New Vintage Audio Restoration HQ

[Michaels HiFi]

I didn't realize it at the time - but the series of videos I produced on experimenting with digital audio & tweaks when my channel was just starting helped launch it.

The premise was simple: rather than deal with the forum nitwits arguing endlessly on topics they'd never actually tried themselves (in this case digital audio), I bought 16 network switches with my own money off Amazon and spent 60+ hours experimenting and reporting on my findings. Yes - I decided to actually TRY vs. simply arguing on a topic I had no experience with. Surprisingly a simple yet novel idea for many.

I found it incredibly interesting with what I learned about network switches, vibration control, digital cables, and more and has allowed me to get fantastic sound from the gear I have by maximizing their potential.

This has consistently provided traffic on my page of over 1 million views per month of people interested in the road less traveled: boutique tube amps, audiophile tweaks, and vintage tube exploration.

It's amazing for topics that receive so little attention from the main stream "pay for play" media and corrupt audio forum owners (present forum excluded), there is such an interest in these topics.

The recipe is simple: talk about topics that interest me from the heart and share the passion I feel towards them, while ignore the boring main stream gear and topics. I make content for the pure fun of it that I find interesting, and if others do as well and want come along for the journey, that's great.

And I'm adding a new passion: learning through trial and error the restoration of vintage audio gear.

That's right - I admit I am learning wood working, wood restoration techniques, and teaching myself how to repair vintage electronics through joining local clubs.

So if you have electrical or restoration tips and techniques, I'd love any tips you can share along the way. For others, I hope you'll find as interesting as I do the attempted restoration of audio from the Golden Age.

 

[atmasphere]

What is the Golden Age?
I recently restored this bit of audio history (late 1950s):


This is about as elegant as you'll ever see a push-pull EL84 amp get.

 

[Michaels HiFi]

What is the Golden Age?
I recently restored this bit of audio history (late 1950s):
View attachment 34701

This is about as elegant as you'll ever see a push-pull EL84 amp get.

My favorite age is the late 20's through the early 40's. I think it's all down hill from there in regards to tube production.

Imagine having a JBL Paragon or the last series of their Hartsfields? Or better yet giant WE horns and even some Altec's?

Glorious.

Amps are different and you can easily get great sound a couple of decades later - all in my personal opinion of course.

That late 50's amp is certainly part of the time when audio was great. and looks great.

 

[Michaels HiFi]

Top is restored after 25++ hours of work.

Bottom photo is as received on this 1940 tube tester.

 

[treitz3]

Man, that's nice. Great job!

Tom

 

[Michaels HiFi]

Man, that's nice. Great job!

Tom

Thank you Tom. I have no idea what I am doing and completely learning as I go.

 

[atmasphere]

Imagine having a JBL Paragon or the last series of their Hartsfields?

John Wolff of Classic Audio Loudspeakers has done a lot of that. He has both the big and the small Paragons in mint condition in his listening room, and as you might know has been making a very faithful reproduction of the Hartsfield for over 30 years.

He's done a lot of work advancing the Hartsfield, improving the bass, midrange and highs as well as the crossover. Its a speaker I could easily live with them the rest of my life.

I remember hearing it for the first time at CES about 1991. It was huge fun! I talked to Frank Doris (of TAS) that day and he commented that those speakers had something special he felt had been missing in modern speakers for a long time.

 

[Michaels HiFi]

John Wolff of Classic Audio Loudspeakers has done a lot of that. He has both the big and the small Paragons in mint condition in his listening room, and as you might know has been making a very faithful reproduction of the Hartsfield for over 30 years.

He's done a lot of work advancing the Hartsfield, improving the bass, midrange and highs as well as the crossover. Its a speaker I could easily live with them the rest of my life.

I remember hearing it for the first time at CES about 1991. It was huge fun! I talked to Frank Doris (of TAS) that day and he commented that those speakers had something special he felt had been missing in modern speakers for a long time.

