8ohm vs 4ohm on Rogue Integrated

hochpt21

Does it matter greatly what tap I have the Rogue Cronus Magnum 2 running on?

I had it on the 8 ohm tap while running the SDA 2a's and the Epos Epics which are both 4ohm speakers. Sound was fine and power seemed adequate. I've been using it this way for about a month.

Yesterday with the 2a's, after about an hour at moderate volume the Rogue went into protect. So I popped the lid and changed the taps (which was a fairly reasonable PITA) to 4ohm.

I'm assuming this is appropriate, however, if I want to run an 8ohm speaker, do I need to switch it back over to the 8ohm tap?

Thanks,
Paul

displayname

It's not always a clean cut answer, but the general rule is if your amp omh setting is equal to or lower than the speakers you're fine.

4ohm speakers into 8ohm amp = bad
8ohm speakers into 4ohm amp = fine

Again, a general rule, not gospel.

mhardy6647

So -- don't forget that the nominal impedance of most loads is just that... nominal.

Here's the impedance curve of a loudspeaker rated by its manufacturer as "compatible with 8 ohm outputs", for example


https://www.stereophile.com/content/polk-lsiiim703-loudspeaker-measurements
(the impedance trace is the solid line; the phase trace is the dashed line)

Neither Stereophile nor I would call it an 8 ohm speaker -- would you?
And no matter what you'd call it -- what tap would you run it on? Probably the one that sounded better to you

My recommendation would be run whatever speakers you want to run on whichever taps sound better to you.

The only 'harm' that will result could be less power and or higher levels of distortion delivered to the load from a mismatched tap -- there may be little, no, or positive consequences in terms of the sound.

Mike Reeter

FWIW, A call to Rogue when I first purchased the Cronus, explaining that my speakers were a 6 ohm load and wondering which tap to use. Nick replied "whichever sounds best".

I powered the SDA's with the 4 ohm tap, with no problems.

hochpt21

An e-mail reply from Rogue before I ever used the 2a's said that the Cronus was common ground and should work well with the SDA's.

Further, most of the information I could find on the 4ohm vs 8 ohm stated that whatever sounds best is fine. Well then my amp shut down yesterday and I thought, maybe it does matter...at least with this amp/speaker combo.

I'll run it on the 4 ohm and go from there.

Mostly I just don't want to have to get in there and change it back if auditioning a pair of 8ohms.....

Mike Reeter

hochpt21 wrote: »

An e-mail reply from Rogue before I ever used the 2a's said that the Cronus was common ground and should work well with the SDA's.

Further, most of the information I could find on the 4ohm vs 8 ohm stated that whatever sounds best is fine. Well then my amp shut down yesterday and I thought, maybe it does matter...at least with this amp/speaker combo.

I'll run it on the 4 ohm and go from there.

Mostly I just don't want to have to get in there and change it back if auditioning a pair of 8ohms.....

I hear ya, changing those taps from 4 to 8ohm (or visa versa) is a PAIN, especially if you have big hands and big fingers to go along with them

smglbrth

If those are the same 2A's you got from me (via Don) they do run below 4 ohms with the newer crossovers/inductors. 3-3.5 if memory serves...

delkal

mhardy6647 wrote: »

So -- don't forget that the nominal impedance of most loads is just that... nominal.

Here's the impedance curve of a loudspeaker rated by its manufacturer as "compatible with 8 ohm outputs", for example


https://www.stereophile.com/content/polk-lsiiim703-loudspeaker-measurements
(the impedance trace is the solid line; the phase trace is the dashed line)

That part where the impedance drops below 4 and the phase angle drops to -45 is a double whammy. DO NOT Play a 70-90 Hz test tone loudly with these speakers.

I would use the 4 ohm tap.

hochpt21

smglbrth wrote: »

If those are the same 2A's you got from me (via Don) they do run below 4 ohms with the newer crossovers/inductors. 3-3.5 if memory serves...

I was looking back at our original conversations and saw that. I’m finally starting to focus on this system so your baby’s are getting some much needed attention.

hochpt21

Well she’s been humming along on the 4 tap for 2+ hours with no problem now. Filled out the bottom end a bit more.

And then I added a new SVS sealed sub, so the bottom end hath done been solidified.

I came down here to test it a couple hours ago, but I’m kinda just stuck in this chair.

GlennDog

hochpt21 wrote: »

I came down here to test it a couple hours ago, but I’m kinda just stuck in this chair.

With a cold libation in hand . . . In my top 5 things to do. Period.

yyzian

I have the same integrated paired with Harbeth compact 7s which are 6 ohm rated. Connected to 8 ohm taps they went into protection couple of times. On the 4 ohm haven’t had any issues for the past 9+ months

hochpt21

Good to know.

I switched it to the 4ohm tap a couple months ago and no problems since.