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> with the fader central, the two sources were at equal strength

Sounds like they looked at mixing differently in that time and place.

Today we put one hand on fader A, other hand on fader B, and move them oppositely.

I think they had one hand on an A/B fader, and another hand on a master fader. If the two sources were known to be matched, the second hand was not needed. This and the non-crossing action makes the job easier.

I'm also thinking this goes with uncertain fade times. It is tough to get the B projector speaking just as the A projector tails-out. The end of the local cabbage-report may not be the exact moment the London News starts. You must "hover" with both sources full-up from the time the transistion may start until it is surely complete. The noise level rises, but should be acceptable for the few seconds a good transistion will take.
 
PRR said:
> with the fader central, the two sources were at equal strength

Sounds like they looked at mixing differently in that time and place. .

They certainly did. Elsewhere on the same site they describe the topology of a 4 channel mixer. Inputs come enter in pairs and each pair goes to a cross fader. The output of the two cross faders go to another cross fader and its output feeds a master fader. This was the 1930s when broadcasting was in its infancy in the UK. Lots of things were done differently. For example, they had different studios for different ambiances and a radio play would often use three or more studios during its transmission.

Cheers

Ian
 
He shoots, he scores.

Thank you, please drive through.


I bet they are independent output so the external mixing resistors can be chosen depending on the number of channels.

The 1930's mixer description makes perfect sense to me.  I imagine a two studio setup, with two mics in each.  One choice is 'which mic in studio A?', the other choice is 'which studio?'.  Generally keeps confusion down knowing that knobs should mostly be fully one side or the other of the throw when no mixing action is taking place.  The crossfade itself, or the mixing of multiple sources from multiple studios would be the 'action event' for the operator, and the knob appearance would alert anyone easily to the operation at hand.  It's kind of clearer to follow than a bunch of pots all turned up, with routing switches selected differently. 
 
emrr said:
He shoots, he scores.

Thank you, please drive through.


I bet they are independent output so the external mixing resistors can be chosen depending on the number of channels.

The 1930's mixer description makes perfect sense to me.  I imagine a two studio setup, with two mics in each.  One choice is 'which mic in studio A?', the other choice is 'which studio?'.  Generally keeps confusion down knowing that knobs should mostly be fully one side or the other of the throw when no mixing action is taking place.  The crossfade itself, or the mixing of multiple sources from multiple studios would be the 'action event' for the operator, and the knob appearance would alert anyone easily to the operation at hand.  It's kind of clearer to follow than a bunch of pots all turned up, with routing switches selected differently.

I forgot to mention that the mixer was not responsible for setting levels and the mixer itself was 100% passive. Setting levels was done by engineers in a completely separate area where all the mic pres lived. Engineers patched mics to pres and outputs to mixers and set levels.

It is easy to see how this way of doing things spilled over into early music mixer designs where the separate amps and the mixing pots were housed in the same enclosure and pre-patched.

Cheers

Ian
 
Ah!  Makes even more sense. 

But still, the mixer is the 'turn it down guy' by default.  So they had 'turn it up guys' and turn it down guys'.  Elegant. 
 
Ian,

Glad to help.

Many of us have in our lifetime amassed a ton of old documentation that is hard to find now more, and it feels good to share with other colleagues with the same interest.

--Bo
 
Bo Hansen said:
Ian,

Glad to help.

Many of us have in our lifetime amassed a ton of old documentation that is hard to find now more, and it feels good to share with other colleagues with the same interest.

--Bo

But not with the general public?  Many of *US* have also amassed documentation that we are happy to share with anyone in need ;-)
 
Hey Guys

This is interesting. I'm actually on the hunt for some odd ball Painton Rotarys right now for a client. The originals were 20 position and gave a range of 10k-100k. They look just like the Daven's of that era, but in this use they're wired up as a variable resistor instead of a voltage divider.  Looking for a replacement, but the shielded can is important because this is in a feedback loop.  Any chance somebody can pass any into on these along?

-justin
 
> At the centre position, both halves have 0dB attenuation. Rotating clockwise from the centre, one half stays at 0dB but the other half attenuates, slowly at first then rapidly to a total of about 38dB. Rotating  anticlockwise from the centre the opposite happens with one half attenuating and the other staying at 0dB.

Wireless World Jan 15 1937 has a discussion of two types of BBC dramatic controls.

They describe a group fader which *may* do what you describe.

"The circuit of this mixer originally was such that, while one of the groups was being faded out, the programme level from the other group remained constant, and vice versa."

EDIT- this 3-page clip isn't totally readable. The original is some better, but much larger (whole issue).
http://www.americanradiohistory.com/Wireless_World_Magazine.htm
1937 Jan

I love the parting comment: "The time is rapidly approaching when it will be impossible to add more facilities to this type of unit, otherwise the finished product will be too cumbersome for operation by one man." 15 knobs?
 

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PRR said:
"The circuit of this mixer originally was such that, while one of the groups was being faded out, the programme level from the other group remained constant, and vice versa."
That is the exact requirement for x-faders on disco mixers; I learned that the hard way when I was "arm-twisted" to design one.
There may be a market for recycling museum exhibits.  ;)

BTW, this article is very interesting, IMO symptomatic of the profound dichotomy between scientists (those who designed) and operators (who were told how to operate), that was endemic at the BBC and transpired at EMI till the late 60's.
I must admit I haven't grabbed everything, in particular when it comes to the echo connection
"while the sleeve connections
of the " DC Input Echo " jacks are
wired to the negative winding of their respective
echo change -over relays. By connecting
the sleeve contacts of the amplifier
output jacks to the negative of a battery
and the positive winding of the echo
change -over relays to the positive of the
same battery, the particular channels desired
may be connected to " echo " when
the sources are connected to the input
echo channels in the control room."
I think a proper schemo would have taught more than these words.
 
mgriffith said:
Anything like the ones on the Johnny Longden desks http://www.orbem.co.uk/longden/longden.htm

Quite possibly. The division of channels into two groups (often on for program and the other for echo) with a cross fader between them seems to be a fairly common topolohy.

Cheers

Ian
 
Quite off-topic but perhaps of some interest to folks in this thread.

The BBC's Broadcasting House was a Very Big Deal.

Interestingly they did comply with the contract to "stay put"-- coming up on 83 years, which is incredibly long for what we now call a "media corporation".  (Although 30 Rock, the NBC/RCA/GE home in NYC, is right behind.)
 

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And it is indeed incredible that 30 Rock is still in use, after many remodels. 
 
www.orbem.co.uk/bh32/bh32_8.htm

8cr_fadeunit.jpg


"A four-channel fade unit at one of the control positions. The two outer faders each controlled two sources, cross-fading between them. The central fader combined the outputs of the outer ones in the same way and the output of that fader was fed to the main control, lower left."

So top-left is Ann or Bob. Top right is Cindy or Dave. Top center is Ann/Bob or Cindy/Dave. Lower left is overall.

Maybe I lived in the wrong decades, but it sure makes more sense to just have four mono (not X-fade) knobs, even if I give-up a Master knob.

Also it does not scale well to 5 or 6 inputs.
 
I just remembered that one early Collins Radio Speech Input Assembly in America has a center detent dual pot for a pair of turntables.  I assume off in the center detent.  Everything else I can think of over here has single pots per TT input. 
 

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