Neumann PV46 Racking

[timtom]

I got one Neumann PV46 and want to rack it to use it as a Mic and Line Pre.

I would like to replace the R6 (R106) 200ohm trimmer with a pot.
200 ohm pots are hard to get or very expensive.
Is it possible to use a 1k pot with a 250r resitor in parellel to get those 200 ohms?

Thanks,
Tim

 

[radardoug]

Yes but the law will be terrible, all cramped up at one end. Better to use a switch and resistors, more precise too.

 

[[silent:arts]]

I would like to replace the R6 (R106) 200ohm trimmer with a pot.

You know this is a fine adjust of only +/- 1dB?

 

[timtom]

Thanks for your help. I thought the range would be a bit bigger. +/-1 db is maybe not worth the effort.

 

[gyraf]

PV46 is nice for a line amp, but don't expect too much of it as a mic amp..

For gain adjust you should vary the R(GK), not the finetrim

/Jakob E.

 

[adamasnan]

PV46 is nice for a line amp, but don't expect too much of it as a mic amp..

For gain adjust you should vary the R(GK), not the finetrim

/Jakob E.

Tim has a PV46D, has 46db gain, sounds great as mic pre.

On the other hand I have a pair of PLTV-B, which are similar to the original PV46, why do you feel it falls short of being a good mic pre, out of interest?

 

[gyraf]

Sounds underwhelming - perhaps because impedance and resulting response and noise figure is all wrong? It's simply not a mic transformer, the input one..

/Jakob E.

 

[[silent:arts]]

Actually the RK204 is a mic input transformer (used in the OV60 and PMV70 mic pres), but in the PV46D it is wired in reverse.

 

[gyraf]

Actually the RK204 is a mic input transformer (used in the OV60 and PMV70 mic pres), but in the PV46D it is wired in reverse.

..aah THIS piece of information may very well be what we need to get this to take an interesting turn, by taking hints from those dedicated preamps?

In my PV46's btw, the input trafo is a BV110..

/Jakob E.

 

[adamasnan]

In my PV46's btw, the input trafo is a BV110..

/Jakob E.

Same input transformer as PV76 Mic amp?

 

[gyraf]

you're right.. which means that it's certainly not the input transformer being wrong that is the issue..

Perhaps i should dig into this, have a stack of the 46's around and at least a couple of 76's with broken input transformers.. Time for a transplant, maybe..

/Jakob E.

 

[timtom]

Here is picture of the racked unit.

I did some recordings last week with the them as preamps and it sounded great.
I'm very happy them.

 

[gyraf]

nice. looks good with that small label..