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HELP! Loss of high frequencies 4 track?
Old 8th November 2013
  #1
HELP! Loss of high frequencies 4 track?

Hi there,

Me and a mate are doing a session, but we keep hearing dropouts in the high frequencies when listening back off my 4 track teac a3440. Its not on the recording, its comes in and out randomly , but it seems that there is more loss of high freq's on the outer tracks, in fact the highs seem to have been lost quite significantly on one of the outer tracks we just recorded onto now.

Could it be the alignment of the heads has gone out? We are doing a session so any help would be great! Have cleaned the heads and demagnatized so ivthink that's not the issue here...

Thanks
Old 8th November 2013
  #2
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Quote:
Originally Posted by dillweed4 View Post
Hi there,

Me and a mate are doing a session, but we keep hearing dropouts in the high frequencies when listening back off my 4 track teac a3440. Its not on the recording, its comes in and out randomly , but it seems that there is more loss of high freq's on the outer tracks, in fact the highs seem to have been lost quite significantly on one of the outer tracks we just recorded onto now.

Could it be the alignment of the heads has gone out? We are doing a session so any help would be great! Have cleaned the heads and demagnatized so ivthink that's not the issue here...

Thanks
Most likely is the tape is shedding, and/or the heads need to be cleaned and/or demagnetized.

What kind of tape are you using?

I know you said you've done it, but if the tape is shedding badly, you'll need to do it again. also could be it wasn't cleaned enough if it's been sitting awhile. give the heads (and entire tape path EXCEPT the rubber roller) a GOOD cleaning with Q-tips and 91% alcohol. If you have a demagnetizer, run it over the heads (without touching them) slowly (don't turn it on or off near the heads) a couple times over. that should cure the problem in most cases, unless the tape is bad.
Old 8th November 2013
  #3
IM using a reel of RMGI tape quite new - there's a bit of residue but not huge amounts.
Old 8th November 2013
  #4
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sadly, my money's on the tape. I've had the exact same issue on the outer tracks on RMGI 911. I even had to transfer a reel lightly holding a piece of cloth to get a decent transfer.

There are a few different theories for this. Personally, I think the tape is defective or just sheds a lot and doesn't work well with narrow-format machines. RMGI says the slitting is slightly different from the Ampex/Quantegy and 3M formulas that came before, causing wear patterns than don't line up the same with the RMGI tape. The Teac decks like the 3340 have a tape path that 'scrapes' a little bit more than it should, so this theory may be correct ... but you don't see these problems with other tapes.

When I had this problem, you could not see actual brown gunk ... it was more like an oil.
Old 8th November 2013
  #5
When i demagnitized today i did very briefly touch the guide on the right of erase head, but that was foe a split second and my demagger has a plastic shield so i cant imagine that would do anything right? High frequency loss was occuring prior to that as well.

Hmm, its strange though, because when i recorded a track yesterday, the highs were there nice and clear on outer channel of the 4-track, but still with occasional dropouts on channel 1 on the 4-track. Now when i play that track back the whole thing seems to have lost the highs and it sounds muddier. IM going to run it through my friends tascam 388 and see if the highs are there i think?
Old 8th November 2013
  #6
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Quote:
Originally Posted by dillweed4 View Post
When i demagnitized today i did very briefly touch the guide on the right of erase head, but that was foe a split second and my demagger has a plastic shield so i cant imagine that would do anything right? High frequency loss was occuring prior to that as well.
that shouldn't cause problems, don't worry about it.

Quote:
Originally Posted by dillweed4 View Post
Hmm, its strange though, because when i recorded a track yesterday, the highs were there nice and clear on outer channel of the 4-track, but still with occasional dropouts on channel 1 on the 4-track. Now when i play that track back the whole thing seems to have lost the highs and it sounds muddier. IM going to run it through my friends tascam 388 and see if the highs are there i think?
Find a different reel of good tape (like Quantegy-branded or Scotch 206), and I bet the problem will be gone. Though the 388 is a gentler transport, so it may actually be okay there ... though that's an even more narrow-format.
Old 8th November 2013
  #7
Well i just played it back through the 388 and hey! All the freqs are the and it sounds forkin great - bad thing is that means there's something wrong with my machine! ****. What could it be then considering the tape is playing fine on another machine?

Cheers - really appreciate the help!
Old 8th November 2013
  #8
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Quote:
Originally Posted by dillweed4 View Post
Well i just played it back through the 388 and hey! All the freqs are the and it sounds forkin great - bad thing is that means there's something wrong with my machine! ****. What could it be then considering the tape is playing fine on another machine?

