Tascam m520 & teac 85-16

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happybirthday

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Hey Gang, my first post here.


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Looking for some help understanding my new setup. My problem is fairly simple:

The VU meters on my machine read at about -10 when bumping above 0 on the mixer. I understand both ins and outs on both the tape machine and mixer are -10db. They both have rca connections, and i have simple unbalanced cables between them.

When i play the recordings back, they seem to come out a little bit hotter from the tape machine, however even climbing up to 0 on the machine meters, its maxing out my vu on the mixer. The preamps are at an acceptable level, it seems like the meter bridge is calibrated wrong...

I have made a few recordings and they sound ok, would love to have the meters somewhat matched.

perhaps an adjustment on the machine? anyone have experience with this?

TIA
 
If it's playing back from the tape louder than it went in, that generally means that it's not set up for the type of tape you're using. It would have been factory set for SM911 (Ampex/Quantegy 456), so the playback levels will be off it you use SM900 instead.

However, the mismatch between the mixing desk and the tape deck... I was going to suggest making sure the preamps on the mixer are correctly set for -10 but it sounds like you may have done that. Have you tried setting them for a +4 signal in case the previous owner of the deck set it up that way instead?

The manual will have a section on aligning the tape deck - the first step is usually to calibrate the inputs and make sure they zero at your chosen level, so you should probably consider doing that. You'll need a signal generator of some kind - I use an NTI minirator for this, they're not cheap but they're nice and accurate.
 
Your machine needs to be calibrated - starting with the meters. Use 1k at 0 for that and make certain noise reduction is switched out. Once you've aligned the entire machine things should match. Once dbx is engaged, the meters won't match because they are reflecting what the dbx is doing to the signal.
 
Thanks for the quick replies!

Im using a new reel of SM911, i have the dbx bypassed and will not be using it until some new cards arrive.

I cant unfortunately find a manual for the 85-16 and there is no adjustment section in the M520 manual. I have a tone generator that is built into the board. Ill try adjusting the VU's on the machine today to match 1k at 0 on input.

I dont have an oscilloscope yet, but should have one in the next week or so if a deal goes through.

Ill have to open up the M520 today as well and see if there are adjustments on the pres.
 
How are you sending to the machine and how are you returning it to the mixer?
 
RRuskin said:
How are you sending to the machine and how are you returning it to the mixer?
Click to expand...

Im running signal from the M520s buss master RCA connectors to the 85-16s input section.

On the way out of the 85-16 i send the outputs to the tape ins on channels 1-16 on the M520.



UPDATE: i managed to adjust and sync the meters between the 2 machines. Now i have a uniform 0dB across both machines with 1k test tone. Was very easy, i felt pretty stupid for asking for help, however you gave me the courage and inspiration to try it!

However now i have a problem with low record levels, im having a hard time beacuse the 85-16 manual isnt readily available and the 85-16b has slightly different cards and balanced inputs. So it havent been able to adjust it for the SM911 yet. Working on it right now. Will report later.
 
happybirthday said:
Im running signal from the M520s buss master RCA connectors to the 85-16s input section.

On the way out of the 85-16 i send the outputs to the tape ins on channels 1-16 on the M520.



UPDATE: i managed to adjust and sync the meters between the 2 machines. Now i have a uniform 0dB across both machines with 1k test tone. Was very easy, i felt pretty stupid for asking for help, however you gave me the courage and inspiration to try it!

However now i have a problem with low record levels, im having a hard time beacuse the 85-16 manual isnt readily available and the 85-16b has slightly different cards and balanced inputs. So it havent been able to adjust it for the SM911 yet. Working on it right now. Will report later.
Click to expand...

Do you have a 1" test tape? You now need that to calibrate playback levels. You can't properly do the record side without 1st doing the playback.
 
happybirthday said:
i managed to adjust and sync the meters between the 2 machines. Now i have a uniform 0dB across both machines with 1k test tone. Was very easy, i felt pretty stupid for asking for help, however you gave me the courage and inspiration to try it!

However now i have a problem with low record levels, im having a hard time beacuse the 85-16 manual isnt readily available and the 85-16b has slightly different cards and balanced inputs. So it havent been able to adjust it for the SM911 yet. Working on it right now. Will report later.
Click to expand...

You're just guessing with the meters....which is why your meters are not reflecting the correct levels.

There's an actual process to calibrating tape deck levels...and you need a tone generator that can provide known, calibrated levels and specific frequencies...not to mention, you will also need a proper test tape, and a scope to do the complete calibration.
Until you can do all that per the manual, you're just guessing.

Also...you keep saying the manual isn't readily available....I provided links to it in my previous post above...30 seconds on Google to find them.
 
