Nice cabinet. Looks very professional. The work of a true craftsman. Any chance we can see some detailed construction pics of the internal panel bending and glue up process? I'm just trying to fit all the pieces together in my mind.
Sure thing Bill. I already disassembled the speaker, and am reworking the baffles. I think the next assembly will go smoother and I plan to take and post more pics. The only glue used was contact cement to stick the veneer to the 1/4 rubber plank then I used 2 mm PVC sheet 4 mm foam rubber and another PVC sheet. Kind of a constrained layer approach. Or a sandwich of flexible materials with different acoustic properties. I now plan to glue some new 2 ply cherry veneer directly to the outermost PVC sheet. Same number of layers, same overall thickness, just a different order.
I was referring to my project and how it should sound as good or better would be better. But I have some skepticism about the top position of the low frequency terminus and how it will couple to the room. No boundary gain from the floor. I have been thinking about an upward firing terminus lately, and my wife, because she is out of town, and I miss her pretty face.
I know that there is some disagreement about this, but according to what is known as the "Allison effect", there should be no difference in the average power response at very low frequencies when placing the terminus up high verses placing it down low near the floor. The reason is that the relatively long wavelengths at the very low frequencies are generally longer than the height of the cabinet. According to the "Allison effect", there will be a dip in the average low frequency power response somewhere in the 80 to 300Hz region caused by the spacing distance between the woofer cone and the floor. But the terminus should be unaffected by this dip because the terminus output will be rolling off before reaching 80Hz. One of the quadrants in Jeff Bagby's BDBS program contains the Allison power response equations. You can use this quadrant to enter the terminus height from the floor to see how this affects the power response at various frequencies.
I have reassembled one speaker. However due to considerable difficulty, I need to make some changes in my materials and methods. Also due to leakage between the channels because of the through bolts I cannot test one woofer at a time unless I plug one woofer hole. The impedance with both woofers in parallel shows a triple hump, two tuning frequencies. Omnimic nearfield does not show those tuning frequencies as obvious humps from the terminus or as troughs at the woofers. The crossover needs to be reworked and the frequency lowered, also I need to seal up some minor air leaks. The overall tuning is a bit too low I think, but it sounds very good and extended. I am not sure if I will ever due a pentapath again due to its complexity, but this version one might end up to be a happy accident. I will post my Omnimic results soon that shows a perplexing terminus output down to 20 Hz before it starts to roll off, not at F10, however at a reduced amplitude, a result from the high taper ratio.
I have many tools, but I have never heard of that one, Bill. I have a better place in my room to measure. Farther off of the floor would help too. I just decided to post these preliminary results because they were surprising to me.
Sorry, I meant to say that I think I can get a pretty good combined response in a certain spot in my room. My room is very much dominated by absorption, It has no drywall or paneling on walls or ceiling, only fabrics covering 7-8 inches of fiberglass. Sounds good. Even my wife sounds good in there when she is asking me lots of questions about why I have this or that.
Tweeter 5 feet off the floor and near the better wall, however I still have much to do. My speakers might still be off gassing lacquer fumes in Ft. Wayne.
I should have know better. I will do over without the formica. I have a piece of phenolic backed walnut veneer that I can use. It wont match the cherry but what the heck. Maybe it'll start a new fad.
The side panels are 4/4 local cherry glued up butcherblock style. I originally used a minwax gel stain, not a great product. I shaded the edges with a toner made by adding a small amount of very dark, almost black stain to Sher Wil T76F6 Vinyl sealer, a lacquer based product, spray only. I then decided to shade around the counterbores and didn't like the result. So I sanded it all off with a DA sander but left some of the pigment in the pores. I then restained with a light stain, Sher Wil BAC solvent based stain, vinyl sealer and high build lacquer top coat, another spray only product. That is why the edges are dark. I don't think it looks too bad and adds some interest. It also gives me a reason to talk about woodworking with people.
Comments
Nice cabinet. Looks very professional. The work of a true craftsman. Any chance we can see some detailed construction pics of the internal panel bending and glue up process? I'm just trying to fit all the pieces together in my mind.
