Hi everyone, my first post.
But I have been lurking for a few months.
I am a born again audiophile. I was really into my stereo between 10 and 25 years ago but lost interest, this is obvious by me still using my BSR - RTA Equalizer from the '80's.(Remember DAK?) Oh.. and a DBX-120A...Doh
.
Now I am building it up again.
So, I have 2 - 3.1 ft.^3 cabinets with Pyle (of crap) 15's in them now but I want to change them to a pair of 12's.
I bought some Infinity 1262w's (I know, should have got lab 12's or something) but I am going to use them for now.
I have done many simulations with:
Subwoofer Design Toolbox
A J Vented designer 2.0
WinISD
I am just learning Hornresponse V29.10 and struggling with Akabak (major learning curve)
.
My first question, if I choose to go BR, the port will only fit in one direction (up-down) without using an elbow.
I was thinking of running the ports out the bottom and sitting the speakers up off the floor. Is this a good idea at all?
.
If so, how far do I need to elevate the speakers?
.
I bought 3 -4" port kits from PE with the flanged bell, so I could use the tube and coupler from the third kit to make the ports a few inches longer than the 17" that the kits come with.(Sub toolbox and AJ vented seem to want about 22" (~21 Hz Fb)).
.
I still have my 30 year old copy of Radio Schmucks "Building Speaker Enclosures" and saw a picture of a box vented through the bottom with the standoffs holding up the speaker forming a sort of horn shape starting at the port and expanding at 30 degrees included angle to the front of the speaker. I would use 2 X 4's standing up 3-1/2"
This would fit into my set up well, but would it work well at all?
.
Last question, if I did go BR, what frequency would I need on the high pass filter to prevent over excursion of the speaker?
I assume right at Fb W/24dB per octave, but what do I know.
.
It has relatively long Xmax at 13 mm (+- 6.5) but if I am using Hornresp. correctly it will hit Xmax even at 100W at something near 80 Hz., although I am not sure that I am using Hornrsp. correctly and A J Vented says it hits Xmax at ~ 22 Hz @ 300 watts.
.
Anyway,
I have a Cerwin Vega CV-900 to drive the subs and a Dynaco 80 to drive the mids/tweeters.
I am crossing over with the DBX-120A (120 Hz) right now but may get a DCX2496 so I can do it right. I might even Bi-amp in that case as I also have an old Opamp labs SM-100 servo amp and another set of 2 ft.^3 boxes with 12's in them.
.
The mid/ tweeter box is ~0.9 ft.^3 and each contains 4, 5-1/4" MCM 15-1595 speakers (they called them "Bullfrog Monitor replacement's" way back then")
Also it has 5 el-cheapo Peizo tweeters in each channel.
.
Obviously I will be building all new speaker boxes in the future (maybe even a PPSL) but I need to get by with what I have right now for the time being.
.
I also just bought a Behringer DEQ 2496 with the recommended microphone.
I replaced my 30 year old Peavy mixer with a NOS Tascam M106 (yea EBAY) and also bought a Yamaha MV-802 mixer (no EQ at all) so I can handle all of the inputs I need which are:
Satellite TV
DVD player
Ipod
MC-303 groovebox
Korg Poly 61M synth
Ensonic ESQ-1 synth
All of which are stereo so require 2 channels each.
.
So Hello, hope I bombarded you with enough info to answer my questions.
I look forward to participating on this forum.
Oh, I am a lab tech at a heat engine research lab and also a machinist (Tool&die).
I presently set up test cells and instrument Stirling cycle heat engines, using Labview to collect data.
I also perform all the tests and make many of the modifications on the hardware in our fairly complete machine shop.
I guess you could say I am "handy"
well, Thank you in advance
ShadyDave
PS I may not be back to my computer until Monday, so be patient.
But I have been lurking for a few months.
I am a born again audiophile. I was really into my stereo between 10 and 25 years ago but lost interest, this is obvious by me still using my BSR - RTA Equalizer from the '80's.(Remember DAK?) Oh.. and a DBX-120A...Doh
.
Now I am building it up again.
So, I have 2 - 3.1 ft.^3 cabinets with Pyle (of crap) 15's in them now but I want to change them to a pair of 12's.
