Let's say you have a 33752 doing all its normal things from its 5534-based -6dB unbalanced output – sending to four aux busses, assigning to eight groups through an optional panner, and providing signal to solo, all through appropriate summing feed resistors. 33752 output stage schematic attached.
If you wanted to derive a balanced direct out from that same output, the most Neveish way to go about it would be with an LO2567 transformer, with a 1k5 resistor and .01µF cap in series across its output to control ring. Transformer spec in reply below.
If wired series/series, you get 4dB of free gain, and your direct output lives at -2dB. You've achieved a great signal, but it's a bit impractical if you're sending both these direct outputs and +4dB post fade outputs (groups, mainly) to tape, and later trying to use them at the same level in the mix. You end up needing to add 6dB of noise gain at some point, and there's really no way to align tape to accommodate both levels. It's less of an issue in a DAW, but still creates a bummer of a monitoring situation during tracking. It would be a shame to have to attenuate post fade outputs down to the direct output level.
It looks like the easiest solution is to mimic the output of a 1081 (whose 340 output amp is pretty similar in function to the 33752's output stage) and run the trafo in parallel/series for a healthy 10dB of free gain, putting your balanced output at +4dB. 1081 output stage schematic in reply below.
Here are my questions:
Is it an issue to ask this shared output to drive a 50 ohm load? Is the 200 ohm load similarly problematic, given the multiple feeds?
What options do you have at this stage to take advantage of the free gain other than a unity buffer, and would the best option for that be another 5534?
Would it be preferable to place a THAT 1646 here, before the transformer, and leave it wired series/series? This would also bring the output to +4dB. If that's the way, how would one best derive an appropriate supply for the 1646 from a +24V supply with a 0V reference?
A Geoff Tanner anecdote on the topic:
On most vintage Neve consoles there is no separate Studio Loud Speaker amplifier… it’s wired off the unbalanced output of the monitor amplifier using an external transformer to balance the signal. On the 8058/68 the external transformer is a LO1173 with a primary impedance of around 70 ohms and 8db step up. On a 1271/2 you would use an LO2567 with a primary impedance of 200 ohms and 4db step up (connected with a 100uF coupling capacitor).
What Mister Neve fixer forgot to take into consideration was that, by retaining the original LO1173, the Monitor 1271 was driving three times the original intended load and dramatically changing the conditions around the 2N3055 driver stage.
The effect was that, at 0VU, the console sounded reasonably “Neve like” but the minute the signal was driven into the red on the VU’s (above +7dBu) the Monitor 1271′s went into premature clipping and sounded like crap. Obviously, the rest of the console could be working famously well but you listen to the mix on the monitor system and this will be what the artist/producer hears.
A famous LA producer was the first to use the console and, needless to say, this first session did not go well! I was called in and we swapped the LO1173′s for LO2567′s… to produce a much sweeter sounding console with no headroom issues.
If you wanted to derive a balanced direct out from that same output, the most Neveish way to go about it would be with an LO2567 transformer, with a 1k5 resistor and .01µF cap in series across its output to control ring. Transformer spec in reply below.
If wired series/series, you get 4dB of free gain, and your direct output lives at -2dB. You've achieved a great signal, but it's a bit impractical if you're sending both these direct outputs and +4dB post fade outputs (groups, mainly) to tape, and later trying to use them at the same level in the mix. You end up needing to add 6dB of noise gain at some point, and there's really no way to align tape to accommodate both levels. It's less of an issue in a DAW, but still creates a bummer of a monitoring situation during tracking. It would be a shame to have to attenuate post fade outputs down to the direct output level.
It looks like the easiest solution is to mimic the output of a 1081 (whose 340 output amp is pretty similar in function to the 33752's output stage) and run the trafo in parallel/series for a healthy 10dB of free gain, putting your balanced output at +4dB. 1081 output stage schematic in reply below.
Here are my questions:
Is it an issue to ask this shared output to drive a 50 ohm load? Is the 200 ohm load similarly problematic, given the multiple feeds?
What options do you have at this stage to take advantage of the free gain other than a unity buffer, and would the best option for that be another 5534?
Would it be preferable to place a THAT 1646 here, before the transformer, and leave it wired series/series? This would also bring the output to +4dB. If that's the way, how would one best derive an appropriate supply for the 1646 from a +24V supply with a 0V reference?
A Geoff Tanner anecdote on the topic:
On most vintage Neve consoles there is no separate Studio Loud Speaker amplifier… it’s wired off the unbalanced output of the monitor amplifier using an external transformer to balance the signal. On the 8058/68 the external transformer is a LO1173 with a primary impedance of around 70 ohms and 8db step up. On a 1271/2 you would use an LO2567 with a primary impedance of 200 ohms and 4db step up (connected with a 100uF coupling capacitor).
What Mister Neve fixer forgot to take into consideration was that, by retaining the original LO1173, the Monitor 1271 was driving three times the original intended load and dramatically changing the conditions around the 2N3055 driver stage.
The effect was that, at 0VU, the console sounded reasonably “Neve like” but the minute the signal was driven into the red on the VU’s (above +7dBu) the Monitor 1271′s went into premature clipping and sounded like crap. Obviously, the rest of the console could be working famously well but you listen to the mix on the monitor system and this will be what the artist/producer hears.
A famous LA producer was the first to use the console and, needless to say, this first session did not go well! I was called in and we swapped the LO1173′s for LO2567′s… to produce a much sweeter sounding console with no headroom issues.