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Author Topic: Oscilloscope for RTR Alignment.  (Read 29141 times)

Offline john

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Oscilloscope for RTR Alignment.
« on: January 25, 2009, 03:26:49 AM »
I'm considering the purchase of an oscilloscope, what are the minimum requirements for tape machine use/alignment. Analogue or digital, frequency etc. below is the spec of one that I'm considering.

Scope Description

2 independent  floating channels

Max sensitivity vertical 5V per div

Min sensitivity 5mV per div 17.5nS rise time

25MHz with 100MS/S sample rate

Trigger Edge,Normal, Single, Auto, TV

Auto measurement of frequency, peak to peak voltage, true RMS voltage, average period.

Math add, subtract, multiply, divide, one channel by the other

Would this be suitable?
John Taylor

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Offline docb

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Re: Oscilloscope for RTR Alignment.
« Reply #1 on: January 25, 2009, 10:19:45 AM »
Hi John,

You want to be sure to get a scope that can do X-Y display, where one channel is sent into the horizontal and the other is sent to the vertical. This will allow you to generate the Lissajous figure that will help you nail the azimuth of the playback head.
« Last Edit: January 25, 2009, 06:16:54 PM by docb »
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Offline john

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Re: Oscilloscope for RTR Alignment.
« Reply #2 on: January 25, 2009, 11:26:36 AM »
Thanks Doc, I'll check that out.
John Taylor

Revox C270, Teac X-2000R, Technics RS1506, RS7500, Nakamichi Dragon, CR7E, Sony WM-D6C, Sony EL7 ( Elcaset! ) Brinkmann balance, Brinkmann Ti Cart, Clearaudio Balanced Ref, Esoteric XO1-D2, ARC Ref3, Ref 210, JM Lab Micro Utopia Be and Jas Audio Plato.

Offline microstrip

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Re: Oscilloscope for RTR Alignment.
« Reply #3 on: February 28, 2009, 01:24:02 PM »
Hi John,
If you have a good soundcard - I have Edirol UA25 - you can use the free software Soundcard Oscilloscope ( http://zeitnitz.de/Christian/Scope/Scope_en.html ) to align your machine. It has X-Y capability for Lissajous figures and an excellent signal generator with sweep options. It can also perform frequency analysis.
Francisco

Offline john

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Re: Oscilloscope for RTR Alignment.
« Reply #4 on: February 28, 2009, 01:58:06 PM »
Thanks Microstrip,
                        I will try that, it looks like it could be just the programme to use.
« Last Edit: March 01, 2009, 02:39:05 AM by john »
John Taylor

Revox C270, Teac X-2000R, Technics RS1506, RS7500, Nakamichi Dragon, CR7E, Sony WM-D6C, Sony EL7 ( Elcaset! ) Brinkmann balance, Brinkmann Ti Cart, Clearaudio Balanced Ref, Esoteric XO1-D2, ARC Ref3, Ref 210, JM Lab Micro Utopia Be and Jas Audio Plato.

Offline steveidosound

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Re: Oscilloscope for RTR Alignment.
« Reply #5 on: February 28, 2009, 03:22:39 PM »
2 considerations for scopes for troubleshooting R2R recorders.
These are not typically part of software scopes.
1. very high input sensitivity if one wants to look at the head output directly. Typically only a couple of millivolts.
2. DC blocking for high voltages - important if you go measuring around inside of a tube machine.

In addition, it is nice to have some sort of calibration so you can measure the level you are getting on the waveform as well as dual trace and X/Y lissajous patterns  for 2 channel comparisons.
Steve Williams

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Offline Ben

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Re: Oscilloscope for RTR Alignment.
« Reply #6 on: February 28, 2009, 07:50:20 PM »
Now the optional parts ... power cord and probes are often overlooked too.
Last time I looked, inexpensive probes can be found here.
http://www.oselectronics.com/index.htm
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Offline stellavox

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Re: Oscilloscope for RTR Alignment.
« Reply #7 on: March 13, 2009, 05:38:07 AM »
I suggest looking at the little Velleman battery powered scope - I have an earlier one, it works great and it's portability is a real plus

