Im new to building speakers. I already read the "Handbuch der Lautsprechertechnik" and rn im on The "Loudspeaker Design Cookbook". I tried to get my info there but didnt find what i was looking for. So: I bought a driver B&C 8BG51. I want to use it in a closed Box (Frequencyband 100-500Hz) because i already built a Bassreflex Speaker for underneath.
Online the Frequency Graph on B&C site looks like this
Now I calculated a box size for Qtc beeing 0.707 of 8.484l. If i now enter all the Data into AJHorn
i get this Graph:
which looks pretty underwhelming.
Now i found out, that the main Reason the Graph looks like this is that i Dialed in Rdc/Re of 5.1Ohm. If i was to dial in 8Ohm it would look like this:
which would be much closer to what i would have expected.
Can you guys tell me if i did a mistake in the Simulation or is that a common behaviour of Drivers under certain circumstances.
Cheers and a nice Weekend
Elias
Online the Frequency Graph on B&C site looks like this
Now I calculated a box size for Qtc beeing 0.707 of 8.484l. If i now enter all the Data into AJHorn
i get this Graph:
which looks pretty underwhelming.
Now i found out, that the main Reason the Graph looks like this is that i Dialed in Rdc/Re of 5.1Ohm. If i was to dial in 8Ohm it would look like this:
which would be much closer to what i would have expected.
Can you guys tell me if i did a mistake in the Simulation or is that a common behaviour of Drivers under certain circumstances.
Cheers and a nice Weekend
Elias
The value is correct. I notice AJHorn is taking other factors into consideration which may be appropriate but which could be obscuring what you're trying to see. Have you confirmed this by using a different box modeller? While there you could model damping material since this is going to be your safety net once the box is built.
I will try to Simulate in Akabak today and check if i get similar results. When i put the driver in a 8.484l Enclousure in WinISD i get a "normal" result but as far as i see just the rolloff towards the lower Frequenciees is concerned in WinISD. So im not getting this weird hump and rolloff towards high frequencies.
Damping is the ßRK Value in AJHorn it reaches from 0 to 1000 and i tried different Values. What would you recommend to find our the right amount of damping?
Damping is the ßRK Value in AJHorn it reaches from 0 to 1000 and i tried different Values. What would you recommend to find our the right amount of damping?
You have to use the actual, measured R of the speaker. This is what you get with a multimeter in low Ohm position.
The graph of the speaker is measured in a very large box, typical around 3000 liter, which means free air.
When you put it into a smaller volume, the Fs rises, just like Qtb. The smaller the box, the higher the bump before the level drops off.
The nominal Ohm value of a speaker is just near the measured on. Like 6.6 Ohm DC will make an 8 Ohm speaker or 3.1 a 4 Ohm chassis. Never mix that up!
If you use a passive crossover, the DC resistance of a coil in series with the speaker counts and will change the frequency response.
The graph of the speaker is measured in a very large box, typical around 3000 liter, which means free air.
When you put it into a smaller volume, the Fs rises, just like Qtb. The smaller the box, the higher the bump before the level drops off.
The nominal Ohm value of a speaker is just near the measured on. Like 6.6 Ohm DC will make an 8 Ohm speaker or 3.1 a 4 Ohm chassis. Never mix that up!
If you use a passive crossover, the DC resistance of a coil in series with the speaker counts and will change the frequency response.
I just simulated your driver in a 8 liter closed enclosure. Got a nice response, straight and slowly dropping at 100Hz.
Just enter correct TSP and anything will be fine.
https://loudspeakerdatabase.com/BC/8BG51
Just enter correct TSP and anything will be fine.
https://loudspeakerdatabase.com/BC/8BG51
That's a lot of power for a simple task. When I want a closed box I just calculate it in my head. So I wonder if that's really all you're trying to do...
Hey Thank you very much for the loudspeakerdatabase! In AJ Horn they ask for Impedance at 1kHz and 10kHz. If i read it from the Datasheet provided by B&C it says 8.9Ohm at 1kHz and 14Ohm at 10kHz.
At the loudspeakerdatabase it is 5.8 and 31.8 Ohm.
I dont know why they alter that strong or if i made a mistake but now that im using the new provided Data the Driver looks decent in the enclosure.
