Okay I just picked up 3 sheets of 9ply BB, and I have all of my materials on order. Should arrive tomorrow
Building two SynTripP's
From Anderson Plywood:
3 sheets baltic birch @ 4'x8' (B/BB) - got a little extra there
From McmasterCarr:
M4 tee nuts
M4 pan head bolts, 18mm length
4.7mm drill bit (to pilot for tee nuts)
24mm x 4mm (1" x 1/8") closed cell acrylic foam tape (for back plate seal)
8x draw latches for securing secondary horn
Already have:
4x B&C 10CL51
2x FaitalPro HF144 Compression Drivers
Only question I have is if the HF144 will suffice? It has a 1.4" throat
Building two SynTripP's
From Anderson Plywood:
3 sheets baltic birch @ 4'x8' (B/BB) - got a little extra there
From McmasterCarr:
M4 tee nuts
M4 pan head bolts, 18mm length
4.7mm drill bit (to pilot for tee nuts)
24mm x 4mm (1" x 1/8") closed cell acrylic foam tape (for back plate seal)
8x draw latches for securing secondary horn
Already have:
4x B&C 10CL51
2x FaitalPro HF144 Compression Drivers
Only question I have is if the HF144 will suffice? It has a 1.4" throat
Fin,
I used 1/4" Baltic Birch plywood laminated to 1/4" aluminum for a total depth of 1/2" for the throat adapter, as can be seen in post #250 (and several postings before..).
Art
9 Ply is thinner than the 1/2" I used, don't recall what Fin used. 9mm BB is probably still stiffer (and heavier) than the plywood I used.
The FaitalPro HF144 uses a 2.56" diaphragm rather than 3", so will have less output in the crossover region. The excursion below 900 Hz limits the amount of power that can be used before hammering the diaphragm on the phase plug to about 40 watts, which still is quite loud.
Art
Jenny,
Your diagram does not show the SynTripP throat as I designed and built it, as can be seen in the photos and plans previously posted.
If built like that, the HF driver low frequency loading will be compromised (excursion for a given drive voltage will be higher, output will be less than as designed), and polar response will be "different".
Art
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I see.
What is the cause of that?
Is it because of the HPF effect of a conical horn? Being that the closer towards the throat you get the higher the cutoff frequency gets?
Side views showing transition using 24mm throat adapter. No sudden expansion in either dimension.
As shown, some material would be removed from horn to match throat adapter's convexity. Maybe not necessary with a thicker (24mm) throat adapter? I.e. the entire transition from rectangle to circle could be contained within the adapter instead of having to remove material from the horn?
If that doesn't make sense, happy to draw up an example
As shown, some material would be removed from horn to match throat adapter's convexity. Maybe not necessary with a thicker (24mm) throat adapter? I.e. the entire transition from rectangle to circle could be contained within the adapter instead of having to remove material from the horn?
If that doesn't make sense, happy to draw up an example
Attachments
1) A thicker adapter will cause high frequency narrowing in the horizontal beamwidth.
2) That could be done if the horn was shortened, but then the spacing of the 10" to the HF would need to be increased.
Fin,
A conical horn is not really a HPF, it is more of a waveguide. The HF drop off is typical of any constant directivity horn, representative of the raw HF driver response.
The diagram in #263 shows a parabolic throat expansion. A parabolic expnsion has less loading near Fc than a conical expansion.
Art
Art, thanks for your direction!
May I ask you to draw (not necessarily to scale) a top-down view/representation of the expansion from the CD through the throat adapter to the greater part of the horn? The plan drawing in post 41 does not seem to match build photo, which looks to have a wider [horizontal] entrance.
What I am gathering is that the horizontal expansion seems to be more of an S-curve as it transitions through the adapter. I would like to model this in a way that suits the original polar response you had intended for this design.
Meanwhile, I will be in the wood shop making jigs for the inner horn pieces
May I ask you to draw (not necessarily to scale) a top-down view/representation of the expansion from the CD through the throat adapter to the greater part of the horn? The plan drawing in post 41 does not seem to match build photo, which looks to have a wider [horizontal] entrance.
What I am gathering is that the horizontal expansion seems to be more of an S-curve as it transitions through the adapter. I would like to model this in a way that suits the original polar response you had intended for this design.
