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Thread: A/D Converter High Res No high pass

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    A/D Converter High Res No high pass

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    Do they make an affordable A/d converter that doesn't have a hardwired HPF?

    I am looking at these and I know almost everything dose so I am just going to assume this dose too?
    RME ADI-2 Pro FS AD/DA Converter | Sweetwater

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    Quote Originally Posted by Ryan Murphy View Post
    Do they make an affordable A/d converter that doesn't have a hardwired HPF?

    I am looking at these and I know almost everything dose so I am just going to assume this dose too?
    RME ADI-2 Pro FS AD/DA Converter | Sweetwater
    That interface goes down to FIVE Hz! How much lower did you want to go?

    Dave.

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    While I'm no expert on circuit design, most (all?) of the audio circuits I've delved into have DC blocking capacitors at various points out of necessity. I suspect those can't be arbitrarily low.

    What's the point of going below 20Hz?

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    Quote Originally Posted by bouldersoundguy View Post
    While I'm no expert on circuit design, most (all?) of the audio circuits I've delved into have DC blocking capacitors at various points out of necessity. I suspect those can't be arbitrarily low.

    What's the point of going below 20Hz?
    Some 'High End' designs eschew capacitors and use DC servo circuits to keep outputs at 0 volts. I find the claims for better fidelity dubious...the MORE so since these same designers often extol the sonic virtures of transformers! The latter will always introduce more distortion than a well specified electrolytic capacitor.

    Maybe it's a 'snob' thing? Capacitors are cheap, = BAD! Transformers are expensive, especially really good ones, = GOOD.

    I always wonder? Say you have a totally DC coupled path from an AI to a DC servo'ed, DC coupled 200W active monitor and just ONE servo in the chain goes 18 volts ape shit? !!

    I cannot remember the last time I had an electrolytic capacitor short?

    Oh! BTW BSG, there is a church organ with a 16Hz pedal pipe! In Oz somewhere I think.
    Dave.

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    I found this: "There are two instruments that have a full-length 64’stop. The first one is the Midmer-Losh organ at the Atlantic City Convention Center. The second one is the Pogson organ in the Organ Sydney Town Hall."

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    Quote Originally Posted by gecko zzed View Post
    I found this: "There are two instruments that have a full-length 64’stop. The first one is the Midmer-Losh organ at the Atlantic City Convention Center. The second one is the Pogson organ in the Organ Sydney Town Hall."
    Obliged Gekks. Now all OP needs is a mic that can get down there, a sub woofer to do same (would need at least a 1kW amp I think) and a FURKIN big room!

    If instead he wants to record infrasonics, whales say then I suggest the inverse of a Bat Detector. Instrumentation recorders, strain gauge data say, used to use a DC to frequency converter to record to conventional tape. You STILL have to find a suitable primary transducer!

    Dave.

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    Quote Originally Posted by bouldersoundguy View Post
    While I'm no expert on circuit design, most (all?) of the audio circuits I've delved into have DC blocking capacitors at various points out of necessity. I suspect those can't be arbitrarily low.

    What's the point of going below 20Hz?
    I remember when the movie Earthquake first came out. They had a huge bank of CerwinVega subwoofers that were supposed to put out subsonic sound at very high volume. The idea was to feel the quake, not just hear some rumble. There were stories about damage to some places when it first came out.

    It worked. I remember the feeling in my gut when things began to shake.

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    Quote Originally Posted by ecc83 View Post
    Some 'High End' designs eschew capacitors and use DC servo circuits to keep outputs at 0 volts.
    Right, but the fact that I could fool with dozens of audio circuits and not have encountered one of those means that not passing below 20Hz is generally considered completely acceptable.

    Quote Originally Posted by ecc83 View Post
    Oh! BTW BSG, there is a church organ with a 16Hz pedal pipe! In Oz somewhere I think.
    Dave.
    Yep. And my question remains. What's the point? Will reproducing the effect of a semi (sorry, articulated lorry) driving by improve people's chances of getting into heaven?

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    Quote Originally Posted by bouldersoundguy View Post
    Right, but the fact that I could fool with dozens of audio circuits and not have encountered one of those means that not passing below 20Hz is generally considered completely acceptable.



    Yep. And my question remains. What's the point? Will reproducing the effect of a semi (sorry, articulated lorry) driving by improve people's chances of getting into heaven?
    Oh! Sorry chap I wasn't arguing with you. You asked "what about the capacitors" and I replied that they can be done without.

    I have to say I do not agree with DC coupling. The idea is to do away with electro' caps so maybe a slight diversion into why?
    There is no doubt that e caps produce harmonic distortion and on test it can be seen that it gets worse as frequency falls. But this is one of those 'obvious innit? Capacitor distortion is frequency dependent" Not so. What happens is that AS frequency falls the reactance (sort of resistance) of the capacitor increases and so the voltage dropped across it increases. Once that voltage reaches about 100mV measurable (0.001%!) is observed. The solution is simple! Make the fekkin cap bigger! A capacitor 4 or five times the value necessary for the desired LF cut off point is still a lot cheaper than a servo!

    B.U.T. People, especially MARKETING people just seize on Capacitors are BAAAAAD! Lets fill the kit with vastly more complex electronics. Then again, "I" am NO expert! I have a certain level of technical understanding and that level tells me caps are fine. I could be wrong!

    I hold the same view at the other end of the audio spectrum. There are very well regarded, very high end mic pre amps that go up to 200kHz and beyond. I cannot understand why? Yes, there are specialist microphones that go past 50kHz but nothing in any studio is likely to reach 20k let alone go beyond.

    So, my view is cut your spectral cloth to the real world. 20-20k is good enough.

    Dave.

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