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New amp day! Silvertone 1481

Started by galaxiex, May 31, 2017, 09:19:28 PM

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galaxiex

New Amp Day!

Look what landed on my doorstep today!

Thought I'd put this here since its a tube amp.  :)

Found this on Reverb for a good price.
It sounds great considering the speaker cone is a little soft. Farts a bit on low notes.
Speaker looks original, as do the tubes.
The 6X4 rectifier is a JAN Phillips, not sure if that would be original.

Is that really how they hooked up the speaker back then?
Right off the O/T winding?


If it ain't broke I'll fix it until it is.

galaxiex

If it ain't broke I'll fix it until it is.

J M Fahey

Quote from: galaxiex on May 31, 2017, 09:19:28 PM
Thought I'd put this here since its a tube amp.  :)
What makes you think that?  :o
Last time I checked, site name said "SS"  :o

phatt

Well it is under  *Tubes and Hybrids*  ;)
Phil.

galaxiex


What makes you think that?  :o
Last time I checked, site name said "SS"  :o
[/quote]

Quote from: phatt on June 02, 2017, 08:44:52 AM
Well it is under  *Tubes and Hybrids*  ;)
Phil.

Ummm, yes this is the area of the forum for tube amps.

I guess this forum doesn't get much traffic from tube amp folks.

Oh well, mods please feel free to move this thread as you see fit.
I guess it would have been better in players corner.
If it ain't broke I'll fix it until it is.

teemuk

QuoteIs that really how they hooked up the speaker back then?
Right off the O/T winding?

Speaker load is the secondary side circuit so how else should they make the connection? Since I see no features such as extension speaker jacks or alike isn't that the shortest and most logical method to connect the speaker?

Theoretically there could be a speaker out jack and a plug in the speaker wires ...but why? Now its solid connection to load and additionally they manmaged to make the cheapie model even cheaper.

IMO, this one isn't even an oddity. You probably haven't seen those vintage amps yet that have their tiny, tiny OTs riveted right to the speaker frames...?

Enzo

teemu, I could be wrong, but I think what he found odd was the enamel winding wires from the transformer soldered directly to the speaker.   As opposed to the winding wires going to a terminal strip and then the speaker wires connected there.  So the physical arrangement rather than the electrical aspect.  At least that is how I read it.


Actually, on old amps like that, it was not uncommon to see the small output transformer itself mounted right on the speaker frame.  Then the (typically) blue and red wires of the primary went back to the chassis.

Like this old Gibson (Jensen speaker in Gibson amp):

phatt

Hey chaps,,, if you go back far enough, before magnet materials became economical speakers had a big Electromagnet wrapped around the voice coil of the speaker.
IIRC simply called Electromagnetic speakers which came with a Field Coil which created the magnetic field for the VC.

I think the field coils may have been wired out of phase to reduce hum,,,, so maybe humbucking was understood long before the idea was used in PU's  8)
Phil.

a couple of links showing the idea;
https://www.youtube.com/watch?v=Pq64-ayRyfs

https://www.youtube.com/watch?v=rHhSqEMyzIs

galaxiex

#8
Quoteteemu, I could be wrong, but I think what he found odd was the enamel winding wires from the transformer soldered directly to the speaker.   As opposed to the winding wires going to a terminal strip and then the speaker wires connected there.  So the physical arrangement rather than the electrical aspect.  At least that is how I read it.

Yes, this is what I meant, the physical arrangement I had not seen before.
It makes sense to do that in a budget guitar amp where they are pinching pennys.
The question was sort of rhetorical.
Sorry, I should ask questions where I actually expect an answer, rather than "thinking out loud".

For the record, I am familiar with field coil speakers,
well... familiar in the sense that I had on old "portable" record player (my Dads) long ago that I took apart to "see how it worked".
(ahh, curious youth)
It had field coil speakers.

I stripped it down to attempt to build a rather crude guitar amp.
My Dad didn't mind, he had bought a fancy "new" stereo music system. ;) 

I knew enough to know that the guitar input would have to be hooked up where the needle cartridge was connected.
It didn't sound very good....   :lmao:
If it ain't broke I'll fix it until it is.

Enzo

I doubt field coils were wired "out of phase" because they ran on DC.. If you have two coils wired one reverse the other, they form opposing magnetic fields, a weak result.

In my example, the field coil is a separate issue from the speaker frame mounted transformer.

g1

  Though not hum-bucking, the field coil does often also serve as a choke for the power supply.  So it is dual purpose in that sense.
However, I do vaguely recall some speakers that did in fact have an extra hum-bucking coil?

joecool85

Quote from: galaxiex on June 02, 2017, 08:16:27 PM
Ummm, yes this is the area of the forum for tube amps.

I guess this forum doesn't get much traffic from tube amp folks.

Oh well, mods please feel free to move this thread as you see fit.
I guess it would have been better in players corner.

You are correct, this is where this post belongs - no worries!  :tu:

Also, neat amp!
Life is what you make it.
Still rockin' the Dean Markley K-20X
thatraymond.com

galaxiex

If it ain't broke I'll fix it until it is.

galaxiex

Well time to start working on this....

First look inside the chassis shows someone replaced the 2 wire power cord..... with a newer 2 wire power cord....  ::)

So I installed a 3 wire power cord and clipped the death cap.
If it ain't broke I'll fix it until it is.

galaxiex

Arrrgh!

After installing the 3 wire cord and a speaker jack....

The amp no longer works!  :grr

Quick inspection reveals the O/T primary is now open! Rats!

Seems this is common on these amps (google search) so I ordered a Hammond replacement O/T for a Fender Champ.

Mercury Magnetics has a Silvertone 1481 O/T listed, but the price is triple the Hammond.

I'm sure the Hammond will be just fine....
If it ain't broke I'll fix it until it is.