K5synth

Hi Paul,

I recently modified a K5 to increase the output gain and clean up the noise floor. The 150k  gain resistors made a huge improvement. I installed TL2074 op-amps to clean up the noise. These mods made the K5 come alive compared to the stock low gain setup for the TL064 chips. The slew rate of the new op-amps is so much higher the bass and lower mids are very much improved!!! Probably the same as your EQ setup you are currently using.

Awesome you improved the sound without going under the hood,  Fran



On Tuesday, March 25, 2014 1:15 AM, "Mehlhaffer@..." <Mehlhaffer@...> wrote:
  
  
>About a year ago, a friend of mine gave me a K5m, but as soon as I got it, I was completely disappointed in the sound.  Everything was so thin, dull, and wimpy. Frustrated, I quickly blamed it on the early digital design, since it fit the description of how early digital synthesis is usually criticized.
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>Finally, after a little research, I was wondering if it might be an output problem.
>Before, I simply sent its 1/4 inch audio outputs to the audio board to a nominal line level with a flat EQ.  Pretty basic stuff, right? As you read this, keep in mind that I also use a variety of other gear, like a Roland Alpha Juno 1 and an Ensoniq ASR-10, that respond just fine on my audio board with those same simple settings. But after experimenting through headphones and my PA amp, I finally decided to try some radical shifts on my audio board.  I first set the Trimpot gain on my board up very high, more of where you would gauge it for a microphone level, just before the synth starts to peak into distortion.  In order to do this, the volume control on the K5 is now set at about 40-50%.  Yes, I know this is against everything people tell you to do with a volume control on a digital synth, but hear me out: It improved the sound incredibly! It created a much bolder, immediate sound, without much for distortion or noise.
>Related to this, I also experimented with a line-matching transformer to plug it into a 3-pin XLR.  I might have detected a slightly cleaner signal, but the sound hadn't changed that much at all, so I resumed plugging it into the 1/4 inch line inputs.
>The next thing I did was radically shift the 3-band EQ.  I have the treble turned almost all the way down, about a 15dB cut! The midrange is cranked up about 15dB, and the lows are boosted about 12dB.
>After changing all of this, low and behold, everything sounds completely normal.  The synth voices are much more rounded, natural, and musical.  There is some general digital aspects to the sound, but it's got a character all its own! In fact, I really like the synth now, and I'm hearing all the good stuff I've been missing!
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>And if that weren't enough, I was even more surprised that the keyboard action from my MIDI controller now responds much better to my touch with the K5, probably because cranking up the trim gain added some compression to the dynamic range of the audio. 
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>Now, here's where it gets weirder.  I also have an Alesis QS6.2, which, like the K5, I found to be thin and dull, so I performed the same procedure with it, and now it sounds much, much better in the same way, but at the same time, my ASR-10 and Juno behave perfectly normal with normal mixer settings!
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>So through all these changes, at first I thought I was clearing up the digital idiosyncracies of the K5, but now I'm wondering if it has something to do with it's output impedance being different.  Ever since I made those changes, it seems to sound and respond perfectly normal, like it seems to be intended for.  So, how do you connect your K5 to the mixer? It doesn't seem like it should be a big deal, but these changes made a huge difference!
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>I always figured that most synthesizers should have the same audio output to a basic line level.  Am I missing something? I've never really seen anything like this in over 20 years! 
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>Thanks!
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>-Paul  
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