He had the Hartsfield's at the Dallas show. They sounded fantastic. Definitely a speaker I'd love to own but will never happen.

 

[Michaels HiFi]

Sometimes the vintage hifi audio refurbishment process is less glorious than sanding smooth with a new Festool sander, mixing up a custom oil finish, or hand polishing to a nice sheen.

Sometimes it's the little things - such as removing 90 years of rust off the original hardware.

I'm going to now hand scratch clean them with an abrasive fiberglass tool (second pic).

 

[Michaels HiFi]

Spent several hours today working through a progressive cleaning of the faceplate.

The challenge isn't necessarily getting the gunk off or even getting it shiny again - the challenge is going all that while not unintentionally removing the gold lettering on the face plate.

 

[Michaels HiFi]

I cleaned with a brush, then a giant special eraser this tube chart on one of my 1935 tube testers. Then I applied this wax on it that they use at museums to protect and nourish historic documents and photos.

 

[atmasphere]

I cleaned with a brush, then a giant special eraser this tube chart on one of my 1935 tube testers. Then I applied this wax on it that they use at museums to protect and nourish historic documents and photos.

View attachment 34726

Pretty important document for that tester! Was it mounted to the case and will you re-install it? Are you doing any refurbishment to the circuit?

 

[Michaels HiFi]

Pretty important document for that tester! Was it mounted to the case and will you re-install it? Are you doing any refurbishment to the circuit?

Yes it was mounted on the inside lid - here is a before pic. I'm going to reinstall it after I finish restoring the wood.

Definitely going to try and teach myself how to test and update the internals as well. Typically at the very least they all need a new power cord and updated caps.

 

[atmasphere]

A lot of testers have a tube rectifier inside. Sometimes that can be replaced with a solid state rectifier but you'd have to do some research to see if that is so. My Hickok 539B uses an 83 mercury vapor rectifier (I think they did this to reduce Voltage drop across it). I have a spare on hand but apparently there is a solid state replacement available. It might be a while- I bought that tester at an ham radio swap meet back in the 80s and its still got the original tubes and works fine.

 

[Michaels HiFi]

A lot of testers have a tube rectifier inside. Sometimes that can be replaced with a solid state rectifier but you'd have to do some research to see if that is so. My Hickok 539B uses an 83 mercury vapor rectifier (I think they did this to reduce Voltage drop across it). I have a spare on hand but apparently there is a solid state replacement available. It might be a while- I bought that tester at an ham radio swap meet back in the 80s and its still got the original tubes and works fine.

Very true. Also usually the switches usually need some serious cleaning.

It's interesting in talking with some guys who have dedicated their lives to working on tube testers: they say if you add in a solid state rectifier it* may* affect the accuracy over different tubes in different ways if that is not taken into account when switching it over. They of on to say some solid state rectifiers are more accurate than others, and in some units it is an issue and some not.

The 539B you have is a great tester.

I have on order a refurbished Western Electric 15750 which is an upgraded 539C with filtered DC voltage and other tweaks to allow more accurate readings on the WE style tubes that I heavily use.

For now my reference is a custom refurbished TV-7. It's the B version which many consider the best of all the versions. I've had many testers come and go, and my favorite combo for what I keep on hand (other than the super-vintage testers which I love from the 1930's) is the TV-7 and Western Electric.

The old testers from the 1930's do great by me as they were designed for tubes such as 45's, 300b's, 2A3's, 80's etc. All the old time tubes I use. As you get into "newer" testers from the 50's and 60's they tend to either omit the 4 pin socket or are not really designed to give an accurate reading on those tubes.

I'm sure you already know all this being in the amp business as long as you have.

 

[atmasphere]

One nice thing about the Hickok is if the tube information isn't listed, you can still figure out how to test it since the switches relate directly to the pin base of the tube. Then the only tricky bit is sorting the readings you're looking for. A tube manual is handy for that.

Have you sorted out if the meter movement is OK?