giribaldo Posted March 6, 2004 Share Posted March 6, 2004 Hi, I have a pair of RF-7 that i drive vith a tube amp. I tryed to connect to 4 ohm and to 8 ohm tap of amplifier, i notist that at 4 ohm at same point of knob it sound less louder, with no problem i can turn up again the volume... the matter is i' m not able to say if the sound is better with 4 or 8 hom tap... so before to connect and sconnect a lot of time the speaker i would ask at people that use RF-7 with tube amp what tap use and if possible why you prefer one to another. and if there are tecnical reason to use one or another tap particular with RF-7 are public impedance curve of rf-7...? thanks all Giribaldo Quote Link to comment Share on other sites More sharing options...
leok Posted March 6, 2004 Share Posted March 6, 2004 If you have enough volume using the 4 Ohm tap I recommend using it. 1) loading on the amp's output tubes is lighter resulting in lower distortion. 2) noise floor is lower 3) amp output impedance is lower, reducing speaker/amp interaction. Take a look at page 85 in the stereophile "Special Issue: Multichannel Music" .. just out, now at news stands. Look at Fig 5, 6, 7 along the bottom of the page. Notice that the distortion is lowest using the 4 Ohm tap. Also, on a related topic .. feedback, I suspect that the uptick in distortion at the very low end is due to feedback. However, without feedback, the entire set of curves would be higher, but without the low-end uptick .. just a thought, no proof except KT66 distortion specs. Leo Quote Link to comment Share on other sites More sharing options...
Deang Posted March 6, 2004 Share Posted March 6, 2004 No, I think you're right. I think no feedback amps definitely sound cleaner and more open at the lower volume levels (80db or so and under). Past that point however, the world turns upside down. My QUADs have 26.5db of negative feedback, and when I hit 90db (and beyond) -- it is without question the best sound I have heard to date from a amp/premap. Below that however, I do experience the ever shrinking soundstage effect. Quote Link to comment Share on other sites More sharing options...
giribaldo Posted March 7, 2004 Author Share Posted March 7, 2004 hi, today i tryed a lot on 4 and 8 ohm... with 4 ohm tap - seem to be more bass ... - seem the amp became less hot - yes less noise - more accurate precise the reproduction with 8 ohm tap - more open-fast and more live i think i will do sometime in one way and other in the other way no of the two i prefer on the other beautiful anyway thanks for help :-) Quote Link to comment Share on other sites More sharing options...
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