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Amplifier design parameters required for a good match for high (16+) ohm speakers?

Though I have a reasonable understanding of, or at least am satisfied with, the requirements for an amplifier asked to drive low impedance speakers, I am wondering about specific design parameters that might need be considered when mating an amplifier to high impedance ones. Asked another way: Are there specs that one should seek out when searching for an amplifier to be mated to such speakers?
mesch

Showing 5 responses by atmasphere

atmasphere's avatar
atmasphere
11,574 posts
 
Forgot to add that the manufactures rated sensitivity was based on 1 watt, not 2.83V.

@mesch
In that case 'sensitivity' is not the right word- 'efficiency' is.
IME monostrapping the ST-70 is easy and works quite well.
atmasphere's avatar
atmasphere
11,574 posts
 
The Model One should be very nice with the ST-70. They rate the sensitivity at 92 dB if memory serves; if that is actually sensitivity, the speaker is 95dB 1 watt/1 meter, which will mean the ST-70 has adequate power. If the amp has not been used much, it will need some break-in time during which is will become more lucid.

By mono mode, do you mean monostrapped?
atmasphere's avatar
atmasphere
11,574 posts
 
Ralph, I am using the 16ohm output with the Contrasts, which are rated at 16ohms. I am not sure about actual impedance within the bass frequencies.
Which model?
atmasphere's avatar
atmasphere
11,574 posts
 
Ralph said it was in the best condition of amy he has seen for that time. It was factory manufactured, not put together as a kit. I own a original owners/instruction manual for the kit version so following it, I could likely replace the power supply caps myself if I feel the need.
If it came though here, then we replaced the filter caps. The ones installed allow the 5AR4 to be used, but do have a bit more capacity than stock. We also replaced the bias supply filter caps and rectifiers and probably the coupling capacitors too- the amp was set up to be reliable.
atmasphere's avatar
atmasphere
11,574 posts
 
I guess then, when considering an amplifiers rating into an 8ohm load, one should half that rating into a 16ohm load as a way of assessing that amplifiers ability to provide enough power for a particular circumstance.  
I always found that the ST-70 played better bass if it was possible to use the 16 ohm tap. This is assuming of course that the speaker was at least 16 ohms in the bass region!

The power rating of the amp actually goes up a watt or two as the output transformer is more efficient when used on a 16 ohm load.
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