[kryptonitewhite]

I got myself a cardboard tube that has an internal dia of 5.5" and it's 8 feet 6 and 5/8 inches long. I have a cheap walmart surround sound with a 5.25" "sub" that I already modified last summer with a paper towel tube to lower the tune and for fun i added a TP roll tube to the cone for an excursion vid that I decided to leave on for fun and to increase mass....

I'll take the tube off and put this 5.25 in the...TL?

So 8.5' X 2 = 17ft 1/2 wave 66Hz?

8.5' X 4 = 34ft 1/4 wave 33Hz???

 

[Bill Fitzmaurice]

I got myself a cardboard tube that has an internal dia of 5.5" and it's 8 feet 6 and 5/8 inches long. I have a cheap walmart surround sound with a 5.25" "sub" that I already modified last summer with a paper towel tube to lower the tune and for fun i added a TP roll tube to the cone for an excursion vid that I decided to leave on for fun and to increase mass....

I'll take the tube off and put this 5.25 in the...TL?

So 8.5' X 2 = 17ft 1/2 wave 66Hz?

8.5' X 4 = 34ft 1/4 wave 33Hz???

Your figures are correct. Stuff it with polyester pillow stuffing and mount the driver in one end and you're good to go. But don't expect too much from it, extension will be dependant on the driver Fs and Qts, output will be limited by driver Vd, and with any five inch driver, let alone a Walmart variety, those limits will be reached early on.

 

[kryptonitewhite]

Your figures are correct. Stuff it with polyester pillow stuffing and mount the driver in one end and you're good to go. But don't expect too much from it, extension will be dependant on the driver Fs and Qts, output will be limited by driver Vd, and with any five inch driver, let alone a Walmart variety, those limits will be reached early on.

How much stuffing? I think i saw a post from you about them....they are the $5 walmart pillow stuffers?

I don't expect much at all, I'm quite impressed with it's sound when I have the port extension on it... it's one of those small Sd drivers because a good inch is used up for the mounting lip on the basket, more like a 4" on a 5.25" frame... I am very impressed with it's Xmech, the thing really moves, somewhat impressed with Xmax as well... it goes a good distance till suddenly stress is very audible... 2 clicks goes from very clean to very stressed, it's a fine line. I will leave the roll glued to the cone to lower Fs a tad... it may be helping now in it's lower sound. I'll locate my camera and take some pics, I'm in the process of moving and everyhing's burried in boxes.

I figure cheap speaker, free tube, 1st try at a very complex design...expect nothing and be a little surprised

Thanks Bill!

 

[kryptonitewhite]

pardon the move into a ghetto apartment, but it matches the ghettophied sub that I made for myself. you would never guess i was a proud owner of 2 15" Ascendant Audio Avalanches, 4 Extremis, Audio Control 6XS yadda yadda.... But my Kenwood receiver's DSP took a dump years ago, so I have just been running this thing for now...and it has been fun.

I slapped the port back into it, just to show what i had... it was quite functional, lowered from a peak of around 55-65Hz down to 30-40Hz. It suffered port noise at higher volume, but I preferred it at lower volume for lower extention than the high annoyingness when it was tuned much too high. It worked, and it worked well, regardless of how it looked.

So if/when i stuff this thing, it should lower things noticeably, correct?

Thanks again!

 

[kryptonitewhite]

OH MY WOW! I have found my new obsession! going from pre-fab high tuned to modifying myself to lower a bit, to a TL is indescribable!

I have only had 3-4 minutes play, but wow, it's totally there...and I was right on a guess...being at the port side is not as loud as speaker side, as the tuning frequencies are what u hear most, and as u get away from tuning you lose more the further you go, but center pipe is where it is at!

I been thinking the last 2 days where to mount this giant thing in our already cramped room, and 1st I considered "speaker side or port side loaded in corner? port side will have the group delay, so if I put the speaker side in and port facing us { now I know how impossible that is with an 8' pipe in say a 12' room} then group delay shouldn't be too much an effect, and though we lose some high end having the speaker itself further away, but it will load into the corner..."

But then last night I was guessing each end will have a cancellation point, but center pipe would be the coupling...sure is! when you start at 1 end and work to the middle, BOOM! there it is!

 

[Mike P.]

when you start at 1 end and work to the middle, BOOM! there it is!

The speaker should be placed 1/3 of the way into the tube, like the Acoustic Wave® Cannon System

http://www.audiolat.lv/awcs.htm

There is also DIY version

http://www.diyaudio.com/forums/showthread.php?threadid=9501

 

[Bill Fitzmaurice]

So if/when i stuff this thing, it should lower things noticeably, correct?

