feedback when bouncing to adjacent tracks?

[bloomboy]

When I bounce tracks on my tascam 38, if the destination track is directly adjacent to any of the source tracks I can barely turn it up past -20 or so or i'll get this strange high-pitched feedback like sound that suddenly oveloads all the VU meters. Same thing happens if it's two tracks away as well, but I can turn it up much louder before it does so this isn't really an issue. Is this just something that I have to watch out for and deal with, or is there a way around it?

[BRDTS]

This is the nature of analog recording. For bounces, A safety track must be between..ie..you fill 6 tracks, bounce to trk 8. Track 7 is the safety track.

If it were a 24 track, same thing. Fill 22 tracks, leave 23 open while submixing to 24.

Alternatively, you could fill 8 tracks and then record them into an entirely separate machine and then move back and forth between machines that way.

When a recorder is put into record ..with a feed from it's own playback head or the commmon rec/play head....the level at the record head that is "burning" the audio onto the tape, is so high in frequency content, that there is bleed. Put a track into record next to a track that's playing, a loop is set off and feedback occurs. On content that's loud or dynamic enough, you sometimes even have to leave 2 safety tracks between. Not because of squeal, but because of crosstalk.

As you've found out, keep the volume low enough and you can sometimes get away with a bounce. But then your levels aren't very good.

[Herm]

No its not a saftey thing cause you are to close to the track. It is a monitor mixer problem. You have got some wiring or a switch in the wrong place.
You need to check how you are monitoring things.

Make sure you are monitoring only the track you are boucing to.

[bloomboy]

Wow. Well, now at least I know that it's for sure one or the other
I don't think it's a monitor/mixer problem though; I was really careful to only monitor only the destination track. I even tried several different mixers. I did make one useful discovery though, which is that by bouncing a track with no audio on it (i.e. only tape hiss) to the one next to it you can get a transistor radio-like squeal, and you can control the pitch by adjusting the volume of the source track. make sure the level on the destination is set real low though, or you'll be in for quite an unpleasant surprise- maybe even a new pair of monitors.

[bloomboy]

Wow. Well, now at least I know that it's for sure one or the other
I don't think it's a monitor/mixer problem though; I was really careful to only monitor only the destination track. I even tried several different mixers. I did make one useful discovery though, which is that by bouncing a track with no audio on it (i.e. only tape hiss) to the one next to it you can get a transistor radio-like squeal, and you can control the pitch by adjusting the volume of the source track. make sure the level on the destination is set real low though, or you'll be in for quite an unpleasant surprise- maybe even a new pair of monitors. Also, if you record a warbly synth tone to the destination track and then do this, the two sounds interact in a really complex and interesting way.

[Herm]

I still think you have something hooked up wrong. We need another opinion here from a expert like Tim and Jeff or Dave.
I have been doing this on 4 tracks for years and never once had feedback from mixing down to a 4th track with the other 3.

[Beck]

I worked with an Otari 8-track years ago that would feedback when bouncing to adjacent tracks. Yes, some machines will do this. I’m not certain about the 38, but if you’re getting feedback two tracks away, that sounds like a problem.

My TSR-8 doesn’t have these sort of crosstalk issues because of the onboard dbx NR. No guard band is really needed for bouncing or sync track… yet I still don’t bounce to adjacent tracks because I learned not to as a youngster.

It can be better or worse depending on the condition of a machine. Mechanical alignment is very important. You should get an idea of the crosstalk situation on your particular 38. If you record something on track 1, and playback just track 2, how loud is the signal?

I know that’s not a scientific way of measuring crosstalk, but it will tell you if things are wildly out of calibration. You should only hear a faint signal on 2 compared to the signal on 1 if everything is in line. If you hear crosstalk two tracks away a head alignment is a good idea.

I would also double-check your mixer settings, because it could be system feedback, like Herm said. All it takes is one button in the wrong position.

Another possibility – the previous owner of your 38 (if there was one) had the machine setup for hotter tape. Overly hot flux levels will worsen any crosstalk/feedback issues.

~Tim

[MCI2424]

Originally Posted by bloomboy

When I bounce tracks on my tascam 38, if the destination track is directly adjacent to any of the source tracks I can barely turn it up past -20 or so or i'll get this strange high-pitched feedback like sound that suddenly oveloads all the VU meters. Same thing happens if it's two tracks away as well, but I can turn it up much louder before it does so this isn't really an issue. Is this just something that I have to watch out for and deal with, or is there a way around it?

The narrow format heads do this on every single machine made. The best advice is to stay away from bouncing adjacent tracks OR try to keep things like 2 tracks or drums (ch 1&2) and bass guitar (ch 3) bounced to ch 4.

Low frequency content keeps the feedback to a minimum.

The pro machines have wider heads and a better design with electronics that have very high headroom compared to consumer decks.

