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Driveby!

thefragger

thefragger

Certified Crazy.
Story!!

There was this estate sale going on near my house maybe a month or two ago for an old lady that lived to be 100 and had passed away, so I thought I'd check it out. I missed out on some Sonab OB11 (thread on that in the speaker forum) so I was kinda bummed.

In the basement was this HUGE beat-up and water-damaged amp that was singing. The sticker said $100. F that. I checked the back anyways-- all tubes glowing away, very cool. I walked out with a mechanically-challenged, tube amplified phonograph / end table. A few weeks pass and they're at it again, this time the console's at $50, then the next day at $25. Still, I have no room for it and it's not the prettiest thing I've seen, besides, I had already bought the little phonograph that I got running. I reminisced with one of the lady's daughters about the little guy. She's extremely pleased that I got it running, but won't sell my the Sonab's because someone earlier called dibs. Rats.

That night everything that didn't sell is on the front lawn with a sign; 'FREE!!' I figured that this was my chance. A few guys might remember this from the chat room. It was around 11pm and I was pacing in my mind about going and pulling out the amp. Then it starts to rain. Well, for sure the console's wrecked now. I pack some tools into my backpack and wait for a lull in the storm. 11.46p I made my move. 12.15 I was back home dripping wet and ecstatic.

Everything went onto the shelves on my workbench because I had a few other projects I had to get out of the way first.

I got to it tonight and I powered it up by plugging it in, sans variac / series-bulb-trick. I was freaking out that it would explode all over me. What a rush! Of course, I forgot to not the knobs and what each one did, so I fiddled around with them while playing with the tuner and I got sound! Aha! It works! One of the 6AQ5's was glowing blue so that was kinda cool, turned it off and back on and the blue was replaced with the subtle orange glow.

I think it's the coolest thing since sliced break. I'm frightened to death by it, but I'm going to build it a pretty cage to live in. I grabbed the original glass, too, but forgot the dial knobs and tuning eye hood.

Lets have some fun.



Tube layout and tag from the back of the console


Top shot, front is at the bottom.


The front of the unit. From what I can tell the knobs are Bass (Tone?), Power / Volume, Function Select, and Tune.



It's alive! The power light turns on and off when it feels like it (little bulb near the bottom of my soldering iron holder).


Tuning eye's a little weak (edited in Photoshop) and it doesn't really change when I tune in and out...


Little bit of corrosion on the power transformer. I didn't want to touch it, but it was maybe on for 5 minutes. The output transformer is under the chassis.


The speaker. I forgot to take a photo of the back or make note of anything that's written. Will do tomorrow.


Backside connectors. One of the lamp cords is power in, the other fed power to the TT. RCA connector is PHONO. Screw terminals is for Antenna and Ground. The twisted pair goes to the power lamp.


Photos with a pencil for scale.


Pretty glowey shot! The one that was blue is in the middle of the group.
​


How'd I do for a first-timer / experimentation unit?
 
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you gott it PhiLLip!! As we say in the Army... better than a kick in teh nutz with a frozen mukluk! :)
 
Hello,

Interesting chassis here. Are you sure this is a mono unit? If you see only one
output transformer under the chassis, it must be mono, but then the two
6AQ5s indicate it is a push-pull output setup, making it more interesting than
most of those AM-phono consoles. Also, the presence of two rectifiers (6X4)
with such a small tube count is interesting. You will find that good 6U5 tubes
are hard to come by, be sure to buy from a reliable seller. Good luck!
 
Hey, nice snag. It looks like you'll get a few hours of fun and entertainment out of restoring and breathing new life into that. I'd go back and get the knobs and dial glass, if still there.

Thanks for all the great pics!:thmbsp:
 
Tinkerbelle said:
Hey, nice snag. It looks like you'll get a few hours of fun and entertainment out of restoring and breathing new life into that. I'd go back and get the knobs and dial glass, if still there.

Thanks for all the great pics!:thmbsp:
Click to expand...

I made sure to snag the glass but in my haste I forgot the knobs. The box had disappeared and I couldn't find the knobs in the grass the next morning. There are some old knobs at the local surplus shop-- I'll grab a set from them, maybe...

I want to build a really nice box for this little guy. It's definitely a PP mono amp; all I saw was one output transformer underneath from what I remember.

More photos to follow...
Philip.
 
Here are the photos I promised.


This is the company who I presume made all the parts that went into this unit.


More detailed photos of the speaker.


An overall and detail shots of underneath the chassis


Angled shots of under the chassis to show the sizes of components, also the bottom cover without any signs of leaking components nor melted wax.
​


Cool?
 
