Alright! Way to go Silent, now you're getting somewhere. Seeing those 12MU mounted like that makes me think it's not necessary at all. This whole backwards mounting is great for woofers, but I think due to the small size of the cone and the shading of the magnet that it will cause more problems for you as regards to radiation than it really solves with 2nd harmonic distortion. I'd personally go with both facing forward. At least that one's an easy switch to make.
Thanks guys, will fix some of those issues up in first round of modifications.
The 3/4" MDF I used is a bit thick for the mids (not to mention poor time allignment on the woofer).
The 30 degree chamfer on the mids unshrouds them quite nicely, but I think they would be much happier in someting like a 1/2" piece of MDF instead, which I have laying around, or possibly even thinner.
When the dipole tweeters turn up I will move the tweeter and mids to a separate board and step it back from the main board.
Thinking of cutting out a big square so I leave an edge around the 3/4" MDF, step the smaller board back with 4 long bolts.
Seem to have picked up some bass with mounting it on the board (as expected) going to drop the xover point from 300 to 150 as it sounds like there is a tad too much bass (bit to much pronounced drum in the music I am listening to - The Cars) The SPL mix is quite good as no driver seems to be shouting at me, at turn on volume (quite low) each of the drivers sounds quite even.
The tweeter sounds a bit more tinny that before and not quite as natural. But I haven't adjusted the xover just yet to give me chance to evaluate the change.
The 3/4" MDF I used is a bit thick for the mids (not to mention poor time allignment on the woofer).
The 30 degree chamfer on the mids unshrouds them quite nicely, but I think they would be much happier in someting like a 1/2" piece of MDF instead, which I have laying around, or possibly even thinner.
When the dipole tweeters turn up I will move the tweeter and mids to a separate board and step it back from the main board.
Thinking of cutting out a big square so I leave an edge around the 3/4" MDF, step the smaller board back with 4 long bolts.
Seem to have picked up some bass with mounting it on the board (as expected) going to drop the xover point from 300 to 150 as it sounds like there is a tad too much bass (bit to much pronounced drum in the music I am listening to - The Cars) The SPL mix is quite good as no driver seems to be shouting at me, at turn on volume (quite low) each of the drivers sounds quite even.
The tweeter sounds a bit more tinny that before and not quite as natural. But I haven't adjusted the xover just yet to give me chance to evaluate the change.
Did a bit of cabinet designing today for my next experiment. To protect the driver from accidental damage I have come up with a very simple horn version of the standard H box.
All that had been added are 4 corner braces that will strengthen and turn the front cavity into a octagon, whilst using the 4 existing sides to make up the eight sides, it also gives four convient locations to mount a speaker grill.
All that had been added are 4 corner braces that will strengthen and turn the front cavity into a octagon, whilst using the 4 existing sides to make up the eight sides, it also gives four convient locations to mount a speaker grill.
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My only concern is the shape of the back of the cone is the reverse of the front, so the rear of the cone is angled towards the walls of the cabinet.
I don't know if this will actually cause any reflection issues if I start crowding the back of the cone. On the front the horn is the same shape as the cone, on the back it is opposite.
I don't know if this will actually cause any reflection issues if I start crowding the back of the cone. On the front the horn is the same shape as the cone, on the back it is opposite.
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Fair enough... Because they would be additonal support pieces I could just build the standard box and simply add them later, which would give me chance to measure with and without them.
Because the box isn't going to be sealed and subject to as much vibrations, how thick does a H box need to be? walls? main driver panel?
Because the box isn't going to be sealed and subject to as much vibrations, how thick does a H box need to be? walls? main driver panel?
Added one of the Vifa hard paper 10"'s into the baffle today. I know they are fairly useless in their own right but I thought since I had them I would throw one in to see if it can fix up a small hole between the woofer and the 12MU's.
I am only using it between 150Hz and 625Hz and I must say it does a great job of smooting out the bass.
Currently I have the Raal 140-15D AM tweeter covering 2500Hz up
The ScanSpeak 12MU mids between 625Hz and 2500Hz
The Vifa 10" between 150Hz and 625Hz
The Tc Sounds Pro 5100 between 25Hz and 150Hz
The Raal dipoles should be here Monday.
