Tinker with a Heathkit Distortion Meter IM-58 to test a Zenith 5R20 amp.

I use a Heathkit Distortion Meter IM-58 to check out an old Zenith Phono Amp 5R20. We look at how the meter works. We see how the distortion looks and sounds.

[@RestoreOldRadios]

Josh, this was my first seeing a distortion meter in action and I find your video informative and interesting. Thanks for taking time to pull this together. Best, Don

[@wa4aos]

Distortion is interesting with regard to what our ears like and don't like. A tube amp with 2 to 4% even harmonic distortion is usually found to sound rich or warm to our ears and is just one reason why tube amps are still so popular. However, an amp with a half of a percent ODD Harmonic distortion sounds very harsh to most of us.
So, when I play with tube designs, I don't concern myself with a percent or two of even har,pnmic distortion but I always try to keep odd harmonic distortion as low as possible.
If you do audio amp projects, any decent distortion meter is very helpful.
Good luck with your projects.

[@YouAllKnowBob]

Heathkit anything is fantastic. I used to buy the kits new back in the 70s and 80s. Now I look for cheap old ones to restore. They work fine and you can fix them yourself if it does break. Not like the new stuff that you chuck if it breaks. Nice demo! 👍👍

[@tinkeringwithelectronics]

Thanks Robert. Frankly, for my purposes, I can't see anything wrong with Heathkit stuff. And as you said, you have some of the best documentation for repairing it.

[@FluxCondenser]

Really interesting and timely for me as I’m currently building an Eico 378 audio signal generator from an unbuilt kit I purchased on eBay. I wasn’t familiar with your model of Heathkit generator until I saw this video, but it has the same interface as the Eico I’m building. I’m guessing the circuits are almost exactly the same. Like you, I didn’t really need an audio signal generator, but was more interested in building a 52 year old kit from an unopened box. It’s been a real treat so far and I hope to have it complete tomorrow or the next day. I imagine I’ll be experimenting with mine much as you are with an oscilloscope and some old amps. Take care, and great work on the video.

[@tinkeringwithelectronics]

I hope to see a video on your Eico. Even though already assembled, the Distortion meter was like new out of the box! Not a scratch or even any dust on the cabinet. Big contrast to the smoke stained amp!

[@Backtothefutureradios]

Thanks Josh! Great demonstration of using the meter. Im like you as far as what it was showing me, but its always fun to see the equipment that was used back before modern ewuipment! Enjoyed the trip to Dalton, I think you should make a video of how clean the insides of the heathkit was compared to the smokey amp!! Take Care--Larry

[@VintageElectronicsGeek]

I've been looking at DM's, great demo. Just an FYI, not all CRT DSO's and DSO's offer FFT, it's an extra addition, extra cost... ~Jack, VEG

[@tinkeringwithelectronics]

Thanks Jack. My knowledge on DSO's is limited to my Hantek. That's good information.