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Thread: Silvertone 1484

  1. #1
    Supporting Member bsco's Avatar
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    Silvertone 1484

    Got a Silvertone 1484....with the reverb tank missing.....If you installed a couple of rca plugs on the back panel and hooked up the input and output reverb wiring to these jacks, will this be acceptable?? both in sound quality and safety?? I also noticed that the stand-by switch is connected across the inputs of V7 and V8 which are the two output tubes....Can I open up the connections and install the stand-by switch in the B+ line that feeds the center tap of the output transformer?? Or do I have to open up the B+ supply to all the tubes at the same time??? Or should I just leave it the way it is?? Safety is my BIGGEST concern....
    Cheers,
    Bernie

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  2. #2
    Old Timer olddawg's Avatar
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    1) The reverb element is a piezo type. A standard tank is not compatible without major modifications. The reverb does not work in most of these amps and the consensus is its awful when it works.
    2) The stand by circuit has nothing to do with safety.

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    Quote Originally Posted by olddawg View Post
    2) The stand by circuit has nothing to do with safety.
    Hilarious!

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    Old Timer J M Fahey's Avatar
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    Well, can't speak for others, but if I were making any work inside an amp, I'd much prefer a standby switch opening the +B line, just after the rectifiers, so capacitors discharge through bleeder resistors in a few minutes, than any other configuration, specially a fake standby (mute really).

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    Juan Manuel Fahey

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    Old Timer olddawg's Avatar
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    Quote Originally Posted by Greenmachine View Post
    Hilarious!
    In this amp the standby is just a mute. This amp has a voltage doubler on the B+. Many amps do not even have a standby circuit. Other amps it opens the B+ line. What does the standby circuit have to do with safety? Am I missing something? Probably the best thing you can do for this amp as far a safety is to convert it to 3 wire power cord.

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    Last edited by olddawg; 12-08-2012 at 07:37 AM.

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    Lifetime Member Enzo's Avatar
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    AGreed, the standby switches were not added to amps as a technician safety feature. They are there to mute the amp for the musician's convenience.

    It may add to the safety if we use one, but that is not why it is put into the amp.

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    Education is what you're left with after you have forgotten what you have learned.

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    Whoops, I think I misunderstood and that's why I thought it was funny... I thought that the standby switch in this circuit was connected to a "death cap" like the ground switch in a fender circuit. Hmm, disregard my comment.

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    Senior Member booj's Avatar
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    In some old PV's it is.

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    Supporting Member bsco's Avatar
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    Thanks to everybody for their help and advice. J M, I will do as you suggested...break the B+ directly after the rectifiers...that will be a much better spot for a stand by switch...as far as the connections for the tank go, I'll stick them in anyway but will inform the owner of what to expect..(the original tank is missing and nowhere to be found).......and yes, I had every intention of installing a 3 prong power cord on this unit....I will just have to wait till I get over this damm flu.....

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    I recently modded a 1474 to use a standard reverb tank by adding a reverb transformer and modding the circuit a bit.
    It's not that hard to do if you really want reverb.

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  11. #11
    Supporting Member bsco's Avatar
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    I tried to log into this forum for awhile now but kept getting a message that it was an attack page...glad it is resolved....I found an old reverb tank like the one that used to be there so the owner wants it put in... Now that I am over this H3N2 flu (at least that is what I was told it was)....I will be getting back to this amp...six weeks is a long time to be sick....anyway, I am going to convert to a 3 wire cord and install the stand by switch in the B+ line as suggested....
    Cheers,
    Bernie

