Unfortunately, I don't think a gentle 1st order on the SB65 will do.
It distorts quite a bit under 300Hz. So, if I try to cross around 500Hz, it will still have some distortion. I'll need something steeper.
I will put a 2nd order on the SB65, and see if I stay with a 1st order, or go with a 2nd order on the woofers as well.
It distorts quite a bit under 300Hz. So, if I try to cross around 500Hz, it will still have some distortion. I'll need something steeper.
I will put a 2nd order on the SB65, and see if I stay with a 1st order, or go with a 2nd order on the woofers as well.
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Been mostly sunny and great weather around here, so, we stayed outside most of our vacation. Best weather we've had in many years.
But, a little break and rainy today, so I decided to come up with a little something... should be finished today.
PS. Really weird how pictures taken with an iPhone almost always have the wrong orientation in the forum, although it looks fine when I look at it on my computer.
But, a little break and rainy today, so I decided to come up with a little something... should be finished today.
PS. Really weird how pictures taken with an iPhone almost always have the wrong orientation in the forum, although it looks fine when I look at it on my computer.
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So far so good....
I have been listening to paper cones for a long while now... the alu cone of the SB65 will take a little while to dig.
The angles of the woofers didn't do much.
I still need to be at 0.2ms delay on the tweets.
If I can't find a waveguide for these SB65, I guess I'll have to stay active.
But I'm not done yet...
I have been listening to paper cones for a long while now... the alu cone of the SB65 will take a little while to dig.
The angles of the woofers didn't do much.
I still need to be at 0.2ms delay on the tweets.
If I can't find a waveguide for these SB65, I guess I'll have to stay active.
But I'm not done yet...
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Great idea to angle the woofers for setback!
If you use the big waveguide Bushmeister and I used, you will get perhaps too much setback?
A Bookshelf Multi-Way Point-Source Horn
If you use the big waveguide Bushmeister and I used, you will get perhaps too much setback?
A Bookshelf Multi-Way Point-Source Horn
Thanks, I thought it might work, and I quite like the looks of the angled woofers, but it doesn't work.
If I run all driver's the same, I still get a notch at the XO point.
Inverting the tweet gets me back to a flat FR but the Step and Impulse response is messed up.
But if I keep the same polarity and add 0.2m/s delay, I get a nice straight flat FR at the XO point.
Basically the same as the straight baffle that also needed to add 0.2ms.
Now, 0.2ms is about 6~7cm (2.5"). The Bushmeister horn will be way too deep.
I'd like to get my hands on something like this...
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And this was the project for today.
Now, either I'm going nuts or there's a problem somewhere in the measuring chain. So, I've measured other speakers I have and knew, and it checks out.
I made a stepped baffle for the woofers, this one is about 4cm thick.
And it made no changes to the measurements. I still have a big dip at the XO point.
If I add the same 0.25ms delay on the tweet, then it's back to good looking.
So, either a flat baffle, angled woofers or stepped baffle, I get the exact same delay of 0.25ms to get a good summing of the drivers.
Sorry, I don't have pretty graphs to show as I got upset that nothing changed, and deleted the REW measurements.
Also, the SB65 doesn't like the angled or stepped baffle. It messes up the higher end. Best looking FR was on a flat baffle.
So far, it looks like active is the way to go.
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0.25ms x 342m/sec=8.55cm=3.4in. You are off by an inch and it’s not just the baffle distance. It is acoustic center distance (approx distance from voice coil of woofer and voice coil of SB65). There is already about 3in offset. So you need this plus 3.4in - perhaps 6.4in total. In which case, the XT waveguide is perfect. You can measure that by taking 3 sweeps (woofer plus tweeter, woofer only, tweeter only). Then load measured responses into XO sim sofotware and adjust delay until interference pattern matches exactly. Although I am not sure if your 0.25ms is based on your measurements already which inkcues rhe acoarocbcenter offset already. In which case add another inch of offset. Just put SB65 on small flat open baffle and slide back and forth until dip goes away.
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Yep, I get that.
It's just strange that on a flat baffle, the delay needs to be at 2.5ms, and on the angled or stepped baffle, the delay needs to be at 2.5ms as well...
It should have changed a little, but it stayed there.
It's just strange that on a flat baffle, the delay needs to be at 2.5ms, and on the angled or stepped baffle, the delay needs to be at 2.5ms as well...
It should have changed a little, but it stayed there.
Been talking about the Step Response and transient a lot, but I forgot to talk about the sound.
The little SB65 is amazing with stringed instruments. Guitars, pianos, and especially violins are to die for in terms of realism. Details of the strings and the resonance of the instrument are all there.
Woodwinds and vocals are a bit ... edgy. I much prefer the "warmth" of a paper cone there.
But, with the dual 5x8", and the SB65, electronica is very engaging. The imaging of the SB65 and details make it super fun with panning stuff often used with electronica, like Massive Attack, Daft Punk and Infected Mushroom. The bass line is strong, and the highs whirlwind around your head!
The little SB65 is amazing with stringed instruments. Guitars, pianos, and especially violins are to die for in terms of realism. Details of the strings and the resonance of the instrument are all there.
Woodwinds and vocals are a bit ... edgy. I much prefer the "warmth" of a paper cone there.
But, with the dual 5x8", and the SB65, electronica is very engaging. The imaging of the SB65 and details make it super fun with panning stuff often used with electronica, like Massive Attack, Daft Punk and Infected Mushroom. The bass line is strong, and the highs whirlwind around your head!
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very interesting project and a thorough approach such as this inspires others. I don’t think I’ve seen any FAST projects based on the two-woofer arrangement before.
Thanks Bigun!
It was a crazy idea when I saw the racing track woofer, and pushed forward by Byrtt, who has moved to the software forum lately, following his new love of VituixCAD... 🙂 We miss him around here! 🙂
I'll keep at it!
It was a crazy idea when I saw the racing track woofer, and pushed forward by Byrtt, who has moved to the software forum lately, following his new love of VituixCAD... 🙂 We miss him around here! 🙂
I'll keep at it!
Question: As it's an MTM, could the woofers be spaced far enough away that a 4" or 6" waveguide could be fitted on the front of the SB65? Would have to be 3D printed I'm thinking.
Yes, the idea of a waveguide to place the SB65 farther back and try to time align the system has been put forward, but I haven't found one yet, and do not have access to a 3D printer.
Also, it would probably mess up the radiation pattern that MTM have.
Can't have everything, it seems.
Also, it would probably mess up the radiation pattern that MTM have.
Can't have everything, it seems.
How big is the volume for the SB65? In simulation it seems that they require quite a big volume to get a lowish total Q.
It's got a big VAS. RS180-4 models around 300-330cm2 in 1.2M for me. This one looks like it could use more elbow room.... 400cm2?
I had a play in LATL. Bigger CSA seems to do some good things and playing with the port length to get more extension without a "huge one note hump".
Currently I'm at 420cm2 with a 75cm2 x 30cm port. Length is still 1.3M. Port is offset at 114cm to hide some lumps.
