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Cabinet tuning help

randyg

randyg

Jul 10, 2010
174
17
68
Creedmoor N.C.
#1
Ok , so I've been working on my diy 2-15 cabinet on and off for a while now and I have a question. The internal dimensions are 35"x23.5"x12" for a net volume of about 5.3 cuft. It has 4 3.75" diameter flared ports that came 7.63" long and it has 2 3015's in it. My calculations came up with a tuning freq of 46.5hz. I did a rice test and the grains never stopped bouncing , but bounced a lot less in the 42hz range. I shortened the ports one at a time by 1/2" each and the rice movement slowed closer to the 47 to 48 hz range. I have tried the cab lined with thin quilt batting as well as 2" thick white fiberglass insulation. I have also tried it with one port blocked and one tube removed , which should greatly lower and raise the tuning freq. Here is the question , it sounds great in the mid and high ranges , but the low notes , especially the open E string , do not sound full and strong. I have to really crank the bass on my SVT-CL or it sounds hollow and mid rangey. Describing tone is difficult , but it does not have much low end. It also sounds the same when I was playing around with the port tuning. Nothing I did changed the tone much at all. Any advice on what tuning frequency to shoot for? It is built from 3/4" 13 ply baltic birch , glued and screwed. Maybe I just don't get along with the tone of the 3015's. My favorite cabinet is an Ampeg 610hlf which some people find too bassy. Thanks for any help.
 
#2
Double check that the drivers are wired 'in phase'.

If they are in phase, you can increase the prominence of the bass by tuning higher, say around 55Hz. Seems counter-intuitive because you will get less deep bass, but that will make the bass more prominent overall.

If that doesn't work consider trying a different driver (like the Faital Pro 15PR400).
 
#4
I've checked the phase issue and it's ok. I had these speakers in a Peavey 2-15 shallow cabinet and to me they did not have that full , round big bottom sound the stock speakers had in that cab , but I figured it was that speaker/cab mismatch problem. I'll try tuning the cabinet higher and maybe close the ports and try it sealed , but I'm not getting what I was expecting from it. Maybe I've been hearing that bottom heavy 610hlf too long.
 
#6
The speakers are the 3015. I got the port tubes from Parts Express , part number 260-480 and put four of them down one side. It's built to look like a Greenboy Dually and has about the same dimensions , but I have no idea what port tubes are in the Dually.
 
#8
randyg said:
I've checked the phase issue and it's ok. I had these speakers in a Peavey 2-15 shallow cabinet and to me they did not have that full , round big bottom sound the stock speakers had in that cab , but I figured it was that speaker/cab mismatch problem. I'll try tuning the cabinet higher and maybe close the ports and try it sealed , but I'm not getting what I was expecting from it. Maybe I've been hearing that bottom heavy 610hlf too long.
Click to expand...

The key here may be your expectations. The 3015's in a 'Dually' cab will NOT have 'that full, round big bottom sound the stock speakers had in that cab', at least not without some serious EQ. Note that if your cab's internal volume is less than the dually its bass will not be as full. It will indeed be bass shy as bgavin pointed out. As I said earlier, you can regain some bass fullness by tuning higher.

If you followed the instructions that came with the port kit you should be fine with respect to tuning frequency.
 
#9
Go on parts express. Search precision ports. Pick a 3" diameter flared port. For example then Click on the port calculator. Add in the simple info on the left hand column and it will give you the lengths for both straight and flared ports

Just did it with my 2-12 emenence neo cab. Unbelievable! Totally fantabulous.
 
#11
Make it bigger? :D


Your size is pretty compact for a 215. That combined with those drivers being fairly strong in the mids may sound bass shy overall. Can try raising the tuning some.

Box panel resonances working against your output goals could be another contributor depending on your bracing scheme. Thick walls with little to no bracing is not as stiff as a bit thinner ply with more/better bracing.

Are the drivers brand new? Takes a bit for break-in/suspension loosening up. Could try letting a LF test tone ( 30-40hz, pretty low power but enough to get the cones moving ) run through it overnight, and listen again after.
 
#13
How did you check for phase? I just finished a 215 cab and on the first test drive, it had no bass and generally sounded horrible. I didn't even consider the possibility that I had wired the drivers out of phase. I had been very deliberate and methodical in the wiring and, frankly, I didn't think I could have made such a silly mistake. But I did. Didn't realize it until I did the battery test.
 
#14
I really thank everyone for the help. It was with help from this site I was able to get this cab built. It really sounds good , a beast in the mids and highs , and the low end is good too with some EQ boost. My expectations may be a good point as I had never heard a modern 2-15 with 3015's in it. I have also not used it in a band mix yet , only solo and it may shine in a rock band with Les Pauls and Marshalls. I'm going to trim the port tubes to a little over 50hz , Duratex it and rock the crap out of it.
 
#15
I did the battery test again a little while ago to make sure. It's ok. The speakers are still pretty new and I know the low end gets better as they break in. My Avatar 4-10 did that. I have the baffle braced to the back between the speakers and thought about bracing side to side , but with the 3/4" 13 ply , it seems pretty stiff. I may add a brace or two just to be sure.
 
#17
If I understand correctly , the Fob is the tuning freq of the cabinet , right? I'm a little unclear on what to do to get the low freq up. I've read the spec sheets for the speakers and tried to figure it all out but most of it is still over my head. That's why I tried to copy some proven designs. I'm close , but not quite there yet.
 
#18
The size, tuning, new drivers, and only hearing it solo tells me I wouldn't alter it to much until it's briken in a little and you've had a chance to hear it with the band.

It's a whole lot easier to chop port tubes shorter than it is to stretch them. :smug:
 
#19
FWIW, if you have an android phone, there is an app called True Tone that'll do sine, square, triangle and sawtooth waves from 1 to 21000 hertz.

Pretty handy for checking tuning, just rig up a 1/8" to 1/4" or speakon to run from phone to cab.
 

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