Hartke 210C Dilemma - Help Please

Discussion in 'Amps [BG]' started by jcurrie, Feb 22, 2014.


  1. jcurrie

    jcurrie

    Joined:
    Feb 22, 2014
    I just bought a Hartke 210C combo. The problem I am having is that anything played under about 110 Hz makes the speakers flutter terribly. I wasn't sure if this was the way it's supposed to sound or if I had a problem. I connected a signal generator to the input add swept the freq from 20-200 Hz while monitoring the output signal to the speakers with a scope, looking for distortion. The input voltage was 76mVrms (215Vpp). At 1 on the gain things were pretty good however the output signal drops off dramatically below 80 Hz. When I got to 3 on the gain anything below 80 Hz just made the cones flutter. I could hear the fundamental faintly but most of the sound I heard was flutter. The output signal looked like a perfect sine wave so I assume the speakers or cabinet design is the issue.

    I spoke with someone from the factory and he said it was normal for it do it at little (which surprised me), but he said that sounded excessive. Later I got another call and that person said it may be the dust covers coming loose. I went and checked - all looked good - sealed all around. He said I could return it to the factory for warranty work. My dilemma now is that this is a ported cabinet which I've never used on bass and am wondering if this is just the way it's going to sound and they'll find nothing wrong. I have a sealed enclosure GK combo and also other sealed cabinets and I don't have any problems. I did a lot of checking before trying a Hartke. Surely there must be something wrong. I don't believe they would sell an amp with an EQ pot centered at 80 Hz, designed for bass, and a gain that goes to 10 if it can't reproduce the bass instrument fundamentals (E thru G, 42-98 Hz) with out it sounding like a flock of birds taking off when pushed above a gain of 3. Does anyone else own one that could tell me if they all sound like this or have I made a terrible mistake? I'm not trying to push the fundamental but I do like it to be there without it sounding like I'm playing through a fuzz box. I would appreciate any opinions or experiences others have had. I don't know what to do or what to expect from a factory warranty look over - it costs a lot to ship 63 lbs.
  2. tubatodd

    tubatodd Supporting Member

    Joined:
    Oct 31, 2004
    Location:
    Birmingham, AL
    I had a similar issue with my kickback combo. I thought I busted the cone. I purchased an eminence replacement and it fluttered as well. In my case it was the batting inside the cabinet. Even though everything was tight and secure I had to add another layer of polyfill batting. After that I've had no problems.
  3. AstroSonic

    AstroSonic Supporting Member

    Joined:
    Dec 10, 2009
    Location:
    rural New Mexico
    It would be normal behavior if the cab were tuned relatively high (like 85-100 in this case), such that the drivers are unloaded below the tuning frequency. If you don't like it , but can't return it, try either of the following: 1) reducing the resonance Q by stuffing some teased-out insulation in the port(s) - this will reduce the fluttering, but also the bass added by the port(s). 2) try using it as a sealed cab by stuffing the port(s) tight with an old towel or wash rag (whatever's handy).

    There is a remote chance that the amp is only marginally stable at low frequencies. Trying the amp with a different (non-fluttering) speaker would answer that.

    Good luck!
  4. jcurrie

    jcurrie

    Joined:
    Feb 22, 2014
    What would sealing the port do? Can that damage the drivers?
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  6. AstroSonic

    AstroSonic Supporting Member

    Joined:
    Dec 10, 2009
    Location:
    rural New Mexico
    Sealing the cab will allow the driver to be loaded to the lowest notes of your instrument. As a result, cone motion will be considerably less. Sealing a high-tuned ported cab may actually result in a fuller, more pleasing bass. However, without TS parameters and box volume, there is no way to tell without trying. Of course, how you feel about the resulting tone is a matter of personal preference.

    Sealing the cab is a good place to start. If you prefer a tone between sealed and ported, that's when to try adding insulation to the ports. Listen to the resulting sound and watch those cones for over-excursion. The more insulation you add, the closer you get to sealed.

    There are two common ways to damage a drive: 1) over excursion, and 2) thermal overload. By sealing the cab cone motion will be reduced for the lower notes. The amp manufacturer generally selects the drivers to be safe from thermal overload with the included amplifier. It is sometimes the case that large amounts of bass boost can cause over-excursion (farting out). As a musician, you need to always be aware of the sound quality coming out of your speakers. If the speakers sound stressed, it's time to cut some bass or volume.

    Edit: Just a last minute check - how much excursion are you seeing? Roughly, a 1/4 inch, 1/2 inch, etc., and at what volume? Don't pay attention to the dial position. How loud is it? Also, have you checked to verify that 1) the drivers are securely screwed down (no air leaks), and 2) that the port tubes are properly attached - sometimes the cardboard tube extension (off the plastic rim/flare) actually comes off during shipping and is lying lose inside the box.
  7. jcurrie

    jcurrie

    Joined:
    Feb 22, 2014
    I wouldn't say there was about a 1/4 travel max in the speaker when I am playing normal in my room. The track level is about 75-81 db without the bass. Then matching the bass to the track the bass is about 75-84 db when played by itself (measured about a yard away. The port is a formed plastic piece that is flared on the outside edge of the cabinet. It has a 4" ID and protrudes into the cabinet 4". If I cut the EQ on everything except 80 Hz, anything played on the E string will begin to flutter at 72-74 dbs. I tried stuffing the port as you suggested and you were right - it greatly attenuates the bass but the flutter was gone. The interesting thing was that with it plugged any note on the E string between A and 12th fret E and also an octave up on the D string sounded dead and muted - no sustain?? I partially blocked the hole and gained a few frets. Maybe there is some combination of blockage that will get the notes back and still not produce that terrible sound. I can almost bare to lose some bottom if it will great rid of that fuzz, but I can't stand to lose entire sections of the fret board. Would more damping material inside the cabinet help rather than plugging the port?
  8. AstroSonic

    AstroSonic Supporting Member

    Joined:
    Dec 10, 2009
    Location:
    rural New Mexico
    To maintain the lively character of the sound keep the amount of damping material inside the cabinet to a minimum: just a thin (less than 1 inch) layer on the back and one side should be sufficient.

    To evaluate the sealed box option, make sure that the cab is tightly sealed - those ports need to be stuffed tightly. Otherwise the cab behaves as a restive reflex (or aperiodic) enclosure. With drivers with the appropriate characteristics, an aperiodic box can sound quite lively and have great sustain. Your drivers evidently don't work well in a sealed box, but may work well in a resistive/aperiodic box.

    Yes, it's very possible to find the right amount of stuffing in the ports for the sound lively and have good sustain. You had the right idea - keep making small changes until you get the sound you like. Remember, that as you get close its worth adding a little EQ. Better to have a little too much material in the ports than too little.

    Honestly, it's hard to believe that this performance is what was intended by the manufacturer. I wonder if something is out of spec.

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