Phoenix Area Tech Question

WKSmith said:
Do we want to supply it with a 9v supply or +48v from the mixer?
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Ideally, 48V would be simplest to use.

9V would work well with a little adapter fun.

Either way, unless the photos I saw weee wrong, it will need a TRS plug and cable to replace the original attached to the mic.
 
Joe Bfstplk said:
Ideally, 48V would be simplest to use.

9V would work well with a little adapter fun.

Either way, unless the photos I saw weee wrong, it will need a TRS plug and cable to replace the original attached to the mic.
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Could also pipe in a D cell and stay in the replaceable battery realm with the external DC piped in. Simpler, would likely last considerably longer than an AA....
 
https://www.parts-express.com/D-Cel...hu5HMFUnaNN0uObzpINb_yxNHRwG4BOMaAoQ9EALw_wcB

D cell battery holder, the female 1/8" TRS to dual male 1/8" TS adapter posted up thread, and a female TS to whatever cable that we could cut the other end off of and hook to the battery holder would be probably the simplest way forward. Could get two battery holders and have a pair of D cells in parallel for longer life, if it needs to be. :)

It'd also be closest to its original operating parameters (i.e., a 1.5V battery), so less likely to sound any different than using the AA inside it....
 
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Joe Bfstplk said:
With that provenance in mind, I was trying to mod the mic as minimally as possible and leave it still capable of being used in its original manner.... :)
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I agree that a D cell solution would last much longer. But a phantom powered box would also be super simple to interface that mic with modern mixers.

It would be a worthwhile endeavor to send the good Dr one.. and maybe a few other folks that know what this mic is for.
 
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WKSmith said:
I agree that a D cell solution would last much longer. But a phantom powered box would also be super simple to interface that mic with modern mixers.
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True. However, both anecdotal and personal experience with super simple circuits (like the mic's buffer likely is) tells me that the power supply can affect the tonal quality. Careful choice of the power supply's output impedance would be important to mimic that of the AA battery. D cell would be a little lower, but still comparable. The simpler the circuit, the more the qualities of each part make a difference, and the power supply is a part of the circuit. :D
 
Joe Bfstplk said:
True. However, both anecdotal and personal experience with super simple circuits (like the mic's buffer likely is) tells me that the power supply can affect the tonal quality. Careful choice of the power supply's output impedance would be important to mimic that of the AA battery. D cell would be a little lower, but still comparable. The simpler the circuit, the more the qualities of each part make a difference, and the power supply is a part of the circuit. :D
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I have found simpler pretty much always sounds better. If there was the perfect theoretical piece of wire with gain .. we would all find nirvana .
 
Found some old literature with a schematic of the mic's circuit:
EC-5%201.jpg


Gonna need to get two wires in there to inject the 1.5V where it needs to go. So much for unchanged operation, unless we can find a way to sneak two extra wires in the housing somehow without compromising the sound and operation of the unit.

Two resistors are unmarked on this schematic, but on the EC-3S schematic, they are: R1: 300M and R2: 3.3k.
EC-3S%201.jpg


Pretty basic circuit. It's got a 3.3k bias resistor tied to the gate via the 300M, and the output signal voltage is developed across the 2.2k resistor, with the output approaching unity gain, but buffered for low impedance inputs. Pretty much the same circuit as a vacuum tube cathode follower, but with a JFET and much lower voltage.... The battery is floating, so not directly referencing the mic case and sleeve connection on the mic plug. If we can snake another two-conductor cable through the strain relief for the existing one, we can inject DC in there easy as pie - tie the two new wires to where the battery connects. Literature claims a 6000-1200 hour battery life, with 150uA of current draw. Not sure what's going on with the one @dr bonkers has to be eating batteries....
 
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Joe Bfstplk said:
Currently, it has a 1/8" TS plug and coax cord, if the pics I saw on the forum were correct.

My plan would replace that with a cord set up with 1/8" TRS, and send DC in via the ring and shield, keeping the mic as close to original operation as possible by connecting the ring to the appropriate internal AA battery terminal. A stereo splitter would let the output be connected as it was before and give an injection point for the DC. A couple diodes and a resistor would make a decent regulated voltage drop, and could be wired up on the male TRS plug of the other stereo splitter with little difficulty, so you plug the 9V in one side and get 1.4-ish Volts on the other. I opted for a high-ish current capability for the supply, based on @dr bonkers stating it was killing AA batteries.
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That sounds awesome.

Let me know where I can drop it off and when as well as how much I would owe you.

Please PM me.
 
Dave Merrill said:
Wonder how those users make it through whole Dead shows.
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Marantz' literature states 6000 hour battery life. Given no switch to disconnect the battery when not in use, that includes time in the carrying case. I wonder if there is a fault that is draining the battery quicker....
 
Joe Bfstplk said:
Marantz' literature states 6000 hour battery life. Given no switch to disconnect the battery when not in use, that includes time in the carrying case. I wonder if there is a fault that is draining the battery quicker....
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That's what I am thinking or a component out of tolerance that is draining it faster. Most battery powered devices don't see use for almost 50 years.
 
Looking forward to seeing how this works out and what you guys end up doing. I agree it sounds like something is faulty and draining the battery too quickly. Maybe the FET is bad?
 
I love this thread!

I don't care about the technical parts as I'm not really into circuitry (even though I have an AS in Electronic Engineering - long story, 30+ years ago).

It's the human nature and "help thy neighbor" attitude that exemplifies this forum a lot!

And one can hope that we'll get the chance to reap the rewards when the eventual Cab pack is released.

Well done @Joe Bfstplk and @WKSmith!
 
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