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Fostex R8 couple weird channels Recorders, Players & Tape Machines
Old 6 days ago
  #1
Gear Maniac
 

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Fostex R8 couple weird channels

Recently got given an R8 to play around with...I work on a fair amount of lo-fi music so this is pretty cool!

Problem: channel 4 is much darker than the others.

Bigger problem: channel 8 sounds intermittent. Does this sound like an alignment issue? Something else? Never troubleshooted a reel to reel before so any help is appreciated!!

Channel 8 sound sample: https://www.dropbox.com/s/b6nn8dhwhj...l%208.wav?dl=1

Yes I have tried different cables on the in/output sides, no change!
Old 5 days ago
  #2
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ruffrecords's Avatar
First thing to do is thoroughly clean the heads. Use isopropyl alcohol and a Q-tip. Dirty haeds is often a cause of 'darkness''

Cheers

IAn
Old 5 days ago
  #3
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Quote:
Originally Posted by ruffrecords View Post
First thing to do is thoroughly clean the heads. Use isopropyl alcohol and a Q-tip. Dirty haeds is often a cause of 'darkness''

Cheers

IAn
Failed to mention I have already given the tape path a thorough cleaning with 99% alcohol Q-Tips. It had unfortunately not been done in a very long time and the machine had been left dormant with a reel of tape on it for years There was brown (oxide yeah?) absolutely caked and hardened on many parts.

Did you give my clip a listen? Does this sound like something wrong with the tape recording/playback side of things or more like a bad connection possibly inside the tape machine?
Old 5 days ago
  #4
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If it has been like that for many years the stuff can be really hard to get off. Even if it looks like you have got it all off you may not. Years ago I had an old Revox A77 with the same problem. One channel was dull. I cleaned the heads and it did not get better. The second time I gave them a really hard scrub with a Q-tip and plenty of fluid which must have got the deeply embedded stuff off because that channel then worked fine.

Cheers

Ian
Old 5 days ago
  #5
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Hopefully you aren't using that old tape roll. It will likely shed instantly back onto the heads.

The channel cutting out is another symptom of using old used tape. Tape doesn't always wind or rewind onto a spool evenly. As it ages the edhes which stick out will warp and when the tape is played back will loose contact with the heads.

Other things. The tape heads may be work. Look at them. If they are worn flat you have a major problem that can only be solved by new heads if you can find them which is nearly impossible for many decks since they quit manufacturing them decades ago.

Belt/felt tension that applies pressure to the take up or feed reel may slip too much or too little. Worn capstan or idler roller is another biggie.
Worn guides which align the tape is another. The deck may have been run vertically or horizontally causing different kinds of wear. The bushing for the capstan may be worn.

You can also have switch problems or fatigued parts like caps in the preamplifier circuits which often begins to happen after 10 years or so which are changing the frequency responses. Many of the components that comprise the circuits and the mechanics begin to break down too, especially any kinds of rubber or foam. Dirt and smoke can be drawn in and contaminate any electrical connection, pots, switches, relays you name it. The circuit boards likely have trim pots which may need to be recalibrated as the board components age.

I could go on and on. Tape machines are high maintenance units and that maintenance needs to be done by a pro who has the necessary parts to replace. Consider its a low end beginners model you simply wont find many parts available and will likely need to cannibalize other units for parts.

If you plan on using the unit for any period of time I'd suggest you troll sites on a regular basis looking for key items that can fail so you have them when they need replacement. I'd likely start with something like this so you can use it for spare parts. Fostex R8 for parts or repair | Reverb It might even be in better shape then the one you have and you could move the good parts needed over to it to make it work.
Old 4 days ago
  #6
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Quote:
Originally Posted by wrgkmc View Post
Hopefully you aren't using that old tape roll. It will likely shed instantly back onto the heads.
Helllll no I came across ten small reels of sealed Ampex tape for a great deal so been using that.

Quote:
Originally Posted by wrgkmc View Post
The channel cutting out is another symptom of using old used tape. Tape doesn't always wind or rewind onto a spool evenly. As it ages the edhes which stick out will warp and when the tape is played back will loose contact with the heads.
Can this happen to tape that's still sealed as-new in the box?

