In the early 1990's Oliver started to design custom amplifier circuits and transformers around the EF732 tube to "hot rod" Chinese microphones.  His creations were well regarded and ended up in professional studios around the greater Seattle area and gained the nickname of "Oliver's 47-type mod".  Eventually, the design was licensed by Telefunken USA and became the RFT AK47 which received positive reviews.  In September, 2009, the licensing agreement expired and both parties agreed to not renew the license.

Recently, AMI was contacted by Blackspade Acoustics, a company located in Switzerland, to provide them with microphone designs and transformers.  BSA was looking for a quality microphone that could be sold for an affordable price in Europe.  After several discussions, both companies agreed to create a product based on AMI's 47-type microphone mod that would be sold worldwide by either Blackspade Acoustics or AMI depending on the region. 

With this new partnership, Oliver decided to make improvements to the design based on experimentation and techniques learned since creating the original circuit.  The former transformer used with this circuit, the BV47, used a lamination that was a mixture of iron silicate and nickel which created an artificial distortion.  Oliver has designed a new transformer, the BV8LP, as a low profile version of the historic BV8 in order to fit in the mic body which is smaller than a U47.  Using all nickel lamination, the BV8LP is a higher quality transformer that produces a more detailed output than the BV47 with improved low frequency response and clarity to optimize the EF732 tube.  As for the metalwork, we selected the T-11/SYT-1101 platform, as the construction is of high quality and produced with tight quality control. The K17 capsule is custom modified and rigorously tested to ensure consistency from unit to unit. AMI then installs every EF732 tube, BV8LP transformer, K17 capsule and amplifier buffer, and rebuilds every power supply with an 11-position polar pattern switch.  AMI also performs the final burn in and testing on every completed unit before they are shipped to Blackspade in Europe or to our own dealer network.

The finished result is the BlackSpade Acoustics UM17, designed, assembled and tested by AMI.

This unit available now.  List price:  $1299.