[AudioCats]

They are from different era, so is the ESP9 a major improvement over the ESP7? The search result only indicates the ESP7 and ESP6 are about the same, just different energizer locations. No word about ESP7 vs. ESP9.......

by the way, what is the stator voltage (normal listening volume) of the ESP7 or ESP9? and bias voltage?

Thanks for any info

 

[spritzer]

The ESP9 is better but I've never spent enough time with them to do any extended comparisons. When I recable the 9's I can drive them off any Stax amp and also have them functioning like Koss intended the same as I did with the ESP6. Then I'll write a mini review but it's not happening any time soon because the Lambda comparison is taking up most of my free time.

Measuring the bias is on my to-do-list but it's in the 300-400v range and the driver voltage is in the same region.

 

[AudioCats]

Thanks!

so I assume the ESP.9 also have different drivers (while the ESP.6 and ESP.7 use the same driver) ?

 

[spritzer]

Quote:

Originally Posted by AudioCats /img/forum/go_quote.gif Thanks! so I assume the ESP.9 also have different drivers (while the ESP.6 and ESP.7 use the same driver) ?

They look very similar but that doesn't mean anything in the electrostatic world. a small (0.1mm) difference can alter the sound completely. The housing is also a big factor in the sound. The ESP9's are also much more complicated then the older brothers with a boat load of extra circuitry. Koss didn't drive them like a full dipole so a small adjustment in the driving principle will alter the sound.