Blue Jinn
Rider of the ARPocalypse
I think the voltmeter needs to read AC RMS also. I bought some Fluke DMM from a local guy, same guy I bought a Wavetek something or other overkill signal generator. Now, if he'd just sell me a 'scope....
briank
analog for the people!
Jinn, I got my Tektronix 2235A scope off fleabay for something like 50 or 70 bucks...
T
thereelman77
New member
That is a very old school oscillator!!!
Well, doing the 'hiss test' on the Teac deck the first four channels are a little louder, than the last four (1-4)(4-8) respectively. Noticeable, but not drastic.
Using the test OSC button on the Otari, the meters are off slightly: right meter registers between -4 & 5db, where as the left registers very close to -4db.
I have ordered the oscillator and will order the 1/2" MRL tape.
Well, doing the 'hiss test' on the Teac deck the first four channels are a little louder, than the last four (1-4)(4-8) respectively. Noticeable, but not drastic.
Using the test OSC button on the Otari, the meters are off slightly: right meter registers between -4 & 5db, where as the left registers very close to -4db.
I have ordered the oscillator and will order the 1/2" MRL tape.
T
Tim Gillett
Banned
OK, if they are noticeably different, that probably indicates a playback cal problem. Or does it?...
Are you sure the play head is nice and clean and the tape is contacting it intimately across the full width of the tape?
This is important because the MRL tape doesnt fix this. It just quantifies the extent of the deviations.
Many times I have had reel to reel machines which played back badly because the repro head was dirty, misaligned, magnetised, needing a relap, just plain worn out etc. All the MRL tape does is put this bad performance into numbers, as opposed to sounds that you can hear.
Often there was no need to play the cal tape as I already knew the playback was out by listening. Fixing the tape and head problems are where it's at. The MRL, and any fine adjustments needed, are the final step when all the other work has been done.
Another "short cut" is to open the machine and look at the repro level and eq trimmers. They should pretty much match each other in their positions. If they are moderately or wildly in different positions, there is probably something wrong.
I had an Otari 1/2" 8 track machine in a while ago and my first test was the tape noise on playback listening test which I described earlier. Just listening, some of the 8 tracks were wildly out. I checked the play trim pots (which on this model are on the back of the machine and so easy to view) and some were visibly all over the place, corresponding perfectly with the tracks which were too loud or soft.
No skilled person would ever have set those pots like this. This was somebody twiddling who didnt have a clue what they were doing. They'd made the machine perform much worse, not better.
Just returning these pots by eye to match the others improved the repro cal by a mile. And I hadnt even touched a cal tape.
Also, cal tapes are precision tools and easily damaged so they no longer read accurately. If you do get one, look after it. Make sure the machine you play it on is already in top mechanical condition and the tape path is not magnetised. I would buy a good demagger before a cal tape.
A good protocol with cal tapes (and all tapes actually) is to play wind them and leave them stored on that take up reel. Do not fast wind them off.
Just beware, and use your common sense.
Cheers Tim
Are you sure the play head is nice and clean and the tape is contacting it intimately across the full width of the tape?
This is important because the MRL tape doesnt fix this. It just quantifies the extent of the deviations.
Many times I have had reel to reel machines which played back badly because the repro head was dirty, misaligned, magnetised, needing a relap, just plain worn out etc. All the MRL tape does is put this bad performance into numbers, as opposed to sounds that you can hear.
Often there was no need to play the cal tape as I already knew the playback was out by listening. Fixing the tape and head problems are where it's at. The MRL, and any fine adjustments needed, are the final step when all the other work has been done.
Another "short cut" is to open the machine and look at the repro level and eq trimmers. They should pretty much match each other in their positions. If they are moderately or wildly in different positions, there is probably something wrong.
I had an Otari 1/2" 8 track machine in a while ago and my first test was the tape noise on playback listening test which I described earlier. Just listening, some of the 8 tracks were wildly out. I checked the play trim pots (which on this model are on the back of the machine and so easy to view) and some were visibly all over the place, corresponding perfectly with the tracks which were too loud or soft.
