Zyx Universe. O.24 mv vs .48 mv with low eff spkrs

Hi all:

The reasons why a designer may want to make low-efficiency speakers is usually because he needs to make a lot of bass from a small enclosure, or is striving for a very flat frequency response, and is using the crossover to burn off (correct) the resonant areas of the speaker drivers.

Also, maximizing the signal-noise ratio of an audio system requires that the first component in the signal chain has the most signal gain, and each following component has a lesser amount of gain. This is because each component amplifies the noise of the earlier components along with the signal, and the higher the gain of the following components, the more the noise and hum and buzz of the earlier components will be amplified.

Since speaker efficiency is also a kind of gain, using a low efficiency speaker makes sense if the overall goal is low noise. Conversely, super-high efficiency speakers (the maximum that I have ever encountered was 116dB) can take a very long time to get right, and require ultra-meticulous choosing of all of the amplification components.

I am not trying to imply that lower speaker efficiency is better than high efficiency, but rather than each is a tool, with its unique advantages and disadvantages. Either path involves trade-offs of some kind.

Incidentally, moving your listening position closer to the speakers is minimal-cost way to gain more listening volume, dynamics and resolution (since air is an effective filter).

Regarding the Universe, typically (but not always) the suspension is secured by a couple of tiny grub-screws inside a metal tunnel, which allows it to be moved fore and aft (together with the cantilever and coils). Pushing the suspension deeper into the cartridge body firms up the compliance by compressing the damper discs more, while pulling the suspension out more loosens up the compliance by compressing the dampers less. IOW, if no components have been damaged by the punishment inflicted by Tom's faulty tonearm bearings, it may be possible to correct the cartridge suspension through a readjustment only - without replacing any internal components. And if no component replacements are required, it could be that ZYX is willing to do the readjustment work for free, or for a nominal fee.

No doubt that ZYX understands their own designs far better than a third party retipper who will not have access to any of the correct replacement parts, nor the detailed documentation that describes how the cartridge needs to be built and repaired, nor the knowledge why it was designed the way that it was designed.

If I were Audiotomb, I'd describe the situation to Mehran and see what ZYX's reply is. It is free to ask.

kind regards, jonathan

Audiotomb, there should be no issue if the volume knob is near the end or all the way up. Usually, all that a volume control does is attenuate the strength of the incoming signal, which the preamp circuit then amplifies by a fixed amount of gain. The only concern with the preamp circuitry should be the level of the signal input, the fixed (maximum) gain of the preamp, and the preamp's maximum output level.

If the signal going into the input jacks is 6V and you use the volume to reduce the input level to 1/10 (0.6V), or if the signal going into the input jacks is 1.2V and you use the volume to reduce the input level to 1/2 (0.6V), both are the same thing to the preamp circuitry. Whatever the input signal level ends up at, the preamp circuit will amplify that by its fixed (maximum) gain, which does not change with volume position.

I know that many audiophiles show a psychological adversion to having the volume turned all the way up, but as long as the preamp output isn't clipping or distorting, the physical position of the volume is a needless worry.

kind regards, jonathan

PS. There may be one or two unique preamps (such as Ayre's KX-R) where the volume does alter the internal gain, but such designs are quite rare.