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[bushwick]

Hey there Steve-

That massive "Why Do Musicians" thread has grown a bit out of control so I thought I'd start a new one to address this issue. You got me thinkin with your replies to Erase Current capabilites. So I shot an email over to the head studer tech at Sony here in NY to address the issues and refresh my memory. Here is an excerpt from that email:


"And yes, at +9/185 on an A800, your erase amps are screaming for mercy and are definitely maxed out. Unless you are recording nothing but head banging rock and roll you will always have to deal with some residual signal, which could kill a nice ballad."


So I am confused. I have been educated by three top studer techs, one of whom was trained by Studer in Switzerland, to the specific point of whether or not my machine is functioning properly, including their thoughts on reusing tape stock. As well, I have you, an extremely accomlished audio engineer telling me that this is not the case. Having rebuilt a major portion of my machine - thanks to a shifty deal from England some years ago - there isn't a whole hell of a lot that I can think of left to do to the machine to change its operation. To boot, these fellas seem to think that its okay.

So please, the next time you are in NY, stop by my studio and tell me if I am losing my mind. Hell, I'd love to show you the place, get yer two cents on thangs.

All the best,
joshua kessler
bushwick studio
brooklyn, ny
www.bushwickstudio.com

[bobkatz]

bushwick wrote on Sat, 17 December 2005 13:48

Hey there Steve- "And yes, at +9/185 on an A800, your erase amps are screaming for mercy and are definitely maxed out. Unless you are recording nothing but head banging rock and roll you will always have to deal with some residual signal, which could kill a nice ballad."

You might try seeing if the Erase head's virtual gap is truly centered on the tape. Push down on the left and right side of the tape while erasing and if the sound goes away, then you are into some work adjusting the centering. Unfortunately, you have to remove the headstack and turn the nut on the bottom to recenter a Studer Head, so it's a bit of work.

Disclaimer: I haven't pulled a Studer 24 track headstack in many years, so I may be remembering wrong if the Erase head has a centering (rotation) screw. But I can tell you that the record and playback heads do have them, and they should be adjusted properly during an initial setup or you will not be getting maximum life from your heads! Hint: Very few machines are so adjusted, so get centered!

BK

[bushwick]

Hi Bob-

Intersting. The heads have not had a bunch of use since I drove the headstack over to John French so he could reground them (silver paint in the holes next to the tracks on the heads) and he set up the heads there for me. I know the azimuth survived the trip back home, I never thought to check that out. Thanks for the tip!! It'll take me a little bit here to get to that but I'll let you know what I find.

Best,
josh

[bobkatz]

bushwick wrote on Sun, 18 December 2005 04:37

Hi Bob- Intersting. The heads have not had a bunch of use since I drove the headstack over to John French so he could reground them (silver paint in the holes next to the tracks on the heads) and he set up the heads there for me. I know the azimuth survived the trip back home, I never thought to check that out. Thanks for the tip!! It'll take me a little bit here to get to that but I'll let you know what I find. Best, josh

By the way, for record and play heads, centering, azimuth, zenith, and height are potentially interactive, so prepare for a long session until you get the centering right, but in the end it's really worth it. For the erase head, azimuth is not that critical and you can eyeball it.

The trick on the centering is to leave the screw just a little loose, adjust it, remove the headstack, tighten the screw, and recheck it by touching the left and right side of the head to see if the high frequency response goes up in the case of audio heads, or the erase gets better in the case of the erase head. Use a 20K tone. So as not to waste the MRL tape, you can prerecord a 20K tone for centering purposes of the playback head if you first "roughly" adjust the azimuth with the MRL.

BK

[bobkatz]

Also, on this subject, John French uses optical alignment techniques to ensure that the heads are just right. And the guides are incorporated in the stack. But there are variables of tape wrap and tension and maybe even human variables, so I always do a thorough check and retweak if possible when the headstack gets back here. Especially when it comes to centering, I honestly don't know if John is capable of truly determining the exact centering without having a real tape path. I've seen a playback head that someone thought was failing totally come back to life when the centering was adjusted.

Also note that the old "sharpie paint on the head" technique to see if the tape to head contact lands right in the middle of the visual gap is a good start, but should not be used for the final adjustment. This is because in the record head the virtual gap is not the same as the visual gap. And there's something about rotating a head while viewing the HF response that gives the ultimate sense of confidence.

[electrical]

I've been thinking about this.

Most of the sessions I've done on A800s have either been long ago, on 456 or 468 (where the 500nWb/m issue would be moot) or at 15ips, where erasure is better on every machine. I'm sorry if I jumped to a mistaken conclusion about these machines. I know I had no problem with my A80MKIV, and we have no such problem with our A820s.

I have run into problems on older machines with high-output tape, but the problem is generally in the record EQ, where there isn't sufficient "cut" available for flat 30ips recording. I recently had a problem in a big fancy studio with erasure on an A827, but it was an adjustment problem, not an un-avoidable one.

I find it hard to believe that sufficient drive current isn't available (possibly with a modification to the erase master amplifier with different output devices, if necessary) to erase 30ips 500nWb/m. Seriously, if I couldn't run-over take one with take two, I would stop the session and go elsewhere, and if I owned a machine with that problem, I would do whatever it took to fix it. Spending half my time erasing is simply too much to ask.

I would love to hear a solution to this problem, if it is a general one and not specific to one machine, for A800s. Any modification suggestions welcomed.

[bushwick]

Hey Steve-

Haven't had a chance to check the rotation of the erase head yet - next week. But wanted to clarify the logic here. If I am recording on one piece of tape and one song is thumpin the tape with level, being that the reel is going to record different songs there might be a quiet intro or a fade out on the same stretch of tape where the previous recording had very loud music. Its to that end that i would hate to have some residual bleed pop through and where I would err on the side of being cautious. If I am not recording to one reel over and over then I don't worry about it becuase there is never going to be the risk of that kind of scenario. And for what its worth, I have never had a problem with my machine not erasing properly during tracking.

