Vintage electronics thread

[ERD50]

Well, most class A guitar amps are AB, but with only one power tube, it would be class A, no? I studied the implications some years ago, and have since forgotten, but have some old lab books and schematics for if/when I actually decide to do this...

Is the Vox AC-30 really class A?

Well, the line blurs as you go from Class-B to Class-AB with higher and higher bias currents. Looking at that article, and another I found, it seems like some consider that if you bias it heavy enough the push-pull pair are operating together as Class A.

That's not the defintition I'm familiar with from school (long time ago and I may have forgotten or fallen asleep), or from the Hi-Fi world. I recall Class-A as being a device (or parallel devices) biased right in the middle and it would swing from + to - rails. It always used the same amount of average power supply current regardless of the amount of signal fed into it. IOW, if an 'ideal' Class A amp was biased at 1A, and it could swing to zero and up to 2A, it would draw 1A idle and over one cycle of input it would also draw an average of 1A (average 0A and 2A).

A Class AB would draw its bias current at idle, and then it would draw more when a signal is applied. The blurry line is when you bias it all the way up to 1A as in our class A. I think distortion products would still be slightly different (not better/worse - the ear determines that), as the conduction shifts from one device to another, versus being on a continuos slope of a single device. I don't know which sounds better for guitar, but those sites should give about as many opinions on that as asking what SWR is best would here.

Bottom line, it would be cool to build your own, regardless what form it was in. Or multiple and compare. Once you retire, you're gonna need something to keep you busy

edit/add: I have not worked with tubes much, but I think some of those power tubes are two devices in one glass envelope. So 'one tube' could be a push-pull pair? A dual Triode/Pentode?


-ERD50

 

[HFWR]

Many guitar preamp tubes, such as the 12AX7, are dual triode, but popular power tubes, such as 6v6, 6L6, El84, and EL34, are single pentodes.

 

[Nodak]

I built some 2A3 Single Ended Triode amp kits and pre-amps put out by www.bottlehead.com. They sound fantastic, and were fun to do.

Not technically vintage, but certainly in the spirit of this thread.

The amp in the bottom of that Scott radio of mine is 35 watt class A using 4 2A3s in a push pull cascaded config.

 

[Gumby]

So what is your oldest working gear?

I am a sucker for old stuff that still works (or has been made to work again), especially old test gear. As I mentioned earlier, I recently restored a Model CB-1-60 capacitor analyzer, originally built in 1936 by the Solar Manufacturing Corporation of Bayonne, NJ. I also have working Variac Model 200-CM built by General Radio Corporation of Cambridge, Mass. in 1935, and a working Model 630 tube tester built by the Jackson Electric Instrument Company of Dayton, Ohio in 1937. My multi-meter is a Simpson model 260-2 from the late 40s.

So what's your oldest working equipment?

 

[HFWR]

So what's your oldest working equipment?

 

[Gumby]

Maybe I should have been more specific -- ". . . electronic equipment?"

 

[REWahoo]

Maybe I should have been more specific -- ". . . electronic equipment?"

Yep, that's probably better. For a moment I thought about responding to this...

I am a sucker for old stuff that still works...

...with "What a coincidence - so is my DW!"

 

[ERD50]

RE: Class A, AB, etc...

Many guitar preamp tubes, such as the 12AX7, are dual triode, but popular power tubes, such as 6v6, 6L6, El84, and EL34, are single pentodes.

Makes sense then. So if one of those single power tubes is the output of a guitar amp, it seems it would have to be 'Class A' then. You gotta have two to tango for a push-pull Class B/AB. At least as far as I can determine.

I was just surprised they would run them that way. A Class A really sucks up the power.

-ERD50

 

[Gumby]

Yep, that's probably better. For a moment I thought about responding to this......with "What a coincidence - so is my DW!"

Don't tell me -- she's a steampunk fan.

 

[Ed_The_Gypsy]

Bellingham, Washington, has a nice radio museum, started by an ex-Microsoftie, I gather. It covers electronics up to but not including transistors. If you are in the area, check it out.

 

[ls99]

My Grid Dip Meter.

