Dukane content

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Thanks Boss Man   

I got to looking for some old manuals instructions catalogues online not much luck I did see one 1982 catalog for sale and the equipment looked different (more modern) than these so I'm guessing it's 70s or earlier

The guy I got it from bought tons of stuff at auction and much of it came from Lamar University in Beaumont it's very likely the source of this stuff.  Furthermore the old Lamar University yearbooks are scanned and viewable online (Texas Portal to History)...so I have looked and tried to find a pic of this in service but have yet to.

 

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Anyhow being conscious that we needed info on the transformer(s) it dawned on me that I could look inside and maybe get some info

Front cover off
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Unfortunately the bottom of the chassis obscures any viewing and surprise looks like an additional transformer
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Bottom of small transformer more Dukane numbers
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Right side
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I thought it was a trip they had a light bulb inside if nobody could see it pulled it out looks open it did not illuminate
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But then I saw the orange lense on the front cover
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But anyhow sir thanks for the assignment will get that for you 

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Resistance values obtained
Basically about 2.5 ohm between the bottom three pairs and lower between 7-8
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The jumpered resistance maybe means they are in parallel? Idk
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Anyhow I still need to hook up a speaker and try it jumpered.

 

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Okay I ran it thru an 8 ohm speaker and it works pretty good

But I'm perplexed that a square wave and sawtooth sound kinda the same as the sin 

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Hey gotta love noobies making things more complicated  so I decided to try and get some scope images

The smaller one (output) is channel 2 and had to put it on 10x and big volts per div
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It still was extremely erratic and would clip at the drop of a hat You cannot view this attachment.

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I am forced to realize that this device is capable of increasing signal.  And chopping the end of its peaks off as well.

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When I was adjusting the signal level I had to act like a safecracker gingerly making infinitesimal adjustments or the whole thing would go out the window 

There was definitely a sweet spot that needed to be adhered to.

Btw pretty cool I had not seen this before and noticed it earlier 

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I have to say that observing the signal in and signal out was a major epiphany (?) for me.  It actually blew my mind.
I know it sounds simple of course if you asked anybody what an amplifier does they would laugh and give an obvious (an correct) answer.
Something small (quiet) goes in and something big (loud) comes out.  Easy enough right 

But to see the same sin or sawtooth emerge from the output multiple times larger to where the entire thing wasn't visible until a different scale was used....ok that was a trip. 

And I'm not saying I know how it does it because I don't yet but many times I lose focus and don't grasp what is happening and well 🙈 seeing is believing 

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Ok it was a frustrating evening but it ended somewhat in victory 

I wanted to decipher this enigma machine and play something through it. 
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I started out probing connections and turning selector switches etc while in continuity test and a couple times heard a faint sound or two, not from the multimeter but like the speaker was getting DC or something.  Finally I just turned on an amp and tuner
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ran some speaker wires and got really frustrated couldnt get sound whatsoever.  It's one speaker with two transformers and that was daunting but I looked and the end of the road on each side was normal speaker inputs a pair on each side.  Connecting speaker wires to them got sound 
So I went back to the array of terminals on the back and couldn't get anything at all.
I finally connected 1 khz tone and managed to get sound then removed that and added a pair of speaker wires to each side and it works 

At one time I wondered if the output from the amp/tuner wasn't strong enough to barrel through the transformer(s) but it sounds good now.

However the volume knob on the amp is like half way and that would be very loud with the normal 8ohm speakers.

Right now I'm listening to a college football game at mild volume.

It's been a busy day but it's cool playing around with this stuff 

Before I hit post I was like woah see if the meters are working and when i turned it around they were pegged all the way to the right 
In a frantic attempt to remedy that I noticed the level controls on the front of the panel didnt seem to do anything

Finally turning it down at the amp got them down a little.  You cannot view this attachment.

But they are still bouncing in the red like mad and it's not loud at all....idk

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There is yet more Dukane content 

I wanted to try a guitar thru it so I used a speaker out of a three way stereo speaker system
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Or if you prefer
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and ran preamp out of the Peavey Rage 108

(with the Peavey speaker disconnected)

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I played for a while and was taking a break suddenly the speaker started pulsating real bad  I turned the Peavey off still pulsating I'm guessing after having been on for a while some DC made it through (just a guess...I'm fixing to check it)

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Ok it seems the unprovoked appearance of the jackhammer speaker is pulsating bipolar DC.

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I had turned it off conne my meter turned it back on played for a bit wondering if it would happen again and it did.  Out of nowhere starts pulsating like 90 bpm and the values on the meter jump all around POS and neg.

Not too worried about now but it's interesting must be a bad component somewhere.

Pretty wild I have never seen anything like that.  It wasn't loud just the speaker cone moving in and out .   

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Possibly what is called 'motorboating'? 
Often caused by dried up old capacitors no longer doing their job.

[Miyagi_83]

Possibly what is called 'motorboating'?

Something like this

or like this (@04:18)

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There are tens or hundreds of thousands of those gray capacitors out there working fine, so for the guy in that video to say you should replace them on sight whether they are bad or not is kind of silly.  'If it ain't broke don't fix it'.
I guess it's a money maker though. 

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Thanks guys I wish I had tried a few things like reversing the speaker wires seems when I had the cover off I saw something indicating polarity but idk

Seems like there won't be much of a future for the amp which is a shame it's ridiculous how nicely built it is.  I definitely have plans for the panel with the meters and speaker I want to connect a tuner to it to listen to ESPN etc.

And that requires an amp but not 50 watts...

But I like the amp and will continue playing and learning about with it

[Miyagi_83]

There are tens or hundreds of thousands of those gray capacitors out there working fine, so for the guy in that video to say you should replace them on sight whether they are bad or not is kind of silly.  'If it ain't broke don't fix it'.
I guess it's a money maker though. 

I agree. Perhaps he thought that caps change color as they age, kinda like hair does