Happy Holidays to all,
josh

[wwittman]

I must have done 100 records at 15ips on 456 at 500 nW/m with no erase problems.

It's my 'standard' alignment.

and many of them, most perhaps, on A800's or mixes at the same flux level on ATR 102's.

[electrical]

wwittman wrote on Fri, 23 December 2005 18:50

I must have done 100 records at 15ips on 456 at 500 nW/m with no erase problems. It's my 'standard' alignment.

Really? That blows my mind a little bit.

[Larrchild]

Having just repurchased the A800 I spent 12 years maintaining at New River in Ft Lauderdale and installing in it's new studio,  I am anticipating this problem.

When 499 came out, I recall doing a +8/30ips alignment for a client and proceeding to test the '800's erase mettle. Sure enough, after printing a 1k tone at zero and rewinding and punching in with dead air, most faders contained some ghost tone. I peaked everything, erase wrap, trimmers and what would happen is, when that bias led would snap on bright, you were clipping the waveform and putting punch-in tics on the tape.

I am now convinced that some more efficient erase head or some higher voltage erase fets may be the only cure.

I'm lookin into this.


500nw/m..thats some strong magnetism, does the tape jump off the head on the kick drum? No erase probs?
Both my machines did it, But only on 499. I think its higher coercivity makes it harder to erase.

Now ya got me thinkin. WW, at 15 does the tape have more time to pass thru the erase field? hmmm.

[bushwick]

Hi Larr-

Interested in what you find. I have done the erase cal as per the studer manual but find that is not optimal. It works out better for me to just do it by ear. I am not sure why Steve A. uses a 100hz tone pulsed, or rather why a 100hz tone. Steve?

-j

[electrical]

bushwick wrote on Sat, 24 December 2005 14:16

or rather why a 100hz tone. Steve? -j

I've found it easier to identify the LF pulse as a residual when listening through the tape noise.

[wwittman]

I rarely used 499 mostly because I just think 456 sounds 'better' to me.

Perhaps part of what makes this level work for me is that I can manipulate the result by how hard I hit the front end.
I TEND to mostly peak things at around 0 VU (i'm not a Roy Baker meter slammer), and on things with steep transients that I want to preserve, I might run them lower still than that.

So if you align to 0 Vu= 3 over 250 but then you peak your console out levels at +3 or pinned, then you are putting as much level on tape as I am with my alignment of 6 over 250 but signals near 0 Vu.

Part of the decision for me, is that I really like the sound of tape compression on some things, but i DON'T like the sound of console electronics or tape machine front ends being slammed.

But by having that 0 Vu point be 500 nW/m (approx) I have the ability to DECIDE to really push some things (usually guitars) up into the red and really make the tape compress.

It just works for me and it's what I'm used to.

On mixdown, I really try to keep the overall level around 0 with the only occasional bump into the red.


I should add that, before I permanently wised up, I made loads of records at 30ips with that alignment as well... no erase problems there either.
My recollection, for example, is that She's So Unusual (including TIme After TIme and Girls...) was 30ips 500 nW on the 2" 24 track and the same flux level on 1/4" stereo at 15 ips for the mix... both on 456 for certain (I have the Golden Reel Award!)

[Larrchild]

The pisser was that the erase head is a staggered Woleke ceramic head with 2 rows of 12 tracks. So when you peak the erase head wrap, the tones will dissapear on 12 of the tracks and get louder on the other 12!

That said, it was never a prob til 499.
I'll see what John French has to say. The head does not get so warm that more current to it would make it glow red. I think another 10-20v of fet rail would cure this on the erase amplifier circuit.
I doubt these fets are ready for that, so I may take a card and upgrade the fets and run it off of external rails for the test on one channel.

Stay Tuned/.

[bobkatz]

Larrchild wrote on Sat, 24 December 2005 15:35

The pisser was that the erase head is a staggered Woleke ceramic head with 2 rows of 12 tracks. So when you peak the erase head wrap, the tones will dissapear on 12 of the tracks and get louder on the other 12!

I FORGOT about that staggered model on the 24 track... well, wrap, centering, and penetration are three different physical adjustments, some of which are not adjustable on the Studer. Obviously, for a staggered erase head, you want to get the center between the two sections, and have a wrap wide enough to spread across both. Assuming the erase head current has already been optimized; I wonder if JRF or anyone really knows what's the maximum you can pump into that head without damaging those little wires or melting the tape  .

[Larrchild]

Since the whole head mounts and pivots on a single bolt, I may have options. I'm digging for the original Woelke specs before I blow a winding.

Hey didn't reaaly old Studer A-80's have 2 erase heads? I can guess why. Maybe the record head was just to the left of the idler.

[dcollins]

bobkatz wrote on Sun, 25 December 2005 06:58

I FORGOT about that staggered model on the 24 track... well, wrap, centering, and penetration are three different physical adjustments, some of which are not adjustable on the Studer.

A sign of improper rotation of the erase head is the odd or even tracks will have deeper erase....

DC

[Larrchild]

Yep. Equal erase on all ch's means its in the center wrap-wise. Since the whole head is pivoting on one bolt, you have to snug the bolt and turn the head for max then tighten down the bolt. It's a real Swiss-Picnic.

[mr335]

I think it's more common to just tweak the p-ram and reglaze the subroutines.\

And for a little extra gelatine I respindle the Mallory Inductance tuner.

case closed

[Larrchild]

You kids have no respect for when Grandpa had to shim the deck-plate.
*shakes cane*.