4Ohm or 8Ohm for open-baffle Home Theater build?

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Fmstrat

Member
Joined 2020
#1
Hi all,


This is a follow-up to my Open Baffle question thread, but more about speaker selection to pair with my amp.


I'm evaluating the RSS265HF-8 or RSS265HO-44 but I'm not sure which to choose between 4Ohm or 8Ohm. Here are the main specs for the speakers:

  • RSS265HF-8
    • 8Ohm
    • 84.2dB Sensitivity
    • 24.9Hz Fs
    • 14.33mm Xmax
  • RSS265HO-44
    • 4Ohm
    • 90.5dB Sensitivity
    • 27.6Hz Fs
    • 13.25mm Xmax
And my amp is an Adcom GFA-555 II:

  • 600 watts into 8 Ω bridged from 20 - 20,000 Hz at less than 0.04% THD
  • 850 watts into 4 Ω bridged from 20 - 20,000 Hz at less than 0.09% THD
What would be better in my environment? I remember from car audio days that I should stick with 4Ohm, but I'm not sure for this.


Thanks in advance.
 
#2
Use low-Z in car because you only have 12V DC supply. At home you have 120 or 240 AC and transformers. (Yes, we jack-up car DC but it is a drag.)

The -44 is dual 4 Ohm coils. So it interfaces as 2 ohms or 4 ohms. And it sure will not swallow the 600-800 Watts available from that amp.

And are you the one trying an open baffle right behind your head, for a small pocket of intense bass without disturbing others? How much power can you need?? (I just don't know.)
 
#3
PRR said:
Use low-Z in car because you only have 12V DC supply. At home you have 120 or 240 AC and transformers. (Yes, we jack-up car DC but it is a drag.)

The -44 is dual 4 Ohm coils. So it interfaces as 2 ohms or 4 ohms. And it sure will not swallow the 600-800 Watts available from that amp.

And are you the one trying an open baffle right behind your head, for a small pocket of intense bass without disturbing others? How much power can you need?? (I just don't know.)
Click to expand...


Well, the amp is one I've had forever, so I'm sure I don't actually need that level of power, however Open Baffle does require more than normal.


And yes, I'm the one doing that. As for the -44, I did not even realize it was DVC, thanks! I'm not sure that answers my question on 8 ohm vs 4 ohm, though. The 8 ohm option seems to have a better profile for what I'm doing, but I'm just not sure if I'm missing some key piece of information about choosing 4 vs 8 in this scenario.
 
#4
PRR said:
Use low-Z in car because you only have 12V DC supply. At home you have 120 or 240 AC and transformers. (Yes, we jack-up car DC but it is a drag.)

The -44 is dual 4 Ohm coils. So it interfaces as 2 ohms or 4 ohms. And it sure will not swallow the 600-800 Watts available from that amp.

And are you the one trying an open baffle right behind your head, for a small pocket of intense bass without disturbing others? How much power can you need?? (I just don't know.)
Click to expand...

If it's dual 4R, it's either 2R in parallel or 8R in series, no?
 
#6
kodabmx said:
If it's dual 4R, it's either 2R in parallel or 8R in series, no?
Click to expand...


Oh good point, so I guess the only thing I'd really get out of this is more volume via more power. However, I'm pretty sure that's not something I'm going to need. Especially with the RSS265HF-8 at 350W RMS (the RSS265HO-44 is 600W RMS).



kodabmx said:
Not sure if you've looked at JL?

This might fit your needs. 10TW3-D4 - Car Audio - Subwoofer Drivers - TW3 - JL Audio
Click to expand...


I used to own a 12W3 and a 10W3 actually. As they are more optimized for car audio, I'm not sure what the benefit would be. The 10TW3-D4 has a lower wattage and higher Fs than the Dayton options. The low sensitivity is nice, but not necessarily required to be that low for the in-home design (I don't think). Not to mention it's more than twice the price of the others.
 
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