4ohm speaker inputs- actually 8 ohms?

[petejt]

The MarkIV has three speaker outputs- one 8 ohm mono output, and two 4 ohm outputs, wired in parallel. I believe that means that each "4 ohm" socket connects to an 8 ohm load (cab).

My Stiletto cab appears to have the same type of speaker inputs- one 8 ohm, and two "4 ohm" inputs.

Does this mean that each input socket is actually an 8 ohm load? I guess I am saying, is the cab theoretically a pair of 8 ohm 2x12 cabs in one enclosure?

Can I connect the 4 ohm outputs of the MarkIV to the 4 ohm inputs of the cab, safely?

 

[MrMarkIII]

Each speaker in the cab is 8 ohms. Each pair (2 x 12) is hooked up in parallel, for 4 ohms total for each pair. Then the pairs are hooked up together in series for a cab total of 8 ohms (4 x 12).
From the Stiletto manual:
"Overall your Stiletto is very impedance friendly and most speaker loads will work great with the exception of slightly shorter power tube life occurring when a mismatch in the low direction (two 4 Ohm cabs - each in a 4 Ohm jack to produce a total load of 2 Ohms) is used for long periods of time."
Yes, you can use two speaker (not guitar) cables, and run from the two 4 ohm outputs on the amp to the four ohm inputs on the cab. It's a safe mis-match, but just barely.
The question, of course, is "Why?"
Those two 4 ohm inputs on the cab are designed for stereo set-ups if I'm not mistaken.

 

[Boogiebabies]

The 4 Ohm tap is wired in series. It is two 4 Ohm taps as it is coming off the OT as 4 Ohm's.
Boogie has always made their speaker cabs with 8 Ohm outputs, so two would be used in the 4 Ohm taps
and one in the 8 Ohm tap, or one in the 4 Ohm tap as a safe mismatch. If you ran two 4 Ohm cabs in the two 4 Ohm taps it would be 2 Ohms and on
the verge of a meltdown.

 

[Mark Fore]

When in doubt, read the manual or back of the amp. Mesa actually prints on the amp by the jacks, "Use two 4 ohm jacks for two 8 ohm cabs" or something to that effect.

 

[thunda1216]

hmmmmmmm. now I'm really confused. My Heartbreaker has one 16 ohm output jack, two 8 ohm output jacks and two 4 ohm outout jacks.

I thought I could run one 16 ohm cab, or two four or eight ohm cabs.

The manual states, "...can accommodate a wide variety of extension cabinets and SPEAKER impedance loads by using some combination of the five available SPEAKER output jacks that are found as illustrated..."

So, does this mean that I can use one 16 ohm cab and one 4 ohm cab? One 8 and one 4 ohm cab? Two four ohm cabs? I need a drink!

ty

 

[MrMarkIII]

hmmmmmmm. now I'm really confused. My Heartbreaker has one 16 ohm output jack, two 8 ohm output jacks and two 4 ohm outout jacks.

I thought I could run one 16 ohm cab, or two four or eight ohm cabs.

The manual states, "...can accommodate a wide variety of extension cabinets and SPEAKER impedance loads by using some combination of the five available SPEAKER output jacks that are found as illustrated..."

So, does this mean that I can use one 16 ohm cab and one 4 ohm cab? One 8 and one 4 ohm cab? Two four ohm cabs? I need a drink!

ty

One 16 ohm cab ----> 16 ohm speaker jack.
Two 16 ohm cabs ---> One each into the two 8 ohm jacks.
Two 8 ohm cabs ----> One each into the two 4 ohm jacks.
Two four ohm cabs, as stated above, is only marginally safe, as the load goes down to 2 ohms. Your tube life will suffer.
Best to stick with 8 or 16 ohm cabs, which are far more common, anyway.

 

[petejt]

Each speaker in the cab is 8 ohms. Each pair (2 x 12) is hooked up in parallel, for 4 ohms total for each pair. Then the pairs are hooked up together in series for a cab total of 8 ohms (4 x 12).
From the Stiletto manual:
"Overall your Stiletto is very impedance friendly and most speaker loads will work great with the exception of slightly shorter power tube life occurring when a mismatch in the low direction (two 4 Ohm cabs - each in a 4 Ohm jack to produce a total load of 2 Ohms) is used for long periods of time."
Yes, you can use two speaker (not guitar) cables, and run from the two 4 ohm outputs on the amp to the four ohm inputs on the cab. It's a safe mis-match, but just barely.
The question, of course, is "Why?"
Those two 4 ohm inputs on the cab are designed for stereo set-ups if I'm not mistaken.

Sorry, it's a confusing setup.


I have two 4x12 cabs, and want to run them w/d/d/w, as if each vertical pair of speakers is a 2x12 cab. Ideally I want to run each pair at 8 ohms.

 

[Stonge]

I am also confused a bit. You guys make it sound like plugging a 4OHM load out to a 4OHM cab is wrong. Is this true?
I have the Stiletto ACE.
4OHM load on amp is plugged into a 4OHM 2x12.
Can I be doing this safely?? If the cab is a 4OHM cab??

 

[Boogiebabies]

A 4 Ohm speaker cab to a 4 Ohm jack is a perfect match. What we are trying to get across is that two 4 Ohm cabinets
equals 2 Ohms when using the two 4 Ohm jacks. That is not a smart mismatch.