Dayton speakers & 4x12 to 2x12 conversion

Tim Skaggs

Tim Skaggs

Sep 28, 2002
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#1
Part 1; anybody have experience with Dayton drivers for a bass guitar cabinet? Many of the 12's have great specs, but I've never heard one that I know of. Just curious due to part 2.

Part 2; As decided in an earlier post, I'm converting a Marshall 4x12 sealed bass cab to a ported 2x12 cab & there are some choices on which I wanted TB'ers opinions.
~ speakers in opposite corners, or speakers vertical in two holes to one side, or speakers horizontal in the two bottom holes, or speakers horizontal in the two top holes? I'm thinking speakers in opposite corners with ports through the plywood plates blocking the unused holes.
~ divide the internal volume in two separate areas or let both speakers move the same internal air? I have a divider built, but not sure I need it. It's mostly to going to be an internal brace. The cabinet divides into two sections of ~2.5 cu. ft. each.
~ Any recommendations for a 12" speaker in a 2.5 cu. ft. box or two 12" in a 5.08 cu. ft. box? The Dayton PA310-8 looks good on specs, especially since this will be a tweeter-free cab.
PA310-8 12
 
#2
I think you might want to look more closely at the optimum enclosure volume (per driver) for a ported cabinet. Off the top of my head, that driver looks like it would do well in a smaller enclosure.

Why not sell what you have and build or buy something closer to your stated desire? My guess is that you will come out ahead this way. Good used cabinets are dirt cheap if you don't mind a heavier cabinet (which obviously you don't because of your driver and cabinet choice).
 
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#3
agedhorse said:
I think you might want to look more closely at the optimum enclosure volume (per driver) for a ported cabinet. Off the top of my head, that driver looks like it would do well in a smaller enclosure.

Why not sell what you have and build or buy something closer to your stated desire? My guess is that you will come out ahead this way. Good used cabinets are dirt cheap if you don't mind a heavier cabinet (which obviously you don't because of your driver and cabinet choice).
Click to expand...
I've got plenty of other cabinets to use for a variety of gigs both indoor and out. The guitarist in my band, who is also an old & good friend, gave me this old Marshall cab, & I'm just trying to semi-restore it, but make it sound like a bass cab instead of a re-labeled guitar cab. I currently have about $15 in grill cloth invested so far. I'm not going to spend much on it, just enough to make it sound decent at moderate volume. It might leave my shop for a gig, but more likely it will be for practice only, and for the novelty of having a "Marshall" cab. The "feet" of my Fender Studio Bass head do fit the wheel cups on top of the cab, so it will probably also be the storage location for that head. It's a hobby build for sure, but I'd like it to turn out to be somewhat useable. It will be my first ever 2x12 cab in a few decades of gigging.
 
#4
You will want to measure the interior volume of the cabinet, this will get you essential information to begin choosing a driver (and porting). From memory (pretty hazy as this was a long time ago), the Marshall bass cabinets were physically deeper than their guitar cabinet brothers though they looked similar from the front.
 
#5
Tim Skaggs said:
~ Any recommendations for a 12" speaker in a 2.5 cu. ft. box or two 12" in a 5.08 cu. ft. box?
Click to expand...
Didn't I already do that?
The Dayton PA310-8 looks good on specs, especially since this will be a tweeter-free cab.
PA310-8 12
Click to expand...
Look at the SPL charts. The Dayton is weak in the mids compared to Eminence. OK for PA or bass when used with a midrange driver, not so much used alone.
 
#6
Yes, but that was before I divided the box into two 2.5 cu ft. cells, and I didn't ask about speaker placement before at all. As indicated, this is a hobby project. I'm not trying to create a Motorhead rig with this, which is why I'm NOT going back with 4 12's in a sealed box. Here's a peek.
20180323_073357.jpg
 
#7
agedhorse said:
You will want to measure the interior volume of the cabinet, this will get you essential information to begin choosing a driver (and porting). From memory (pretty hazy as this was a long time ago), the Marshall bass cabinets were physically deeper than their guitar cabinet brothers though they looked similar from the front.
Click to expand...
Interior volume is 5.08 ft\3 or two 2.47 ft\3 cells; 28"x28.5"x11" or two at 13.625" × 28.5" × 11"
 
#8
The drivers should be vertical. Offsetting them a bit to one side will reduce internal resonances. Both in 5 cu ft or each in 2.5 cu ft is six of one, half a dozen of the other, the result is the same. A full shelf won't work much better than a single 1x2 connecting the middles of the two sides. What would be better is a pair of 1x2s connecting the sides, spaced evenly top to bottom, evenly front to back, plus two more connecting the top to the bottom and two more the front to the back.
 
#9
Tim Skaggs said:
Interior volume is 5.08 ft\3 or two 2.47 ft\3 cells; 28"x28.5"x11" or two at 13.625" × 28.5" × 11"
Click to expand...

