Yasushi Matsumoto on the Alpair 5 - digital future

[markaudio]

Hi Guys,

There's some very interesting and innovative work that features the Alpair 5 by Yasushi Matsumoto San in Japan.

Briefly, I understand Yasushi was a development engineer for Honda's Formula One race car team. He's a techno-wizard and very switched on to many developments in audio control technology.

There's lots of useful information on digital equalisation, graphs and data that may be useful for full range users that might work in a variety of applications.

Yasushi's English is excellent, he's kindly produced his work in dual language. Here's the link to the English site:

http://lean-audio.blogspot.com/2009/04/report-of-alpair5-aplication.html

Cheers,

Mark.

 

[ttan98]

could not find the Xmax spec. on his website for both drivers.

question,

1. Does the drive, Alpair 5 has suffcient Xmax to handle 30dB boost?

 

[Matsumoto]

could not find the Xmax spec. on his website for both drivers.

question,

1. Does the drive, Alpair 5 has suffcient Xmax to handle 30dB boost?

It depends on mainly two factors;
1. Sound volume
If you are listening music with small sound volume then you will have a plenty of margin against Xmax. I�fm listening at approx. 80cm distance from the speakers ( maybe 2 W amp. power should be enough, even though my wife sometimes complains). This extreme boosting is possible because of near-field listening style. If you approach to the speaker, then you can get the same sound pressure level at your ears with less sound volume from the speakers. If you are listening in a big room with nearly full volume then the boost possibility must be quite limited.

2. Original signal level at the boosting frequency
In most of music sources, original signal levels below 50Hz are not so strong even in classical symphonies (I tried Beethoven No.1 ... No.9). Therefore +30dB at 25Hz is generally not so critical.
However, as I mentioned in my Blog, some special music like as modern orchestra with extraordinary strong bass drums bring the drivers to Xmax because of strong signal level. In such case the boost factor must be reduced.

I also couldn�ft believe it really possible before trying actually.

Matsumoto

 

[Antripodean]

Matsumoto, great result! Congratulations on your work. I think having really good sound near field with a computer is definitely something that I would like to have.
I like the software. Interested to know if there is/will be an English version.
domo origato (limit of my Japanese

 

[EUVL]

I wonder what the transient (impulse) response would look like with so much bass boost ??

Patrick


PS @MarkF

Did you receive the email from MarkL about a week ago?
Could you kindly have a quick look?
Thx, Patrick

 

[Matsumoto]

I like the software. Interested to know if there is/will be an English version.
domo origato (limit of my Japanese

Antripodean san,
Unfortunately the software Frieve Audio is available only with Japanese version. You can download it from;
http://www.vector.co.jp/soft/dl/win95/art/se387572.html : Free version, no automatic compensation, any other functionalities are exactly same as the shareware version.

http://www.vector.co.jp/soft/dl/win95/art/se389422.html : Shareware version (M-Class), 3,465YEN, automatic compensation possible

If your sound card is not ASIO compatible, then you need ASIO4ALL driver additionally to perform automatic compensation.
http://www.asio4all.com/ : ASIO4ALL download site

Are there any similar software in the world?

 

[Matsumoto]

I wonder what the transient (impulse) response would look like with so much bass boost ??

EUVL san,

I was also anxious about the issue.
However, at this moment I can only say, boosted Alpair5 sounds better (faster or tighter or clearer) than my own cheap powered subwoofer(13cm 30W). The software also compensate phase delay that increases in lower frequency range (this is inevitable in any laud speakers). It might be working some how? but I�fm not sure.

+30dB looks quite shocking, however signal level below 50Hz is quite low in most of music sources especially non-electrical tunes. (see attached picture) Furthermore +30dB is just a peak value at 25Hz. Therefore actual effect is not so big in many cases except for some extraordinary tunes like as Rit of Spring / Stravinsky. Usually I boost down to approx. 40 Hz flat and limit the max. factor (approx. +18dB) down to 25Hz, then sharply cut-off (See figure in my Blog, "reduced boosting cactor"). It�fs enough and safer.

 

[markaudio]

Hi Patrick,
Just caught up with your PS.
I emailed Mark L some time back about helping you test your design. I'm happy to put your design in the anechoic chamber but may not have the time until June.

Thanks

Mark.

