What?

Sorry I mean, pardon?

Your amp is rated up to 4 ohms, you will be safe.

If you bridge to mono one channel is not not used. This is the bit I'm whatting about.

If you bridge to mono one channel is not not used. This is the bit I'm whatting about.

This was the answer I was looking for! I used to the world of Valve/tube guitar amps where if you mismatch the impedance you generally get shafted so I thought it was better to check!

When it bridging to mono does it just switch the other channel off or will it put the full 100 watts into the channel that is being used? Also will running the amp in mono change the output impedance of the amp?

Sorry for all the noob questions - the manual and technically specification with my amp is next to useless!

Thanks Mike

Bridging puts the full 100watts into one channel. Although, really it should bridge 2*100w because you have two amps, one left and one right.

The output impedance of the amp is not what you're thinking about.
Basically the amp ohmage rating is a stability rating, when you run at 16ohm you get lower currents than when you run at 4 ohm. Your amp is 4ohm stable so you can run 4ohm, 8ohm, 16ohm or 40,00000000000,000 ohms... No worries.

Just don't go trying to push a 2ohm car sub without a fire extinguisher or somnat.

michaelwithersone wrote: ..my speaker cabinet loads at 16ohm when wired in stereo...
... if I connect my cabinet in mono then the cabinet impedance drops to 8ohm.

Does not compute. :D How many speakers do you have in your cabinet and how many ohms on each?

16 8 4 2 <- ohms each
--------------------------------
64 32 16 8 : 4 speakers all in series
16 8 4 2 : 4 speakers, 2 series, then those two in parallel
4 2 1 0.5 : 4 speakers all in parallel
32 16 8 4 : 2 speakers in series
8 4 2 1 : 2 speakers in parallel

.. if you have two independent, channels each 16 ohms, on your cabinet I guess that would make scene... If that is the case, then wire them as 8 ohm parallel for double power!

Gecko, I totally understand what you're talking about but I can't hook sense from that table. Lol. :)

For series R = R1 + R2 + R3...
For parallel 1/R = 1/R1 + 1/R2 + 1/R3...
Where R is the total resistance and R1 R2 R3 etc are the individual speaker ohms.

Wait, I just figured your table out. Groups of 4 and 2.
It's late. :P

Table edited for clarity.

Thanks Greener :)

"get shafted"

LOL I love that word.
Shafted.

Along with many other fantastic words.

I think you are confusing two different concepts here.

The first is paralleling of loudspeakers. Wiring two 16 Ohm cabinets in parallel gets you an 8 Ohm pair with the power split between the two. This 8 Ohm load would connect to one channel of the amplifier and the other channel would be left open circuit. This does no damage. However, a better arrangement would be to use one 16 Ohm loudspeaker on each channel and to send the mono signal to both amplifier inputs.

The second is bridge operation of amplifiers. In this configuration, you would wire the loudspeakers in parallel (to get 8 Ohms) and take one loudspeaker wire to the + output of one channel and the other wire to the + output of the other channel. For this to work, either the amplifier must be switchable to bridged mode (channel B invert), or you must feed phase and antiphase drives to the amplifier inputs. This is generally not a problem when the amplifier is being driven from balanced outputs, as a simple XLR pin 2-3 crossover achieves the desired effect.

As to making the bridging the stereo amp to mono, I checked on how to do it to my Rotel. It requires you to change three internal jumpers.

My guess is Mike's amp can't be bridged mono.