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Thread: By-Pass a preamp

  1. #1
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    By-Pass a preamp

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    I have an old AKAI Quadraphonic. 202D-SS to be exact. I am curious if it is possible to bypass the preamp that is in it all together?

    The reason being that I get unwanted distortion when the signal peaks. My understanding is that if I use my quality preamp with higher headroom then I will get the mystical "tape compression". I assume I am already getting some just by recording, but you know what I mean, so.........anyhow.

    Can I just follow wires from the inputs and find where they hook-up later in the signal chain and run my preamp to that?

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    Rather then opening up the reel to reel and possibly damaging something in there, just plug the output of your "quality" pre into the line inputs on the back of the deck and turn the line level on the AKAI to about halfway so that it is still clean and adjust your outboard pre's output to get a healthy level into the recorder.

    With any luck, that should do the trick and get you a smoother, cleaner sound for tracking.

    Cheers!

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    I'll try hooking my Preamp into the line in and using the gain on my outboard preamp, but the mic pres on the AKAI are still functional even when you use the line in. So inherently(?) the headroom for clipping won't change--From what I understand.

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    As long as you turn the Mic gain controls to zero, you will effectively take what ever noise they generate out of the signal chain.

    As for headroom on the tape recorder, there are two areas to consider.

    Electronic headroom, which if you keep the line level inputs at a normal or nominal setting should not clip before the tape does. If they do with a clean signal feeding it, that isn't clipping itself, the circuitry is either badly out of adjustment or defective.

    Tape headroom is determined by several factors and internal adjustments. The type of tape that is used on the machine will determine what the bias, level and eq setting should be adjusted to.

    The calibration process is not a simple one and is beyond my ability to tell you a step by step procedure of how to adjust it. This process involves using professionally made test tapes, a few technicians tools like an oscilloscope and meter that can accurately read voltage and TV tuner type screw drivers that have plastic tips to turn sensitive pots inside the deck.

    If you suspect that the deck is out of adjustment, seek out a qualified service shop that can do a calibration.

    If you have an external noise reduction unit, like a dbx unit as an example, use it! As dbx can eliminate any tape hiss you might be hearing and it will also improve the headroom characteristics of the tape because it compresses the signal as it goes to tape and re-expands it on playback so that you get a recording that is as quiet or even better then many digital formats. It also allows your tape deck to operate at a lower level where there is less distortion and with its widest frequency response.

    Good luck!

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    Well, all I can say is that I thought tape does not distort, it saturates. And I am getting distortion. ANd I want it to stop. Now. I am sure the thing could use a good demagnitization and head alignment....and yes, a dbx unit. But that doesn't change the fact that I have a halfass preamp for my front end!!!!!!!!!!!

    This is driving me nuts.

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    I thought tape does not distort, it saturates.
    Saturation is when your tape can no longer store any additional loudness. At the early stages of saturation, you will get a mild and pleasing tape compression effect. When you really bury the meters into the red, you end up with UGLY distortion.

    Saturation is a form of distortion.

    Think about a fuzz guitar. At the mild settings the guitar takes on a new tone and feel. At higher settings, the notes you play are only distinguishable if they are played singly, like in a solo. When you play chords with heavy distortion, many of them will sound bad because you can't hear the notes from all the harmonic distortion.

    Recording tape takes on a similar characteristic when you go too crazy with the levels.

    As I have already stated, if you feel the recorder is out of adjustment and alignment and is also in need of de-magnetizing and cleaning, then for god's sake, look after those issues first, then learn a bit of analog electronics theory.

    This is driving me nuts.
    You're not alone.

    Cheers!

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    Well I can tell you right now this is not the tape itself being overloaded. It sounds like a cheap ass am/fm radio that has the volume up WAY to loud.

    thanks for the help though.

    Where is A Reel Person? I need a second opinion, I am in denial right now.

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    Tape will indeed distort! Ever used a portastudio? Tape gets fuzzy and then crackles.

    Wherever you see the word warmth describing audio just mentally replace it with distortion. It can sound good or it can sound bad depending on how much and on what.

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    ?!?!?!?!?!?!?!?!?!?!?!?!?!?!?

    But I thought that all the 80's rock bands with the HUGE drum sounds were from rrecording at extreme levels, letting the tape saturate a good deal. This is too much. I am sooooooo disapointed.

    But does anyone know if it is a simple mod to be able to bypass the AKAI pre completely. I have my Davisound Preamp that I would like to use but apparently sending it through another pre, be it at 0db rendering it off, still affects the Davisound quality. Or so I was told by those who convinced me to buy it, then said I can't use the mic inserts on my Roland if I want to hear the "quality" of the Davisound. So I need a "quality" A/D converter also, so I can send a "quality" signal, uneffected to my Roland.

    Well, it seems cheaper to test this theory with a bit of splicing than on a $800 A/D converter.


    Thats enough ranting here. Sorry.

    (but don't buy anything that doesn't have a company name you can find MASS amounts of information on)

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    Not intending to start any arguments here, but every time you pass a signal through an additional stage of amplication it is distorted. This happens whether or not the stage is turned to minimum or maximum or anywhere in between.

    If you feel competent to hack into your equipment and feed in the preamped signal at a different point-- then try it.
    Last edited by Derek Verner; 09-02-2003 at 03:14.

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