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Post by ourclarioncall on Dec 5, 2019 16:10:06 GMT -5
Hi, beginner to understanding guitar electronics
I need recommendations for a multimeter ?
I don’t have a clue.
I’m seeing ones from £10 up to £300 (fluke is the high end brand)
I probably only need one for ten bucks but I’ve got expensive tastes lol
Maybe if folks could recommend something budget , something mid range and something high end , that would give me an idea.
Thanks
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Post by thetragichero on Dec 5, 2019 16:53:18 GMT -5
i wouldn't know specific shops in the uk to look in but things that you might find useful:
auto ranging - very helpful with unknown components especially until you learn resistor color codes/forthose 5band blue resistors i can never read correctly
transistor tester - helpful for determining unknown pinouts and transistor gain. this is a future need but once you dive into stompbox building you'll be glad you have it
ability to read resistance, capacitance, voltage along with continuity (probably the single most useful function when trying to diagnose issues). inductance can be handy but not nearly as important as the others. most likely will have current measurements but i rarely use that function
i have three multimeters: auto ranging radio shack that has everything but inductance and transistor tester (the capacitance measurements are wonky <1nf so i use another meter for that), an lcr meter i purchased when i thought i blew old faithful, and a cheap harbor freight meter i keep around for its transistor tester (although it doesn't seem to to register pnp and it'd be nice to have something that reads fets)
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Post by ourclarioncall on Dec 5, 2019 17:01:45 GMT -5
i wouldn't know specific shops in the uk to look in but things that you might find useful: auto ranging - very helpful with unknown components especially until you learn resistor color codes/forthose 5band blue resistors i can never read correctly transistor tester - helpful for determining unknown pinouts and transistor gain. this is a future need but once you dive into stompbox building you'll be glad you have it ability to read resistance, capacitance, voltage along with continuity (probably the single most useful function when trying to diagnose issues). inductance can be handy but not nearly as important as the others. most likely will have current measurements but i rarely use that function i have three multimeters: auto ranging radio shack that has everything but inductance and transistor tester (the capacitance measurements are wonky <1nf so i use another meter for that), an lcr meter i purchased when i thought i blew old faithful, and a cheap harbor freight meter i keep around for its transistor tester (although it doesn't seem to to register pnp and it'd be nice to have something that reads fets) Thanks, very helpful info. Yeah, I would rather spend a lot of money in the beginning and get something that will cover all the bases eBay or amazon are usually where you’ll find the best prices. I use eBay (.co.uk) a lot. So if a nice person said hey buddy, here’s 300 bucks, go buy a multimeter that can do everything you need it to, what would you go for ? |
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Post by thetragichero on Dec 5, 2019 17:43:55 GMT -5
50 bucks should be more than adequate. i think all three of my meters cost about that in aggregate
i will search around on Amazon and find some candidates, but don't take it as gospel as these other fellas might have specific units to suggest
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Post by ourclarioncall on Dec 5, 2019 18:18:40 GMT -5
50 bucks should be more than adequate. i think all three of my meters cost about that in aggregate i will search around on Amazon and find some candidates, but don't take it as gospel as these other fellas might have specific units to suggest Cool 😎. And no rush as any money I get in the next month will no doubt be going on Christmas presents for my 5 kids. Multimeters will prob be a 2020 purchase I see your in Florida? I visited Orlando about 20 years ago. I remember stepping off the plane and feeling the heat and thinking wow! First time I had been to a warm country. I have a few friends near Spring Hill and my wife’s uncle lived in port Arthur on the west coast I think it is. |
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Post by thetragichero on Dec 5, 2019 18:24:15 GMT -5
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Post by ourclarioncall on Dec 6, 2019 4:51:42 GMT -5
Thanks for the suggestions 👍 👍
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Post by ashcatlt on Dec 6, 2019 11:55:27 GMT -5
Impedance matters. For the things we do with these it really should be as high as possible. This isn’t always easy to find for a given meter, and I’m honestly not sure what a general range is, but I know I had to look at a couple before I settled on the one I got. Still shouldn’t be super expensive, but try to look at that.
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Post by reTrEaD on Dec 6, 2019 13:23:03 GMT -5
Impedance matters. For the things we do with these it really should be as high as possible. This isn’t always easy to find for a given meter, and I’m honestly not sure what a general range is, but I know I had to look at a couple before I settled on the one I got. Still shouldn’t be super expensive, but try to look at that. Sometimes it matters. And when it does, it matters a LOT. But unless one is delving inside a tube amp or a pedal with FETs, it usually doesn't matter at all. A high-quality VTVM or DVM is nice luxury but for average use around the house and beneath the pickguard, a bargain basement Digital multi-meter works just fine. guitarnuts2.proboards.com/post/81947/thread |
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Post by b4nj0 on Dec 6, 2019 16:17:05 GMT -5
I always assumed digital multimeters are very high impedance since they don't load the circuit under test. Moving coil meters are of low(er) impedance. Good examples of the latter are AVO 8s which are 20K ohms per volt and although they do load the circuit a little, often we can ignore it. (This doesn't apply to AVO 7s which are (from memory) 1K ohm per volt.
