DIY Alignment and Calibration

**ofajen** · 07-31-2009

I've had a Fluke DMM for a while now and it's OK, but I also have an HP analog AC voltmeter and I find the needle on a scale to be much quicker and more intuitive than red LED digits. YMMV.

Cheers,

Otto

**fstrat76** · 07-31-2009

Originally Posted by sweetbeats

There are other ways to do the azimuth...I've used a freeware PC-based oscilloscope plugin that gets it good enough.

I may also be interested in the DIY maintenance.

What freeware did you use?

Also, what's a reliable source for finding an alignment tape for my 38, through Tascam directly?

**miroslav** · 07-31-2009

Here is a great PC-based oscilloscope/analyzer application...freeware.

Visual Analyzer

http://www.sillanumsoft.org/

I use it for setting up my decks…works great.

One thing though about the azimuth...
I've heard a some folks say that unless the heads are virtually brand new and/or have relief grooves cut...then don't mess with any physical head alignments, since the tape has already begun to cut a microscopic groove into the head based on its path (even if it’s not visible)...and once you start physically aligning a grooved head then you stand the risk of messing with your tape path because the tape could end up riding slightly out of the already formed groove (or the beginnings of a groove) and then all the other calibrations will be that much more difficult.

I just picked up a new ¼” half track, an Otari MX5050BIII-2, so I did a full check and physical alignment of the heads, and from this point on I will just be doing electronics alignments until it's time for new heads or a head relap.

Again...this is just what I've heard from a few guys in the past...but when you think about it, it does make sense NOT to mess with a head that's already "settled in".

I would love to hear some more opinions on this...

**fstrat76** · 07-31-2009

Is there another way to test head alignment without the test tape right now, just to see if I even need an alignment?

I think I saw in the 38 manual that its fine if you just continue use the sync head for record and playback, all tapes are only playable on that machine using sync.

My understanding from the manual is that misaligned heads will cause a drop in dB (on the repro head). Of course, my understanding is limited. My original thought was to use a daw to check for phase cancellation of a tone played back on the sync head vs the repro head.

Just a (cheap) thought.

Any other ways?

**A Reel Person** · 07-31-2009

Originally Posted by sweetbeats

Geoff, what's your source for cassette test tapes?
.

Almedio in Japan bought out all the TEAC Test Media business. It's a little tougher to match their catalog numbers to what you actually need, so some 1:1 correspondence to them for clarification might be necessary. It wouldn't hurt to start by referencing the old TEAC alignment tape part number, and work from there.

I bought a TEAC alignment tape or 2 before TEAC sold it off. I have the calibration tape for a 2x speed Portastudio and a 1x speed Portastudio,... by actual part number. I also councilled a little with a TEAC rep on the various part numbers of cal tapes, and was told that several of the different part numbers would be nearly compatible, so you might only need one, then use it on the similar decks. Say, if the 246 manual calls out a specific TEAC test tape , but the 688 calls out a different number,... logic tells you that each one should be similar enough to the other to just buy one to use on both.

It was expensive, though. On the same price level as a reel MRL test tape, or thereabouts./DA

**miroslav** · 07-31-2009

Originally Posted by fstrat76

Is there another way to test head alignment without the test tape right now, just to see if I even need an alignment?

I think I saw in the 38 manual that its fine if you just continue use the sync head for record and playback, all tapes are only playable on that machine using sync.

My understanding from the manual is that misaligned heads will cause a drop in dB (on the repro head).

Record a test tone, and then compare the levels going in VS the playback levels. That's a simple/basic check, but it only reveals one aspect of electronic alignment...there are other steps that a calibration tape will be needed for.

Using the Rec head for playback will not give you as good quality as the standalone PB head...the Rec/sync is mainly a cue/reference signal for your tracking.

**ofajen** · 07-31-2009

Originally Posted by miroslav

One thing though about the azimuth...
I've heard a some folks say that unless the heads are virtually brand new and/or have relief grooves cut...then don't mess with any physical head alignments, since the tape has already begun to cut a microscopic groove into the head based on its path (even if it’s not visible)...and once you start physically aligning a grooved head then you stand the risk of messing with your tape path because the tape could end up riding slightly out of the already formed groove (or the beginnings of a groove) and then all the other calibrations will be that much more difficult.

Well, John Stephens carried this idea to it's logical conclusion on at least some of his machines... the heads were carefully aligned and then glued in place. No physical adjustments were needed or really even possible unless you were doing major work on the heads.

I've made occasional adjustments to azimuth (at least to check, especially when a machine gets moved or heads are relapped and then optically aligned first.) I haven't noticed those adjustments causing problems in doing the electronic alignment.

OTOH, probably there is little risk in leaving the heads in place if the machine isn't moved and the heads aren't pulled or relapped, etc. The exception would be if the head mounts and adjusters aren't as secure as they should be.

Cheers,

Otto

**Beck** · 07-31-2009

Good stuff so far.

Welcome to miroslav!

You definitely need a calibration tape from MRL or TEAC. Unfortunately that is one costly thing you can’t do without.

I listed a few things in the threads below some time ago

Doing a full alignment ...

Calibration Tools

Radio Shack keeps moving their links around (How do they stay in business ?)
http://www.radioshack.com/search/ind...tId=&kw=22-811

And here is another O-scope
http://www.dsp4swls.de/download/oszilight.zip

Can't find Winscope anymore. The people at archive.org should be shot for making robots retroactive. IMO, they either have it archived or they do not. Once they have it (which they did in this case) they should keep it. To freeze time... that's what they're for. It's down right un-American!

/Rant (sorry)

I've only used PC-based O-Scopes for a few years now. They do the trick for tape deck alignment.

One thing to add about using sync or repro heads. It depends on the design of the machine. As a rule the repro head is better, but Tascam broke that rule with a few of their decks. Machines like the 38 and 48, use the same part number for both sync and playback heads. So, you don’t get the same advantage by using the repro for playback as you would with a machine that has a specially designed Repro head.

In a private studio environment your calibration will hold for a long time. When getting a new/old machine I recommend doing a full align (usually needed, but not always). After that you will just check it maybe every six months to see that it is still right on. I go for three years never having to tweak anything.

Yeah, about azimuth... I just go by the scope. If it stays within spec you don't have to mess with it all the time. The surface of the head will change with wear, so it may need a bump now and then over the long term.

~Tim

**miroslav** · 07-31-2009

Thanks Beck!

I have that Radio Shack digital multi-meter (or one very similar to it)...it also has the option to read signals as dBm, so it saves some time.

Originally Posted by ofajen

Well, John Stephens carried this idea to it's logical conclusion on at least some of his machines... the heads were carefully aligned and then glued in place.

While I didn't actually glue the heads, I did drop some nail polish on each of the adjustment screws...though like something someone else once said...they've never seen a screw turn itself, even during transport!

But I guess a good bump or two could make 'em twitch a little.

I only put the nail polish on the screw heads 'cuz I can be somewhat anal about stuff like that!

But I'm the only one touching my studio gear for the most part, and I'm pretty gentle, so I don't expect the screws/heads to ever move physically once they are set.

I'll be doing my 16-track soon, which has seen some use, but even that deck is pristine, and will probably only need a touch-up on the electronics.