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Amp techs, what's on your bench?

#81
I have an R390A military radio on my desk for listening enjoyment. It also helps heat up the room.

I know a guy that had an old RCA shortwave radio in his shop. He never turned it off except for maintenance over a period of 40 years.
 
#82
Interceptor said:
One last thing a good shop has to have - a good radio.

Nothing to add to the joy of escaping to the shop like a football, basketball or even baseball game on a big fat tube AM radio. Or a 80 meter net in the winter months.

I gotta get a 80 meter antenna up while it is nice out.
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It would be great if there were any good AM stations around here. I'm a smooth jazz guy for listening while I work (which is funny because I really don't listen to that stuff any other time). So I usually either have on a CD, or if I am near a computer I have and internet station playing it. While I appreciate you "seasoned" guy sharing your wisdom with me, I probably won't go as old school as hooking up an 80 meter, or tube AM any time soon.

Now a ham is another matter.
 
#84
fdeck said:
One more thing... a paper notebook, unless you're really disciplined enough to record stuff on your computer.
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Man, I'm almost OCD. I'll probably do both. But my instructor really pounded this point the other day. Either working on the same item, or working on the same problem in another item will almost always come up. Good notes will save you time and aggravation on the back end for sure.
 
#88
This is speaker breakout box that I built. It allows you to daisy chain 1/4" and speakon cabs. I should probably have added a BNC connector as well.

The box is metal, the 1/4" jacks are isolated with switchcraft S1028 and S1029 washers, the speakon connectors have built in isolation. Everything is wired in parallel.


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#90
UncleFluffy said:
Especially when you're taking something apart for the first time. Pics are a big help when you've got to put it back together and there's two identical connectors that can go either way around.
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Sometimes I may not remember how I did something in the past. Keeping a record allows me to stop re-inverting the wheel. Just recently, I couldn't recall what make and value caps I used in an amp. The images allowed me to confirm exactly what was done.
 
#91
Oh yeah, with the noes, digital camera is always at hand, everything gets pictures before being disconnected. For immediate reminders, and it means if it doesn't work when I've put it back together I can troubleshoot from my pc. And have a record if someone decides to poke about themselves, and break it and say it was my work at fault (joy of ebay).
 
#92
For some reason, I never seem to have enough dummy loads. I'm in the process of building a new one with a pair of Invalid Link Removed resistors. These things are huge. I plan on mounting them on an aluminum plate inside a electrical panel box that will be on the wall. Cost kind of got out of hand, these resistors are expensive but I thought that I would give them a try. Below is some typical data for the Arcol NHS300, 8 ohm 1%.

Non-inductive resistors are nice to have for typical amp work but I don't think that they are necessary. There are some exceptions, but regular resistors don't have a very high inductance at low frequencies where tests are made. What do you think about non-inductive vs good quality regular resistors? If you want to make accurate power measurements and need to know the resistance for the calculation, I suppose non inductive is the way to go.


Anyway, here are some pics of an older one. The 200W, 8 ohm [Invalid or Expired Link Removed] are from Parts-Express. It is nice to have the 1/4" and speakon connectors. The banana connectors allow for different type of connections to the amp or instruments. I had concerns about heat being an issue with the resistors in a box but even with a 300W amp, they don't get too warm.



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#93
My workbench is all in parts atm. Actually, there's no bench right now. Once I've moved later this summer I'll have room again and can dive back in.

I have the usual compliment of hand tools, variable temp soldering irons, a 100W soldering gun for bigger stuff. I've got a decent DMM that measures all kinds of stuff. I've never killed it nor popped its fuse, and it doesn't seem to ever have given me a wrong reading, so I guess it's not crappy. I've even vaporized probes on it, accidentally (crappy radio shack rocker switch arced through them - I turned everything off and went outside for the rest of the day).

What I really want / need is a cheaper analog scope. I have no scope at all at the moment, and I've been eyeballing getting a variac and iso transformer once I've got space to work on stuff again. What's recommended by the more experienced guys that's affordable for us working stiffs?

This thread is awesome. I'm subbed.
 
#95
Worth mentioning is kid-proofing the work area, or at least, being very conscious about the hazards. Kids will reach out and grab things without thinking. And I don't want to exclude them from the fun stuff.

Oh, and one more idea. Soldering tips last a lot longer if you don't leave the iron turned on. I've got my iron on a timer that I picked up at Home Depot.
 
#96
I used to have a master power kill at work. It was a big red panic push button. If there's an emergency, everything goes off quickly. They sell similar switches for wood and metal shops.

Kid proofing is a good idea but they have a way of being a lot smarter than us when it comes to accomplishing the impossible.
 
#97
The best place to pick up used test equipment are amateur radio swap meets, or through word of mouth inside the amateur radio community.

An alternative is to watch the surplus sales sites that many of the major universities have. As an example: http://www.bussvc.wisc.edu/swap/

The things I'd be looking for in a used scope (other than that it works) is dual trace, probes included and that the display is plenty bright. The manufacturers of the sort of scope that would be ideal for a audio bench are B&K, Hitachi, Tektronix and Hewlett Packard. Virtually any scope on the market will have plenty of frequency response for audio work.

The older Tektronix and HP scopes pop up on the used market from time to time for almost free. Some even include a very nice wheeled cart.
 
#98
As far as non-inductive loads I have seen good results from good quality inductive resistors. I personally use the crossover notch method for bias and non-inductive provide a better adjustment. There was a "shop" where I used to live that built the load from toaster heating grids. Every amp they touched under-performed.
 
#99
Okay, since everybody's showing off their dummy loads, here's mine. I used 8 of the Parts Express 100 watters. They're wired so I can run them for stereo loads of 400 watts at 8 ohms per channel, or parallel for a single load of 800 watts at 4 ohms. Underneath them is a giant muffin fan, which you can't see in the picture. The meter is an ancient radio-frequency ammeter, or I can select to use an external ammeter. By hooking up the DMM, I can get voltage, multiply by amps, and get power in watts without resorting to digging out a calculator.
 

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#100
Interceptor said:
The best place to pick up used test equipment are amateur radio swap meets, or through word of mouth inside the amateur radio community.

An alternative is to watch the surplus sales sites that many of the major universities have. As an example: http://www.bussvc.wisc.edu/swap/

The things I'd be looking for in a used scope (other than that it works) is dual trace, probes included and that the display is plenty bright. The manufacturers of the sort of scope that would be ideal for a audio bench are B&K, Hitachi, Tektronix and Hewlett Packard. Virtually any scope on the market will have plenty of frequency response for audio work.

The older Tektronix and HP scopes pop up on the used market from time to time for almost free. Some even include a very nice wheeled cart.
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I'd go for that. I have a shed to put it in, too. I thought about building my own, but it seems to me that I'd almost need one to make one, and that sourcing some of the components might not be as simple as when Heathkit still sold them. And I just don't know squat about them.
 

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