Another Hartke Thread!

Discussion in 'Amps and Cabs [BG]' started by Funk On Crack, Dec 14, 2005.

  1. Ok, I did a search but my problem is a little different.

    My 3500 head hisses when you turn the tube preamp up (at all) and pops. The closest sound to it would be cooking bacon on a frying pan!

    I saw threads about turning the faders and high contour knob down, but i have to cut ALL highs to get rid of the hiss.

    The pop however remains, just sounds like dull thuds though.

    I've had the amp for 4 years and it may have been turned up too loud by friends at some stage 2 years ago when I wasn't with them when they used it.

    Also a couple of months ago my girlfriend turned my head on without any speakers plugged into it and turned everything on the head up. When I saw it after she had turned it off, I plugged my bass in to scope the damage. The amp hissed a lot, but after a few days it went back to "normal" (the hissing and popping described above).

    So I guess my questions are:
    1. Could it just be the tube?
    2. Could my amp be broken beyond repair ( :bawl: )
    3. Can I fix this myself?
  2. Kael

    Kael Supporting Member

    Dec 26, 2004
    Oklahoma City
    Your GF powering up/diming the knobs on the head without a load shouldn't have harmed anything. Hartke's are just hissy. It is especially noticeable if you are using a cab with a tweeter. I used an old MOSFET 3500 for years. The only way I could kill that hiss was by pulling the high fader down. If I was using a cab with a tweeter that would usually mean almost ALL the way down. On the gig I'd usually creep it back up some, as it was not noticeable in a mix. Was truly irritating for solo rehearsal though.

    If you are using a cab with a tweeter, have you tried adjusting the attenuator for the tweeter?
  3. BillyB_from_LZ

    BillyB_from_LZ Supporting Member

    Sep 7, 2000
    I agree with Kael that running the amp without a load shouldn't cause any damage. However, you should seek compensation after the problem is fixed just to prove a point! ;) :eek:

    About the popping new is the tube? When was the socket cleaned last? Has the amp been dropped or been subjected to a lot of vibration between the time it sounded fine and now? Maybe simply reseating the tube will fix it...maybe the socket needs to be cleaned, maybe the tube needs to be changed.

    Beyond that, if it was a old Fender guitar amp, I say that changing the 100K ohm plate resistors for the preamp tubes would fix the problems. Sounds weird, I know, but I've done it and it does work...

    Looking at the schematic for the 3500's preamp, there are two 100K resistors near the tube...R109 on the plate of "tube-b" and R111 on the cathode of "tube-a". For one that knows what they're up against (like the potentially lethal hazards associated with servicing electronic equipment), I'd replace those resistors after trying the less invasive things I suggested earlier.

    The one other component that I'd suspect is C10B which is a 0.1 uF (200V) coupling capacitor between the output of the tube section and the filtering network before it joins the solid state section.

    Note: I'm not a trained service tech...just a dork engineer who's been sticking his nose in instrument amps on and off for a long, long time.

    You might want to enlist the help of PsychoBassGuy...he knows tube gear and can probably offer some suggestions. I can provide a schematic if needed.
  4. I'd have to side with Billy_B. I bought a Hartke combo (1155) some years ago, which has the 3500 head, and the tube side of the preamp was sounding awful. Crackling and popping, in synch with how loud or hard I was playing. Being something of a tech, I took it all apart and looked first at the seating of the tube (no problem there), then starting wiggling components near it, and voila! I found an electrolytic capacitor (don't know the board position) that was barely connected to its solder trace. It actually had one lead broken, IIRC. I had to find a replacement from a repair shop, soldered it in, and it worked 100%! Still have that amp, and it kicks it when called upon.
  5. Well it was definitely different. It was a very loud hiss, but now its back to the first post description.
    I can't get angry at my girlfriend. I love my gear to bits, but my girlfriend a whole lot more!
    I bought the amp new just over 4 years ago, never changed the tube.
    No idea on the socket cleaning date, best guess: never.
    Has it been vibrated/dropped? Well not dropped, but it got a bit of a shake around a few times, it very well couldve been enough to need reseating.
    For this last bit, i'll print it out and take it to the place where i'm taking my quad to get fixed (friend used his head to clip my quad... grrrr) to see if they can make more sense of it than I can. I get what you're saying, just not how to do all those things. That is of course if you don't mind :D

    Thank you Kael, BillyB_from_LZ and whacker. Your help is appreciated so much! I've been putting this off for 2 years because it sounded so expensive to fix, but now I may be in a situation where I need to use it, so the time has come to fix it!
    Thanks again!
  6. Just a follow up.

    It was the pre-amp tube. I went and bought one today (Svetlana) and now she sounds better than she was brand new!

    I now have little faith in Sovtek tubes :(
  7. Why? Four years isn't bad, especially if the amp has been gigged. Sovteks do vary AFA sound goes but I have some that have performed freaking magic when plugged into the right amp. All tubes have a finite lifetime and are vulnerable to mechanical damagefrom vibration and handling.

  8. It has never sounded like it does right now. Even when I first got it. Maybe it was shipped not working correctly and I just thought it was normal, but the sound now is just amazing!
  9. Trevorus


    Oct 18, 2002
    Urbana, IL
    A lot of people say that. This is one cheap and easy upgrade you can do to a hartke 3500 to change it completely. They are good amps, and a good experiment base for preamp tubes.

    Most people notice a marked improvement over stock with a tube swap.
  10. I'm actually very glad for you on that account. It really stinks when your amp doesn't work right.

    I had a Mesa Boogie that was the most frustrating amp ever. I could never get the sound that everyone always raved about - it always sounded like crap. One day, in frustration, I stripped the preamp tubes out of some of my other amps (I had already played with the power stage) and started to try them out one by one. After putting one particular tube in the first preamp slot, I turned it on and the sound was amazing. The funny thing is that the magic tube that got me that sound was a generic Sovtek that came as original equipment in a cheap Electar/Music-Yo amp.

    Sometimes we can't predict what will work.

  11. Well over the last 4 to 5 years I had this idea of a certain tone I wanted, and no matter what I did, I couldn't get my amp to do it. Now it's perfect.. I'm so happy because I was going to take it into a shop to get it repaired, but it would cost me a minimum of $110(AUD) just for them to see it (hourly labour rate). So this has saved me the money!

    You wouldn't believe how happy I am at the moment. All I have to do now is get a grounding problem on my bass fixed (Stingray) and all will be perfect :D