I bought some Infinity 1262w's (I know, should have got lab 12's or something) but I am going to use them for now.
I have done many simulations with:
Subwoofer Design Toolbox
A J Vented designer 2.0
WinISD
I am just learning Hornresponse V29.10 and struggling with Akabak (major learning curve)
.
My first question, if I choose to go BR, the port will only fit in one direction (up-down) without using an elbow.
I was thinking of running the ports out the bottom and sitting the speakers up off the floor. Is this a good idea at all?
.
If so, how far do I need to elevate the speakers?
.
I bought 3 -4" port kits from PE with the flanged bell, so I could use the tube and coupler from the third kit to make the ports a few inches longer than the 17" that the kits come with.(Sub toolbox and AJ vented seem to want about 22" (~21 Hz Fb)).
.
I still have my 30 year old copy of Radio Schmucks "Building Speaker Enclosures" and saw a picture of a box vented through the bottom with the standoffs holding up the speaker forming a sort of horn shape starting at the port and expanding at 30 degrees included angle to the front of the speaker. I would use 2 X 4's standing up 3-1/2"
This would fit into my set up well, but would it work well at all?
.
Last question, if I did go BR, what frequency would I need on the high pass filter to prevent over excursion of the speaker?
I assume right at Fb W/24dB per octave, but what do I know.
.
It has relatively long Xmax at 13 mm (+- 6.5) but if I am using Hornresp. correctly it will hit Xmax even at 100W at something near 80 Hz., although I am not sure that I am using Hornrsp. correctly and A J Vented says it hits Xmax at ~ 22 Hz @ 300 watts.
.
Anyway,
I have a Cerwin Vega CV-900 to drive the subs and a Dynaco 80 to drive the mids/tweeters.
I am crossing over with the DBX-120A (120 Hz) right now but may get a DCX2496 so I can do it right. I might even Bi-amp in that case as I also have an old Opamp labs SM-100 servo amp and another set of 2 ft.^3 boxes with 12's in them.
.
The mid/ tweeter box is ~0.9 ft.^3 and each contains 4, 5-1/4" MCM 15-1595 speakers (they called them "Bullfrog Monitor replacement's" way back then
")Also it has 5 el-cheapo Peizo tweeters in each channel.
.
Obviously I will be building all new speaker boxes in the future (maybe even a PPSL
) but I need to get by with what I have right now for the time being..
I also just bought a Behringer DEQ 2496 with the recommended microphone.
I replaced my 30 year old Peavy mixer with a NOS Tascam M106 (yea EBAY) and also bought a Yamaha MV-802 mixer (no EQ at all) so I can handle all of the inputs I need which are:
Satellite TV
DVD player
Ipod
MC-303 groovebox
Korg Poly 61M synth
Ensonic ESQ-1 synth
All of which are stereo so require 2 channels each.
.
So Hello, hope I bombarded you with enough info to answer my questions.
I look forward to participating on this forum.
Oh, I am a lab tech at a heat engine research lab and also a machinist (Tool&die).
I presently set up test cells and instrument Stirling cycle heat engines, using Labview to collect data.
I also perform all the tests and make many of the modifications on the hardware in our fairly complete machine shop.
I guess you could say I am "handy"
well, Thank you in advance
ShadyDave
PS I may not be back to my computer until Monday, so be patient.
Dave,I was thinking of running the ports out the bottom and sitting the speakers up off the floor. Is this a good idea at all?
.
If so, how far do I need to elevate the speakers?
.
I still have my 30 year old copy of Radio Schmucks "Building Speaker Enclosures" and saw a picture of a box vented through the bottom with the standoffs holding up the speaker forming a sort of horn shape starting at the port and expanding at 30 degrees included angle to the front of the speaker. I would use 2 X 4's standing up 3-1/2"
This would fit into my set up well, but would it work well at all?
.
Last question, if I did go BR, what frequency would I need on the high pass filter to prevent over excursion of the speaker?
I assume right at Fb W/24dB per octave, but what do I know.
.
It has relatively long Xmax at 13 mm (+- 6.5) but if I am using Hornresp. correctly it will hit Xmax even at 100W at something near 80 Hz., although I am not sure that I am using Hornrsp. correctly and A J Vented says it hits Xmax at ~ 22 Hz @ 300 watts.