That front end of that set looks like it has shortwave bands as well as regular AM standard broadcast. The SW bands will need a length of wire of tens of feet long to receive anything. Probably that set of terminals on the back.
 
wa2ise said:
That front end of that set looks like it has shortwave bands as well as regular AM standard broadcast. The SW bands will need a length of wire of tens of feet long to receive anything. Probably that set of terminals on the back.
Click to expand...

It had two band of shortwave, AM, and phono, from what I remember. What's a good length of wire for the antenna? Is there any way to pick up FM?

Also, what can I plug into the phono connector? I have no idea what the original TT was so I'm not sure what level it's expecting... would there be any problems if I fed it a line out from my MP3 player?


Philip.
 
thefragger said:
It had two band of shortwave, AM, and phono, from what I remember. What's a good length of wire for the antenna? Is there any way to pick up FM?
Click to expand...

The length of the antenna isn't that critical. 20 or 30 feet would be more than enough, ten feet should let you hear something. As for FM, you'd need an external FM tuner, maybe one that is part of an MP3 player.

As for where the old phono input was, there should be a selector switch that switches the audio signals, likely just ahead of the volume control. One switch selection should go to the phono input, and another to the AM detector circuit. This switch might be part of the band switch.
 
wa2ise said:
The length of the antenna isn't that critical. 20 or 30 feet would be more than enough, ten feet should let you hear something. As for FM, you'd need an external FM tuner, maybe one that is part of an MP3 player.
Click to expand...

Thanks for the confirmation.


As for where the old phono input was, there should be a selector switch that switches the audio signals, likely just ahead of the volume control. One switch selection should go to the phono input, and another to the AM detector circuit. This switch might be part of the band switch.
Click to expand...

My question was more geared towards whether sending a signal that was higher than the amp was expecting through the phono would be bad or not.
 
thefragger said:
My question was more geared towards whether sending a signal that was higher than the amp was expecting through the phono would be bad or not.
Click to expand...

turntables back then usually produced a fairly high signal level, likely the same level you'd get from an MP3 player. Just set the volume on the set fairly low when you first try it. It should work fine.
 
That's a rare Rogers, much-sought after by collectors. Most of them have one problem in common, though: they are usually found missing the dial knobs and tuning eye hood. Because of the widespread shortage of these particular items, they are worth about a thousand bucks apiece to hard-core collectors, even more than the amp itself.

Just kidding you, of course! :D You scored a nice-looking and interesting amp (along with the rest), with a well-told and entertaining story behind it. Thanks for sharing; looking forward to future instalments of the saga.

Well done :thmbsp: , and enjoy the :music: !
 
There may be an equalization curve for the phono input, so you may end up with a lot more bass than you anticipated.
 
Arkay said:
That's a rare Rogers, much-sought after by collectors. Most of them have one problem in common, though: they are usually found missing the dial knobs and tuning eye hood. Because of the widespread shortage of these particular items, they are worth about a thousand bucks apiece to hard-core collectors, even more than the amp itself.

Just kidding you, of course! :D You scored a nice-looking and interesting amp (along with the rest), with a well-told and entertaining story behind it. Thanks for sharing; looking forward to future instalments of the saga.

Well done :thmbsp: , and enjoy the :music: !
Click to expand...

Maaan! You had me going!! I haven't had much time to work on it recently, but I'll keep posting updates when I get around to it (all I've got are square ones right now... )

Thanks for the kind words!


Philip.
 
I pushed this little amp with Van Halen's Best Of album. I had no idea tubes gave off so much heat! But it sounded great-- aside from scratchy volume and tone pots.
 
I have a very similar "parts" chassis. Mine only has AM front end and a concentric bass/treble control rather than a single tone pot.

These are the knobs. The tone is in 2 pieces (bass/treble) If you want them, you can have them. You can also have the ganged tone pot if you want to mod your unit.
 

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willyrover said:
I have a very similar "parts" chassis. Mine only has AM front end and a concentric bass/treble control rather than a single tone pot.

These are the knobs. The tone is in 2 pieces (bass/treble) If you want them, you can have them. You can also have the ganged tone pot if you want to mod your unit.
Click to expand...

That's pretty awesome of you to offer! Hell, if you're not using any of those knobs or that pot I'd be more than happy to receive them! This could be interesting learning how to mod the amp for separate treble / bass controls.

Thanks a million!


Philip.
 
I clipped out the tone control circuit and labeled the 3 connection points. (IN, OUT, GROUND(?)) On mine the tone control connects between a 6AT6 and a 12AX7.

It "might" be as easy as replacing the resistors and caps with new ones and swapping your tone network with this one however yours uses a second 6AT6 instead of a 12AX7. I think this leaves you with one less gain stage which will likely affect how this will or won't work
 

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