No skilled person would ever have set those pots like this. This was somebody twiddling who didnt have a clue what they were doing. They'd made the machine perform much worse, not better.
Just returning these pots by eye to match the others improved the repro cal by a mile. And I hadnt even touched a cal tape.
Also, cal tapes are precision tools and easily damaged so they no longer read accurately. If you do get one, look after it. Make sure the machine you play it on is already in top mechanical condition and the tape path is not magnetised. I would buy a good demagger before a cal tape.
A good protocol with cal tapes (and all tapes actually) is to play wind them and leave them stored on that take up reel. Do not fast wind them off.
Just beware, and use your common sense.
Cheers Tim
S
sam humans
New member
FYI - you can download tones from Analog Rules!!! Pro-Audio Parts and Service then burn a CD or dump to your Ipod or phone or whatever. Hell, put 'em on cassette if you want! (Analog Rules is a great sight to check out regardless, chock full of good info...)
briank
analog for the people!
You should be able to both see (on the meters) and hear what the MRL is telling you. But yes, do the basic bonehead stuff like cleaning and demagging the tape path first. If you don't already have one, invest in a Han D Mag. I got mine for $50 shipped from Markertek.
Oy vey...play the cal tape, it's the best tool for judging and aligning the repro electronics. But yeah, don't put the cal tape on if you suspect tension problems and always always make sure the tape path is cleaned and demagged before putting the MRL on, lest you damage the tape!
VERY misleading statement, this just isn't true especially in older machines where electronic components are starting to get out of spec. If the trimmers were all meant to be set the same way, you probably wouldn't need them because you wouldn't be needing to compensate for variances lol. If you think or know that the machine had been "tinkered with" by someone who didn't know what they're doing, then yeah it's possible the trimmers are out of whack, but you won't know until you get an MRL on there, get the repro levels calibrated and then can cal your record electronics to that standard.
Agreed, always do a "library wind" for a good even wind, store your MRL tails out and store it carefully away from magnets, moisture and other tape killers. The MRL I just bought came wound tails out and with a big orange sticker reminding you to store it that way, nice touch.
T
Tim Gillett
Banned
No it's not a misleading statement. I described it as a "short cut". I did not say the trimmers were "all meant to be the same way". But I said the trimmers should "pretty much" match, and for very good reason.
The signal from a multitrack repro head in good condition is nearly always very consistent across channels.
That leaves the repro amp. Silicon transistorised repro amps, also in good condition, should also show very little variation between channels.
I've serviced and aligned a lot of tape machines. After a while you get to know the ballpark settings. If the only way I can get reasonable repro cal on a machine is to have the trimmers significantly different from each other, or at the limits of their travel, I suspect my own work. I go back and check my work. Something is wrong.
I shouldnt be compensating for a dud head or repro amp by changing trimmers wildly. That's slack.
Also, it depends on the design of the trimmers in the circuit. Many machines use say a 20kR trimmer as a simple voltage divider (a pad) so that the range of electrical adjustment is far more than you'd normally ever need. Turn them fully clockwise and the level is way too high. Turn them fully anticlockwise and it cuts the signal off completely. (and who would ever need that?) Just because it's possible to turn the trimmer all the way in either direction doesnt mean it would ever be a practical setting.
Head's heads, heads. They used to call them the heart of a tape machine. Look at them. I mean really closely with a powerful magnifier. Are they clean, in good condition, polished like a mirror? Are they physically aligned. Are they demagnetised? Does the tape contact the gaps perfectly?
Is it really the play cal that is off or is it the record head is worn and/or is overbiased? Are there other faults such as with heads and amps?
A good tech knows if the play cal is within ballpark without even pulling his cal tape out of the box. A bad tech just slaps on the MRL -which he's probably already ruined by careless use of it - and thinks the technology will compensate for his ignorance. Usually it doesnt.
Sorry to "pull rank" on you but I've done a lot of this shit.
Tim
B
Beck
Guest
Oy vey is right!
