Ampex "Grand Master," Scotch "Master", et al

The "premium" carts...Ampex's 389 "Grand Master," Scotch's "Classic"
and "Master", and TDK's "SD" series...are all the best offered in the
8 track format as far as tape went in those days. At $4 a pop, they
were also the most expensive. Worth it? You betcha!

I was given the opportunity to test some of Ampex's 389, and did so
this morning. It blows away every 8 track cart I've tested to date.
Noise better by about 5 dB than anything else, and a top end that was
actually too much without some changes in biasing. Once bias was
increased to flatten out the response, it was obvious that the only
limitation was the deck upon which the tape was used, not the tape
itself. Compare this with "cheapie hecho en Mexico" Certrons, which
couldn't provide much in terms of high end unless you were willing to
settle for nasty distortion. Even with less than optimal bias,
distortion on 389 remained very low, and once corrected, got even
lower. I still suspect that this is really the Ampex 406 250 nWb/m
mastering tape formulation on thin, back lubricated backing. I bet if
I popped the reel out and put it on my Ampex 351, I'd get identical
results. The oxide appears to be the same, both visually and
magnetically.

389's overall performance blew away TDK's AD formulation by a mile
simply by being sensitive...about 5 to 6 dB's worth with optimized
bias. Even without correcting for MOL, 389 was even quieter than the
TDK I'd previously tested, which had been the best so far, but
suffered from low sensitivity. Thus, you get the low noise floor
coupled with very high MOL, high enough to the point where my Sanyosak
couldn't hit the 2% THD mark without the head amps clipping. In other
words, you just hit this tape as hard as you can without your deck
crapping out, and get an excellent recording. Not all is perfect,
however...the trademark problems of flutter in Ampex carts was quite
obvious for the first few passes, until the tape "limbered up." Once
past that point, it was acceptable, turning in a .09% weighted
reading, which is a hair below the published spec for the 8075, but
still barely audible in piano passages to the critical ear.

Since this tape eats up just about anything you can hit it with, its
results with Dolby "B" were the best yet. Once you start fooling
around with Dolby schemes, noise measurement gets to be somewhat of a
trick in itself, since Dolby only works on the top end, leaving the
bottom half of the audible spectrum pretty much the same. However,
the results do show up on the A-weighted noise meter quite well.
Ampex 389 was able to turn in a very enviable -65 dB signal-to-noise
ratio referenced to 1 KHz @ 185 nWb/m when using Dolby. This started
getting into professional RTR territory at slower speeds without noise
reduction, using older tapes with lower fluxivities.

More modern tape, like Ampex 456 and 499, can take ever higher
fluxivities, which simply makes the s/n ratio higher before hitting
the MOL "wall" of distortion. My 351, set up for 456 at 320 nWb/m
running 15 IPS, turns in a 66 dB "A" weighted noise ratio using
Inovonics 375 electronics with a 2% THD MOL...and that's with the
linearizer circuits cut out. Once they're cut in and aligned
properly, it gets into the high 70s. That's getting somewhat close to
published CD-A specs of 90 dB. Of course, once you slow down to 7½
IPS, this doesn't happen, and it surely doesn't happen at all on 8
track...the format's just too slow and skinny. But look at the
numbers...with Dolby, the noise performance of my Sanyosak on
record/playback rivals that of a common studio RTR running at 15 IPS
without noise reduction or linearization. Of course, this isn't the
WHOLE story; 8 track is still severely limited by other operating
parameters when recording real-world program material.

Worth hunting down and getting if your a serious and smart 8 track
recordist with a good deck? I'd say so. I wouldn't waste your time
and money doing so if you've got a cheesy Radio Trash or Panasonic or
a portable, however. One thing I do like about the Sanyosak is its
comparitively quiet electronics...not great, but good enough to let a
tape like 389 do its stuff. This didn't come "free," either, as I had
to do a lot of fiddling with bad grounds on the Sanyosaks to get them
to quiet down. Bad grounds seems to be a Sanyosak hallmark, and
cleaning them up gets rid of hum and motor commutator interference to
where they're lost down in the noise floor. Other decks I've played
with have enough noise in their electronics alone to at least
partially mask the benefits of a good tape like this, so it becomes a
"who cares?" situation. Others just don't have the amplifier "oomph"
to hit the tape hard enough to get these kinds of noise numbers. As
it is, the Sanyosak can only hit a +5 VU before starting to break up
as viewed on a THD meter. At a +7, you can start to see hard clipping
on a scope. Cheesier decks can't even do that well. I remember a
Radio Trash (RS-803? Can't remember...) that would start to break up
right at 0 VU! I'm not sure yet, but I think the Japanese-built
Superscopes had about the best head amps for this performance, which
were sold under the Marantz label. Thus, if you're smart with good
gear, 389 and its high priced competition are worth hunting down. If
you're Noodles, stick to Certron and do your listening with one of
those cheesy "console top" players through "Electrobrand" 6 X 9
speakers.

