10468 transformer used as line input by Neve themselves

I´ve found this in an old BCM10 manual, stating 10468 transformer may be used instead of the 31267 transformer:



Which means, by using a relay, mic and line input may share the same transformer and the 31267 not needed anymore, saving some cash.
Any comments?

Probably works fine. The other alternative would be using an H-pad.

rodabod said:

Probably works fine. The other alternative would be using an H-pad.

Click to expand...

By fooling the transformer into thinking the line source is a mic... An H pad may be as expensive as the transformer itself wouldnt it?

Reversing the 10468 would make the line input of a neve exactly the same as with a 31267 !!!

I think it's possibly the EMINeve's and the desks for AIR that used a mic in for the lines.  Although, in this case, it was configured the usual way round with a U pad in front.  When things are equal (the pad is of a value to get the same level on the secondary as from a 31267...18dB or thereabouts), the headroom is better on the Pad/10468 combo.  I did measure it at one time but I don't remember the details and by what amount the difference was  

I suppose someone like Geoff Tanner would be the one to ask.

Wonderlandaudio said:

By fooling the transformer into thinking the line source is a mic... An H pad may be as expensive as the transformer itself wouldnt it?

Click to expand...

If a pad costs as much as a transformer, you're using some VERY expensive resistors or you're paying someone $50 a minute to match a pair.. 

A single pad on the input is all you need so, 3 resistors (or 4 if you centre-tap ground the shunt).

All other attenuation (5dB increments0 happens on the secondary as it usually does with Neve. 

No, the AIRs used a VT24470 10k/600 for the line ins...
I suppossed that technical sheet was made just in case they got short on 31267s... Notice that the 10468 wired that way is 4K8 / 300, but if loaded 600 on the sec the source will see 10K, just as in the 31267.
I already asked Geoff. He told me that, although the sheet is authentic, he never saw it being applied.

Winston O'Boogie said:

Wonderlandaudio said:

By fooling the transformer into thinking the line source is a mic... An H pad may be as expensive as the transformer itself wouldnt it?

Click to expand...

If a pad costs as much as a transformer, you're using some VERY expensive resistors or you're paying someone $50 a minute to match a pair..   

A single pad on the input is all you need so, 3 resistors (or 4 if you centre-tap ground the shunt).

All other attenuation (5dB increments0 happens on the secondary as it usually does with Neve. 

Click to expand...

Thats right... I was thinking as a variable H pad... 

Wonderlandaudio said:

I already asked Geoff. He told me that, although the sheet is authentic, he never saw it being applied.

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Yes, I've never seen it done that way either.
If you can, ask him about the 'U' in front of a regularly oriented 10468.  I've seen that one done but don't remember where. 
Maybe it was just the EMI-Neve's.  Or maybe it was some other desk?  Regardless, I remember talking to Geoff about it years ago. 
Also, in that particular case, there were two 10468's used and it was for technical reasons rather than cost or shortage of 31267's.

Anyway, I think that way would be a better (and fine) way of using just one transformer for both inputs than having to flip the thing around.  Give it a shot. 

Yeah, the EMI-Neve's used 10468's for their line inputs.  Seems the EMI techs prefferred its performance characteristics compared to the 31267's.  Not sure what their criteria were, but I do remember Geoff saying that in the configuration used they gave a lower distortion figure.  I've always found this interesting, but have never tried one in place of a 31267 in any of my builds.

It seems Geoff fancies the EMI-Neves more than just about any other.  I've heard him refer to them as the best Neve consoles ever made.

JC