Big thanks to Mick for encouraging me (almost a year ago) to try and get something out of this ancient artifact :dbtu:
I wanted to put on my big ugly dim bulb tester but was kinda perplexed by the results.
60w bulb unscrewed and 43w bulb screwed in
IMG_20241109_170929670_HDR.jpg
Now 60w bulb screwed in and 43w bulb unscrewed
IMG_20241109_170908333_HDR.jpg
And both screwed in
IMG_20241109_170850738_HDR.jpg
I didn't know if this was good or bad...they both glowed but more pink and orange not like a bright light.
So I figured ok might as well try something but maybe it's got blown outputs (?)
I grabbed a speaker and not having the slightest idea where to attach I picked two terminals and attached them and when I plugged it back in I was stunned to hear some noise :lmao:
I grabbed my cable to attach a signal and I can't believe it works :loco 8| xP :grr <3) :dbtu:
But when I increased signal output it got really ugly sounding like it was in a blender :grr
So I removed some jumpers that had been there probably forty or fifty years and tried it again this time nice and clean :dbtu:
IMG_20241109_174703937_HDR.jpg
Also I saw the bulb would get brighter when I increased signal 🚦
If you are wondering there are no controls or power switch.
It came with another piece that had knobs and level controls and one medium sized speaker.
Btw attached to the power cord were a couple of tags like instructions how to attach speakers
IMG_20241109_174918997.jpg
So wow I'm really glad that I tried it and got sound thanks again Mick <3)
If I can get it set up to listen to ball games from a tuner or maybe even some music man that would be awesome :tu:
Hey guys do you think that is a transformer and a choke or two transformers :loco
View from the top
IMG_20241109_174908357_HDR.jpg
IMG_20241109_181442600.jpg
IMG_20241109_181447983.jpg
Here is the front of the amp...no controls switches or anything
IMG_20241109_182412399_HDR.jpg
And here is the "controller" :loco
IMG_20241109_182744387_HDR.jpg
Rear
IMG_20241109_182809924_HDR.jpg
Lots of terminals
IMG_20241109_182819610_HDR.jpg
The speaker has some multi tab transformers
IMG_20241109_182827744.jpg
And all put back in their home for now
IMG_20241109_183332839.jpg
xP
So now I have a purpose in life
Find out how to connect a pair of normal 8ohm speakers and a tuner to the controller via the level control
Then connect that to the amp or vice versa
The controller also has a power switch on the front so I have to find out how to connect the mains
Shouldnt be too bad compared to trying to install in a university auditorium :-X
Quote from: saturated on November 09, 2024, 07:13:03 PMHey guys do you think that is a transformer and a choke or two transformers :loco
As a wild guess, the one closer to the power cord is most probably the power transformer. The other one could be a choke, an output transformer, a line transformer or something else. I would take a look inside to see what each one is connected to.
With the mains unplugged and caps discharged of course. (Hope I didn't come off as condescending or anything).
EDIT: I did a quick search for this model's circuit diagram, but couldn't find anything. Either nobody uploaded it or it's unavailable in my location.
Thank you sir :tu:
After scouring the interwebz for a while it seems the 25v configuration wasnt really designed for 8 ohm aka "normal speakers" but will suffice. And I think that's what Mick was talking about eleven months ago. 8|
Causing further complications is well two eight ohm speakers in parallel.... :grr
Also I guess obviously it's gonna be mono...I get it it's not a Pioneer or Marantz..but I'm befuddled about why each "monitor selector" has eight positions but there are only four positions on the back.
When I get time I will do some continuity tests on the controller unit and propose some possible configuration(s).
When I ran signal into it I was able to control the level....had I just connected a tuner to it I wonder how loud it would have been :lmao:
I guess that I need to jumper 1-3-5 and connect neg or pos from two speakers then jumper 2-4-6 and connect other two POS or neg then each one of those speaker wires out goes to a "level" control :loco
Also with the 25v configuration using 1-3-5 and 2-4-6....what's up with 7 and 8 :grr
Might have to get some voltage readings.
The multimeter is the most important piece of equipment :trouble
From memory I found a connection diagram for that PA system, PA systems do not use a speaker output but they use a voltage output that feeds into a transformer at each speaker.
