burns46824 wrote on Tue, 08 February 2011 01:38 |
I recently noticed that my Radial JDI Duplex has an output impedance of 600 ohms. Most passive direct boxes, however, have an output impedance of 150 ohms. Anyone know why the JDI has such a high output impedance? |
Quote: |
I figure the lower the impedance, the better the signal, right? |
Quote: |
And I've heard that, ideally, the output impedance of the DI should be 1/10 the input impedance of the preamp. Seeing as most preamps have an input impedance of around 1,500 ohms, wouldn't the Radial JDI be a "bad match" for most preamps? |
Geoff Emerick de Fake wrote on Fri, 11 February 2011 05:40 | ||
<snip>.... I reckon almost any synth has an output impedance lower than 20k, but most passive gits and basses tend to be more like 100k (Fenders)-200k (Gibsons), so they will "see" a lower than optimum impedance, and the preamp will see a higher than optimum source impedance. It has been proved times and times again that passive DI boxes, convenient as they are, do not constitue an optimum interface (in terms of electrical performance) between passive instruments and low-Z mic inputs. |
burns46824 wrote on Fri, 11 February 2011 09:16 |
Very interesting. Where on earth did you guys learn the math on all this stuff? I need to "read up." ... |
k jacobson wrote on Fri, 11 February 2011 17:32 |
Guitar amps usually have an input impedance of 1 Mohm or more. Hmm, I notice that Radial's J48 active DI has an input impedance of 220 kohms - so is that not suitable for passive guitars/basses either? |