HI-Z DB Meter?

[FTL_Ian]

The manual for the Broadcast Tools ACS 8.2 says I need one of these to check the levels of each input.

Adjusting Input and Output Levels:
Calibrating audio levels on the switcher and VU meters:
1 - Remove power from the unit.
2 - Remove the cover.
3 - Feed a reference signal into the selected input channel.
4 - Connect a Hi Z dB meter to the TEST jack TB9
5 - Reapply power.
6 - Adjust the left and right input to a zero level on your dB meter.
7 - Adjust the VU trimmers R126 (left) and R133 (right) for zero VU.
8 - Now the output trimmers may be used to set the desired output levels.

These seem to be quite expensive ($800). Is there a more affordable way to check the input levels of this device?

 

[RolfTaylor]

Well, I would check with B'tools for sure, but I suspect what they are saying is NOT a 600 Ohm dBm meter.

Most meters meters have a high enough impedance they should get you close.

The manual for the Broadcast Tools ACS 8.2 says I need one of these to check the levels of each input.

Adjusting Input and Output Levels:
Calibrating audio levels on the switcher and VU meters:
1 - Remove power from the unit.
2 - Remove the cover.
3 - Feed a reference signal into the selected input channel.
4 - Connect a Hi Z dB meter to the TEST jack TB9
5 - Reapply power.
6 - Adjust the left and right input to a zero level on your dB meter.
7 - Adjust the VU trimmers R126 (left) and R133 (right) for zero VU.
8 - Now the output trimmers may be used to set the desired output levels.

These seem to be quite expensive ($800). Is there a more affordable way to check the input levels of this device?

 

[FTL_Ian]

Well, I would check with B'tools for sure, but I suspect what they are saying is NOT a 600 Ohm dBm meter.

Most meters meters have a high enough impedance they should get you close.

Can you point me to one that is affordable? Thanks!

 

[RolfTaylor]

Here you go.

Radio Shack:
Compact 18-Range Multitester
Model: No model information available | Catalog #: 22-223

I have deliberately recommended an analog model.

 

[FTL_Ian]

I already have a digital multitester. How would one use such a device to measure audio levels? Thanks for your patience with my inexperience.

 

[rrsounds]

I already have a digital multitester. How would one use such a device to measure audio levels? Thanks for your patience with my inexperience.

Some digital meters have a dB scale, but they're usually a bit more expensive. An analog meter is much better at portraying _trends_ than a digital meter, but in this case either will work. I think the manufacturer just wants the measuring device to have a minimal influence upon the level, hence "Hi Z".

You can use any meter that has an accurate AC scale. It's not clear, but I am guessing the "zero" they're looking for is zero dBu, or 0.775V.

Level measurement terminology is full of inconsistencies, confusing abbreviations and multiple 'standards.' Check Wikipedia or Google for more info if you're curious.

Kind Regards,
David

 

[littlejohn]

If you already have a Simpson 260, use it. Scales and correction factor are on it. If not, consider buying one. It is the Bull Goose VOM, and you'll find 90 % of what you want to measure will measure on it quite will.

 

[SFM-Ptgal]

Here you go.

Radio Shack:
Compact 18-Range Multitester
Model: No model information available | Catalog #: 22-223

I have deliberately recommended an analog model.

So, ANY multimeter with an db scale can be used as an audio meter for tunning tape recorders, for example?
I find the scale graph so tight that won't be easy do correct readings on a analog multimeter

 

[RolfTaylor]

For static tones, yes, most meters will suffice, depending on the accuracy your require.

For dynamic levels you need a meter with specific dynamics depending on your need.

If you are measuring noise (e.g. to determine s/n) you need a meter with an appropriate filter. e.g. 20 to 15 or 20 kHz. Other wise out of band noise can make your noise look horrible.

Here you go.

Radio Shack:
Compact 18-Range Multitester
Model: No model information available | Catalog #: 22-223

I have deliberately recommended an analog model.