It is done that way so you can have really long cable runs with less losses at the speakers.
If you look for audio transformers you will find the correct type of transformers to use since they are rated at 100V, 70V, etc on the input and the output is rated at watts (usually for an 8 ohm speaker)
I have 2 small transformers like that that I can use as an output transformer in a 1-2 watt tube amp, even though they are not meant for that.
Here is a link to the ones Mouser have for sale:
https://au.mouser.com/c/power/transformers/audio-signal-transformers/?m=Visaton&secondary%20impedance=4%20Ohms~~8%20Ohms%2C%204%20Ohms&rp=power%2Ftransformers%2Faudio-signal-transformers%7C~Secondary%20Impedance
The selector switch is most likely so they could send the sound to the right department, office, workshop, dispatch canteen etc.
they could also select the different wattage taps on the speaker transformers so it suited that area, I imagine the office would be less noisy then the workshop floor.
I think they could have used that unit almost anywhere since they were/are common in factories, shopping centres, train stations, clubs, and many more places.
Thank you sir :dbtu:
This is gonna be good I can learn something :tu: because right now it's blowing my mind.
So maybe I'm not jumping or configuring for 25 or 70v but rather connecting to the speaker terminals as is...
Also is there a correct term for this device (unless mother ship 🚢 is good 👍)
IMG_20241109_182744387_HDR.jpg
Is it possibly called a "transport" ?
I think I made a monumental discovery today
(Possible) Monumental discovery below:
I think I am missing and or need a preamp
:grr
As far as I can tell that unit is a 'Constant-Voltage' amplifier.
ie: A Public Address amplifier.
Yes, it needs a preamp of sorts.
If you look at the speaker in the other unit you will see it has 2 output transformers that is the type you need to drive 8 ohm speakers with the amp.
I am guessing that the speaker might have 2 voice coils or something to be needing 2 transformers.
Take a good look at those transformers and see if you can work out the input voltage, then you can use them to drive 2 separate 8 ohm speakers.
I found the post from December last year, I wrote this:
"I looked around at some Dukane amps and it seems some of them you could link terminal 1-3-5 and 2-4-6 and then you have the output for 8 ohm speakers.
I think they had 3 different coils that ran at 25 volt output, possibly 1-2, 3-4, 5-6 were the separate coils.
When you run them in parallel like I said above they became right for 8 ohm.
If you run them in series they form a 75 volt (70volt) output for PA speakers.
I think I can see a link between terminal 1-3-5 on your photo so it was running an 8 ohm speaker, there will be links between 2-4-6 as well.
Plug it in and see if you hear anything"
You should be able to check with a multimeter if you have 3 output coils on the back of those terminals.
Check for resistance between terminals 1-2, 3-4, 5-6.
Yes sir thanks to all I plan to do all of that and I thank you for letting me enjoy the journey :tu: one step at a time
:dbtu:
I don't want to bombard everybody with questions but I was looking at something old to pair it up with...I saw many "🎤 microphone 🎙� preamps looks like they have weird input connectors i don't think a mic preamp would work ?
Also those level controls on the mother ship did they run the speaker out through those to control volume ?
But anyway thanks my task at hand is measuring voltages on 1-2 3-4 5-6 7-8
:trouble
Ok I got some (crappy) voltage readings
I'm thinking most of this data is nonsense because (insert technical reason here: "second transformer needs current draw to turn on etc")
In summary voltages were all over the place under 10v I attempted to stabilize them by putting a 5.5M ohm resistor (then 10 ohm) across the terminals but didnt help.
IMG_20241111_185246560.jpg
As a final hail Mary I jumpered 1-3-5 and 2-4-6 and got more nonsense....so idk :grr
See some junk science tabulated here :
IMG_20241111_191616154.jpg
Values were tough to approximate the readout really wouldn't stay put :loco
And now looking at the picture apparently I have a green-blue-green resistor
:P
I think we will try this again.
Turn the amp off and unplug from power point.
Measure resistance between terminal 1 to 2
Measure resistance between terminal 3 to 4
Measure resistance between terminal 5 to 6.
We need to know if those are the 3 output windings on the output transformer.
You should have very low ohm readings on those terminals.
If the readings are very close to each other then it is likely you have 3x 25V output windings, I have seen that setup on other Dukane amps.
