Hey, sorry to drag up something that was discussed much earlier in this thread but I'm thinking of building the smaller version of this speaker that jerome69 developed (thanks jerome!). This will be located on my desk and to keep costs down I'll be going with the original drivers. Suggested crossovers for this version can be seen back on page 13:
http://www.diyaudio.com/forums/multi-way/110583-fast-fun-inexpensive-ob-project-13.html
My queery regards the effect of having the woofer mounted so close to what is effectively the floor (the desk). My vague understanding is that I will have some increased bass response but I'm not entirely sure on this. Am I likely to require revisions to the crossover at all? Will a change in L1 be sufficient to tame any increased bass?
I hope to get some responses here, people seem to know much more than myself. I've only read about open baffle speakers so thinking the best way to learn is to get my hands dirty and build some. This project seems ideal.
Cheers, Josh.
http://www.diyaudio.com/forums/multi-way/110583-fast-fun-inexpensive-ob-project-13.html
My queery regards the effect of having the woofer mounted so close to what is effectively the floor (the desk). My vague understanding is that I will have some increased bass response but I'm not entirely sure on this. Am I likely to require revisions to the crossover at all? Will a change in L1 be sufficient to tame any increased bass?
I hope to get some responses here, people seem to know much more than myself. I've only read about open baffle speakers so thinking the best way to learn is to get my hands dirty and build some. This project seems ideal.
Cheers, Josh.
Hey Josh -
You will get some bounce off the desk. The desktop will act as a sort of acoustic mirror giving you a virtual second woofer. This is good and bad. Having more bass because of the reflection is good, but the reflection can add peaking at certain frequencies - that's bad.
You might try modeling your setup with Edge or Basta software and add a second woofer down below to see what it does to the response. You can model the original, then the smaller version, then your version to get a feel for those. Then model one that is twice as tall with an extra woofer below, as tho the desk were a mirror and you see your baffle and its reflection. That will give you an idea of what's going to happen on the desk.
From there adjustments to the crossover can be made.
You will get some bounce off the desk. The desktop will act as a sort of acoustic mirror giving you a virtual second woofer. This is good and bad. Having more bass because of the reflection is good, but the reflection can add peaking at certain frequencies - that's bad.
You might try modeling your setup with Edge or Basta software and add a second woofer down below to see what it does to the response. You can model the original, then the smaller version, then your version to get a feel for those. Then model one that is twice as tall with an extra woofer below, as tho the desk were a mirror and you see your baffle and its reflection. That will give you an idea of what's going to happen on the desk.
From there adjustments to the crossover can be made.
Hi Josh,
No change on the crossover. The bass will be more flat and extended. The desk effect will be up to 500Hz and compensate partially the dipole effect in the lower octave. I cannot predict what will happen in the midrange as had said Pano.
If you feel it misses treble, just decrease the resistance R2 on the tweeter.
Fell free to share your feeling on the loudspeaker
No change on the crossover. The bass will be more flat and extended. The desk effect will be up to 500Hz and compensate partially the dipole effect in the lower octave. I cannot predict what will happen in the midrange as had said Pano.
If you feel it misses treble, just decrease the resistance R2 on the tweeter.
Fell free to share your feeling on the loudspeaker
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Just looking at picking up the crossover components for the mini-manzanita and I've got a couple of questions about the inductors being used.
Do they need to be aircore?
Do they need to be a certain gauge?
Would something like these be suitable for the 10mH and 15mH components?
Jantzen 15mH 15 AWG P-Core Inductor | Parts-Express.com
Jantzen 10mH 15 AWG P-Core Inductor | Parts-Express.com
Do they need to be aircore?
Do they need to be a certain gauge?
Would something like these be suitable for the 10mH and 15mH components?
Jantzen 15mH 15 AWG P-Core Inductor | Parts-Express.com
Jantzen 10mH 15 AWG P-Core Inductor | Parts-Express.com
I have tested (and now own) the manzanita with the tdfc tweeter now
Great sound! Thank you John for a great and simple design and thank you panomaniac for posting and staying active on the project
Now the technical stuff:
I did try some filter tweaking back and forth; in the end the filter was edited just a slight tad. Changed the tweeter cap too 15uF and i added a 22uF cap in parallel with the woffer. The end result was a bit higher THD in the 2-3khz area, and much better controlled/suppressed breakup of of the sls woffer(about 15dB down). Seems like i got a little bit better phase correlation between the drivers too.
