Hi,
I have made pair of rca interconnect cables with -20.8 dB attenuation. I used 10k in-line and 1k0 as grounding resistor. The amount was just spot on to get more room to move with my volume pot. Now I am just thinking if I lost some of the low frequencies by using a L-pad if it is affecting the impedances too much.
So to speak, if I would like to have -20db of attenuation while keeping original output and input impedance ratio of my pre/power combo appropriate, is L-pad the right choice. Or should it be T-pad or maybe something else? This is a bit new area for me to explore...
My pre/power combo is following:
Prima Luna Prologue 3 preamp, output impedance 2.8 kOhms
Hypex Ucd180Hg poweramp, input impedance 100kOhms.
One option to try of-course, would be just removing the gain resistor from Hypex amp boards. But I am afraid the attenuation wouldn'tbe enough.
I would be very happy if I could get some help with my issue.
Best,
Mikko
Ps.
This is the original post I got my L-pad values from:
I have made pair of rca interconnect cables with -20.8 dB attenuation. I used 10k in-line and 1k0 as grounding resistor. The amount was just spot on to get more room to move with my volume pot. Now I am just thinking if I lost some of the low frequencies by using a L-pad if it is affecting the impedances too much.
So to speak, if I would like to have -20db of attenuation while keeping original output and input impedance ratio of my pre/power combo appropriate, is L-pad the right choice. Or should it be T-pad or maybe something else? This is a bit new area for me to explore...
My pre/power combo is following:
Prima Luna Prologue 3 preamp, output impedance 2.8 kOhms
Hypex Ucd180Hg poweramp, input impedance 100kOhms.
One option to try of-course, would be just removing the gain resistor from Hypex amp boards. But I am afraid the attenuation wouldn'tbe enough.
I would be very happy if I could get some help with my issue.
Best,
Mikko
Ps.
This is the original post I got my L-pad values from:
Hi,
fit the two resistors inside the RCA plug that goes onto the NAD poweramp input. No cable to help avoid the hf rolloff that would ensue due to capacitance between attenuator and input stage.
use a 10k in line and then choose a grounding resistor from the list.
Interconnect core to 10k to RCA centre pin.
and
RCA centre pin to grounding resistor to ground.
grounding resistor
4k7 => -9.9db these low atten give more risk of HF roll off
3k9=>-11db
3k0=> -12.7db
2k0=>-15.6db
1k5=>-17.7db
1k0=>-20.8db
750r=>-23db at this atten HF roll off almost zero @ 20kHz.
should be enough options to get you going.
BTW attenuation = 20 times [inv log (grnd res/10k+grnd res)]
This formula is not accurate because it does not account for the source impedance nor the poweramp input impedance but again it is close enough.