Cheers - really appreciate the help!
I still think it's the same thing -- probably the slitting vs. the wear patterns, combined with the shedding. try a different tape on your 3340. the 388 is very gentle compared to the 3340.
Old 8th November 2013
  #9
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Did you clean the heads?
Old 8th November 2013
  #10
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Did you clean the heads?
Old 8th November 2013
  #11
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Quote:
Originally Posted by dillweed4 View Post
Well i just played it back through the 388 and hey! All the freqs are the and it sounds forkin great - bad thing is that means there's something wrong with my machine! ****. What could it be then considering the tape is playing fine on another machine? !
your machine has both a record head and a playback head. They are separate entities. They are aligned separately with their own screws.

your record head could be fine and your playback head might be out of alignment, (or worn down, dirty, gummed up, or magnetized) and you would be able to make a good recording. Just not play it back accurately. Or play anything back accurately for that matter. But you could easily make a recording that sounded good on another deck.
Old 8th November 2013
  #12
Quote:
Originally Posted by superburtm View Post
Did you clean the heads?
Of course!
Old 9th November 2013
  #13
So the tape played through fine on the 388 but on the A3440 (my machine) it occasionally lost the high's - still can't figure out why this is.

I gave the heads a good thorough clean and although the high dropouts are less frequent they still occur.

Bad tape? Mis-aligned playback head? Bad connection inside machine? I'm just trying to think of all possible causes that I can look into/check -

THanks!
Old 9th November 2013
  #14
Gear Guru
 

Quote:
Originally Posted by dillweed4 View Post
Bad tape?
if the tape plays fine on another machine, how does it "know" to play poorly on your machine? Unless the dropouts occur at the same spot every time, it is probably not the tape.

Quote:
Mis-aligned playback head?
this is my guess and it would be easy to confirm. Just play a tape that you know is "good" - say from your friend's deck - and see if the same dropouts occur on your machine but not on his.

another thing you could try is using your finger to push the tape around so that it makes different contact with the play head. If in your moving the tape you find a position that makes it sound "better", your head is likely out of alignment. It the head is properly aligned, not touching the tape should sound the "best".

when was the last time you aligned the heads?

make sure you also have thoroughly cleaned all the tape guides, as they may also 'push' the tape to ride incorrectly across the heads.
Old 10th November 2013
  #15
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Quote:
Originally Posted by dillweed4 View Post
So the tape played through fine on the 388 but on the A3440 (my machine) it occasionally lost the high's - still can't figure out why this is.

I gave the heads a good thorough clean and although the high dropouts are less frequent they still occur.

Bad tape? Mis-aligned playback head? Bad connection inside machine? I'm just trying to think of all possible causes that I can look into/check -

THanks!
I'm 90% certain it's the reason I stated above --

The 3340 is something of a rough transport that doesn't have rollers. If your tape is slightly goupy (which RMGI 911 has been in my experience), you're going to have more noticeable problems on this deck than others. This is exacerbated by the potential that your 3340 has wear patterns from the slightly different slitting of an older Scotch or Ampex tape. Your 3340 is literally scraping some tape off, and the particles are getting on the play head. This will be much more pronounced and noticeable on the outer tracks AND IT WILL BE RANDOM -- meaning if you wipe the head with your finger and rewind, it will not occur again in the same spot (unless it happened on the record head while recording).

The 388 is a more gentle transport with rollers ... thus the scraping would not occur. Seriously, look at the transport -- the 388 has lots of rollers, while the 3340 has a much larger space (creating more tension) and a static path.

I've owned and used many machines (including both a 3340 and a 388), and it is not unusual for a tape to play fine on one machine and not on another, especially with a (in my opinion) troublesome tape like RMGI 911.

For instance, Scotch 201 is not the most stable tape in the world ... I had a reel that had lots of high frequency loss on my Teac 3300 due to excessive shedding. The same reel worked fine on my Ampex 440.

also, get in there with your fingernails, q tip & 91% alcohol ... through the entire path, every nook & cranny.
Old 10th November 2013
  #16
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I'm with joeq....sounds like the typical loss of high frequency with a bad playback head or poor head wrap. You can check that by lightly pressing the tape against the playback head...you should hear a difference.
But unless you've had the deck properly aligned, you really don't have any idea.
For all you know the playback head is worn and unable to repro high frequencies correctly.
It could be the EQ bias adjustment are off. It could even be old bad caps in the EQ section in the playback amp.
First thing is to get an alignment tape on it and check.
Old 10th November 2013
  #17
I forgot to mention I used a 7" plastic reel of tape running onto a metal 10" TEAC spool - I've heard that's not the best thing to do but I don't have another plastic reel at the moment. Could that mess up tape to head contact?

