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Need third opinion - cab tuning

W

Wayne8

Sep 25, 2008
378
5
69
Jackson, Mississippi
#1
I had emailed Eminence customer service asking how to tune a 2X15 cab with two of the 3015's. I didn't get an answer right away so I asked on here and DukeLeJeune replied saying to go with two 4" ports (one in each section - top and bottom are serated by a partition) 4 inches long. Then after that, Anthony at Eminence replied to my email and he suggested two 4" ports (one per section) 9 inches long.

Now, Duke, being in the speaker design business, ought to know what he's talking about. So should Emincence. But there's a huge difference between the two suggestions. Can someone else take a look at my specs and chime in with suggestions, please?

If I go with 9" long port tubes in an 11 1/2" deep cab, after I line it with 1" foam, there's only going to be about an inch and a half clearance from the end of the tube to the foam, would that work?

Anyway, here are the dimensions of my cab (2x15 with a partition seperating top and bottom). To be filled with Eminence 3015's (already bought, not here yet). It's a Peavey cab with weird triangular ports (6 1/2x6 1/2x9) that I'm going to seal and cut 4" holes. I just need to know what length tubes I need.

24" wide, 18 1/2" tall (each section), 11 1/2" deep. Thanks in advance for any help y'all can give me.

By the way, I play a 4 string Jazz, flats, Classic Rock & Blues, if that helps.

Thanks!
 
#2
I suggest learning to use WinISD Pro and decide for yourself. Measure internally with some accuracy and don't forget to subtract things that take away from internal volume like bracing, handles, and the ports themselves - and of course the drivers (maybe 180-200 ci per 3015).

Myself, I think around 52-55 Hz is a good tuning for 3015 for bass guitar use in 3.0 cf, but what I would tune to somewhat changes depending on enclosure size.
 
#3
Wayne8 said:
I had emailed Eminence customer service asking how to tune a 2X15 cab with two of the 3015's. I didn't get an answer right away so I asked on here and DukeLeJeune replied saying to go with two 4" ports (one in each section - top and bottom are serated by a partition) 4 inches long. Then after that, Anthony at Eminence replied to my email and he suggested two 4" ports (one per section) 9 inches long.

Now, Duke, being in the speaker design business, ought to know what he's talking about. So should Eminence. But there's a huge difference between the two suggestions. Can someone else take a look at my specs and chime in with suggestions, please?

If I go with 9" long port tubes in an 11 1/2" deep cab, after I line it with 1" foam, there's only going to be about an inch and a half clearance from the end of the tube to the foam, would that work?

Anyway, here are the dimensions of my cab (2x15 with a partition seperating top and bottom). To be filled with Eminence 3015's (already bought, not here yet). It's a Peavey cab with weird triangular ports (6 1/2x6 1/2x9) that I'm going to seal and cut 4" holes. I just need to know what length tubes I need.

24" wide, 18 1/2" tall (each section), 11 1/2" deep. Thanks in advance for any help y'all can give me.

By the way, I play a 4 string Jazz, flats, Classic Rock & Blues, if that helps.

Thanks!
Click to expand...
The answer is as obvious to me as it was with King David the correct answer is six or so inches maybe when duke measured it he was eating beans and all the dudes from eminence had just come back from a ride in a helium balloon.:D
 
#4
Wayne8 said:
It's a Peavey cab with weird triangular ports (6 1/2x6 1/2x9) that I'm going to seal and cut 4" holes.
Click to expand...
Don't. Those triangular ducts are 21 square inches in cross-section, which is about right for a fifteen. Four inch round ducts are only 12.5 square inches. OK for a twelve, but not a fifteen.
 
#5
I tried using WinISD and also Eminence's software. I kept having trouble and could never get either to work for me. I did forget to say that there are braces inside with dimensions of 10 1/2 long, 3/4 thick and 1 3/4 tall for one and 24 long, 3/4 thick and 3 3/4 tall for the other.

If no one can tell me what length the tubes should be from that info I guess I'll try both 9 inches and 4 inches. And just so I'll know, is longer supposed to be deeper bass or less bass?

I just thought that someone who already knows how to use the software could maybe run my numbers.

Thanks anyway.
 
#7
So Bill, you're saying leave the triangular ports and it'll sound alright without any tubes? That's the only reason I was going to seal the triangles, I couldn't figure out how to properly port them. But if the triangular cutouts are okay without any tubes in them, that'll sure save a lot of trouble.
 
#9
Hi.

IIRC the Peavey "ports" are cut-outs on the baffle? The effective lenght then being the baffle thickness.

A bit on the short side I think ;).

I didn't run the numbers on WinISD or the Eminence designer, but an inch between the port end and the insulation can create problems. I like to have at least 1/2 the port diameter distance between them, preferably the port diameter. But I don't do this for living and not very often as a hobbyist either, so take the pro's advice.

Regards
Sam
 
#10
You're right T-Bird, just the cutout in the baffle, so I guess the port length is 3/4". Sounds like Bill was saying that's all that's needed. I guess I'll try it and go from there. I can always go back and do something else with it if necessary.

Does a longer or deeper port make it bassier? Is there such a thing as too bassy?
 
#13
Okay, after a whole lot more reading, I used WinISD Online and I think Duke was right. The guy from Eminence was talking about 2 vents per section, 4" diameter, with a tube length of 9". Which is what WinISD said at 45 hz (that's the tuning he said this would give me). But if I went with one 4" vent, 4" long, it gave me 41hz, which is what Duke said. So I'm going with that.

Thanks Duke, and others. I know I've been a pain lately with several threads about speakers and such but I'm almost there now. Thanks again everybody.
 
#14
Wayne8 said:
You're right T-Bird, just the cutout in the baffle, so I guess the port length is 3/4". Sounds like Bill was saying that's all that's needed. I guess I'll try it and go from there. I can always go back and do something else with it if necessary.
Click to expand...
Your post had three dimensions, I assumed the third was the duct length. In any event those ports will tune your cab to about 70 Hz, which is way too high. Add plywood ducts on the hypotenuse legs 8 inches deep and you'll be around 45-50 Hz.
 
#15
I use the primitive way to fine tune ports.
Put the cab on his back with the front bafle on top, now put some salt in the speaker cone, and send the frequency (50-55Hz) which you can find in winisd or a online frequency generator trough your amp.
You will see the salt wil move en jump on the cone, if the tunning is NOT correct.
The salt wil stop moving if the tunning is correct, en there will be more sound comming from the ports then from the speaker at that tunning frequency
 

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