EMT 140st, pin 2 or pin 3 hot??

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Twist Turner

Well-known member
Joined
Sep 19, 2004
Messages
155
Location
Chicago, Il
I'm stumped on this one and either don't know enough to tell from the schematics or it isn't marked.

http://www.danalexanderaudio.com/EMT/EMTStereoTubeSchem.jpg

http://www.danalexanderaudio.com/EMT/EMT140ST.jpg

Can anybody figure this out, or just know off hand. I may have to dig up Jim Cunninghams number and give him a call, he rebuilt the preamp section.

This is the last piece of outboard gear I need to hook up after moving my studio. Next I have to hook up about 40 channels of mic pre's!! I"ve been soldering for 2 months strait 12 hrs a day, no end in sight yet. HELP!!!!!!!!!

Once I get that done, I have to rack 2 sphere eq's, 2 melcor eq's, 4 quad eight pre M61's, 2 rca 71's, two sphere m1200's, 2 spectrasonics 101's, 2 calrec compressors, one emt 261 compressor, 2 Tele u373a's, 2 tele v372's, 4 v72's , 3 v77's and a U273! Whew, I'm tired just thinking about it. Never enough hours in a day for me.
 
If it comes down to guessing, I'd go with pin 2=hot, since the Europeans were using that standard long before we adopted it. (When I was in radio, not many years ago, the old pin-3 standard was still hanging on in some quarters). The best way, in the absence of solid data, would be to check it for yourself. And if you get it wrong, it's easy enough to switch it around later. If the output of the reverb is 100% "wet" signal, don't be surprised if you don't notice a big difference either way.

But wait a minute... I notice a clue: on the lower right corner of EMT140ST.jpg, notice that the output connector block is marked "American model", and also the lighter-colored wires go to pin 3. The lighter-colored conductor is generally--but not always!--used for the "plus." So they may have gone with pin-3 hot after all, at least for their American customers.
 
I may just hook it up and see if I can tell which is which, but with reverb it's gonna be difficult, I can make a shorter reverb and possibly tell, but no way to buy pass the plate, it's always in(too bad i didn't think to check my previous connection before I moved it 9 months ago.

I only got 3 out of about 60+pieces of gear out of phase in my outboard rack, which I just corrected today. Some of the stuff with barrier strips doesn't say one way or the other which really sucks.

Still looking for hookup in for for the Fairchild 658, its humming like crazy no matter how I hook it up.
 
I recall Jim's commentary in his Echoplate manuals being along the lines of "polarity is indistiguishable and unimportant with regards to the reverb signal". I know you want to be technically correct, but I'm not sure it really matters in this case.
 
I don't have the schematic handy, but most of the EMTs I ever used were fully balanced in & out.

In that case, it doesn't matter, so long as you make the ins & the outs both the same... as is true with most balanced outboard equipment...

Reverse it on the way in, re-reverse it on the way out, the result is the same as no polarity reversals. -No difference... unless you want something like the asymmetric distortion of a single-rail preamp to be in a particular pole, in which I have nothing more to add. Most people who care about that sort of thing are insecure wackos who need to be TOLD what sounds good, and that's all there is to it for me!

Keith
 
Ok, I finally got it hooked up.

It is really difficult to tell with reverb, but I do get phase cancelations on the bottom end when the phase is inverted so I'd have to say that Pin 2 is hot on this, although as has been pointed out in previous posts, it's really, really hard to tell and probably doesn't make much differnece either way. But since I"m doing a new install I want to make sure everything is in phase from the beginning(I can screw it up later right???) :grin:
 
[quote author="Twist Turner"]It is really difficult to tell with reverb, but I do get phase cancelations on the bottom end when the phase is inverted[/quote]
Impossible.

Now if you're talking about inverting the returns and leaving the send(s) uninverted, that's entirely possible to a somewhat limited degree. But that has NOTHING to do with pin 2 hot/pin 3 hot, beacuse no matter which way you do it, you'll still get the same result whan you invert the POLARITY (note: not 'phase'!) on the return or send alone, whether you wired it pin 3 hot in & out, or pin 2 hot in & out.

Keith
 

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