I should mention that the baffle i use are not too the same specs as the original. Its a bit taller, and the distance between the drivers are about 40cm/16inc(center-center). This is not ideal, I know, but its good enough for my testing purpose so far...
Has anyone else done something similar? with good result?
I can post some pics of my measurements later if anyone is interested
Great sound! Thank you John for a great and simple design and thank you panomaniac for posting and staying active on the project
Now the technical stuff:
I did try some filter tweaking back and forth; in the end the filter was edited just a slight tad. Changed the tweeter cap too 15uF and i added a 22uF cap in parallel with the woffer. The end result was a bit higher THD in the 2-3khz area, and much better controlled/suppressed breakup of of the sls woffer(about 15dB down). Seems like i got a little bit better phase correlation between the drivers too.
I should mention that the baffle i use are not too the same specs as the original. Its a bit taller, and the distance between the drivers are about 40cm/16inc(center-center). This is not ideal, I know, but its good enough for my testing purpose so far...
Has anyone else done something similar? with good result?
I can post some pics of my measurements later if anyone is interested
Here it comes: dont put to much value into my measurements as they are done in a "not ideal room" at all, espesially the thd since the S/N in my room where only about 40-45dB during the measurement. You can however use them to see simple trends
All measurements are shown with 1/12 octave smoothing.
pic 1: shows the woofer amplitude with and without the extra capacitor.
pic 2: shows phase w/wo extra cap.
pic 3: (sort of) shows the THD w/wo extra cap.
pic 4: shows the tweeter and woffer response with my mods
pic 5: shows the tweeter and the two woofer filter versions phase.
Mabe I will ad a picture of the baffle the drivers are mounted in a bit later. And mabe even a xo schema so there will be no confusion to what i have done
All measurements are shown with 1/12 octave smoothing.
pic 1: shows the woofer amplitude with and without the extra capacitor.
pic 2: shows phase w/wo extra cap.
pic 3: (sort of) shows the THD w/wo extra cap.
pic 4: shows the tweeter and woffer response with my mods
pic 5: shows the tweeter and the two woofer filter versions phase.
Mabe I will ad a picture of the baffle the drivers are mounted in a bit later. And mabe even a xo schema so there will be no confusion to what i have done
Attachments
Thanks for posting your measurements...very informative
Appreciate your sharing your measurements. Have often thought about a narrow trap for the Peerless centered around 2.1K. About 6-9 db of depth would do the trick. But the cap you have selected does obviously help and is inkeeping with my original "KISS" design theme.
John
Appreciate your sharing your measurements. Have often thought about a narrow trap for the Peerless centered around 2.1K. About 6-9 db of depth would do the trick. But the cap you have selected does obviously help and is inkeeping with my original "KISS" design theme.
John
Mabe I will ad a picture of the baffle the drivers are mounted in a bit later. And mabe even a xo schema so there will be no confusion to what i have done
I'd love to see what you've done with the baffle/driver mounting.
I'm in the process of building the mini version of these speakers. I'm at that lovely stage where components are starting to arrive left right and centre!
What is the model number for the woofer? Where do you get the Scan Speak? I can find a 3806 at Madisound (194$...)
Am I to presume that the dimensions of the baffle are the same as in the original proposal?
Looks like the components for the original design are still available. Is that design considered superseded now?
Peter
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There are some variations of the manzanita dimensions in the entire thread.
The original, John's in the first page It is a shape from the seventies.
Mine A monitor shape.
urkain87's but not known
Michaël's disposition
Not exhaustive ...
According to John, the version with the scanspeak 3806 is the best version because this tweeter can go low without too much stress.
The original, John's in the first page It is a shape from the seventies.
Mine A monitor shape.
urkain87's but not known
Michaël's disposition
Not exhaustive ...
According to John, the version with the scanspeak 3806 is the best version because this tweeter can go low without too much stress.