Thus, there WERE good tapes sold for this format, but they obviously
weren't big sellers compared to the "cheapie" formats. Note how Ampex
381, which sold for a buck a shot, seems to be far more prevalent than
the "20/20" series 388 ($2.25/cart), which is more prevalent than 389
"Grand Master" at nearly $4 a cart. Remember, these are 1976 dollars!
People didn't invest much in better tape OR equipment for 8 track; it
was just a noisemaker for cars and portables. However, if you do have
the equipment and the tape, you can get pretty good results, as 389
showed me today. How this'll sound in the car will be seen later
today.

Next: The two Scotches and TDK SD. The top-of-the-line TDK already
promises to blow its cheaper sibling away, but doesn't look like it
can top Ampex. We'll see....

INTERESTING: Quantegy, who now manufactures and sells the former
Ampex line, still markets 16" pancakes of back lubricated cart tape
under catalog number 675. Which oxide formulation this is isn't
clear, but I think it's similar to what was offered in the "20/20"
line of carts.

dB

DoucheBoB wrote in message . ..
The "premium" carts...Ampex's 389 "Grand Master," Scotch's "Classic"
and "Master", and TDK's "SD" series...are all the best offered in the
8 track format as far as tape went in those days. At $4 a pop, they
were also the most expensive. Worth it? You betcha!

I was given the opportunity to test some of Ampex's 389, and did so
this morning. It blows away every 8 track cart I've tested to date.
Noise better by about 5 dB than anything else, and a top end that was
actually too much without some changes in biasing. Once bias was
increased to flatten out the response, it was obvious that the only
limitation was the deck upon which the tape was used, not the tape
itself. Compare this with "cheapie hecho en Mexico" Certrons, which
couldn't provide much in terms of high end unless you were willing to
settle for nasty distortion. Even with less than optimal bias,
distortion on 389 remained very low, and once corrected, got even
lower. I still suspect that this is really the Ampex 406 250 nWb/m
mastering tape formulation on thin, back lubricated backing. I bet if
I popped the reel out and put it on my Ampex 351, I'd get identical
results. The oxide appears to be the same, both visually and
magnetically.

INTERESTING: Quantegy, who now manufactures and sells the former
Ampex line, still markets 16" pancakes of back lubricated cart tape
under catalog number 675. Which oxide formulation this is isn't
clear, but I think it's similar to what was offered in the "20/20"
line of carts.

dB the doucheBag





I found that the TDK was not so great at for home recording on my Soundesign deck.

On Fri, 19 Nov 2004 11:21:30 -0800, DeserTBoB
wrote:

However, if you do have
the equipment and the tape, you can get pretty good results, as 389
showed me today. How this'll sound in the car will be seen later
today. snip

....and I did, and it sounded great. One thing about grading a tape in
the car: The finer points don't really matter, since the system and
the environment in which its heard aren't that good to being with.
What I noticed most about Grand Master in the car was that it was
really hot stuff. The niceties about its super low noise floor just
aren't that noticeable in the car. The really good high frequency
response IS noticeable, but then again, my 8 track system in the car
is a few notched above most, which are barely some old Craig POS with
a couple of 4" kazoos for speakers.

Conclusion: Cheapie Ampex 381 gives about the same hot playback as
389, but without the audio niceties. If you're serious about
listening to 8 track at home, 389's the way to go. If just for a car
or a portable, stick with hot cheapie tape, like 381. Even Certron's
a cheap option, if it's a really marginal system that can't do much
with high end, anyway...as most can't.

dB