Not a bit. The stuffing is used to suppress unwanted resonances above the pipe frequency.

group delay shouldn't be too much an effect

Below 100 Hz group delay isn't audible and never has to be considered.

when you start at 1 end and work to the middle, BOOM! there it is!

Resonance an octave up from the pipe frequency is you're hearing, and it seems louder due to Fletcher-Munson effect. The preferred driver mounting is 1/5 from the closed end of the pipe, placing the primary resonance mode above the passband. Bose does it at 1/3 to capitalize on Fletcher-Munson and give the illusion of bass that isn't there.

 

[kryptonitewhite]

The speaker should be placed 1/3 of the way into the tube, like the Acoustic Wave® Cannon System

http://www.audiolat.lv/awcs.htm

There is also DIY version

http://www.diyaudio.com/forums/showthread.php?threadid=9501

I thought Tapered Quarter Wave Pipe and other versions were the 1/3rd, and this was a plain QW?

I have some bad "echo/resonance" I am guessing stuffing will cure?

Got it mounted...very crude and ugly, but I am just playing for now...

 

[kryptonitewhite]

Not a bit. The stuffing is used to suppress unwanted resonances above the pipe frequency.
Below 100 Hz group delay isn't audible and never has to be considered.

Resonance an octave up from the pipe frequency is you're hearing, and it seems louder due to Fletcher-Munson effect. The preferred driver mounting is 1/5 from the closed end of the pipe, placing the primary resonance mode above the passband. Bose does it at 1/3 to capitalize on Fletcher-Munson and give the illusion of bass that isn't there.

Boy do i have some resonance! I was hoping to skip that process, but we be getting pillows! But I am really loving this! If this is what a 4" wanna be a 5.25 speaker can do from walmart....

OK, so if a person tues below 15Hz, no worries? When I was plotting all the time with my 20Hz wall, I was worried about the delay numbers.

So the 1/4 wave effect is pretty much the same no matter where you mount the driver...or should I say, a TL will function no matter where it is, but, the resonances will be increased/reduced depending?

 

[Bill Fitzmaurice]

So the 1/4 wave effect is the same pretty much the same no matter where you mount the driver...or should I say, a TL will function no matter where it is, but, the resonances will be increased/reduced depending?

The primary pipe exit output is centered at the 1/4 wavelength pipe frequency. Anything else is technically undesirable. The driver location and stuffing are used to minimize those unwanted resonances.

 

[kryptonitewhite]

The primary pipe exit output is centered at the 1/4 wavelength pipe frequency. Anything else is technically undesirable. The driver location and stuffing are used to minimize those unwanted resonances.

IC... I think i'll leave it as is, since this is pretty simple for what I have into it, so will stuffing help a little? The resonance is atrocious! So I will keep it in mind if I ever do another... definately doing 1/5th! During a song intro, it is beautiful... but when it's blended, especially thumping, the uppers totally take over

 

[kryptonitewhite]

OK...so for a while I was staring at it, and the GF was wrapping presents...paper was almost out, and I thought, Sonotube. Plug the end and port it with the wrapping paper tube...same diameter as the paper towel tube, but much longer, and much more airspace for the tube, will be super low... miniature LLT lol.

But then... I can get more 5.5" tube... I'm trying to think of the algebra to make 5.6 4/5ths of my total length? Ah i suck at this stuff...

I want to add more pipe to the front of the speaker now so it is 1/5th in from the total length.

 

[SteveCallas]

you would never guess i was a proud owner of 2 15" Ascendant Audio Avalanches

:yay::bigsmile::clap::T:demon::wave:

:blink::sad2::doh::rolleyesno::no::foottap::huh:

 

[kryptonitewhite]

:yay::bigsmile::clap::T:demon::wave:

:blink::sad2::doh::rolleyesno::no::foottap::huh:

hehehe... I was already blushing before that... I guess I couldda dropped some real dough on my 1st experiment gone bad, gotten some 18" concrete tube, say 80 feet, a maelstrom-x, EP2500, yadda yadda.... hehehe

 

[SteveCallas]

No harm intended.

 

[kryptonitewhite]

my upgrade, still happy to incorporate cardboard, duct tape, dangling wires, and a plug in AC cover

edit: and u can see the blue light shadow, with yellow overtones, from my kick $5 energy efficient (green?) coil light!

 

[kryptonitewhite]

http://en.wikipedia.org/wiki/Acoustic_transmission_lines

"typically, extended bass below a half wave frequency of the reflected line length e.g. 30Hz=8 foot length;"

http://www.mcsquared.com/wavelength.htm

according to that calculator, 30Hz is 37.6Hz, /4= 9.4', not 8!