ShadyDave
Downfiring ports work well, if too close to the floor the floor boundary will become part of the port, lowering Fb.
Special port shapes can be effective, but generally require testing to see if the Fb is as planned as they don't fit the typical circular duct most programs model.
A 24 dB per octave high pass filters should be a few Hz lower than the Fb.
Xmax is a one way figure, an Xmax of 13 mm is 26mm peak to peak.
Fb can be verified by putting a white dot on the cone and doing a frequency sweep, excursion will be at minimum at Fb.
Art
Elbows are not totally evil. Also, a flared port can be a tad shorter.
Linkwitz also has a spreadsheet that helped with understanding x-max.
I will tell you this, anywhere near half that the distortion goes through the roof.
How do those drivers model in a low Q sealed box? I find the room gain compensates just about right for sealed boxes. ( I run a pair of Peerless 12's in 60L sealed boxes). You don't want a sub that models flat down to whatever silly low number, like 20, in a room. You actually want it to roll off much earlier. Sealed rolls off at half the slope. Just about right to get the end result in balance.
Linkwitz also has a spreadsheet that helped with understanding x-max.
I will tell you this, anywhere near half that the distortion goes through the roof.
How do those drivers model in a low Q sealed box? I find the room gain compensates just about right for sealed boxes. ( I run a pair of Peerless 12's in 60L sealed boxes). You don't want a sub that models flat down to whatever silly low number, like 20, in a room. You actually want it to roll off much earlier. Sealed rolls off at half the slope. Just about right to get the end result in balance.
Discovered yet another good sim program
Thank you for the replies.
I have been doing all my modeling at work during lunchtime, as I have no internet connection at home.
I finally took my thumb drive home with all my speaker specs and sim programs, and I found another program on my thumb drive that I have not used yet.
Woofer Box Model and Circuit designer 4.5
I like it as I can put the crossovers and even an LR filter in it, and it is very intuitive to learn (I am very partial to .xls simulations because I have written so many myself).
.
I spent many hours with that yesterday and I have decided to go with a sealed box.
There seems to be much better control of cone excursion and I have read that SQ is much better with a sealed box, unless you have a very good BR design. Also I found that 2 sim programs tell me I need a 6" diameter port.
.
What would you consider a "Low Q" sealed box value?
My box volume gives a Qtc of 0.669
.
At 300 Wrms and with just a 22 Hz 4 pole high-pass filter and a 100 Hz (LR) low pass I can get 100 dB @ 25Hz without exceeding Xmax and peak output of 110 dB @ 70 Hz per speaker. So I guess 103 dB and 113 dB with the pair.
But is this at 1 Meter?
I may find out when I do the room response file.
No decent help file for Woofer Box and Circuit Model
.
I still need to input the room parameters, I am sure that I will get significant gain from them.
.
This is good enough for now, and is only temporary.
Seems I've got the bug and will have to build some good speaker cabs W/good drivers.
.
.
Well I did some research and found:
AJ Sealed (and Ported) designer V2.0 the Xmax is input as amplitude, not peak to peak.
.
I found a reference on DIY Audio and Video dot com that says Winisd wants amplitude in the DriverEditor file.
Quote "Maximum peak linear excursion".
.
I have not figured out what AKAbak wants, but I have a long way to go before I will be competent with that program.
It reminds me of PSpice and I assume it is a powerful tool.
.
I can not find out what Woofer Box Model and Circuit designer 4.5 wants (Peak or Pk. to Pk) No help file
.
I have one other question for anyone who uses simulations.
When I input speaker diameter, should that be based on the radiating area?
I am assuming that I do not input 30.5 cm for a 12" speaker.
The radiating area on the 1262W converts to a diameter of 26.0 cm.
I thank all for your help.
Dave
Thank you for the replies.
tvrgeek said:
I have been doing all my modeling at work during lunchtime, as I have no internet connection at home.
I finally took my thumb drive home with all my speaker specs and sim programs, and I found another program on my thumb drive that I have not used yet.