Thanks briank. I tried to leave you some good feedback for helping keep things real, but it said I had to spread it around.
And apologies to thereelman77 on behalf of homerecording and Audiofanzine that the thread has gotten off track due to some personality clashes... to put it nicely. I don't officially represent HR and thus the apology is not officially official but I've been around long enough to feel someone has to do it.
What a mess of something so simple and standardized in recording that it's basically incontrovertible. How one member, with no rank to pull, by the way can totally screw up the most basic process is just amazing... but it happens on every forum. HR is one of the best. I wouldn't stick around if I didn't see the value and even greater potential the analog forum has.
Well, if we can't laugh about it there's nothing else we can do about it. I feel like Hawkeye on M*A*S*H trying to deal with Frank Burns when things get this silly. I learned a lot from that show... how to keep ones sanity while surrounded by insanity.
Edit: I’ve decided to edit this reply in the spirit forum harmony and Sticktothesubjectuity (not an actual word).
Last edited:
briank
analog for the people!
Thanks for the kind words! thereelman77, let us know when your MRL comes in and we'll go from there!
T
thereelman77
New member
Beck, thank you for the apology, but I do understand the tendency to "troll" as they say. I feel that Mr. Tim was trying to express more of his opinions based upon his own experiences.....But thank you either way...
I haven't really had any issues as far as recording and playback level issues, which I assume would suggest mis-aligned tape heads. I have been tracking for 4 months (not consistently, but randomly) and haven't had (as far as I can hear) any problems with the recording/playback/tracking volume. I'm just relieved that my session that was supposed to happen this weekend got bumped 2 weeks, so I won't need to calibrate it in 2 days.
- I was reading the above posts sporadically, but I do have a de-mag device, I'm going to use that analog rules link to save myself some $$ buying the oscillator, unless I should get the physical one?
- I learned to do "library winds" after my first tape; all of my tapes are stored on the take up reels. I thought my FW & RW was messed up, but picked up on that one pretty quickly.
- Tape tension is fine, I always clean heads before and after every use, I haven't de-magged since the day I got it, but I haven't used the deck for more than 100 hrs. I Know it needs one.
- I clean all tension arms as well as rollers after every use. I was wondering if you guys could actually recommend proper tape cleaning utensils for the cleaner solution, I use basic Q-tips.
- I will be gone for the next 4 days, but will try and order the tape over the weekend, the 1/2" MRL.
briank - Yes, when it comes in, we will move on from their.
I haven't really had any issues as far as recording and playback level issues, which I assume would suggest mis-aligned tape heads. I have been tracking for 4 months (not consistently, but randomly) and haven't had (as far as I can hear) any problems with the recording/playback/tracking volume. I'm just relieved that my session that was supposed to happen this weekend got bumped 2 weeks, so I won't need to calibrate it in 2 days.
- I was reading the above posts sporadically, but I do have a de-mag device, I'm going to use that analog rules link to save myself some $$ buying the oscillator, unless I should get the physical one?
- I learned to do "library winds" after my first tape; all of my tapes are stored on the take up reels. I thought my FW & RW was messed up, but picked up on that one pretty quickly.
- Tape tension is fine, I always clean heads before and after every use, I haven't de-magged since the day I got it, but I haven't used the deck for more than 100 hrs. I Know it needs one.
- I clean all tension arms as well as rollers after every use. I was wondering if you guys could actually recommend proper tape cleaning utensils for the cleaner solution, I use basic Q-tips.
- I will be gone for the next 4 days, but will try and order the tape over the weekend, the 1/2" MRL.
briank - Yes, when it comes in, we will move on from their.
briank
analog for the people!
I use industrial wood stick swabs from my local electronics shop, I get them cheap and am pretty sure I'm the only one who buys them lol. But paper stick qtips are ok too. I also use cotton balls for the rollers.
