Sivertone type amp...mids tweaks

[tacoma98]

Hello everybody. I am not an seasoned amp builder.PLEASE keep it VERY simple when replying. Thanks. I have a Silvertone amp-similar to a champ.6 watts or so single ended class A . (1) 5ur4(1)12ax7(1) 6V6. I guess I could plug a 5Y3 into it to loosen it up a bit..It has a .0047 orange drop on the tone pot. (2) Jupitor(mustard type) .022 coupling caps. A few mods were made by a tech but is basically a small Silvertone with a Tweed Princeton tone stack. The amp is great for r&r type tone but I would like to get that Wide Panel Princeton (heavy mids,loose bottom) honk a little more pronounced. Got any ideas? Please explain how to do both : Mid increase and looser bottom- I want to try either or both mods and see if the two sound good or just one. Also, like I mentioned I have a Orange Drop in the tone control- would a diff type of cap on the tone pot smooth the highs out? : SilverMica, Mustard Cap or Ceramic? What is the SilverMica(pf) value for the following: .022uf........1uf.......and .0047uf? Thanks for all of your time and help with this "green horn's" questions. Note: I do not know what Phase inverters are, 1st stage, grids etc.....try to keep it simple with caps/resistors etc.....if this goal is possible with cap or resistor swaps. Thanks

[Regis]

Hello everybody. I am not an seasoned amp builder.PLEASE keep it VERY simple when replying. Thanks. I have a Silvertone amp-similar to a champ.6 watts or so single ended class. (1) 5ur4(1)12ax7(1) 6V6. It has a .0047 orange drop on the tone pot. (2) Jupitor .022 coupling caps. A few mods were made by a tech but is basically a small Silvertone with a Tweed Princeton tone stack. The amp is great for r&r type tone but I would like to get that Wide Panel Princeton (heavy mids,loose bottom) honk a little more pronounced. Got any ideas? Please explain how to do both : Mid increase and looser bottom- I want to try either or both mods and see if the two sound good or just one. Also, like I mentioned I have a Orange Drop in the tone control- would a diff type of cap on the tone pot smooth the highs out? : SilverMica, Mustard Cap or Ceramic? What is the SilerMica(pf) value for the following: .022uf........1uf.......and .0047uf? Thanks for all of your time and help with this "green horn's" questions. Note: I do not know what Phase inverters are, 1st stage, grids etc.....try to keep it simple with caps/resistors etc.....if this goal is possible with cap or resistor swaps. Thanks

It would help if you could give a model number or schematic.

[tacoma98]

Silvertone 1481

Hello Regis- it's a Sears Silvertone 1481. However, it has been tweaked a bit and has a Tweed Princeton tone stack.

[tubeswell]

I would like to get that Wide Panel Princeton (heavy mids,loose bottom) honk a little more pronounced. Got any ideas?

The amp's tone is a lot more than just the product of the tone stack. However for experimenting, you do have the right sort of tubes for the 5D2 wide panel princeton. So check that schematic out. (note that the first stage is grid biased - this is not terribly reliable and is not done in commercial amps these days). Also unless everything else about the 5D2 is very similar, i.e. the rest of the circuit, including PT, OT and speaker, your amp will come out sounding different

http://www.thevintagesound.com/ffg/s..._5d2_schem.gif

Please explain how to do both : Mid increase and looser bottom- I want to try either or both mods and see if the two sound good or just one.

You'll have to do a bit of experimenting here. The bottom of this page has useful tips on tweaking gain stages. I suggest making your tweaks one at a time

Tube Terminology for Dummies

Also, like I mentioned I have a Orange Drop in the tone control- would a diff type of cap on the tone pot smooth the highs out? : SilverMica, Mustard Cap or Ceramic?

Cap types don't change the tone as much as cap values do

What is the SilverMica(pf) value for the following: .022uf........1uf.......and .0047uf? Thanks

To convert uF to nF multiply by 1,000. To covert nF to pF multiply by 1,000. (So to convert uF to pF, you have to multiply by 1,000,000). You can find mica caps in 4700pF (although they are not so common) but I doubt you will find mica caps in 22,000pF let alone 1,000,000pF (however if you do please let me know). So stick with film caps (orange drops, mustard caps etc) for the bigger values. Nothing wrong with mustard caps (or orange drops either).

[Regis]

You can't put a 5Y3 in a 1481, the 5Y3 is an 8 pin rectifier and the 1481 uses a 7 pin 6X4. You'd have to replace the power transformer to do it.

The "Tone Stack" in both the Fenders and the Silvertone is just a pot and a cap, albeit a little different. Personally I don't even like tone controls in small amps like this, all they are is a treble cut and these kinds of amps never have enough treble for me.

I would try changing the cathode resistor on the 12AX7 from a 2.2k to a 1k, and add a 25uf bypass cap. Also put a 25uf bypass cap on the 6V6 cathode resistor and call it a day.

Tubeswell is correct, stay away from that cathode biased input, what you have in the Silvertone now is fine, or wire it like a 5E1 Champ.

[tubeswell]

Oops! I thought he said he had a 5Y3 in there already - I missed that bit about '5UR4'. What is a 5UR4 anyway? I can find 5R4 and 5U4G in my stash, but never heard of a 5UR4 before. I presume its a either 5V rectifier tube of some description, or a misquote?

[Regis]

Oops! I thought he said he had a 5Y3 in there already - I missed that bit about '5UR4'. What is a 5UR4 anyway? I can find 5R4 and 5U4G in my stash, but never heard of a 5UR4 before. I presume its a either 5V rectifier tube of some description, or a misquote?

The closest I could find is the GZ32 of which the 5VR4 is compatible. There were no Silvertone amps that used this tube. Danelectro, which built the Silvertone amps in the sixties, used a 6X4 or 6X5 rectifier tube for their single ended amps. The 1481 does not have a 5v tap for any tube that requires it.

So, I don't know what the heck you've got there.

[tacoma98]

5Y3 tube in 1481?

Yes I put the amp/components into a diff chassis. I replaced the PT with a Princeton and swapped the 6X4 for an 8 pin socket to have the option of using a 5U4G (which is close to a 6X4 or a 5Y3 for more sag. I was just wondering how to get more mids from this amp. I have .022uf coupling caps in there currently- got any ideas with values of coupling caps or any other caps/res? Thanks..................sorry correction: the rec is a 5U4G GElectric

[Sweetfinger]

Speaker type/size is going to make a surprising difference in this amp.

[tacoma98]

speaker size?

Thanks for the reply. I am running 2X10 alnico's. I have heard 57 Tweed Pro's and other vintage amps with 15" spks and they have plenty of mids.Why would size of spk matter? Does a 6 or 8" spk give up more mids? Thanks for the help

[Sweetfinger]

not just size, but type of cone makes a big difference. Magnet size, dust cover, everything contributes. What Alnico 10's are you using?

[tacoma98]

2009 Jensen PR10's Alnico magnets. Thanks for the help with this!

[falling_frog]

Tone Stack change

I am an engineering student and I actually changed the tone knob on my 1481 into a variable mid scoop instead of a high cut, I can send you a schematic if you're feeling ambitious. I put the mid scoop frequency in the same spot that fender amps put it.

Sean