[BC] Mic impedance question...

[Robert Meuser]

Why not examine the schematic of the preamp you do have? It is most 
likely be some opamp design. It may be possible to modify the input 
resistance of that circuit to present the proper load without incurring 
losses. In an ideal world that would be a classic 3 opamp stage balanced 
input with the signal feeding the inverting inputs. That would be very 
easy to optimize.

On 2/7/12 1:19 PM, Glen Kippel wrote:
> O
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> I don't intend to hook my mic up to a 6J7, nor can I afford to buy a bunch of preamps to see which one I like best.  As an example of what I am talking aboout, the Neumann TLM-102 shows an output impedance of 50 ohms but specifies a load of 1000 ohms; the Joemeek JM47a specifies>2000 ohms.  Not 600.  The idea of a dual 1-K pot was to have each side in series so as to increase the load impedance.  Thus, with maximum resistance, there would be a 2.6-K load.  I suppose a couple of fixed 220-ohm resistors would hit the 1-K mark close enough. The pot would enable me to dial in the precise load.
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