Tesla EMR 425 mic pre, diagrams &/or pinouts needed ?

[Rob Flinn]

As it says in the title I'm looking for the diagrams &/or pinouts for the Tesla EMR 425 mic pre.

I'm trying to rack this for someone who I think bought it from Bongolijus on this thread http://www.groupdiy.com/index.php?topic=37389.0

I tried PM'ing him but have not got a reply.

 

[Rob Flinn]

Just bumping this on the off chance that someone can help with this ?

 

[staras]

It's hard to find. I still have few laying around, but I can anything to do with it, because can't find any info.

 

[Rob Flinn]

It's hard to find. I still have few laying around, but I can anything to do with it, because can't find any info.

That's odd because you say in your black market advertisment for them ( http://www.groupdiy.com/index.php?topic=37389.0 ) "Sound is very good – it’s real East European API! "  It seems rather misleading to not have put in the ad that you have never had them working, but then say that the sound is very good & make comparisons with API.

Anyway that aside:

The problem I have initially is whether they run on a bipolar supply (for the op amp) or a single +24 for the discreet part of the circuit which is split for the op amp.

The 2 small silver cans are relays so it maybe be that they are not switched the right way so no signal is getting through.

The switch on the front is not a pad, it is a switch for phantom power.  the symbol next to it is a microphone & when depressed the symbol has a capacitor symbol to indicate that it is for condenser mics.

Did you sell them to anyone else who mananged to get them working  ?  If so maybe they can supply the missing information ?

 

[staras]

Ohh, I just copy-paste the info from some ebay guy who was selling these too. My friend got a lot of ten of these, don't know from where. I just leaved two for my self for the future, and he didn't sell any of these at that time, don't know how about now.
I never did the comparison with API

It seems is top secret in a google

I'll contact him, if I will find something, let you know for sure.

 

[Rob Flinn]

thanks bongo if i figure anything out I'll post it here

 

[Rob Flinn]

Bongo I've figured it out if you PM me your email address I can send you a photo with the connections details marked on it.

The switch on the front is in actual fact a pad, so you were right.

It requires a bipolar PSU.  I ran it up on + and - 15v.

It has a maximum of about 56dB gain with the brief amount of testing I had time to do.

You cannot turn the mic amp right down, the control is in a range for example probably between something like 30 -56 dB

Unfortunately, I have to go out & mix a gig so I can't give you much more info at the moment

 

[Zab]

Not to revive a long dead thread, but in case someone else stumbles upon it looking for info... the datasheet for the hybrid op-amp used in the circuit calls for +/- 20 volts (can handle a max of +/- 24). Trying to find some more documentation for the circuit, in case anyone has any or is in need...