Sub placement, does it matter?

[MellowHype 10+ year member]

Heat Moulded Port Flares
Something like this to flare ports. Ive seen a thread where someone used a pot of hot oil to evenly heat large PVC he claimed that you need a lot of pressure to force the pipe open so he built some sort of lever press to smash down the PVC onto the mold.

interesting link with some good stuff but i dont have access to the tools to follow much from that

im just gonna get my 6"x14" pipe and flare both ends using a heat gun and a metal bowel, saw it in half, cut out a 6" hole in the box and assemble the port in the box and glue/tape together, similar to this

 

[hispls 5,000+ posts]

interesting link with some good stuff but i dont have access to the tools to follow much from that
im just gonna get my 6"x14" pipe and flare both ends using a heat gun and a metal bowel, saw it in half, cut out a 6" hole in the box and assemble the port in the box and glue/tape together, similar to this

Use Google. Ive seen a method with a much simpler mold and the press lever was just some 2x4s

 

[MellowHype 10+ year member]

Right, ive made a port with two flares, but im not sure whether theyre flared enough and its the best i could do with the bowl i was using.

Hopefully you guys think that looks ok, i will be painting it tomorow if so. (Edit: The cut out for the port is already in place leaving barely any room for more of a flare, i guess its staying as is, should have waited to get some advice but i wasnt thinking lol)

I have a coupler to join two peices so once i know the port length i will cut it into two and im ready to go

Could anyone tell me how long it needs to be for a target of 32hz? and also the displacement of it at the length needed for that? Im going to try 32 and if im not happy ill raise it slightly and aim for 36hz for more SPL.

The box dimensions (external) are 33" wide, 17.5" high and 15" deep. 0.75" MDF

The displacement of the sub is 0.10ft^3, and im using 2.

The inside of the PVC is 6" and the outside 6 19⁄64"

Appreciate any help!

 

[MellowHype 10+ year member]

This is what im using to join the pvc

 

[MellowHype 10+ year member]

Using the 12Volt calculator i calculated that the port needs to be 14.5" long for 32hz, but i dont know how accurate that is.

Also would that be measuring from where the flare straightens out?

 

[MellowHype 10+ year member]

Wasnt taking into account displacement of the subs in the above post ^

I went with 15.5" port giving me 34hz after displacement, heres how it looks.

As you can see the flare sticks out a bit and its going to have to stay like that, im just going to use the strongest sealant i can find to seal around (see 2nd pic) and it should keep it in place..

Can i get any opinions?

 

[ancorp 10+ year member]

Looks great, did you put the baffle on and fire up the Type Rs yet?

 

[MellowHype 10+ year member]

Looks great, did you put the baffle on and fire up the Type Rs yet?

Yep i have, however i made the mistake of assuming that going from 700 rms @ 2ohm to 1000 @ 1 ohm would mean turning my gains up, so i left the gains how they were and played some songs on full. Luckily it wasnt for too long though and i realise that my voltages need to be alot lower so i could have killed my amp.

Ill be re-setting gains in a little while

 

[hispls 5,000+ posts]

That looks very nice for a first box! I'd have liked to see a bit more flare, but anything is better than nothing.

 

[MellowHype 10+ year member]

That looks very nice for a first box! I'd have liked to see a bit more flare, but anything is better than nothing.

Its actually my second, and the 1st one was pretty bad lol. but thanks anyway

I know i really wished i spent more time on the flare, its just the only metal bowl i had would only flare it as far as that or the pipe would start collapsing in, needed a bowl with a smaller base. Would have been nice to flare more and screw it in flush.

Ive just set my gains again, and the two 12's are now no louder than my single R. Yesterday when i hadent touched the gains from before i bumped at full volume and was quite impressed, i could feel it in my throat lol

My leads for the meter i used before had broken so i found a pair at my work and tried them. The resistance from pos to neg wires on the meter was 1.5 ohm.. So i then tested the subs wires and it showed 2.5 ohm, so i guessed maybe they where abit out but just 1.5 ohm out? (my subs are or should be wired to 1 ohm)

When i first played the test track the multimeter was showing 50volts! this was gains untouched from when i set it to 700 rms for my single 12.

and i know for a fact that before with my brand new meter (although it was very cheap) was showing my target of 37 volts. I also played that sub at that voltage for over a year with absolutely no problems.

I went ahead and used the meter to back down from 50v to new target of 31volts (1000 rms @ 1 ohm), and the result was two R's sounding identical spl wise to my single R

So im hoping that the wires are just out as two subs, and a large improvement on box should definitely not be the same as my single R.

EDIT: I had also used the leads in another meter i found at work and it showed the same 50volts, so i think it has to be the leads

 

[ancorp 10+ year member]

I personally never used any DMM to set anything. Just cranked it until I felt I was approaching distortion/clipping or low voltage. Turn it up and get those suckers moving.

 

[MellowHype 10+ year member]

I personally never used any DMM to set anything. Just cranked it until I felt I was approaching distortion/clipping or low voltage. Turn it up and get those suckers moving.

Im now waiting until wednesday until the new leads get here, if its showing the same figure i might just do that.

Do you use a test track like 60hz or just chose one of your louder songs when doing it by ear?

 

[ancorp 10+ year member]

No tones, just grab my favorite bass heavy songs.

These Type Rs are brand new?

 

[MellowHype 10+ year member]

No tones, just grab my favorite bass heavy songs.
These Type Rs are brand new?

Yep brand new, annoying comparing the price to what you pay over in US, think i saw them on amazon.com for $120 each, i payed £140 each which is like $240.

Im now tempted to buy this 2nd hand Hifonics Brutus BRE (Elite), capable of 2500 @ 1 ohm, its just i dont know how you can test if an amp is in good condition when 2nd hand. Previous owner could have turned gain to max, blown a sub and just wants to sell it. Guess thats just the risk.,

Could anyone help me with my subsonic filter? Ive got a song that has a 26hz frequency that my subs miss because of how its currently set. Am i good to hit 26hz in a box tuned to 34hz?

Im using a tutorial on here just want to make sure im correct

SSF frequency by using the formula: SSF = Tuning*3/4 - 34hz x 0.75 = 25.5

Calculate the desired SSF voltage by using the formula: SSF_Voltage = 0.707*Sub_Voltage - 0.707 x 31.62 = 22.35 (that is going by 'Sub_Voltage is my gains setting voltage)

I then get my 25 hz test track and turn down the subsonic untill i see 22.35 volts?

Greatly appreciate all of your help in here btw helped me learn alot

 

[hispls 5,000+ posts]

Where are you getting these voltage numbers? How have you verified the impedance of your sub at all these frequencies that you're testing?