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need help matching cabs

Bret Sparks

Bret Sparks

Feb 27, 2018
12
7
Osceola Ar
#1
I recently purchased a quilter bass block 800,
I currently use a 2x12-6.5+ horn 4ohm 1000w made by the evil DR sero I picked up used...I love the tone and durability of this cab!
I would like to add a 15" cabinet to that for outside venues.but I am lost to what ohm rating or watts i would need to match what I currently have!

could someone help this old dog out?
 
#2
Couple things....

A 1x15 will be a poor match for a 2x12, as the 15 will reach its limit well before the 212. You need a matching 212 cab.

The Bass Block is rated for a minimum of 4 ohms, so your single 4 ohm cab is pretty much it. Some will say that you may be able to run it at 2.67 ohms, but the back of the amp states 4 ohm minimum.

You need a 2 ohm stable amp with another 4 ohm 212, or pair of 8 ohm 212 cabs.
 
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#3
mmbongo said:
Couple things....

A 1x15 will be a poor match for a 2x12, as the 15 will reach its limit well before the 212. You need a matching 212 cab.

The Bass Block is rated for a minimum of 4 ohms, so your single 4 ohm cab is pretty much it. Some will say that you may be able to run it at 2.67 ohms, but the back of the amp states 4 ohm minimum.

You need a 2 ohm stable amp with another 4 ohm 212, or pair of 8 ohm 212 cabs.
Click to expand...
this is my first 2x12.....It would be safe to say i would be a happy fella with 2 of them ! never thought about that! would the wattage need to be exact?
 
#5
Whatever you get you would have to cross fingers the 2.7ohm total load stays ok at volume with that amp. I have seen the maker commenting that it's ''safe'' but not that it's recommended, because it could thermal out depending on variability of cabs.

It's a bit like TC rate their amp for a 2.7 load with their own cabs that they know won't overload it ( under load with impedance). The rating on the amp is 4ohm minimum.

If you were going to take that punt you could get someone to copy the 212 box tuning in a half size 8 ohm 112. You would have to accept the risk it shuts down on you when you give it some.

Other option might be carry on letting the PA do the work, put your 212 up on a riser to hear it better.
 
#12
Bret Sparks said:
I currently use a 2x12-6.5+ horn 4ohm 1000w made by the evil DR sero I picked up used
Click to expand...
can you provide a link to that cabinet: not familiar! thanks.

a series cable/box will get you 8 ohms from two, 4-ohm cabinets.

-or-

as okcrum suggested: another amp slaved to your existing amp solves the problem, gives you a backup amp, and allows for all kinds of 'rig shaping' in the future. plus: it takes the impedance issue off the table in most cases.

-or-
many 15" drivers will be fine with a 2-12 (check specs/power ratings!). the idea that you can't pair a 15 with a 2-12, effectively, is false. it just depends on your choices!

good luck! :thumbsup:


mmbongo said:
the 15 will reach its limit well before the 212
Click to expand...
sort of depends on the drivers being used, doesn't it? ;)
 
#14
can-of-worms-opened-you-have.jpg
 
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#15
Downunderwonder said:
It comes from the maker on the big thread that death is not likely on account of protection circuitry.
Click to expand...

Protections circuits are not perfect.

S-Bigbottom said:
Ok.
Possible protection shutdown may occur then. Maybe...
Click to expand...

Yes, or death.

JRA said:
a series cable/box will get you 8 ohms from two, 4-ohm cabinets.
Click to expand...

Poor advice, first the amp delivers half of it's rated power into what will be an 8 ohm load, and when placing 2 dissimilar cabinets in series, the cabinet's electro-mechanical action will interact with each other (generally in a very negative way). It will also affect the way the speakers function with regard to tuning within the cabinets (due to each driver affecting the other's effective TS parameters).
 