Use a 1KHz sine wave signal to cause both items to read at 0 Vu and they should match. Sounds like to me someone was in a deck and calibrated it the wrong way- there are a lot of boneheads out there following their own ways other than the service manual. The deck as in all decks should input 1KHz at 0 Vu and then record at the same level when switched to Repro while recording. I have worked with these products at Fireside Recording studio and they all matched up and of course they were done correctly as I worked at the Teac Chicago Factory Service- that was why they hired me to do the work.
 
skywaveTDR said:
Use a 1KHz sine wave signal to cause both items to read at 0 Vu and they should match. Sounds like to me someone was in a deck and calibrated it the wrong way- there are a lot of boneheads out there following their own ways other than the service manual. The deck as in all decks should input 1KHz at 0 Vu and then record at the same level when switched to Repro while recording. I have worked with these products at Fireside Recording studio and they all matched up and of course they were done correctly as I worked at the Teac Chicago Factory Service- that was why they hired me to do the work.
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You are assuming that the meters are calibrated accurately, otherwise you are flying blind.
 
You'll also need a quality AC voltmeter that will accurately read millivolts. I have an HP 400EL.

0VU should be around .316volts AC out from the board and out from the deck.
 
Good evening, i must have not made myself clear enough let me rephrase a few things.

1. My machine is a 85-16 not an 85-16B, it seems impossible to find a manual for the 85-16. The Machines are slightly different, and the adjustment procedures are different. I own a hard copy 85-16B manual but the cards and adjustments are all different. If anyone finds a copy for sale please let me know, tascam hasnt got back to me yet, i think they lost it.

2. The previous owner calibrated the machine for whatever reason and only adjusted the record level and VU meters. I got lucky, i have a FLUKE AC meter that can measure millivolts and im getting a scope very soon.

3. The board which im using TASCAM M520 has a built in tone generator, which i used at 1k 0DB to calibrate my meters and record level. Once again i got lucky as my playback levels matched after adjusting the VU and Record levels. I recorded 1k test tone onto my SM911 tape, and adjusted the rec level while monitoring the playback head.

4. I have an MRL test tape, but its very old and extremely sheddy, im looking to borrow a food dehydrator from my friend to bake it. Stay tuned.

5. The machine is operating well at this point, i will get some more tools and give it a proper once over. Thank you for your input, you will be hearing from me soon!

Best Regards,

Mikhail.
 
I'm pretty sure that the only differences between the 85-16 and the 85-16B are in the transport, not the electronics.
 
the transport looks identical. do you not believe me when i say the schematics/instructions dont match my machine?
 
happybirthday said:
the transport looks identical. do you not believe me when i say the schematics/instructions dont match my machine?
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I believe I know more about that machine than you do. As operator of TASCAM's studio, I burned in the prototype 85-16 and the 1st one to come off the production line. The transport of the production units was changed from the prototype and suffered from minute speed inconsistencies. The the 85-16b corrected this. Electronically it was exactly the same. +4 was in all likelihood an add-on option. Here's a quote from: ?????
The 85-16B is nearly identical to the original with the exception of the color and slightly more flexible internal signal routing. Additionally, the 16B sports a redesigned capstan servo amp which reduces flutter. The original capstan amp had a tendency to overcompensate for slight variations in speed.

I brought this speed problem to the attention of the techs and suits.
 
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Most VOM type meters- most Flukes included- will not respond accurately above 100HZ, and also most will not read true RMS like a analog VTVM. I send a PM about the 85-16 manual. I have a original. The Capstan PLL was a PITA to troubleshoot.
 
wkrbee said:
Most VOM type meters- most Flukes included- will not respond accurately above 100HZ, and also most will not read true RMS like a analog VTVM. I send a PM about the 85-16 manual. I have a original. The Capstan PLL was a PITA to troubleshoot.
Click to expand...

Good point. I also have a Fluke 8050 which will read to 200kHz, but the analog meter is easier on the eye. I should have been more specific.
 
In my work with these machines I have always used a AC Millivolt meter to calibrate the decks and so a DVM is a last resort and they are digital that have readings jumping around a lot- that is why an AC analog meter is better for this. The Leader LMV181A has been a favorite device to use for this kind of measurement.
The test tape can be treated with Nu Finish car polish but a 1" tape might be a lot more trouble than a 1/4" one. If you are successful with the Nu Finish the tape will last a while- baking it will if sticky revert back to that in a few days max. The tape needs to be sealed from moisture which the Nu Finish will do. I have alignment tapes I have used it on. It only fixes stick tapes not other things. Baking is only for sticky tape and not for other things either.
 
thanks for all the helpful comments guys, im acquiring tools for repair and trying to learn as much as possible. best regards.
 
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