|
Audio Asylum Thread Printer Get a view of an entire thread on one page |
For Sale Ads |
68.104.11.135
In Reply to: RE: Leader tape? posted by Victor Khomenko on March 16, 2024 at 14:52:23
I will check if the SM for this machine has calibration specs I can handle with just a calibration tape and scope.
I believe MRL recommendens their "multi-frequency" tape for my amateur situation with a non-pro machine.
If it can be done with just a scope, I will spring for a tape from MRL. If it requires more specialized test instruments than just a scope, I will see if I can find someone local here in Sin City to do a calibration after I complete my work on the deck.
I won't ship it. Too many disappointments trying to ship - and receiving
damaged - fragile equipment these days.
Follow Ups:
You should start with reading the service manual for that machine, if available. Then get the tools they mention.
yep, I have been reading and I have an original copy of the SM so the pics are pretty good!
Seems like a head azimuth alignment should be within my capabilities here. BUT that will require a calibration tape.
The idea is to play the calibration tape segment of one frequency (1khz for example) with the two channels of deck output going to a scope.
Channel one vertical and channel two the horizontal.
The idea is to check for correct phase of the two channels. Perfectly in phase scope picture using the above scope connections would show as a single straight, steady, line at 45 degrees, angling towards right side of the display, from bottom to top.
That would only be simple head azimuth alignment. Does not calibrate for recording such as flux strength, distortion, etc.
But I only care about playback anyway so worth a try I guess.
Azimuth should be set using higher frequency, typically it is 16KHz.
But there is a danger with that method, which is locking on the wrong peak. This can easily happen at high frequency because the wavelength is so short.
To avoid it is recommended to start at some lower frequency, such as 400Hz, then move to higher ones.
Another way is to turn the azimuth control for maximum output at 16KHz, and THEN do the phase thing.
You will never get a nice line at that frequency, you are always going to have a narrow breathing ellipse, so just make it as narrow as possible.
Thank you Victor, really appreciate the help!
It may not help the sound quality to do the azimuth, but I figure it can't hurt?
And it is nice to learn about the tape recording. What a huge leap forward it was when it was invented in the late 30's.
And I see there are musicians that still covet the sound qualities of analog tape, to the point where there are numerous expensive digital devices and software in use to try and mimic those qualities.
I have an old TEAC demagnitizer, I will do that today. Deck powered off, unplugged. Power up demagnitizer at least 1 meter from deck, move very slowly to the deck, move demagnitizer very slowly around heads, capstan, tape guides...
What could go wrong :)
"there are musicians that still covet the sound qualities of analog tape"
One reason is that tape saturates 'gently' - it doesn't hard clip. So, a competent (or lucky) recordist can run the level a little hot, thus getting a better s/n ratio overall, without obvious distortion - rather, a little gentle compression, without adding a compressor. (Although, a limiter is sometimes a good idea anyway, like that time when I recorded the Schubert piano Fantasia in F Minor...)
*********
We are inclusive and diverse, but dissent will not be tolerated.
That is the simplest way that gets you into 95%, we used it for ages and it is still works fine today.
You need a known good high quality studio recording for that, any music, but best if it has a lot of high frequencies.
Better be done through the headphones, as otherwise you would have to be in the line of tweeters firing.
Play the tape and set the azimuth for best high frequency reproduction.
hmm, I am almost 72. Probably better off using the scope rather than relying on my hearing...
...at how accurately you can set it, even at that age.
I think I will dub all my tapes to DSD before I try anything to the deck that could screw it up.
Right now, after the deep cleaning and lube it is sounding great. Almost to the point I wonder if I could _only_ make it worse by fumbling with the heads.
What I will do is try some analysis with the scope. See what I can discern in the way of performance. Probably will need to spring for a calibration tape to even do that though...
You are correct... if it is "sounding great" then don't go inside without the proper knowledge and tools, you will, most likely, just make it worse.
One thing I learned about this deck. The main motor - which happens to be the only motor in the deck - is electrically "noisy". At least with the cover off...
My left speaker (as opposed to my left nut ;) is only a few inches away from where I placed the deck, and when the main motor is running (transport paused so the music does not mask the sound) I can hear a "fluttering" noise from the speaker. Low level, and only when the main motor is idling, but when no music playing it can be heard with the ear close to the speaker. The speakers are not magnetically shielded (Reference3A DeCapo I)
Right speaker which is almost 3 meters from the deck has no fluttering sound. I did not go through the trouble of physically switching speakers to confirm it is the deck and not the speaker but it is the deck. The speaker is fine...
Probably I will not attempt to add shielding to either the deck or the speaker...
FAQ |
Post a Message! |
Forgot Password? |
|
||||||||||||||
|
This post is made possible by the generous support of people like you and our sponsors: