Newbie question - obtaining an oscilloscope

[ZBod]

I'm on the lookout for a used oscilloscope and am wondering
what you would agree would be the minimum requirements
necessary that I need to be looking for in one of these - in terms of bandwidth, sampling rate, and anything else I should be concerned about.

I don't anticipate using it for anything other than guitar
amps and possibly an old hi-fi amp in the future.

Thanks.

[stokes]

For most guitar amp use,anything that works would be fine.Dual trace is nice,and you can find them fairly cheap on ebay.Any bandwith etc. is fine for guitar amps.I have a 15mhz Tek.T922 I picked up for $50 on ebay,before that I used a 5mhz Eico tube unit from the '40's that was fine,but only had a single trace.For the most part you will use it to observe what is happening with your signal as far as distortion,the dual trace is nice so you can see the signal in 2 places in your circuit at the same time,for instance,you can watch the waveform on both sides of your PI at the same time,or you can see when the output starts to distort compared to any other place in the signal path.

[ZBod]

other equipment?

Thanks stokes. Will I need to buy a signal generator as well,
or does a scope provide it's own signal?

[nico.verduin]

The scope usually doen not provide for a signalgenerator. At most a 1kHz blockwave signal to trim the scope.

[stokes]

You will need an external signal generator of some kind.Most testing is done with a 1khz signal of about .25v or less.You can find plenty of audio generators on ebay that will give you more than you need,for as little as $10 or so.

[Mark Black]

A nice feature to look for on a signal generator is a "trigger" or "synch" output. Basically just an output that doesn't change amplitude with the variable output control.

You can feed that into the external trigger input on the scope to keep the waveform nice and stable while you play with stuff.

[Mars Amp Repair]

I would stay away from the older scopes out there....esp ones from the 70's or earlier.

My minimum requirement for a scope is 20MHz...sometimes you need to see oscillators & parasidic elements that are of a much higher range. On a 20MHz you can still see signals twice 20Mhz, albeit diminished in amplitude & with no guarantee of accuracy.

Also I consider dual trace pretty necessary. The ability to directly compare 2 signals simultaneously in an amp is very helpful at times.

I would suggest an integral gradicle for any serious tech. This only means that the grid lines are etched into the phosphors & not on a separate clear plastic sheet. Your display will be much more readable.

The rest is pretty much fluff. I have worked with specialized equipment that required things like delayed sweep & quad inputs, etc...but not necessary here.

good luck. glen

[bob p]

did you notice the existing thread on how to shop for scopes? the search function can be very helpful.

[bob p]

http://music-electronics-forum.com/s...ead.php?t=1856

[mlannoo]

thought this might help regarding your decision:

http://www.tone-lizard.com/Oscilloscopes.htm

[Bruce / Mission Amps]

I worked and fed my family for years in the mid 80's using and old boat anchor 500KHz HP scope from the ealry 50's. I only stopped using it because the new modern dual trace scopes started coming down in price where I could be a half way decent import job for around $400.00.
Now I stupidly have three dual trace 20Mhz and a Tektronics 100MHz... I could probably still get away with using the gronk 500KHz scope for about 95% of all the work I do with a scope.
Don't overbuy with a tool like this but when a good 20Mhz dual trace come by at a reasonable price... it's hard to pass up.