Sub build pictures

[TLS Guy]

The port 4" flared at both ends and 17" long ( I got the length from winISD) and got a Mach of .11 (I am using the midq option)

I see I sent you the low Q alignment previously. These are the dimeansions and prt for the mid Q insert.

Vb = 4.653 cu.ft
Fb = 18.02 Hz
QL = 6.207
F3 = 18.01 Hz
Fill = minimal
No. of Vents = 1
Vent shape = round
Vent ends = two flared
Dv = 4 in
Lv = 20.3 in

What did you make your enclosure volume? For 4.63 cu.ft the four inch vent is 20.3 inches. Vent air speed is 30 m/sec. That is at full power, I seriously doubt you will ever put 400 watts to it!

 

[flippo]

I made my enclosure at 3.5 cubic feet. Any larger and I think my wife would have fainted. I enjoyed making it, it's not perfect but is a good start. I really like it so far, the bass is deep and tight and doesn't have that bloom like my polk sub. It is much more articulate and there is more of a snap to the music. I plan on making a grill for it since I didn't do a very good job with staining the front.

 

[TLS Guy]

I made my enclosure at 3.5 cubic feet. Any larger and I think my wife would have fainted. I enjoyed making it, it's not perfect but is a good start. I really like it so far, the bass is deep and tight and doesn't have that bloom like my polk sub. It is much more articulate and there is more of a snap to the music. I plan on making a grill for it since I didn't do a very good job with staining the front.

Here it is for 3.5 cu ft mid insert.

Type: Vented Box
Shape: Prism, square (optimum)
Vb = 3.5 cu.ft
Fb = 18.02 Hz
QL = 6.207
F3 = 20.7 Hz
Fill = minimal
No. of Vents = 1
Vent shape = round
Vent ends = two flared
Dv = 4 in
Lv = 27.98 in

Here it is for the low insert.

Name:
Type: Vented Box
Shape: Prism, square (optimum)
Vb = 3.5 cu.ft
Fb = 21.38 Hz
QL = 6.563
F3 = 20.3 Hz
Fill = minimal
No. of Vents = 1
Vent shape = round
Vent ends = two flared
Dv = 4 in
Lv = 19.03 in

I think you said you were using the mid insert. You can see that if your vent length is 17 inches you have a serious misalignment. It is very close for the low insert. Your vent is then short about 2 inches. I would put the low insert in the driver. I bet it will sound a lot better.

 

[flippo]

winisd

I got the length from winISD is winISD an inaccurate program? I will try the low insert after I become a lot more familiar with the sound now.

 

[TLS Guy]

I got the length from winISD is winISD an inaccurate program?

I have never used winISD. I have used the software of Bullock and White, which is now Box Pro and xover pro since 1984 and I can vouch for it. For the low insert you are close to the optimal box of 3.05 cuft.

The tuning just does not look right for a driver with a Qts that high, just by dead reckoning. I'm sure the alignment I gave you is correct. You are tuned too high at the moment. If you put in the low insert you will go deeper and tighter. Try it, that's an easy mod.

 

[flippo]

ok

ok I will try it on my next day off. By the way thanks for all the help and info you have given to me.

 

[annunaki]

With WinIsd and the mid Q insert I get a tuning frequency of 21.73hz using a 3.5 cu.ft. net enclosure and a 4" x 17" round port with flared ends.

The -3db point is 20hz with a port velocity of 44m/s, well within the audible range. This sub will have some serious issues down low with port compression and noise. Port noise will start becoming audible around 26hz with recommended power.

A larger vent would have been a much better choice.

 

[TLS Guy]

With WinIsd and the mid Q insert I get a tuning frequency of 21.73hz using a 3.5 cu.ft. net enclosure and a 4" x 17" round port with flared ends.

The -3db point is 20hz with a port velocity of 44m/s, well within the audible range. This sub will have some serious issues down low with port compression and noise. Port noise will start becoming audible around 26hz with recommended power.

A larger vent would have been a much better choice.

According to box pro if he uses the low insert Qts 0.34 the vent velocity will be 27 m/sec. I don't trust that WinIsd. There is no free lunch. I have used Bullock and White's software since 1984, and it has a good track record for me of predicting what actually happens.

 

[annunaki]

With the low Q insert I get very similar port compression numbers. I used the 4" dia. 17" long vent with flared ends. I have used WinIsd for many applications and it is always very accurate.

 

[TLS Guy]

With the low Q insert I get very similar port compression numbers. I used the 4" dia. 17" long vent with flared ends. I have used WinIsd for many applications and it is always very accurate.

So you are saying you get a vent velocity just below 30 m/sec with the low insert? If that is so the programs are close enough on this. He needs to use the low Qts 0.34 insert though, or he has a serious misalignment.

 

[flippo]

Low insert

I changed the driver to low insert and of course you were right. I ordered an elbow and some more tubing in order to get the vent length right. I am listening to Dark side of the Moon right now and it sounds fantastic.

 

[TLS Guy]

I changed the driver to low insert and of course you were right. I ordered an elbow and some more tubing in order to get the vent length right. I am listening to Dark side of the Moon right now and it sounds fantastic.

That is good news indeed! That gives me great satisfaction that you are now enjoying a superior product of your own making. Congratulations! It has been a pleasure to offer you my advice.

 

[jaxvon]

Now you just need to make a twin!