El cheapo moving coil meters frequently hover around 1K ohm per volt too (well they always used to) and like the AVO 7 do need consideration for circuit loading. I'm thinking of those 5 bucks Radio Shack abominations.) For general guitar work pretty much anything is useful (or at least better than nothing) but digital meters can be so inexpensive that unless there is a perceived need for reading unstable measurements, there's little point in a moving coil meter. Bearing that in mind, look for a digital bar graph facility in any digital meter (and ideally a display peak lock facility too.)
My own preference would be for an old Fluke 7X series- preferably a model 77, but like all old and venerable gear, they do command an unrealistically high price on eBay. It would lack many of the capabilities of modern DVMs but that wouldn't be a consideration for me. I have used an old (and accurate) Robin 4.5 digit non auto-ranging meter for well over 20 years. Unusually it came with a traceable calibration certificate which has long since expired. It's worth noting that "digital" doesn't automatically imply accuracy.
I never get out my trusty AVO 8. Stupid batteries inside those old warriors!
e&oe ...
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Post by ourclarioncall on Dec 6, 2019 18:13:47 GMT -5
Interesting video. A beginners journey into buying multimeters for working on guitar amps
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Post by ourclarioncall on Dec 6, 2019 18:42:23 GMT -5
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Post by b4nj0 on Dec 7, 2019 8:17:45 GMT -5
The YouTube video was pretty good and the guy spoke a lot of sense, but I thought he confused average with RMS at one stage?
e&oe ...
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Post by ourclarioncall on Dec 7, 2019 8:36:16 GMT -5
The YouTube video was pretty good and the guy spoke a lot of sense, but I thought he confused average with RMS at one stage? e&oe ...Hi, which video? The amp guy or the long one with the Australian guy ? I don’t even know what RMS stands for haha, so il take your word for it  |
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Post by b4nj0 on Dec 7, 2019 12:29:15 GMT -5
The amp guy.
RMS is "root-mean-square" (or more properly "square-mean-root" ...)
e&oe ...
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Post by ourclarioncall on Dec 7, 2019 13:59:22 GMT -5
The amp guy. RMS is "root-mean-square" (or more properly "square-mean-root" ...) e&oe ...Ah, gotcha. The other link is pretty good too. Well for a guy like me that has no clue about multimeters The guy has tons of videos |
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Post by sumgai on Dec 7, 2019 14:07:08 GMT -5
occ,
To be more specific, the RMS value of an AC voltage in a circuit will be approximately the same as if you had applied a DC voltage to that circuit in order to obtain the same results. (Results usually, but not always, being measured in watts consumed.) Ex. You apply a DC voltage of 20 vDC to a circuit, and it consumes 1/2 amp, giving a 10 watt consumption reading. In order get that same amount of work from an AC voltage, you need to apply 28 vAC(peak) to the circuit. The math for that is appended below.
What all of that means is that you sometimes (often!) encounter meters that don't read RMS, or use only a rough estimate of RMS, and the reading can lead to faulty results. In order to avoid that, you want a meter that does read in True RMS - but those are expensive, by comparison.
Fortunately for us in the guitar world (not the amp world), this doesn't affect us. In 99% of all cases under the pickguard, we're using the DMM for resistance measurements. As noted above, if the meter can also read capacitors and inductors, that's a neat feature, but by no means a necessary one. And again, meter price does not guarantee accuracy, but it does have a strong correlation.
I know you're dying to ask, so I'll volunteer the info: I have an older Fluke 187, a True RMS jobbie. It also has a ton of other features, but that's neither here nor there. Sadly, that particular model is long since discontinued, and the recommended replacement is the 287.... which will set you back more than $400, new. Used units are available, although they ain't cheap either. A better idea would be a Fluke 117, just a tad over $100, new.
But whatever you get, make sure of two things - the test leads are long enough (surprise, they don't reach!  ), and that you can attach small alligator clips to them. Many will be the times you wish to leave a lead attached to the same point for more than a moment, as you press the other lead to various points around the circuit. Alligator clips make this easy. Many test meters use the same input jacks for attaching the test leads, and wouldn't you know it, you can find and purchase test leads by themselves. You may wish to upgrade your test leads, who knows. (My Fluke leads are almost too long, they constantly get tangled and twisted around.  )
HTH
sumgai
Appendix A:
RMS is defined as the effective power of an alternating current flow (AC). To get this number, we must remember that AC goes from 0 volts to some peak number of volts, and back again to 0. And then it goes negative for the same number of peak volts. Lather, rinse and repeat.... ad finitum.