Woofer Box Model and Circuit designer 4.5
I like it as I can put the crossovers and even an LR filter in it, and it is very intuitive to learn (I am very partial to .xls simulations because I have written so many myself).
.
I spent many hours with that yesterday and I have decided to go with a sealed box.
There seems to be much better control of cone excursion and I have read that SQ is much better with a sealed box, unless you have a very good BR design. Also I found that 2 sim programs tell me I need a 6" diameter port.
.
What would you consider a "Low Q" sealed box value?
My box volume gives a Qtc of 0.669
.
At 300 Wrms and with just a 22 Hz 4 pole high-pass filter and a 100 Hz (LR) low pass I can get 100 dB @ 25Hz without exceeding Xmax and peak output of 110 dB @ 70 Hz per speaker. So I guess 103 dB and 113 dB with the pair.
But is this at 1 Meter?
I may find out when I do the room response file.
No decent help file for Woofer Box and Circuit Model
.
I still need to input the room parameters, I am sure that I will get significant gain from them.
.
This is good enough for now, and is only temporary.
Seems I've got the bug and will have to build some good speaker cabs W/good drivers.
.
Does this mean that I should input 26 mm as Xmax?weltersys said:
.
Well I did some research and found:
AJ Sealed (and Ported) designer V2.0 the Xmax is input as amplitude, not peak to peak.
.
I found a reference on DIY Audio and Video dot com that says Winisd wants amplitude in the DriverEditor file.
Quote "Maximum peak linear excursion".
.
I have not figured out what AKAbak wants, but I have a long way to go before I will be competent with that program.
It reminds me of PSpice and I assume it is a powerful tool.
.
I can not find out what Woofer Box Model and Circuit designer 4.5 wants (Peak or Pk. to Pk) No help file
.
I have one other question for anyone who uses simulations.
When I input speaker diameter, should that be based on the radiating area?
I am assuming that I do not input 30.5 cm for a 12" speaker.
The radiating area on the 1262W converts to a diameter of 26.0 cm.
I thank all for your help.
Dave
Hi,
The Radiation Area(Sd) or the Radiation Diameter are correct to use in simulation programs.
b
.
At 300 Wrms and with just a 22 Hz 4 pole high-pass filter and a 100 Hz (LR) low pass I can get 100 dB @ 25Hz without exceeding Xmax and peak output of 110 dB @ 70 Hz per speaker. So I guess 103 dB and 113 dB with the pair.
But is this at 1 Meter?
I may find out when I do the room response file.
No decent help file for Woofer Box and Circuit Model
.
I still need to input the room parameters, I am sure that I will get significant gain from them.
.
I wouldn't count on the peak SPL rating you've given: while they will mechanically put out 110dB at 70Hz, if any lower frequencies were present, you'd hear the sound of different parts of the speaker bouncing off each other.
If you take the high pass to 40Hz (sufficient for probably 90% of music), you'll gain significant SPL capability at the expense of some bass extension. This is something you could experiment with to find the balance that's right for you.
Room gain and wall/corner loading will provide considerable boost to the LF: winISD models a speaker in half-space (ie, in a field). IIRC, you gain 3dB by putting the speaker up against a wall (quarter space), and another 3dB by putting the speaker in a corner (eighth space).
The above figures rely on the walls being perfectly rigid, so that all the LF energy is directed into the room.
Put simply, room gain is complicated business and several members here have used many subwoofers placed strategically around the room to iron out the room's effects on the low stuff. Most of us make do with the more pedestrian approach of repeatedly moving the sub around the room until the best sound is found.
Chris
If your speaker is listed for 26 mm Xmax, use 26, if it is listed as 13 mm Xmax, use 13.
As I mentioned previously, Fb can be verified by putting a white dot on the cone and doing a frequency sweep, excursion will be at minimum at Fb in a ported box, it increases rapidly above and below Fb.
When you measure excursion by eye using a ruler you will be reading peak to peak, so divide that figure by 2 to see how close you are to Xmax.
A speaker in a sealed box just steadily increases in excursion, dropping in output as frequency decreases.
Reflective room
I did not realize how much gain you can get from the Room response.
I made a room model with the "Baffle Edge Diffraction & Room Response Reinforcement" model that goes along with the Woofer Box and Circuit Designer.
