Beyma 8AG/N horn or "the Viech"

[Cyburgs]

... some new measurements this weekend, an the result was very interesting.
I noticed that the treble reproduction of my "Viecher" improved over the last weeks and wanted to see, if this could also be confirmed by measurement.

This is the measurement I did when the "Viecher" were new. It was made at the begin of January, 2 months ago.



This measurement I did yesterday:



Noc changes on the Viech have been done, and also the measurement parameters were the same. All changes in the frequency plot are due to break-in of the drivers. This improvement in the high frequency area is also acoustically noticeable.
This shows that the break-in of fullrange drivers seems to be more than a myth.

Nice greetings, Berndt

[panos29]

Dear Berndt,

Excellent results! Very nice and well thought and documented project, my congratulations. What I would like to ask concerning the measurements, what kind of equipment and setup did you used for taking these measurements? Meaning height and distanse of microphone, room location when measuring and also what equipment and software. I am in the search of measuring my horn speakers and am not yet sure how to accomplish this task.

My best regards

[Cyburgs]

Hi Panos,

I use a measurement system called DLSA, which comes from Germany. The fine thing is that it comes with micro (calibration file included), feature box and Software. All you need is to plug the box via parallel port in the computer and install the software. No hassle with soundcards, microphone calibration and other issues. Also the no-nonsense user-interface is nice to work with. The only disadvantage is the lack of harmonic distortion measurement ability.

http://www.dlsa.de/

The setup up the measurement was the following:
- Distance micro-driver was 1 meter.
- The speaker was taken away from the wall.
- The micro was aimed 0°/0° directly at the dustcap.
- Input was 1 Watt.
- Reference signal was taken after the Amp to exclude influence of the Amp.

I'm happy that you like the Viech construction, nice greetings to Greece (my favourite holiday destination BTW, do you know Finikounda/Messinia?), Berndt

[panos29]

Dear Berndt,

I really like finikounda! I've been there and in Coroni twice! Hehehe small world ! Anyway the site of the measuring system is not very informative isnt it? How much does it cost anyway? I just recently finished my horn http://audio.dynatech.gr/horny.htm which i designed from scratch and really enjoy but I would like to give it a try and measure it so I can play with stuffing to see if I can get any improvement.

Regards,

Panos

[lohk]

Berndt,

where did you buy the Beymas in Austria? I want to try your design as soon as possible.

best wishes
Klaus

[lohk]

BTW,

I would translate "Viech" (I like that name!) with "beast".
For all of you not familiar with Austrian german "Viech" would be pronounced in a sort of gaelic like "feech"...

[Cyburgs]

Yeah, beast, yeah ...

Hi Klaus,
I bought the drivers at the official Austrian Beyma distribution, but I am very sorry that I can not give you more data, because I lost the address. I looked after the sheet of paper where I noted it, but it is gone, sorry for that. I originally visited Musik-Produktiv http://www.musik-produktiv.at because they also distribute Beyma chassis and they gave me the address. Maybe give them a call and they will tell you, too.

@Panos: Very impressive horns! And also nice woodwork. Seems like they could blow you out of the windows, if you are not cautious

Nice greetings, Berndt

[Elias]

Se on moro!

I took the effort of putting the images on top each others for better readability, and what do you see actually? Not only the 10kHz region but the whole freq response contains variations of several dBs.

Important would be to know if these changes are really due to driver 'burn in' during the time, or has the measurement conditions changed. The variations could come from slightly different room locations of the speaker and the microphone, or simple numerical noise of the FFT of the measurement software.

So how is it?

I'm interested because in one of these days a mailman should bring me a pair of 8AG/N too

- Elias

[qwad]

ELIAS, I would say it is ' burn -in' [ the result of the surround and spider softening up> with continued use ] as you say in your post at least the nasty peak at 7 k has smoothed off somewhat as has the rest of the response overall much nicer than original cheers TC

[Klimon]

Hello,

I'm building a pair of these 'Beesten' - Flemish - (when I'm done posting this reply, I'm of to the 'glue-room' again ). The design and plans seem very nice (Well, I'm building them, so...), although I have found a minor error: the length of the E-panel with 25°/-25° cut is ca. one cm too short (it isn't flush with the front panel/ side panel edges).

For the construction I'm using MDF (which should be better than fibreboard), and it won't hurt to round the ends of panels B and C with a sander either, which makes the horn smoother. Maybe I'll also add a very small triangular piece of wood in the corner between C and D to smooth it out a little further. I'll also fill the voids left by the diagonal panels (E, H, I, J) with sand to kill the cabinet vibrations - when you do this, be sure to dry the sand (which is by definition quite moist) by 'baking' it in the oven.

I've had the Beyma drivers for a little while now, and playing them without a cabinet, at first they sounded terrible (very harsh highs). By now this has bettered substantially, and I believe a long burn-in period will indeed be characteristic for high-efficiency fullranges.

Thank for the great plans Berndt, and I'll keep you guys posted on the results!