So what's that peak voltage? Well, to shortcut things and get to heart of the matter, RMS turns out to be 0.7 of the peak reading. (To be both more precise and more accurate, it's 0.7071 of that reading.) Now, is all of this really necessary to us in the guitar world. Not inside of our guitars, no. But inside of anything else (amp, stompbox, etc.), yes it does matter. Take a truly cheap meter and stick it in your Mains wall socket. You'll read something akin to 300 to 310 volts. In RMS terms, that would work out to 210 to 220 vAC. And to make it even worse, most meters just above that ultra-cheap price level won't tell you that they can't do True RMS, but they will say RMS on the box (or front panel, etc.). This means that they are doing an approximation, and they are almost universally wrong. What they're doing takes real computing power, on the order of a Alienware gaming machine compared to a Commodore 64. For that, you pay big bux. Net effect: they'll read about 0.8 of the peak, and call it good enough.
If you're gonna buy just one meter, and have it do everything for the foreseeable future, even the Fluke 117 might not be enough for you. But my advice would be to procure a cheap one now, something like those you see above, and obtain a better grade meter in the not-too-distant future. And that boils down to always having a second unit on hand, as a backup if nothing else. I do.
HTHT
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Post by ourclarioncall on Dec 7, 2019 18:05:43 GMT -5
In one of the vids I posted, an amp tech tells the story of his journey into multimeters. Being a rookie, he tells of the mistakes he made
His first purchase was a
Klein mm600 for $30. Its a good multimeters but not suited to guitar amps which he realised when he found out he needed to run a test signal at 10mV e 1kHz, and got strange readings. He realised his multimeter was only really good up to about 400 Hz. Any more than that and it’s not accurate at all.
So, his first rookie mistake, not realising different multimeters have different ranges, just thought they were all the same way.
One more important issue he states is that it is not true RMS because of the known formulas.
——
At this point he thought, well what multimeter will work for my application of guitar amps?
He hears everyone recommend the
FLUKE 87 v , but he doesn’t wan to pay 400$
Sooo.... he went for the FLUKE 117 from amazon for $150.... but realised although it is a fanstastic multimeter, it is more suited to electrician not for working on guitar amps because of the milliVolts range which down at 10 milliVolts wasn’t accurate
———-
Finally after second multimeter fail, he study’s the spec a bit closer and picks up a
AGILENT u1252b for $100 on eBay
He managed to find very detailed info from The company on ranges and accuracy , which he could not find for the other multimeters he had been working with . It was highly rated and also had true RMS
This is the one he uses, alongside an oscilloscope, and does the math conversions (0.7 and 1.41) for the RMS
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Post by ourclarioncall on Dec 7, 2019 18:12:48 GMT -5
So yeah,
It seems a bit of research pays off, and knowing what your intended use is
Guitar electronics is one field
And Guitar amps and stomp boxes is another
I do like the fluke range, I was checking them out on eBay . The go from 113 up to 117.
The 117 is £175 new , and another £75 for the lead/probe/clip set
Going into amp territory the FLUKE 87 V looks like a good option. £280 new
It will be quite a while before I hit amps. So I maybe progress from a cheapo to get going in the beginning , then the 117, then finally the 87 V .
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Post by sumgai on Dec 8, 2019 3:06:16 GMT -5
..... He realised his multimeter was only really good up to about 400 Hz. Any more than that and it’s not accurate at all. This is true for nearly all cheapies, because nearly all of them use the same chipset. To get up into the usable audio range, you gotta spend the moolah. Not sure where you were going with that statement. Was this meant to apply specifically to the Klein meter, or to all meters in general? Also, it's now evident that I missed an important point, the last time out. By using the words "True RMS", the implication is that the waveform need not be perfectly sinusoidal - it can be nearly any shape at all, and the meter will figure it out and give you a correct reading. Like I said before, that takes real computing power, with a commensurate up-tick in price. If a meter doesn't say "True RMS", then it's actually reading the peak voltage, and assuming it's a sinusoidal waveform. Obviously, if said waveform is not sinusoidal, then all bets are off. Which as Mr. Murphy would have it, is what happens almost all of the time in the guitar world. AEH! AEH! AEH! AEH! (Sound of Beaulah's Buzzer, from the old TV show Truth or Consequences.) I worked at Fluke about 45 years ago, long before hand-held meters were a thing. But even then, the cheaper benchtop meters made at Fluke were good down to 100 microvolts, at up to 1KHz. I can't imagine that Fluke would degrade their capabilies, let alone their reputation, just to make a hand-held meter. I'm calling BS on that one. (In addition, the cheapest model at the time, the 8000A, could read down to 100 nanoamps!! That's laboratory grade right there. And we won't get into the fact that it could do 19.99 milliOhms, will we....) Agilent is a good brand, pretty much on par with Fluke, feature for feature. But again, if one knows where to ask and what to ask for, one can easily find the specs on any piece of test equipment out there, trust me on that one. I suspect that his Google-fu was weak. Wait, excuse me - did you say that he's doing math conversions, after buying a quite decent meter?  According to the spec sheet, this thing is accurate plus or minus 1% + 60 counts over the entire frequency range from 20Hz to 100KHz - and this is at inputs of 1 mV! (The range and accuracy are reduced a bit, as the input voltage increases.) I'd have to go look, but I don't recall that my Fluke claims that resolution and accuracy. I don't think this guy is on the up and up, because if he's hitting the Peak button to get that voltage, only to whip out a calculator.... then why'd he buy such an expensive meter in the first place?
