On 28/10/2015 1:47 AM, wrote:
On Monday, October 26, 2015 at 4:44:13 PM UTC-4, Trevor Wilson wrote:
On 27/10/2015 3:58 AM, wrote:
On Sunday, October 25, 2015 at 7:12:18 PM UTC-4, Trevor Wilson wrote:
On 26/10/2015 6:32 AM, Gareth Magennis wrote:


"Trevor Wilson" wrote in message ...

On 25/10/2015 11:54 AM, Gareth Magennis wrote:


"Trevor Wilson" wrote in message
...

On 25/10/2015 8:49 AM, Gareth Magennis wrote:


"Trevor Wilson" wrote in message
...

On 24/10/2015 3:07 PM, wrote:
Cylindrical. Axial leads.

Ordered caps for a speaker crossover because the leads had literally
been shaken out of the originals. But I had no luck finding those
bulbs. I would rather not jump it out. I guess I could and just put a
beefier horn in it.


**Select an appropriate sized Polyswitch(tm). Cheap, reliable and
effective.





Polyswitches are not compressors.


**Correct. They're much better. They protect drivers, without
significant audible problems (like compression).






Do you think you would be able to hear such a compression problem?

**Absolutely. I've proven it, under blind test conditions, to clients
who own speakers that are equipped with such things.




OK, but the point I didn't quite make yesterday was that you would only
hear such a compression "problem" if the system was being abused, i.e.
overdriven.
This is when the compression kicks in, to protect the tweeter.

**Well, yes it does. However, it depends on the system. For sound
reinforcement, the compression effects are not likely to be a problem,
though most professional systems use far more sophisticated electronic
compression systems.


To single out the compression as a problem is to completely ignore the
simple fact that this is happening because of a far bigger problem
elsewhere, and the volume needs to be reduced before something blows up.

**In domestic systems a Polyswitch(tm) is, IMO, a better choice.

I located and measured a long, thin filament lamp (which looks like a
baretter). Part # GE1936. Nominally, I would guess it is a 12 Volt lamp.
At 12 Volts, current consumption is 0.75 Amps. Here is the resistance
plot, vs. current:

0.1 A - 1.7 Ohms
0.2 A - 2.15 Ohms
0.3 A - 3.4 Ohms
0.4 A - 6.3 Ohms
0.5 A - 9.68 Ohms
0.6 A - 12.53 Ohms
0.7 A - 15.13 Ohms
0.75 A - 16 Ohms

A Polyswitch(tm) typically exhibits insignificant resistance changes, until
the switching point is reached. They're self-resetting and, provided
Voltage ratings are not exceeded, quite reliable.

--
Trevor Wilson
www.rageaudio.com.au

---
This email has been checked for viruses by Avast antivirus software.
https://www.avast.com/antivirus

Hi Trevor, I'm not an audio guy. But one thing about polyswitches is that
they do age.. the more times they trip the lower the trip point.
I don't know if that would be an issue where you use them.


**Whilst I have not noticed the effect you describe, I do not suggest
that you are wrong, but it would be instructive to know how many trips
lead to unacceptable aging. That figure would need to be balanced
against the life-span of a baretter.
I wrote an email to littlefuse a while back when I noticed this effect.
I went looking (for where I might have put the data.)

OK here's a link to where I asked the question on Stack exchange.
http://electronics.stackexchange.com...e-ptc-lifetime

Lot's of numbers there.. And I summarize the data from littlefuse.


**Raychem (the inventor and the only supplier I use) cites something
like 2,000 resets, before significant resistance changes occur.


--
Trevor Wilson
www.rageaudio.com.au

---
This email has been checked for viruses by Avast antivirus software.
https://www.avast.com/antivirus