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6 Ohm speakers and Mac autoformers?
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anton
Active Member
I know I can, but will it sound best? And how much power will I loose?:headscrat
I ran my concertinos for years on the 8hom tap. I believe they are rated at 6 ohms. SF sends you an impendence curve graph with your manual. The curve rises a fair bit in places but rarely drops below 6Ohms. I believe most of the new SF speakers are rated at 4homs and I can confirm that my Auditors do sound best on the 4 ohm tap
Chris
Anton,
The network upgrades I make for Klipsch heritage speakers transform them to a true 6 Ohm load. I have them connected to the 4 Ohm taps on my MC7150. I think most loudspeakers are really not a constant impedance load anyhow. The Klipsch heritage speakers for example are actually 4 to over 30 ohms over the audio range. I suspect other manufacturers will be similar.
Al K.
The network upgrades I make for Klipsch heritage speakers transform them to a true 6 Ohm load. I have them connected to the 4 Ohm taps on my MC7150. I think most loudspeakers are really not a constant impedance load anyhow. The Klipsch heritage speakers for example are actually 4 to over 30 ohms over the audio range. I suspect other manufacturers will be similar.
Al K.
Steve Hoffman
Mac and Roundie TV lover
Take a slightly compressed recording, mono preferred.
I use I FEEL FINE by the Beatles from the PAST MASTERS VOLUME ONE CD. I'm sure everyone has that.
Play the first 40 seconds of the song on the left channel only (the drums and bass channel). Switch back and forth during the music from the 4 to the 8 tap. Which ever has the best tonality and dynamics is the one to use.
Don't use a record that has too much dynamic range or it won't work. Use something like the above. Listen for bass response and ease of sound.
Have fun!
If they only made speakers that would have a straight line impedance curves. They are usually all over the place from as low as 2 ohms all the way up past 25 ohms even though the nominal impedance may say 4,6 or 8 ohms. Play around with the taps and go with what sounds best to you, you are not going to hurt anything.
Guys,
Changing the taps while listing to a musical passage is very deceiving. The higher impedance taps will always sound louder than the lower impedance taps. This will fool you into think the impedance is a better match at the higher impedance tap. This is not so, it's just a higher voltage which will deliver more power at a given impedance even at low levels. The difference is how much total power will be delivered at maximum volume. The output transformer simply converts the speaker impedance to the impedance the amp wants to see to deliver maximum power. There should be no difference in sound quality at normal listening levels.
AL K.
Changing the taps while listing to a musical passage is very deceiving. The higher impedance taps will always sound louder than the lower impedance taps. This will fool you into think the impedance is a better match at the higher impedance tap. This is not so, it's just a higher voltage which will deliver more power at a given impedance even at low levels. The difference is how much total power will be delivered at maximum volume. The output transformer simply converts the speaker impedance to the impedance the amp wants to see to deliver maximum power. There should be no difference in sound quality at normal listening levels.
AL K.
I auditioned a pair of Harbeth 7ES3 at home over the weekend with my MC275 IV. They are rated at 6ohms. There was a dramatic difference in sound quality between the 4 and 8 ohm taps. I was very supprised because my own speakers (Dali Ikon 6) which are also rated at 6ohms, did not seem to differ much, if at all between the two taps. On the 4ohm taps the Harbeths sounded very soft, warm, inarticulate in the bass. On the 8ohm taps they were very detailed and articulate, with well defined bass, but a little lean sounding compare to the 4ohm taps. I didn't switch back and forth while playing music, but turned off the amp and changed taps and then corrected for volume level. However, the difference in sound was so blatently obvious that it could not be attributed to slight volume differences anyway.
ByteWrangler
Active Member
Couldn't you connect a speaker to the 2-Ohm and 8-Ohm taps of the autotransformer to match a 6-Ohm load? Assuming, of course, that you have a 2-Ohm tap.
Victor
Super Member
I don't think that would be wise.
Just pick the 4 or 8 ohm tap, whichever sounds best. As long as the Power Guard lights do not come on often and as long as the amp does not overheat the amp will be fine. If the Power Guard lights do come on or if the amp overheats then use the next lower speaker tap.
My speakers are 4 ohm and I think the 8 ohm tap sounds the best, so that is what I use.
Victor
william.keith
Super Member
Victor, what exactly do you notice that sounds best using the 8 ohm tap? Why wouldn't the 4 ohm tap technically sound better since this is how McIntosh optimized the design of the speaker and amp?
Victor
Super Member
With the speakers on the MC501 8 ohm taps as expected the sound was exactly 3 db louder. After I matched the volume I found I like the 8 ohm taps better. The sound with the 8 ohm taps was a little more detailed and the imaging improved a little also. Usually added detail comes with added harshness but with speakers hooked up to the 8 ohm taps it was smoother. The differences were not major but to get more detail and smoother with the same change really surprised me.
I usually listen at lower volumes (65-75db). I have heard from other people with 4 ohm speakers that when they listen at loud volumes to dynamic music with complex passages they like the sound of the 4 ohm speaker taps better. So listening habits as well as the speakers used could affect which speaker taps sound better, the best thing to do is try both speaker taps and see what sounds best in your system.
Victor
I have experimented with the available taps(MC252) for my NHT VT2.4 towers(6 ohm nominal) and I did not notice any difference in the sound or even what the watt meters were showing. I just use the 4 ohm taps as recommended by, I cannot remember now(Chuck Hinton??)...
Those speakers are rated at 250watts max and the MC252 is more than enough for them. I really push the MC252 and I have never seen the power guard leds light up.
Doug
Those speakers are rated at 250watts max and the MC252 is more than enough for them. I really push the MC252 and I have never seen the power guard leds light up.
Doug