Test Equipment Anonymous (TEA) group therapy thread

[Specmaster]

It rained and stayed above freezing here last night so the outside hose would be thawed. Took advantage of that and cleaned the 2 scope carts. "Simple Green" cleaner, scrubbed with a brush, and hosed down. IMHO they still look like crap but compared to when I started it's like night and day. They really need a complete teardown. Polish the chrome and repaint. But I'm not investing in that time and effort.

The sun will come out later and dry them out.

If you're still going to flip them, it might actually pay off to go the extra mile and paint them, polish the chrome etc, and then you'll command a better price for them? Or is the world of Tek like the car market, where sometimes the originality is king?

[mnementh]

So is it not true that what ever method of stereo reproduction is employed / size of enclosure etc, it is never going to be perfect?

In well over 99 precent of all listening situations two  four sixteen decent speakers judiciously positioned will do nicely.

FTFY. 

mnem
QUADROPHENIA, yo. They built a whole new recording studio chasing the Quadrophonic sound unicorn, and their tours were all Quadrophonic staging. And Dark Side of the Moon & pretty much every Floyd/Waters tour afterwards, too.

[med6753]

If you're still going to flip them, it might actually pay off to go the extra mile and paint them, polish the chrome etc, and then you'll command a better price for them?

The time and effort to do that compared to the potential ROI is not worth it to me.

[mnementh]

I was looking at the wrong databook.  The NS chips I have are marked  DM8577   DM74188.    Went back and found it in the 1976 TTL handbook.

The 8577 was a proprietary part that is pin-compatible with the 74188.     Vpp is 20-22V  applied to the output.   

Oh, sweet cheese and crackers. 

You mean at this point, the programmers for these "seminal design" chips are lost to history, and you'll pretty much have to build one from scratch...?

This is looking to becoming a very deep rabbit-hole, brother. Moar powah tooya!!!

mnem

We'll be waiting for you on the other side. With milk and cookies.

[mnementh]

...Also, of course, people's perception of sound quality varies enormously, SWMBO for instance is perfectly happy listening to her favourite, band Westlife, on the crappy little speakers built into her iPad and will not listen to either the CD player in the lounge with proper speakers distanced nicely, nor the BT speaker system and yet she goes to their live concerts almost annually, WTF!!

I think there is a lot of difference in how people appreciate music; it seems in my experience there are two fundamental approaches: Reliving vs Remembering.

The Reliving approach is the Home Theater/Concert Hall/Listening Room approach and revolves as much, if not more so, around the satisfaction derived from reproducing the original experience as closely as possible as it is the feeling of the original experience itself.

The Remembering approach usually is the headphones/handy speaker/whatever player happens to be at hand approach; it revolves entirely around reminding oneself in the moment at hand of the feelings one had at the original experience, and requires much less visceral reproduction of the sound, as the experience is almost entirely in one's head.

I'll let all y'all decide for yourself which aspect is most relevant in your own case; though most of us nerds generally tend more towards the "visceral reproduction" approach in both audio and video than the "listening with the mind's ear/seeing with the mind's eye" approach.

There is of course another alternative POV, which says that the sound mixer/recording engineer listens to all of it through headphones while s/he is making the master; so why shouldn't we listen to it that way...?

mnem

[Andrew_Debbie]

I was looking at the wrong databook.  The NS chips I have are marked  DM8577   DM74188.    Went back and found it in the 1976 TTL handbook.

The 8577 was a proprietary part that is pin-compatible with the 74188.     Vpp is 20-22V  applied to the output.   

Oh, sweet cheese and crackers. 

You mean at this point, the programmers for these "seminal design" chips are lost to history, and you'll pretty much have to build one from scratch...?

This is looking to becoming a very deep rabbit-hole, brother. Moar powah tooya!!!

mnem

We'll be waiting for you on the other side. With milk and cookies.

 If there are any commercial programmers left, they are buried in someone's garage.   

I'm planning to build one.  I was getting close to putting parts into a breadboard when I realized the NS chips I have are entirely different to the TI ones.

I'm in so deep I might as well keep on digging.

[Andrew_Debbie]

I think there is a lot of differwnce in how people appreciate music; it seems in my experience there are two fundamental approaches
mnem

I listen with a pair of well used, repaired many times  Sennheiser  HD 580  / 600s.    Drive them with either my home made DAC and amplifier or  a  cheap KGUSS DAC/amp combo I bought on AE.     Sound is very good but not audiophile.   The cost of anything substantially better appends a couple of zeros to the price.

I'm sort of in the middle of building an audiophile headphone amplifier.  I've got about $250 in parts in the power supply. The PS is complete and working.  I don't think I'll ever build the rest.

[TERRA Operative]

The TDS620B scope turned up today, all powers up ok, very slight burn-in on the screen, but not noticeable at all during use, so meh.

Seems it has a Cal Initialization error that doesn't go away with the usual tricks (I knew when I bought it).
So, time to buy some relays for the hybrid acquisition modules and cross my fingers that's all it needs.

