Hartke HD75 rattle on D

[Newb Craig]

Greetings. I am a new bass player at 52 years old (always wanted to play since a teenager) and picked up some used equipment. One of which was a very nice looking Hartke HD75 for a $120. Well…when I got it home I discovered something odd. I get an annoying yet subtle rattle on any D note I play. I have attempted to isolate this but running out of ideas.

I have:
-tightened everything up I can find
-pulling the head unit to reposition any wires that might be vibrating
-put electric tape under mounting points of head unit
-tried blocking the port
-tried extra foam baffling to change resonation
- inspected speaker cones for damage
-tighten from speaker grate

I am new to this so appreciate any help or ideas you could send my way.

Thanks!

 

[agedhorse]

Have you tried it outside to rule out something in the room as the source? The single most common cause.

 

[Newb Craig]

I have not…didn’t know that was a thing. Will give this a try.

 

[Al Kraft]

Congratulations on scoring a sweet little combo. Agedhorse's suggestion may provide the answer and quite frequently does - and not just on this topic. It's amazing how often something insignificant/innocent looking in the room is the culprit and even after I verify it, I still have trouble believing it. Picture frames, ashtrays/glassware, and stuff on items on shelves are much better at vibrating at their natural frequency (D and/or its harmonics in your case) than you might imagine.

One other thing I've found that might helpful in troubleshooting if it's the cab is to put a small rag/towel under the handle. With combos I sometimes find that the handle can vibrate at certain frequencies as it's a part that's more free to move (for obvious reasons) than the stuff you have screwed down tight.

 

[Newb Craig]

Thanks Al…I’ll give that a try also.

 

[Al Kraft]

By the way, a very exhaustive and well thought-out list of stuff you already tried. Poorly routed/secured internal wiring and loose damping material hitting wiring as the air moves it around are all possibilities often overlooked.
Good luck getting this sorted...let us know what you find.

 

[S-Bigbottom]

Some little knick knack vibrating in the room is all it takes.
Yes it sounds like the cab but it is that porcelain unicorn on a shelf with a spring loaded rainbow around it.

G vibrates the dishes and knick knacks in my house, sounds like my cab is blown.

Good luck on your search.

 

[Yahboy]

I meet rattle/vibrate on my previous Hartke KB15 and i found it cause by 6 metal piece(work like screw nut) which using to hold the amp chassis, means the amp chassis are floating and the top are attach to cabinet wood once screwed.

I unable solve the problem since those metal piece are design in "non-attach" condition, they just lay inside U shape metal brackets. I believe it is design failure, otherswise, this combo sound great !

 

[Newb Craig]

Thanks for the tip Yahboy.

 

[agedhorse]

Properly installed, the cage nuts do not rattle. They have been used for decades without issues, so I wouldn't jump to that conclusion without investigating it thoroughly.

 

[Yahboy]

Thanks for the tip Yahboy.

To avoid confuse, those highlight circles just a location i wanna telling for , but not those ring cause rattle, there are metal pieces on amp metal casing which using to connect those screws, you can't found it until you remove the casing.

Meanwhile , KB has different assembly compare to HD combo. I cant sure both has same design on metal casing.

 

[Hounddog409]

Have you tried it outside to rule out something in the room as the source? The single most common cause.

This. I have a rattle in my room on the B. Doesnt matter which amp i am using.

 

[Newb Craig]

Update on some testing…
Played it outside and the rattle is consistent so it’s nothing in the house. Also “stabilized the handle with a towel without any improvement.

Any other suggestions?

I will note that the white baffling material inside is not consistently laid out across the walls but bunched in a way that nothing is around the port. Is this how it should be? The speaker is glued in addition to be screwed in so I really can’t get a clear picture of how it is laid out.

 

[6thplanet]

Try sitting it on its side and possibly sitting on it to see if that changes anything.

 

[basscooker]

Is the logo secure?

 

[bigdaddybass12]

Long shot, check for a moisture pack inside the cabinet.
One more, I had an amp that had a rattle, it was a loose screw that mounted the circuit board to the amp chassis.

 

[BrassedOn]

Also being careful, cab on its back, keeping the wires connected but removing the speaker and setting it propped just above the hole, and play. Sometimes I can hear better the source of the issue.

Sadly On a different brand, a single pitch buzz on a low pitch was precursor to speaker going bad. Using a high pass filter cut some deep lows (below 40hz) gave me a little grace but ultimately had to replace.

 

[Newb Craig]

Thanks for additional ideas.

-Logo is secure
-All chassis screws are tight
-Turned it on its side…no help
Sat on it in its normal upright position and eliminated noise.

What does this mean?

 

[basscooker]

Jointing or bracing issue is likely.

Ooh but just to be sure, double check it isn't anything related to the top handle or the feet.

 

[Newb Craig]

The speaker is glued in…it there another way to access the inside cab on these Hartke amps.