 -"It
gets loud too soon" |
| You
might have too much gain, so Pre-Attenuation may be required. |
| With Goldpoint stepped attenuators,
normal listening levels are typically when the knob position is between
9 o'clock and 2 o'clock. But if you have high output level signal source
equipment (such as CD players), high gain power amplifiers, and/or very
efficient speakers, a "regular" stepped attenuator may not provide enough
attenuation for you, and you may experience the following: |
| 1) |
The
sound level is too high when turning the knob up only a few clicks - (8
o'clock, for example). |
| 2) |
Turning
the knob up past 12 o'clock makes the sound level higher than you would
ever want it to be. |
|
If either of the above conditions
exist, a good solution is to install a pre-attenuation circuit.
(Two resistors, Rp1
and
Rp2,
as shown below, are added to each channel.) |
Adding pre-attenuation allows
you to turn the stepped attenuator knob up higher (which increases the
number of usable steps on the stepped attenuator). In these cases, adding
about 20dB in front of the stepped attenuator is about right. (See
the charts below for sample resistor values which result in known attenuation
amounts -
for use with known stepped
attenuator values.) |
|
|
| The following tables show
the amount of additional attenuation provided by different Rp1
and
Rp2
combinations. Determine your stepped attenuator value and then refer to
the appropriate chart below to select Rp1
and
Rp2
values.
Usually, about 20dB is a good amount to try first. |
You might use inexpensive
resistors to find the correct amount of attenuation for your system,
and then buy exotic ones
for the final installation. |
A Goldpoint customer shows his installation, installing the resistors directly onto the stepped attenuator:
Photo attached of a 15dB pre-attenuation circuit. ...added a short
Teflon sleeve between R2 and the GND connection just to be 100% sure it
didn't touch the Out.
...used IRC RC55 resistors at 0.1% tolerance... |
|
|
