Hey Guys, I have a Tascam 48 that I just modified. The Record Amp cards have all new electrolytics for the power supply rails and Nichicon Muse ES between signal stages. LME49720 and LME49860s have replaced all the op amps except for the VU meter amps. .1uF decoupling caps have been added from pins 4 and 8 to ground off each of the new op amps. All is fine, but I'm having some trouble with noise and drop-outs when recording test tones to my re-calibrated unit. I'm using Quantegy 499, but this problem has exhibited itself on other tapes as well. I believe the issue is not a result of the mods I've made (happening pre-mods as well) but instead the tape path or even heads. The heads have a little wear, but nothing completely terrible. Sending signal to the machine, I've monitored via "Input", "Sync" and "Repro heads. The Input, gives me no issues... sounds perfect. I only hear the issue after listening through Repro or listening back through the Sync (record) head. If I press the "Edit button" and scrub through, I can hear the pops, clicks and rumble that were recorded, but only when scrubbing which makes me think the amp cards are just fine and the issue is, again, the heads or tape path... Take a listen and let me know if any of y'all have any ideas. OR is this something I must live with. Tones were 40Hz, 1kHz and 10kHz https://www.sendspace.com/file/cs7ilf
Tascam 48 Noise (with sound file)
- Thread starter ecs787s
- Start date
The Ghost of FM
Banned
Sounds more like smaller spot tape drop outs.
Have you tried recording the same tones over the same piece of tape to see if they occur at the same spots? If they do repeat at the same places, I'd suspect the tape more so then any issue with the tape path unless you're getting rhythmic pops that correspond to the circumference of a roller pit or bump, which I didn't detect when I listened to the file.
Cheers!
Have you tried recording the same tones over the same piece of tape to see if they occur at the same spots? If they do repeat at the same places, I'd suspect the tape more so then any issue with the tape path unless you're getting rhythmic pops that correspond to the circumference of a roller pit or bump, which I didn't detect when I listened to the file.
Cheers!
Man, I thought your suggestion might've been off as I'd already tried a few different tapes. One, which is the aforementioned 499 and pretty new, but just for a sanity check, I opened a brand spankin' new reel of 499 and popped it on there... Low and behold. Noise and artifacts/dropouts are gone! So thank you! BUT, does this mean that the first roll of 499 is just crap? Frustrations!!
The Ghost of FM
Banned
Not necessarily completely useless as the drop outs are pretty brief and might only be at the head of the reel and cleaner more in the middle if it was packed/spooled nicely. I used to always start a recording project a full minute or two into a reel just to be on the safe(r) side.
Cheers!
Thanks for the help! My 48 is up and running very well now... Now one more question... If I fast forward or fast spool and press stop, the brakes don't engage till the reels have slow down on their own and it takes much time for the unit to stop. This is most frustrating when I'm using the Return to Zero feature as it always misses its mark and passes the time by and has to go the other way...
Is this normal? I've calibrated the brakes and made sure the tension is correct. I'm wondering if the brake solenoid is in fact not supposed to engage until those tension arms are at a certain point. Any ideas?
Is this normal? I've calibrated the brakes and made sure the tension is correct. I'm wondering if the brake solenoid is in fact not supposed to engage until those tension arms are at a certain point. Any ideas?
The Ghost of FM
Banned
The transport employs motor servo control which makes use of altering the motor's speed and direction first before the outboard mechanical brakes kick in. So the behavior you described sound like everything is working as it was designed to do. This is done this way for a number of reasons from safer tape handling, to smpte control and for also saving a lot of wear and tear on the mechanical brakes which only need to work on a gentler load rather then being the only way of stopping the reels which would no doubt lead to broken and stretched tapes and far more frequent brake pad replacements.
About the RTZ overshoot, that too sounds normal for that series of decks and also on the 30 series decks which were even more "sloppy" in performing that task. The ATR-60 series transports were a good deal faster and smarter in that particular department as the servo logic was an evolving technology still in that era.
Hope that helps a little.
Cheers!
About the RTZ overshoot, that too sounds normal for that series of decks and also on the 30 series decks which were even more "sloppy" in performing that task. The ATR-60 series transports were a good deal faster and smarter in that particular department as the servo logic was an evolving technology still in that era.
Hope that helps a little.
Cheers!