Wondering about Polyswitches

motorstereo

Aha; so I have some of my buddy's handiwork that I listen to every day:cheesygrin:. Nice job on the crossovers. I looked them over when I had them out for the new plates. You also did the cardas posts I believe; nice job on those as well.
I also had thought they needed the resistors till I read DK's comparison chart. According to my ears and DK's tests Joe made the correct decision.

transmaster

bmbguy wrote: »

The spec sheet for the RXEF050 that transmaster linked to yesterday had:

Rmin (?) = 0.50
Rmax (?) = 0.770

That matches what I've seen other places. So those opting for the 0.5 ohm resistor are right in the ballpark.

The link takes you to the this explanation for Rmin, and Rmax:

The resistance of a PolySwitch device under specified conditions (e.g., 20?C), before connection into a circuit. Devices of a particular type will be delivered with a range of resistances; therefore, a minimum value, Rmin, and/or a maximum value, Rmax, are often given.

Again this is one of the things I like about Allied Electronic if there is any part you need the complete spec's on and Allied sells it there will be a data sheet available

I am going to go ahead and install new polyswitches at .34 cent each at Allied really cheap insurance and as I said earlier my decades of playing in Jazz, and Big Bands in low brass sitting in front of or standing very near the trap set means my ears are far from golden, maybe corroded copper. :cool:

I do remember the 10B who's XO has failed the Polyswitch was tripping a lot in the past. I didn't know anything about a Polyswitch I just called it a thermal overload switch. When I did the DX'ing on the XO I found the Polyswitch was bad. I twisted the polyswitch to connect the wire leads togather and the tweeter started to work again. The cap's are way out of spec's as well, and the electrolytic is a goner.

transmaster

I have had the fear of the Audio God put into me. My New Onkyo TX-NR709 failed in the process of that failure it lunched the voice coil on the Right channel (in Stereo mode) 8 inch woofer on the Wharfedale W-35's. I suddenly had a jackhammer sound an instant before the protective system in the Onkyo cut things off. the rig never to work right again. A Polyswitch would not have protected the woofer in this case but I wonder if I fused the whole speaker if it would. I wonder what value I should use. Slow or fast blow. Crutchfield is replacing the receiver but having a failure like this puts a person on guard,

Joe08867

I would use fast blow fuse but it probably wouldn't have mattered anyway. When the Onk went it was taking that speaker.

I have killed tweeters that were fused with just distortion.

transmaster

Joe08867 wrote: »

I would use fast blow fuse but it probably wouldn't have mattered anyway. When the Onk went it was taking that speaker.

I have killed tweeters that were fused with just distortion.

I was reading about an Amp going DC I wonder if that is what happened. As bad as this was you have not lived until you have a Heathkit SB-220 HF Amp take off with parasitic arcing, and the whole thing all but blows up, some of the circuit on these Green Pigs have 2400 volt with enough amps to instantly kill you when they let loose is a fantastic cascade of smoke and flashes, the big electrolytic capacitors exploding. Every time you fire up one of these old HF amp you have the feeling of a bomb waiting to go off.

Joe08867

I saw that once at a shop. They were bringing up an old heathkit slowly and blammo it went. Pretty dang scary if you ask me.

transmaster

Revisiting this thread: When push came to shove I decided to go with the resistors to that end I have a pair of 0.5ohm 12 watt millers to replace the polyswitches. I was thinking in the past one of the 10B's was always a PIA with the tweeter cutting out, now I know what was causing it. When I was testing to make sure the problem with that speaker was not in the drivers. The leads on the polyswitch were long so i just twisted the leads togather and the tweeter came to life, the two 6 1/2 driver where also ok.

A couple of days ago I finished rebuilding the Warfedale W35's, used Dayton cap's, I also had to replace the 8" woofers. The First Onkyo NR-709 when it let loose, it let loose on the right hand W35 in a split second it jack hammered the 8" BIC-8950 into oblivion. I replaced both with, the NHT 1-11-084-011 8" Woofer, $10.95 from http://www.apexjr.com/speakerstuff.html As these speakers break in they are sounding better and better. For 10.95 I think I am going to get a couple more pairs of them to salt away for future use. The transparency the recapped crossovers has contributed is astonishing.

It is going to be fascinating to see how the Monitor 10B's will sound. It will have Sonicap Gen 1's for the high pass, and Axon True Cap's for the low pass and all of the resistors will be Mills.

TennMan

I hope you post a review about your 10Bs once you have the new parts installed. I also have a pair of 10Bs but I have SDA CRS+ crossovers and drivers in mine to get the SDA sound out of them.

transmaster

TennMan wrote: »

I hope you post a review about your 10Bs once you have the new parts installed. I also have a pair of 10Bs but I have SDA CRS+ crossovers and drivers in mine to get the SDA sound out of them.

I will indeed report here.

Since I wrote the above note I discovered yet another feature of this, even by my standards,complex Onkyo. Intellivolume, when I noticed it, then learned what it was for, for adjusting the input levels of plugged in equipment to even the sound levels between them. I was wondering it seemed like the NR-709 didn't have much volume. As you might expect it was set to the minimum level. I discovered where the missing volume was, so I turned things up. Holy cow the Warfedales were good before now that I can crank them up wow! I am really looking forward the recapped 10B's now.