Difference between Blackface & Silverface Champ

Discussion in 'Amps and Cabs' started by Roodboy, Sep 21, 2006.

  1. Roodboy

    Roodboy Member

    Joined:
    Jun 1, 2004
    Messages:
    1,424
    Location:
    Long Island
    Can anyone fill me in on the differences between the two? I think the dripface silvers are the same as the blackfaces.
    I'm looking for a Jamesgang/Joe Walsh Funk 49 vibe.
    Thanks
     
  2. QuickDraw

    QuickDraw Member

    Joined:
    Mar 6, 2005
    Messages:
    791
    Location:
    St. Paul, MN
    as far as i know the faceplate and grille cloth are different and that's it on the champs
     
  3. Gas-man

    Gas-man Fever In The Funkhouse Silver Supporting Member

    Joined:
    Feb 28, 2006
    Messages:
    16,757
    I've had both and to my ears the blackface had smoother OD than the silver.

    Silver was somewhat buzzy.
     
  4. utterhack

    utterhack Member

    Joined:
    Feb 5, 2006
    Messages:
    2,814
    Location:
    SF: Mission
    Since there were no circuit changes, I'd chalk that up more to the differences between two old amps than the difference between blackface and silverface champs.
     
  5. TopJimmy5150

    TopJimmy5150 Member

    Joined:
    Aug 8, 2005
    Messages:
    271
    Post '72 SF Champs have plywood construction. I think there were some changes in the OT, but nothing terrible. I'm sure at one point they probably eliminated cloth wires and other running changes that effected the whole line, but in general the Champs/Vibro Champs didn't screwed around with too much by the CBS penny-pinchers. I have a '76 that's not going anywhere. :D
     
  6. jonny guitar

    jonny guitar Member

    Joined:
    Apr 20, 2005
    Messages:
    325
    Buzzy??? Wow, my SF champ could be decribes in many ways but I would never call it buzzy in the least.

    As to the original posters quest for james gang...decent boost pedal and sf champ will just totally nail it!!
     
  7. Dana-L

    Dana-L Member

    Joined:
    Feb 27, 2006
    Messages:
    468
    Location:
    Outer Portlandia
    From what I can tell from the schematics, in the Silverface era Fender changed the specifications on the power transformer so they provide higher voltages. Otherwise, the schematics are identical. The difference is that the potential nearest the rectifier is listed as 420V for Silverface Champs versus 360V for the Blackface versions.

    On the schematics, the part numbers for the power transformers remain unchanged (125P1B) but the listed voltages have changed.

    Do any amp experts have any insight on this?

    Specifically, would adding a dropping resistor between the power transformer and first PS filter cap be all it takes to convert a Silverface Champ to Blackface specifications?

    Also, on my own Silverface Champ, I've also noticed that the first power filter cap (inside the silver aluminum cap can) is actually 40uF whereas the schematic says it should be only 20uF.

    Very best regards,

    -Dana
     
  8. marscottm

    marscottm Member

    Joined:
    Feb 12, 2006
    Messages:
    345
    Location:
    sunny florida
    it was my understanding that PT changes only affected the larger amps (i.e. bigger than a Deluxe). I doubt there's any significant difference between a BF and SF champ PT

    Scott
     
  9. billyguitar

    billyguitar Member

    Joined:
    Aug 30, 2005
    Messages:
    3,411
    Location:
    Kansas City
    I had read Funk 49 was an Esquire or Tele and a Deluxe. Not a fan of champs myself even though I have two tweeds, a blackface and a Bronco which is a vibrochamp. I think other little amps sound better, for the most part. Gibsons, Kays, Silvertones etc.. Just my opinion, not dissing anyone's taste in amps. Afterall, if we all liked the same stuff we'd all sound the same!
     
  10. drbob1

    drbob1 Supporting Member

    Joined:
    Aug 9, 2004
    Messages:
    12,171
    I've owned 5 or so Vibrochamps and champs, no difference at all in sound. The best sounding one I have is an early 70s SF.
     
  11. Dana-L

    Dana-L Member

    Joined:
    Feb 27, 2006
    Messages:
    468
    Location:
    Outer Portlandia
    Looking even more closely at the Blackface and Silverface schematics, the PT voltages feeding the 5Y3 rectifier increased from 320V AC (Blackface) to 365V AC (Silverface).

