need recommendation for tone generator to align tape machine

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gradwellhouse
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need recommendation for tone generator to align tape machine

Post by gradwellhouse » Wed Feb 28, 2007 10:38 pm

Hey guys,
I just got a Sony APR-24 24 track 2 inch and i need to buy a stanalone tone generator for it that can do 1k and 10k at +4db and 0db. XLR out or something that has an analog BNC out would be great but i can live without.

Steve

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ckeene
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Re: need recommendation for tone generator to align tape mac

Post by ckeene » Thu Mar 01, 2007 7:20 am

gradwellhouse wrote:Hey guys,
I just got a Sony APR-24 24 track 2 inch and i need to buy a stanalone tone generator for it that can do 1k and 10k at +4db and 0db. XLR out or something that has an analog BNC out would be great but i can live without.

Steve

http://gradwellhouse.com
Have you checked out the Neutrik Minirator? I have one and it's great for doing alignments and other diagnostics. It'll do sine/square/noise at a broad range of frequencies and dB outputs. It's also portable.

It was a little pricey ($200), but it's still a lot cheaper than a 2" calibration tape or head relap!

KFledman
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Post by KFledman » Thu Mar 01, 2007 7:41 am

i know it's not the perfect solution, but I use a CD with tones on it....I bought the Mix reference CD years ago and it has the necessary tones plus other stuff [20 minutes of SMPTE???? my favorite track...]
I just put the CD through a console and send the signal to the tape machine through the busses.......
Also, you may find that your console has a tone generator onboard...

gradwellhouse
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Post by gradwellhouse » Thu Mar 01, 2007 8:50 am

thanks guys....
I would run the tone from our board but.......no board.

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brianroth
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Post by brianroth » Thu Mar 01, 2007 9:08 am

In the mood for a DIY project?

Goto www.jameco.com and search for catalog number 20685.

http://www.jameco.com/Jameco/Products/ProdDS/20685.PDF

Downside...you stuff it into an enclosure with a power supply, and you have to measure/adjust the output level for +4 dBu.

Bri
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gradwellhouse
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Post by gradwellhouse » Thu Mar 01, 2007 9:48 am

FYI:
i just ordered one of the minirators, here is a link if you need one: http://www.proaudio.com/product_info.ph ... cts_id=658

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brianroth
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Post by brianroth » Fri Mar 02, 2007 2:19 am

The Minirator is a cool gizmo, but with limitations:

1. +6 dBu max output, useless for testing headroom.

2. Max 20 kHz sine wave frequency; you need at least 30 kHz to align a tape recorder at 30 IPS.

3. I prefer a 10 kHz square wave signal to "look at" a desk channel with a scope in order to detect any funny-biz.

At least it is (quasi??) balanced...

Bri
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Al_Huero
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Post by Al_Huero » Fri Mar 02, 2007 9:12 am

brianroth wrote:3. I prefer a 10 kHz square wave signal to "look at" a desk channel with a scope in order to detect any funny-biz.

Bri
This interests me. I've got an old Soundtracs board (16:8:16) that I want to go through. My idea was to send tones through each channel and hook the output up to a scope. Are there specific types of "funny biz" that would be indicative of failure of a specific component or is it really dependent on the channel circuit for the particular board. FWIW I have all the schematics for the board.

The Scum
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Post by The Scum » Fri Mar 02, 2007 11:49 am

There are a bunch of things that a signal generator and scope can tell you.

I usually use a 100 Hz or 1kHz square wave...in fact, many scopes have a 100 Hz 1V p-p square wave generator built in for calibrating the probes. It'll drive a high impedance line input nicely.

Because square waves contain a wide frequency spectrum, they're a very quick troubleshooting tool. The square wave will misbehave differently depending on what happens to it...and that can help you track down what might be wrong. Sine waves don't have much spectral content, so they aren't so useful at tracking down broadband phenomena.

You can pop in an EQ, and play with some cuts and boosts at different frequencies a hands-on demonstration of how things change.

If the tops and bottoms of the square wave tilt, the low frequencies are changing. They tilt one way for boosts and the other way for cuts. If you have older caps in the board, then this will very likely be happening, even before you play with the EQ.

If the rise/fall of the square wave overshoot the flat parts, then there's an HF boost somewhere.

If the rise/fall curve into the parts, there's HF loss.

Midrange cut/boost make the flat part of the square curve. This can make neato patterns on the scope.

If the trace gets really thick (make sure the beam focus on the scope is sharp first), then it could be noisy, or experiencing HF oscillation. Zoom in the timebase, and see of it ever resolves into a sine or triangle wave, often way up in the MHz range...if so, that's parobably parasitic oscillation of an unstable opamp. If it never resolves, it's probably just noise.

Al_Huero
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Post by Al_Huero » Fri Mar 02, 2007 2:17 pm

Good info, thanks!

getreel
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Post by getreel » Sun Mar 04, 2007 9:23 am

KFledman wrote:i know it's not the perfect solution, but I use a CD with tones on it....I bought the Mix reference CD years ago and it has the necessary tones plus other stuff [20 minutes of SMPTE???? my favorite track...]
I just put the CD through a console and send the signal to the tape machine through the busses.......
Also, you may find that your console has a tone generator onboard...
I use Sound Forge to generate tones on the DAW and then send them through the console buss outs to the tape machine. Seems to work fine but I'm not sure about the resolution and whether that makes any difference. Sound Forge will do sweeps any range and length you specify and other stuff like square waves as well. 16 bit 44.1 is what I'm using and that the same as your CD.

Everybody's X
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Post by Everybody's X » Sun Mar 04, 2007 10:27 am

wow that scope information is really useful thanks for the rundown

this may of may not be helpful, it is a test CD from Bink Audio

http://www.4horsemen.net/binkster/full_cd.zip

documentation available there as well
Dave Johnson
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