Test tones on ALL tape releases??

[stellavox]

Doc,

I may have missed this topic and you may already have it covered - if so I apologize.  I feel it is imperative for you to put (mono, 1Khz?) channel balance and say 3 test tones (100hz, 1K and 10K) at the beginning of EVERY tape, so the customer can check the channel balance and (rough) EQ of their machine.  On second thought, put it at the end of the tape.

Charles

[High and Outside]

This is a good point. Maybe even more than you, we are very interested in seeing all our customers get the most out of these tapes. And we agree that the machine must be set up properly if that's going to happen.

We have been discussing various ways to ensure that. It may or may not involve a set of tones on each album. After I have just had those waves of glorious sound washing over me, about the last wakeup call I want is a 1K tone at zero level coming out of my speakers.

But it will happen in some form. Right now we are leaning toward supplying each charter subscriber with an MRL test tape, and hooking him/her up with a qualified studio tech in his/her area to confirm the machine's performance in situ. Once that's done, I don't think the machines should drift. Regular cleaning and maybe a annual checkup should take care of it.

Paul Stubblebine

[stellavox]

Paul,

I believe that a separate MRL tape is an unnecessary expense - Plus there are unnecessary tones on the tape.  If the playback deck is of any kind of good quality, knowing/being able to adjust the machine at 100hz, 1Khz and 10 khz are within say +- 1dB is all you need to be able to do - the "flatness" over the rest of the band is up to the head/electronics.   3 tones of 20 seconds each - plus the 1khz allows you to set channel balance is all you need - total of 1 minute.  Splice them at the beginning of the first tape and put 6 ft. of leader between so that a user can "fast forward" past them if he/she doesn't want to bother. 

Here's a question - do your masters you plan on using have these test tones?  A number of the masters I have do.  If your's don't, how do you know if the machine they were recorded on was in fact in calibration that day?  Once the tones are on the tape with the original material they are ALWAYS there "thru thick and thin" - even if the subsequent playback/recording (dubbing) chain is in fact slightly?? out of EQ.   

I do agree that once a quality machine is set up correctly, it will stay there - for a LONG time - if not bounced around.  This is where tape has it ALL OVER the finicky LP. 

Charles

[ironbut]

I think I have to side with Paul on this one. For one thing, I like having my own test tape so when I get my machine serviced I can have them use it and I know that it hasn't been abused. Also, I hate being knocked in the head by the test tones on my Barclay-Crockers. And I'm sitting within arms reach the deck but sometimes I forget. But,.. I can see an advantage on having the test tones "on" the actual tape for really fine tuning. As far as the technical issues, I'll just read what you guys think.

[High and Outside]

Here's a question - do your masters you plan on using have these test tones?  A number of the masters I have do.  If your's don't, how do you know if the machine they were recorded on was in fact in calibration that day?  Once the tones are on the tape with the original material they are ALWAYS there "thru thick and thin" - even if the subsequent playback/recording (dubbing) chain is in fact slightly?? out of EQ.   

Charles,

The tapes that we use as a starting point are the original session tapes. Generally they have tones included. I believe that it's a good policy to record project tones at the start of any recording or mix project...that's the way I was trained and that's the way I've been doing it for over thirty years. And yes, I agree with you that these tones should always stay with the tapes. This may not be obvious to some readers, but for me it's second nature now. When I start a recording project on tape, I align the machine using a standard test tape (I have many from MRL, STL and even Ampex). Then once the record side is aligned, I print a set of tones that stay with the tapes. I started doing this way back in my first studio, but I really had it drilled into me during the years I worked for Columbia Records. Some years back SPARS, the Society of Professional Audio Recording Services, standardised the tones to be used: 1K, 10K, 15K, 100, and 50 Hz. This is fine with me, and that's what I generally use. The two HF tones give you both a reference for frequency response and a pair of tones for azimuth that are not harmonically related (long story for another day). The two low frequency tones give you a fighting chance of understanding what's going on with  the head bumps.

