Idea for a dedicated Rhodes preamp, need help !

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PermO

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I understand the frequency roll off is the result of phase cancelation.

Playing with the calculator was very insightfull seeing the phase shifting starting much higher up in the frequency band before the frequency roll off starts to have an effect.
If I build one unit, and I have the choice of grabbing this capacitor from the drawer or the other one, I pick the oversized one that will have less of an effect compared to the smaller one.

If I had to produce +100.000 units and make a profit on them, my choice would probably be different.

[sarcasm]
Why is the high-z instrument input on my RME FF800 so noisy ? and why does it sound like crap ? why do I as a hobbyist have to figure it all out myself and build my own to get a proper instrument input ?
That is what the RME engineering team is supposed to do.... not me !
[sarcasm]

I love GDIY ! :cool:

As far as the human sensory system goes, I'm only an expert on my own sensory system, I don't know what other people are seeing, hearing or feeling, it can sometimes be a bit of a wild guess, but one thing is sure, it does not always line up with mine...
 

abbey road d enfer

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I understand the frequency roll off is the result of phase cancelation.
No you don't.
Phase cancellation is a quite different matter. It happens when a single source travels through two (or more) different paths that have different propagation times. As a result some frequencies arrive out-of-phase, which results in partial or total cancellation, and other frequencies arrive in-phase and create peaks. That's the well-known phaser effect.
As far as the human sensory system goes, I'm only an expert on my own sensory system, I don't know what other people are seeing, hearing or feeling, it can sometimes be a bit of a wild guess, but one thing is sure, it does not always line up with mine...
One needs to be humble.
Many people think they have extraordinary sensory powers; they end up being audio gurus or audiophools (which is worse, I don't know...).
I'm not saying it's your case, but it's quite easy to fool oneself.
I learned to be humble reading the works of Zwicker a,d Fastl.
 

PermO

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We did a little testing.... it's pretty good.

Frequency responce, flat, from 1Hz to aprox 450KHz
Noisefloor of the RME FF800 sits at -110dB, we need a better interface to get acurate noise figures from the proto pre, when we removed the proto pre from the FF800 we were looking at the exact same noise spectrum, so yeah it's probably -110dB or lower.
With 1V input at the highest gain setting the sinewave started to distort (clip) a little bit, I don't think distortion at useable gain setting is an issue, this thing will drive anything... hard, without clipping.
With the transformer the bandwith is limited to 45 KHz and there's a bit of ringing.

Played some bass on BIG speakers, compared to his API style pre DI input... again, the proto pre is the clear winner, the other pre was missing the lowest low end and the top of the top end, and when you switch back to the proto pre the other pre sounds flat like a piece of cardboard.

This is a keeper.
 

PermO

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As it's all about the music.... here's some sounds;


Bass, guitar and Rhodes all recorded with proto pre into AD, no further treatment, no fx, bone dry, just balanced and panned with the midi drummachine on analog mixer.
 
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