Sure thing Bill. I already disassembled the speaker, and am reworking the baffles. I think the next assembly will go smoother and I plan to take and post more pics. The only glue used was contact cement to stick the veneer to the 1/4 rubber plank then I used 2 mm PVC sheet 4 mm foam rubber and another PVC sheet. Kind of a constrained layer approach. Or a sandwich of flexible materials with different acoustic properties. I now plan to glue some new 2 ply cherry veneer directly to the outermost PVC sheet. Same number of layers, same overall thickness, just a different order.
My entry looks so pathetic
It has to sound good too or it will be just form over function.
I was referring to my project and how it should sound as good or better would be better. But I have some skepticism about the top position of the low frequency terminus and how it will couple to the room. No boundary gain from the floor. I have been thinking about an upward firing terminus lately, and my wife, because she is out of town, and I miss her pretty face.
I know that there is some disagreement about this, but according to what is known as the "Allison effect", there should be no difference in the average power response at very low frequencies when placing the terminus up high verses placing it down low near the floor. The reason is that the relatively long wavelengths at the very low frequencies are generally longer than the height of the cabinet. According to the "Allison effect", there will be a dip in the average low frequency power response somewhere in the 80 to 300Hz region caused by the spacing distance between the woofer cone and the floor. But the terminus should be unaffected by this dip because the terminus output will be rolling off before reaching 80Hz. One of the quadrants in Jeff Bagby's BDBS program contains the Allison power response equations. You can use this quadrant to enter the terminus height from the floor to see how this affects the power response at various frequencies.
Those are stunning!
I have reassembled one speaker. However due to considerable difficulty, I need to make some changes in my materials and methods. Also due to leakage between the channels because of the through bolts I cannot test one woofer at a time unless I plug one woofer hole. The impedance with both woofers in parallel shows a triple hump, two tuning frequencies. Omnimic nearfield does not show those tuning frequencies as obvious humps from the terminus or as troughs at the woofers. The crossover needs to be reworked and the frequency lowered, also I need to seal up some minor air leaks. The overall tuning is a bit too low I think, but it sounds very good and extended. I am not sure if I will ever due a pentapath again due to its complexity, but this version one might end up to be a happy accident. I will post my Omnimic results soon that shows a perplexing terminus output down to 20 Hz before it starts to roll off, not at F10, however at a reduced amplitude, a result from the high taper ratio.
Nearfield, upper and lower woofers and terminus
Those individual NF graphs look pretty good to me. Have you tried combining them with a merger tool?
I have many tools, but I have never heard of that one, Bill. I have a better place in my room to measure. Farther off of the floor would help too. I just decided to post these preliminary results because they were surprising to me.
Sorry, I meant to say that I think I can get a pretty good combined response in a certain spot in my room. My room is very much dominated by absorption, It has no drywall or paneling on walls or ceiling, only fabrics covering 7-8 inches of fiberglass. Sounds good. Even my wife sounds good in there when she is asking me lots of questions about why I have this or that.
Tweeter 5 feet off the floor and near the better wall, however I still have much to do. My speakers might still be off gassing lacquer fumes in Ft. Wayne.
New speaker grills.
Wow! Impressive craftsmanship.
Well, that didnt work.
Damn! Bummer!!
Just for the egghead - WTF = Wow, That's Fractured!
I should have know better. I will do over without the formica. I have a piece of phenolic backed walnut veneer that I can use. It wont match the cherry but what the heck. Maybe it'll start a new fad.
Took a vacation day yesterday
Artistry - Do you ever make simple things?
I need to come up with a solution to finish off the terminus,
then finalize the crossovers and tuck them away in the center cavity.
I plan on making drawers today. Pays better than speakers, like not a negative number.
I'm guessing the sides are the cherry? What stain did you use?
The side panels are 4/4 local cherry glued up butcherblock style. I originally used a minwax gel stain, not a great product. I shaded the edges with a toner made by adding a small amount of very dark, almost black stain to Sher Wil T76F6 Vinyl sealer, a lacquer based product, spray only. I then decided to shade around the counterbores and didn't like the result. So I sanded it all off with a DA sander but left some of the pigment in the pores. I then restained with a light stain, Sher Wil BAC solvent based stain, vinyl sealer and high build lacquer top coat, another spray only product. That is why the edges are dark. I don't think it looks too bad and adds some interest. It also gives me a reason to talk about woodworking with people.
Nice!
All buttoned up.
fantastic build