That's doubtful as there is 1in thick eggcrate foam inside and a big wad of fiberglass in the empty space.
Also a 280Hz reflection implies a 24in half-wave reflection cancellation distance. The mic is at 19in so 24in might be the reflection off the tripod stem 5in behind the mic.
Here is predicted Step Response with tweeter having a 0.75in setback:
Wait... you can place drivers on the baffle in XSim?
I didn't know that. I'll have to look it up!
An impedance plot would show if the problem comes from within the enclosure. That said, I never had any luck with that egg crate stuff.
Fiberglass insulation and wool felt absorb much much better.
While the tripod may be 24in away, it won't create a reflection at the mic at 24in, but at it's distance from the mic at 5in. It has to be something else.
Something within 24in of the mic, perhaps...
Looking at this graph:
The green response, with the offset position of the 10F, would have my preference. It will sound more balanced in stereo. While it may not seem like a large difference, there's already too much emphasis around ~3.7 kHz in a standard Stereo triangle. Perhaps it can be solved by toe-in or out.
Tiny differences like in these two plots do way more for perception than most people realize. I bet the speakers with the green trace do very well in balance as well as imaging. Though the slightly higher bottom end of the ply enclosure would be welcome.
I'd always opt for the one with better sound over looks. We build them for the music, right? I know I do!
Sorry to be so overly critical
The green response, with the offset position of the 10F, would have my preference. It will sound more balanced in stereo. While it may not seem like a large difference, there's already too much emphasis around ~3.7 kHz in a standard Stereo triangle. Perhaps it can be solved by toe-in or out.
Tiny differences like in these two plots do way more for perception than most people realize. I bet the speakers with the green trace do very well in balance as well as imaging. Though the slightly higher bottom end of the ply enclosure would be welcome.
I'd always opt for the one with better sound over looks. We build them for the music, right? I know I do!
Sorry to be so overly critical
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Thanks for the feedback Wesayso. No worries about the critique - always welcome to make things better. So this was a first measure in this new baffle. I am wondering if it is simply the new baffle centration that causes the rise at 3.7kHz? I can fool it by taping an extra piece of foam core to one side to add the "offset" baffle back and see if that helps.
Worst case, perhaps a small notch filter there might help. I will look at the backside of the 10F inside the Dagger to see if anything is there.
Worst case, perhaps a small notch filter there might help. I will look at the backside of the 10F inside the Dagger to see if anything is there.
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Look at the simulation BYRRT posted a few pages ago, it's almost an exact prediction of your measured response. Don't merely look at the distances to the cone, that's not what's causing the dip/peak combinations, it is the difference in distance of different sound paths at the microphone that counts, not to the driver itself.
That's why you cannot fix diffraction with EQ, for each angle and distance the differences of the sound paths (direct sound vs diffracted sound) will change. Diffraction is better battled by trying to avoid it.
Put in that gasket to check it, it won't fix the 3.7 ripple. It might tidy up the response a little higher up in frequency.
That's why you cannot fix diffraction with EQ, for each angle and distance the differences of the sound paths (direct sound vs diffracted sound) will change. Diffraction is better battled by trying to avoid it.
Put in that gasket to check it, it won't fix the 3.7 ripple. It might tidy up the response a little higher up in frequency.
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Actually I don’t agree that Byrtt’s prediction worked. It predicted a dip at the squiggle and the centered baffle measurement was a peak there. The use of 1/2 wave distances usually gives some insight to the cause because after all, the inverse of the frequency corresponds to a real distance - somewhere. The trick is where.
Just try it, you'll see
The plot from BYRTT showed the exact same pattern, maybe not entirely at the same spot.
That would depend on the actual measurement distance, nothing more, nothing less.
Look at this post:
http://www.diyaudio.com/forums/full-range/242171-towers-25-driver-range-line-array-409.html#post5320774
See how things change at different distances? Despite the fact that the distance between the speakers does not change? See your enclosure edge as a separate radiating source, that comb pattern is going to move too, with a different measurement distance.
Your rule of thumb is flawed once we start to look at different distances to the enclosure. It's only valid for the measurement taken with that exact distance between the speaker and microphone. Change one variable and the dip/peak is going to move.
The plot from BYRTT showed the exact same pattern, maybe not entirely at the same spot.
That would depend on the actual measurement distance, nothing more, nothing less.
Look at this post:
http://www.diyaudio.com/forums/full-range/242171-towers-25-driver-range-line-array-409.html#post5320774
See how things change at different distances? Despite the fact that the distance between the speakers does not change? See your enclosure edge as a separate radiating source, that comb pattern is going to move too, with a different measurement distance.
Your rule of thumb is flawed once we start to look at different distances to the enclosure. It's only valid for the measurement taken with that exact distance between the speaker and microphone. Change one variable and the dip/peak is going to move.
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I finally had time to finish assembly of the second Baltic birch ply FAST cabinet. Goes much faster once you know the strategy for where to apply the Noico sound dampening sheets and eggcrate sound insulation foam, where the crossover board is mounted, where to drill binding posts, etc. That is, thinking about it takes 3x longer than doing it.
Anyhow, listening to Steve Clarke drum solos on them now. This is where they shine particularly well. Transient perfect nature really captures the realism of the drum performance. Imaging, time resolution of all the beats and rimshots, high hats - wonderful treat to the ears. Powering with my new 20w ALPHA class A amp. Seems plenty of power even for these 82.4dB (2.83v at 1m at 100Hz) speakers.
Anyhow, listening to Steve Clarke drum solos on them now. This is where they shine particularly well. Transient perfect nature really captures the realism of the drum performance. Imaging, time resolution of all the beats and rimshots, high hats - wonderful treat to the ears. Powering with my new 20w ALPHA class A amp. Seems plenty of power even for these 82.4dB (2.83v at 1m at 100Hz) speakers.
A funny story about these Baltic birch FAST speakers. As I was listening to them last night my wife came down to the speaker lab (rarely ever happens) and asked to listen to the new speakers (even more rare). She played her own music and kept asking me to turn it up. It was being powered with my new Alpha 20 Class A amp so the sound was quite good. But she said they sound really really good - very clean and no distortion even when pressed loud - we were yelling to hear each other talk. Anyhow, she liked them so much she asked me to make her a pair (in dark brown espresso stain) for the living room. Her one complaint was that she said that the black colored driver cones were not a good color. Drivers should be available in choice of finish like faucets and door knobs. Antiqued brushed bronze finish would have been good.
So my first order for the new speakers - from perhaps my most hard to impress judge.
So my first order for the new speakers - from perhaps my most hard to impress judge.
I've noticed this with my versions as well, I can really crank them and they are still crystal clear and nicely controlled. The RS-225 is one heck of a driver, and for the price, even more so.
I'm about to order the 10f's, and build exposed 'daggers' for them for mine. Will likely upgrade a few crossover components then as well.
and, finally mount the crossovers inside the RS-225 boxes
Took me 2 years to get to this - the cheap XO's were sitting on top of the XPS foam cabinets. Now premium quality components on XO (polycaps, air core, non inductive resistors), mounted inside cabinet. It makes for a much nicer looking and sounding speaker. It's hard for someone like me, who used to make a new speaker every week or two, to commit to a real wooden cabinet and permanently attached XO. Glad I did it though. So, lesson for me is if a speaker lasts over 6 months in listening position as main speaker - get some real cabinets for it and move on.