pairing 4 ohm speakers with 8 ohm speakers

I did it like your first example. I was told this is series. The parallel may sound better but puts more strain on the receiver. I wanted to get away from that for the fact I was running rears.

Hi Raisedonrock,

Reading between the lines, it sounds like you really love music and you're trying to figure out the best way to "plow with the horses you've got". I respect that.

If I understand correctly, your stacked Advents are currently wired in series for a 16-ohm load, and you want to drive a pair of 4-ohm Ohm Model L speakers also. Is that correct?

16 ohms in parallel with 4 ohms = 3.2 ohms, but a "4 ohm speaker" may have an impedance curve that dips down well below 4 ohms. If you have a fairly beefy receiver that is rated for 4 ohms (very few are rated for less than that), AND you are careful not to push it to the point where the output stage overheats or audibly distorts, you should be fine. But approach with caution.

The power distribution to the speakers will not be so good: Roughly 80% of your wattage will go to the Ohms, and roughly 20% to the Advents, so the Advents really won't be contributing all that much. Just so you know.

Let's look at the other possibilities. If you hook up the Ohms in series with the Advents for a 20-ohm load, their respective impedance curves will modulate one another's frequency response, which is a roll of the dice. The power distribution will be reversed (80% shared by the two Advents and 20% to the Ohms), which is better, but now your receiver will voltage-limit and clip at less than half its rated power into that 20-ohm load.

As long as we're rolling the sonic dice, you might want to consider this third possible configuration: Wire the stacked Advents in parallel for a 4-ohm load, and then wire one of the Ohms in series with each paralleled pair of Advents. The net result will be an 8-ohm load, so your receiver will be happy, and the power distribution will be 50% to the Ohms and 50% shared by stack of Advents. I make no promises about how this will sound, but it might sound good, and imo this is the best configuration from the standpoint of your receiver's health, your speakers' health, and getting as much SPL as you safely can.

May the audio gods smile on you in your quest.

Duke

Advice sought:

For surround and HT, I'm using a small KEF Reference 102 as the center speaker with a pair of large 107/2s with surprisingly good results. I have a spare 102 and wonder about using both 102s to fill in the center. The amp is a Proceed HPA-3 (Mark Levinson in an industrial case) with 500 watts per channel into 4 ohms. The KEFs are 4 ohm speakers. I listen at low to moderate levels, and the speakers are set to small and crossed at 80 Hz to a pair of Velodyne HGS-15s through an SMS-1 bass manager.

The reason for the center channel is surround DSD from a Sony XA5400ES. For stereo, I use the 107/2s full range without subs.

db