Otari MX-50/55/5050 'Master Recorder' Information

[ironbut]

Hi Louis,

Welcome to the forum.
I can't recall seeing a quarter track record head on an MX5050. You probably already know that a quarter track playback head was available as an option for the BIII and most of the earlier 5050's came stock with one. I don't doubt that you could find a 1/4 track or 4 track record head that would fit in a spare headblock.

I'm not sure if you could simply change the headblock to record from a 1/2 track to 1/4 track and still get optimal performance. I remember when I switched an A77 I had back in the 70's, from a quarter track to half track, I had to change some components in the record circuit (I think one was the bias oscillator). I'd think that you'd have to make adjustments at least.

[uraldurusu]

Hi,
I am planning to buy an OTARI MX-5050 BIII but I found an MX55 and the seller send me the pictures of the machine. I didnot see any bias, eq adjustment switch like 5050 on the front panel. How the bias, eq adjustments are made on MX55 ? I've checked the OTARI web site for discontinued products but there is only a presentation of the deck. Any information will be appreciated.

Best regards.
Ural

[ironbut]

Hi Ural,

Don't worry, all these machines capable of recording have bias and eq adjustments somewhere. It's actually unusual for a machine to have fine adjustments on the front panel. Many have switches for "pre-set" adjustments but it's best to have these presets adjusted internally to the exact tape you plan to record with.
I always advise guys who aren't veterans of magnetic tape to take their machines to a qualified service tech and have it cleaned, lubed and adjusted (which includes bias and eq to a current production tape, RMGI or ATR Magnetics). This will give you a baseline for how the machine works when everything is right. Otherwise, if something doesn't seem quite right, how will you know if something is wrong?
Most of the adjustments don't need regular adjustments. If your machine is adjusted to the tape you wish to use, it's very likely that it doesn't need adjusting. If it isn't and you have someone with all the equipment to do the adjustments for you, you'll probably never have to do it again.
The only adjustments that will need adjusting are the heads. Because of the normal wear experienced by the head surface as well as the guides, minor tweaks of the head adjustment are needed over the life of the heads.
If you haven't already and you are new to magnetic tape, check out the "Beginners Guide" located in a sticky above the General Forum.

In the meantime, you can download the service manual and schematics here (free after you register with the site).

http://www.hifiengine.com/library.shtml

[uraldurusu]

Thank you Steve. I am familiar to open reel decks I have a Technics RS1500 and ordered a tape path modification kit. I can do only this kind of mechanical things but not the electronics. I have also calibrated the Technics according to RMGI tapes it is good when the bias and eq at 2/2 position. 1500 has at least 3 modes for bias and eq. But 1520 have fine tune knobs additionally to these 3 modes.

Regards.
Ural