sweetbeats
Reel deep thoughts...
It doesn't specify, but it's built into the procedure. The measurement is being taken after the tone generator is connected, so it's loaded by default if you follow the procedure.
j.harv
@#$%
Thanks guys!
I'll take a pic of the meter when I get home today.
Also I am measuring from the PGM out.
I'm using a 1/8 stereo plug with rca plugs at the other end. Hope that's correct.
I'll take a pic of the meter when I get home today.
Also I am measuring from the PGM out.
I'm using a 1/8 stereo plug with rca plugs at the other end. Hope that's correct.
A Reel Person
It's Too Funky in Here!!!
...
I always used a standard (stereo) RCA cable, with alligator clip leads from the end of the RCA to the meter probes.
You should be alright. Measuring on the end of the 1/8" stereo plug might be a little awkward.
I always used a standard (stereo) RCA cable, with alligator clip leads from the end of the RCA to the meter probes.
You should be alright. Measuring on the end of the 1/8" stereo plug might be a little awkward.
sweetbeats
Reel deep thoughts...
J.harv I was going to say I have a set of leads for my Fluke meter with nice clip ends...makes it easier. Not necessary but nice.
I'm sure you need to turn up the volume on the PC.
You're fine using that 1/8" TRS to dual RCA "Y" cable...sounds like you are doing everything correctly, just need to increase the output of the tone generator and you should be on your way, but yes a pic of your multimeter should confirm my suspicions.
I'm sure you need to turn up the volume on the PC.
You're fine using that 1/8" TRS to dual RCA "Y" cable...sounds like you are doing everything correctly, just need to increase the output of the tone generator and you should be on your way, but yes a pic of your multimeter should confirm my suspicions.
j.harv
@#$%
Ok.
Here's a picture of the meter reading.
But........is this right.??? It reads .0311
I just noticed this. Im guessing this is different from 0.311.
Here's a picture of the meter reading.
But........is this right.??? It reads .0311
I just noticed this. Im guessing this is different from 0.311.
j.harv
@#$%
Alrighty then!
Well I was reading this thing wrong! Obviously
I managed to get a .316 reading on the meter through PGM1 in/out by having to set the tone generators volume output to 0db and by having the 388 pgm master fader right around the top of the shaded area.Now...this is through the 388. If I measure that same tone straight from my laptop I get .2368 So I had to use the pgm master fader to raise it up to .316
So Im not sure if this is gonna be accurate. The tone generator output level is at full as is my laptop volume control so I only get .2368. on the meter.Any how...PGM 1&2 read .316 and the meters needed a slight adjustment.I went through all the other pgm ins/out and they all read differently
PGM3= .313 PGM4= .312 PGM5= .3125 PGM6=.3205 PGM7=.319 PGM8=.310
So I didn't adjust the meters for those because Im not sure what to do with these different readouts.
I'd like to get an nice even accurate reading across the board without having to move faders around.
Is there a reason some of these other channels are out a bit???
Well I was reading this thing wrong! Obviously
I managed to get a .316 reading on the meter through PGM1 in/out by having to set the tone generators volume output to 0db and by having the 388 pgm master fader right around the top of the shaded area.Now...this is through the 388. If I measure that same tone straight from my laptop I get .2368 So I had to use the pgm master fader to raise it up to .316
So Im not sure if this is gonna be accurate. The tone generator output level is at full as is my laptop volume control so I only get .2368. on the meter.Any how...PGM 1&2 read .316 and the meters needed a slight adjustment.I went through all the other pgm ins/out and they all read differently
PGM3= .313 PGM4= .312 PGM5= .3125 PGM6=.3205 PGM7=.319 PGM8=.310
So I didn't adjust the meters for those because Im not sure what to do with these different readouts.
I'd like to get an nice even accurate reading across the board without having to move faders around.
Is there a reason some of these other channels are out a bit???
A Reel Person
It's Too Funky in Here!!!
Checked the manual. Here's my take on it.
If your test signal is patched to PGM IN & your DVM reading is on the PGM OUT, you'd adjust the PGM Master fader to achieve 0.316V on the output. If you had a 0.316V input signal, verified, then your PGM Master fader should be somewhere in the shaded area (7-8), but in your case with your lower than nominal input signal, your PGM Master fader might be riding a little high. However, when you measure 0.316V on the output, that's what you adjust your meter to, for 0VU.
Each PGM In, Line In, Mic In jack may have a slightly different sensitivity, probably due to components aging out of their specs, but you should not suffer minor preliminary differences in the readings as such, because you are expected to manipulate the top panel controls to compensate for minor differences. In many cases on a mixer like this, there are no fine adjustment pots or controls internally to compensate for these minor differences of inputs and/or other parts of the signal chain. The top panel control is the adjustment to manipulate til you get whatever output signal you want. In practical use in the studio, and in process or setup of a lot of these tests & calibrations.
The real point at this stage of the game is that if/when your PGM meter reads 0VU, you also have a true 0.316V on the PGM outputs, and vice versa. The difference between .312V and .316V is very small, but it is clearly readable on the DVM and VU meter. In this case you compensate with the PGM Master fader, adjust to get it all in spec,... read the output, set the meter,... 1-8, bang them out & move on.