So, ANY multimeter with an db scale can be used as an audio meter for tunning tape recorders, for example?
I find the scale graph so tight that won't be easy do correct readings on a analog multimeter

 

[rrsounds]

For static tones, yes, most meters will suffice, depending on the accuracy your require.

For dynamic levels you need a meter with specific dynamics depending on your need.

If you are measuring noise (e.g. to determine s/n) you need a meter with an appropriate filter. e.g. 20 to 15 or 20 kHz. Other wise out of band noise can make your noise look horrible.

Here you go.

Radio Shack:
Compact 18-Range Multitester
Model: No model information available | Catalog #: 22-223

I have deliberately recommended an analog model.

So, ANY multimeter with an db scale can be used as an audio meter for tunning tape recorders, for example?
I find the scale graph so tight that won't be easy do correct readings on a analog multimeter

Even in this day and age, a real, honest-to-God analog VU meter comes in real handy some times. I have a pair of McCurdy test sets with both a VU meter and a PPM meter plus amplification and a variable attenuator that is pretty much worth its weight in silver, if not gold, when measuring analog audio.

I would add one thing to Rolf's useful comments, that is as far as noise measurements go, you will need a meter with considerable amplification, as a passive meter won't be sensitive enough to show noise. Of course, any test set that is specifically designed to measure noise would have the amplification along with (hopefully) filtering.

Kind Regards,
David

 

[FTL_Ian]

What setting do I put my multimeter on to read DB?

Thanks!

 

[littlejohn]

The lowest AC setting. The dB scale might say 0dB = whatever. And tell you how many dB to subtract/add for the other voltage settings.

 

[tom]

For a quick and dirty level meter - just use a mixer, like a
Radio Shack job, and make up a test lead to bridge across
your test points. You aren't interested in "exact" readings,
just a relative 100% reference so you can set all of your
inputs the same.

Adjust the input pot on the mixer so you get 100% at your test point
when it's at the level you want - then move the input and the meter
to all of the others and adjust the Broadcast Tools device to
the level you want.

Simple and free ... the input to a tape deck, cassette recorder,
even a PC with a sound program will achieve the desired results.

 

[FTL_Ian]

Thanks for all the help!

 

[SFM-Ptgal]

For a quick and dirty level meter - just use a mixer, like a
Radio Shack job, and make up a test lead to bridge across
your test points. You aren't interested in "exact" readings,
just a relative 100% reference so you can set all of your
inputs the same.

Adjust the input pot on the mixer so you get 100% at your test point
when it's at the level you want - then move the input and the meter
to all of the others and adjust the Broadcast Tools device to
the level you want.

Simple and free ... the input to a tape deck, cassette recorder,
even a PC with a sound program will achieve the desired results.

Since I'm not tech skilled sorry if I'm wrong: isn't there the risk of impedance mismatching disturbing the results?

 

[radiorob2.0]

For a quick and dirty level meter - just use a mixer, like a
Radio Shack job, and make up a test lead to bridge across
your test points. You aren't interested in "exact" readings,
just a relative 100% reference so you can set all of your
inputs the same.

Adjust the input pot on the mixer so you get 100% at your test point
when it's at the level you want - then move the input and the meter
to all of the others and adjust the Broadcast Tools device to
the level you want.

Simple and free ... the input to a tape deck, cassette recorder,
even a PC with a sound program will achieve the desired results.

Since I'm not tech skilled sorry if I'm wrong: isn't there the risk of impedance mismatching disturbing the results?

As he said, it's quick and dirty giving you an idea of your level.

 

[tom]

Since I'm not tech skilled sorry if I'm wrong: isn't there the risk of impedance mismatching disturbing the results?

No - impedance doesn't matter ... you will be using the SAME test meter on all
channels, so they will all be matched - which is the desired result.

Your "100%" is what matters.

... tom