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SB Acoustics SB65WBAC25-4 - What to do?
SB Acoustics SB65WBAC25-4 - What to do?
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Old 20th August 2015, 03:01 AM   #11
xrk971 is offline xrk971  United States
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SB Acoustics SB65WBAC25-4 - What to do?
Neat idea for a small monitor using multiples. You will have a bit of comb filtering and lobing in vertical direction but may not be a big deal to you. What XO frequency were you planning on given the baffle edge diffraction you predict?
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Old 20th August 2015, 03:24 AM   #12
jeshi is offline jeshi  Japan
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Yeah I suspected that the line-array would do that in the vertical, but the lobbing should be good. These sort of monitors are usually placed on a meter bridge or just above a music keyboard or other desk items, so there can be terrible reflections coming off all the irregular shapes directly below and in front of the monitor. Kind of like these sort of setups.
Click the image to open in full size.
Click the image to open in full size.
The comb effect, well... I hope with such small drivers and mounting them end-to-end (64mm center-to-center), it might minimize the effect. Ideally I would put a 30cm long linear ESL on the side of the box (like a mini version of my acoustat 1+1), but the thought of DIY building an ESL panel is just a bit too much for me at this point. I think a 2x or 3x line array of small drivers might get close enough.

I am not sure about the crossover yet. I need to see the response and distortion on the slot-loaded woofer and what the measurements of a line array of SB65 looks like. I could see it being anything from 200-500hz depending on the performance of the drivers. My first step is to build the SLOB woofer while waiting for more SB65 to come back in stock.
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Old 20th August 2015, 04:22 AM   #13
jeshi is offline jeshi  Japan
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XRK do you know how to simulate a 3x line array of sb65 drivers? Is there free software for this?
I guess I am most interested in simulating the combing and lobbing effects to predict minimum listening distance and off axis response.

I known with PA line arrays for events that they follow a de-curve and are not flat. It also looks like the curve is not radial but an increasing curve. I wonder if with such a small array needs to curve though.

I still need to learn a lot more about line arrays


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Old 20th August 2015, 04:47 AM   #14
xrk971 is offline xrk971  United States
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SB Acoustics SB65WBAC25-4 - What to do?
Quote:
Originally Posted by jeshi View Post
XRK do you know how to simulate a 3x line array of sb65 drivers? Is there free software for this?
I guess I am most interested in simulating the combing and lobbing effects to predict minimum listening distance and off axis response.

I known with PA line arrays for events that they follow a de-curve and are not flat. It also looks like the curve is not radial but an increasing curve. I wonder if with such a small array needs to curve though.

I still need to learn a lot more about line arrays


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Yes, you can model it with my software of choice: Akabak. I have modeled the 25 driver IDS-25 with TC9FD's below. You can see the comb effect at various drivers. You will need an archaic Windows machine (pre 64 bit) - XP or W2K. The software has a learning curve but start small and work your way up in complexity. It's a script programming language that uses JIT compilation. There is some window dialog automation but not a whole lot. I can get you the script for the 25 driver array. To model your OB with 3 drivers is pretty simple. I think you have a trapezoidal baffle so that can be simulated with a different baffle width for each driver position. It will give you pretty close results. I have also modeled the SLOB with Akabak as well.

Click the image to open in full size.

Model of 25 driver line array here:
Cloning IDS-25s

Akabak here:
http://www.randteam.de/AkAbak/Index.html

Akabak for Dummies:
http://www.avsforum.com/forum/155-di...topics/1258118

Good tutorial by Don Hills:
Akabak Simulator

Most of the basic guides will not get into the fine points of modeling an OB and how to handle edge diffraction and placement of drivers on baffle. But I can help you there.

Last edited by xrk971; 20th August 2015 at 04:55 AM.
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Old 8th December 2017, 10:13 AM   #15
arcgotic is offline arcgotic  Romania
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What internal volume for a closed box would be optimal for this driver?
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Old 8th December 2017, 07:20 PM   #16
Jim Griffin is offline Jim Griffin  United States
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On a SB65 in a closed box performance see:

SB Acoustics SB65WBAC25-4 2.5" full range

A volume of 0.5 to one liter provides an F3 to about 140 Hz.

My BassBox models give similar results.
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Old 16th April 2019, 08:08 PM   #17
33Polkhigh is offline 33Polkhigh  United States
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How do these sound compared to the alpair 5.2 (which I can't find measurements for anywhere). Fatiguing? What's a realistic vented f3?
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Old 16th April 2019, 08:58 PM   #18
xrk971 is offline xrk971  United States
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SB Acoustics SB65WBAC25-4 - What to do?
It sounds very neutral not fatiguing. It was one of the drivers in the Subjective Blind listening test threads and did very well. I don’t know what an A5 sounds like, but you can compare to an A7 in the listening tests.

Subjective Comparison Threads

A Subjective Blind Comparison of 3in to 5in Full Range Drivers

A Subjective Blind Comparison of 3in to 5in drivers - Round 2

A Subjective Blind Comparison of 2in to 4in drivers - Round 3

A Subjective Blind Comparison of 2in to 4in drivers - Round 4

A Subjective Blind Comparison of 2in to 3.5in drivers - Round 5
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Old 16th April 2019, 10:10 PM   #19
33Polkhigh is offline 33Polkhigh  United States
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Thanks for the reply. I think I will get a pair for some mini monitors. There are quite a few measurements showing that they don't have much nastiness up top, at least as far as I can hear. Measurements of the alpair 5.2 by comparison are few and far between.

It looks like ported is the main option for the mini sb driver, but an f3 in the 80 hz range is good considering.
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Old 17th April 2019, 12:57 AM   #20
xrk971 is offline xrk971  United States
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SB Acoustics SB65WBAC25-4 - What to do?
I really would not use them to make any bass below 150Hz - they will distort since they are tiny. Bass requires volume of air to flow. Use a subwoofer and these as satellites or in a FAST to really use them to their potential. Although of you use them at low volumes like below 80dB maybe they are fine for 80Hz.
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