Question for 1472/1482 Silvertone amp owners

[slidincharlie (Carlo P)]

Although the 1472 and 1482 Silvertone amps look almost the same, their schematics show some dramatic differences in the AC voltage of the power tranny secondary, and hence in all the downstream DC voltages: these are generally much higher in the 1482 model.
There is another difference that I have noted: the 1472 schematic calls for a 4 ohm (actually 3.2 ohm) speaker, while the 1482 schematic calls for an 8 ohm speaker. Is there any 1472 owner out there who can confirm this? I have a 1472 on my bench that needs a new speaker: the old one is blown and I want to be sure to put the right speaker in there.
--Carlo

[capnjuan]

Hi Carlo: Yes, the voltages are different however the 1472 schematic http://www.freeinfosociety.com/elect...ertone1472.pdf on the far right indicates: "VC [voice coil] 3.2 ohms" The OT only has 4 ohm taps.

The schematic for the 1482 http://www.freeinfosociety.com/elect...ertone1482.pdf is drawn showing a speaker connected to the 4 ohm taps. This amp can take either a 4 or 8 ohm speaker.

You can connect an 8 ohm speaker load however the amp circuit will work twice as hard to do the same amount of work. I think you should only consider a 4 ohm speaker for your 1472.

Hope your pots came out ok on your SF. capnjuan

[slidincharlie (Carlo P)]

Hi cj!
The 1472 schematic shows only one tap off the OT, but it does have two taps actually... check my thread on the TDPRI and the Hoffman forums.
And yes, my Guild SF works fine now

[capnjuan]

Hi Carlo: saw the thread in Hoffman, didn't realize that your 1472 OT has 4 and 8 ohm taps. I wonder if OT is original to the unit? Maybe the 'dead' speaker was the 'wrong' speaker or tied to the wrong taps?

The 1472 circuit operates at lower power and I think the circuit would be happier if it was operating into a 4 ohm and not an 8 ohm load; more like a Champ. If the OT has 3 wires out, are you able to identify which is the common? If yes, a 4 ohm speaker would tie there and to the tap next to it. cj

[pluckwire4sound]

Hi, Sorry if I'm breaking thread protocol...I'm new to the site and it's a little confusing to me. I'm trying to find out if the silvertone 1472 and danelectro 273 share the same schematic. I'm asking because I was searching for a danelectro 273 schematic and I stumbled onto a thread on this site that reads "silvertone 1472/danelectro 273". Other than on this thread, I can't find any other reference to the two amps being virtually the same. Thanks for any info...!

JC

[Enzo]

Hi, welcome.

No, you are not breaking any protocols, but tacking on at the end of a thread that has been dead for six years is probably not the most efficient. Threads don't cost anything, just start a new one.

In case you don;t have it, here is the Silvertone:
http://bmamps.com/Schematics/Silvert...ertone1472.pdf

Sears didn;t make the amps, they contracted that out, and Danelectro made a lot of them for Sears, so I have no trouble believing they might be the same. If you have the amp, look at the Silvertone drawing and see if it matches up. Even if ther are some value differences here and there, if they are mostly the same, that should be good enough. AMp makers used to change circuits all the time, and only some of that got documented.

[pluckwire4sound]

Hi, welcome.

No, you are not breaking any protocols, but tacking on at the end of a thread that has been dead for six years is probably not the most efficient. Threads don't cost anything, just start a new one.

In case you don;t have it, here is the Silvertone:
http://bmamps.com/Schematics/Silvert...ertone1472.pdf

Sears didn;t make the amps, they contracted that out, and Danelectro made a lot of them for Sears, so I have no trouble believing they might be the same. If you have the amp, look at the Silvertone drawing and see if it matches up. Even if ther are some value differences here and there, if they are mostly the same, that should be good enough. AMp makers used to change circuits all the time, and only some of that got documented.

I'm new to the site, so after I signed up it seemed I was left at a page where there was (apparently) no window to start a thread, or my old eyes couldn't adjust..... . Anyway, thanks for the pdf. and I'll give it to my repair guy. Thanks much! Have a good weekend............!

[Uncle Joe]

Hi, welcome.

No, you are not breaking any protocols, but tacking on at the end of a thread that has been dead for six years is probably not the most efficient. Threads don't cost anything, just start a new one.

In case you don;t have it, here is the Silvertone:
http://bmamps.com/Schematics/Silvert...ertone1472.pdf

Sears didn;t make the amps, they contracted that out, and Danelectro made a lot of them for Sears, so I have no trouble believing they might be the same. If you have the amp, look at the Silvertone drawing and see if it matches up. Even if ther are some value differences here and there, if they are mostly the same, that should be good enough. AMp makers used to change circuits all the time, and only some of that got documented.

I'm glad this thread was revived... It led me to some good info. Enzo, you're right... there is probably a lot of undocumented variation in amp circuits, especially anything that was made for Sears. I noticed that your 1472 schematic is an original rather than re-drawn... the 1482 schematics posted here and elsewhere are re-drawn. My 1482 is different from the schematics posted here, and from the schematic I ordered from Sam's Photofacts many years ago... it has an extra RC filter that lowers the B+ voltage to the preamp stage (like the 1472), but it uses a 56K resistor instead of 100K... these additional parts are not shown on my schematic or other 1482 schematics I've seen. My amp also has an untapped OT secondary (like the 1472) and a 3.2 ohm speaker - which matches my schematic, but the 1482 schematics posted here show a tapped secondary.

In my 1482, I replaced the PS filter caps long ago with a 2 section can from another amp and a couple of discrete caps I happened to have. I replaced the rectifier tube with silicon diodes, removed the tremolo circuit (wish I hadn't now); removed the instrument preamp circuit in favor of a single input using the mic channel; added a cathode resistor bypass cap in the preamp stage, changed values on some of the coupling caps, and installed a 3 prong power cord for safety. I also replaced the original speaker with a "Pyle Driver" (MH1229) that I picked up from a music store years ago. I don't know what the impedance rating is on that speaker, but it works... I found specs for the speaker, but impedance was not listed.

My 1482 sounds pretty good, but I have been feeling the urge to tweak it some more... Opened it up the other day to verify the current situation... Cleaned up the ground connections and removed the "death cap" (I only recently learned that it is a potential hazard and not needed with a 3 wire AC input.)
After some thought, I would like to make a few more changes...
- Add a standby switch, or restore the VT rectifier circuit... the tubes are probably taking a beating from the solid state diodes before the heaters warm up...
- Restore the tremolo circuit.
- Rebuild the instrument input preamp for a cleaner sound, get more gain from the mic preamp, and figure out a way to set up with foot-switchable clean/overdrive channels.
- Add reverb (maybe too complicated).
- Build, salvage, or buy a nice, solid cabinet for it.
I've never liked the chassis layout... power switch, pilot light, and input jacks in the back, with controls on the front/side... it's just dumb. I would love to rebuild the whole thing with input jacks, switch, pilot light, and controls on the front/top, and a nice, solid cabinet.

I would appreciate some feedback on these ideas, especially changing the chassis layout, better cabinet, and foot-switch clean/overdrive channels. It would be easier to buy a different amp, but this one has been with me a long time, and I like to experiment.