RMGI SM911 shedding

jpmorris

jpmorris

Tape Wolf
Over the weekend I've been doing my first recording on 1/2" SM911 from RMGI. One thing that is concerning me is that over the course of the tracking it seems to be shedding a lot more oxide on the heads than 456 would on this machine. Has anyone else noticed this? Is 468 better in that regard?
 
yeah I noticed that too. make sure you clean your pinch quite often. You might have gotten a bad batch if it is shedding bad; what I noticed was a noticible amount more than 456 but nothing that caused any problems.
 
I only have one reel of RMGI SM911 (an early one). Everything else is BASF or EMTEC. None of the 911 I have has any shedding to speak of.

Ironically 456 is one of the better tapes as far as shedding goes... as long as it doesn't have Sticky-Shed. In my experience 499 is the worst. GP9 and SM468 are the best, but everything sheds a little.

:)
 
Guys, is anything in your tape path worn to the point of it actually shredding tape ? :confused:
 

Attachments

  • tn_K_GT_AMC_Grater_890.JPG
    tn_K_GT_AMC_Grater_890.JPG
    59.6 KB · Views: 210
Daniel makes a good point (with a chilling illustration, I might add :eek: ). Everything in the tape path should be as round and smooth as possible. Add turning and maybe polishing and buffing any stationary guides to your maintenance list on an older machine.

You should normally only have to turn and/or deep polish once after you acquire a used machine. It takes a long time for a tape path to wear to the point of being hard on tape and it will take a long time to wear down again once you’ve addressed the problem.

Of course in a busy working studio this will have to be revisited more often, but for the average home or project studio you’re good for years as long as you keep the tape path clean.

This is one thing we haven't talked about much and it’s beyond even most service manuals.

A Dremel tool with a buffing attachment is invaluable here. However, don’t rush in without knowing what kind of metal you’re dealing with. The tools and compounds will be different for aluminum, stainless and chromed parts. This subject would be worth a thread. I’d like to hear what others are doing.

I have all kinds of things in my studio maintenance kit that you might not expect to find, including bumper chrome polish.

It depends on what you're starting with... that is, the condition of your machine when you purchase it.
 
Beck said:
Everything in the tape path should be as round and smooth as possible. Add turning and maybe polishing and buffing any stationary guides to your maintenance list on an older machine.
Click to expand...

This is the interesting thing - the 456 didn't shed on this machine at all. 406 does (which is why I don't use it much) and now it seems that 911 does too. And yes, as soon as I realised it was doing this I replaced the straws on the lifter so the fast wind had a perfectly smooth surface. This did not stop it.

I'm going to rotate all the guides tonight and see if that helps.
 
jp, where is the oxide depositing or at which point is it coming off? Have you checked if the heads have jagged edges? If SM911 is shedding but not 456, on the same machine, then I'd like to know why as well.
 
jp, falken, dk, can you guys post some nice and clear picts of your tape path, after it had been cleaned?
 
OK, I've stumbled onto somethin' very interesting, potentially answering the above question:

http://www.gearslutz.com/board/new-product-alert/117405-rmgi-tape.html

To briefly summarize:

Quantegy and other manufacturers used to "underslit" their tape to cure slitting problems they had.

RMG slits their tape at the "proper" 2" spec.

Because my machine [insert name of recorder] had only run Quantegy most of its life, the wear patterns on the guides and lifters [I add heads to this] would be "undersized" and would damage the edges of the SM911 [or any other RMGI tape]. This damage is microscopic, but is enough to cause the tape to shed.
Click to expand...