Anyway, this is about the original tapes. I'm feeling  the pull to start telling some of the many tales about what we have actually found on tapes coming in...but that's a whole 'nuther thread. When I get a chance I'll start a "War Stories" thread in the Tape Tech part of this forum.

[stellavox]

Paul,

Star Wars experiences PLEASE - as you feel the urge.  Otherwise, thanks for the fascinating background!

Charles 

[ironbut]

I second that! I love war stories about this kinda stuff!

[James Guillebeau]

If you put test tones on the tape then 100 hz is too high to adjust or optimize head bump. And at 15ips you really have to optimize this unless the heads have very wide pole pieces. So IMHO there should be several bass frequencies and fewer mid band frequencies. Just my two cents! Good luck! Docfeelgood

[beefman]

I'd always thought head-bump was more of an issue of the EQ curve and speed than anything else... most enlightening.

[James Guillebeau]

No, head bump is due to the width of the pole piece of the head. Heads for show speeds i.e 3 3/4 are very narrow and as the speed increases the pole pieces have to be made progressively wider due to wavelength. That is if you want good realistic bass at the higher speeds like 15 and 30 ips. At 7.5 ips, you get great bass but as you speed up the tape then the head bump gets larger or so it was told to me. Ray

[stellavox]

Test tones? Separate calibration tape?

What about absolute plase? - checked it on ALL your duplication machines?

THANKS

Charles

[docb]

I can verify that Paul checked absolute phase of both machines today when we made 1" running masters for Jacqui Naylor's The Number White

Paul uses a DK Audio MSD200 master stereo display when he masters. The MSD200 has a vectorscope and phase correlation display to work from, and of course we listened before rolling the tape as well. We will be checking phase on all machines tomorrow when we begin testing the duping line - and checking a whole lot of other things too.

[docb]

As the duping line has been getting fine tuned Paul has come to the conclusion that the very best way to help everyone get their machines dialed in for Tape Project tapes is to offer a copy of our own Tape Project  test tape, that has been made on our duplicating slaves. This avoids having to put tones on every album, and still gives everyone the ability to match the alignment of their playback machine with the original recorder used for the tapes. It also allows us to put some useful tones on the tape that might not be found on other test tapes, and could allow for longer tones than we could put on the albums themselves. Paul can go into a little more detail about what will be on the tape and the considerations behind the choices.

[High and Outside]

I'd like to explain just one of the reasons we decided to take this route--providing test tone reels of our own making. It has to do with the fact that the standard test tapes from MRL or any other source are problematic for aligning the low frequencies.

Some of you guys already understand this stuff, so please forgive my getting basic for the rest of the folks.

Test tapes are recorded full track...the full width of the tape as a mono signal. This makes them usable for several different formats on the same width of tape. In other words, a quarter inch test tape can be used to check a mono machine, a two-track machine, a quarter-track machine, even a quarter-inch eight track. It also means that the signal is consistent across the whole width of the tape, so you're aligning all tracks to essentially the same standard, which is a real advantage.

But it leads to a problem too. When a wider recorded track is reproduced on a narrower playback track (such as a full track test tape played on one of our two-track machines) the head responds to the low frequencies that are outside the official track area, and the result is a reading that's slightly high. But when you're playing back a recording made on a head with the same track width as your playback head, you get the accurate reading. The test tapes come with instructions that basically tell you not to rely on them at low frequencies.

As an aside, test tapes recorded in something other than full track are rare, but not unheard of. Standard Tape Laboratory used to offer two-track versions of some of their test tapes as an option. They were actually recorded full track, then the guard bands were erased afterwards. I have several, and they come in very handy in my line of work. Sometimes I have to deal with tapes that come in without proper alignment tones (I feel another installment of Tales From The Trenches coming on) and it's good to be able to start from a known condition, including the low end.

Anyway, back to our tone reels. We felt it would be a huge advantage to offer our customers a way to align to the same curve that our tapes are recorded on, including accurate alignment of the low end. Providing tone reels made on our own machines allows us to do that.

[docb]

I'll just throw in here that today I aligned one of the RS1500s that is going to NY with a tone tape Paul made for me and it was quick and easy - nice tight x-y slopes on the scope.