Now run the calculations to see how they work. I don't think the drivers you picked will benefit much from the additional volume, but there might be much better choices (IMO).

Rick might know of something off the top of his head that would be a better match for the box, with better sensitivity, better low end extension and better mid voicing.
 
#12
I plugged it in to Speaker Box Lite for iPad. I don't currently have anything that will run WinISD.

Vb - 143.9 liters (5.08 cu. ft.)
Fb- I can plug values between 35 to 40 hz here and get the minimum F3
F3 - 45.7 hz
To tune the box to 36hz, it shows I need two 4" ports 6.8" long, but I usually tune by finding the freq for minimum cone movement with the speaker on its back and some rubber shavings on the cone, then adjust port length to tune. When I get the box tuned, my port lengths usually aren't very close to the calculated port length.

I thought I might get a lower F3 with a pair of speakers that have an Fs of 35 Hz, but when I adjust the box tuning to below 35 Hz or above 40Hz, the Fs starts climbing. F3 of 45.7 Hz will work for me, I'm not a fan of super low tuned cabs. I just got rid of an SVT 410 HLF for that very reason.

View attachment 2961697
 
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#13
Going by that graph I would tune a bit lower which should get rid of that bump at 70 hz or so which could make the cab very boomy and muddy. Is that graph for the BP122s or the daytons? I associate boomy cabs with too little volume and/or too high tuning so the bass sits too high because it's restricted from going down all the way (like trying to cram a scoop of ice cream into a too small cone). And in those cases, you get that low mid bump like in your graph. The compromise (there's always a compromise), is that you can get a dip in power handling if you tune too low. So the key is finding a good balance. Since your volume is basically fixed, you can just play with the tuning (and or driver choice) until you find what works best.

And I wouldn't put the drivers vertically unless you're going to put in a new baffle and put them in the center. This is never going to be a "perfect" cab engineering wise, so you could at least make it weight balanced so it's not an absolute PITA to move around, plus it will look dumb if you don't stagger them. I can't say for sure but I imagine the diagonal layout will rotate your horizontal/vertical dispersion by 45 degrees, which could be horrible (probably not) or it could allow for some neat tricks. I'm thinking the sound would change a bit depending on which side of the cab you're standing on.
 
#14
Omega Monkey said:
Going by that graph I would tune a bit lower which should get rid of that bump at 70 hz
Click to expand...
Tuning lower won't work well unless the cab is also made a lot larger. Getting rid of the bump requires a lower Qts driver, which usually means more expensive too. Also, tuning lower will have an adverse effect on excursion.

I plugged it in to Speaker Box Lite for iPad. I don't currently have anything that will run WinISD.
Click to expand...
If all you can see is the basic response it's almost worthless. WinISD 0.7 allows you to see that plus impedance, excursion, port velocity, maximum power and maximum SPL. The last two are critical, because they consider both the voice coil power and driver displacement. I took all of those and midrange response, plus your intent not to spend a fortune, into consideration when I recommended the Beta 12.
 
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#15
What good is excursion if your sound sucks to begin with? You just get a louder sucky sound. And for the OPs stated purpose, maximum excursion and power handling don't really seem like the highest priority.
 
#18
Rick James said:
Tuning lower won't work well unless the cab is also made a lot larger. Getting rid of the bump requires a lower Qts driver, which usually means more expensive too. Also, tuning lower will have an adverse effect on excursion.

If all you can see is the basic response it's almost worthless. WinISD 0.7 allows you to see that plus impedance, excursion, port velocity, maximum power and maximum SPL. The last two are critical, because they consider both the voice coil power and driver displacement. I took all of those and midrange response, plus your intent not to spend a fortune, into consideration when I recommended the Beta 12.
Click to expand...
When you ran two Beta 12A-2 in a 5 ft\3 box, did you find the box tuning is 52 Hz for the lowest F3 (which is 55.9 Hz)? Seein Trying to confirm if Speaker Box Lite is telling me anything worthwhile....
 
#19
agedhorse said:
Port velocity should be one of the graphs.
Click to expand...
Well, I think I'm finding the shortcomings of the "Lite" version. The application has hundreds of speakers in its database, you just go in and pick the brand / model. The problem seems to be that some T/S parameters aren't there for some speakers (value listed is 0). Graphs included are SPL, cone displacement, phase response, & group delay. With my question to Rick, I'm trying to determine if SB Lite is telling me *anything* of value. If the only thing I'm getting is decent box tuning for the selected driver, (realizing "decent" can be a choice, but decent for bass) that's of some value. If the box tuning for specific driver is not at least close, the whole app is of no value.
 
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#20
Tim Skaggs said:
When you ran two Beta 12A-2 in a 5 ft\3 box, did you find the box tuning is 52 Hz for the lowest F3 (which is 55.9 Hz)?
Click to expand...
F3 isn't the only consideration. It's important, but so are impedance, maximum power, maximum SPL and port velocity. If you can't see charts for all of those factors you can't make the best decision on the driver or the cab configuration.
 
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