series/parallel

i just read a post that 12VOLT answered ( https://www.the12volt.com/installbay/display_topic_threads.asp?ForumID=2&TopicID=7571&PagePosition=1#thread)  and i would like to know  how to figure out my dilema...  i have 2 customers, and they both want the same display in their trunk.  #1 has three sony explodes, one of them is a DVC, how would the set up go if he wants to play them as a 2 ohm load to the amp?  i thought it would be...series the SVC together (8 ohms +-+-) and have the DVC (++-- 2 ohms) parallel to the other speakers making the load 2ohms...does this sound right?

#2 has three MTX road thunder and wants to play them out of a 140W X1 @ 4ohms amplifier...is there a way to do this...i tought it would be something like this...2 in series(+-+- 8 ohms) and parallel to the third one, which would give about 5.6 ohms...is this about right?

your help would be greatly appreciated

For you second customer, if these are all 4 ohm woofers and you wired two in series then parallel to the third, the nominal impedance would be 2.67 ohms, not 5.6 ohms, but  I would recommend you wire all three of them in series (12 ohms)  or in parallel (1.33 ohms) depending on your amplifier.  If you wired them as you described, the third woofer would see more power than each of the other two.

For your first customer, regardless of the nominal impedance of the SVC woofers and the DVC woofer, I'd recommend replacing the two SVC's with two DVC's or replacing the DVC with a SVC so that each woofer is the same. 

When you use two or more DVC woofers, or  two or more pairs of SVC woofers, you can begin to wire them in a combination of series and parallel. If you do not have either of these combinations of speakers, you should wire all of them in parallel or in series only.

Try this for a quick analogy... Imagine two equal size bathtubs both filled with water. The first has a 4 inch drain hole and the second has an 8 inch drain hole. Both bathtubs are being filled at the same rate, but the one with the 8 inch drain hole is draining faster than the one with the 4 inch drain hole. The maximum rate at which you can fill each at the same rate will be the maximum you can fill the one with the 4 inch drain hole. Now, think of the bathtub with the 8 inch hole as a woofer with a lower impedance (less resistance) and the one with the 4 inch hole as a woofer with a higher impedance (higher resistance) connected in parallel. This would be the same as the way you described connecting the woofers for both of your customers.

thank you 12VOLT appreciate the help.  pretty good analogy too may i add .  is there a calculator available for figuring out these kind of dilemmas? 

if an amp has the specs for subs to be from 2-8 ohms what would happen if i hook them up in the 12 ohm set up...and in the 1.33 ohm set up?  i know that less ohm...more current...hotter amp...harder base, and more ohms...more voltage...less damaga to amp and surroundings (amp rack)...lower base.  but what is the worst that could happen?

i'm also kind of confused about the definition of "bridged" channel...if an amp is bridged (ch 1 and ch 2 to one sub) does this mean that the amp is actually seing this load as half of the sub's impedance?  if i hook a sub to one channel (normal) it would be 4Ù, but if i hook it up to the 2 ch together, would it be 2Ù?   would 2 4Ù sub in series give the amp a 4Ù load?  i was looking at an amp earlier on that left me questioning it's specs... :  40W X 2 @ 4Ù , 100W X 1 @ 4Ù ,  this is with THD=.08%,  and 60W X 2 @  4Ù , 150W X 1 @ 4Ù with THD=.8 %  what more or less does that mean?

your explanation would be greatly appreciated.

thanks in advanced.

You're welcome.There is no need for a calculator to determine if you can use a combination of series and parallel, just simply go by the following: If you use two or more DVC woofers, or  two or more pairs of SVC woofers, you can begin to wire them in a combination of series and parallel. If you do not have either of these combinations of speakers, you should wire all of them in parallel or in series only.  However if you need a calculator to determine the nominal impedance of multiple speakers connected in parallel or series, you can use these here: Parallel & Series Calculators

No harm will come to your amplifier with a 12 ohm load. It simply will not produce as much power as it would at 8 ohms or less. If your amplifier is rated as being stable down to 2 ohms, then do not run it at 1.33 ohms. This will cause damage if the amplifier does not constantly go into protection.

When you bridge two channels of an amplifier to effectively create one channel, each amplifer channel will see 1/2 of the total load. So if you ran your amplifier bridged with a 4 ohm load, each channel would see 2 ohms. 

The power ratings you are referring to are given for different wiring configurations at different levels of total harmonic distortion. You'll see these multiple ratings with pretty much any amplifier that can be configured to run in multiple modes. There's no mystery to it, for example yours says 40W x 2 @ 4 ohms, 100W x 1 @ 4 ohms.... This means in 2 channel stereo mode with two 4 ohm speakers (or 4 ohm load per channel) the amplifier is rated at 40 watts per channel at .08% total harmonic distortion and in bridged mode with a single 4 ohm speaker (or 4 ohm load) the amplifier is rated at 100 watts at .08% total harmonic distortion.

thank you 12VOLT...you've been very, very helpful!!!!

i apreciated the quickness in the response as well.