It's important that you know you can trust your meters that when the needle is on 0 you're verified of having a known output level. There are many more adjustments to come in this regard, but this is one of the first ones to set you up going downstream.
If you're very careful at each stage, e'thing should line up nicely when all's said & done.
If your test signal is patched to PGM IN & your DVM reading is on the PGM OUT, you'd adjust the PGM Master fader to achieve 0.316V on the output. If you had a 0.316V input signal, verified, then your PGM Master fader should be somewhere in the shaded area (7-8), but in your case with your lower than nominal input signal, your PGM Master fader might be riding a little high. However, when you measure 0.316V on the output, that's what you adjust your meter to, for 0VU.
Each PGM In, Line In, Mic In jack may have a slightly different sensitivity, probably due to components aging out of their specs, but you should not suffer minor preliminary differences in the readings as such, because you are expected to manipulate the top panel controls to compensate for minor differences. In many cases on a mixer like this, there are no fine adjustment pots or controls internally to compensate for these minor differences of inputs and/or other parts of the signal chain. The top panel control is the adjustment to manipulate til you get whatever output signal you want. In practical use in the studio, and in process or setup of a lot of these tests & calibrations.
The real point at this stage of the game is that if/when your PGM meter reads 0VU, you also have a true 0.316V on the PGM outputs, and vice versa. The difference between .312V and .316V is very small, but it is clearly readable on the DVM and VU meter. In this case you compensate with the PGM Master fader, adjust to get it all in spec,... read the output, set the meter,... 1-8, bang them out & move on.
It's important that you know you can trust your meters that when the needle is on 0 you're verified of having a known output level. There are many more adjustments to come in this regard, but this is one of the first ones to set you up going downstream.
If you're very careful at each stage, e'thing should line up nicely when all's said & done.
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A Reel Person
It's Too Funky in Here!!!
Now I have a question:...
Can anyone tell me by this spec if my Fluke 77 Series II meter has "true RMS" capable readings?
I can't figure it out, however I notice a slight dip in reading higher frequencies in use. In the turnaround I use mostly 1K signals on critical adjustments. :/
Thanks
My reading is it's accurate only to 1kHz, and not spec'd for accuracy beyond that, which is why my high frequency readings vary a little lower. :/
Can anyone tell me by this spec if my Fluke 77 Series II meter has "true RMS" capable readings?
I can't figure it out, however I notice a slight dip in reading higher frequencies in use. In the turnaround I use mostly 1K signals on critical adjustments. :/
Thanks
My reading is it's accurate only to 1kHz, and not spec'd for accuracy beyond that, which is why my high frequency readings vary a little lower. :/
Attachments
sweetbeats
Reel deep thoughts...
No.
The output from the laptop to the 388 must be at or near 316mV. You will need to find a way to boost that output then from the laptop. The whole point of this is the signal from the tone generator must be at the calibration level of -10dBV coming into the 388.
Also, don't worry about minor variances at the outputs when one output is at 316mV. As you know the PGM MASTER faders gang 4 busses together each...that's 4 separate resistive elements, 4 separate wipers...there's no way they are all going to match exactly...+/-5mV variance...even +/-10mV variance is not something I'd be concerned about. You're fine.
j.harv
@#$%
Just boosted the the signal with a little 4 channel headphone amp that I forgot I had.
So now Im getting .316 from the laptop
Now to go through the meters again.
So now Im getting .316 from the laptop
Now to go through the meters again.
j.harv
@#$%
Got the pgm faders(vu's) to all line up.
Some minor variance on the outputs.Especially pgm 8. That was around .320
Now with the master faders.I go the left outputing .316 or very close. But the right,with the same signal going in,is coming out with .312-ish and the vu meter is reading -1 db. So im guessing this is not bad and I should adjust the meter to 0db even if its spitting out around .311-12 ???
Some minor variance on the outputs.Especially pgm 8. That was around .320
Now with the master faders.I go the left outputing .316 or very close. But the right,with the same signal going in,is coming out with .312-ish and the vu meter is reading -1 db. So im guessing this is not bad and I should adjust the meter to 0db even if its spitting out around .311-12 ???
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sweetbeats
Reel deep thoughts...
Cool. Post an update. Starting to sink in better?
Good job working through it. And the good news is that the procedure with which you now have some familiarity is the same basic procedure you're going to use for much of the remaining calibration steps.
Good job working through it. And the good news is that the procedure with which you now have some familiarity is the same basic procedure you're going to use for much of the remaining calibration steps.
sweetbeats
Reel deep thoughts...
Yes. Remember, -20VU was 10x less voltage...a few mVs ain't gonna make squat of difference to the reading on the meter. Like I said earlier even +/-10mV variation wouldn't bother me. Line those meters up, man!
j.harv
@#$%
Great! Thanks for all the help.
Im guessing the next step being as I don't have a test tape yet would be adjusting the recording level??? Step 1-5-5.