I use 99% isopropyl alcohol for the heads, guides and rollers. I have had trouble finding it at pharmacies but I get the 99% iso at my local Fleet Farm store (I'm in Wisconsin, not sure if there's anything like that in your area). I have some re-grip that I use only once in a blue moon for the pinch roller. I recall somewhere in one of the MCI tape machine manuals that they suggest Formula 409 by name for the pinch rollers for general cleaning. I also use a little of the isopropyl for my capstans in they need it. For the most part the pinch roller and capstan stay pretty clean unless I'm using a dirty tape like ATR.
I Han-D-Mag the heads about every 10 hours or so, which is every session or two.
I use 99% isopropyl alcohol for the heads, guides and rollers. I have had trouble finding it at pharmacies but I get the 99% iso at my local Fleet Farm store (I'm in Wisconsin, not sure if there's anything like that in your area). I have some re-grip that I use only once in a blue moon for the pinch roller. I recall somewhere in one of the MCI tape machine manuals that they suggest Formula 409 by name for the pinch rollers for general cleaning. I also use a little of the isopropyl for my capstans in they need it. For the most part the pinch roller and capstan stay pretty clean unless I'm using a dirty tape like ATR.
I Han-D-Mag the heads about every 10 hours or so, which is every session or two.
Last edited:
miroslav
Cosmic Cowboy
I think it was Beck who turned me on to using cotton facial pads...the ones that women use to remove their makeup.
They are not practical (IMHO) for smaller format machines, as trying to clean the heads/guides on a 1/4" or 1/2" deck is (IMHO) much easier with Q-Tips (I use the paper stem ones)...but for my 2" machine, the facial pads are absolutely THE way to go! I was going through a handful of Q-Tips to clean the 2"...but with the facial pads, I can use a single pad, and by simply using both sides and both ends, I get the heads and tape path clean. I'm sure they would also be great for 1" decks.
thereelman77
Yes, you can get a lot of info from visual inspection of a deck and from basic rec/playback listening tests and VU meters, and just to "use" the deck, you may not want or care about maintenance perfection...
...but don't kid yourself, doing a complete by-the-book alignment and calibration will always reveal so much more, and you will be surprised how much even small adjustments can make a difference, but you will never be able to do that "by eye" or by using some assumed "default" settings of pots and switches.
Don't worry about your pots ending up in different positions from channel to channel, as long as the channels end up equally calibrated in the end. That's why the pots are made to be variable.
The only time you can have a problem is when a pot reaches it's min/max limit, and you are still not at proper calibration...which would suggest that some components are showing age beyond their design limits.
Anyway...it looks like you are already on the right path...so I'm just reinforcing your decisions.
They are not practical (IMHO) for smaller format machines, as trying to clean the heads/guides on a 1/4" or 1/2" deck is (IMHO) much easier with Q-Tips (I use the paper stem ones)...but for my 2" machine, the facial pads are absolutely THE way to go! I was going through a handful of Q-Tips to clean the 2"...but with the facial pads, I can use a single pad, and by simply using both sides and both ends, I get the heads and tape path clean. I'm sure they would also be great for 1" decks.
thereelman77
Yes, you can get a lot of info from visual inspection of a deck and from basic rec/playback listening tests and VU meters, and just to "use" the deck, you may not want or care about maintenance perfection...
...but don't kid yourself, doing a complete by-the-book alignment and calibration will always reveal so much more, and you will be surprised how much even small adjustments can make a difference, but you will never be able to do that "by eye" or by using some assumed "default" settings of pots and switches.
Don't worry about your pots ending up in different positions from channel to channel, as long as the channels end up equally calibrated in the end. That's why the pots are made to be variable.
The only time you can have a problem is when a pot reaches it's min/max limit, and you are still not at proper calibration...which would suggest that some components are showing age beyond their design limits.
Anyway...it looks like you are already on the right path...so I'm just reinforcing your decisions.
T
Tim Gillett
Banned
miroslav;3935614Anyway...it looks like you are already on the right path...so I'm just reinforcing your decisions.[/QUOTE said:
Last edited:
B
Beck
Guest
Well that’s very nice of you, but stick around for a while and you’ll figure it out. We can’t expect new members to know the long-time problem members, or the experts from the pretenders. Hell, even some of the mods don’t know.
