How to wire MC 501 for 6 ohm load

[1948epiphone]

I'm thinking about getting Von Schwiekert VR-4jr's. Apparently in bi-wire mode they present a nominal 6 ohm load. Which taps would you use on the 501? Is it safe to experiment or is there a general rule about the autoformers that dictates which tap to use.

 

[jim777]

Try the 4-ohm tap, you won't break anything and it should play loud enough

If you use the 8-ohm tap, it'll be slightly louder but the amp will be working harder.

Have fun!

 

[hassel]

I have Shahinian Diapasons, which are a 6-ohm-load, too. The 8-ohm-tap gives me more power, and much better sound, than the 4-ohm-tap, on my MC402: 600 watts. Chuck Hinton of Mc-support told me this was no problem for the amp. With the 501, you get 750 watts from the 8-ohm-load, when you connect a 6-ohm-load. Hinton said this would not be a problem for the 501, too, as all Mac-amps are constructed with huge reserves.

 

[carlman]

Interesting... so why are the taps even there? Seems like the autoformer could just adjust to whatever load is presented.

I have the MC402 with 4 ohm speakers. I was planning on trying different taps to see if there was any difference... haven't gotten around to it yet, though. On some tube amps I've tried in the past, 4 ohm taps will sound better than 8 on a 4 ohm speaker... but I don't know if this causes any real damage.... especially at sane volumes where you're using 1-50 watts.

-C

 

[jim777]

Interesting... so why are the taps even there?

So that a 4-ohm speaker on the 4-ohm tap and a 8-ohm speaker on the 8-ohm tap looks like the same load to the amplifier. You can try a 8-ohm speaker on a 4-ohm tap. The other way around, the amp will only be working harder.

 

[Victor]

Interesting... so why are the taps even there? Seems like the autoformer could just adjust to whatever load is presented.
-C

The taps each go to a DIFFERENT winding in the autoformer to give you the best match for your speakers. So it is like you get 3 amps for the price of one.

Victor

 

[hassel]

According to tests that Joachim Pfeiffer of the German magazine Audio did during his 20 years of using Mac-amps, you would nearly always get the better sound from the 8-ohm-tap, even with most 4-ohm-speakers. The proof is in the hearing, in my case, it was no slight, but huge difference.

 

[PHC1]

I agree, I hear an audible difference for the better with the 8ohm taps on my 501's.

 

[jim777]

When you use a higher tap, you reduce the damping factor. Probably gives a more "tube-like" sound.