Tube Amps / Music Electronics
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The sunn still shines online!
|2/16/2005 12:25 AM|
My old funky scope that I had forever finally died. I need to get another used one.
What are the top three contenders I should consider, for audio, tube amp work, ect? I don't want to spend alot.
|2/16/2005 7:10 AM|
Bob, I can't give you a top 3. Lord knows there were a zillion different brands made.
I can make some suggestions as to what to look for as far as features.
There are a lot of Ebay and hamfest specials out there you can get cheap, especially old tube models. Actually, you should check out any old tube 'scope you find - the last one I picked up had a couple of 12AX7's, a 12AT7 and a bunch of 6DJ8/ECCwhatever, all Mullards!
For audio pretty well anything with a 10 mhz or better bandwidth is more than good enough. The important thing is to have a calibrated input that goes down as sensitive as possible, like 10 or even 5 mv per division.
Lots of old Eico's just had a relative gain pot on the input, with no actual calibration. This means you can see if a wave is clipping but have no idea at what voltage this is happening.
Sometimes you can do a lot better. I picked up my last 'scope from a pawnshop for $135 Cdn, or about $110 U$. Two channel solid-state, 100 mhz and down to 10 mv. With probes, it was a steal! More 'scope than I'll ever need.
|2/16/2005 9:10 AM|
Thanks for your reply. What make/model o'scope do you use?
|2/16/2005 1:52 PM|
The brand is "Chiang", Bob! Obviously off-shore but nowadays except for high end lab equipment like Hewlett Packard I doubt if there are any domestic 'scope manufacturers left.
Works well, though and as I said it's far more 'scope than I need but the price was a steal.
|2/16/2005 2:17 PM|
I guess I wasn't so clear about what I'm asking.
What makes/models of oscilloscopes do the participants of this forum use? I would guess that we would use them in a mostly similiar fashion and our requirements would be somewhat similiar, as well. I'm looking for a used, inexpensive model, of course, in excellent condition to replace 'Ole Bessy' who had a quick demise after a long illustrious life.
|2/16/2005 6:19 PM|
I hate to admit it (sometimes), but I own more test equipment than God. I rotate what's on my bench every three months or so. It keeps my mind sharp, and that's no small feat. You cannot get into any habit or switch to auto-pilot with how your equipment works. Most everything I have I picked from old TV repair shops or the local Ham Radio Flea Market for pennies on the eBay dollar. If you want to save money, this is the way to do it.
What oscilloscope would I recommend? I don't know what Ole Bessy was, but if she was an old Heathkit like the 0-12, you can do way better. I have a couple of those, and they aren't very good for biasing. They work for troubleshooting, but that's it. Ditto for any similar siblings like Eico, Knight, Jackson. I just switched from a Telequipment D61a (10Meg) to a Leader LBO 508A (20Meg). I have all the way up to 100Meg (Hitachi V1065A), and the higher the bandwidth, the better it seems to work for things like biasing. For checking frequency response, or for square-wave tests, the higher bandwith is just better. If you want a middle-of-the-road oscilloscope, I'd suggest stay away from Tektronix, and not because they are bad oscilloscopes. They are wonderful oscilloscopes. But eBay makes them real expensive. If you can find one of the common 10Meg tube units, the'll work fine. But they're loaded with 6DJ8's, and eBay has priced those out of the reach of the common man. In 10Meg I also have a Philips PM3232 and the Philips PM3230. The PM3230 is also loaded with 6DJ8's, so the all FET PM3232 is more preferable to me. These should be cheap enough that you won't blow you budget. Keep watching eBay, and you may get a bargain. But not likely. Try the local TV repair shops first.
|2/16/2005 7:05 PM|
I'm partial to Tektronix scopes but hell, I used to work there. Most of the time I'm using a top of the line (70's and 80's) lab scope. Don't try one, they're addicting, but not too expensive to feed my habit. I keep the broken ones for parts. Ebay makes keeping them going a whole lot easier.
For audio use I have a T913 that I got at a flea market for $95 that's never given me a bit of trouble. I have a 465B that had a small problem when I got it. Fixed it for $0.59 without having the manual. The 2200 series is basically a T900 series in a different skin. I'd stay away from any of the old tube scopes, they're a nightmare or fix when they stop working. The weak points of any scope are the switches for horiz and vert scale and the high voltage supplys in high bandwidth scopes.
There may not be any analog scopes still made in the US. Most would be digital scopes with LCD displays (aka scope-meters). You can get boxes that hook up to PC's and even use a sound card in a pinch. The more bits the better.
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