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Audio and capacitors...

Sure was a common problem with the Harris Stereo 80 consoles.
 
BobOnTheJob said:
Sure was a common problem with the Harris Stereo 80 consoles.

My stereo 80 is getting a minor increase from 8khz, nothing that bothers me for now.

I have 2 other cart recorders (ITC Delta and Sonifex) and the Harris (not Gates, I was wrong, sorry) is the only one that has the treble issue...
 
Digi-Key has Panasonic low-esr/low leakage electrolytics that sound good. Drop tantalum caps are about as bad as they come. I've fixed a lot of equipment from the 80s that had shorted tantalums taking down the power supply rails. Small value electolytics can be replaced by mylar or other film caps if there is enough room.

I generally only use ceramic caps in RF circuits or for RF bypassing on power supply rails.

I have also paralleled small value film capacitors across large value electrolytics and noticed some improvement in the high-end of the audio range in some circuits. It is only practical if you have plenty of circuit board room.
 
SFM-Ptgal said:
Wich are ususally tantalum, elect. or ceramic?

Most likely aluminum electrolytics, although Gates did use tantalum audio coupling capacitors in some equipment - IIRC the Gatesway II used tantalum caps.

Note that replacing one type of audio coupling cap with another (such as replacing tantalums with electrolytics) may be problematic depending upon the circuit. A tantalum has lower ESR than an aluminum electrolytic of the same value, and replacing the former with the latter may affect frequency response in some audio circuits. I discovered that early on when I took over a station with an early solid-state Gates console (I believe it was the aforementioned Gatesway II) that exhibited flawed frequency response. The cause was that a previous engineer (apparently with insufficient knowledge of component properties) had replaced some of the tantalum coupling caps with electrolytics. After I replaced those with new tantalums the frequency response returned to spec.
 
SFM-Ptgal said:
BobOnTheJob said:
Sure was a common problem with the Harris Stereo 80 consoles.

My stereo 80 is getting a minor increase from 8khz, nothing that bothers me for now.

I have 2 other cart recorders (ITC Delta and Sonifex) and the Harris (not Gates, I was wrong, sorry) is the only one that has the treble issue...
On the Stereo 80, the first hint is that the Left vs Right channels seem to vary from song to song. In my observation, that pointed to poor low frequency response due to dried up coupling caps. That console was more likely to do that than most any other model. I never did determine why.
 
BobOnTheJob said:
SFM-Ptgal said:
BobOnTheJob said:
Sure was a common problem with the Harris Stereo 80 consoles.

My stereo 80 is getting a minor increase from 8khz, nothing that bothers me for now.

I have 2 other cart recorders (ITC Delta and Sonifex) and the Harris (not Gates, I was wrong, sorry) is the only one that has the treble issue...
On the Stereo 80, the first hint is that the Left vs Right channels seem to vary from song to song. In my observation, that pointed to poor low frequency response due to dried up coupling caps. That console was more likely to do that than most any other model. I never did determine why.

At he moment the Left vs Right balance is good at all frequencies (20-20k, sforge sweep)... A few years ago output card started to make a sort of pink-noise and very low level. I've changed some caps in a output card a few years ago. It was fixed.
 
I have come across some weird faults caused by dodgy and aging capacitors. Most recent was an unbalanced to balanced converter which had this strange 1-legged audio thing going on.
Traced it to a dry 1uF electrolytic.
Replacing with low-ESR types is definitely worthwhile.
 
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