PS: In the same Turn it makes me wonder why this is not classyfied as a 6Ohm Speaker since in his operating range it is pretty close to 6Ohm
Ok, i measured the Driver in REW and thats the Impedance Graph:
As you see, the Impedance Graph from loudspeakerdatabase seems wrong. And here i am again, wondering why the Frequenzyband looks so bad
I dont understand what you do. I can tell you that simulations in the programs that have been mentioned are spot on, if the TSP are right. B&C is no Chinese company and the TSP match reality. If you only want to prove anything and anyone wrong, first learn a little about this stuff. Otherwise, use the data, then buy a driver, measure it's TSP after preconditioning, then do your own simulation and build a cabinet. Calibrate your gear and measure the resulting response. You will find them to be as simulated. We have 2024, not 1980... some stuff has become pretty normal.
If you buy, for example, a Thomann "The Box" speaker, you should measure the individual driver batch you got, as these TSP's are decades old und worthless.
If you buy, for example, a Thomann "The Box" speaker, you should measure the individual driver batch you got, as these TSP's are decades old und worthless.
Maybe buy them and measure your self? What do you expect in difference? It doesn't matter if you put the driver in a closed 6 or 9 liter volume. You have to measure them anyway on your personal baffle to make a crossover. The response will have not much in common with the ones you see on a DIN Schallwand.
You got to read the right things out of books and weight their importance.
If you don't like to make your own decissions and take a minimal risk, you are not the one to develop speakers on your own. Those that do usually have a stock of drivers that did not work out in the end. Developing speakers is a life time learning curve, there is only a handfull of people out there that make a living from it. Too much learning, usually a university degree and years of practice. Today the "any idiot can do it, so me too" attitude has taken over. Everyone thinks he is an expert in anything, because of the internet. People that have some real knowledge of speaker building could tell you how complicated a 3-way speaker is in reality, but they are tired of hearing "yes, but...".
You got to read the right things out of books and weight their importance.
If you don't like to make your own decissions and take a minimal risk, you are not the one to develop speakers on your own. Those that do usually have a stock of drivers that did not work out in the end. Developing speakers is a life time learning curve, there is only a handfull of people out there that make a living from it. Too much learning, usually a university degree and years of practice. Today the "any idiot can do it, so me too" attitude has taken over. Everyone thinks he is an expert in anything, because of the internet. People that have some real knowledge of speaker building could tell you how complicated a 3-way speaker is in reality, but they are tired of hearing "yes, but...".
Thank you for your kind Words Big Dog Your right, im not an expert, and i also dont want to make a living out of it. Im just a curious Student who thinks its an interesting hobby to build my own Speakers. Im Invested in it and i want to learn as much as i can. If you dont want to help because your to insecure to respond to a followed question i have to your post then just save your time and energy the next time and dont reply at all. If you dont think its strange that there are 2 different Graphs describing the same driver and now trying to make me look dumb i dont know why you answered in the first place. Have a good day sir
Your right, im not an expert, and i also dont want to make a living out of it. Im just a curious Student who thinks its an interesting hobby to build my own Speakers. Im Invested in it and i want to learn as much as i can. If you dont want to help because your to insecure to respond to a followed question i have to your post then just save your time and energy the next time and dont reply at all. If you dont think its strange that there are 2 different Graphs describing the same driver and now trying to make me look dumb i dont know why you answered in the first place. Have a good day sir 
I don't use AJHorn but i suspect that similar to hornresp it does not include directivity effects in the standard energy response output.
the manufacturer chart however is the on-axis spl (sound pressure, not sound energy) response.
That may be an additional factor for seemingly strange simulation results.
Edit: I should probably have said "sound power" instead of "sound energy", by the way!
the manufacturer chart however is the on-axis spl (sound pressure, not sound energy) response.
That may be an additional factor for seemingly strange simulation results.
Edit: I should probably have said "sound power" instead of "sound energy", by the way!
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I'm not familiar with AJHorn, so I can't help with that. I use Tolvan Data's Basta for this type of modelling. It's pretty easy to learn.
Here's the response I get for your driver in an 18 litre sealed box with 300mm square baffle, no crossover.
It's as you'd expect, I think. Response rises because of the baffle step. Here's the response with a simple 2nd order electrical passive crossover, aiming at 500 Hz. You'll note that the impedance has dropped quite low.
Here's the response I get for your driver in an 18 litre sealed box with 300mm square baffle, no crossover.
It's as you'd expect, I think. Response rises because of the baffle step. Here's the response with a simple 2nd order electrical passive crossover, aiming at 500 Hz. You'll note that the impedance has dropped quite low.
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