Caiman passive output mod revealed

[gr0001]

I am using a Behringer SRC 2496 for upsampling the signal to 24/96 before sending it to my Caiman. The differences I heard with upsampling were greater separation between instruments, greater depth and a more focused image. In some recordings the differences are much more obvious than others. I would say that it is worth trying. I also did upsampling via foobar but the results were worse than the original 16/44 track...

I also have a question regarding the passive mod. If I remove the opamp board and put the capacitors in, does this make both variable and fixed output passive or just only the variable one??

Thanks!

[Gazjam]

I am using a Behringer SRC 2496 for upsampling the signal to 24/96 before sending it to my Caiman. The differences I heard with upsampling were greater separation between instruments, greater depth and a more focused image. In some recordings the differences are much more obvious than others. I would say that it is worth trying. I also did upsampling via foobar but the results were worse than the original 16/44 track...

I also have a question regarding the passive mod. If I remove the opamp board and put the capacitors in, does this make both variable and fixed output passive or just only the variable one??

Thanks!

Hi,

in Foobar, which resampler did you use?
I tried a few and found SOX (linear phase) to give the best results.

I also tried R8Brain Pro, and external resampler, gave good results as well.

[Stratmangler]

Just got the Guruplug,finally! Will be fiddling this weekend to see if I can get it running. Don't have a clue about linux though,so should be fun!

I wish you the very best of luck - you might need it.
OTOH if you're following a step by step instal guide from the Slim forum then it might just work.

I'm keeping my fingers and all idle apendages crossed for you mate.

[Reid Malenfant]

As I am new to the world of DIY HiFi electronics I wonder what would be a difference in bass or overall sound quality when compared 1uF cap with 47uF capacitor?

I want to compare it higher values as the sound difference from 1uF and 1.6uF is minor (from this post http://theartofsound.net/forum/showp...&postcount=692)

I know I can insert the caps and hear it for myself, but want to know about theory too.
Thanks

Ok, let me first refer you to this post i made here

Depending on the input impedance of the amplifier you are driving with the passive mod output will determine the -3Db frequency that the bass response of the DAC/Amp combination rolls off. This is due to what is known as capacitive reactance.

This can be calculated with the following formula:-

Xc = 1/2 x pi x f x C in plain english that's Xc (the reactance) = 1 divided by 2 x pi (3.1415926545) x f (frequency) x C (capacitance).

The reactance would be it's resistance at the frequency (f).

You can also calculate the given capacitor you'd need to have a certain reactance at frequency (f) of your choice:-

C = 1/2 x pi x f x Xc

Now all these capacitors on a 50Kohm input impedance will have a turnover frequency (-3Db frequency) of well below 20Hz, so in theory you'd hardly expect them to make much difference. But capacitors & the combined input impedance of the following amp create this low pass filter & it's not just the signal getting attenuated below the cutoff. Way before it gets to -3Db the phase of the waveform (if it's pretty close to the cutoff point) will start to shift in phase with regards to other higher frequencies. If i remember correctly this become noticeable a whole decade above the cutoff point (10 x the cutoff frequency).

Assuming you have a -3Db point of say 5Hz it means that the musical signal will start shifting in phase at 50Hz & it'll be gradually be going more out of phase the lower the reproduced frequency is.

It might not be much of a big deal with a single stage, but in an audio chain there are quite a few stages. If each adds it's own phase shift then things can soon add up & bass can sound rather disjointed because it's well out of phase with the stuff being produced in the midrange which isn't subjected to anywhere near as much phase shifting.

I'm sure there is loads more that could be said, right now it's eluding me though

Hope this helps a tad

[Clive]

It's explained here: http://www.v-cap.com/coupling-capacitor-calculator.php

[Ali Tait]

I wish you the very best of luck - you might need it.
OTOH if you're following a step by step instal guide from the Slim forum then it might just work.

I'm keeping my fingers and all idle apendages crossed for you mate.

Ha! cheers mate.Yes I have the wiki downloaded.Some of it might as well be in Swahili though! Still,nothing ventured,nothing gained...

I can always ask Nick to sort out the mess afterwards.

Anyone live near me with linux knowledge?

[Reid Malenfant]

It's explained here: http://www.v-cap.com/coupling-capacitor-calculator.php

That's handy, however i'd hardly call it an explanation

[Clive]

That's handy, however i'd hardly call it an explanation

I think it's the best way to get to understand the issue, reading the text and playing with the calculators is illuminating. I think it helps understanding for those of us with little technical knowledge (but at least a little too)....at least for those who learn by doing, rather than reading a long technical paper with equations.

[Reid Malenfant]

I know I can insert the caps and hear it for myself, but want to know about theory too.
Thanks

I think it's the best way to get to understand the issue, reading the text and playing with the calculators is illuminating. I think it helps understanding for those of us with little technical knowledge (but at least a little too)....at least for those who learn by doing, rather than reading a long technical paper with equations.

Ok & yes Please note that it was mentioned by RoboCopper that he wanted to know about the "theory". This is why i put up those rather simple equations, not to make things difficult, but to show the theory rather than just the results.

Yes the calculator is a very useful tool indeed, but it doesn't show the equations, it does it all for you. Thus no theory...

Anyway, back to the topic in question

[Clive]

Ok & yes Please note that it was mentioned by RoboCopper that he wanted to know about the "theory". This is why i put up those rather simple equations, not to make things difficult, but to show the theory rather than just the results.

Yes the calculator is a very useful tool indeed, but it doesn't show the equations, it does it all for you. Thus no theory...

Anyway, back to the topic in question

To some people theory is equations, to others it's the conceptual theory. Some people will want equations and some won't so a combination of the v-cap page and your post covers it all!