I bought this A3440 from some guys who used it twice, and then left it in storage. The heads are pretty much spotless - although the RMGI does leave a surprising amount of residue for a new reel of tape! Not good really...

OK I will have to do some more testing with a tape that I know to be good - How about a big old reel of Maxell 50-120? djmukilteo has a point though, I don't want to jump to any conclusions but if the problem isn't gone after tape test I might have to bring it to a tape guy to have a look at for me and check alignment etc...
Old 10th November 2013
  #18
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Quote:
Originally Posted by dillweed4 View Post
I forgot to mention I used a 7" plastic reel of tape running onto a metal 10" TEAC spool - I've heard that's not the best thing to do but I don't have another plastic reel at the moment. Could that mess up tape to head contact?

I bought this A3440 from some guys who used it twice, and then left it in storage. The heads are pretty much spotless - although the RMGI does leave a surprising amount of residue for a new reel of tape! Not good really...

OK I will have to do some more testing with a tape that I know to be good - How about a big old reel of Maxell 50-120? djmukilteo has a point though, I don't want to jump to any conclusions but if the problem isn't gone after tape test I might have to bring it to a tape guy to have a look at for me and check alignment etc...
I would check all those things first. the different size reels and different tape.

Sticky Shed Syndrome (SSS) is a big problem and using new fresh tape is needed to rule that thing out. You should also realize tape comes in different levels too. So use the correct "new" tape recommended for that deck and it's bias calibration. I would think RGMI LPR35 would be a better tape to use for that deck.
FWIW that 911 tape seems like the wrong tape to use with that deck anyway and if it's got SSS then you shouldn't use it at all. It's a hot +6 tape and thicker mil.
There should be no residue left on the heads or guides at all.
Old 10th November 2013
  #19
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Quote:
Originally Posted by dillweed4 View Post
I forgot to mention I used a 7" plastic reel of tape running onto a metal 10" TEAC spool - I've heard that's not the best thing to do but I don't have another plastic reel at the moment. Could that mess up tape to head contact?

I bought this A3440 from some guys who used it twice, and then left it in storage. The heads are pretty much spotless - although the RMGI does leave a surprising amount of residue for a new reel of tape! Not good really...

OK I will have to do some more testing with a tape that I know to be good - How about a big old reel of Maxell 50-120? djmukilteo has a point though, I don't want to jump to any conclusions but if the problem isn't gone after tape test I might have to bring it to a tape guy to have a look at for me and check alignment etc...
That puts more tension on the tape, which would emphasize the problems I mentioned above. There is also a tension setting, put it on the lower one.

I really don't think there is anything wrong with your deck.
Old 11th November 2013
  #20
Quote:
Originally Posted by donnylang View Post
That puts more tension on the tape, which would emphasize the problems I mentioned above. There is also a tension setting, put it on the lower one.

I really don't think there is anything wrong with your deck.
Cool well really thanks for the help man - I may restart this post if problem gets worse and I can't find a solution. I will endeavour to get a 7" plastic empty reel so I can run this **** through properly!!

Otherwise thanks to all
Old 11th November 2013
  #21
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Quote:
Originally Posted by dillweed4 View Post
Cool well really thanks for the help man - I may restart this post if problem gets worse and I can't find a solution. I will endeavour to get a 7" plastic empty reel so I can run this **** through properly!!

Otherwise thanks to all
it should work fine with the 10.5" reel. just set the tension to low !
Old 11th November 2013
  #22
Quote:
Originally Posted by donnylang View Post
it should work fine with the 10.5" reel. just set the tension to low !
Oh cool - considered!
Old 22nd November 2013
  #23
For anyone who is interested, I tried a new reel of Quantegy 478 tape and there doesn't seem to be any high dropouts.
Old 22nd November 2013
  #24
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FFTT's Avatar
 

When you do clean heads, make sure you are using 100% denatured alcohol and nothing with added oils like rubbing alcohol.

I cleaned heads & rollers every session and sometimes mid session just to make sure.

Keep your deck under a dust cover too.

You mentioned certain tracks are losing highs.
You might want to dedicate those tracks to bass & kick placing the highs
on the inner tracks.
Old 15th February 2014
  #25
Hey guess what people who have been on this thread, I finally took my 4-track to the engineer and it turns out the heads were completely screwed! Nothing to do with the tape I was using. Weird as the heads looked fine to me, just goes to show how little I know. Anyway hes going to polish them down for me and Ill get another couple of years from them
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