[Herm]

I still say he has a routing problem. -20 on the mix and gets feedback?

[bloomboy]

Sorry it took me so long to respond- I've been out of town for the last couple of days. It's not a routing problem for sure (it even happens patching one output of the recorder directly into an adjacent input)

I'm going to get it checked over by a tech when I get back. I probably should anyway since it just shipped in about a week ago.

[Track Rat]

I'm with you Herm. Sounds to me like you've set up a feed back loop.

[Herm]

If I get time tommarrow Im going to try this on one of my 38,s and see what happens. Maybe we can figure something out here.

[Herm]

If I get time tomorrow Im going to try this on one of my 38,s and see what happens. Maybe we can figure something out here.

[BRDTS]

Bloomboy-

Plug in the random words adjacent-track-bounce on google and you can do quite a bit of reading of how this affects all machines. It's just the nature of the medium. Owners from consumer formats to MCI users to..well even Roger Nichols comment on the issue. It's one of those first things you learn about in analog recording.

As mentioned in a pretty lengthy discussion starting on page 20 of the TSR-8 (a newer model from your machine), ping-ponging/bouncing/collapsing are most likely going to cause major feed back if attempted to adjacent tracks.

You can certainly do a bounce by finding the absolute lowest level at which the bounce will happen without triggering feedback...but do you really want to end up with your bounced track so low in level that it barely registers on the meter? Plus in my experience, there's going to be garbage in that signal anyway. The time you'll finally hear it is when you eventually run the playback of that track at a higher level at mix. Which is too late to do anything about because no doubt by then, you already erased the original tracks you made the bounce from.

As an alternative....if you have even the most remote feeling that you'll want to haul these tapes out in 20 years and do something with the songs on whatever new whiz-bang technology exists then, you might want to rethink the concept of submixing to one machine track anyway....

A more flexible way for you to submix...and preserve your individual tracks for whatever future need you may discover...is to submix to a second machine. Then route that back to a single track of your 38 (further up the tape where the tape is blank). And then continue building your song that way back & forth.

As it is now with your approach, if you submix and then erase your earlier tracks to free up tracks...those individual tracks are gone forever. Which might be an issue for you 20 years down the road when you decide to remix.

[bloomboy]

Yeah, I am actually working on getting a second 8-track at the moment for more overall flexibility. I've thought about maybe ping-ponging between the two machines, but for me it's a tradeoff between having more flexibility down the road vs during the final mix. A lot of the stuff I do requires me to fade in/out specific tracks during the final mixdown, and if I ping-pong I'll have to do this during each bounce instead. So if I decide I want to balance the levels differently or fade a track in or out differently at the final mix there's nothing I can do, which would be bad, because a lot of those balance decisions have to be made in context of the rest of the song in its entirity. if that makes sense.

I googled those words and found a few really helpful articles. I'm still going to get the machine checked over by a tech though.

[Muckelroy]

I had the same thing happen to me with a Teac A-3440S. I was doing a bounce from tracks 1-2 to track 3, and I could only record up to about -10 before cross-whine occured, basically a feedback loop because of crosstalk between tracks on the tape itself.

It is possible. That's why a guard track is necessary for bounces. You can do it like I did the first time, but your levels need to stay pretty modest.

-callie-

[Beck]

We’ve identified adjacent track feedback and signal routing as possible causes. To reiterate, I think its important not to assume either, but to discover the true cause or causes. Thus, I think Herm’s input is valid even though I may vote for sync oscillation.

Even so, feedback oscillation can be better or worse depending on how close the machine is to factory spec (including head wear). As I stated, I have personally had no adjacent track feedback on my TSR-8. The phenomenon is frequency and level dependant, and can be exaggerated by poor alignment. It may always be there on many, if not most decks, but it can be better or worse depending on certain variables. IMO, sync feedback two tracks removed is pretty bad, and hopefully this can be remedied by a capable tech.

~Tim

[EDAN]

Originally Posted by bloomboy

Yeah, I am actually working on getting a second 8-track at the moment for more overall flexibility. I've thought about maybe ping-ponging between the two machines, but for me it's a tradeoff between having more flexibility down the road vs during the final mix. A lot of the stuff I do requires me to fade in/out specific tracks during the final mixdown, and if I ping-pong I'll have to do this during each bounce instead. So if I decide I want to balance the levels differently or fade a track in or out differently at the final mix there's nothing I can do, which would be bad, because a lot of those balance decisions have to be made in context of the rest of the song in its entirity. if that makes sense.

I googled those words and found a few really helpful articles. I'm still going to get the machine checked over by a tech though.

Since in the end everything goes to digital anyway, until you find the problem you can always record out to CD and "bounce" back to a couple tracks on your 38, freeing up the remaining tracks. There is virtually no real world quality loss, try it you might like it.