Welcome, Guest. Please login or register.
December 15, 2018, 12:15:38 PM
Home Help Login Register
News: Please post general conversations, videos, music, and similar stuff in the "Tips, Tricks and General MCI conversations" section, use the Misc section for any product not listed in the categories, parts or custom projects. Thanks!

+  MCI Console and Tape Machine Forum
|-+  MCI Tape Machines
| |-+  JH-110 (Moderator: brianroth)
| | |-+  JH110C 1/2" Conversion
« previous next »
Pages: [1] Print
Author Topic: JH110C 1/2" Conversion  (Read 301 times)
TonesOnTail
MCI Member
***
Offline Offline

Posts: 203



« on: March 24, 2018, 01:43:53 PM »

Hello all,

I know that this forum is largely dead, but I figured I would give it a try anyway.

I am assisting a colleague with installing 1/2" two track heads on a 110C. The heads are B/C heads, and the repro head has the same DCR as the 1/4" repro head of around 35.4 ohms. When running a brand new MRL IEC1 tape in repro, the 10khz response is -18dB down from the 1khz response. I did a test record as is on a new pad of RMGI 900 after boosting the input gain to set +4dB over bias, and swept tone from 1kHz and up, and discovered the -3dB corner to be at around 2800Hz.

Even though the heads measure the same DCR, and are manufactured for MCI B/C electronics it seems possible that an impedance mis-match is causing the 1/2" heads to act as a LPF filter above 2.8khz. Frequency response is flat up to that point.

So the question is, was there an errata or service bulletin dictating a component change on the audio electronics for conversion from 1/4" two track to 1/2" two track?
Logged

'75 MCI JH16-24 w/ JH114 xport ----- '84 Sony/MCI JH110C-HP 1/4" 2trk ----- '82 MCI JH636-VU-AF
brianroth
Moderator
MCI Freak!
*****
Offline Offline

Posts: 965



« Reply #1 on: March 24, 2018, 03:37:52 PM »

You might try contacting John French at JRF and see if he has any suggestions.

Bri

Logged

Professional audio and video systems design/construction/service/common sense.

Now based in Salina, Kansas

http://www.BrianRoth.com
Pages: [1] Print 
« previous next »
Jump to:  


Login with username, password and session length

Powered by MySQL Powered by PHP Powered by SMF 1.1.11 | SMF © 2006-2009, Simple Machines LLC Valid XHTML 1.0! Valid CSS!