Should I use the 4-ohm or the 8-ohm taps?

[ScottK]

Hello,

I picked up a used pair of Heresy II's on eBay about two months ago. All of the literature that I can find pertaining to this model states that it is an 8ohm speaker. But when I unpacked this pair, one of the first things that I noticed is that on the back of each cabinet it says "nominal impedance 4 ohms."

So, here's the question. I am driving these with a McIntosh 2505 (250 with meters) which has taps for 4, 8 and 16 ohm speakers. Logically, they should be wired to the 4 ohm screws, but they sound much better on the 8 ohm leads. Better dynamics and they play louder at the same position on the volume control.

Will I damage the speakers, or the amp, by using the 8 ohm taps?

Were all early Heresy II's (mine have a copyright date of 1986) 4 ohm, or are mine an anomaly?

TIA.

-Scott

[Deang]

The ears don't lie.

8 ohm taps for those -- definitely.

Those must have been made on April 1st.

[leok]

If, as you spend more time listening, you notice resonances, or peaks at various frequencies, you might again try the 4 Ohm tap. It provides better damping and may smooth the peaks, and extend the highs and lows. Lower acoustic power at a given volume setting is more likely to be good than bad in that, since, in the end, you still have more than enough power, the signal to noise ratio improves.

leok

[Audible Nectar]

Leok has it right. I read on the audioreview.com site about the Mc250 amplifier; in it the owner (the brother of Jim Tidwell - Jim is a member here) discusses using the 4 ohm taps on the Mac to connect to his Cornwalls. I tried this, and while the amplifier doesn't play as loud as it does on the 8 ohm taps given the same position on the gains, I do prefer the sound on the 4 ohm taps - it seems more "under control". I also like the fact that the volume adjustment is easier to set for conversational volume listening, since the volume from the 8 ohm taps seems to "run away" from me very quickly - IOW, more "degrees" of adjustment of volume on the 4 ohm taps. The amp is plenty loud enough as it is - it sounds excellent as I turn it up, and it invites me to turn it up more!! Also, the amp runs cooler using the 4 ohm taps - it barely gets lukewarm.

I find the Mc250 to be quite tubelike, and an excellent match for the Cornwalls.

[Deang]

It would be nice if Klipsch made the impedance curves public.

Think I'll try those 4 ohm taps on the Scott and see what the Cornwalls do.

Craig -- don't say a word.

[Jim Cornell]

My mcintosh 2120 was half the output on the 4-Ohm output! I used the 8 Ohm, no problems!

Jim

[jt1stcav]

As dndphishin already stated, my brother used the 4 ohm taps on his MC250 when he had our dad's Cornwalls. When I traded my bro my Maggies for the Cornwalls, I bought my own MC250 and connected the Cornwalls to the 8 ohm taps. It definately could play louder, but the amp does get alot hotter as well. So I too reconnected the Cornwalls to the 4 ohm taps, and even though I don't hear that much of an improvement to my ears, it is there nonetheless (somewhat smoother in the midrange from what I can tell). I can still crank up the gains to near "live" levels, and the amp does stay cooler, no joke!

Works for me!

[j-malotky]

I must agree with the others here in recomending the 4 Ohm tap for your 4 Ohm Heresys.

McIntosh amps run a bit diferently than the SET amps most of the others use here. The dampening factor of the amps and the autoformers of the older MC amps can not guage the load of the speakers and rely on your setting it to the correct tap.

Give them a closer listen on the 4 Ohm tap. I would bet when you match the volume and listen closely, the 4 Ohm will have better detail, once the dampening factor is running properly.

JM

[jt1stcav]

Scott brings up a good point...were there Heresy II loudspeakers that are 4 ohms instead of 8? I always assumed they were/still are 8 ohms.

[j-malotky]

I have seen both Heresys and Fortes at 4 Ohms. In fact, my Forte 1's I have as side speakers are 4 ohm.

If the plate on the back of the Speaker where you connect your speaker wire says 4 OHM. It is 4 Ohms.

JM

[jt1stcav]

Okay, got that. So then, what's the advantage to changing the Heresy from 8 ohms down to 4 ohms? Just to be able to handle more power from a SS amp at a 4 ohm load? Sorry for the stupid questions, but I really don't know...

[Audible Nectar]

Bumpity.....

[Deang]

"So then, what's the advantage to changing the Heresy from 8 ohms down to 4 ohms? Just to be able to handle more power from a SS amp at a 4 ohm load?"

I don't understand at all how this works with solid state, since solid state works with current as opposed to voltage. I have no idea why a solid state amp would have different taps. Out of my realm. The only thing I know and believe is that the appropriate tap is dictated by the lowest point in the impedance curve.

[Parrot]

I don't know about the impedance of Heresies, but with a Klipschorn, according to the review in AUDIO magazine, the range goes from 4.5 ohms at 55 Hz all the way to 42.3 ohms at 2,155 Hz. So keep in mind that just because a speaker is *nominally* 8 ohms, that doesn't mean it stays at 8 ohms over the entire frequency range.

I have ALK networks on my Khorns and center Belle, and with that crossover design they provide a constant impedance that stays between 4 ohms and about 9 ohms. I have mine connected to the 4 ohm speaker connections on my amps, since most of the power is in the lower frequencies, and the woofer is 4 ohms.

Paul W. Klipsch suggested hooking his speakers to the 8 ohms connections on your amps, but that would not apply when the back of the speaker indicates 4 ohms is better. So go with 8 all the time unless something else is indicated, like in this particular case.