So what is the question?
Looking at those Vituix plots I see flatish on-axis SPL curve (okay) and a rather low impedance and flat power response (not so okay).
Looking at those Vituix plots I see flatish on-axis SPL curve (okay) and a rather low impedance and flat power response (not so okay).
Thanks for helping.
The design uses 2xSB15CAC30-8 Bass-Mid Drivers and a Satori TW29RB HF Unit (which I assume is 4ohms) in an MTM configuration.Each 15CAC has an REof 5.7 ohms and they are connected in parallel so low resistance but ok with my amplifier.
I would like to build it but have some queries.
What do you think the baffle step is in db, the speakers will be only 50mm from a back wall and I wonder if I should reduce it and also what would I need to change.
Also if I find the treble a bit bright what should I change in that circuit.
Apart from that do you think the crossover is basically ok,
I forgot to tell you the baffle width it is 17.5 cm or175mm or 7.5 inches.
Thank you for your help.
Thank you for your help.
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Looking at this a bit more it seems that the power response curve is identical to the on-axis SPL curve. This can't be right. How did you measure the data (on axis, off axis)?
This is not something I have made yet so not my measurements.
All info is from the website where the design has been published.
I to be honest I am not sure what you mean, my questions are in my earlier post.
All info is from the website where the design has been published.
I to be honest I am not sure what you mean, my questions are in my earlier post.
Here is a link to the website of the design
As I said earlier my questions are:-
The design uses 2xSB15CAC30-8 Bass-Mid Drivers and a Satori TW29RB HF Unit (which I assume is 4ohms) in an MTM configuration.Each 15CAC has an REof 5.7 ohms and they are connected in parallel so low resistance but ok with my amplifier.
I would like to build it but have some queries.
What do you think the baffle step is in db, the speakers will be only 50mm from a back wall and I wonder if I should reduce it and also what would I need to change.
Also if I find the treble a bit bright what should I change in that circuit.
Apart from that do you think the crossover is basically ok,
The baffle width it is 17.5 cm or175mm or 7.5 inches.
Thank you for your help
As I said earlier my questions are:-
The design uses 2xSB15CAC30-8 Bass-Mid Drivers and a Satori TW29RB HF Unit (which I assume is 4ohms) in an MTM configuration.Each 15CAC has an REof 5.7 ohms and they are connected in parallel so low resistance but ok with my amplifier.
I would like to build it but have some queries.
What do you think the baffle step is in db, the speakers will be only 50mm from a back wall and I wonder if I should reduce it and also what would I need to change.
Also if I find the treble a bit bright what should I change in that circuit.
Apart from that do you think the crossover is basically ok,
The baffle width it is 17.5 cm or175mm or 7.5 inches.
Thank you for your help
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Take a look at your minimum impedance. The 2nd order devices you have need a little resistor after them. Usually around half an Ohm to 1 Ohm.
I do think the system is a little bright. The level of the tweeter is a little high, and the high pass filter points it upwards. You want the tweeter flat or downwards, and when you are done there, you'll probably want to reduce the overall level somewhat.
I do think the system is a little bright. The level of the tweeter is a little high, and the high pass filter points it upwards. You want the tweeter flat or downwards, and when you are done there, you'll probably want to reduce the overall level somewhat.
Ok, I see. The graphs show the on-axis SPL curve (black curve in the "SPL" panel at the top) and the power response (blue curve in the "power & DI" panel). Looking at the two curves, they are offset by a few dB, but otherwise IDENTICAL. This can't be right. I don't speak Polish, so I don't understand the thread you linked and can't tell how these data were taken. However, I believe the off-axis response data were not measured at all and were just assumed to be the same as the on-axis SPL response. This will of course give a very wrong power response curve. It is therefore impossible to tell anything about the sound balance of this speaker.
Hi everyone thanks for your replies and help so far.
I used Google to translate the Polish to English.
The designer does actually comment on the fact that the speakers are bright and that he changed the crossover as he felt they sounded dark.
I have posted on that site with my questions but there have been no answers so far thats why I came here knowing there is a lot of knowledge.
With regard to eriksquires comment about fitting a small resistor to increase the impedance I am not sure where it should be fitted. Also will it alter the sound of the speakers.
I would still wellcome answers to my earlier questions:-
What do you think the baffle step is in db, the speakers will be only 50mm from a back wall and I wonder if I should reduce it and also what would I need to change.
