Mic pre for cheap?

mhelin said:

Just an idea. You can get various headphone amps from Ebay as kits or ready built if you prefer. Many of those have nice Class-A discrete output stage which can driver nicely your neveish output transformer.  Some have an opamp with adjustable gain (using DIP switch). Just add an input transformer and power supply, box it and you have a nice preamp no one else does.

Here is one example, this kit is based to Lehmann headphone amp:
www.ebay.co.uk/itm/YS-New-Headphone-preamp-kit-classics-board-Amplifier-kit-Base-on-lehmann-amp/272205636659

Schematics can be found here:
http://www.head-fi.org/t/501046/the-lovely-cube-headphone-amp-lehmann-black-cube-linear-clone

Just replace the gain resistors with an anti-logaritmic pot or rotary switch to get enough gain (also add a cap in series to avoid noise when adjusting the gain).

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Andy Peters said:

Those aren't microphone preamps.

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mhelin said:

The idea is to modify the circuit so that they will be like one - add an input transformer, an output transformer, a power transformer,  phantom source (could be a cheap DC/DC converter from ebay), add the front end  like JLM Go Between Kit or just an XLR connector, and adjust the gain stages to get enough gain and match the impedances and do all obvious things.

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Whoops said:

Mhelin,  I dont want to slam the idea you brought, it's quite ingenious but
you're talking  about buying an input transformer and output transformer and an £18.50 heaphone amplififer.
With that input transformer and output transformer for £18.50  I can build the Neve 1290 circuit,  pcb and all the components.

If for the same price we can have a Neve circuit why should we modify a heaphone amplifier as a mic pre?

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