Meanwhile, I will be in the wood shop making jigs for the inner horn pieces
Can you measure the opening (distance from top corner to top corner and side corner to same side bottom corner) of your completed & built SynTripP where it meets the throat adapter? I'd like to cross compare it to Fin's 3D model and plans that I am building from. See attached
This would be a huge help. I am sensing that there may be a discrepancy in the 3D model there, and it seems like getting this right will be very important to the HF response.
This would be a huge help. I am sensing that there may be a discrepancy in the 3D model there, and it seems like getting this right will be very important to the HF response.
Attachments
Art- if you could measure the inner horn itself as built, it would be a massive help to me
Red rect - width & height of inner horn exit
blue rect - width & height of inner horn entrance (not including throat adapter)
green line - distance between the corners
This would help me a ton! I have all of the information I need to extrapolate everything else.
Red rect - width & height of inner horn exit
blue rect - width & height of inner horn entrance (not including throat adapter)
green line - distance between the corners
This would help me a ton! I have all of the information I need to extrapolate everything else.
Attachments
Jenny,
To actually measure the inside of the horn would require unloading my trailer and removing the SynTripP grill, a bit more work than I'm up for.
Completed dimensions as built are in post #61.
You should be able to extrapolate inner horn dimensions from them.
Art
Good morning, Art! Thanks for the response. Unfortunately, when I recreate the horn according to your cut sheet / drawing, the pieces do not line up near the throat entrance. Looking back, I believe Fin was running into the same problem and in the end just settled on something as close as he could get it.
This is where the difference in throat entrance dimensions is coming from. There is not enough info in the plans to be sure. The horn could be assembled with a number of different outcomes.
I could go into detail as to why, it has to do with trimming the top/bottom horn cleats after the fact. Also there is no information about mitering.
This is where the difference in throat entrance dimensions is coming from. There is not enough info in the plans to be sure. The horn could be assembled with a number of different outcomes.
I could go into detail as to why, it has to do with trimming the top/bottom horn cleats after the fact. Also there is no information about mitering.
As you can see, the horn top and bottom pieces can be placed a number of places vertically, resulting in unspecified height along the entire horn path.
Without knowing the inner horn dimensions, it is impossible to recreate what you have done without making guesses and probably severely impacting response.
Also notice the large width appearing around where the throat adapter attaches, which does not match the build photos. Well, it does for some like the photo in post 108, but not for the photo in post 250. It appears that those horns were built to different specs. Attached are the two photos
It is impossible to make a smooth transition from rectangle to circle in a .5" throat adapter in both mine and Fin's model... He said he had to make it with a bit of an S-curve because the throat entrance width was too wide for a smooth transition.
If the inner dimensions can be known, all of this is easily demystified. Hopefully you can find some time to measure the horn. Unfortunately my hands are tied until then, it seems.
Without knowing the inner horn dimensions, it is impossible to recreate what you have done without making guesses and probably severely impacting response.
Also notice the large width appearing around where the throat adapter attaches, which does not match the build photos. Well, it does for some like the photo in post 108, but not for the photo in post 250. It appears that those horns were built to different specs. Attached are the two photos
It is impossible to make a smooth transition from rectangle to circle in a .5" throat adapter in both mine and Fin's model... He said he had to make it with a bit of an S-curve because the throat entrance width was too wide for a smooth transition.
If the inner dimensions can be known, all of this is easily demystified. Hopefully you can find some time to measure the horn. Unfortunately my hands are tied until then, it seems.
Attachments
Jenny,
As mentioned before, I never have seen Fin's model (other than the rough one earlier in the thread, it has some mistakes, there should not be "a bit of an S-curve" in the throat entrance, as would be required in the too wide model shown in #278.
IIRC Fin also skipped the adjustable pole mount.
The plans in post #41 (and the photos you have re-posted) are representative of the way my SynTripP horns were built.
Art
Thanks Art, the plans get us very close- as do a lot of the other posts in this thread that you have so incredibly graciously kept up with! But, all of this leaves out some crucial details which have lead both of us to seeing a throat entrance which is not representative of your later instructions.
Without some further clarification not evident in #41 or anywhere else in this thread or the Synergy Tripp 10 thread, it is impossible to accurately reproduce the SynTripP.
Without some further clarification not evident in #41 or anywhere else in this thread or the Synergy Tripp 10 thread, it is impossible to accurately reproduce the SynTripP.