How much current does your bass preamp use

[line6man]

Originally Posted by Munjibunga

Oh, I know. I really bugs me, though. It's not uicroamps, is it.

No, it's uicroAmperes.

[bassbenj]

Originally Posted by mrbaloo

Now the updated list looks like this:

• Peavey Cirrus 5 FL (Made in USA): 11.21 mA
• Peavey Cirrus 5 (Made in USA): 10.10 mA
• Peavey DynaBass type preamps (Dyna, Sarzo, TL-5): 7.5 mA
• Peavey Cirrus 5 BXP: 4.72 mA
• EMG BTC with two OPA1611s: 3.6 mA
• Dean Edge 4: 2.01 mA
• Audere JZ3 preamp: 1.66 mA
• Ibanez SR2010 Ashula Bass: 0.79 mA
• Ibanez SR505: 0.75 mA
• Ibanez SR305m (EMG BQC preamp): 0.74 mA
• Fender MIM Deluxe Jazz: 0.55 mA
• Musicman Stingray (3-band EQ): 0.36 mA

I added measurement data of the MM SR right now.

/mrbaloo

I really am surprised at what current hogs Peavey Cirrus are! 10 ma is pretty high. That's about like running a bright LED! And there is a reason basses don't have power LEDs on them!

On the other hand, Stingrays are famous for using next to no current. And measurements seem to hold for that too.

[Smilodon]

Originally Posted by SGD Lutherie

There's lots of old capacitors that were marked "MF" instead of µF.

<snip>

So, mega farad? Impressive.

Originally Posted by SGD Lutherie

Yes. 1 microampere = 0.001 milliamperes

So 250µA = 0.25 mA.

I actually didn't look carefully enough to see it was listed as 0.25mA!

My bad.

Since we are very pedantic here already:

250µA is not the same as 0.25mA

250µA is the same as 0.250mA


Don't forget those sig figs.

[Technicality]

G&L L2000 Tribute

0.17mA (168.9µA to be precise)

I felt a bit embarrassed about measuring the lowest value so far, so since I've not changed the battery in forever I wondered if a preamp with a battery on the way out where the voltage had started to dip would draw less?

To make sure I measured the voltage across the battery under load (8.07v) and re-checked. Seems like it has a really low current draw after all, or my multimeter is lying to me.

[SGD Lutherie]

Originally Posted by Smilodon

Since we are very pedantic here already:

250µA is not the same as 0.25mA

250µA is the same as 0.250mA

Not here is isn't:

http://www.convertunits.com/from/microamps/to/milliamps

My calculator also resolves 250 X .001 as .25

[khutch]

Originally Posted by line6man

No, it's uicroAmperes.

Actually it is microAmperes, not uicroAmperes, not muicroAmperes!!

A value of 250uA (sorry, too lazy to find the mu) may or may not be the same as 0.25mA. It is ambiguous because no one knows if the 0 in the 250 is significant or just a required placeholder.

So, why don't we skip the semantics and return to the real purpose of this thread which could prove useful to a lot of people. I'm trying to remember to get better measurements of the currents of my two basses, the ones I gave are close but from memory.

Ken

[SGD Lutherie]

Originally Posted by khutch

A value of 250uA (sorry, too lazy to find the mu) may or may not be the same as 0.25mA. It is ambiguous because no one knows if the 0 in the 250 is significant or just a required placeholder.

It's a decimal, so it could be written as 0.2500000000 and it's exactly the same thing. That's why calculators drop that zero.

It's like that with money. .50 is the same as .5 and is half a dollar. .500 is also half of 1.

[khutch]

Originally Posted by SGD Lutherie

It's a decimal, so it could be written as 0.2500000000 and it's exactly the same thing. That's why calculators drop that zero.

It's like that with money. .50 is the same as .5 and is half a dollar. .500 is also half of 1.

To most people, yes. But scientists and engineers use numbers a little differently. If I tell you that the value is 250.0 then you know that I measured it to an accuracy of +/-0.05. So if I tell you that a quantity has the value 0.2500000, you know that it is a considerably more precise measurement than if I tell you the value is 0.25 because I don't type the extra zeros unless they mean something. Actually there is a way to indicate that a value is 250 +/- 0.5 rather than 250 +/-5 and that is to write the former value as 250. but not all that many people religiously follow this convention. If you see a value of 250. uA then it is equivalent to 0.250 mA whereas a value of 250 uA is equivalent to 0.25 mA -- but only if you are confident that the person conveying the information is using the standard scientific numerical reporting convention.

Ken

[SGD Lutherie]

Originally Posted by khutch

To most people, yes. But scientists and engineers use numbers a little differently. If I tell you that the value is 250.0 then you know that I measured it to an accuracy of +/-0.05. So if I tell you that a quantity has the value 0.2500000, you know that it is a considerably more precise measurement than if I tell you the value is 0.25 because I don't type the extra zeros unless they mean something. Actually there is a way to indicate that a value is 250 +/- 0.5 rather than 250 +/-5 and that is to write the former value as 250. but not all that many people religiously follow this convention. If you see a value of 250. uA then it is equivalent to 0.250 mA whereas a value of 250 uA is equivalent to 0.25 mA -- but only if you are confident that the person conveying the information is using the standard scientific numerical reporting convention.

Ken

Right, but if the trailing numbers are zeros, than it makes no difference. If you are rounding .050734 to .05 than you have changed the number.

