sceleratus
Previously known as Iamnothim
- Joined
- Mar 31, 2013
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Quote:
Precisely
No hum > Mod > Hum > mod fail
I looked into the attenuator because of the whole differential balanced interface thing and that the amp was designed for a pre-amp and that these decked stepped attenuators are pseudo pre-amps..... That's how I got there.
Step one. get it working again.
An attenuator is basically a potentiometer with steps instead of linear travel. The number of sections needed for a volume control doesn't change just because it's labeled "attenuator" rather than "potentiometer". Hence, for a differential volume control, you'd need an attenuator with four decks.
I used to use an attenuator, but it drove me nuts. If you look at most attenuators, you'll see that to get a reasonable range on a 24-position rotary switch, the first couple of steps are *HUGE*. Like 10 dB or so. In my case, I ended up with a setup where step 3 was so low volume that I could barely hear the music, and step 4 was so loud I couldn't concentrate.
In my preamp, I use a PGA2320. -95.5 dB to +31.5 dB in 0.5 dB steps. You won't find that in a rotary attenuator.
The absolute tolerance of the potentiometer may be 5 %, but really it's the tracking between channels that matter. This will improve with an attenuator. But if it isn't bothering you now, it clearly isn't an issue for you.
An attenuator will not fix the hum. Fix the ground loop before you start thinking about more modifications.
You had an amp that had no hum. Then you modified it and got an amp with hum. Something in the conversion went wrong and caused the hum. Trace it down and fix it. Then you can start talking about modifications.
~Tom
Precisely
No hum > Mod > Hum > mod fail
I looked into the attenuator because of the whole differential balanced interface thing and that the amp was designed for a pre-amp and that these decked stepped attenuators are pseudo pre-amps..... That's how I got there.
Step one. get it working again.