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#16
Bret Sparks said:
I recently purchased a quilter bass block 800,
I currently use a 2x12-6.5+ horn 4ohm 1000w made by the evil DR sero I picked up used...I love the tone and durability of this cab!
I would like to add a 15" cabinet to that for outside venues.but I am lost to what ohm rating or watts i would need to match what I currently have!

could someone help this old dog out?
Click to expand...

perhaps add a medium sized powered sub?

Invalid Link Removed
 
#17
agedhorse said:
Poor advice, first the amp delivers half of it's rated power into what will be an 8 ohm load, and when placing 2 dissimilar cabinets in series, the cabinet's electro-mechanical action will interact with each other (generally in a very negative way). It will also affect the way the speakers function with regard to tuning within the cabinets (due to each driver affecting the other's effective TS parameters).
Click to expand...
not sure about "poor advice," but my take may not have been about the 'ideal' either. ;) it was a practical way for the OP to hear his idea(s). sometimes a player may want to actually hear the beast before considering whether to take responsibility for the lack of 'ideal'.

also: in the wild: sound-folk have made and carried series boxes in their tool chests as 'de rigueur' for unpowered cabinets for decades. it's rarely, if ever, an "ideal" circumstance to have to use one, but it's always "ideal" to have one if/when you need it. the OP's bass rig is probably not as 'mission-critical' and his amp can certainly deliver.

your response to my post seems to invite the "mixing cabinets" conundrum: where sometimes it's great, sometimes it's not so great, but it's always a crapshoot. it is rarely fatal, however, even for the drivers! when a poor pairing is made: we usually say "that doesn't sound good to me --- it's not what i wanted/expected/hoped" and then we try something else.

mmbongo said:
What specific 15" do you have in mind that will match the output of that 2x12 cab?
Click to expand...
nothing specific. i didn't recommend a driver --- i implied that a search was in order. i know nothing about the 12s. i was taking exception to what i regarded as the 'herd sense' i interpreted from your post. my apologies to you if you know something about those 12s (those cabs) which prohibit the use of a 15 in a separate cabinet. :)

filter for 4-ohm, 15s:
https://www.parts-express.com/
http://www.usspeaker.com/
 
#18
Mixing cabinets is never a crapshoot when they are designed to be mixed by somebody who knows how to design speakers.

Series connection of speaker cabinets works fine for identical cabinets. Rarely does it work well in the OP's scenario for the reasons I said earlier.

As a pro audio guy of 40 years, I never found a need for a series box or cable, but what do I know...
 
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#19
mmbongo said:
What specific 15" do you have in mind that will match the output of that 2x12 cab?
Click to expand...
Not with this amp though.

Something like the Mesa Subway 15 could work with this cab.
it is a strong 15 that can play well with multi cabs like two 1x12's.

Except for the exact tone created all three speakers could be working good together as the 2x12 is a 4 ohm cab, so each speaker is 8 in that box. The 15 is 8 ohms also, so all speakers would be getting the same power distribution. This is equaling 2.67 ohms so again, not for the OP's amp.

Just because the 12's are in the same box together, hooked up it is the same as having two 1x12's stacked with the 15.
Except for the tone and a bit of the wattage this is the same as having the Subway 15 with two Subway 1x12's stacked.
 
#20
S-Bigbottom said:
Not with this amp though.

Something like the Mesa Subway 15 could work with this cab.
it is a strong 15 that can play well with multi cabs like two 1x12's.

Except for the exact tone created all three speakers could be working good together as the 2x12 is a 4 ohm cab, so each speaker is 8 in that box. The 15 is 8 ohms also, so all speakers would be getting the same power distribution. This is equaling 2.67 ohms so again, not for the OP's amp.

Just because the 12's are in the same box together, hooked up it is the same as having two 1x12's stacked with the 15.
Except for the tone and a bit of the wattage this is the same as having the Subway 15 with two Subway 1x12's stacked.
Click to expand...

I’ll agree with all that. The Mesa 15 would do it. But like you say, not with this amp unless you have two of them.
 
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