Electronic Design

Bob's Mailbox

Very good letter and comments about analog test equipment with knobs instead of pull-down menus (Electronic Design, Feb. 21, p. 133). Our company just bought a Tektronix TDS-3014 and I'm frustrated by the menu structure—But the thing is still incredible.

Anyway, I hate to bother you, but I'm at my wit's end trying to find a reasonable source of repair for my aging collection of oscilloscopes (453 and 454). I know one enterprising man who fills his retirement years restoring and rebuilding Simpson 260s (another fine analog instrument, my collection now numbers about 15), and selling them on eBay. He also has repaired some of mine at modest prices. I need someone like that to work on the old Tektronix 453 and 454 oscilloscopes in my very modest test-equipment collection. I don't need calibration certificates. I'm more interested in just having an operational unit. Do you know of anyone who may be able to help me?

In my TV/VCR shop days, I aligned many tape paths and troubleshot many video and audio circuits with a 453. But as your other readers said, finding repair people for the older equipment is becoming impossible. (If people who can repair them are hard to find—repair PARTS may be VERY hard to find. /rap)
MATTHEW JONES, Electrical Engineer
Kobelco America Inc.
via e-mail

Hello, Matthew. I'm sure that here in the SF Bay area, I could easily find people who do that. HALTEK in Mountain View has a lot of good old Tek equipment to sell, and the place next-door does too. But scopes are heavy. Largely, you want to know the people in YOUR area who can do it. You certainly wouldn't want to ship your scope a big distance, and then risk it getting rattled out of shape, or out of calibration, when it's sent back to you. So, you need to find a place near you. Where are you? I can't solve everybody's problems, but I can find a cure for yours. Best regards.—RAP

Dear Bob:
I just finished reading your latest "Bob's Mailbox" article on Knobs vs. Menus (Electronic Design, April 17, p. 127). This is a topic that has come up several times here at Fender. We could not agree more. I design vacuum-tube guitar amps, which was pretty difficult to learn about in school during the late '80s/early '90s. But tube guys still lurk in the basement corners of universities, even today. (Check. /rap)

I bought your troubleshooting book directly from you and you hand corrected it for me. Thank you. It's great.

We love your articles on speaker-wire hoaxes/frauds. Recently, we had a guy send us a high-zoot, braided wacky-skin-effect, directional, million-dollar guitar cable for evaluation. We plugged it into a high-gain guitar amp and it sounded like a rain-stick (an instrument which creates a sound like rain hitting a tin roof) anytime it was ever so slightly moved. Even our marketing people laughed at that. (Hilarious! /rap)

Another topic that comes up a lot here is analog vs. digital scopes. We have both, but I keep my 465B on my bench and the digital scope in storage. They each do their own things as well. (EXACTLY. /rap) For most stuff, though, I like the old knobs and switches on the 465 vs. the menus on the TDS320. (Check: Me, too. /rap) The 465's will show you things that the digital scopes seem to miss when sampling. The digital scopes are handy for storing transient events and their measurement utilities.

I agree that the difference between a low-distortion solid-state amp and a low-distortion tube amp is very difficult to hear, but the difference becomes much more apparent when the amp is designed to run into distortion, like in a guitar amp. (WELL, YEAH. /rap)

The reason that I can still get paid to design tube guitar amps is that most guitarists prefer the sound of tube distortion. Maybe it's because that sound was used to create all the original Rock 'n Roll albums that they love? (Let 'em roll. /rap)

I just think that a tube amplifier pushed into distortion sounds better. Someday you should stop by and listen for yourself. We make both kinds and they all sound good. We are in Scottsdale, Ariz., so try coming in the winter when it's not 120° here.

At the end of the Mailbox you wrote, "I know \\[knew\\] some of the guys who made analog electronic music instruments." I just thought you should know a guy who makes analog (tube even) musical instruments.
MIKE COZZA, Sr. Design Engineer
Fender Musical Instruments.
via e-mail

Thanks for the comments! If I had to listen to guitar sounds pushed through solid-state amplifiers and distorters, I might easily say, "That doesn't sound RIGHT." RIGHT is what we've been listening to for many years—and high fidelity doesn't necessarily have anything to do with it!—RAP

All for now. / Comments invited!
RAP / Robert A. Pease / Engineer
[email protected]–or:

Mail Stop D2597A
National Semiconductor
P.O. Box 58090
Santa Clara, CA 95052-8090

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