It shows 8.3 dB gain at 70 Hz and 10.7 dB gain at 30 Hz.
.
I need to get a good model going on winISD as I would think it is a more accurate model.
.
I also know that I am going to have to invest in some corner absorbers and a few wall mounted absorbers as the room is 16' X 22' with 12" concrete block walls.
.
I just received the Behringer DCX 2496 and plan on playing around with filtering quite a bit, including LR highpass filters.
.
Thanks for all the help, I will update as I run into problems and also try to figure out how to post a few pictures.
Dave
I did not realize how much gain you can get from the Room response.
I made a room model with the "Baffle Edge Diffraction & Room Response Reinforcement" model that goes along with the Woofer Box and Circuit Designer.
It shows 8.3 dB gain at 70 Hz and 10.7 dB gain at 30 Hz.
.
I need to get a good model going on winISD as I would think it is a more accurate model.
.
I also know that I am going to have to invest in some corner absorbers and a few wall mounted absorbers as the room is 16' X 22' with 12" concrete block walls.
.
I just received the Behringer DCX 2496 and plan on playing around with filtering quite a bit, including LR highpass filters.
.
Thanks for all the help, I will update as I run into problems and also try to figure out how to post a few pictures.
Dave
Hrsp file
tb46,
Thanks for that example.
I had almost the same simulation, but I did not know how to put ports into the sim.
My sim. had Fr and Tal, so only a sealed box.
When I saw your example and it had the port area and length, I spent some time in the menus until I figured out how to change that.
And then, I was getting weird results until I found where you set the port at the same plane as the driver.
Now it looks like your file, and results.
A few of my numbers were a little different, and I already have cabinets, so the volume is fixed.
This file shows the existing cabinet volume minus the speaker (4.1 L) and the port volume for a 24 Hz port..
This is the input file.
And the output.
At 24.0 Volts (~300 Watts) it gives me 100 dB at 25 Hz, and 112 or 113 dB between 70 and 100 Hz.
That agrees well with the "Woofer Box and Circuit Designer" program.
Anyway, thanks
Dave
tb46,
Thanks for that example.
I had almost the same simulation, but I did not know how to put ports into the sim.
My sim. had Fr and Tal, so only a sealed box.
When I saw your example and it had the port area and length, I spent some time in the menus until I figured out how to change that.
And then, I was getting weird results until I found where you set the port at the same plane as the driver.
Now it looks like your file, and results.
A few of my numbers were a little different, and I already have cabinets, so the volume is fixed.
This file shows the existing cabinet volume minus the speaker (4.1 L) and the port volume for a 24 Hz port..
This is the input file.
And the output.
At 24.0 Volts (~300 Watts) it gives me 100 dB at 25 Hz, and 112 or 113 dB between 70 and 100 Hz.
That agrees well with the "Woofer Box and Circuit Designer" program.
Anyway, thanks
Dave
Bottom Firing Port
I was wondering if anyone saw any major problems with my approach in making a floor firing port on a BR enclosure.
I had decided on making a sealed box but if I port the box it seems to have much better control over driver amplitude when close to Fb.
The boxes already exist and I am going to use 3/4" and 1/2" BB Ply glued together for the front panel, and also use the outside of the panel as a mount for a 1 x 3 frame with grill cloth stretched over it.
I will use both low pass and high pass filters (DCX 2496), but if the high pass filter stops working a sealed box has extreme over excursions.
Anyway, I was planning on making a base from 2 X 4 lumber so the port would have a 3-1/2" space between it's outlet and the floor.
Is this enough, or should I use 2 X 6 lumber (5-1/2").
It is a flared 4" port kit.
I was also a little concerned with the internal port flare ending up so close to the driver, I am not sure if that is an issue.
Any and all comments welcome.
A picture tells a........
Thanks, Dave
I was wondering if anyone saw any major problems with my approach in making a floor firing port on a BR enclosure.
I had decided on making a sealed box but if I port the box it seems to have much better control over driver amplitude when close to Fb.
The boxes already exist and I am going to use 3/4" and 1/2" BB Ply glued together for the front panel, and also use the outside of the panel as a mount for a 1 x 3 frame with grill cloth stretched over it.