 

[Matsumoto]

I have just finalized this trial as below;

You can also see the total article on my Blog.
http://lean-audio.blogspot.com/

-------------------------------------------------------------------
3. Conclusions
Now, I�fm going to finish this audio trial on my desktop. It is quite comfortable to listen the real full range sound (30Hz to 30kHz) generated from just a single cone with quite small diameter (approx. 5cm) in a simple sealed box without any reverse ports. This was a kind of dream.

If you can accept this kind of new technologies (i.e. computer audio system with digital equalizing), limited sound volume (near-field listening style) and trivial sacrifices in the sound qualities (i.e. deterioration in S/N due to expanded dynamic range and distortions due to larger diaphragm excursion, honestly I don't feel any problems) , then you can realize the dream quite easily.

I selected Alpair5 originally because of the subwoofer integration. If you would not be so adhering to the super detail of Alpair5 in mid-high range, I would recommend Alpair6(fs=74Hz) or CHR-70(fs=70Hz) for this kind of desktop applications (i.e. digital boost without subwoofer) to reduce the boosting factors . I expect 6dB reduction with those drivers in my calculation.

If your listening distance exceeds 1 m, then Alpair10 full range or Alpair10 woofer + Alpair5 could be suitable. In this case, I expect 10dB or more reduction in the boosting factors.
--------------------------------------------------------------
Matsumoto

 

[ultrakaz]

Thanks for sharing. Great information. Hopefully, there will be an english windows version available.

Within the scope of use you defined; < one meter distance, low listening levels, this is a viable alternative. Just equalizing an existing computer speaker should be an improvement, if not at the level of the Alpair 5.

For most of though, I think the hobby of diy fullrange involves the challenge (enjoyment) of researching, designing and constructing a box to maximize a driver's potential; through experimentation a desired result is achieved and safisfaction is part of the reward. To the old school/purist, crossovers are usually frowned upon and equalization of the signal is not considered, especially for those of us that still listen to analog.

 

[Matsumoto]

The software is only available in Japanese language.

However you can do exactly the same process (automatic compensation + manual equalizing) if you integrate an external digital equalizer to your existing audio system;
http://www.behringer.com/EN/Products/DEQ2496.aspx (English site)
No computers necessary, Digital In/Out as well as Analog In/Out possible
approx. 40,000.- YEN in Japan

Although this device is originally designed for music creators, many Japanese audio freaks are enjoying it quite comfortably.
http://audiolike.exblog.jp/ (Japanese site)

You need a microphone (option) to perform the automatic compensation.

 

[Bigun]

This is very impressive work, the idea of boosting to get the low end was something I was thinking about with a 2-way design and had not thought of the full range driver being at all suitable. You have shown that this is not only possible, but works very well.

 

[Matsumoto]

Honestly, I cannot be really sure whether I'm doing the right thing (I�fm sure many of you have the same feelings).

To be more confident, I did simple measurements as below;

Testing method
1) Generates WAV files containing several sinusoidal signals (30/40/50/70/100Hz, with 0/-6 dB)
2) Playbacks the test files with my usual amplifier volume position (approx. 1/5 angular position, full power=60W(spec.data)).
3) Records the sounds via a microphone just in front of a speaker.
4) Compares the recoded signals with the original signals.
.
.
see the results in my Blog.
http://lean-audio.blogspot.com/
.
.
In other words, �gmaximum low boosting�h means �greduction of mid-high range from the maximum powered condition of the driver". Therefore basically I would recommend to use Alpair6 or CHR-70 for this kind of extreme boosting applications, with which you could have much more boosting potential (see below table).

driver / X-max(1way) / max. Power
Alpair5 / 2.5mm / 12W
Aplair6 / 5.0mm / 30W
CHR-70 / 4.5mm / 40W

(data from Mark Audio home page)

 

[EUVL]

IMHO you would not need any bass boosting with the Alüpair 6 in a Bass Reflex box.

http://www.diyaudio.com/forums/showthread.php?s=&threadid=144211

And it will never be able to replace a subwoofer if you want it down to 20Hz or so. But then not every subwoofer would do 20Hz anyway.


Patrick

 

[HareBrained]

And IMO, the CHR70 may not be the best candidate. When pushed, the CHR70 goes wonkers pretty quick. And in the dual-chamber reflex box, F3~45Hz. Pretty impressive as is. I played around with the Creative EQ in my PC and I was not impressed with the results, even at low levels and low boost. Now there are many unquantifiable factors and it was less then scientific but sonic output got muddy very quick. To make it happen, it will definitely take better source equipment than I'm using.