SDA Polyswitches Are Nasty

Face

F1nut wrote: »

Buy a mo' better amp.

Correct!

mmadden28

heiney9 wrote: »

It does make sense but the length of wire would dramatically increase the time before the poly breaks the circuit. That distance of wire will dissipate the heat generated when overdriving your tweets. Heat is what causes the ploy to open...

That doesn't make sense. The heat of an over current situation is generated by the current passing through the 'circuit breaker' (or poly, fuse, etc). The heat isn't generated at the circuit board with the potential to be dissipated by the extra 24" or so of wire located at the binding post cup.


Older model Monitors were protected with a fuse that was located at the binding post cup (as opposed to a resettable polyswitch) and they worked as designed, the heat wasn't dissipated en-route. Apparently the polyswitch (or lack thereof) was an improved design over the external fuse.

The concept of using a resettable circuit breaker is essentially the same as the older design of using a fuse. I recall it being discussed before, but it was also including talk of the option to replace various inline with the tweeter resistor values to play/experiment with to get a different sound from the tweeters, esp after removing the polyswitch. Apparently some preferred a 'hotter/brighter' highs where others might prefer a more laid back sound. I think this is much like the selector knobs on the back of some of the older vintage speakers where you could tailor the sound curve.

In the end though, because wire has resistance and capacitance, as well as the additional connections, the less extra stuff the better. I can't say if it will or won't affect the sound at these short lengths-I guess that depends on how sensitive your ears are.

audio_alan

mmadden28 wrote: »

That doesn't make sense. The heat of an over current situation is generated by the current passing through the 'circuit breaker' (or poly, fuse, etc). The heat isn't generated at the circuit board with the potential to be dissipated by the extra 24" or so of wire located at the binding post cup.

.....

In the end though, because wire has resistance and capacitance, as well as the additional connections, the less extra stuff the better. I can't say if it will or won't affect the sound at these short lengths-I guess that depends on how sensitive your ears are.

So, if indeed the heat is generated internal to the polyswitch, then the extra wire wouldn't make any difference in the tripping time. The only drawback would be the additional connection, etc, as mmadden28 pointed out. It still might be too much trouble to mess around with though. I think I'll just take the advice of getting a "mo' better amp".

Toolfan66

I have been running a jumper in my 1.2tl's since day one, Yesterday I took out the jumper and put in a .5ohm resistor I can say I like it much better.

DarqueKnight

What improvements did you hear with the 0.5 ohm resistor?

xoaphexox

I ran mine with a .5 ohm Mills for several months and thought they sounded veiled. Popping in a .2 ohm Mills instead made female vocals and cymbals come alive in my case.

MillerLiteScott

I run a .22 resistor in mine. Works for me. The jumper was to bright and unbalanced. .5 was to veiled and did not sound right to me.

Toolfan66

putting in the resistor smoothed out the sound and I guess I never realized how bright it was till I put in the resistor.

Thanks for the info above I will try some other values as well..

audiocr381ve

I'm going to order the .22 Mills and see what happens.

Joe08867

I have .5 resistors in all of my SDA's. Smoother is the only description that fits.

They can be quite bright without the resistor. But some like that, I do not.

audio_alan

Man, I need to do this mod badly on one of my sets of SDA's. I have one speaker that trips frequently when at loud levels, and that "level" seems to be getting lower and lower. It's annoying to say the least. One minute I'm rocking out, and the next ... "What the @%#$?" :mad:

dorokusai

A jumper to remove all the coloration that may or may not exist works fine too. As far as adding a resistor to the mix, and I respect the opinions offered, don't believe it's anything but placebo.

Get rid of the Polyswitch, period. Whatever method you choose, fine.

audiocr381ve

dorokusai wrote: »

A jumper to remove all the coloration that may or may not exist works fine too. As far as adding a resistor to the mix, and I respect the opinions offered, don't believe it's anything but placebo.

Get rid of the Polyswitch, period. Whatever method you choose, fine.

That one statement right there got me super curious tonight. I went ahead and removed the .5 ohm Mills resistors from my SDA-2B TL's, replaced them with jumpers, and have been listening for the past hour to Norah Jones & John Mayer.