We are pretty fortunate here to have the insightful members we do with various backgrounds and expertise. But it only takes one bad apple in a web forum to bring chaos. I wish everyone out here on the web were sincere and mentally sound, but since that’s not the case one must be careful. People are asking questions of total strangers and in that way web forums are all a bit like navigating a minefield for everyone.But I may address the sociopsychological issues of social networking at another time in a thread dedicated to that, and I think it’s as legitimate issue as any, because a forum can come to a screeching halt when these things get out of control. But I’ll leave it there for now.
Back on topic.
Sounds like you're coming along nicely. I got busy with life things, work and so forth so I didn’t follow up with details as soon as I had planned. Got really busy fixing storm damage for some wireless network clients. As a flatlander being on top of a 200 ft comm tower is the closest I get to a mountaintop view.
The thread has evolved a bit so some of the info I was going to share has already been covered. I’ll share some things I had already started writing before anyway, but omit some of it. I always think of future members who find these threads through google search anyway, so no thread ever really dies.
Firstly I hope I got here in time to make specific calibration tape recommendations because you can save a few bucks if you know what to look for. Below are the choices you have for your Tascam deck. MRL is the only one making them now, but you may come across one of the others on eBay or Craigslist. Hopefully you’ll see this when you get back and before you buy a cal tape.
A note about the calibration tape, which I’ve shared from time to time over the years here is this:
A calibration tape is to recording as a ruler is to carpentry. If you start calibrating without one or try to make your own by recording tones to tape using your machine it is the same as taking a random piece of wood of unknown length and declaring it a yardstick. So a foot on your yardstick may or may not come close to 12 inches. Thus everything you build using your made up yardstick will be off from the rest of the world. Hope that makes sense. This is why we have standards in every area of engineering and design. And the manufacturers design and build tape machines to universally agreed upon standards. They are optimized to those standards. All the specifications, such as signal-to-noise ratio, total harmonic distortion, modulation noise, crosstalk, Print-through, frequency response, etc depend on careful calibration. The MRL tape is the beginning, and then you use the type of blank tape you plan to record with to do the rest of the calibration. You can do mechanical adjustments like tape tension first with the tape you’ll use to record. And demag and clean the heads first. Doing it this way will keep your MRL tape in good condition for many years. But some of the mechanical head alignment like tape wrap (tangency) and azimuth depend on the cal tape for fine tuning.
Some years ago I came into a case of half-inch TEAC calibration tapes from the music department at the University of Illinois. I sold them at rock bottom price… much less than MRL. I wish I still had one for ya, but I only have one left for myself now. I also have the MRL31J229 equivalent tape and they are almost identical.
At first I misread your original post and thought you had two half-inch 8-tracks, one Tascam and one Otari. Now that I got that straight I’ll make some specific recommendations of what cal tapes to look for.
For half-inch 8-track (also applies to half-inch 16-track for other readers that run across this thread)
MRL 31J229
MRL 341-673-482-103
TEAC YTT-1144-2
Fostex 9200
BASF 337534A
Except for the fostex these are 15 ips 250 nWb/meter and IEC1 EQ which is standard for Tascam 8-tracks. The Fostex is 320 nWb/m. You could use it and compensate for the difference, but IMO best to get tools as straightforward as you can when starting out.
The MRL 31J229 is the full cal tape and basically equivalent to TEAC’s YTT-1144 cal tape, but…you really only need the MRL 341-673-482-103, the so-called minimalist tape to do a full calibration. You can save around $75 bucks buying the MRL 341-673-482-103 instead of the 31J229, depending on where you buy it.
I use a small Fostex handheld oscillator, model TT-15. And also an alignment CD with a portable CD player that has RCA outs. I can use either and it's really amazing how perfectly the two agree with levels. The CD and player outputs measure exactly .316 mV for 1kHz -10 dB @ 0 VU. That's what your input/output line levels should be for the Tascam and that's the first electronic alignment step before the cal tape is used. If you have a model with XLR ins and outs that will be +4 dBm of course, not -10.