Also if I find the treble a bit bright what should I change in that circuit.
Apart from that do you think the crossover is basically ok,
The baffle width it is 17.5 cm or175mm or 7.5 inches.
I used Google to translate the Polish to English.
The designer does actually comment on the fact that the speakers are bright and that he changed the crossover as he felt they sounded dark.
I have posted on that site with my questions but there have been no answers so far thats why I came here knowing there is a lot of knowledge.
With regard to eriksquires comment about fitting a small resistor to increase the impedance I am not sure where it should be fitted. Also will it alter the sound of the speakers.
I would still wellcome answers to my earlier questions:-
What do you think the baffle step is in db, the speakers will be only 50mm from a back wall and I wonder if I should reduce it and also what would I need to change.
Also if I find the treble a bit bright what should I change in that circuit.
Apart from that do you think the crossover is basically ok,
The baffle width it is 17.5 cm or175mm or 7.5 inches.
I forgot to say I am going deaf so brightness is not a problem it's the baffle step that concerns me most.
I can't show your circuit because the picture is too huge, but the bafflestep looks OK. So does the bass circuit in general. I do see a RC notch there which might be dipping impedance low. Do you need it?
But the tweeter filter is plain dangerous dipping to 2.5 ohms at 3kHz.
You need to redesign it IMO.
Vifa PL14WJ-
Put resistance in front of the filter somehow. At least 4 ohms minimum required. Tweeter level is easily adjusted with the same resistor.
But the tweeter filter is plain dangerous dipping to 2.5 ohms at 3kHz.
You need to redesign it IMO.
Vifa PL14WJ-
Put resistance in front of the filter somehow. At least 4 ohms minimum required. Tweeter level is easily adjusted with the same resistor.
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Hi Steve thanks for your input.
I know little about crossovers so dont really know how to change things it was actually designed by someone else.
Not sure where to go from here.
I know little about crossovers so dont really know how to change things it was actually designed by someone else.
Not sure where to go from here.
The thing is with this design is the high WAF also I dont have a large lounge and therefore a small MTM or 2.5 way is ideal.
The only other speaker I can find is the SEAS Delling but of course its a lot more expensive.
The only other speaker I can find is the SEAS Delling but of course its a lot more expensive.
I notice most of the 2 way and MTM designs on the site I referred to as having very low impedance.
Can someone help me increase the impedance, i.e. where should resistors be placed and values.
Thanks
Can someone help me increase the impedance, i.e. where should resistors be placed and values.
Thanks
That is a nice loudspeaker for the most part:
MTM 2xSB15CAC30-8 & TW29RB - projekt by borys
But using metal bass parallel on an MTM is difficult on impedance because the RC notch makes things even worse. A better way is to use 2X 4 Ohm bass wired in series:
Tritrix_pg_1
Speaker Design Works
Everything is then easy. Impedance is never less than 7 Ohms.
MTM 2xSB15CAC30-8 & TW29RB - projekt by borys
But using metal bass parallel on an MTM is difficult on impedance because the RC notch makes things even worse. A better way is to use 2X 4 Ohm bass wired in series:
Tritrix_pg_1
Speaker Design Works
Everything is then easy. Impedance is never less than 7 Ohms.
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JulyHi Steve
Thanks for your reply. I see your point regarding impedance. SB actually do a 4ohm version of the 15CAC bass Unit and I am sure an 8 ohm version of the Satori tweeter is available but I have no idea how to design a crossover so I suppose this is now the end of the road of this design for me.
Thanks for your reply. I see your point regarding impedance. SB actually do a 4ohm version of the 15CAC bass Unit and I am sure an 8 ohm version of the Satori tweeter is available but I have no idea how to design a crossover so I suppose this is now the end of the road of this design for me.
I googled the word... thought it might be a Polish greeting... 😀
Anyhow, I have delved in the archive and dug up an early SB Acoustics Elok design which looks better. 20cm wide baffle, 21 Lires, 7 cm x 15 cm reflex tube. Actually an MTM, but you can change that.
The VAS of the Qts 0.33 midbass is a whopping 21L so you can certainly go bigger.
The paper/nextel drivers are superceded, but the newer midbass is very similar.
5″ SB15NRX2C30-8 / Norex – Sbacoustics
Maybe a dB quieter. I couldn't find a design using those 15CAC metal drivers, so best avoided.
I think you could use any SB tweeter you fancy by adjusting R1 for level. It's doable, IMO.
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