Beyma 8BX

[sumacSK]

Hi,

I know it is not completly single driver, but still single point source... 😉 I'm considering buing this driver and use it on open baffle (or maybe closed) with subwoofer. I'm wondering if there is someone who has some experiences with this driver. Any crossover suggestions? (I have some crossover scheme from german magazine, but it is for beyma 8DX... ) I know that the best way would be active crossover (like behringer DCX) but I'm affrraid that my budget don't allouds me buying it... My room is about 25 m2, musical tastes: everything.
Sorry for my bad english 😕

Thanks Martin

 

[knorke]

I used years ago the predecessor of the 8bx (which had a paper cone) in a closed box (around 20l) with good results. It had strong bass output so you might not need necessarily a subwoofer in your room.

 

[Jimmy154]

Haha, I knew the day would come when I would see a Slovak on here 😀

 

[soongsc]

Haha, I knew the day would come when I would see a Slovak on here 😀

Prague is not in Solvakia. I'm confused.
😕

 

[DarkOne]

Haha, I knew the day would come when I would see a Slovak on here 😀

He is not alone here. Here are few Slovaks on forums for a long time.

 

[sumacSK]

Hi,

Yes there are more slovaks here... But back to speakers... So nobody with experiences with 8BX???????

Martin

 

[Jimmy154]

Prague is not in Slovakia. I'm confused.
😕

He has Slovakian flag. Lot of Slovaks go to Prague to work and/or study, like my parents when they were young studied there. They want me to go study there too, but I'm too smart already 😀

I know nothing about speakers, sorry

 

[belin]

I have a pair of those that i intend to use like surround channels in HT. I haven't measured it yet, maybe this weekend. they are in a proto baffle with a size appropriate for my wife, so is not big in excess.

Sorry for my pathetic english.

 

[sumacSK]

Hi belin,

Thanks for the response! So you are using that speakers on open baffle? What size? What kind of crossover do you use? And most important: how do they sound?

Thans a lot Martin

 

[belin]

Hi SamacSK,
I'm sorry, but i couldn't do the acoustic measures of the drivers. The power supply of my computer chose to broke this saturday, carrying with him the motherboard. Maybe you can use the T-S parameters that I measured time before. Here they are:
fs 47 Hz
Qes 0.590
Qms 6.8
Qts 0.543
Vas 36l
Re 5.5 Ohm
Le 0.05
Sd 216 cm2
(from the manufacturer)
Xmax 5mm
Pe 100w

The crossover will come next to the acoustic measurements, for now I use foobar for equalization porpouses. I have to say that I'm not really good optimizing the system by ear, and the sound I obtained is not great at all. I'll try to put photos later on the week.

Sorry again, maybe in a few days...

 

[sumacSK]

Hi belin,

Thanks for information. I'm looking forward to see measurements and crossover scheme. BTW I have some crossover scheme from german magazine, so if you want I can send you...

Martin

 

[soongsc]

Hi belin,

Thanks for information. I'm looking forward to see measurements and crossover scheme. BTW I have some crossover scheme from german magazine, so if you want I can send you...

Martin

Pardon me,

but how do you plan to us crossovers on a full range speaker?

 

[Variac]

From the first post, I suspect it is a coaxial speaker, with a separate tweeter.

 

[soongsc]

From the first post, I suspect it is a coaxial speaker, with a separate tweeter.

You're right. I don't think these could be use open baffle. Looks like an interesting project.

 

[belin]

Hi,
I'll be very pleased if you send me the scheme SumacSK, thanks . By the way, the power supply wil come in two days. I'll try to do the measurements as soon as possible.

I have to say that i don't pretend to go low nor loud with these, maybe just to 80 hz with a litle active help. The porpouse of the drivers in my case is for rear channel in ht. I modeled it with winISD Pro for closed and vented boxes, with Martin King's tools for TL and MLTL, and with Thorsten Loesch spreadsheet for dipole, but the real concern is that my wife don't want to see boxes near the sofa. If this wasn't the case, the closed box don't have a size that big if you can live with a no flat response, or a big MLTL for low end extension... (Be careful with my comments, i'm not and expert, nor i pretend to be, this is my second project, and my skills are not that great).

Soongsc, in http://profesional.beyma.com , inside the section dedicated for coaxial units, it's possible to get information about the driver. I think they are a little bit optimists (7Khz for the midbass unit i think is a little high), but you can get a reference.

 

[soongsc]

It would be nice to see some impedance plots and the FR phase plots. At first glance, it seems a XO around 4K~5K would be a good start. If you're not concerned about effeciency, series XO probably would be good for this application.

 

[sumacSK]

Hi,

Yes it is coaxial speaker, here you can find more information: http://profesional.beyma.com/ENGLISH/pdf/descarga.php?pdf=8BX.pdf . Belin, give me please your e-mail adress where I can send you scheme.

Martin

 

[Variac]

It couldn't hurt to contact Beyma and ask if they have a recommended crossover for that Coax

 

[belin]

Some photos

Hi,
I take some photos of the beymas in the proto baffle yesterday.
Here is the front of the baffle. (32 cm wide, 55 cm high, 10 cm each wing). The driver is about 72 cm above the floor, which give a null about 700 hz in Thorsten's dipole spreadsheet, and the size make a high pass of 6db/oct with a -3db point near the 210 hz, with a +3 db plateau from 250 hz up to 1200 hz.

I don't have the power supply yet, so i can't measure the response nor i can correlate the calculations with the reality, sorry...

 

[belin]

The rear.