Hi everyone, i am planning on redoing a pair of 30 years old crossovers but there are stock in resin. Is there a safe way to remove or melt the resin ??
What model of speaker did the crossovers come out of?
That information may reveal the crossover schematic and avoid what is likely to be a rather messy procedure.
I would break off some pieces of resin (perhaps the corners of the slab) to experiment on.
A safe(ish) first experiment would be to immerse a piece of resin in boiling water.
P.S. I would ask for this thread to be transferred to the Multi-Way section where the crossover experts will see it.
That information may reveal the crossover schematic and avoid what is likely to be a rather messy procedure.
I would break off some pieces of resin (perhaps the corners of the slab) to experiment on.
A safe(ish) first experiment would be to immerse a piece of resin in boiling water.
P.S. I would ask for this thread to be transferred to the Multi-Way section where the crossover experts will see it.
Why do you want to rework the cross over circuit?
Potted in resin, and book value is zero.
Most likely potting compound, a type of epoxy, removal is difficult, and the solvents needed are so strong that you may need special permission from the authorities.
If at all they work.
Very likely you will damage the parts inside.
Think HF, Conc. HNO3, H2S2O7, and the like.
Blow lamp will work, smelly, needs ventilation.
Old caps, maybe the inductors can be salvaged.
Work out your hourly rate at work, think of spending 8 hours, compare that to the price of a new circuit, if viable, do it.
Potted in resin, and book value is zero.
Most likely potting compound, a type of epoxy, removal is difficult, and the solvents needed are so strong that you may need special permission from the authorities.
If at all they work.
Very likely you will damage the parts inside.
Think HF, Conc. HNO3, H2S2O7, and the like.
Blow lamp will work, smelly, needs ventilation.
Old caps, maybe the inductors can be salvaged.
Work out your hourly rate at work, think of spending 8 hours, compare that to the price of a new circuit, if viable, do it.
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Thanks for you advice, i will try to melt a sample in boiling water.
It's an old pair of apg mobil 1, they are pa speakers but fully equipped with old school audax drivers and they sound pretty nice.
I have asked many times the apg company for the schematic but no positive answer!
I can hear the loss of bass after 3 hours of heavy play on them. The caps are very tired...
I don't see the connection between loss of bass after 3 hours and "tired" caps.
Could it be due to the bass driver voice coils overheating, resulting in power compression?
https://www.ajaudio.co.uk/Loudspeaker thermal compression.htm
I think the "3 hours of heavy play" is the clue to why there is a loss of bass.
Power compression occurs first in the woofer and causes an imbalance in frequency response i.e. a reduction in the woofer level compared to that of the midrange and HF.
Perhaps you are playing at too high a volume for these particular PA speakers?
Power compression occurs first in the woofer and causes an imbalance in frequency response i.e. a reduction in the woofer level compared to that of the midrange and HF.
Perhaps you are playing at too high a volume for these particular PA speakers?
The power compression is due to the rise in DC resistance of the voice coil with increasing temperature which results in a decrease in sensitivity.
The temperature of the voice coil will become high in 10-15 minutes of high power not in 3 hours. In 3 hours of heavy play the temperature of the magnet will also becom high and the magnetic force will decrease doing power compression.
I'm with you, sesebe.
The magnetic strength will return as the magnet cools (provided the magnet's maximum operating temperature is not exceeded).
The magnetic strength will return as the magnet cools (provided the magnet's maximum operating temperature is not exceeded).
I haven't thought about the compression and heating problem of the voice coil, that's interesting.
The low drivers are Audax PR380T4, 8 ohm, should be able to take load !
I was expecting the problem coming from the capacitors being dried out after 30 years and the frequencies going all over the place when the getting warm...
The low drivers are Audax PR380T4, 8 ohm, should be able to take load !
I was expecting the problem coming from the capacitors being dried out after 30 years and the frequencies going all over the place when the getting warm...
There may not even be any capacitors in the woofer circuit at all, there may be only an inductor.
Tired caps will show up early, within minutes.
They fault is elsewhere, maybe your amp is overheating / like above magnets going weak with heat.
See if a heat protection circuit is there in the amp, if not, put one on the heat sinks near the outputs.
So, first, why do you need such high volume levels?
Tell us location, area, type of music.
If it is a small to medium room, and you are in need of loud volumes, get your hearing checked.
If not, large area, concert / church / hall, get more speakers, higher output amp.
They fault is elsewhere, maybe your amp is overheating / like above magnets going weak with heat.
See if a heat protection circuit is there in the amp, if not, put one on the heat sinks near the outputs.
So, first, why do you need such high volume levels?
Tell us location, area, type of music.
If it is a small to medium room, and you are in need of loud volumes, get your hearing checked.
If not, large area, concert / church / hall, get more speakers, higher output amp.
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