Bizaare static noise with Ampex machine and BASF tape

[k brown]

My Ampex F-44 produces a loud, random, snapping/crackling static (NOT tape hiss) only when playing BASF SM468 tape, which sadly is the best sounding tape I've ever used on this machine. The noise sounds just like static electricity.

I degaussed the tape path and heads and it went down slightly in volume. I re-racked the tape and that made no difference. I have several reels and they all do it; as I said, no other tape does this on this machine.

Even stranger, as the tape is playing, the noise gets higher in freq (snapping gets more rapid) and much louder If I place my finger on the spinning capstan (which is also suggestive of static electricity) - a second degauss of the capstan made no difference.

The other thing that suggests static electricity is that the Ampex 900/1200/F-44 macines have a felt (I assume wool) back-tension disc in front of the tape heads. Slipping a piece of paper between the disc and the tape reduces the noise by a couple of dB.

The BASF tapes play perfectly on my Akai GS-4000D.

Did BASF use some sort of unusual polymer in the tape base that make it susceptable to static build up (it's said to be polyester)?

The only thing I can think of to try is grounding the chassis to AC ground (it has an ungrounded power plug); any risk in doing so? Suggested place on the chassis to do this?

If that does nothing, the only other thing I can think of is to replace the felt disc with something like a rolled-up strip of 100% cotton fabric.

It's only the PB head that's affected; recordings on the BASF tape made on the Ampex play just fine on another machine.

 

[Brian Roth]

IIRC from comments on the Ampex mailing list, those machines "don't play nice" with back coated tape. The decks were made in the era when tape had a shiny side on the back.

But, no idea why the problem is only with 468....

Bri

 

[k brown]

IIRC from comments on the Ampex mailing list, those machines "don't play nice" with back coated tape. The decks were made in the era when tape had a shiny side on the back.

But, no idea why the problem is only with 468....

Bri

Yep, Maxell XLI plays quiet as a mouse.

Plus, if back-coating were the culprit, wouldn't it affect the record head as well? As I said at the end of the post, the Ampex does not record this noise onto the tape; recordings made on the Ampex with this tape play without the noise on my Akai. The issue is strictly with the PB head.

But maybe the bias current in the rec head neutralizes the static (if that's what it is) during recording?

 

[ruffrecords]

If it is static then it will couple capacitively to the replay head wiring, and since the replay amp most like is a pretty high input impedance even a small capacitive coupling will cause clicks. The record head is probably lower impedance and driven from a much lower impedance so capacitive coupling will be much lower and very low compared to the record current.

Cheers

Ian

 

[JohnRoberts]

I don't know if anti-static carpet spray would help or do more harm.

I vaguely recall old cheap voodoo ion generators (to clean room air) that might impact the static cycle. Again be careful to do no harm.

JR