MX-70 strange "wind" noise

[barrett]

I was in the middle of my session this weekend when I was noticing an intermittent "crunchy sound" on the floor tom track. I swapped out the card and found that I couldn't recreate the problem but I noticed a strange "wind noise" sort of sound while monitoring the Reproduce head. It seemed to occur upon entering record and continues for a minute or so. I tried cleaning the heads again, swapping the card once more and still, no resolution. edit: I should mention that I tried several different locations on the tape. I don't believe it has anything to do with the tape itself.

Does anyone have any insight in to what might be going on here? I rechecked it several times and it seems to still be happening.

[armanbohn]

I was on this board about 7 years ago discussing the same phenomenon.

I called it SPACE GHOST. It has something to do with bad caps on the channel cards ... use the search function and you'll get some old posts.

[barrett]

I replaced the channel cards and the sound remained. It doesn't occur on any other channel. The channel that I was recording on was swapped out for another channel. The sound remained on that channel. It did not follow the card.

I did find one reference to the "wooshing" / "wind" sound in this post by xonlocust

let me know if you run into any problems. i had TONS when i first got mine, and ended up rebuilding most of the audio cards. they're prone to a "whooshing" sound that sounds like wind on a microphone.

but that's it. I'll try PM'ing him.

[armanbohn]

When you say the sound remained, do you mean the recorded sound? Or do you mean that every time you record, the sound is created no matter what card is used.

The sound gets recorded to tape, so if you switch the card after it gets recorded, it won't matter ... you'll still hear the sound ... it will always be in the same spot and sound the same no matter what card you throw in there.

Before this board died years ago, Xonlocust and I had the initial discussion about this ... those posts were lost with the TapeOp board V1.0 . Xonlocust championed the cause and remained here and posted often about Space Ghost and the MX-70.

Tracking that person down would be a good idea!

[barrett]

the sound re-occurs every time i go into reccord while monitoring repro regardless of which card I place in that slot. It is specific to channel 12 not the card that is located in that slot. I'm heading down there today to check it out again. I pm'd him he's also conviced it should be the relay issue. I'll get more info.

[JohnDavisNYC]

are the bias cards seperate from the record cards? did you try moving the bias cards? sometimes there are issues with tape machines that are a continual bitch... channel 8 on my studer a80 has had problems for 6 years... dan zellman has ALMOST found the problem... by rebuilding the ENTIRE CHANNEL over the last 2 years, and there are only like 3 components that are original at this point, so it better be one of those!

john

[lacquer_monkey]

Do the channel cards have relays with clear plastic tops? If so, they are unsealed relays which are subject to oxidation of the contacts over time. The cure is replacing all the relays in the audio path, on all channel cards.

edit: using sealed relays, of course...

[barrett]

Get this, you're right. Probably anyway. Purely by chance the cards that I was swapping out with each other BOTH have the clear plastic relays. All the other cards are original. They have the sealed ones. I think that's it. Thanks for persisting. I plan to replace the relays.

[TapeOpLarry]

When I had an MCI JH-16 the relays were ALWAYS an issue! Buy a bag of them and replace whenever. How fun.