It's well known that Quantegy had slitting issues and, if the above is true, and I strongly lean toward it being so, then what a nice legacy Ampex / Quantegy left us, no? :rolleyes:
 
Last edited:
cjacek said:
jp, where is the oxide depositing or at which point is it coming off? Have you checked if the heads have jagged edges? If SM911 is shedding but not 456, on the same machine, then I'd like to know why as well.
Click to expand...
It sheds at every static point on the tape path, and on the capstan too. I'll admit there are flat spots on the tape path and indeed the wear is uneven with the bottom more worn than the top. I'll have to get it relapped at some stage as I've been putting it off too long. The erase head is fine though, and that has been accumulating shed too.

cjacek said:
jp, falken, dk, can you guys post some nice and clear picts of your tape path, after it had been cleaned?
Click to expand...
Clear pictures are not going to be easy to obtain without a good digital camera. It will take a while to do the old-fashioned way.

**EDIT**
I'm gonna compare batch numbers with the known-bad batch mentioned on TapeOp when I get home. If it was just the guides I'd have expected shed at the top and bottom but it's more-or-less evenly spread throughout.
 
Last edited:
cjacek said:
OK, I've stumbled onto somethin' very interesting, potentially answering the above question:

http://www.gearslutz.com/board/new-product-alert/117405-rmgi-tape.html

To briefly summarize:

It's well known that Quantegy had slitting issues and, if the above is true, and I strongly lean toward it being so, then what a nice legacy Ampex / Quantegy left us, no? :rolleyes:
Click to expand...

This is my post from over at gearslutz. I can add some additional info to this.

As an aside, i have run 499 on the machine really hard for the last month and nary a spec nor peel anywhere. As flawless as a 30 year old deck is gonna get.

My machine has rollers except for the flutter arm, guides, heads and lifter. The guides are relieved at the top and bottom and so never touch the edges. The flutter arm is perfect, no wear at all. The heads just came back from JRF and are in fine shape, so that leaves the lifter. That has a VERY small amount of wear on it, maybe a few thousanths at worst.

I would assume that would be the culprit out of all the places tape touches.

I am going to do an experiment, hopefully this week. I am going to put on the brand new SM900 and play it onto an empty take up reel without rewinding it first, then look for shedding. Maybe even repeat this a few times. The idea being to not use the lifter at all. If it does shed, then it is either a bad batch or there is somewhere other than the lifter that is damaging the tape. I am betting that it will not shed.

Assuming no shed, then I am going to rewind the tape some (which brings the lifter into play) and play that section of the tape, and repeat a few times, and again see if it starts to shed.

When the 911 shed, it was immediate and catastrophic, but then again I had rewound the tape to be tails out, so the whole roll had passed over the lifter.

You can look at the tape slitting thing from another prospective. Did ampex/Quantegy leave us a legacy, or a standard? RMG could be blamed for not keeping with "tradition" and under slitting their product a few thou to keep this from happening. Seriously, how many decks out there have run quantegy all their lives and would be up against this problem? I am thinking a majority.

I am not bashing anyone or jumping to any conclusions. I just wanted to put what I had happen out there and see if anyone else is seeing the same thing.
I am still hoping RMG just had a bad batch of 911. It would be easier to deal with, I really would like to use their product and support them.

mm
 
This happened years ago with some batches of Scotch 226, which were known to be a bit wider than 456. Yep, AMPEX 456 is/was the de facto standard, so when manufacturers make a “456 compatible” which 911 originally was billed as, they have to follow the spec rather than redefine it, even if they think they are correcting something.

I don’t know if that’s what happened here or not (just thinking out loud), but if it’s that widespread (no pun intended) it might explain the sudden jump in prices. They forgot to budget for having much of the initial run being returned as defective. Darn! :eek:

It’s funny though; I have a very early run of 1/2“ 911 sent to me for testing. It looks like, smells like, and performs like my older BASF and EMTEC branded 911, and none of them shed. Same goes for the 468. :confused:

Back to the jagged tape path issue… lifters are often the first things to go, depending on design. You’ll see them worn pretty flat on machines that show little wear on the heads and other parts of the tape path.
 