So what does it sound like? I for one thought I would never be happy listening to just one speaker, but it sounds so great it's pleasurable.
If I close my eyes I could almost be fooled into thinking there are several speakers hooked up it just has a spacial quality like nothing I have ever heard before.
When people say dipoles are great for bass I definately know what their talking about now, its like chalk and cheese.
I am only using it between 150Hz and 625Hz and I must say it does a great job of smooting out the bass.
Currently I have the Raal 140-15D AM tweeter covering 2500Hz up
The ScanSpeak 12MU mids between 625Hz and 2500Hz
The Vifa 10" between 150Hz and 625Hz
The Tc Sounds Pro 5100 between 25Hz and 150Hz
The Raal dipoles should be here Monday.
So what does it sound like? I for one thought I would never be happy listening to just one speaker, but it sounds so great it's pleasurable.
If I close my eyes I could almost be fooled into thinking there are several speakers hooked up it just has a spacial quality like nothing I have ever heard before.
When people say dipoles are great for bass I definately know what their talking about now, its like chalk and cheese.
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You know, your implementation here looks pretty nice Silent. Simple.
I'm not too familiar with the RAAL driver though. I once tried my Heil on a baffle and it destroyed the sound of it. Open air mounting sounds the best with those. Do you have a similar observation with the RAAL? If so, I could see where a guy could modify your arrangement in #249 to limit the baffle @the tweeter/mid area.
Siding the RAAL over (so it's almost plumb with the C/L of the 10" driver) and siding over one of the 12MU's toward the RAAL's bottom edge. Then cut off the waste baffle.
Looking good as is though!
I'm not too familiar with the RAAL driver though. I once tried my Heil on a baffle and it destroyed the sound of it. Open air mounting sounds the best with those. Do you have a similar observation with the RAAL? If so, I could see where a guy could modify your arrangement in #249 to limit the baffle @the tweeter/mid area.
Siding the RAAL over (so it's almost plumb with the C/L of the 10" driver) and siding over one of the 12MU's toward the RAAL's bottom edge. Then cut off the waste baffle.
Looking good as is though!
Yes that was my observation too. The Raal / 12MUs lost their beautiful natural sound and become quite tinny sounding on the wide baffle. I dropped the xover back from 4000 to 2500 and it helped a lot.
This is only a test baffle but if I was staying with these drivers I would narrow the baffle around the tweeter and mids.
I was hoping the new Raal 140-15D AM dipoles would have turned up yesterday but they got posted too late. I'm leaving the baffle as is for now so I can try the dipoles in the same arrangement, then I will start on a new baffle with H box on the bottom.
Not sure what I will replace the 10" Vifas with yet but will look at that after the H box is done to see if they are still required.
Extremely happy with the sound so far.
This is only a test baffle but if I was staying with these drivers I would narrow the baffle around the tweeter and mids.
I was hoping the new Raal 140-15D AM dipoles would have turned up yesterday but they got posted too late. I'm leaving the baffle as is for now so I can try the dipoles in the same arrangement, then I will start on a new baffle with H box on the bottom.
Not sure what I will replace the 10" Vifas with yet but will look at that after the H box is done to see if they are still required.
Extremely happy with the sound so far.
Sure they will be more required. A H frame cannot be use after 100Hz.
Perhaps you will have to cut below 100Hz.
100hz is not a hard and fast number. It depends in the dimensions(depth) of your H. See here for 1/4 wavelength calculations to determine it's resonant frequency:
http://www.quarter-wave.com/OBs/U_and_H_Frames.pdf
No you can't go lower than 800Hz with one 4", there is a relation (known by experiment) with the surface and the point of crossover (to minimize distortion), in an OB you move air and you need surface. Perhaps you can go near 400Hz with 2x12MU ?
Yes 100Hz is an experimental approximative number when you use 2x10" in the H Frame
It is just a point of reference for discussion.Imagine a 18", bigger the point will be lower.
I am not very agree with that, I think an octave below the dipole peak
But if you ears support this that is OK. Mine not.
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