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[JGreenslade]

In concurrence with what's been said already, I can only reiterate that a 'scope is probably the most useful tool a studio will ever own.

Aside from aligning tape-decks, the general-purpose applications for a 'scope are endless; OTOH: checking channel separation, checking wiring phase of patchbays / wall-boxes / transformer-isolation boxes etc etc, looking for distortion by comparing the input waveform to the output (you need a dual-trace unit, but most units tend to be), setting-up phono cartridges etc etc etc.

I should also add that 20MHz will suffice for audio - going above 20M isn't likely to tell you much...

A true-rms meter, a 'scope and an oscillator should be all you need to debug the average studio. With a touch of diligence, you should be able to find all 3 for less than the price of a couple of new 2" tapes...money well spent.

Justin

[acorec]

electrical wrote on Sun, 11 December 2005 15:59

Greg Norman wrote on Sun, 11 December 2005 15:48 Eng.Hamza Al-Shokani wrote on Sun, 11 December 2005 14:05 where do we find the procedure to do tape deck alignment? I would like to know why? thanks. Your manual. Greg's just being a dick. I don't encourage that. The oscilloscope shows a trace of a waveform, voltage over time. When playing back a test tape, you'll see the familiar trace of a sine wave. Using a dual oscilloscope, you can look at two tracks, one on the top of the headstack and one on the bottom. You adjust the azimuth on the playback head until the two waveforms are synchronized or superimposed. This implies that the head is then perfectly perpendicular to the direction of the tape travel.

DO you prefer an analog or digital o-scope?

[bobkatz]

dcollins wrote on Sun, 11 December 2005 14:29

Bill B wrote on Sun, 11 December 2005 10:01 And possibly a bit meter? LOL! DC

To measure the bit depth of GP9 versus 456, right?

BK

[jfrigo]

bobkatz wrote on Mon, 12 December 2005 09:12

dcollins wrote on Sun, 11 December 2005 14:29 Bill B wrote on Sun, 11 December 2005 10:01 And possibly a bit meter? LOL! DC To measure the bit depth of GP9 versus 456, right? BK

Nah, cause you can meter a bit of this, and a bit of that...  

But seriously, I have one around for all the same reasons that Steve mentioned, plus it's actually good to refer to when explaining certain things to clients. It's usually set up for lissajous display (XY mode on a dual trace). On the SSL G+ the built in meter has lissajous display so it just gets left on that as the option spectrum mode is pretty useless. In the mastering studio we just have a typical old B+K set up. Even if you don't look at it too often outside of alignmet, it's nice to have around for the occasional glimpse.

[cdr-1]

I've been looking for an oscilloscope since I got my first set of MCI JH-110's a few months ago.

Any tips for somebody looking to pick up their first oscilloscope? That is to say, what am I looking for in a good oscilloscope, what makes for a shit oscilloscope?

What about oscilloscope calabration? How tough is that? What equiptment do I need to do it?

nice emoticons on this board.                            

[Gold]

I picked up the first scope I really love a few months back. An HP1200B it's the rackmount version of the 1200A. It's an old analog scope that has a low bandwidth(500kHz) and has a high sensitivity for seeing very low level stuff. The trace is crystal clear. They're cheap.

[JGreenslade]

This is a selection of the typical kind of ‘scopes that you may see in studios, turned up by a 5min Ebay search (note: the links illustrate typical model numbers / specs – I am NOT advising you to buy these very items):

   http://cgi.ebay.com/Hitachi-Oscilloscope-V-202F-20-MHZ_W0QQi temZ7570619337QQcategoryZ104247QQrdZ1QQcmdZViewItem

   http://cgi.ebay.com/Hitachi-V152F-15MHz-Dual-Trace-Oscillosc    ope_W0QQitemZ7569839697QQcategoryZ104247QQrdZ1QQcmdZViewItem

   http://cgi.ebay.com/Hitachi-V-212-20mhz-Oscilloscope-NR_W0QQ itemZ7571000487QQcategoryZ104247QQrdZ1QQcmdZViewItem

   http://cgi.ebay.com/Kenwood-CS2075-70-MhZ-Oscilloscope_W0QQi temZ7570773063QQcategoryZ3319QQrdZ1QQcmdZViewItem

   http://cgi.ebay.com/Tektronix-465M-Dual-Trace-100-MHz-Oscill    oscope_W0QQitemZ7570886161QQcategoryZ104247QQrdZ1QQcmdZViewI tem


   http://cgi.ebay.com/Tektronix-465M-Oscilloscope-100MHz-2-Cha    nnels_W0QQitemZ7572089280QQcategoryZ104247QQrdZ1QQcmdZViewIt em  (This one looks particularly cool btw)

   http://cgi.ebay.com/Tektronix-465M-100-MHz-2ch-Oscilloscope_ W0QQitemZ7570807391QQcategoryZ104247QQrdZ1QQcmdZViewItem

   http://cgi.ebay.com/Kenwood-CS5140-2-Channel-40-MHz-Oscillos    cope_W0QQitemZ7570399892QQcategoryZ104247QQrdZ1QQcmdZViewIte m

   http://cgi.ebay.com/Tektronix-2225-50MHz-Oscilloscope_W0QQit emZ7571130858QQcategoryZ104247QQrdZ1QQcmdZViewItem

   http://cgi.ebay.com/Tektronix-2205-Oscilloscope_W0QQitemZ757 1055110QQcategoryZ104247QQrdZ1QQcmdZViewItem

More advanced ‘scopes may offer RMS voltage / frequency etc, and these features may be handy, although a decent modern multi-meter can offer these features.

