i plan to make a rough n ready tube tl, a la linkwitz designs. The tube is 1.2m long 47 inch, and 3 inch ID. i get a tuning of around 70hz. Now being as it isnt going to be optimal, according to MJK tables due to qts and vas, and the tube CSA likely too small, what effect on response should i expect? Im imagining that with a smaller than ideal CSA, that a humped response around resonance would occur. Am i right in thinking this?
What driver do you plan to use, some cheap 3" TB or Aura?
FWIW, the Zu Druid had a tiny CSA for its 10" driver, maybe the latter's parameters do want a small CSA, but it looks barely larger than Sd. I've never heard this speaker, just noticed this characteristic.
I once made a 4" I.D. ABS pipe line for some 4" JVC drivers, IIRC tuned close to their Fs of ~110Hz. Qts was high on these, ~0.7. It didn't do too well in my case.
IG
FWIW, the Zu Druid had a tiny CSA for its 10" driver, maybe the latter's parameters do want a small CSA, but it looks barely larger than Sd. I've never heard this speaker, just noticed this characteristic.
I once made a 4" I.D. ABS pipe line for some 4" JVC drivers, IIRC tuned close to their Fs of ~110Hz. Qts was high on these, ~0.7. It didn't do too well in my case.
IG
i have mini experiments planned for alpair5 grey, and tb w3-1285sg, so the el cheapo is only regarding the card tube! They both have radically different values of qts, and probably vas also, i cant recall at present. I would imagine that the higher qts of the A5 would choke up the bass, as i think the driver requires a greater pipe CSA, or volume behind the driver.
@scott i appreciate that feeling, hectic doesnt seem strong enough to describe my life right now, a week to go til my OH reaches her due date...lol
@scott i appreciate that feeling, hectic doesnt seem strong enough to describe my life right now, a week to go til my OH reaches her due date...lol
Last edited:
if you thought things were hectic before the due date, this must be your first?
haha thanks guys. Yes hes my first, born yesterdaybut im already busy with part time degree and full time work, and about 4 speaker projects on the go. Beats having too much time on my hands though!
congrats - each completed project adds 2 more to the "to do list"
Firstly, Thanks all for the kind words. And now speakers again!
Well I got my card tubes back home today!
They are 1.2m long by 3" ID, walls about 15mm thick perhaps.
The way I figure, the pipe resonance occurs at:
{(1.2/342)/4}^-1 = ~71 hz
the Fs of the W3-1285SG is quoted as 100 Hz, I figured a longer tube may compensate a little for the CSA of the pipe being 7 sq.inch, but probably not enough for the A5
The Tangbands were sealed into the end of the tube, using plasticine.
Very ringy, pipe like sound.....strangly.....haha
filling lightly with some rolled up 1/2" PU foam, and a little felt took the vast majority away.
so basically what I have is a horizontal 4ft long pipe with a driver in it, 'Bazooka' perhaps?....
*Since the bass rear wave is displaced 4 ft behind the front radiating surface, the sound varies alot around the 'side' of the speaker*, and the bass output from the open end is really very surprising, not as clean as a larger speaker, but most definitely there. Considering the almost dipole behavior, and all else, im rather pleased in what sound is produced by these drivers.
I was also going to try the Alpair 5s but the supporting members of the driver chassis are a fraction wider than the internal diameter of the pipe. Perhaps some 'machining' of the card will follow....
I am however, expecting the Alpairs to better the TBs in THD, and ultimatly perhaps general sound quality, BUT, I dont think the tuning will work well with the A5s, since the pipe volume is low.
But thats the next experiment. probably a number of sketches later...
*Aside: Regarding the 4ft front to back vent displacement almost dipole effect....
In a way I think id love to put a shallow fraction of a sphere as a baffle, even better an ellipse, maybe 5x3 ft...if I had the room......good experiment though.*
Well I got my card tubes back home today!
They are 1.2m long by 3" ID, walls about 15mm thick perhaps.
The way I figure, the pipe resonance occurs at:
{(1.2/342)/4}^-1 = ~71 hz
the Fs of the W3-1285SG is quoted as 100 Hz, I figured a longer tube may compensate a little for the CSA of the pipe being 7 sq.inch, but probably not enough for the A5
The Tangbands were sealed into the end of the tube, using plasticine.
