New website coming soon

Finally,I gave up to do the website myself. Too much to do and not enough time. After I saw what can be done with our FinkTeam site,  I have to say,  other people are better and so I stick to my speakers.

 

Website back online

after our website got badly hacked, we had to take it off and clean it. I found 15 infected files….and I thought only important websites get hacked.

On one domain, we had 8000 (!) html files with all sort of crap on!

Now all software is up to date and a protection system got installed as well….time to add some new content and start to work on a fresh website.

KLIPPEL Laser Scanner

In addition to our POLYTEC Laser Scanner,we got the Klippel Laser Scanner recently. Why? Well,the Klippel device uses a Triangulation Laser and can output dimensions. It also couples the measurements to the surrounding air and allows to predict SPL including directivity –with a simple click only.

Here is what you get as animated picture:

Moving cone at 4347Hz

You can also have a look at the profile and here it’s easy to spot the cone/surround junction to be the area to work on:

Cone profile at 4347Hz

 

A really nice feature is the option to separate the part of the cone that vibrates in phase and the part that is not in phase and of course the result of both. This option really helps to understand a response curve of a speaker:

 

 

 

 

 

 

 

 

 

 

 

Last,but no least it is possible to show radial modes and circular  modes in different animations. Below is the circular mode of the driver. As you can see,there is a little bit of a Rocking Mode visible:

 

 

All together,a nice new toy. Guess it will take a few days before we know how to use it best. The system will definitely help to identify unknown drivers by giving us the real dimensions. Well done,Mr. Klippel

 

 

 

 

 

 

 

 

OK,late again with updates:-(

Last time I promised to write more –unfortunately it did not work out. Too much work and not enough time.

A lot happened –new people,new equipment and new customers.

I’ll report about the new people soon and add them to the list and I’ll also report about the new Klippel Scanning Laser we got recently. Now we have two Scanner systems:The Polytec and the Klippel.
The Polytec is much faster,but does not allow to get dimensions out of the Scan. The Klippel system exports dimensions –a useful feature to get cone shapes and surround shapes out of a drive unit without taking it apart. The Klippel also gives us some nice loudspeaker specific results. It still does not tell you what to do next,but at least you have a chance to get information what moving part does what. It shows directivity just from the scan,tells you what parts adds to the output and what parts does not and yes,it shows you the response curve you can expect. Very impressive.

Effect of Thermal Compression in real world subwoofers

Whenever we at FAC design a subwoofer,we test after finishing the equalizing what the loudspeaker does at higher levels. The best method is to do a compression measurement. During this measurement,the input level of the subwoofer is increased and we check if the output level changes follows

A subwoofer after filtering

If you normalize the results to the starting value,you can get a nice picture of what the sub does in real life.

Compression test with the subwoofer shown above

There are two obvious sources of compression. First of all –in case of a ported design- the port starts to fail at higher levels due to too high air velocity,with the result that the region around the tuning frequency does not go loud enough.
The second effect is the thermal compression. The coil get’s hot,therefore the resistance rises and the result is a lower level.

But if you carefully compare the response curve of the compression measurements,you see that there is a difference. Even so the “static”measured curve looks flat,ALL compression curves –even the low level ones –show some slightly falling character.

So what happened? Well,in case of this particular measurement,the driver is measured at each individual frequency with all the defined level steps. During that period from small voltage to larger voltage,the temperature rises in the voice coil. When jumping to the next frequency,even at the lowest level,the coil is still hot and so the level is slightly reduced. So far,so good,but due to the impedance curve of the subwoofer,this change in level is not constant over frequency. At the impedance peak around 60Hz,the level difference is much smaller. As a result,this level stays more or less even at higher levels,but above and below,the levels goes down,depending on the temperature of the voice coil.

Impedance of Subwoofer without amplifgier

One the measurement below the following test was done:The green curve shows the standard measurement with a relatively low input level of 0.1V. The red one was done  again with 0.1V just after finishing a high level faster sweep  with 1.5V. The blue curve shows the same,but this time the high level sweep was done slower to give the coil time to heat up.

One could say this is a fault in the measurement and maybe it needs to be changed to avoid that effect,but if demonstrates nicely what happens in the real world with music or a movie. The coil get’s hot during peaks or heavy bottom end and the resulting response curve is changing. For the design process it means to make sure that from the frequency of the high impedance peak,the “static”response rises slightly around 1dB. That means in real live you get a better balanced behavior.

Compression curves after filter modification

This modification might not make a good subwoofer starting with a bad one,but a carefully look at thermal compression cannot be wrong and it is not a lot more work to take care about the effects.

Thanks to Christian Gather,who made all the measurements and had the initial idea.

HighResDownload

Carsten Hicking of DigitalHighend published a page with links of websites for High-Resolution Audio downloads. Please support him if you find more and let him know,so the page can be updated. HighResDownload

On the left the company dog of DigitalHighend 🙂

See you in Munich

bmrHi,

if you would like to meet us,you have a chance during the High-End show in Munich. The show starts on the 21st and ends on the 24th.

Here are some details:HighendSociety

You will find us at the Thorens booth,showing the new Thorens turntable.

So,see you in Munich!

Hallo HiFi World

Welcome to our new webpage that we created to give you some information of what we do in our company. Enjoy –but be careful,it’s always somewhat BETA

Best regards

Karl-Heinz Fink