Test Equipment Anonymous (TEA) group therapy thread

[mnementh]

Completed re-cap of Fluke 8060A. Quick test to make sure all is well. Next step is full functional test and calibration.

*hands med his portable Widlarizer*

mnem
eebil little caps... eebil, eebil, eeebil...

[mansaxel]

...and people still pass around magical tales about what wood to make guitars from, the construction - both electronic and physical - of instrument amplifiers, how to (mis-)use microphones and so on.

"Smoke the tapes of your group!"

[mansaxel]

TE Observation: A Fluke C50 meter pouch fits the /80[0-9][0-9]/ series meters, nigh-on perfectly. Just received a pair of C50s from Hong Kong. One of course can question the authenticity. The fit and finish of these is impeccable and I will not bother more with the sourcing chain, but the packaging shows signs of New Old Stock, as if they'd hung in a retail store and were exposed to sunlight or similar. My 8060s now have a home, and I can have one in the tool case and feel good about it.

[mansaxel]

Unsurprising. When valves used to be in everything we were all aware that they can be microphonic but with modern unfamiliarity with the technology that 'obvious' fact has tended to be forgotten.

...and even then they wouldn't get up in the morning at Telefunken and say: "Oh, the weather is nice. Let's make some VF14 with low microphony today." When Neumann asked for a batch of VF14m, someone at Telefunken would just select them out of the normal production run.

And when, towards the end of the U47 era, the amount of rejects Neumann had to send back to Telefunken for being unworthy ("Delivery Check" was a thing back then) started rising, Neumann started to suspect foul play. A new step was added to the delivery check:

Code: [Select]

while new_valve {
    check_valve;
    if (check_result == OK) {
      release_to_manufacture;
      }
    else {
        check_for_white_dot;
        if(white_dot) {
           raise_alarm;
           reject;
        }
        paint_white_dot;
        reject;
}

The story tells that raise_alarm was called, a bit more often than comfortable.

Source: The Neumann coffee table book.

[med6753]

Full functional test completed. Calibrated and verified against two Fluke 8800A's and a Fluke 8600A.

Ready for work and project complete.

[nfmax]

...and people still pass around magical tales about what wood to make guitars from, the construction - both electronic and physical - of instrument amplifiers, how to (mis-)use microphones and so on.

"Smoke the tapes of your group!"

PJ Walker, founder of QUAD and inventor of both the full-range electrostatic loudspeaker and Current Dumping, was a flute player. He told me silver flutes always sounded better to play on, even though he didn't really believe it himself 

[AVGresponding]

...and people still pass around magical tales about what wood to make guitars from, the construction - both electronic and physical - of instrument amplifiers, how to (mis-)use microphones and so on.

"Smoke the tapes of your group!"

PJ Walker, founder of QUAD and inventor of both the full-range electrostatic loudspeaker and Current Dumping, was a flute player. He told me silver flutes always sounded better to play on, even though he didn't really believe it himself 

Nevertheless he may well be correct. Ignoring the obvious differences in resonances, harmonics etc due to the nature of the material the instrument is constructed of, and the dimensional variations, for any instrument that has any part in direct contact with any part of the human body, what it is made from will make a difference.
Different materials have a different feel, and especially for anything you put in your mouth to play, the taste will be different and affect the way it is played. The differences may well be small and/or subtle, but they will exist.
Denial of this is akin to audiophoolery; it is contradicted by what empirical evidence tells us.

[Cerebus]

And when, towards the end of the U47 era, the amount of rejects Neumann had to send back to Telefunken for being unworthy ("Delivery Check" was a thing back then) started rising, Neumann started to suspect foul play. A new step was added to the delivery check:

Code: [Select]

while new_valve {
    check_valve;
    if (check_result == OK) {
      release_to_manufacture;
      }
    else {
        check_for_white_dot;
        if(white_dot) {
           raise_alarm;
           reject;
        }
        paint_white_dot;
        reject;
}

The story tells that raise_alarm was called, a bit more often than comfortable.

Source: The Neumann coffee table book.

All the more reason to make sure that all your orders have a delivery address that begins "Inbound Inspection and Test Department" (even if you don't have such a department  ).

[Cerebus]

...and people still pass around magical tales about what wood to make guitars from, the construction - both electronic and physical - of instrument amplifiers, how to (mis-)use microphones and so on.

"Smoke the tapes of your group!"

PJ Walker, founder of QUAD and inventor of both the full-range electrostatic loudspeaker and Current Dumping, was a flute player. He told me silver flutes always sounded better to play on, even though he didn't really believe it himself 

Speaking as a former "fluter" I can attest that a flute with a silver or gold lip plate is much nicer to play. I don't think that the body material on a metal flute really makes any difference as long as the workmanship's good. A wooden flute however, needs a good dense wood to not sound 'hollow'. My flute teacher was actually also a goldsmith (member of the Worshipful Company of Goldsmiths, so rather more than a journeyman metal-basher) and despite the self interests involved also averred the same about precious metal flutes. He had had commissions to build solid gold and even platinum flutes so he could speak from experience.

[nfmax]

Nicer to play, though, or better sounding?

