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Old 12th July 2005, 03:50 PM   #1
Trout is offline Trout  United States
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Talking Unusual Motorola Console

Oh My I love summer outdoor auction season.

Found another unusual Motorola Console this past weekend.

I really dont understand how these babies work though, 3 Output channels.
Left, Right, & Bass.

As It sits, Center(bass) and Right channel are VERY Loud, Left Channel appears dead. I have only just begun trying to figure out the point of failure. I suspect its off chassis on either the preamp chassis, Or the weird speaker test switches. All the tubes check out fine, In fact they are still over 100% on my tester. Nothing looks burnt.

Photos: Chassis label ,Top View , Huge Bottom View

Interesting to me was the nearly exclusive use of ceramic caps. The sound quality from the 2 working channels is outstanding and well defined.

I have never seen a console utilizing ECL82/6BM8's prior to this unit.
Its not uncommon to see motorolas using 3 output stages I guess, This is the second unit I have gotten this summer,
The Other Using 2- 6V6 on bass channel, And 2 EL84 SE for left & right channels.
Gene
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Old 12th July 2005, 06:19 PM   #2
Trout is offline Trout  United States
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After Further digging in this console, as it turns out, The preamp powers off of the power amp chassis via a long cord. The Tuner on the other hand actually is a free standing (has its own power supply) Unit.

Photos below are of the preamp chassis. A bit more conventional I might add.
Label Preamp Chassis Large Chassis Underside

Getting close to setting it up minus the speaker test selector switch and extra junk not needed. Then I will try to locate the reason for no output on left channel.

<Crossing Fingers>
Gene
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Old 12th July 2005, 07:09 PM   #3
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Default Re: Unusual Motorola Console

Quote:
Originally posted by Trout
Oh My I love summer outdoor auction season.

...I really dont understand how these babies work though, 3 Output channels.
Left, Right, & Bass.

...Gene

Gene,
When I was a kid we had a console with three channels. IIRC the bass channel worked kind of like a modern subwoofer in that bass from both left and right channels were fed into it. The left and right channels, handled only the higher frequencies (I have no idea what the XO point would be) and could be lower power with less expensive OPTs.

I didn't look closely at the bottom chassis photo but I'm guessing you'll find some sort of XO combining the two main channels.
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Old 12th July 2005, 07:20 PM   #4
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is that a copper chassis?

3x 6BM8 PP time to do up the Yves/gingertube style Frugal-phile(tm) amp

dave
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Old 12th July 2005, 09:35 PM   #5
Trout is offline Trout  United States
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Quote:
Originally posted by planet10
is that a copper chassis?

3x 6BM8 PP time to do up the Yves/gingertube style Frugal-phile(tm) amp

dave

haha, When I first opened the unit and saw all that copper, I was Thinking SWEEEEEEEEEEEEEEEEEEEEEEEEEEEET!

But sadly, its some kinda of plated steel. Theres a couple spots where oxidation has revealed the steal underneath.

Im Really liking all the British tubes relabeled Motorola!

Although, The 2-12AX7's in the preamp were I beleive GE.

Gene
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Old 12th July 2005, 10:48 PM   #6
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More Info:

The Speakers are set up , 5 1/4 and 3 1/2 on each channel (L & R)
The Center Has a 12 inch Golden Voice Motorola ( Looks like Alnico)

I have a schematic for a different (working)unit that I bought earlier this summer, AMP PreAmp

Possibly it will give some insight as to how motorola did things back then. That particular unit has ended up in my collection and in fact gets used almost daily. My younger brother(also a musician) Stopped over one evening to hear that unit, 6 Hours of Vinyl later, I told him to go home! lol
He has been hitting garage sales ever since!

I now have a line on 3 more consoles for this weekend. The more interesting one is a very old Dumont with 2 floor speaker units.
I am unsure of the other 2 brands as its at a local auction.

Picture Of Dumont

Gene
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Old 13th July 2005, 12:53 AM   #7
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Quote:
Originally posted by Trout
Im Really liking all the British tubes relabeled Motorola!
Made in England or made in Gt Britain?

dave
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Old 13th July 2005, 11:08 AM   #8
Trout is offline Trout  United States
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Quote:
Originally posted by planet10


Made in England or made in Gt Britain?

dave

Great Britain, Very Clean and date coded, Though I find the codes on these things totally confusing.

So far of the 3 motorolas and 2 zeniths I have recovered this summer 97% of the tubes tested over 95%. Most still over 100% and only 2 at about 895. Pretty damn good.

2 Old RCA /Cunningham 6V6's Testing at 103% matched and date coded 1948. Truely a tribute to the craftsmanship of the era.
gene
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Old 13th July 2005, 12:47 PM   #9
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Default Re: Unusual Motorola Console

Quote:
Originally posted by Trout

Interesting to me was the nearly exclusive use of ceramic caps. The sound quality from the 2 working channels is outstanding and well defined.
Hahahah. Now you know what all the capacitophiles have feared men discovering.

The chassis is in wonderful condition, almost mint! I've never seen one that nice. Even the tone amp merely has a layer of dust. The copper plated chassis I have (from a Westinghouse radio) is all rusted to heck. You should mask that off and give it a spritz of laquer to ensure it stays that way, if it hasn't had it already.
Thing that sucks about those chassis is they are anti-galvanized: the iron underneath actually protects the copper! Unlike zinc plating, which corrodes sacrificially instead of the iron. That's why you'll need a layer of paint to keep it nice.

Tim
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Old 13th July 2005, 02:16 PM   #10
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Default Re: Re: Unusual Motorola Console

Quote:
Originally posted by Sch3mat1c
The chassis is in wonderful condition, almost mint! I've never seen one that nice. Even the tone amp merely has a layer of dust. Tim
Hey, The chassis in my other motorola (schematics above)has what appears to be a gold anodized looking finish. It makes this one look bad.

I wonder if some kind of copper cleaner/polish should be used to bring up the appearance a little. Its only has a couple green spots and only on the outside. The inner chassis is still looking factory new.
Gene
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