Hi Folks,
Some months ago built a pair of MTM speakers for low volume PA and bass guitar use (with a subwoofer in both cases).
Each box contains two Eminence Alpha 6 woofers and a Celestion CDX-1445 compression driver. They are passively crossed over 12db/oct at 2.2kz.
Their performance has been beyond my expectations, however recently when pushing the system with recorded music and playing along with bass guitar I blew the tweeters in both boxes.
The power amp was hard limited so as to not exceed 200w per box (thermal rating of the woofers).
Part of the reason the HF drivers went was because I was playing with a bass overdrive pedal.
I understand that light globes can be used in series to protect against such failure, but I have no idea where to start.
The compression drivers are rated at 20w.
Can anyone suggest a suitable light globe to run in series with the HF drivers, or alternatively some other measure to help idiot proof these boxes?
Some months ago built a pair of MTM speakers for low volume PA and bass guitar use (with a subwoofer in both cases).
Each box contains two Eminence Alpha 6 woofers and a Celestion CDX-1445 compression driver. They are passively crossed over 12db/oct at 2.2kz.
Their performance has been beyond my expectations, however recently when pushing the system with recorded music and playing along with bass guitar I blew the tweeters in both boxes.
The power amp was hard limited so as to not exceed 200w per box (thermal rating of the woofers).
Part of the reason the HF drivers went was because I was playing with a bass overdrive pedal.
I understand that light globes can be used in series to protect against such failure, but I have no idea where to start.
The compression drivers are rated at 20w.
Can anyone suggest a suitable light globe to run in series with the HF drivers, or alternatively some other measure to help idiot proof these boxes?
The limiting does not seem to produce any distortion that I am able to sense.
I'm close to certain that the overdrive pedal on my bass guitar (along with the recorded music neing at or near the limiter) was the cause of the problem. I thought I had idiot proofed the system with the limiter, but it can still feed 200w into the tweeter if the content is there, and the overdrive creates plenty of harmonics in the compression drivers register.
I like a bit of overdrive with my bass, so some kind of additional limiting for the HF section is needed, but I need help determining what.
I'm close to certain that the overdrive pedal on my bass guitar (along with the recorded music neing at or near the limiter) was the cause of the problem. I thought I had idiot proofed the system with the limiter, but it can still feed 200w into the tweeter if the content is there, and the overdrive creates plenty of harmonics in the compression drivers register.
I like a bit of overdrive with my bass, so some kind of additional limiting for the HF section is needed, but I need help determining what.
Some have said that a filament based auto blinker bulb is useful in this situation. It may be worth looking for references or if you happen to have one handy, measure it's cold resistance and calculate it's hot resistance.
Also, how do the CD impedance peaks work with your crossover?
Also, how do the CD impedance peaks work with your crossover?
Yes polyswitch or bulb as Allen and Djk suggested in thread linked.
I've seen old JBL control 1 overpowered producing a flash and tweeter off, opened the plastic box and spoted the bulb. It did it's job.
Polyswitch i had ( i bypassed it) in my main loudspeakers too before turning it active filtering. I never seen it working in practice when i used it passive ( once triggered you had to rearm manually).
https://techtalk.parts-express.com/forum/tech-talk-forum/34622-polyswitch-ptc-resistor-sizing
This can help too:
https://sound-au.com/tweeters.htm
Iaxandredeyed, bo you use a compressor in front of your distortion? It helps to keep a more manageable sound with distorded bass, you will have less potentialy injuring peaks. Can even help to have another one after the disto too.
I've seen old JBL control 1 overpowered producing a flash and tweeter off, opened the plastic box and spoted the bulb. It did it's job.
Polyswitch i had ( i bypassed it) in my main loudspeakers too before turning it active filtering. I never seen it working in practice when i used it passive ( once triggered you had to rearm manually).
https://techtalk.parts-express.com/forum/tech-talk-forum/34622-polyswitch-ptc-resistor-sizing
This can help too:
https://sound-au.com/tweeters.htm
Iaxandredeyed, bo you use a compressor in front of your distortion? It helps to keep a more manageable sound with distorded bass, you will have less potentialy injuring peaks. Can even help to have another one after the disto too.
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