I will use both low pass and high pass filters (DCX 2496), but if the high pass filter stops working a sealed box has extreme over excursions.
Anyway, I was planning on making a base from 2 X 4 lumber so the port would have a 3-1/2" space between it's outlet and the floor.
Is this enough, or should I use 2 X 6 lumber (5-1/2").
It is a flared 4" port kit.
I was also a little concerned with the internal port flare ending up so close to the driver, I am not sure if that is an issue.
Any and all comments welcome.
A picture tells a........
Thanks, Dave
Down Firing Ports
Didn't think I would like it, until I tried it - my subs never sounded better.
http://www.diyaudio.com/forums/subwoofers/203345-isobaric-less-then-20-a-31.html
post # 307 and 343.
Didn't think I would like it, until I tried it - my subs never sounded better.
http://www.diyaudio.com/forums/subwoofers/203345-isobaric-less-then-20-a-31.html
post # 307 and 343.
Hi Shadydave,
Post #12: "...a little concerned with the internal port flare ending up so close to the driver..."
It most likely will not be a problem, but maybe you can lower the driver a few inches to be on the safe side.
As to the ground clearance - assuming that the hatched, green pieces in the top view are the 2x4 pieces for the base - that looks fine (maybe a little overkill); you may be able to optimize the transition from tubular duct to 2x4 duct, and shave a bit of length of the tube. The last time I used a similar port was in a set of experiments with sonotubes; it worked just fine with a BR and a BP4. The ports worked just as predicted.
Regards,
Post #12: "...a little concerned with the internal port flare ending up so close to the driver..."
It most likely will not be a problem, but maybe you can lower the driver a few inches to be on the safe side.
As to the ground clearance - assuming that the hatched, green pieces in the top view are the 2x4 pieces for the base - that looks fine (maybe a little overkill); you may be able to optimize the transition from tubular duct to 2x4 duct, and shave a bit of length of the tube. The last time I used a similar port was in a set of experiments with sonotubes; it worked just fine with a BR and a BP4. The ports worked just as predicted.
Regards,
In over my head...DOH..Newbie questions
This all started because a recent room mates cat sharpened her claws (the cat, not the room mate, I think) on the surrounds in my 3 ft.^3 boxes with old Pyle (15-400 I think) 15" drivers.
So I bought a set of Infinity 1262W woofers, then I found this forum and started to learn.
I still planned on using the boxes with the Infinity 12's for now, quick and dirty.
.
Well I removed the 3/4 ply baffle that was tacked onto the front of the boxes original baffles and found that the 30 year old particle board boxes are in worse shape than the surrounds on the speakers.
.
So, being in a hurry and working way too many hours right now I purchased a set of Knock down boxes from Parts Express.
These PA Knock-Down Trapezoid Birch Speaker Cabinet for 15" Driver 245-326
.
They are meant for 15's but I have 4 sheets of quality Baltic Birch that I was going to double baffle the old boxes with, so I will do the same.
Center the 12" woofer in the 14" cutout using another piece of 3/4" Baltic Birch.
.
I have several questions.
Should I use PL-400 or Titebond to glue up the cabinets?
.
If I need to fill small voids can I use waterputty?
.
I bought 4-4' sections of 1" diameter Oak dowel rod for bracing.
This should give me 3 or 4 braces in each box.
If I get one long #10 wood screw right in the middle of a tight fitting brace and also glue it, is that adequate?
Or should I add some 4" square end plates like one would use on a roll cage in a car, made from ply of course. (my wood welder is broken).
.
I am going to start with a sealed box, I can always port it later.
I have some egg crate foam sheets and was going to spray glue that to at least 3 walls.
I also have 3-1 lb. bags of Acousta-stuf Polyfill and was going to follow the directions of 1/2 lb. / ft.^3, or 1-1/2 lbs. per box.
Does this sound about right?
.
I would like to finish them with some sort of black very textured paint.
There is some pretty good stuff in spray cans but I would probably need allot of cans.
Any ideas what I could buy in gallon sizes for black texture finish?
.
The boxes are ~ 2-3/4 ft.^3 and seem to be just about right.
A Qtc of 0.707 needs 70 Liters and these will be 73 Liters after subtracting the speaker volume.
