Backloaded Horn Speaker

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Number of visitors to this page is since Jun. 1 2002.
Last update of this page was Jun. 1 2002.


This is continued from an article of "Yakinori" amplifier, at first, I want to make a vacuum tube amplifier. But I have no speaker to connect the amplifier now, different from 30 years ago when I did electronic DIY and audio hobby. It is no good to connect a conventional cheap speaker for connecting to the amplifier which is not sold in common. (And I cannot buy expensive speaker and have no space to set it.) So, I want to make speakers too. Because the amplifier is not so common STC, the speaker will be also not so common..... I find a Backloaded Horn Speaker. In old days, I knew Mr. Nagaoka Tetsuo's articles in FM magazines. But I never think to make speakers. (But I made an FM tuner.... in an old story, the day of opening operation of FM Tokyo, not J-WAVE. At 2:05 pm, "Stereo Kayou variety" program is broadcasted on everyday. There are many maniac stories.....) This backload horn speaker also looks like become popular in '1990s like STC amplifier. I know for the first time. Because I know this story, it is automatically decided to make backload horn for a strange brain person like me.
Next, I bought Mr. Nagaoka's books. Many strange speakers are introduced like "Swan". Every one looks like hard. But I have no experience to make a hand made speaker yet. I do not make wooden equipment and have no tool to make. I do not think to make speakers easily. Further, in the article in the books, the size of the speaker is too large to set in my room. There is no money and no space to set....mmmm... And when I went to home center store near my house, I found that there is no wood for suitable to make speakers. There are many kind of woods for making tables or racks e.g. pine woods. Anyway, it seems that the road to go is closed for me. I check more in the condition that; backloaded horn, small, not expensive, and not to be cut wood by myself...... There is MAKIZOU (Japanese), it's nice. They supply smaller one than the smallest backloaded horn which is wrote in Mr. Nagaoka's books. This is small and not expensive. I decide to order to MAKIZOU 8cm backloaded horn speaker M-8BH. Working of MAKIZOU is very good. I make speaker with only an adhesive with no nail in this time. I do an little error for making but the size of the woods cut by MAKIZOU is completely adjusted with no error.
SPEAKER'S CUT MAKIZOU---MAKIZOU's site. (Japanese) In my home, we call "Yakinori" for the vacuum tube amplifier and "MAKIZOU" for the backloaded horn speaker.


all materials This is all materials sent from MAKIZOU. This is compact size, it's nice.
start to make I use no nails. It is enough for small one like this. Making process is easy with a manual written by MAKIZOU. The interval time is needed for drying up the adhesive. "The next is the next week..." so many weeks are needed to make.
almost completed Almost completed. This is like a maze. I can imagine the road goes the sound. All parts inside is set on the one side of the side wall.
stones and damping mat Before completing last side wall. This situation is the best to see the structure inside. I take a photo because I will never seen this inside. Put the damping mat to the space under the unit. The needed quantity of the mat is very few. The stone which is set at the bottom is the stone for the goldfish. Packing stones in a plastic bag, and cover it by felt. Do not forget the lines to the unit. If you have not connected, it cannot be done after the last side wall is set.
water-varnish is painted Vanish in water-paint is used. Water-paint is nice for not smelling, it is suitable for indoor painting. I use sandpaper before painting, but there is no good painted place because of a bad technique of assembling and some remainder of adhesive. Further, I paint by a cheap brush and have not enough technique to paint, there is irregular surface.
Completed by setting unit After vanish is dried, I set units. Unit is FOSTEX FE-87E. This is magnetic free type, but the era of CRT, tapes and floppy disks is just ending. I bought it too in AKIBA at a shopping of the parts for "Yakinori" amplifier. I also bought the net. Model No. is Speaker Grill K308 (2 pcs.). I think that the net is indispensable for the family with little children or cats.
Setting with Yakinori amplifier I set speaker with Yakinori amplifier to a listening position. The place is on the simple table. I do mosaic the photo a part of private, anyway, there is no space to set speakers on the floor. I clear on the table and put amplifier and speakers on it by force. Fortunately, I feel this speaker is not too big even on the table because the size of M-8BH is small. The height of the unit is just the same height of my ear, it's very nice. Now let's listen the music. The source is CASIO portable CD player PZ-860. The size of it is good to put on there, and performance is suitable for this purpose. By a half transparent cover of the CD player, I can see the disc spin. It's nice like as an LP record in old days.


Because I listen the sound after completed both construction of Yakinori and Makizou, the impression is for added sound both of them. First, about backloaded horn speaker, like many people said, there is not enough high frequency sound at the first time. I feel no lack of low frequency sound, maybe the effect of the backloaded horn mechanism even only 8 cm unit. There is no impression like common cheap artificial low frequency sound made by tone control circuit. The sound is natural. Location of the sound is nice. Because there is only one full range unit, the condition for the location of the sound is the best. I do not listen enough as an aging yet, I feel the impression that the high frequency sound is alive than one week ago. Maybe relation exist by the handmade speaker, it looks like live things.
About vacuum tube amplifier, after changing FET to transistor, the distortion in low power sound is not occurred. This amplifier is not suitable for the purpose to listen big power sound. Because 6BM8 has not enough power, and STC circuit is not designed for getting full power. I feel not enough power for enjoying hard rock with full volume, or fortissimo in full orchestra. (but this is better than usual TV or PC's speakers.) I like to listen small Jazz band or vocals by this amplifier. It is the best for enjoying '70s atmosphere to play Carpenters. Specially in female vocal, resolution and freshness of the sound is important I think. I am satisfied about it with the character of STC circuit maybe. There is no hum noise. There is only one noise of spinning of CD player if volume turn full, but this is nothing for the quality because I cannot turn volume full in usual. About looking, of course I can enjoy the heater of the tube in the night, and even in the day time, I can enjoy not flat painting of vanish ? (You can find blurs even in the photo...)

There are many things for everyday life like PC and magazine etc. in the house, there is the only space around "Yakinori" and "Makizou" for '1970s rising above the real world. Specially, I recommend this size for the small rooms having not enought floor space to put materials at all.

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