As Paul asserts - you don’t need oodles of bandwidth for audio use – 20MHz is enough.

I can think of professional designers who use cheap ‘scopes.

Digital ‘scopes don’t offer an advantage unless you want storage (how often will you need that?), or work on digital gear often. If you do a lot of DIY / design then I guess storage could be handy...it’s easier to display / compare screen-shots. You can get analogue ‘scopes with storage btw.

Calibration is easy, as long as you have the manual... If it's an industry-std 'scope such as a Tek, finding a manual won't be an issue.

Hope this helps!

Justin

BTW, in terms of value-for-money, I rate Japanese units such as Hitachi and Kenwood highly – they tend to be reliable, and the front-end electronics are relatively quiet.

[timrob]

IIRC, some of the Kenwoods also have a tone generator that outputs 1k or 1.5k at mic level. Very Useful for testing Mic pres.

Look around on eBay as suggested or find a Ham Radio operator and ask him when the next Hamfest is taking place. You can get scopes fairly cheap. Even an old Heathkit would do the trick.

[boogalaboogala]

I've got a stupid question:  How would I connect a scope to my rig (Digi002R)?  How do I get from standard outputs (xlr, trs, etc...) to BNCs to go into the scope?  I'm sure the answer is obvious.

Thanks.

[JGreenslade]

You want a set of 'scope probes that are in good condition btw; ideally each side of the pair (for a twin-trace unit) should be matched (you calibrate the probes as part of the procedure described in the manual).

You have 2 options for latching the probes to your XLR: either remove the lid of the unit you're testing and latch probe to pins on the inside, or use a blank XLR plug with the terminals exposed and hook the probe on that way.

Getting a 'scope for the first time can *seem* daunting, but it shouldn't be. Even if you're not up on the theory of operation, you can twist the controls until it shows a waveform that makes sense - after a period of doing this you'll appreciate what the controls do - rocket-science it ain't (although understanding higher functions will take some study, basic waveform monitoring can be done by anyone).

The XYZ of 'scopes (I would suggest printing it off and studying when you have time): http://www.testmart.com/webdata/appnote/1603.PDF


Justin

[Gold]

boogalaboogala wrote on Tue, 13 December 2005 18:02

I've got a stupid question:  How would I connect a scope to my rig (Digi002R)?  How do I get from standard outputs (xlr, trs, etc...) to BNCs to go into the scope?  I'm sure the answer is obvious.

Interfacing unbalanced and balanced lines isn't obvious. Some things will work most of the time but not all the time. Vague enough for you? Every solution has it's pitfalls and also depends on the source circuit.

Another feature of the HP1200A is that it has a floating balanced input. Very handy.

[JGreenslade]

A salient point there Paul.

Unless you have a balanced input on the 'scope, you'll need to know what kind of output-stage you're dealing with...

This is a field where one shouldn't generalise, but as a starter (and to save me RSI):

The vast majority of modern units these days use "electronically balanced" outputs, via an "op-amp" or buffer of sorts (be it discrete / fully differential / ic-based dual op-amp); in this case you can tap into either the hot or cold leg and look at the signal (if your 'scope isn't balanced), although it'll be 6dB lower (half the voltage). Remember each leg is at 180degrees from one-another (states obvious).

If you have a "cross coupled" o/p, you need to ground the cold leg - I don't see CC o/ps too often, so maybe someone else can chime in if I'm missing something (see link below).

Transformer outs: Use the cold leg as ground, leave the connector ground floating (unless you have a particular reason, in which case connect cold to the ground).

The most tricky part here's going to be figuring out what technique your unit implements... You'll usually know if it's transformer...but confusion can reign when it comes to discerning cross-coupled from a dual / inverting op-amp.

Remember NOT to ground the unused leg in "electronically-balanced" o/ps; ONLY ground the cold leg in active o/p-stages in a Cross-Coupled situation.

This link provides more info: http://www.rane.com/note124.html

http://www.rane.com/note110.html

Justin

[electrical]

thermionic wrote on Wed, 14 December 2005 07:08

You want a set of 'scope probes that are in good condition btw; ideally each side of the pair (for a twin-trace unit) should be matched (you calibrate the probes as part of the procedure described in the manual). You have 2 options for latching the probes to your XLR: either remove the lid of the unit you're testing and latch probe to pins on the inside, or use a blank XLR plug with the terminals exposed and hook the probe on that way.

We have wired the scope inputs into our patch bay, which works well with floating inputs, as it allows you to patch it into anything and ignore the special grounding considerations outlined above.

[boogalaboogala]

Now that's using your nugget.  Thanks, Steve

(...and Paul and Justin).

[JGreenslade]

For absolute clarity I should add - in concurrence with Paul and Steve - that a 'scope with a balanced input will make life easier for studio purposes.

My suggestions in the previous post were based on common 'scopes you see for sale that are suitable for bench and studio use. If the 'scope is going to live exclusively in the studio, it may well be worth the bother to find a unit such as Paul's with balanced inputs for convenience's sake.


Justin