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Trying to make my Ampeg 410HLF stop lighting up

colantalas

colantalas

Mar 26, 2014
194
237
#1
I like to have a pretty bright tone. I get this by playing Jazz-style basses into a Darkglass B7KU into a Hartke HA3500 head and Ampeg 410HLF cab. I like my tone, but I've noticed an issue where a shrill frequency comes though the cab. When it happens it causes a lightbulb behind the speakers to light up, which according to Google means that you're close to blowing the speakers, which I don't want to happen. I've tried to reconfigure my setup plenty of times to make this stop happening, but eventually an errant pick scrape or something will make the cab light up like a Christmas tree. What's even more confusing is that I don't feel like I have that much high end dialed into my tone - I have treble at noon and drive and hi mids (3Khz) at 1:00 on my Darkglass, and on the Hartke my high pass filter is at noon and my graphic EQ is flat, except for a slight dip at 30Hz and a sharp cut at 8Khz. The tweeter on the cab is also kept off at all times, and I'm using roundwound strings on a passive bass but they're not exactly brand new. I also have volume on the amp at around 3, and the input light on the amp stays solidly green. Anyone have any insight, maybe an idea which frequency is causing harm to my cab? I'm thinking about replacing the speakers with neodymium speakers to reduce the weight of the cab, would they be able to handle it without freaking out? This has been bothering me for months and I'd like to nip this in the bud permanently.
 
#2
As I recall, the bulb acts like a fuse for the tweeter.
If you don't use the tweeter, then consider taking it out of the circuit by disconnecting before the crossover.
OTOH, if you like a bright tone, why not use the tweeter?
 
#3
Jim C said:
As I recall, the bulb acts like a fuse for the tweeter.
If you don't use the tweeter, then consider taking it out of the circuit by disconnecting before the crossover.
OTOH, if you like a bright tone, why not use the tweeter?
Click to expand...
Two reasons:
1. I'd like my tone to be bright without the tweeter, because that's what goes to the FOH. Most of my tone comes from my bass and pedalboard, my amp basically exists just for light EQing, stage volume and to provide an XLR out.
2. I just don't care for the tweeter sound, kind of harsh and the brightness is overkill IMO.
 
#4
The lamp does indeed protect the tweeter's voice coil. At cold the lamp filament has a lowish resistance so doesn’t affect the signal going to the tweeter that much. As it lights brighter the lamp's resistance increases reducing the signal that the tweeter sees. This saves the tweeter from damage.
 
#5
No worries; disconnect 2 wires and your problems are solved
If I am correct about the bulb acting like a fuse, you could also just remove the bulb to keep the tweeter out of the system

Edit: Simulpost with Paul.
Paul, just pull the bulb and everything is groovy, correct?
 
#6
Jim C said:
As I recall, the bulb acts like a fuse for the tweeter.
If you don't use the tweeter, then consider taking it out of the circuit by disconnecting before the crossover.
OTOH, if you like a bright tone, why not use the tweeter?
Click to expand...
^This.

Or, add an adjustable HPF/LPF like Broughton to the end of your signal chain.

It'll cut off the sub-sonic noise, protect your speakers and allow you to cut off the top end where you want.
 

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