Quote:
Originally Posted by wrgkmc View Post
Other things. The tape heads may be work. Look at them. If they are worn flat you have a major problem that can only be solved by new heads if you can find them which is nearly impossible for many decks since they quit manufacturing them decades ago.
Due to my sheer ignorance are there any images that show a new tape head vs a warn one, or can you describe what I should look for?

Thanks for all that information, really big help!
Old 4 days ago
  #7
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Quote:
Originally Posted by ruffrecords View Post
If it has been like that for many years the stuff can be really hard to get off. Even if it looks like you have got it all off you may not. Years ago I had an old Revox A77 with the same problem. One channel was dull. I cleaned the heads and it did not get better. The second time I gave them a really hard scrub with a Q-tip and plenty of fluid which must have got the deeply embedded stuff off because that channel then worked fine.

Cheers

Ian
Will keep scrubbing! Thanks!
Old 4 days ago
  #8
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ruffrecords's Avatar
The track 8 snippet you posted seems to go up and down in level in time to the music which points to the Dolby C noise reduction being t fault. Try recording on that track with the DOlby switched off (there is a slide switch for this on the top near the RCA connectors.

Cheers

Ian
Old 4 days ago
  #9
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Quote:
Originally Posted by ruffrecords View Post
The track 8 snippet you posted seems to go up and down in level in time to the music which points to the Dolby C noise reduction being t fault. Try recording on that track with the DOlby switched off (there is a slide switch for this on the top near the RCA connectors.

Cheers

Ian
Dolby was off for this test. Although I don't think it's working correctly on this machine. Dolby on for playback reduces the high-end and hiss, Dolby on for recording doesn't seem to do anything: I tried recording something with Dolby off and with Dolby on. Playing both back with Dolby off sounded the same. I was expecting recording with Dolby C on and playing back with Dolby off to sound blown out in the same way as recording with DBX on then playing back with it off on a Portastudio.

Anyway that's a bit of a tangent but I assume this means that it's just not recording with Dolby at any point so it's probably not this?
Old 4 days ago
  #10
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Quote:
Originally Posted by Teej View Post
Anyway that's a bit of a tangent but I assume this means that it's just not recording with Dolby at any point so it's probably not this?
I think you are right. If it is the same on all channels it may just be the Dolby on/off signal from the switch on top not getting there. However, Dolby is not so aggressive as dbx so if you record at a high level Dolby basically does nothing. It only boosts low level high frequencies on record. Even so I think you would have heard a difference.

I have not looked inside my R8 for a long time but I seem to rememeber each channel is on a plug in board. Often the connections to these get tarnished over time and unplugging each board and plugging it in again a few times can often fix quite a few problems.

The first R8 I had had a problem on track 4 which was intermittent. This turned out to be a broken trace on the main PCB which I fixed by bridging the break.


Cheers

Ian
Old 4 days ago
  #11
Gear Addict
 

I honestly can't tell whether or not the artifacts on the recording you posted are in time with the music or not . . . I think it may seem that way to me simply because I think it actually sounds pretty cool like that.

But here are three suggestion to help figure out what's going on:
- If you haven't tried recording with tape from a different source or batch, this is a required step. Tape has a finite shelf life, and even if sealed from the factory, the storage environment greatly affects this.
- Lay the machine down and carefully observe the tape as it's running through the path . . . there should be no drifting side-to-side and no puckering in any way as it moves. Look at any tape guides that were obviously manufactured with round (convex) guide surfaces and inspect for wear . . . even if you're unsure of how the heads themselves are supposed to look, with fixed round guides it's usually pretty obvious how they looked when new.
- Record some music only on the odd tracks . . . then flip it over to run it backwards and play it back, now on the even tracks. You can also do this between between i.e. tracks 1-4 and play them back in reverse to get 5-8. From here you can deduce whether the problem is specific to record or repro (this is a two-head machine, right? i.e. no sync mode). You might not get perfect isolation between adjacent tracks when you do this, but it'll help get an idea if the problem is always present on certain physical tracks of the heads.
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