Neve Germanium 1060 Marinar L10468 as Line Input transformer , hookup question

[Biasrocks]

Alright guys,

I've verified that the line input transformer used on these older modules was in fact a 10468 which is generally used as a mic input transformer on subsequent modules.

My friends at Breakglass in Montreal have a somewhat modified Neve germanium console which features Gardner MU-2525 as the mic inputs and Marinar L10468 as line input transformers.

My question is what is the best way to hook these guys up as a line input.

Here's the transformer info

I've got two primary impedance's of 1K2 and 300R, two secondary impedance's of 1K2 and 4K8.

I'm thinking I also need some transformer gain going into the module because I'm not able get enough level for unity gain at the 0db line setting on the module.


Ideas?

Mark

Edit: Just found the attached Neve document,
not sure if this solves my unity gain issue.

 

[Biasrocks]

Here's a close up of the Marinars.

 

[Biasrocks]

And the Gardners.

 

[Biasrocks]

Both

 

[Joechris]

I recal from somewhere that some of the EMI spec Neve desks was delivered with the 468 mic trans as line trans. Just wierd backwards. secondary as primary.

 

[sodderboy]

I agree with joechris and the Neve doc is correct except for the "10K" input impedance.  If you look at the spec for the standard 31267 transformer, the most common use as a line input was with the primary at 10K and the secondary at 600 giving a 13 dB drop.  The closest you can get to the '267 with the 10468 is backwards with 4K2 primary / 600 secondary.  But that comes with a 12 dB drop in gain.
If you know that you have source impedances less than 60 ohms then you can use it 600:4K2 and get the gain that way, but you have to look at what you are connecting to the module, and what kind of impedance the actual input circuit wants for it to work properly.  If the unbalanced console input impedance is 7.5-40K it will not be the greatest fit.
Mike

 

[Biasrocks]

I agree with joechris and the Neve doc is correct except for the "10K" input impedance.  If you look at the spec for the standard 31267 transformer, the most common use as a line input was with the primary at 10K and the secondary at 600 giving a 13 dB drop.  The closest you can get to the '267 with the 10468 is backwards with 4K2 primary / 600 secondary.  But that comes with a 12 dB drop in gain.
If you know that you have source impedances less than 60 ohms then you can use it 600:4K2 and get the gain that way, but you have to look at what you are connecting to the module, and what kind of impedance the actual input circuit wants for it to work properly.  If the unbalanced console input impedance is 7.5-40K it will not be the greatest fit.
Mike

I have various schematics for the germanium Neve era, but unfortunately not for my exact module, the 1060. Of the schematics I've seen they all vary slightly on the line inputs.

I think the best plan of attack is to pull the module and draw up a schematic of the line input to see exactly what's going on there.

 

[Biasrocks]

It looks like the line input goes through a capacitor, which I'm fairly certain is not standard Neve but may have been put in there because the guy I purchased the modules from didn't have any transformers to feed the modules and that was most likely an attempt at blocking any unwanted DC voltages because of the lack of a transformer input. From there, the line signal heads off to the gain control switch into a 470R resistor, etc. This seems to follow the 1055 schematic fairly closely.

So, I'm thinking of removing the line input capacitor and directly coupling to the 470R resistor.

Anyone seen a Neve module with a capacitor on the line input before?

I also tried hooking up the 10468 as an line input transformer in the recommended way. It essentially gave me the same loss as the 31267 that are already there. So I think I'll stick with the 31267 on the line input, although I should probably compare the sound of the 10468 to the 31267 with a nod to authenticity.

I also managed to get within a tenth of a volt of unity gain at +4 by cranking the output section on each module, so I'm happy to live with that minor loss of gain which I could no doubt overcome by using the 10468 as the input with it's 12db loss as opposed to the 13db of the 31267.

Mark

 

[Aaronrash]

It looks like the line input goes through a capacitor, which I'm fairly certain is not standard Neve but may have been put in there because the guy I purchased the modules from didn't have any transformers to feed the modules and that was most likely an attempt at blocking any unwanted DC voltages because of the lack of a transformer input. From there, the line signal heads off to the gain control switch into a 470R resistor, etc. This seems to follow the 1055 schematic fairly closely.

So, I'm thinking of removing the line input capacitor and directly coupling to the 470R resistor.

Anyone seen a Neve module with a capacitor on the line input before?

I also tried hooking up the 10468 as an line input transformer in the recommended way. It essentially gave me the same loss as the 31267 that are already there. So I think I'll stick with the 31267 on the line input, although I should probably compare the sound of the 10468 to the 31267 with a nod to authenticity.

I also managed to get within a tenth of a volt of unity gain at +4 by cranking the output section on each module, so I'm happy to live with that minor loss of gain which I could no doubt overcome by using the 10468 as the input with it's 12db loss as opposed to the 13db of the 31267.

Mark

Hey Mark,

Your inbox is full. Can you sell me a 10468?

 

[ruffrecords]

I think the answer is to use the 10468 wired 300:4K8 as indicated in the Neve data sheet and use it backwards to make a 10K:600 transformer. The inductances won't be quite right so the bottom end will not be so good but Rupert's designs were always generous so I suspect the difference is immaterial.

Cheers

Ian

 

[Biasrocks]

Hey Mark,

Your inbox is full. Can you sell me a 10468?

None to sell, used them in my 33609 clone a while ago.

Mark

 

[Biasrocks]

I think the answer is to use the 10468 wired 300:4K8 as indicated in the Neve data sheet and use it backwards to make a 10K:600 transformer. The inductances won't be quite right so the bottom end will not be so good but Rupert's designs were always generous so I suspect the difference is immaterial.

Thanks Ian,

I managed to locate the proper Gardner input transformers and have been happy with the sound. I would still like to find a schematic of the 1060 channel amp if anyone has one kicking around.

Mark

 

[Tekay]

How about the 1061? Should be the same exept that it's using an external input transformer  according to John Klett's page.
PM me if you need a copy of the 1061.

 

[API]

I doubt that there is a transformer speced out on the schematic.
The whole idea with the plug in Gardners was that you could change them depending on your source and there was a whole range to chose from.
For instance the 1057 tech sheets says that the mic input can be used with a range of transformers, but noting that the line input is 600ohm unbalanced and could be used with a 10k input balancing transformer.

 

[leadbreath]

hey thanks for posting that Gardners datasheet, just what I needed!!

 

[Biasrocks]

I doubt that there is a transformer speced out on the schematic.

For instance the 1057 tech sheets says that the mic input can be used with a range of transformers, but noting that the line input is 600ohm unbalanced and could be used with a 10k input balancing transformer.

Cool info, you're right I haven't seen a Neve schematic specifying the Mic Input transformer.

The examples I've seen in the wild use the Gardner MU-2525 (600 -> 300/1200) in reverse on the mic input and Marinars on the Line Inputs. I have also seen hand drawn schematics that spec the Gardner MU-7529 (50/200 -> 600) on Mic In, which is probably not the best impedance match, but would be closer to the EMI spec.

I'm sure they're examples with Marinars on both the Mic and Line.

Edit: Found the 1058 spec sheet, and indeed it has a number of options available depending on the application.

Mark