No interesting options in this unit to pilfer, so once the fault is repaired it'll get a feature unlock and sold off for a good profit to buy the next bit of gear.

[Neper]

There is of course another alternative POV, which says that the sound mixer/recording engineer listens to all of it through headphones while s/he is making the master; so why shouldn't we listen to it that way...?

I've met a bunch of sound engineer colleagues in my time with various radio stations, recording studios and a national radio broadcaster, but I've never met a single one who'd do his mixing, mastering or recording using headphones. With two obvious exceptions: binaural (artificial head) recording and mobile set-ups where loudspeaker monitoring wasn't possible. Everything else was and still is done using loudspeakers.

[mnementh]

Yeah, at one time I chased the quadro unicorn myself, only with headphones. Built some FR4 panels to fit in a pair of old Sony deep-cup monitor headphones holding dual 40mm TDK drivers with a 50mm TDK driver behind, all powered directly by a stack of AT phonograph preamps fed from active crossovers which I constantly experimented with. Never could get the amplifier hiss processed down to a tolerable level; no matter what the quadrophonic source, it just managed to punch through the crossovers and overpower the music portion of the signal.

In hindsight, that was probably a matter of impedance mismatch as any failure in the component bits... I got soooo clooooose so many times... with different amps and crossovers... but never got it quite right. I gave up halfway through scratch-building a 6-ch DBX-certifiable amplifier for them.

mnem
*certifiable-dwagon*

[mnementh]

There is of course another alternative POV, which says that the sound mixer/recording engineer listens to all of it through headphones while s/he is making the master; so why shouldn't we listen to it that way...?

I've met a bunch of sound engineer colleagues in my time with various radio stations, recording studios and a national radio broadcaster, but I've never met a single one who'd do his mixing, mastering or recording using headphones. With two obvious exceptions: binaural (artificial head) recording and mobile set-ups where loudspeaker monitoring wasn't possible. Everything else was and still is done using loudspeakers.

No idea. I've never actually been in a position to know directly; just passing on what was at one time (maybe no longer...?) a popular argument for listening via headphones.

I've owned a number of "studio monitor" speakers in my time; I assumed they were primarily used as "reality check" playback devices or as monitors for the artists to hear themselves...?


mnem
 

[Vince]

Ebay auction for that Tek 576 curve tracer someone posted on here recently, has ended :

https://www.ebay.de/itm/224697429564

Made "only" 680 Euros, that is a third or quarter of what the usually go for... now only time will tell us if that was just good luck, or if it's more structural and the 576/577 "Bubble" is finally deflating ?! Will see....
No, I don't want one anyway.. much prefer my retro 575 

[Neper]

I got soooo clooooose so many times... with different amps and crossovers... but never got it quite right.

I've tried a number of so-called quadro or surround headphones using individual transducers for the four (or whatever number of) channels and the verdict couldn't be simpler: they all don't work. Period. There are still some of them sold to computer gamers but all serious manufacturers like Beyer or Sennheiser have given up on them years ago.

The only thing that does work to some extent is HRTF, i.e. processing the signal into a binaural format and then listening through conventional stereo headphones. I'm still using this one:

https://global.beyerdynamic.com/catalog/product/view/id/40/s/headzone-pro-xt/

[TERRA Operative]

Ebay auction for that Tek 576 curve tracer someone posted on here recently, has ended :

https://www.ebay.de/itm/224697429564

Made "only" 680 Euros, that is a third or quarter of what the usually go for... now only time will tell us if that was just good luck, or if it's more structural and the 576/577 "Bubble" is finally deflating ?! Will see....
No, I don't want one anyway.. much prefer my retro 575 

I should fix my 577 one day. So far I know there are some shorted tants, and the usual power supply electrolytics need attention too.

[mansaxel]

That is the very same model of device we used to measure the integrity of the earth mat at 6WF/WN MF transmitter site  back in the day.

Cool! I sort of imagined that as an outlier application, and something like it may well be something I'd try using it for. Seller has callsign, so that might be what he used it for.

[SoundTech-LG]

Did Tek make a dedicated cart for the 575? I'm using one that held my 555, and looks just like the pair Med has. Works perfectly.

[Vince]

I don't know why they would, the 575 has similar cabinet dimensions to any other Tek scope of that era.. no need to make a special cart for it....

[mnementh]

I got soooo clooooose so many times... with different amps and crossovers... but never got it quite right.

I've tried a number of so-called quadro or surround headphones using individual transducers for the four (or whatever number of) channels and the verdict couldn't be simpler: they all don't work. Period. There are still some of them sold to computer gamers but all serious manufacturers like Beyer or Sennheiser have given up on them years ago.

The only thing that does work to some extent is HRTF, i.e. processing the signal into a binaural format and then listening through conventional stereo headphones. I'm still using this one:

https://global.beyerdynamic.com/catalog/product/view/id/40/s/headzone-pro-xt/

LOL... yeah, the discrete driver setup for 5.1 sound actually works in a gaming application, because the games are produced in 5.1 sound, the sound card is designed around 5.1 sound, the frequency response is relatively narrow, and the standards for "acceptable artifacting" are generally pretty low in this scenario.

