[eweitzman]

Jim,

Why do you recommend running the FryKleaner with only one set of cables at a time? The cables are all shorts to ground or to the complementary amp, so the current will be limited by the 100R output resistors. Is it that the effectiveness would be limited if the current was split between several sets of cables in parallel? What about hooking up several sets in series as you suggest for balanced cables? Or adding another pair of opamps in parallel for additional current drive?

That's a lot of questions ... I hope I can ask more than one at a time?

- Eric

[hagtech]

The outputs are all connected to the outer side of the 100 ohm resistors.  You could bypass it and add your own 100 ohm limiters for each output.  That would work.  Or drive external amplifiers.

Running cables in series also works fine.

jh

[eweitzman]

The outputs are all connected to the outer side of the 100 ohm resistors.  You could bypass it and add your own 100 ohm limiters for each output.

But that's the rub, isn't it? Let's be ridiculous: if I added 14 more outputs, each with it's own 100R limiter, then the opamps would have to put out 16 times more current.

The spec sheet for the LM386 doesn't give a max output current or power, but the graphs show, for a 12V supply, 0.3 watts at 4 ohms, and 0.8 watts into both 8 and 16 ohms (at 3% THD). What's the minimum loading that you'd like to see in this application?

Connecting RCA-terminated interconnects in series is a little tricky. I'd like to figure out if it's easier to build some sort of patch board for series connection, or just install more RCA's and limiting resistors in the box for parallel connection.

- Eric

[hagtech]

It does get a little more complicated.  There are RC filters on the power supply for the LM386 outputs (on Fry board).  These filters help remove 120Hz ripple from the wall wart, AND drop a few volts for safer operating area on the amps.  Therefore, higher output current will pull down this voltage to the point of non-operation - with too many 100 ohm output loads.  So it's a bit of a compromise.  You could probably double the number of 100 ohm loads, but no more.

Yeah, I was just playing it safe.  And it was easier to build the FryPro using the standard outputs rather than trying to get at the raw LM386 outputs.

jh