Made by Measurements, later to become Boonton. Made about 1948-49. Had it about 30 yrs. Works like a charm, use it often. Never thought about how old it is until yesterday's query by Gumby. Looked it up, actually found a downloadable manual. Never had a manual for it. Now I do, yay! Model 59 Sno 582

This thing just works, never had a lick trouble with it.. Read in the manual that all tubes were conservatively rated, they are still the original. Works up to 400 Mhz, now I'm curious, the manual said the made a tuning head for it that was good to 800 Mhz or more. I'll start looking.

 

[bruce1]

Here is my oldest working Radio 1926/27 Westinghouse Batteryless. The second is my best working, a Phonola with a pair of 6F6 in Push Pull Configuration.

 

[bruce1]

Home Brew From the Twenties

These are a pair of homebrew receivers from the twenties or early thirties

 

[bruce1]

The New Westinghouse 55

The New Westinghouse 55

 

[Gumby]

Wow! That's quite a collection. My oldest audio stuff is a turntable from 1957 and a receiver from 1963 (both Voice of Music made in Benton Harbor, Mich.)

 

[HFWR]

Wow! That's quite a collection. My oldest audio stuff is a turntable from 1957 and a receiver from 1963 (both Voice of Music made in Benton Harbor, Mich.)

Back when stuff was made here...

 

[gwix98]

OH boy....... this is a good thread!

Wish I had more digital pics ready to post. These pics were taken of stuff I'm selling or have sold:

Collins S Line - 75S3-C 32S-3 312b-4 516F-2

Collins 51S-1

Drake C Line - R4-C T4X-C

Drake 2-B

Hallicrafters SX-100

Misc mountain of other "stuff" qualifying me as a guy who needs to thin the collection!

This is primarily ham radio related, not quite as vintage as the example above, but vintage just the same.

Hi youbet,

Sure remember and am familiar with those radios (WA7GWX),
Always wanted an "S" line or Drake line when I was a novice in
1967. Love to see it! Hope all is well. Nice to be back on this board again.

 

[Gumby]

Back when stuff was made here...

I have been making every effort to buy only stuff made in the US, but it is incredibly difficult. Recently, I wanted a swivel fan for my workbench in the garage, but I could not find a new one that was not made in China. So I ended up buying a 1947 vintage GE Vortalex fan on ebay.

 

[Ed_The_Gypsy]

I still have
a) a portable (it has a handle!) vacuum tube Tektronix oscilloscope, and
b) a Sol-20 microcomputer (sorry, post-transistor).

 

[Gumby]

To follow up on a theme started by bruce1, I have been pleased to use the following vendors:

Cloth covered wire from Sundial Wire cloth-covered wire of all types.

Allied Electronics capacitors. resistors and most other components

Welcome to TubeDepot.com! amazing stock of new and NOS vacuum tubes

TubeSound sells a variety of tube-related stuff, but the free information is the most important part of the site. He knows everything there is to know about tube testers.

I also recommend this site for information on a wide range of electronic topics

DIY Audio Articles

 

[bruce1]

I still have
a) a portable (it has a handle!) vacuum tube Tektronix oscilloscope, and
b) a Sol-20 microcomputer (sorry, post-transistor).

I remember a Tektronix spectrum analyzer from my early career, about 1975, that almost took two people to move it. It actually had two handles.

More old radios

First is a 1926 Victor that uses peanut tubes and was made by Northern Electric in Montreal on Oct 26 1926. The inspection tag is still intact.

The second is a Pontiac made in Walkerville Ontario. (now part of Windsor)

Last is an intact but very dead battery I found in the Victor

 

[Nodak]

Ran across this very rough Philco radio phonograph and don't know if it's worth trying to fix.

 

[Keim]

The electronics look straightforward, if you have a tube tester and a DVM.

But that case looks challenging. Especially the warped veneer.

Does the phonograph come out, like a drawer?

 

[ls99]

If your woodworking skills are great, go for it. The guts seem fairly good.

I would not even attempt the woodwork.

Add: On second look, the turntable is likely beyond fix. The idler wheel under the turntable is likely shot. Does not look like a direct drive.

 

[Nodak]

The phonograph does not slide out like a drawer. The whole thing is very unusual and I don't think I have anywhere near the skills to fix it. There is a weird linkage that lowers the spindle when the front is opened. It looks like the intention was to slide a record in, close the front which would raise the spindle and from there I don't know how it worked. The more I look at it the more I think it is only good for parts.