[Cerebus]

Nevertheless he may well be correct. Ignoring the obvious differences in resonances, harmonics etc due to the nature of the material the instrument is constructed of, and the dimensional variations, for any instrument that has any part in direct contact with any part of the human body, what it is made from will make a difference.
Different materials have a different feel, and especially for anything you put in your mouth to play, the taste will be different and affect the way it is played. The differences may well be small and/or subtle, but they will exist.
Denial of this is akin to audiophoolery; it is contradicted by what empirical evidence tells us.

Rule 1 of playing a flute: Don't put it in your mouth, in fact don't do anything with it that would allow you to taste it, or want to taste it.

[AVGresponding]

Nicer to play, though, or better sounding?

The two may be mutually inclusive. If you are comfortable playing an instrument, you are far more likely to produce a "good" sound.

[AVGresponding]

Nevertheless he may well be correct. Ignoring the obvious differences in resonances, harmonics etc due to the nature of the material the instrument is constructed of, and the dimensional variations, for any instrument that has any part in direct contact with any part of the human body, what it is made from will make a difference.
Different materials have a different feel, and especially for anything you put in your mouth to play, the taste will be different and affect the way it is played. The differences may well be small and/or subtle, but they will exist.
Denial of this is akin to audiophoolery; it is contradicted by what empirical evidence tells us.

Rule 1 of playing a flute: Don't put it in your mouth, in fact don't do anything with it that would allow you to taste it, or want to taste it.

Ok, the flute isn't the best example; I think I was thinking of the penny-whistle or whatever it's called. The point remains valid though, for any contact point with any part of the body, how it feels will affect how it is played.

[Cerebus]

Nicer to play, though, or better sounding?

Simply nicer to play. The feel of silver and gold on the underside of your lip is better. It slides over the skin more easily which means you get it in the right place more easily and it doesn't have a tendency to stick as you change your embouchure when moving between registers.

As a consequence it may be better sounding, but only because it makes it easier to get your embouchure, your technique, right - not as a consequence of any sonic properties of the material. The quality of sound coming out of a flute is 95% technique - my teacher could make my cheap crappy school flute sound sweet as you like, I could not.

[AVGresponding]

In my defence my own instrument is the guitar (heavy metal, sub genre thrash/death), and when I'm talking about a musician putting an instrument in their mouth, it's usually referring to the drummer chewing on the ends of his/her drumsticks...

[nfmax]

I got invited out to a concert of Nordic Jazz a couple of years back. My first thought was Won't the poles get in the way of playing their instruments?  But actually it was pretty good

[med6753]

What kind of flute does Ian Anderson play?

[Cerebus]

A standard "flute" as opposed to a wooden flute, an alto flute, etc. He's probably got a few flutes, just like guitarists rarely have one guitar. I know he started out with a Selmer student flute, which was even crappier than the Yamaha student flute I started out on.

Edit: Managed to find this: http://jethrotull.com/ian-andersons-flutes/ and it turns out that Ian has used a huge selection of, mostly low end nickel-silver*, flutes.

*Also known as German Silver. Most people have some of this in their pockets with someone's head stamped on it.

[capt bullshot]

What kind of flute does Ian Anderson play?

In German: "Querflöte" (dict.leo.org tranlsates this to "transverse flute")

[mnementh]

"EEEEK!!! e's got spoiderzz in 'izz hair!!!"   ~ Mum usedta say of Ian Anderson

mnem

[McBryce]

Full functional test completed. Calibrated and verified against two Fluke 8800A's and a Fluke 8600A.

Ready for work and project complete.

May it serve you long and well!

McBryce.

[capt bullshot]

Not particularly TEA, but YaVLt (yet another victim of leak tubes):

[mnementh]

For my fellow nerds who haven't seen it yet.

mnem

[ch_scr]

It's Friday evening, time for some Fun with TE!

Todays star of the show: a low noise preamplifier
It's set to a gain of 1000 and limits the bandwith from 1Hz to 30kHz. We see the output on the scope and dmm.
I'll adjust the timebase to show the noise best I can but leave the sensitivity the same.
Please excuse the shoddy camera work, still fighting with it a bit. Also, sorry for the big pictures Vince.

First let's check a LM399 based voltage reference:

Typical datasheet noise is 7µV, maxium 20µV in a bandwidth up to 10kHZ. We measure 33µV, but the circuit itself has some gain, the bandwidth is up to 30kHz and these are actually Czechoslovakian-made MAB399 clones - it's in the ballpark I'd say.

Next up, a reference based on a zener running at 5mA.

If it weren't for some kind of evil wiggle it would be lower noise as expected for the higher current.
I'll have to come back to this and see where that comes from 

Number three is a low noise voltage regulator based on https://wenzel.com/documents/finesse.html

Now that looks more like it!

Nice and well you might say, but how noisy is the supply you are powering this with?

Not exactly low noise, a linear supply based on LM723.

Now, what about that switching supply lurking below?

It's a switcher alright  But still only 2.5 times the noise of the linear one so not too shabby (it is without load though)

[Neper]

Not particularly TEA, but YaVLt (yet another victim of leak tubes):

Please remove batteries when not in use...

Or as we say in German: Wer nicht hören will, muss fühlen (Who doesn't want to listen will be forced to feel).