If you remove the decimal point, then the difference between 25mA and 250mA is a big. With the decimal it's where the zero is that's important. But you know that. So .25 is very different from .025, but .0250 and .025 are not, unless there are other non zero numbers at the end.

[ctmullins]

Stupid question - how do you measure this? I'm thinking I can insert a stereo cord, then put an ammeter between the ring and sleeve on the other end - would that work?

[SGD Lutherie]

Originally Posted by ctmullins

Stupid question - how do you measure this? I'm thinking I can insert a stereo cord, then put an ammeter between the ring and sleeve on the other end - would that work?

Yes.

[aborgman]

Originally Posted by SGD Lutherie

There's lots of old capacitors that were marked "MF" instead of µF.

...and MMF instead of pF.

[Munjibunga]

This thread is fully infested with pedants.

[MontzterMash]

Originally Posted by SGD Lutherie

Right, but if the trailing numbers are zeros, than it makes no difference. If you are rounding .050734 to .05 than you have changed the number.

If you remove the decimal point, then the difference between 25mA and 250mA is a big. With the decimal it's where the zero is that's important. But you know that. So .25 is very different from .025, but .0250 and .025 are not, unless there are other non zero numbers at the end.

Actually, Ken's right. They are different:

http://en.wikipedia.org/wiki/Significant_figures

[SGD Lutherie]

Originally Posted by MontzterMash

Actually, Ken's right. They are different:

http://en.wikipedia.org/wiki/Significant_figures

leading and trailing zeros which are merely placeholders to indicate the scale of the number.

Since they are all zeros the lack of them has not changed the number, but you are seeing what looks like a lower resolution. You can go ahead and add them in, and nothing has changed.

In this particular case it doesn't matter, but I understand why it's done.

[ctmullins]

Originally Posted by MontzterMash

Actually, Ken's right. They are different:

http://en.wikipedia.org/wiki/Significant_figures

To be pedantic, they're not mathematically different, but the scientific accuracy implied is different.

[SGD Lutherie]

Originally Posted by ctmullins

To be pedantic, they're not mathematically different, but the scientific accuracy implied is different.

I agree.

But in this case it's moot.

[mrbaloo]

Originally Posted by Technicality

G&L L2000 Tribute

0.17mA (168.9µA to be precise)

I felt a bit embarrassed about measuring the lowest value so far, so since I've not changed the battery in forever I wondered if a preamp with a battery on the way out where the voltage had started to dip would draw less?

To make sure I measured the voltage across the battery under load (8.07v) and re-checked. Seems like it has a really low current draw after all, or my multimeter is lying to me.

Thank you!

Updated list:

• Peavey Cirrus 5 FL (Made in USA): 11.21 mA
• Peavey Cirrus 5 (Made in USA): 10.10 mA
• Peavey DynaBass type preamps (Dyna, Sarzo, TL-5): 7.5 mA
• Peavey Cirrus 5 BXP: 4.72 mA
• EMG BTC with two OPA1611s: 3.6 mA
• Dean Edge 4: 2.01 mA
• Audere JZ3 preamp: 1.66 mA
• Ibanez SR2010 Ashula Bass: 0.79 mA
• Ibanez SR505: 0.75 mA
• Ibanez SR305m (EMG BQC preamp): 0.74 mA
• Fender MIM Deluxe Jazz: 0.55 mA
• Musicman Stingray (3-band EQ): 0.36 mA
• MM 2-band preamp with LM4250 op amp: 0.25 mA
• G&L L2000 Tribute: 0.17 mA

Frankly, I don't bother the last third decimal of the measured values. My only interest is to compare the different current draws in different basses. Two decimals are enough. Beleave it or not...

/mrbaloo

[khutch]

Originally Posted by SGD Lutherie

So .25 is very different from .025, but .0250 and .025 are not, unless there are other non zero numbers at the end.

The key point, which I am not sure you (or Wikipedia) understand, is that 0 can be a significant digit, or it can merely be a placeholder. The only way to distinguish a value that was measured to be 0.250 from values that were measured to be 0.249 and 0.251 is to report the 0 according to the convention that scientists and engineers use. Using the scientific convention a number does not have to be non zero to be significant, even the zeros are significant. You seem to be claiming that 0 is always a placeholder, it is not. A reported value of 0.250 implies that ten times the precision was used compared to a value that is reported to be 0.25

Ken

[SGD Lutherie]

Originally Posted by khutch

The key point, which I am not sure you (or Wikipedia) understand, is that 0 can be a significant digit, or it can merely be a placeholder. The only way to distinguish a value that was measured to be 0.250 from values that were measured to be 0.249 and 0.251 is to report the 0 according to the convention that scientists and engineers use. Using the scientific convention a number does not have to be non zero to be significant, even the zeros are significant. You seem to be claiming that 0 is always a placeholder, it is not. A reported value of 0.250 implies that ten times the precision was used compared to a value that is reported to be 0.25

Ken

In this particulate case we are talking about converted between units of current consumption. I stated the published consumption of the op amp in question as used in the circuit. They list it as 250µA. If you want to convert that to mA than the answer is .25mA. If the current consumption was listed as 254.73µF, then you would need more places in your converted number.

Obviously in real life meters go to several decimal points, and the better ones have more places to be more accurate.

But we weren't talking about a real time measurement, we were talking abut converting units. In that case the answer is correct. Adding decimal places won't add anything to out measurement.

The rest is merely pedantic.