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  12. #12
    Supporting Member bsco's Avatar
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    Had a look at the schematic....to connect up a 3 prong cord, just eliminate the ground select switch and the cap tied to it's center pin and ground the third prong to the chassis.....right?? The off/on switch is wired to one side of the line while the fuse in on the other....so I was going to connect the fuse just after the switch....(How about if I also used a DPST switch for the off/on switch).......now for the stand by switch....it was recommended that I break the main B+ supply....there are two lines...one which supplies 480V and another which exits the choke (CH1) and provides 340V. Is it a good idea to also use a DPST switch here as well to control both voltage sources in order to remove and connect the different B+ voltages to the plates of the tubes??? I just want to make sure I don't do anything that I will regret later, so I would want to get some professional opinions here first.... I found another reverb tank from another old amplifier that does not have a reverb transformer......but this amp is a solid state one....will this tank work with the Silvertone?? It is about half as long as the original one that is supposed to be there...and it looks as if one side is grounded while the other side is not.....the side that is grounded is the output??? I don't have the original tank to see.....anyway if anybody has any knowledge that they are willing to share with me it is much appreciated.........
    Cheers,
    Bernie

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  13. #13
    Old Timer olddawg's Avatar
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    Quote Originally Posted by bsco View Post
    Had a look at the schematic....to connect up a 3 prong cord, just eliminate the ground select switch and the cap tied to it's center pin and ground the third prong to the chassis.....right?? The off/on switch is wired to one side of the line while the fuse in on the other....so I was going to connect the fuse just after the switch....(How about if I also used a DPST switch for the off/on switch).......now for the stand by switch....it was recommended that I break the main B+ supply....there are two lines...one which supplies 480V and another which exits the choke (CH1) and provides 340V. Is it a good idea to also use a DPST switch here as well to control both voltage sources in order to remove and connect the different B+ voltages to the plates of the tubes??? I just want to make sure I don't do anything that I will regret later, so I would want to get some professional opinions here first.... I found another reverb tank from another old amplifier that does not have a reverb transformer......but this amp is a solid state one....will this tank work with the Silvertone?? It is about half as long as the original one that is supposed to be there...and it looks as if one side is grounded while the other side is not.....the side that is grounded is the output??? I don't have the original tank to see.....anyway if anybody has any knowledge that they are willing to share with me it is much appreciated.........
    Cheers,
    Bernie
    Honestly, I would leave the standby alone. What will you actually accomplish by changing it? The original reverb module has 2 piezo crystals. If your replacement is not a piezo type it will not be a drop in replacement. If you can find a Silvertone or Danelectro module, even not working they can be rebuilt. I think Enzo posted on how to do it a while back. Just do a search. Still though, most people believe the original reverb is awful anyway. You might consider putting the amp in good working order and just using a reverb pedal.

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  14. #14
    Supporting Member bsco's Avatar
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    OK then.... Sounds like that is the way to go....Thanks very much for your reply..The replacement reverb unit is not piezo type..it has two tiny transformers but the amp does not have a reverb transformer...anyway I'll do what you have suggested.....
    Cheers,
    Bernie

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  15. #15
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    I added a Fender reverb circuit to my brother's Silvertone 1484 about 5 years ago. I completely re-routed the whole preamp arrangement as I was doing other things at the same time. I also added the Fender reverb transformer. The reverb mod works fine, but to make it work I built a new head and mounted the Fender reverb pan above the amp chassis on a metal pan. It was a lot of work but it is worth it as the amp sounds much better now. We left the standby as is...why change it....it works fine and with receiving tubes there is no technical need for a standby...its only a stage mute thing really...and the stock setup works fine for that purpose by shorting the grid inputs together on the power tubes. One thing that is helpful in these amps is to install a voltage doubler and an adjustable bias pot in the bias supply as they run a bit hot stock. If you greatly increase the gain in the amp, it will begin to hum a lot....not much can be done about that due to the power transformer location.

    Greg

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  16. #16
    Supporting Member bsco's Avatar
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    Thanks soundmasterg.... The owner is going to use an external reverb...I installed the 3 prong power cord and I left the stand by switch alone..........about the hum....I placed the chassis on a metal surface( the back panel from a Marshall head) and all my hum problems went away...Have a bad volume pot in the first channel...will replace that tomorrow...will line the inside of the cabinet with a metal foil so the amp will be shielded when the chassis is re-installed in the cabinet...(had to do that as well to a Fender 75 recently).The foil that was inside the cabinet has pretty much disappeared... Once again, thanks for the help..
    Cheers,
    Bernie

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