Newbie parellel 3886 speaker impedence question

[2004ex]

I have a single 3886 gainclone connected to a 8 ohm speaker. When converting to parallel by simply adding another identical module (following AN-1192), the sound volume I heard was about the same as before (a little bit disappointed). I guess that each 3886 is seeing a 16 ohm load now. So in order to have the expected higher volume output, one needs to change the 8 ohm speaker to a 4 ohm one as well, otherwise there is no advantage in parallelling? TIA.

[jaudio]

For 8 ohms,why not try a bridged amp? You get double the voltage, not volume,it should sounded louder(3db). You will notice the Difference

[AndrewT]

Hi,
the amplifiers are sending out the same voltage whether in parallel or single mode.
Same voltage and same load = same power = same SPL.
However, each amplifier is only sending out half the current requirement of the load, if the parallel matching is accurately accomplished.

That lower current should result in less stress on the amplifier and the end result should be cleaner sound and fewer protection triggering events.

Paralleling should sound better, even though no louder.

But, there was an assumption hidden in there.
I think the amps when paralleled will put out a tiny fraction more voltage in low volume settings, when pushed hard the improvement in voltage output may no longer be tiny. It could be quite significant, maybe of the order of 1db to 2db depending on how badly the single amplifier performs.

[2004ex]

Originally posted by AndrewT

Same voltage and same load = same power = same SPL.

So the AN-1192 PA100-100W amp is actually 100W only at a 4 ohm load, otherwise same as a single 3886 (~50W) amp at 8 ohm as far as ouput SPL is concerned, except that less heat will be generated at the chips? I am already running them at +/-32V DC rail, and I do not want to buy a new set of 4 ohm (or more sensitive) speakers just for this. Bridging (e.g. BA100-100W) is not convenient in my case as it will require modifying the input polarity and gain feedback circuit that are not part of my pcb. So to get a higher SPL than a single 3886 can provide, I suppose I need to switch to discrete transistor amps such as the P68?

[lgreen]

Seems to me you are making an inapplicable comparison by looking at perceived volume vs. power capability. These have nothing to do with one another. When you made the amp into a parallel amp you made it twice as powerful though it did not seem to play louder with the same input.

Just turn up the volume and it will be able to go louder than the prior version!! If you want it to appear to be louder with the same input you can give it more gain by carefully changing the input/feedback resistors.

[AndrewT]

Hi Lg,
if I have understood correctly, then your message is wrong.