biasing a 388 for 0db tape
- Thread starter mr.blisset
- Start date
garww
New member
Doesn't do any good if the heads are mucked, does it ?
So, on initial inspection and testing, one finds the heads are not pristine. One has to decide how much time to waste : ) What level of sophistication might be possible ?
So, you care so little about the alignment of your tape machines that you don't even check the heads before line up? how do you service your car? Lick a finger and stick it in the air? "Yeah! Right, that'll get us 1000miles down the freeway...
Dave.
sweetbeats
Reel deep thoughts...
If you are talking about calibrating the PGM meters that's the wrong section of the manual. I think you are referring to section 1-4-1 which is just verifying the mic amps are passing signal to the ACCESS SEND jack.
You want section 1-4-6 which tests the signal passage from the PGM BUSS IN jacks to the PGM BUSS OUT jacks and includes the meter cal instructions.
What is your meter's AC voltage accuracy at 1kHz? Do you need help finding that?
For signal generation I just use the Signal Gen app for my iPhone and verify the frequency and set/read the level using my Fluke 85 meter. I think the iPhone app is good enough for basic sine wave level set stuff 100Hz to 10kHz. I use the headphone out on my iPhone 6s. If it was more critical work I'd look for a dedicated analog signal generator, or a stop-gap would be to use my Guitarjack2 interface for the iPhone...cleaner and quieter output.
But anyway, step 1 is to verify your meter can accurately read AC voltage at 1kHz, verify your signal generator setup is adequate, and then execute the meter cal procedure in section 1-4-6.
garww
New member
I 've had lucas electronics on my old bonneville : ) Not too long after that I was tuning bikes like that by the exhaust. The bonny was 2 into one pipes so that wouldn't work !
So happens I actually got around to play a tape around 5pm today. It's kicking butt at 3 3/4 on second half of a Hendrix-Axis dub from one of the first 180 gram phase of re-issue trend
No, I'm not, particularly, troubled with electronics, bikes, computers, or cameras, etc
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mr.blisset
New member
well my tests with the DMM seem to confim the ac spec listed - 0.8%(45-1kHz) or 1.2%(1kHz-10kHz) AC Voltage accuracy) so this is good news. I tested it with tones coming from protools through apogee d/a. At 400hz it read 0.2989 so im thinking I probably need to get an mrl tape now.
Unfortunately my e-manual seems to be missing a page! I was hoping you might be able to help me out with steps for 1-4-6 sweetbeats? I've downloaded a few different manuals and they all have the same pages missing. I'm going to order a service manual from ebay.
Yeah garwww and ecc83 - how much time I want to invest in maintenance is something i've been thinking about. At this stage i'm happy to be learning the basics but not sure how far ill go with electronic theory. I've watched some youtube videos on how to use a multimeter How to use a Multimeter for beginners: Part 1 - Voltage measurement / Multimeter tutorial - YouTube <- I like this persons videos the best. Just by watching these I've learnt a lot about voltage and current etc. the basics.
There's a guy near me selling an analog oscilloscope cheap and wants it to go to a young person interested in guitar amps etc which is a good opportunity I should probably take advantage of. I've been thinking it would be nice to have one just to check the phasing of my mics on drums. and of course from what I understand they are a good thing to have around when using analog gear. hmm.
Unfortunately my e-manual seems to be missing a page! I was hoping you might be able to help me out with steps for 1-4-6 sweetbeats? I've downloaded a few different manuals and they all have the same pages missing. I'm going to order a service manual from ebay.
Yeah garwww and ecc83 - how much time I want to invest in maintenance is something i've been thinking about. At this stage i'm happy to be learning the basics but not sure how far ill go with electronic theory. I've watched some youtube videos on how to use a multimeter How to use a Multimeter for beginners: Part 1 - Voltage measurement / Multimeter tutorial - YouTube <- I like this persons videos the best. Just by watching these I've learnt a lot about voltage and current etc. the basics.
There's a guy near me selling an analog oscilloscope cheap and wants it to go to a young person interested in guitar amps etc which is a good opportunity I should probably take advantage of. I've been thinking it would be nice to have one just to check the phasing of my mics on drums. and of course from what I understand they are a good thing to have around when using analog gear. hmm.
sweetbeats
Reel deep thoughts...
A quick google search revealed this posted copy of the 388 manual that includes section 1-4-6:
http://reel2reeltexas.com/Tascam388Manual.pdf
You have a way to adjust the output of your PC-based signal generator, yes?
What make/model is the oscilloscope?
mr.blisset
New member
thanks for that however maybe something is wrong with my computer software because the page in that one is blank too? It jumps straight from 1-4-4 to 1-4-9 and there's a blank page in the middle. Do you have this problem? Maybe I need to try on another computer if this is the case.
Yes I can adjust the output in the utility plugin of protools. Is there anything I should be careful of to not give a false reading? Everything seemed to work fine when testing the multimeter at differing db levels.
Funny garwww should post that picture as the oscilloscope is a Leader LBO 522. It's in good condition and working fine apparently. He wants $40 for it but seems more like he wants to help someone starting out with amp building, guitar pedals etc
You can make a very useful 'output stage' for the soundcard with a good quality 10k log pot feeding a decent op amp as a follower (or even a bit of gain) This will deliver a Zout close to zero so you can make up a 600R feed resistor and then use readily available data to make an attenuator network.
The electronics smarts you need to have are not rocketry Mr B! The ability to follow some simple schematics and solder will do! I can't see you going far with tape machines unless you learn some of this WTGR.
Dave.
And you can only GATHER evidence with some understanding and measurement. (Lord K again)
Dave.
sweetbeats
Reel deep thoughts...
Yes I think you should try it on a different computer. I'm looking at it no problem on my iPhone.
mr.blisset
New member
well gee this is strange. the page is also blank on my iphone. I just tried another computer and blank there also! I wonder why it works for you? I've zoomed in and out and tried a few different things. bummer. I was really keen on getting into this today!
sweetbeats
Reel deep thoughts...
Oh I think I see what's going on...there is pretty much one not-so-good version of the 388 manual posted all over the place online. The pages are out of order. Section 1-4-6 is on page 111 of the PDF I linked above. Try that.