Wednesday, December 19, 2018

Grampian DP6 ?


See updates at the end of this listing. What follows is a systematic error.


Badge is missing. It should be a Grampian DP4.


Initially it was thought it is not working. It was directly connected to Sony TC-D5 Pro. Extremely low output. DC resistance was measured 150KΩ. So is it a very high Z or bad contacts?


It was connected to Pleiades K117 JFET as follows:


DP6 H - Pleiades K118 with 1.3V battery - Sony TC-D5 Pro - Sennheissr HD580


Pleiades K117 JFET has a RedGreenRed source resistor bypassed by 22μF. A RedGreyRed drain load resistor and after it a 1μF coupling capacitor to Sony mic in etc. there is a series 47nFcapacitor to gate.


It worked. Nice no bass heavy sound. It fully modulates VU meters but it could be more sensitive.


Later addition:


The next day it worked brilliantly. It is low Z after all.


It was just stepped up by a Western Electric transformer of 1:2 ratio and then feeding the Sony TC-D5 pro. Amazing sound. Natural and full of everything without exaggeration. Sends for tea so many expensive mics. Most of them?


See also next day's post.








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