I use a free soft O-Scope with my PC and it works like a charm... more than adequate for azimuth. I've had it since Windows 98 days and it still works with XP. I have the download link for it around here somewhere. I need to dig it up. And put the link here.
To measure levels and frequency I have a fairly modest Radio Shack digital multimeter, Model 22-811. I used to be into ham radio and used it for that as well. It’s very accurate compared with some of the old expensive boat anchor size test equipment I used to have. I got out of radio because it was just one too many hobbies, but I still have too many hobbies.
miroslav
Cosmic Cowboy
I was replying to the OP...or didn't you notice that I put his name in bold above the section that you quoted...?
If I'm agreeing with Beck, briank and a few other folks here about some tape deck procedures...and you happen to have a different opinion about them....mmmmm, that's not me having "a go" at you, that's just me agreeing with them because that's how I would also do those audio procedures.
When I have something to say to you...I will start it off with your name in the post, otherwise, I'm not replying to you or having a go at you.
A Reel Person
It's Too Funky in Here!!!
Yes,...
I have and use both of those, also!
OMG! That photo is about 4x the actual size!
MRL 31J229
small Fostex handheld oscillator, model TT-15
I have and use both of those, also!
OMG! That photo is about 4x the actual size!
Attachments
T
Tim Gillett
Banned
I was replying to the OP...or didn't you notice that I put his name in bold above the section that you quoted...?
If I'm agreeing with Beck, briank and a few other folks here about some tape deck procedures...and you happen to have a different opinion about them....mmmmm, that's not me having "a go" at you, that's just me agreeing with them because that's how I would also do those audio procedures.
When I have something to say to you...I will start it off with your name in the post, otherwise, I'm not replying to you or having a go at you.
You can say that but why would you say, "but you will never be able to do that "by eye" or by using some assumed "default" settings of pots and switches." if it was not a direct reference to - and a distortion of - what I - and only I - had mentioned to the OP?
It doesnt matter if you mentioned my name or you didnt. You were directly referring to what I said. And you distorted it to score a point. It's on record. Too late to back out now mate.
miroslav
Cosmic Cowboy
There's nothing I'm trying to back out of...mate.
If you want to find something in every post that you feel the need to dissect and reply to as though it's directed at you and only you....I can't stop you from doing that, but that doesn't mean it is directed at you.
Like I said...if I have something to say to you, I will always quote you or state your name at the top of my post.
I was actually referencing briank's post and simply agreeing with him...and mainly speaking to the OP.
If a bunch of folks here agree on some procedure and you disagree with it...that doesn't mean they are agreeing JUST to disagree with you.
They are agreeing because that's the way they like do it and that's what they feel is right, so you might want to stop trying to set everyone straight in the Analog Only forum just because you have different views.
You coming in here and constantly trying to be some sort of "myth busting crusader" is coming off as trolling.
People are reporting some your posts here as trolling....consider that.
T
Tim Gillett
Banned
There's nothing I'm trying to back out of...mate.
If you want to find something in every post that you feel the need to dissect and reply to as though it's directed at you and only you....I can't stop you from doing that, but that doesn't mean it is directed at you.
Like I said...if I have something to say to you, I will always quote you or state your name at the top of my post.
I was actually referencing briank's post and simply agreeing with him...and mainly speaking to the OP.
If a bunch of folks here agree on some procedure and you disagree with it...that doesn't mean they are agreeing JUST to disagree with you.
They are agreeing because that's the way they like do it and that's what they feel is right, so you might want to stop trying to set everyone straight in the Analog Only forum just because you have different views.
You coming in here and constantly trying to be some sort of "myth busting crusader" is coming off as trolling.
People are reporting some your posts here as trolling....consider that.
Funny you should talk about a "myth busting crusader"...
Hello Tim Beck. How's the crusade going up on the Mixing Forum at the moment? A bit of "outreach"? Hoping for a new recruit or two? A new candidate to groom for "your" forum down here?