Important Tape Calibration Question

  • Thread starter Thread starter thereelman77
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jpmorris said:
Aren't they inaccurate over 400Hz?
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they are innacurate above 120Hz in most cases of the cheap ones. Any DVM or voltmeter won't do it. It has to be a trueRMS with proper frequency range. The best bet is the leader LMV-181A, i bought mine for $40 and it is a great unit for this.
 
I have one of the upper-end Radio Shack DVM units (can't recall the model at the moment)...it was maybe $70(?) about 7-8 years ago...it's accurate, and also reads in dBm.
 
miroslav said:
I have one of the upper-end Radio Shack DVM units (can't recall the model at the moment)...it was maybe $70(?) about 7-8 years ago...it's accurate, and also reads in dBm.
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yes they exist. but not the standard for cheap DVMs. Too many people end up buying $20 DVMs assuming they can do TrueRMS up to 20 kHz. Always good to check the specs to make sure it is the case like in yours.
 
fgonza2 said:
yes they exist. but not the standard for cheap DVMs. Too many people end up buying $20 DVMs assuming they can do TrueRMS up to 20 kHz. Always good to check the specs to make sure it is the case like in yours.
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The one I had before I got the Fluke was only good up to 400Hz. Sadly I had to buy the thing first in order to find that out because it was buried deep inside the manual.
 
Ah good point, I rescind my suggestion there, I forgot about the cheapies being inaccurate above lower mids, but yeah, $40 can get a good DVOM, not all are created equal and yes you need to check the specs. It's a good general purpose piece of equipment to have in life anyway, as basic a toolbox item as hammers and screwdrivers IMHO.
 
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This is what it is.
 
So....What should I do. Because I'm trying to save for 1/4" MRL? Will that device be sufficient enough?
 
thereelman77 said:
So....What should I do. Because I'm trying to save for 1/4" MRL? Will that device be sufficient enough?
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I might be a little hard to read on that analog meter being that the reference voltage for -10db gear is pretty low. Dial the meter to 10 AC V it and see what you get at 1k then lower the tone to something like 100hz while keeping the tone's level the same and see if you get a very different reading. Interesting that it has a dB scale. Try your meter and and see what you get.

By the way, how is your machine SOUNDING now? Better, more consistent?
 
The machine is sounding better. It is more consistent. I have noticed that the "low end" buzz from the machine seems to be a bit louder than before, but I assume that, that is because it is actually calibrated.
 
thereelman77 said:
The machine is sounding better. It is more consistent. I have noticed that the "low end" buzz from the machine seems to be a bit louder than before, but I assume that, that is because it is actually calibrated.
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Do you mean a 60hz ground hum? Does your machine have a head shield? How long is your cabling?
 
Well it could be a 60hz ground hum, now that you mention it. It's really only noticeable when the deck is in standby. And we also built the wooden stand with it on a slight slant, would that affect it? We built it so that it's basically level when a person is sitting down in front of them. I'd say about 2 & 3/4' to 3' up. Cabling is whatever they built the plug to, 2/3 feet or whatever. Never used a extension cord with it. Plug it into a power strip most of the time, sometimes into a separate outlet from the wall.
As far as a head a shield, it has the one that lifts up & down for access for head maintenance, but if you mean does it have a shield in front of the heads, then no...

Part of it sounds like a 60hz ground hum, but the rest just sounds like noise from the deck.
 
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