Question about calibration

[leddy]

Hey folks.

I've got a couple of Tascam 22's, and I don't think the factory calibration has ever been messed with. Works perfectly with Maxell UD35. I decided to set one up for LPR35, since it's been getting harder to come by the Maxell.

When I began the process, I noticed I was getting the "rocks tumbling" sound unless I adjusted the bias to its near-maximum setting. Recorded some tones at all different frequencies and just listened while I changed the bias. I was getting a bump in the high end as well. Long story short, I can't flatten out the high end without getting rocks tumbling. I have to crank up the bias and have a dull top end. Or I can get a flat top end but with rocks tumbling. Can't have both.

Is the +5 LPR35 just too much for the Tascam 22? The rolled-off high end sound is actually not bad. It's really flat up to about 8k (at 15 ips), then rolls off almost like a cassette. Sounds nice and warm, but it's not my preference to keep it this way. 7.5 ips is unusable like this.

Seems like I should not be asking too much of the Tascam to handle LPR35...

 

[Tim Gillett]

"Rocks tumbling" sounds a bit like a magnetised tape path. Have you demagged the heads, guides and capstan shaft?

Tim

 

[jpmorris]

Insufficient bias often produces a noise referred to sometimes as 'bias rocks'. Setting the bias is often something of a compromise between rocks and cut HF unfortunately, but you shouldn't have to turn it up that high - it should be able to handle a 10Khz tone.

What this might mean is that the electrolytic capacitors are sufficiently bad as to be preventing the bias circuit from working properly. I remember that my Studer became a lot easier to bias after I recapped the audio cards.

 

[leddy]

It really feels like insufficient bias as opposed to having to demag. Though I can give that a shot.

I don't have the experience (or time) to recap the thing. I'm sure it would cost way more than it's worth. Maybe I'll try some other tapes with it. Thanks.