.
For some reason Photobucket does not seem to want to work, so a few hundred words sort of describe a picture, sort of.
And according to Jeff Bagby's Woofer Box and circuit designer 4.5 they will be 100 dB each at 30 Hz and if I add the Room Boundary Simulator they will be about 100 dB at 20 Hz and reach 113 dB by 40 Hz and 115 dB by 100 Hz.
This is at 300 watts, and although the amp is capable of 420 watts I would not be turning it up that high, so that is just headroom.
My old Radio Shack SPL meter tells me that I consider 80 dBA to be loud.
That is plenty for me, and that is using the 2nd order 40 Hz high pass in the Cerwin-Vega amps which should limit Xmax to 7.1 out of 13.0 mm.
Hornresp seems to agree fairly closely but I can not simulate the high pass filter to that to keep the Xmax down (or I don't know how).
.
Eventually I want to build a 15 or 18" PPSL and will relegate these to be mid basses, but for now at least I can have some sound.
Thank you for all your wisdom and patience.
Dave
This all started because a recent room mates cat sharpened her claws (the cat, not the room mate, I think) on the surrounds in my 3 ft.^3 boxes with old Pyle (15-400 I think) 15" drivers.
So I bought a set of Infinity 1262W woofers, then I found this forum and started to learn.
I still planned on using the boxes with the Infinity 12's for now, quick and dirty.
.
Well I removed the 3/4 ply baffle that was tacked onto the front of the boxes original baffles and found that the 30 year old particle board boxes are in worse shape than the surrounds on the speakers.
.
So, being in a hurry and working way too many hours right now I purchased a set of Knock down boxes from Parts Express.
These PA Knock-Down Trapezoid Birch Speaker Cabinet for 15" Driver 245-326
.
They are meant for 15's but I have 4 sheets of quality Baltic Birch that I was going to double baffle the old boxes with, so I will do the same.
Center the 12" woofer in the 14" cutout using another piece of 3/4" Baltic Birch.
.
I have several questions.
Should I use PL-400 or Titebond to glue up the cabinets?
.
If I need to fill small voids can I use waterputty?
.
I bought 4-4' sections of 1" diameter Oak dowel rod for bracing.
This should give me 3 or 4 braces in each box.
If I get one long #10 wood screw right in the middle of a tight fitting brace and also glue it, is that adequate?
Or should I add some 4" square end plates like one would use on a roll cage in a car, made from ply of course. (my wood welder is broken).
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I am going to start with a sealed box, I can always port it later.
I have some egg crate foam sheets and was going to spray glue that to at least 3 walls.
I also have 3-1 lb. bags of Acousta-stuf Polyfill and was going to follow the directions of 1/2 lb. / ft.^3, or 1-1/2 lbs. per box.
Does this sound about right?
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I would like to finish them with some sort of black very textured paint.
There is some pretty good stuff in spray cans but I would probably need allot of cans.
Any ideas what I could buy in gallon sizes for black texture finish?
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The boxes are ~ 2-3/4 ft.^3 and seem to be just about right.
A Qtc of 0.707 needs 70 Liters and these will be 73 Liters after subtracting the speaker volume.
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For some reason Photobucket does not seem to want to work, so a few hundred words sort of describe a picture, sort of.
And according to Jeff Bagby's Woofer Box and circuit designer 4.5 they will be 100 dB each at 30 Hz and if I add the Room Boundary Simulator they will be about 100 dB at 20 Hz and reach 113 dB by 40 Hz and 115 dB by 100 Hz.
This is at 300 watts, and although the amp is capable of 420 watts I would not be turning it up that high, so that is just headroom.
My old Radio Shack SPL meter tells me that I consider 80 dBA to be loud.
That is plenty for me, and that is using the 2nd order 40 Hz high pass in the Cerwin-Vega amps which should limit Xmax to 7.1 out of 13.0 mm.
Hornresp seems to agree fairly closely but I can not simulate the high pass filter to that to keep the Xmax down (or I don't know how).
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Eventually I want to build a 15 or 18" PPSL and will relegate these to be mid basses, but for now at least I can have some sound.
Thank you for all your wisdom and patience.
Dave
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