Charles

Offline ironbut

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Re: Oscilloscope for RTR Alignment.
« Reply #8 on: March 13, 2009, 12:23:59 PM »
Hey Charles, I was wondering about those little guys. Thanks.
Regarding software scopes, I use a program called Spectre which is $80 (for Mac). It's quite a bargain since it has tons of other meters. It's not the easiest thing to use but once you get the hang of it, it only locks up every once in a while (you have to hide it before you make any connection changes). That said, I think that if you foresee any need for doing any critical measurements (low level stuff like steveidosound was talking about) you're much better off biting the bullet and getting a real scope that you can have calibrated. A software scope (or measuring program) is only as good as the processor (analog to digital) that feeds it since the noise floor and the upper a lower frequency limits can be altered by the converters when going to digital. I think that for simply aligning your heads, you can do a reasonable job with one since you aren't going that high/low but once you get out of a set bandwidth or amplitude, you can't really trust them.
steve koto
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Offline miroslav

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Re: Oscilloscope for RTR Alignment.
« Reply #9 on: July 08, 2009, 01:32:24 PM »
Glad I stumbled on this thread.

I was just lining up to get a scope...but I think I will try out the software version first.
I have real good soundcards for my DAW that will do A/D/A at 24 bit up to 96 kHz...so no worries there.

With my couple of R2R decks...they've been babied and have seen only light to moderate use...so I was not too concerned that the heads had gone out of physical alignment...and they have no visible wear at this point.
That said...I figured it was time to put the decks up on a scope, especially my new Otari BIII which came by UPS, and they tend to bounce things!
I figure I can at least check the physical alignment...and if it comes up good...then I know my electronic calibration will be accurate.

I don't think I would have too much other use for a hardware scope...so maybe the software will be just the thing for me!


Offline docb

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Re: Oscilloscope for RTR Alignment.
« Reply #10 on: July 08, 2009, 02:29:02 PM »
Quote
(for Mac). It's quite a bargain since it has tons of other meters. It's not the easiest thing to use but once you get the hang of it, it only locks up every once in a while

What?! "Mac" and "locks up" in the same paragraph?! Tell me it ain't so. Only PCs have these problems. I know, 'cause a Mac guy told me so - while he was trying to figure out why he couldn't mirror his old Mac laptop HD onto his new Mac laptop.
Dan "Doc B." Schmalle
President for Life, Bottlehead Corp.
Managing Director - retired, The Tape Project

Offline ironbut

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Re: Oscilloscope for RTR Alignment.
« Reply #11 on: July 08, 2009, 03:48:37 PM »
Yeah yeah,..
Actually it's a little user error'ish. My tendency is to want to open up a whole bunch of cool looking meters all in one window so it looks kinda "Foo'ish". With this software it just doesn't fly. Also, if you open app's and switch routing while the meters are going,.. freezo!
They've been saying a new version is right around the corner but in the meantime, I'm just methodical in it's use.
Hey, what do want for $80?
steve koto
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Offline xcortes

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Re: Oscilloscope for RTR Alignment.
« Reply #12 on: July 08, 2009, 04:15:17 PM »
Hey Steve: I knew it was you
Xavier Cortes

Offline miroslav

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Re: Oscilloscope for RTR Alignment.
« Reply #13 on: July 08, 2009, 05:04:25 PM »

I have real good soundcards for my DAW that will do A/D/A at 24 bit up to 96 kHz...so no worries there.

I spoke too soon.

The software scope doens't work with 24 bit cards. :-(

I have an old 16bit card...not sure if I want to mess with my DAW just to install an old sound card because of the scope.

Offline stellavox

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"Software scopes" - BE CAREFUL!!!
« Reply #14 on: July 09, 2009, 05:39:08 AM »
I have nothing against software scopes but PLEASE keep in mind that you are using inputs and outputs to your soundcard that were "designed" to see signal levels from headphones/speakers and microphones.

You go using your PC as a piece of test equipment and you could inadvertently inject who-knows-what into it.  IF you do this please think about PROTECTING the I/O ports somehow.  I haven't done any research on this but someone probably has - like using back-to-back zeners from "hot to ground" to limit the voltages - and maybe even a micro fuse in series with the "hot" leads!  Hopefully there are I/O specs somewhere in your Soundcard literature - if not, ask.

Charles