Very ringy, pipe like sound.....strangly.....haha
filling lightly with some rolled up 1/2" PU foam, and a little felt took the vast majority away.
so basically what I have is a horizontal 4ft long pipe with a driver in it, 'Bazooka' perhaps?....
*Since the bass rear wave is displaced 4 ft behind the front radiating surface, the sound varies alot around the 'side' of the speaker*, and the bass output from the open end is really very surprising, not as clean as a larger speaker, but most definitely there. Considering the almost dipole behavior, and all else, im rather pleased in what sound is produced by these drivers.
I was also going to try the Alpair 5s but the supporting members of the driver chassis are a fraction wider than the internal diameter of the pipe. Perhaps some 'machining' of the card will follow....
I am however, expecting the Alpairs to better the TBs in THD, and ultimatly perhaps general sound quality, BUT, I dont think the tuning will work well with the A5s, since the pipe volume is low.
But thats the next experiment. probably a number of sketches later...
*Aside: Regarding the 4ft front to back vent displacement almost dipole effect....
In a way I think id love to put a shallow fraction of a sphere as a baffle, even better an ellipse, maybe 5x3 ft...if I had the room......good experiment though.*
Last edited:
I understand the ringyness you speak of.
Im reminded of hollering into storm sewers as a kid and more recntly singing into cardboard tubes from wrapping paper. As i sang up and down a scale some frequencies would bounce right back down my throat and the whole tube would viberate. Pipe resonance yes?
The stuffing you did, i believe, would stop the certain frequencies from doing this and slamming back into the driver.
A question just occured to me, what is the dimension of the stuffing you used, and at what position along the pipe from the driver was it placed?
Perhaps you could find the smallest(shortest) plug and slide it along the tube to eq out the pipe resonance?
Other resonances would travel right through the plug and would require other plugs along the length of the tube?
Im reminded of hollering into storm sewers as a kid and more recntly singing into cardboard tubes from wrapping paper. As i sang up and down a scale some frequencies would bounce right back down my throat and the whole tube would viberate. Pipe resonance yes?
The stuffing you did, i believe, would stop the certain frequencies from doing this and slamming back into the driver.
A question just occured to me, what is the dimension of the stuffing you used, and at what position along the pipe from the driver was it placed?
Perhaps you could find the smallest(shortest) plug and slide it along the tube to eq out the pipe resonance?
Other resonances would travel right through the plug and would require other plugs along the length of the tube?
Haha yes, I was expecting the pipe sound I have to say, but the addition of stuffing did help.
The sound is far from perfect however, but interesting in its nature. using it horizontally, it reminds me of a shotgun mic, hence the 'bazooka' at the start lol.
Im wondering if its behavior, is somehow similar to a shotgun mic, as well, and if that can be used to a home hifi advantage, if you will.
I placed some fairly dense PU foam, in 'sticks' of maybe 1" square by 10" long around 2/3rds the way down the tube, and added a loose roll of felt in the driver end. I had thought that if i could make a cone of foam, then I could use the large end of the cone at the open end of the tube. In this way the area of the tube would be tapered, or maybe not... maybe the foam is almost invisible to the sound.....either way, I could reduce the vent area in this way anyway, and the foam would damp the 2/3rd position still.
The sound is far from perfect however, but interesting in its nature. using it horizontally, it reminds me of a shotgun mic, hence the 'bazooka' at the start lol.
Im wondering if its behavior, is somehow similar to a shotgun mic, as well, and if that can be used to a home hifi advantage, if you will.
I placed some fairly dense PU foam, in 'sticks' of maybe 1" square by 10" long around 2/3rds the way down the tube, and added a loose roll of felt in the driver end. I had thought that if i could make a cone of foam, then I could use the large end of the cone at the open end of the tube. In this way the area of the tube would be tapered, or maybe not... maybe the foam is almost invisible to the sound.....either way, I could reduce the vent area in this way anyway, and the foam would damp the 2/3rd position still.
- Status
- This old topic is closed. If you want to reopen this topic, contact a moderator using the "Report Post" button.