Last edited:
I might add… except for the sticky shed issue afflicting older AMPEX, I’ve never had any bad experiences with AMPEX/Quantegy 456. All of my current stock is 1995-2003.

But bad batches are a fact of life with all tape manufacturers, so there are bound to be glitches.

I ignore the horror stories I've heard for as long as I can remember about one brand of tape or the other, which IMO were started by the competing manufacturers and vendors.

:)
 
marshman said:
You can look at the tape slitting thing from another prospective. Did ampex/Quantegy leave us a legacy, or a standard? RMG could be blamed for not keeping with "tradition" and under slitting their product a few thou to keep this from happening. Seriously, how many decks out there have run quantegy all their lives and would be up against this problem? I am thinking a majority.
Click to expand...

It left us a standard of bad slitting practices. It seems the only machines which are affected by the shedding, assuming as the result of the "underslitting", are severely worn and should have the guides, lifters turned / replaced and heads relapped or replaced anyway.

IMHO, to expect RMGI (or any other company) to support bad manufacturing practices just to be compatible with badly worn tape paths, compliments of badly slit Ampex / Quantegy product is silly.
 
Hey Dan, it’s not really wear due to badly slit tape, but simply one tape is cut wider than the other. When tape wears a tape path it does so to its width, whatever that may be.

Looking at every manufacturer, there are no tapes that are exactly alike with slitting. It can be said that some are a bit to wide, or some are just a bit too narrow… it depends on what one is selling.

I wouldn’t let RMGI or US Recording Media pass the buck on this one to easily.

1) if it is indeed the reason behind the reports of the RMGI shedding, IMO the experienced people they tell us are running RMGI should have foreseen the problem, considering that AMPEX/Quantegy was dominant for so many years and most everyone is dealing with used machines.

2) AMPEX was so well established as a standard that many heads have been designed over the years with relief slots based on AMPEX tape width. Even brand new, these machines would choke on any tape that was far outside these tolerances. Hence the problems years ago with edges actually pealing off Scotch 226. You could hear it and literally see hair-sized lengths of tape being shaved off and falling to the ground. The consensus then was that Scotch had made some batches too wide. When they subsequently replaced 226 with 966 (986) they specified a slightly narrower tape.

Over the years I’ve used 3M/Scotch 226, 966, AGFA/BASF/EMTEC 468, BASF/EMTEC 911, AMPEX/Quantegy 456, GP9, 499, and 406… and only saw measurable edge wear with some Scotch 226.

Going back to earlier conversations we’ve had about tape selection, the tape path was the last thing on our minds. It was all about the character of a given tape and for the most part interchangeability was uneventful. I still work that way… matching tape formulations (choosing the canvas) for the picture I’m trying to paint.

Right now I use 456, 406, 911 and 468 on the same machine depending on the sound I’m after. Even with the most recent RMGI 911 I’m not experiencing any problems. Granted my tape path is unusually clean, but the TSR-8 does have the relief slots in the head for the edge tracks and none of the tapes I’ve mention have any difficulty running on it.

After reading more complaints around the web, I’m wondering if a few batches got out of Holland that were less robust than we’re used to. :confused:

Something else to consider anyway.

:)
 
Beck said:
Hey Dan, it’s not really wear due to badly slit tape, but simply one tape is cut wider than the other. When tape wears a tape path it does so to its width, whatever that may be.
Click to expand...

I was merely pointing to the shedding issue, which most likely results in using a slighty wider (but cut to spec) tape vs the undercut one. As is the case with the slightly wider RMGI tape on a path grooved by the "narrow" Quantegy tape, you get shedding at the edges using RMGI. Basically the undercut Quantegy tape cuts into the tape path overtime and if one sticks to only Quantegy then all is well but if one uses RMGI, which is properly but slightly wider cut (than Q), you get edge shedding off of the RMGI tape (on a machine which ran Quantegy all its life and has tape path wear to show for it).
 
You must log in or register to reply here.
Back
Top