or below.

The characteristics of the second duct seemed to be concentrated around 60-100Hz. Then this area may not change unless the duct length is changed.

(1) Frequency characteristic of adjusting the sound absorbing material

Incidentally, the characteristic (2) was measured on the front axis of the unit. The peak of 12k-16kHz which is the high frequency characteristic of this unit was appeared.

(2) Frequency characteristic on the front axis of the unit

The characteristic (3) was the result of distance from the baffle to 2m.
Although a peak was seen at 100Hz, I thought that it was possible to get around 50Hz as a low frequency characteristic.

(3) Frequency characteristic from the baffle to 2m

As for my impression, I could hear the profound feeling of the bass and strings with the feeling of adding a subwoofer.

However, the feeling of tightness in the low frequency area will be reduced, so the rhythm may be lighter in jazz and pop music. I don't know if this is a characteristic of the box, or if the work accuracy or adjustment is insufficient.

Since the internal adjustment is over, I will consider finishing the box surface.
posted by toons at 02:54 | Audio


MarkAudio "OM-MF519" Speaker frequency characteristics, part 2


I tried putting the sound absorbing material into the first and second cabinets. It was shifted to the low side, 40/50Hz level up, dipped occurs at 160Hz.

And I reduced them for the first cabinet a little more. Adjustment was troublesome. Although it got more sense of volume in my hearing, the sound response was declining.

I will try to make a sound with this for a while.
posted by toons at 09:29 | Audio


MarkAudio "OM-MF519" Speaker frequency characteristics, part 1

Attached the MarkAudio "OM-MF519" unit to the double bass reflex speaker box, so I made sound test.

I measured the frequency characteristics at the begining of playback and after aging for 1 hour. It was tested by the RTA app "Audio Frequency Analyzer" with pink noise.

# Begining of playback

At the start of playback, there was a dip at 125Hz, but the level increased a little in about an hour.

# After aging for 1 hour

The original high frequency peak of 12-16kHz has disappeared. This is probably because the baffle is slanted and the measurement point is about 15 degrees off the unit front axis.

In addition, when blocking to tape one duct as a test, the 63/80Hz sound level was dropped. The second cabinet duct was seemed to have worked well.

# Blocking one duct

It wasn't the final sound because there was no sound absorbing material yet in the box, but the sound resolution was very good. The bass range did not drop to the lowest sound, but it had enough low-pitched feeling unlike a simple bass reflex.
posted by toons at 00:12 | Audio


MarkAudio "OM-MF519" Speaker assembly Part 4


I scraped off the gap between the baffle and the side plate. I found that it had a little off, but I'll try sanding again even before final painting.

The duct plate was temporarily fixed. I'll measure the frequency characteristics with no sound absorbing material by attaching the speaker unit once.
posted by toons at 01:15 | Audio