Old reel to reel: this is interesting......

[antispatula]

So I've got this really really ancient recorder, looks like one of the first ever made. The sound is so sweet. But after like 20 minutes, the sound gets terrible. Is this just because it's old and gets overheated quickly?

[reel buzzer]

First before you freak out.
turn every knob - from left to right - pots may be not in use for a while
really - I mean crank a guitar signal turn the knob all the way up and down real fast

check for corrosion on the connections

plug it into other monitoring system to make sure its not your mixer

[antispatula]

yeah, I've tried all of that PLENTY of times. Then I tested it after the reel had been on for 1 hour, it sounded terrible. Then I turned it off for hours, and when I tried again, it sounded great. It's not big deal, it's a mono recorder, I'm not using it for anything seriouse.

[Wil Davis]

Are the heads clean? If the tapes are really old, and have not been stored under ideal conditions, the binder which holds the oxide onto the backing tape will tend to absorb moisture, which causes the tape to shed oxide, which sticks to the heads. This might be the cause of the problem you are describing.

The Cure:

1) Clean the heads.

2) Bake the tape (about 2 hours at 154ºF) (!!!) Yep, I'm serious - check threads passim - do a search on "Tape Baking" - either here or on "Google" - you'll learn more about restoring tapes than you could have ever dreamed of…

Good Luck -

- Wil

[Tape Phreak]

Sounds like something's getting too hot to me. Any way to try running a fan on that thing?

[tamky]

Originally Posted by Tape Phreak

Sounds like something's getting too hot to me. Any way to try running a fan on that thing?

I agree. The time factor makes that a plausable explanation. If it were the heads, you'd get shitty sound right away, 100% of the time. This recorder isn't old enough to have any vacuum tubes in it, does it?

[The Ghost of FM]

Originally Posted by antispatula

So I've got this really really ancient recorder, looks like one of the first ever made. The sound is so sweet. But after like 20 minutes, the sound gets terrible. Is this just because it's old and gets overheated quickly?

The first tape recorders ever made and made to sound decent was way back around world war two, in the mid 1930's to the early 1940's.

Are you serious at all about its age or does it just seem that way to you because you don't really know older gear on a personal level?

In any event, a run away thermal event is absolutely occurring here and whether that be a tube or a transistor that has lost its atomic balance with its universe. It must be hunted down by a qualified serviceman who knows what he's doing.

You've told us really nothing of any certainty with regard to the make or model or factual age so I expect the advice you receive here will be equally as vague and vacuous.

Cheers!