Join terminals 1, 2, 3 together
Join terminals 2, 4, 6 together
Connect an 8 ohm speaker to terminal 1 and terminal 2.
turn on and put a signal into the amp.
Here is the picture you posted last year when you first got that amp, you can clearly see that 2,4,6 are linked and 1,3,5 are linked.
There is also a wire connected as if it is going to a speaker in the picture.
If you right click and save the picture or open in new tab you can see better.
Thanks Boss Man <3) :dbtu:
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.
:grr
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
IMG_20241112_105640268_HDR.jpg
Unfortunately the bottom of the chassis obscures any viewing and surprise looks like an additional transformer
IMG_20241112_105650974.jpg
Bottom of small transformer more Dukane numbers
IMG_20241112_113429234.jpg
Right side
IMG_20241112_105655831_HDR.jpg
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
IMG_20241112_110035881.jpg
But then I saw the orange lense on the front cover
IMG_20241112_110258907_HDR.jpg
But anyhow sir thanks for the assignment will get that for you :tu:
Resistance values obtained
Basically about 2.5 ohm between the bottom three pairs and lower between 7-8
IMG_20241112_123545007.jpg
The jumpered resistance maybe means they are in parallel? Idk
IMG_20241112_123635877.jpg
Anyhow I still need to hook up a speaker and try it jumpered.
:-X
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 :loco
Hey gotta love noobies making things more complicated :dbtu: 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
IMG_20241112_132739397.jpg
It still was extremely erratic and would clip at the drop of a hat IMG_20241112_132930918.jpg
IMG_20241112_133011324.jpg
8|
I am forced to realize that this device is capable of increasing signal. And chopping the end of its peaks off as well.
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 :grr
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 xP
IMG_20241112_114240155.jpg
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 8|
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. :dbtu:
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 :tu:
Ok it was a frustrating evening but it ended somewhat in victory :tu:
I wanted to decipher this enigma machine and play something through it.
IMG_20241116_201522659_HDR.jpg
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
IMG_20241116_201543306_HDR.jpg
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 :tu:
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 :grr
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 :loco
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 :grr
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. IMG_20241116_203416670_HDR.jpg
But they are still bouncing in the red like mad and it's not loud at all....idk
There is yet more Dukane content :loco
I wanted to try a guitar thru it so I used a speaker out of a three way stereo speaker system
IMG_20241118_185702694_HDR.jpg
Or if you prefer
IMG_20241118_185742683.jpg
and ran preamp out of the Peavey Rage 108
(with the Peavey speaker disconnected)
IMG_20241118_185751633.jpg
I played for a while and was taking a break suddenly the speaker started pulsating real bad :grr 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)
Ok it seems the unprovoked appearance of the jackhammer speaker is pulsating bipolar DC.
IMG_20241118_192438891.jpg
IMG_20241118_192439841.jpg
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 . :lmao:
Possibly what is called 'motorboating'?
Often caused by dried up old capacitors no longer doing their job.
Quote from: g1 on November 19, 2024, 08:21:15 PMPossibly what is called 'motorboating'?
Something like this
or like this (@04:18)
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. ;)
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
Quote from: g1 on November 20, 2024, 01:59:29 PMThere 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 ;)
Quote from: g1 on November 19, 2024, 08:21:15 PMPossibly what is called 'motorboating'?
Often caused by dried up old capacitors no longer doing their job.
Oh, my goodness, I just realized that I messed up :duh Being in a rush, I thought it was Saturated asking about it, so I figured I'd point him in the right direction :lmao: Instead, I was teaching one of the big dogs here :lmao:
Apparently, I need a vacation xP
Just now after work I hooked a tuner to the amp and it worked but it had a bad hum.
I tried some resistors and capacitors between the tuner and amp and it didnt help.
Kinda weird because after that I ran my sin wave through it again and it was quiet as a mouse. :grr
Quote from: Miyagi_83 on November 20, 2024, 04:06:24 PMOh, my goodness, I just realized that I messed up :duh Being in a rush, I thought it was Saturated asking about it, so I figured I'd point him in the right direction
The videos are helpful in any case, so you can't go wrong posting useful info.
'Old dog' I could accept. I'm not very big. ;)