Sortof the same way a general-purpose computer monitor makes a lousy TV, and making a computer monitor that displays moving images well takes a lot of work and burns a lot of horsepower/bandwidth.

mnem
 

[mansaxel]

Found one instrument at the back of the garage that I had forgotten about. A Wavetek 191 20 MHz pulse / Function generator. Good all round instrument if you don't need digital setting accuracy.
This will be coming back into the workshop

I know that beast! When I last used it at a company from the United Technologies conglomerate, I noticed that a significant percentage of engineers are totally lacking understanding of what pulse generators can do for them. Maybe it is the naming. Using it as a pulse delay simply doesn't occur to them.
I used it in conjunction with a fast thyristor to make a short appear precisely where I wanted it - current or voltage maximum.

Funnily enough the first ask I have for it is similar. I need to produce short DC power interrupts. This is to test hold up during source switchover. The 191 is ideal. Lots of voltage to drive a MOSFET, isolated output and a manual trigger button.

One of the things I'm contemplating building One Of These Days (tm) is a 1KHz sine oscillator, Wien bridge, on Euro-style PCB; I've got a card frame that I'm going to put a variety of cards in. No sound system is complete without a tone. I also want it to be stereo, so I'm thinking of interrupting left channel out for perhaps 0,1 - 0,3 ms once every 2 sec. Not that your application is the same, but testing the muting circuit would be quite similar.

The pulse gen on the card is likely going to be a 555 one, with peripheral components selected for a short duty cycle; driving a transistor muting circuit. And then balanced drivers made from TL 072s.

[mansaxel]

So is it not true that what ever method of stereo reproduction is employed / size of enclosure etc, it is never going to be perfect?

In well over 99 precent of all listening situations two decent speakers judiciously positioned will do nicely.

And even more so if there were but two microphones involved in capturing the recording. Or perhaps three -- the Living Stereo recordings come to mind.

[mnementh]

I think there is a lot of difference in how people appreciate music; it seems in my experience there are two fundamental approaches...   

I listen with a pair of well used, repaired many times  Sennheiser  HD 580  / 600s.    Drive them with either my home made DAC and amplifier or  a  cheap KGUSS DAC/amp combo I bought on AE.     Sound is very good but not audiophile.   The cost of anything substantially better appends a couple of zeros to the price.

This pinged on my RADAR a week or two ago after watching a Linus video:

https://drop.com/buy/massdrop-x-sennheiser-hd-58x-jubilee-headphones

Honestly seemed a little too good to be true at that price. Any opinions...?

mnem
 

[mansaxel]

They would have made moving even more hellish

...but probably a lot faster than with a simple infernal combustion engine. 

I've offered Middle Boy the choice of Father-Son activity;

• Crewing and maintaining a Decauville museum railway
• Same, but on a 1970s torpedo/missile boat, powered by three R&R gas turbines

We've recently been out on a short ride on the missile boat and it does upward of 40 knots. Fast moving.

[Neper]

• Crewing and maintaining a Decauville museum railway
• Same, but on a 1970s torpedo/missile boat, powered by three R&R gas turbines

Guess I'd go for the Decauville railway.



I'm old enough to have known and used the marvellous Hovercraft ferries between Boulogne/Calais and Dover with their four RR engines. Never been topped so far. 

[Saskia]

Hmmmm... anybody here know anything about cost of living in Hartford, Connecticut...?

From what I can remember from my visit to the Danbury area in Ct (which is where our main US office resides) prices were high. Mind you, it is still in the vicinity of NYC even tho that one had done a dive.

You don't want to know about anything nearer to NYC like White Sands or Mamaroneck. Mamaroneck: 3 bedroom acceptable house in decent condition was 850k about 15 yrs ago. There was a good Sushi place in Mamaroneck back then. However my (ex-) buddy Mike, a scottish highlander, cut off all ties when I told him I would be marrying Hubby with the words "I won't be bothering you".
FFS, he's married with 3 kids. I did not want to mess up his marriage (even though his wife said that I should not be flirting that obviously ...)

I did not understand his reaction back then and I don't understand it even after 15 years ...   He had a few strange addictions as well, he was collecting gas turbines ...

You should know better than to flirt with a married woman.

What we're finding is that there appears to be a decent balance of pay scale for teachers vs cost of living right now, combined with one of the best student:teacher ratios in the country, plus for me a IT boom similar to Toronto at about 3/4 the cost of living. That is, if half of what we've been able to research so far is true. 

mnem

I did flirt with him in her presence and she told him to tell me that I needed to not make it that obvious.

[Cerebus]

What's wrong with collecting gas turbines 

nothing. I am arse-biting myself that I did not trade $someofmystuff for $oneofhisturbines ...

They would have made moving even more hellish 

Either that or considerably faster.

"NOTAM: Saksia is moving on ..."