Messages

1

Tape Tech / Re: revox b77mkII

« on: October 25, 2009, 08:31:55 PM »

If you demagnetize, it helps to have  a bit better demagger than the entry-level black ones with the red tips...

Anyway, you need to start with the demagger a metre ( or yard..) back from the head or guide you're going to demag.

Switch it on and bring it slowly into the target, move it gently up and down the head ot guide several times, and then slowly withdraw it back to where you started before either switching it off , or moving in to demag the next head or guide. Do NOT wave the demagger from side to side in front of the headblock assembly...this would not be good...:-)

I note that what  you're hearing is not  tape hiss as you dont hear it when the tape is played, only when you enter record.

The other thing that can cause (additional..)  hiss is problems with the bias signal which is fed to the record head. Bias setting is a compromise between noise and HF response, and you could have a misaligned bias setting, or a noisy bias oscillator maybe. Or even an incorrect HF eq setting or noisy record amp. I have very little experience with Revox, and that not for years  ( although 34 years experience with pro studio tape machines..) and  can't remember offhand about where the alignment stuff is.


The other thing is a possible level mismatch between the MOTU and the recorder. From memory the B77 isn't a +4dB line level machine (  although I could be remembering incorrectly..)  Maybe your MOTU is putting out +4? You don't say which  MOTU you have.

Best regards,

Gwyn

2

Reel to Reel Tape Machines / Re: Anyone familiar with the Sony MCI machines?

« on: October 25, 2009, 07:45:58 PM »

The biggest problems with the MCI JH-24 and JH-110 machines come from the Molex connectors. The flux used to tin the Molex pins at manufacture reacts with the flux used in the MCI solder joints attaching them to  the PCBs. Lots of joints will go cold, and you'll see circular cracks inside the solder roundels, so the evidence is visual as well.

If you remove the transport cards from the motherboard, and then pull off all the Molex connectors at the rear of the board, you can then unscrew the securing screws and get the motherboard out. At that point you take off the old solder with a desoldering pump etc before re-soldering them.  Don't just touch up the old joints.After re-assembly the transport usually goes like a Ferrari..

The JH-24 machines are great for fast multitrack overdubbing ( unlike the Otari MTR-90 which slows to a crawl at it approaches the locate point...) and the remote and locator are great

I found  both the 2" and 1/4" MCI machines very reliable. Bulbs would need changing on the VU's, there would be occasional PSU faults, and we had to have the tach drives replaced once on the 24 track ( quite a skilled job...). Also the interaction between the alignment pots means an inexperienced person trying t align a machine may assume there is a problem when eg the bass end alignment controls have no effect after they've attempted a machine alignment. This can be rectified by centring the multiturn pots and aligning again ( usually 3 times...)

They have ceramic capstans, which in the UK we cleaned with GIF cleaner, whilst being careful not to let any get into the capstan bearing.

There is an optional Logic Annunciator card you find on a lot of those machines - makes transport logic problem diagnosis a little easier.

I used a JH-24 and a couple of stereo JH-110 ,machines for 5 years or so, partnered with a Trident Series 80 mixing console. This was a good solid sonically-reliable partnership , without producing "oh-wow" sonics.