Hissing speakers even without a source hooked on amp

[alestaa]

I have 2 triangle zephyrs which are driven by pre-amp + amp by fossi audio which produce a slight hiss even without a source hooked on the amps. Also volume control doesn't make any difference. Any advice please?

 

[puppet]

pre amp gain set too high? If not, maybe get a hold of Fosi.

 

[Osvaldo de Banfield]

It may be the normal noise in any electronic device.

 

[wiseoldtech]

I have 2 triangle zephyrs which are driven by pre-amp + amp by fossi audio which produce a slight hiss even without a source hooked on the amps. Also volume control doesn't make any difference. Any advice please?

A proper test is to SHORT the input to an amp, otherwise the amp can produce more 'noise' with its inputs left Wide Open.

 

[rayma]

Insert shorting plugs into amplifier inputs.
Is the hiss gone? If not, it's in the amps.
If so, it's in the preamp line stage.

 

[wiseoldtech]

Insert shorting plugs into amplifier inputs.
Is the hiss gone? If not, it's in the amps.
If so, it's in the preamp line stage.

Fossi's a china brand...... go figure.

 

[Moondog55]

I have a small Fosi amp here driving my computer sub. Dead quiet when switched on but not actively driving a load.
Runs out of ooomph early but when driven normally they are good value for money.

 

[vacuphile]

Fossi's a china brand...... go figure.

So is Topping, which makes incredible stuff. It doesnt reflect well to figure stuff on the basis of preconceptions.

 

[wiseoldtech]

So is Topping, which makes incredible stuff. It doesnt reflect well to figure stuff on the basis of preconceptions.

Preconceptions?
Please!
I've worked at a service bench for 4+ decades and saw what was being brought in for repairs.
And what I saw not some preconceptions.

 

[stokessd]

Japan used to make crappy stuff and had the same notions as chinese stuff now. Japanese stuff was crappy and then it wasn't, then it got very good (see what the japanese car market did the the big three). China is turning the same corner, but there doesn't seem to be the same universal push for excellence that there was in Japan.

Sheldon

 

[Milsdrewbulch]

I have a small Fosi amp here driving my computer sub. Dead quiet when switched on but not actively driving a load.

You're very unlikely to hear thermal noise from a crummy Chinese line stage from a sub. The audible part of the noise spectrum is filtered out by the low pass.

 

[Moondog55]

What line stage?
The soundcard?
Even using it full spectrum diving the main 2-Way there was no noise.
It's no Bryston or Rotel but a lot better than the usual 10000W PMPO output of the usual cheap computer speakers.
It's not Chinese design or engineering that is the problem perhaps but the "near enough good enough" quality control'
But you get what you pay for in most instances I guess.

 

[wiseoldtech]

You're very unlikely to hear thermal noise from a crummy Chinese line stage from a sub. The audible part of the noise spectrum is filtered out by the low pass.

I was thinking the same thing!