Cassette Tape MOL and/or SOL

sweetbeats

sweetbeats

Reel deep thoughts...
Anybody know off the top of his/her head what the MOL or SOL in nWb/m is for cassette tape? Its on the tip of my brain...

I'm wondering because I've been rolling this idea around in my head regarding my Tascam 234 4-track machine. I think it may be more trouble than it is worth, but the answer to the above would put the last nail in the coffin.

The audio power rails are +/-12V in the 234. It looks like most of the components in the audio circuits can handle +/-15V. I think Teac went with +/-12V because that's what the dbx circuitry runs on, and multiple audio rails would considerably complicate things in an already fairly dense chassis.

BUT...

Its rolling around in my head because of the higher headroom the higher power rails would afford, but its not really even worth it if the recording medium can't take advantage of the higher headroom anyway.

Anybody?
 
Also, the 234 is primarily a straight 4 track recorder, so it might be good enough to have your 15 volt rails on your external mixer where the real dynamics can be dealt with and tamed down to feed a nice clean and healthy signal to the 234. Odds are, TEAC took that into account when they designed it.

Make sense?

Cheers! :)
 
It's different on different brands of decks! I have seen 160, 200 and even 250. I have a Teac Dolby alignment tape that's a ~400Hz tone at 200nWb.

I just aligned a Yamaha K-1020 where the service manual said 160. Just scaled the voltage measurements by a factor of 1.25 playing back my Teac tape, it seems to have worked out alright.
 
There is a refference made for the 234 dealing with a +6VU signal which represents 320 nWb/m but that's at 3% THD.

The design objective on the 234 with dbx running is to keep the signal lower and cleaner which will also improve the frequency response from 14Khz @ 0VU up to 16 Khz @ -10VU, which is the level the dbx circuitry is looking for to perform at its best.

Cheers! :)
 
Jeff...lots of good points...you are quite right in your thinking I believe considering the dbx, and after thinking about it more (and doing some rough calculating in my head) with the generally lower MOL of cassette tape I'm thinking the +/-12V rails afford enough headroom that tape saturation is reached before the electronics clip anyway...and with the dbx there's no incentive to run the levels that hot anyway.
 
I'd assume that TASCAM intentionally wanted to scale back the headroom on the mic and line inputs so that it wouldn't conflict with their healthy Portastudio product lines and also promote their smaller mixers to work along with the 234. Those mic inputs were really just there for rudimentary jobs like radio spot production where you'd just need a simple voice over or two over top of a pre-made music bed track or as a teaser feature to help out a cash strapped musician while he's saving up for a proper mixer to go with it.

But your idea to beef that up is not without merit as more headroom is usually not a bad thing to be in possession of. But, I'd also suspect the 234, as wheels go, doesn't really need to be reinvented. :)

Cheers! :)
 
Good point!

I think the 160 nWb/m SOL is to allow "clean" headroom for the needle to travel up to +3VU, and to not produce audible distortion until the needle hits the right side very hard.

I also think the (4) 1/4" mic inputs w/preamps allow for the quick & easy 4-mic remote recording without a mixer. That, and the onboard stereo monitor/mixer goes hand-in-hand & makes the 234 a BEAST of high tech engineering!

:spank::eek:;)
 
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