    The only change I see is the increase in power supply voltages; Other than a three prong cord, a thermal protector, and a 0.047 uF cap (all on the input side of the PT), every single resistor and capacitor value on the schematic is the same for the Blackface and Silverface Champ amps.

    What else could cause the increase in voltage other than changed specifications for the power transformer?

    Best,

    -Dana
     
  12. marshallnoise

    marshallnoise Member

    Joined:
    Oct 1, 2006
    Messages:
    182
    Location:
    California
    I love my SF Champ. It is a 73 and its blowing fuses. But I think its because I am running it through an 8 ohm load. Any guys think that might do it?
     
  13. Dana-L

    Dana-L Member

    Joined:
    Feb 27, 2006
    Messages:
    468
    Location:
    Outer Portlandia
    I'm an SF Champ lover, too. Mine's an '80 or '81 that I got new as a Christmas gift from my mom and dad.

    I don't know if running an 8 Ohm load would cause fuses to fail but it will eventually kill your output transformer.

    What I did was build some cables and a small junction box (with parts from Radio Shack) that allows me to connect a Jensen P10R and P15R (each is rated at 8 Ohms) in parallel (for a net 4 Ohm load) to the Champ's 3.2 Ohm output (a safe impedance mismatch).

    The result is very, very good (to put it mildly)!

    -Dana
     
  14. marshallnoise

    marshallnoise Member

    Joined:
    Oct 1, 2006
    Messages:
    182
    Location:
    California
    .

    Schematic!!!!! Puhlease!!!!!!!!!!
     
  15. Texsunburst59

    Texsunburst59 Member

    Joined:
    Mar 4, 2005
    Messages:
    2,308
    Location:
    Texas Gulf Coast
  16. Dana-L

    Dana-L Member

    Joined:
    Feb 27, 2006
    Messages:
    468
    Location:
    Outer Portlandia
  17. Dana-L

    Dana-L Member

    Joined:
    Feb 27, 2006
    Messages:
    468
    Location:
    Outer Portlandia
    I don't have a schematic for the junction box pictured below - it's just three 1/4 phono jacks wired so all the tips are connected to one another and all the sleeves are connected to one another using short pieces of stranded wire.

    The twisted wires have a male RCA plug on the end that connects to the Champ and a standard 1/4" phone plug that goes into the black junction box. Each of the remaining jacks are used to connect to the 8 Ohm speakers.

    I got the box and jacks at Radio Shack. The RCA and phone plug are made by Neutrik and came from Parts Express (http://www.partsexpress.com). You could get similar items at Radio shack.

    Building these was good soldering practice for me.

    -Dana

    [​IMG]
     
  18. marshallnoise

    marshallnoise Member

    Joined:
    Oct 1, 2006
    Messages:
    182
    Location:
    California
    Man that is such a great idea. I want to do that but since all I am running my Champ through is a Marshall 1936 2X12 and that sorry cab only has 16 ohm speakers. I think I will just build a nice 1X12 extension cab for it. I already converted the RCA style jack to a regular 1/4" jack. I am sitting and looking at this thing and good gawd it is simple. Has HUGE resistors in it. I just hope all of them haven't left spec.

    Thanks for posting that though, it gives me other ideas...
     
  19. Wakarusa

    Wakarusa Member

    Joined:
    May 7, 2004
    Messages:
    1,478
    Location:
    San Jose, CA
    One very slight difference between blackface and silverface is the 330pF cap between power tube grid and ground on the silverface. In the real world I've seen this cap installed grid-cathode, plate to cathode, and in values ranging from 330pF to 2200pF. The earliest Champ I've seen it in is a '69 drip-edge.

    Also (as John Philips has posted repeatedly) as the wall voltage crept up and the PT stayed the same, B+ crept up too -- making it so the 470 cathode resistor on the power tube often doesn't bias the tube correctly.
     
  20. Dana-L

    Dana-L Member

    Joined:
    Feb 27, 2006
    Messages:
    468
    Location:
    Outer Portlandia
    Nice catch on the 330pF cap! I missed that one.

    Regarding wall voltage, what was the typical value in the early 1960's?

    Do you think there is any merit to the idea of installing a dropping resistor between the rectifier and the first filter cap to reduce B+?

    Finally, what value of cathode bias resistor do you prefer (assuming the higher B+ of the Silverface units)?

    Thanks & best regards,

    -Dana
     

Share This Page