Tascam 122 MK III. repro reference level setting

[Laszlo]

Hello All,

anyone recently set repro levels on a Tascam 122 MK III? I found that in the service manual, 250nW/m is mentioned for reference level, where as in the playback section of the setting instructions in the same manual they mention test cassette TCC 150, which has 200nW/m for zero dB VU. Any suggestions, which level to use? Shall I set the machine for 250nW/m by calculating in the 2dB difference? I have a test tape with 200nW/m level records.

 

[SkywaveTDR]

No I would stick with the 200 nWb/M flux Dolby MTT150A as this would be as the deck is designed. The 122 Mk III has enough shortcuts in it the way it is without increasing the levels. I don't think you will be able to get good distortion specs increasing the reference 2 dB. Why are all these people always wanting to make a deck better by upping one spec with a blindness for all the others. Don't you think the engineers at Tascam would have increased things on their own if it was possible. Remember what speed this deck moves tape at and then what kinds of heads it has- they are not from Nakamichi.
In order to make any mods to such a deck I would be consulting Alex Nikitin on the subject and he has already upgraded this kind of machine but also increased the speed. He is a person to listen to with regard to mods- I do some of his mods myself.

 

[Laszlo]

Thanks for the response. I did not intend to do any mods, I respect the manufacturers prescriptions of course. My question was based solely on the two confusing data on reference level. The spec part of the manual says 250nWb/m where as the respective test tape MTT150A is at 200 nWb/m. The mentioned 2 dB is the difference between the two levels..

 

[-mjk-]

My question was based solely on the two confusing data on reference level.

Not to mention that 250 nWb/M is studio standard.

 

[SkywaveTDR]

I don't know where this studio standard stuff comes from as most decks I have seen in the past 45 years all were Teac tape referenced or the Sony decks were lower at 160nWb/m. The Dolby tape is a +3 Vu tape and a 0 dB meter tape which is how we set them at Teac.
The Mute diode mod and 4066 IC change out is not that hard to do and in fact I am working on one now. The only deck I heard was a 250nWb/m was a Studer B215 but that may be because it uses DIN levels.

 

[-mjk-]

It comes from professional studios, such as those licensed as TEF rooms. Every studio I worked in circa 80s to 90s were all 250.

 

[Laszlo]

Here we go..

 

[Laszlo]

It doesnt really matter if the test tape has a 200nWb/m or 165 nWb/m reference level, it still can be used to set any other level by calculating the difference. I just did not want to believe that a Tascam cassette deck reference level is at 250nWb/m whereas the same SM instructs to use a test tape with 200mWb/m. But the more I read about it the more I understand. The 122 MK III. was a late model when the studio cassette tapes were advanced enough to use the 250mWb/m reference level. Is it the case?

 

[Evgeny]

I just did not want to believe that a Tascam cassette deck reference level is at 250nWb/m whereas the same SM instructs to use a test tape with 200mWb/m.

It is common practice when reference level with Dolby is a bit lower then without it. Such is not only in casset recorders! So I should rather use a test tape MTT150A (200 nWb/m), adjust by R122/R222 levels at TP5/TP6 (388mV) and then set volumeters by R104/R204 to -2dB. This procedure distinguishes from Service Manual because my opinion is to meter the reference level in repro-channel by reference tape. As for output levels on RCA or XLR, this is a matter of taste.

 

[Laszlo]

Hey Evgeny,
Thanks for your note. I just did exactly this. Thanks for the confirmation.
Cheers,
L

 

[Laszlo]

The only deck I heard was a 250nWb/m was a Studer B215 but that may be because it uses DIN levels.

Well, than check this out, that is probably the right answer..
http://www.gennlab.com/level_cass.html

 

[SkywaveTDR]

I am aware of Gennlab but I use actual MTT and MXT tapes that I got from Teac when I was there or bought after. These were not DIN as I am not in Europe.

The test point wants a -6dBu signal at test points so using test tapes that are not as specified upsets the process and requires add or subtract dB numbers that complicates a procedure. I prefer to just use the tapes that are listed in the manual as I have done since 1982.

 

[Evgeny]

The test point wants a -6dBu signal at test points

Really Dolby-level needs only for Dolby! And even in this case it is not necessary set VU-meters to 0 dB, because Dolby-level may be assigned at all to another value. Dolby-level and refference level are not synonyms!

so using test tapes that are not as specified upsets the process

I'd say not "upsets" but "modifies" or "updates". To update the process if it contains some mistakes or inaccuracies is very good .

and requires add or subtract dB numbers that complicates a procedure.

This is quite not a problem for engineer! I think, any engineer (i.e. a person with diploma of higher education) can, may and have to add +1 or -2 if necessary.