[Chuck[_11_]]

On Tue, 5 Jun 2018 08:00:04 -0000 (UTC), Matt Faunce
wrote:

geoff wrote:
On 5/06/2018 4:02 PM, Matt Faunce wrote:
Why is there no gain control on the Adcom GFA-535?

I've used it in between my computer (iMac) and my speakers, and controlling
the gain from the computer works, but there's always a noticeable hiss.
Wouldn't it be better to have the output of my computer much higher and
attenuate the output of the Adcom?

No. Sounds like the computer output has a much higher output level that
the Adcom's max input level. Set you computer output level on max and
get a passive volume control, adjusting the level down for max Adcom
output. That will be the best background hiss level you can achieve
using the computer's line output. Or get a better computer, or better
audio D-A interface.


Similarly, I've seen many reviews of powered speakers where the reviewers
complain that there's a noticeable hiss that can't be attenuated. Why are
they designed like that?


That sounds like artifacts from a crappy implementation of a Class-D
poweramp section. Or poor power supply, or both.

If a powered speaker has a hiss that can be heard more than 30cm ( a
foot ) away, it is a heap of junk. I have some cheap-and-nasty 30W
powered speakers beside by computer monitor and can't hear hiss unless I
put my ear within a few inches.

geoff


If I remember correctly, the Adcom caused hissing even when nothing was
plugged into its input. Tomorrow I'll hook it up again and check that.

Unless you are running Klipsch Horns, the GFA-535 should be pretty
quiet with no input. They were so reliable, we used them in
professional installations where their failure rate was almost nil.