I also use an o'scope, it lets me see the actual waveform, and adjust things like the bias voltage for the cleanest signal possible. An old tech, or a young one that paid attention when an old tech was telling him something, knows how to use a scope to determine a capitor's value. (Hint: there are YouTube videos on how to do this, but when I was growing up, I had to pay attention to Uncle Elmer.)
HTH
sumgai
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Post by ourclarioncall on Dec 8, 2019 13:38:58 GMT -5
Sumgai
I think from about the 4 minute to 6 minute mark of the video posted above will clarify what he is saying about true RMS, calculations and oscilscope
Maybe I have butchered what he was saying , but maybe not 😬
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Post by ourclarioncall on Dec 8, 2019 13:41:26 GMT -5
Sumgai
Cool history . Did fluke give you free stuff when you worked there ?
I’m guessing they are an American company
Are they , were they the biggest name in this market ?
Is there a British equivalent that would be in the same league ?
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Post by JohnH on Dec 8, 2019 14:14:53 GMT -5
On multimeters, id say that 90% of what is useful is provided very adequately by the generic $15 meters that you find everywhere. So if in doubt, might as well just get one of those and start playing with it. If you get a better one later, then you have a spare.
But to step up from that, Id look for one with both capacitance and Inductance ranges. It is very interesting to be able to measure those, eg see the inductance of your pickups, capacitance of your cables etc. It helps with learning even if its not mil-spec tough or laboratory-grade accurate. I have a great one that I bought a few years ago new for $50
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Post by ourclarioncall on Jan 26, 2020 19:00:38 GMT -5
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Post by JohnH on Jan 26, 2020 20:14:59 GMT -5
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Post by ourclarioncall on Jan 26, 2020 21:22:21 GMT -5
JohnH cheers John, yes there is a Halfords in my town. Didn’t even know they sold multimeters. Il have a think Am I right in saying the fluke one doesn’t have a setting for amps ? If so is that an issue?
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Post by newey on Jan 26, 2020 21:42:47 GMT -5
No need. A guy named Ohm had a law that covered that. R = V/I, where R is the resistance, V is the voltage, and I is the current in amperes.
For guitar wiring, it's the resistance setting we will be using. There's not much reason to measure the voltage generated by your pickups (it's miniscule), other than just curiousity.
If, however, you start fiddling with the innards of amps like our Tragichero does, then the voltage settings will often be used. Don't try this at home, as they say, unless you first study the subject thoroughly, as Trage has done.
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Post by JohnH on Jan 26, 2020 22:33:38 GMT -5
Not a huge issue without an Amps scale IMO. The most useful ranges are Resistance, d.c. volts and a.c. volts. The Fluke has capacitance scales which can be handy but not essential.
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Post by ourclarioncall on Jan 27, 2020 7:22:24 GMT -5
Ok, great thanks for the info guys
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), and that you can attach small alligator clips to them. Many will be the times you wish to leave a lead attached to the same point for more than a moment, as you press the other lead to various points around the circuit. Alligator clips make this easy. Many test meters use the same input jacks for attaching the test leads, and wouldn't you know it, you can find and purchase test leads by themselves. You may wish to upgrade your test leads, who knows. (My Fluke leads are almost too long, they constantly get tangled and twisted around. 
)
According to the spec sheet, this thing is accurate plus or minus 1% + 60 counts over the entire frequency range from 20Hz to 100KHz - and this is at inputs of 1 mV! (The range and accuracy are reduced a bit, as the input voltage increases.) I'd have to go look, but I don't recall that my Fluke claims that resolution and accuracy. I don't think this guy is on the up and up, because if he's hitting the Peak button to get that voltage, only to whip out a calculator.... then why'd he buy such an expensive meter in the first place? 
