Psst... Ready to join TalkBass and start posting, make new friends, sell your gear, and more?  Register your free account in 30 seconds.

Old Sunn amp volume trouble

Discussion in 'Amps and Cabs [BG]' started by protoz, Jan 26, 2005.


  1. protoz

    protoz

    Nov 30, 2000
    Iowa
    I finally got my Sunn Colliseum 300 (300 on 2Ohm) in the mail yesterday and took it to practice to break in right. I plugged it into my 4Ohm 500watt 1x15 which gives me 200watts of power.

    I had to crank the gain to max and the master almost to full (about 3 O'clock) after putting most of the eq at 12 O'clock or higher to hear myself over an old Vox Buckingham 2x10 setup. I have roughly double the wattage but still had difficulty cutting through.

    I noticed that the pots were pretty scratchy, especially the volume knob so I am wondering if I am not getting all the volume I should be due to worn out pots.

    The tone is buttery rich and I have heard this amp is supposed to be very loud, so I want to keep using this head as much as possible, I'll add a poweramp if I need to!

    Thanks
     
  2. NCorder

    NCorder Smoke-free since 4/3/05

    Dec 26, 2002
    Dayton, OH
    FWIW, I have an old Sunn Concert Bass amp which (I think) puts out less watts than the Colliseum models. It pushes my Ampeg 2x15 cab without breaking a sweat.
    Definately sounds like somethings wrong. I would take it to a reputable repair shop and have it given a onceover. If its just a bad pot, they should be able to fix 'er right up for cheap.
    Good luck!
     
  3. protoz

    protoz

    Nov 30, 2000
    Iowa
    Yea concert bass amps are lower wattage. I thought I was just going crazy that a 65-100watt SS guitar amp was out driving a 200watt 1x15 that ususally shakes the place with my Hartke 5000.

    It is a good thing I talked to my tech before it arrived and he said he could take a look at it and give it a good cleaning, but repairs would be difficult with out schematics
    (which I can find all but the preamp)
     
  4. I have an old Concert Bass amp myself...it kept cutting out/losing power. Basically, there's a couple dozen connectors inside where wires push onto pins on the circuit boards. These connections were very oxidized, most likely causing the volume losses. I soldered each one of them, and improved the situation. (I still have noisy pots, and the amp needs a cap job, but it's pretty low on my priority list....)
     
  5. I've had this problem with several vintage amps.your capacitors could be nearing the end of their days and are possibly leaking, definitely see if you only need a service but it could be you need some parts...
     
  6. protoz

    protoz

    Nov 30, 2000
    Iowa
    [Update]

    After playing with the amp some more I found out how to get the proper volume out of it so I am getting MUCH better tone out of it than my Hartke and near the same volumes as well. Possible user stupidity or I had to break it back in...one of the two.

    I found out that I get some notes to get the speaker to make a crackle sound. The pots no longer crackle when adjusting them after a little cleaning...it was very dirty that poor thing.

    Would this crackling be from the input/output jacks or something internal?

    I was thinking of having the caps looked at as well since I was told a good rule of thumb is to replace them every 10 years or so.

    Any other suggestions from you vintage amp guys to help me bring my amp back to its former glory?

    On a side note, does anyone know if there was a side hole on these Coliseum 300s? I see 2 holes on the right side that would be perfect for a side handle

    here is a link to some pictures I took of it. I haven't cleaned all of it yet but it's almost all the way cleaned.
    http://givinguponyou.com/brutalrepublic/images/coliseum/
     
  7. NCorder

    NCorder Smoke-free since 4/3/05

    Dec 26, 2002
    Dayton, OH
    I'd like to see your pics, but the link says "webpage coming soon"... error?
     
  8. protoz

    protoz

    Nov 30, 2000
    Iowa
    Crap, my wemaster must have forgotten to pay :S
     
  9. Old amps (amps older than 30 or 40 years old) should probably have their electrolytic capacitors replaced, or at least checked by somebody that has an ESR meter...a dried out cap can still measure good as far as capacitance, the real test is what the ESR is.

    I've read newer caps have a longer useable life, so I don't think the replacement caps will need replacing for many many years. I've tested 25 year old caps on my ESR meter and they've still measured good....unfortunately, my ESR meter is low voltage, I wish I had a high-voltage ESR meter.
     
  10. protoz

    protoz

    Nov 30, 2000
    Iowa
    Link is back up for the pictures

    I'll have to ask the guys at my music center about an ESR meter...
     
  11. I doubt they'll know what you're talking about. There's a lot of techs that don't even know what ESR is, much less the existence of meters that can check it. A scope and a sig gen can also check ESR, but you need to make a setup to do it....
     
  12. protoz

    protoz

    Nov 30, 2000
    Iowa
    Well I'll see what I can do. Caps will be redone more or less as a precaution/piece-of-mind I think.

    Sever is back down, think there is some maintainence going on today, maybe tomorrow it will be good to go.
     
  13. R Briere

    R Briere Bass-ically Yours

     
  14. protoz

    protoz

    Nov 30, 2000
    Iowa
    I actually don't really know. I just played with the eq a bit and cleaned the dirty pots. Still got that crackle now and again though.

    Don't you run the Sunn forum on dangpow?
     
  15. R Briere

    R Briere Bass-ically Yours

    Greetings again Protoz,

    Nope, I don't run it and I SHOULD be spending more time there again. Thanks for the inspirational reminder. I do have a fair amount of information about Sunn on my personal site though. Check out the "Sunn Shack" pages at:
    http://www.richbriere.com
     
  16. protoz

    protoz

    Nov 30, 2000
    Iowa
    I knew you ran one of my resource sites :)

    Great info you have on there, only if you had more info on the Coliseum 300. ;)
     
  17. R Briere

    R Briere Bass-ically Yours

    I'll see if I can dig some up for you. :^>)
     
  18. protoz

    protoz

    Nov 30, 2000
    Iowa
    That would be awesome, I have the manual already I just have no clue when they came out.
     
  19. protoz

    protoz

    Nov 30, 2000
    Iowa
    I just got my Sunn back from the shop today and he cleaned the pots, fixed the handle, changed the cord to a grounded plug.

    Great, that's what I asked for.

    But he didn't fix the main problem I have with it: At certain frequencies I get a crackle. Easily reproduced by plucking the 5th fret on the E while in standard it goes crazy.

    No amount of tweaking can get it to go away entirely. I dropped the EQ to flat, Overload just loud enough to hear it and I could still get it to go off.

    Does anyone have any ideas on what this could be? He replaced a bad input jack but I have a feeling it may be the speaker jacks (both will make the crackle) or something a little more serious.
     
  20. Passinwind

    Passinwind I Know Nothing Supporting Member

    Did he replace the power supply filter caps? That still sounds like the most likely source of your problem.