Scott amp update/speaker question

The manual that covers Yamaha NS10, NS15, NS18, NS20, NS30, NS20A and NS30A does not give a sensitivity rating. My guess is they are very efficient. The impedance is 8 ohms and maximum continuos power is 30 watts.

I had excellent results running Living Voice Auditoriums with a Scott LK-150. I also had excellent results with a Sherwood S-5000 on the same speakers.

It's probably NOT the 'efficiency'. Or any sensitive speaker would do.

Rather, it is the phase / frequency relationship which defines the 'goodness' of load. high phase angles will suck an amp dry or reveal an amp which is just good into resistive loads without reference to a 'real' reactive load.

I'd suspect the Yamaha's of being a benign load.

If you had trouble finding just the sensitivity, best of luck with phase.

My original reason for asking, which I probably should have mentioned in the first place - the tech that worked on the amp said I should have speakers that had an efficiency of at least 98 db, but I don't understand what that expression means. Enlightenment?

Unless you want to replace the Yamaha speakers, I wouldn't worry too much.

Efficiency and sensitivity are 2 different things and I'm not up to speed on the technical differences. The number you want is sensitivity, though. Efficiency would be expressed as a percentage....%age.

Personally, I think that phase data....the Inductance or Capacitance of the speaker at different frequencies is more important than a single 'sensitivity' number. This is reactance and the higher the value at any given frequency, the more power is unavailable to the load to do work. What this measures is if the voltage peak and current peak in the waveform are 'in sync'.

If you are curious about this, Google 'Power Factor' for more information. Just Skim the Wiki article for the general idea and look at the illustrations.

Tube amps are a little funny about speaker loads and when SS 'took over', a different kind of speaker came with it.

If it plays loud enough for you, in the space the system is used in and doesn't distort or run out of power, you are probably OK. You could have hi sensitivity speakers, just buying on that number, and have a worse load for your amp.

http://www.stereophile.com/content/totem-dreamcatcher-loudspeaker-measurements

Look at the data from the link. Figure out what you can and post back::

Having just bought a pair of NS-15 here in Switzerland and looking around for more information on those I came across your thread and the NS-serie of Ymaha speakers and found the following link which might serve you

http://audio-heritage.jp/YAMAHA/speaker/ns-30a.html
stating for NS-30A and NS-30B

50Hz～20000Hz
200Hz、6000Hz（6、12dB/oct）
8Ω
103dB/W
30W

NS-10's were used a lot in recording studios as near-field monitors. Your 30T's may be similar in design. The NS-10's tended to be a bit bright on the top and rather revealing through the midrange. This however is working in your favor with the Scott Amp which might be a bit soft on top. You still get the advantage of the midrange while balancing out the top end. If the efficiency is the same as above, i.e. 103dB/1 watt/1 meter that's a great fit. Sensitivity is rated at 1w/1m which mean the 30T's are putting out 103dB when fed 1 watt of power at a distance of 1 meter. Very efficient speakers as the average is usually around 86-88dB 1w/1m. The only issue you may have would be background noise.