Anyhow...I'll get to that tommorow.Gotta go chop some wood
Im guessing the next step being as I don't have a test tape yet would be adjusting the recording level??? Step 1-5-5.
Anyhow...I'll get to that tommorow.Gotta go chop some wood
j.harv
@#$%
On quick question.Is 400 hz the same as 1000k.?
The reason I ask is that on the service chart on page 1-28 is listing 400hz as the tone in some of the steps that i have already done using 1000k.
Just a little confusing
The reason I ask is that on the service chart on page 1-28 is listing 400hz as the tone in some of the steps that i have already done using 1000k.
Just a little confusing
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S
skywaveTDR
Active member
Many good answers here. From a Teac technician standpoint the 388 is one of the more difficult units to work on due to the size and layout of the deck and is one of the few I refuse to take in because I do not have the room to work on those monsters. Getting a Tape from MRL, Full Compass or JRF is all the same tape from MRL. No one I know is making alignment tapes other than MRL. The largest problem with the 388 and you might find this out when you get your tape is the frequency response of the head- as they wear they start to lose high end response and once they can not be adjusted to play back the test tape in a flat frequency manner then the jig is up. This is why I advise people to avoid this unit as John French has told me there are no heads for these machines and the Fostex heads are also not available.
In a conversation I had with John, it is clear that the use of the open Reel deck Tascam 38 is a much better choice as a minimum to use as they still have new heads for them and they do not have all the problems the 388 has had. Anytime you get into real tight head/track placement like that the tolerance for sloppiness gets less and less. This then means the head will fall out of specs faster than on a 38.
Also the required tape for the deck is no longer made but a good substitution would be the RMGI LPR35.
I try to educate people when they call me but some of them do not listen and find out the hard way- I have been dealing with these machines for better than 40 years so I have some direct knowledge of the workings of them. I still work on decks all the time and have a Tascam 48 on my bench now.
In a conversation I had with John, it is clear that the use of the open Reel deck Tascam 38 is a much better choice as a minimum to use as they still have new heads for them and they do not have all the problems the 388 has had. Anytime you get into real tight head/track placement like that the tolerance for sloppiness gets less and less. This then means the head will fall out of specs faster than on a 38.
Also the required tape for the deck is no longer made but a good substitution would be the RMGI LPR35.
I try to educate people when they call me but some of them do not listen and find out the hard way- I have been dealing with these machines for better than 40 years so I have some direct knowledge of the workings of them. I still work on decks all the time and have a Tascam 48 on my bench now.
S
skywaveTDR
Active member
In most cases they can be considered the same although due to equalization curve there is a little difference. I use 1KHz all the time but the reason is the dBx decks. The 1 KHz tone is the frequency of calibration for the dBx system so that is why I use it to get deck exactly on 0 Vu then the pressing of the dBx button just shows me the encode or decode error to be dealt with. You can use 1KHz pretty muh the same as 400Hz. Keep in mind 1K is 1000Hz while your 1000K is 1 MHz and that does not go through a tape deck. I understand what you mean but just wanted to point that out
j.harv
@#$%
Thanks for the info Skywave.
I know about the heads no longer being available for this unit. Kinda sucks...I really like the 388.This is my second 388 that Im doing a basic set up on.My 388 that is in use is still hooked up in my basement studio.So I want to swap them.My second one has far less head wear on it.Looks like they have quite a bit of life left in them and I'd like to put it through its paces.Then bring my other one up and go through that one.
I know about the heads no longer being available for this unit. Kinda sucks...I really like the 388.This is my second 388 that Im doing a basic set up on.My 388 that is in use is still hooked up in my basement studio.So I want to swap them.My second one has far less head wear on it.Looks like they have quite a bit of life left in them and I'd like to put it through its paces.Then bring my other one up and go through that one.
j.harv
@#$%
Just an update.....
Just did the recording level check.Step 1-5-5.
400hz tone at -10db into pgm buss.Recorded that for 30 seconds.Played back and pgm1 meter pinned for the whole 30sec.
I guess this is not right??? Also the measurement from the pgm out was way high and it wouldn't adjust by tweeking trim R143.
Just did the recording level check.Step 1-5-5.
400hz tone at -10db into pgm buss.Recorded that for 30 seconds.Played back and pgm1 meter pinned for the whole 30sec.
I guess this is not right??? Also the measurement from the pgm out was way high and it wouldn't adjust by tweeking trim R143.
A Reel Person
It's Too Funky in Here!!!
At this point,...
You can go back thru and verify your PGM In>PGM Out measurement and VU meter adjustments, & adjust if necessary.
At that point you halt & don't know exactly what you have until you get your MRL tape. The playback and/or record levels could be all out of whack. Until you run the MRL, you don't know exactly what you're dealing with.
You can go back thru and verify your PGM In>PGM Out measurement and VU meter adjustments, & adjust if necessary.
At that point you halt & don't know exactly what you have until you get your MRL tape. The playback and/or record levels could be all out of whack. Until you run the MRL, you don't know exactly what you're dealing with.