line level output —>>> H9 input

[nickrose]

Hi Geido – I don't see a problem with frequency loss here.

The main potential issues are related to the fact that H9 was designed for a guitar input:

1) The 600K input will be noisier than a 10K input, so you want to give it a reasonable level, but ….

2) The H9 is expecting guitar levels, so you should be careful not to overload it either.

[geido]

nickrose wrote:

Hi Geido – I don’t see a problem with frequency loss here.

The main potential issues are related to the fact that H9 was designed for a guitar input:

1) The 600K input will be noisier than a 10K input, so you want to give it a reasonable level, but ….

2) The H9 is expecting guitar levels, so you should be careful not to overload it either.

 

Hi Nick, thanks for the quick reply.

I had tried to feed another stompbox’s load of 1M ohms (the double of the H9, about 2000 times higher than a line output impedance) with a line level signal and the result was a loss of higher frequencies: the circuit actually works as a low pass filter. SInce then I use the Radial Engeneering stompbox in between (the one mentioned in the original post). Since the line level and the H9 load ratio is 1/1000 (much more than the 1/10 ratio tolerated in the bridging law) I believed to get similar result (high freq. loss).

Best, Geido

[geido]

Hello, my question today concerns the possibility to use the H9 as a digital outboard fx unit in a send/return configuration with a mixer/interface. To do this it is necessary that the load of 600K ohms inputs on the H9 is fed with line level signals (the outputs on the mixer/interface).

Generally, we don’t need  “to match” impedance values. As far as I know, especially with line level signals, our objective is to maximize the voltage transfer between the source and the destination (and minimize the current flow): the bridging law, indeed, states that a low impedance output can feed a higher impedance input, according to a ratio of 1/7 max 1/10. And that’s how line outs and line ins are plugged and work fine. Nevertheless, the impedance of a line input is typically around 10 kΩ and the impedance of a line output is around 600 ohms, whereas the gap with the H9 input impedance (600k ohms) is too wide…

So I am afraid that the load impedance on H9 preamp will not accept a line level output without frequencies loss. The connection likely would require some further gear to manage the impedance bridging, for example a Pro-RMP Studio Re-amper: http://www.radialeng.com/prormp.php

Any hint?

Best, Geido

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