Hi everyone. My first post here.
I was given a set of Altec Lansing FX6021. It's quite old but sounds not bad. I took the mainboard out from the sub to see if it's worth for mod. It uses a TDA7295 to drive sub and 2 TDA7477 for satellite speakers.
One tiny SMD cap caught my attention (See "C" in the attached). This tiny cap is no more than 100pF, I guess, but it connects 4558 to TDA7477. What's its function? Why it doesn't filter out lows & mids?
I was given a set of Altec Lansing FX6021. It's quite old but sounds not bad. I took the mainboard out from the sub to see if it's worth for mod. It uses a TDA7295 to drive sub and 2 TDA7477 for satellite speakers.
One tiny SMD cap caught my attention (See "C" in the attached). This tiny cap is no more than 100pF, I guess, but it connects 4558 to TDA7477. What's its function? Why it doesn't filter out lows & mids?
Attachments
Hi
100pF and the 3K3+22K resistors gives a HP filter with a cutover frequency of 63kHz. That would not just filter away the lows and the mids - but practically everything.
Maybe you should check the value of the C - I would more have expected something closer to 100nF.
Being SMDs that can still be a very small capacitor.
Cheers,
Martin
100pF and the 3K3+22K resistors gives a HP filter with a cutover frequency of 63kHz. That would not just filter away the lows and the mids - but practically everything.
Maybe you should check the value of the C - I would more have expected something closer to 100nF.
Being SMDs that can still be a very small capacitor.
Cheers,
Martin
