series 6th order finally rebuilt!

[brent379]

alright so I decided to try out a series 6th order...first build was a complete fail lol. rear chamber was about 3 cubes at 28hz ported into 1 cube at about 65hz. first problem...box would not fit into the trunk lol. it would have fit but it would have to be built in the trunk. so I put it on the back seat to at least see how it sounded and it " washed" out hard. didn't blow the woofer though. so I took it out..tore it down and came up with a new design. here are a few pics.

rear chamber is 1.27 cubes at 28 hz with 19.5 sqin port area. and front chamber is about 1.8-1.9 at 70hz with 55 sqin port area. unfortunately this is only running at 2 ohms. bought this type r for 40 bucks. was hoping for dual 2 ohm but its dual 4 :/ o well. for it only getting maybe 600rms....it does DAMN good!!!

I don't have any kind of termlab or anyway to measure output and actually do testing. but after I got this one in the trunk I beat on it HARD for a good 45 minutes to an hour straight...no homo. and it plays into mid to low 20s very well. played some decaf...e40...and some other stuff that got some pretty hard low drops and it didn't bat an eye at any of it! I was very impressed. there is a small....idk.. for lack of better terms..."dip" in the output in the higher frequencies but it don't seem to bad. one thing that blew me away was how much bumper flex I had at 26hz....it was moving a good 3/4 to one inch. this is definitely NOT a good thing lol. and I got the trunk deadened pretty good too. but this was built as just a test box. something I wanted to try and it impressed the s*** out of me for only being 1 12 on about 600rms. now i know that for the next one once i get a good woofer again i will have to seal it off from the trunk.

just something i wanted to share that i learned thru this...and anyone please correct me if im wrong especially since this is my first 6th order.

when it comes to how much port area to run on the inside chamber...if you research 6th orders you honestly don't find too much useful info to help you out. i researched for a few days trying to find a direct answer on this and couldn't. all i could find is people saying to run 8-10 sqin port area per cube....or to run the smallest port possible to help with cone control and so on. i really think that this is NOT the case. if you have built a box with not enough port area you know it sounds like 60mph winds coming out of the box. well...when i first built this 6th order BEFORE i rebuilt it i used a 4 inch aero flared on both sides to port the rear chamber into the front. and well guess what. i heard the 60mph winds inside the box lol. so! when i was redesigning this box i decided to go with my gut instinct and use winisd to get my port velocity under 75ft/sec with the smallest port possible. and the outcome was successful!!!!! and im probably wrong on this too...but i think that port velocity helps with cone control. granite there are many other factors that go into cone control....but lower port velocities help keep the port "pressurized" instead of it just blowing air out of a hole. like i said...im probably wrong on that...but to me it makes sense.

its pretty challenging to find good info on 6th orders and i think its partially because yes...they can be a pain in the a** to figure out and design especially dealing with 2 ported chambers. but port velocity doesn't lie. so if your like me....someone who wants to try a 6th order and doesn't know exactly which way to go when figuring out the ports....use winisd or something that will show you what your port velocity is and start with that. just my 2 cents.

like i said before...this is my first time around with 6th orders.so if there is an expert out there that knows better then please correct me where im wrong! im trying to learn too! and for being my first 6th order...even though i had to rebuild it once...im pretty proud of it! definitely looking forward to building another one with a better woofer with more power

[brent379]

_{and yes....that is 3 layers of 1/2 inch mdf for the woofer baffle. didn't have enough scrap pieces to make a new baffle and both home depots i went to were out of 2x4 sheets of 3/4 inch mdf...... its still a 11/2 baffle so it works lol}

[mrd6]

I like it! If you dropped your front tuning down to ~55-65hz i bet that "dip" will disapear and youll just lose a bit of output up at very top.

[brent379]

Thank you sir!!!! That's what I was thinking of doing for my next 6th order. See with a series tuned 6th the front port lengthens the rear port so in all actuality...my rear chamber is probably tuned around 25-26. And with the front being at about 65-70....that's what...almost 2 octaves apart?? I think my next one I want to go only 1 octave apart. And personally I think the rear chamber could go to 1.5 cubes instead of 1.2. And I think the front chamber could use a tad bit more port area. But for now it will definitely get me by lol build and learn right

[Krakin]

I need to start researching some on 6th orders. I know enough about 4th orders to get me by, but when it comes to 6ths, nope.

Otherwise, nice box (from what little I know and from how much you wrote you did).

[brent379]

Lol Ya 6th orders are a completely different animal that's for sure. Idk if it will help but I started with the rear chamber size. Im just went with alpines "optimum" size chamber. I think their optimum chamber size was 1.3 cubes....Well with woofer displacement I'm at 1.27. Close enough lol then I just shot for a 2:1 radio front to rear...which I ended up a tad short of a 2:1 but o well. That's what happens when you don't just start from scratch lol I would say give it a shot man it's definitely worth trying! And if you already understand 4th orders it's just a matter of porting the sealed chamber basically. Just don't skimp on port area!

[Jessica]

very nice enclosure man. How do you cut those tiny triangles? I always struggle with the delicate pieces even with a table saw. Just so damn hard to work with.

[brent379]

Thanks man! And I won't lie...those tiny triangles are a bitch! I must have cut 20 of them and it off 20 NONE were correct lol I tried putting all the math into it and it was just to much. So I figured out a easy way to do it.

Take your piece of wood and cut a 45 degree angle. Then. Put your blade back to 90 degrees and cut the 45 off! It's really not hard. If you don't understand what I just said I can go get a piece of wood and take a couple pics for you.

[bcbrassard]

Nice box, mad skills and i bet it sounds good.

[brent379]

Thanks dude there are a couple things I will definitely do different on my next 6th order...but for being my first one and such low power this thing is really loud lol. If I knew how to put a video up I would do it so everyone could see