How to wire speakers in a cab

[Alder Tollner]

Ok so, i have this crazy idea that i want to see if it’s possible. Basically i want to get a new bass head (like an old 70s svt, b-25, or a v-4b) and when looking for cabs i stumbled across the ampeg iso vent cab. Its a set of 2 10s on top and in the bottom 2 15s facing each other, very unique and weird. I was happy and decided that that would be my cab. Then i learned it weighs 130 pounds. Now i know im not playing any shows right now but this is basically going to be my setup for a long time, and lugging a 130 pound cab plus a 70 pound head does not seem fun. So then i looked at other cabs, but i couldn’t find one that had both 10s and 15s. So then i thought to myse “Ill just build a cab the way i want”. So my thinking is 1 10 in the top left, 2 12s, one on the top right and the other in bottom left, and 1 15 in the bottom left. In my mind this would be amazing, but i need to know if it would even be possible to wire this and not have it blow up. Most of the heads i have been looking at are typically around 400 watts @4 ohms with some allowing 2 ohms or 8. Please let me know if ill be able to live my dreams!!

 

[Killed_by_Death]

There's more to building a good-sounding cabinet than just throwing speakers into a box.
The others will be along to explain.

My recommendation is to build (or buy) each one as a standalone cabinet & then daisy-chain them together.

 

[daveman50]

There are threads on the topic of mixing full-range drivers in one cabinet -- for example, Mixed driver cabs. The collective wisdom of this TB site is negative on the idea. I suggest you do more research and think about why this is your dream... there may be (is probably) a better way to realize your sonic goals. Good luck!

 

[Wasnex]

Ok so, i have this crazy idea that i want to see if it’s possible. Basically i want to get a new bass head (like an old 70s svt, b-25, or a v-4b) and when looking for cabs i stumbled across the ampeg iso vent cab. Its a set of 2 10s on top and in the bottom 2 15s facing each other, very unique and weird. I was happy and decided that that would be my cab. Then i learned it weighs 130 pounds. Now i know im not playing any shows right now but this is basically going to be my setup for a long time, and lugging a 130 pound cab plus a 70 pound head does not seem fun. So then i looked at other cabs, but i couldn’t find one that had both 10s and 15s. So then i thought to myse “Ill just build a cab the way i want”. So my thinking is 1 10 in the top left, 2 12s, one on the top right and the other in bottom left, and 1 15 in the bottom left. In my mind this would be amazing, but i need to know if it would even be possible to wire this and not have it blow up. Most of the heads i have been looking at are typically around 400 watts @4 ohms with some allowing 2 ohms or 8. Please let me know if ill be able to live my dreams!!

You don't want a bunch of different drivers sharing the same chamber in the cab. The primary issue is the drivers need to balance, so the more powerful driver does not dominate and destroy the weaker drivers.

The only cab I can think of that uses 10s and 15 is the Mesa PH1000 or PH1200. I believe these break the rule I just mentioned and all five drivers are in the same chamber. Most people don't consider them great cabs.


Also, as @Killed_by_Death mentioned, you don't typically get very good results by throwing random drivers in a random cab. Drivers have a range of electromechanical parameters called Thiele Small (T/S) parameters. There are computer programs that are used to model the low frequency performance of speaker designs. To do this, you load the T/S parameters, volume of the box, and port dimensions of the box.

An expert can look at T/S parameters and get a ballpark idea of what size and type of box to start with.

Based on the program, the resulting model produces a range of graphs that might include frequency response, excursion, power handling, vent air velocity, etc.

As example of what modeling looks like, I have attached the Eminence Cab Design doc for the Deltalite II 2512

 

[S-Bigbottom]

There is a reason that Ampeg cab was a short lived product and why you do not see cabs like them and what you are pondering.

What you want to do will be limited by your weakest speaker, one will die while the others are just waking up, or you will just not get the max performance of the stronger speakers without proper crossovers on each.

Each speaker will need to be in their own chamber in said box or they will shred each other apart, adding weight and size, you may well be above the weight of that Ampeg.

 

[Michedelic]

You be better off getting two identical 2x10” cabs for flexibility/portability, or perhaps two identical 1x12”. Much depends on what head you get in terms of power and what ohm load is optimum for it.

 

[abarson]

Ok so, i have this crazy idea that i want to see if it’s possible. Basically i want to get a new bass head (like an old 70s svt, b-25, or a v-4b) and when looking for cabs i stumbled across the ampeg iso vent cab. Its a set of 2 10s on top and in the bottom 2 15s facing each other, very unique and weird. I was happy and decided that that would be my cab. Then i learned it weighs 130 pounds. Now i know im not playing any shows right now but this is basically going to be my setup for a long time, and lugging a 130 pound cab plus a 70 pound head does not seem fun. So then i looked at other cabs, but i couldn’t find one that had both 10s and 15s. So then i thought to myse “Ill just build a cab the way i want”. So my thinking is 1 10 in the top left, 2 12s, one on the top right and the other in bottom left, and 1 15 in the bottom left. In my mind this would be amazing, but i need to know if it would even be possible to wire this and not have it blow up. Most of the heads i have been looking at are typically around 400 watts @4 ohms with some allowing 2 ohms or 8. Please let me know if ill be able to live my dreams!!

1. Amplifiers are rated to work with a minimum speaker load or greater, but not less. This is very important to understand, regardless of the make of amplifier. Example: an amp rated for 4 ohms minimum has no problem powering an 8 ohms cabinet as (8 > 4).
2. The Isovent gets lots of derision here, and there's a number of reasons why no-one else made a similar speaker, weight being one of them.
3. Stuffing random speakers of various sizes into an unengineered box is a stupendous waste of time, material and money.
4. There are properly engineered cabinets with different sized drivers, if you absolutely must go that route. Here are some current offerings:
TC1510 – Traynor Amps
El Whappo
Cabinets | Schroeder Cabinets | Bass Cabinets | California (These exist. I'll not comment about how I think they sound.)

 

[Michedelic]

Ok so, i have this crazy idea that i want to see if it’s possible. Basically i want to get a new bass head (like an old 70s svt, b-25, or a v-4b) and when looking for cabs i stumbled across the ampeg iso vent cab. Its a set of 2 10s on top and in the bottom 2 15s facing each other, very unique and weird. I was happy and decided that that would be my cab. Then i learned it weighs 130 pounds. Now i know im not playing any shows right now but this is basically going to be my setup for a long time, and lugging a 130 pound cab plus a 70 pound head does not seem fun. So then i looked at other cabs, but i couldn’t find one that had both 10s and 15s. So then i thought to myse “Ill just build a cab the way i want”. So my thinking is 1 10 in the top left, 2 12s, one on the top right and the other in bottom left, and 1 15 in the bottom left. In my mind this would be amazing, but i need to know if it would even be possible to wire this and not have it blow up. Most of the heads i have been looking at are typically around 400 watts @4 ohms with some allowing 2 ohms or 8. Please let me know if ill be able to live my dreams!!

Another overall aspect of this is that, while you seem fixated on utilizing an Ampeg amp, you have three entirely different power platforms listed. What is your band/gigging situation? How loud do you realistically need to be, what instrumentation are you up against? Understand that owning/operating a classic SVT head is a commitment, and what speaker options you select to pair with it depends on your requirements, and whatever that selection may be will affect your sound.