Tascam 320 vs 520

  • Thread starter Thread starter A. Lacy
  • Start date Start date
@sweetbeats correct me if I'm wrong, but the M-520 is pin 3 hot on the XLRs. don't know about the 320. There's a polarity switch on the inputs which will take care of that. I've wired most of my DIY mics pin 3 hot. I believe the balanced outs are also pin 3 hot.
 
Blue Jinn said:
@sweetbeats correct me if I'm wrong, but the M-520 is pin 3 hot on the XLRs. don't know about the 320. There's a polarity switch on the inputs which will take care of that. I've wired most of my DIY mics pin 3 hot. I believe the balanced outs are also pin 3 hot.
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Looks like both the M-300 and M-500 series consoles are indeed pin 3 hot on the XLR inputs.

FYI there isn’t a “polarity” switch on the M-500. It’s a “phase” switch. Phase and polarity are not the same thing. The phase switch is after the balanced signal is unbalanced by the input amp. There are two opamps that make up the output booster amp of the mic amp. One is inverting and the other is non-inverting. The PHASE switch switches between sourcing the non-inverting amp’s output vs the inverting amp’s output…flips between sourcing positive going signal vs negative going signal. It has nothing to do with swapping pins 2 & 3 of the XLR jack, which is what you’re talk about. There’s no switched control for that. You know this already but for the possible benefit of other readers, in the balanced interconnect there are two signal conductors, sometimes referred to as “hot” and “cold”, and other times “high” and “low”. I prefer the latter. Because what’s going on there is you have a signal waveform on one that when it is positive, the other signal conductor has a mirror image of the waveform that is polar opposite and negative. When these two signals are summed, any outside interference induced into the conductors are cancelled out. And that’s the only real purpose of balanced interconnects is signal interference abatement. It’s important to either at least know if you have gear that’s pin 2 hot vs pin 3 hot and which is which, or to makes sure all your gear is the same. The reason is in certain situations if you are summing similar balanced signals, like maybe when you’re doing parallel compression, and all your stuff is pin 2 hot, but you introduce a pin 3 hot compressor into the signal chain and it’s internally unbalanced, when you sum the two signals, most of the signal is going cancel itself out. Sometimes these issues come up in complex setups and it can be maddening to track down what’s happening.

Anyway, the only way to convert an M-300 or M-500 series console to pin 2 hot is to either get out the soldering iron and swap the pin 2 and pin 3 wires on the back of the XLR jack, or use an external adapter that swaps the connections at the input or a custom cable.
 
sweetbeats said:
Yeah I’ve distracted myself now with the desire to test if the 5532 works in the M-500 mic amp…I have a couple spare M-500 input PCB assemblies pretty accessible. Would be pretty easy to hook them up on the bench and check…I just have several patients opened up on the workbench right now…grr.
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So I dug out one of my spare M-500 input PCB assemblies…I’m going to remove the mic amp opamp, install a socket, put an 072 back in, measure the DC offset, and then put a 5532 in there and do the same…see if it’s happy.

915DCBCB-AF02-45CC-97E4-484E4188566F.webp
 
There was a similar chip called the 5530 that the TASCAM tech I knew would use instead of the 5532. Supposedly, it was designed specifically for -10 device circuits whereas the 5532 was not.
 
itsphilyoung said:
Just found this thread and am curious to know how the swap went, @sweetbeats
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Yeah hi…I must have updated information in some other thread…maybe the thread for my prototype Tascam console that has the same mic amp as the M-50/M-500 series (which is also the same as the MX-80 rackmount mic preamp, and the 388 mic preamp). The 5532 works. Almost no difference in DC offset…same for the OPA2134.
 
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