I still need more evaluation time but my initial impressions are really good. The first thing I noticed besides the obvious increase on the top end was a lot better coherency in the vocals. I haven't run across a song that was overly bright. I think the words "bright" and "harsh" are often interchangeable, and they shouldn't be. The speakers are definitely a little on the brighter side now but not in a harsh way. It sounds really good now, but I still need more time.

The inductor mod is a must now the Larry has had such a good experience. I can't wait to tackle that one.

audiocr381ve

Got in a couple more hours of listening last night and I've been popping in my favorite tunes all morning. I like the change and they're going to stay this way! I'm experiencing better coherency from tweeter to mid driver. Like Mickie D's, I'm loving it.

Face

dorokusai wrote: »

A jumper to remove all the coloration that may or may not exist works fine too. As far as adding a resistor to the mix, and I respect the opinions offered, don't believe it's anything but placebo.

I don't believe so, when voicing speakers .5-1ohm can make a subtle, but noticeable difference. The kind of resistor makes a difference too.

Toolfan66

Face wrote: »

I don't believe so, when voicing speakers .5-1ohm can make a subtle, but noticeable difference. The kind of resistor makes a difference too.

I agree they are subtle but I noticed the difference right away, I have been wanting to try a different resistor the .5 is the only mills in the mix on my xovers now..

dorokusai

Face wrote: »

I don't believe so, when voicing speakers .5-1ohm can make a subtle, but noticeable difference. The kind of resistor makes a difference too.

Like I said, respect the opinion but I don't agree. It's not like it's expensive to try so knock yourslef out folks.

audiocr381ve

dorokusai wrote: »

Like I said, respect the opinion but I don't agree. It's not like it's expensive to try so knock yourslef out folks.

No polyswitches or resistors ROCK. I've been listening all day with only the jumpers and I'm hearing more coherency then I ever have before. Piano's sound "right." Vocal separation is improved. Me likey.

jmitchnh

One thing I've noticed on my (new to me) Monitor 12 S2s is that the highs seem a bit weak. I can hear sound from the tweeters but the high end seems softer than the lows. This is something I never experienced in my SDA-1Cs. According to the schematic, there is a RDE 090 polyswitch in paralell with a 4.2uf cap. Although I am planning on recapping the x-over in the near future, any danger in just removing the poly to see if it makes and difference? Since it's in paralell I am assuming I do not need to jumper it?

TennMan

I think you will have to jumper it. When closed it is part of the circuit. If you simply removed it the tweeter would stop working as it does when the polyswitch trips.

musky1963

I have 2.3tl's and I would actually like a little more zip to the uppers. So would it be a good thing to remove the polys and use a jumper?

Toolfan66

Yes!!

heiney9

jmitchnh wrote: »

One thing I've noticed on my (new to me) Monitor 12 S2s is that the highs seem a bit weak. I can hear sound from the tweeters but the high end seems softer than the lows. This is something I never experienced in my SDA-1Cs. According to the schematic, there is a RDE 090 polyswitch in paralell with a 4.2uf cap. Although I am planning on recapping the x-over in the near future, any danger in just removing the poly to see if it makes and difference? Since it's in paralell I am assuming I do not need to jumper it?

TennMan wrote: »

I think you will have to jumper it. When closed it is part of the circuit. If you simply removed it the tweeter would stop working as it does when the polyswitch trips.

If it is in fact parallel there is no need to use a jumper if you want to delete using the poly switch. Many other models have the poly in series and in that case you would need to jumper it to complete the circuit. So make sure it is in fact parallel w/said cap. I wasn't aware of series II monitors using poly switches, but then Polk wasn't always 100% consistent from generation to generation. They used up older parts/pieces in newer models so there is some variation across generations.

H9

DarqueKnight

jmitchnh wrote: »

One thing I've noticed on my (new to me) Monitor 12 S2s is that the highs seem a bit weak. I can hear sound from the tweeters but the high end seems softer than the lows. This is something I never experienced in my SDA-1Cs. According to the schematic, there is a RDE 090 polyswitch in paralell with a 4.2uf cap. Although I am planning on recapping the x-over in the near future, any danger in just removing the poly to see if it makes and difference? Since it's in paralell I am assuming I do not need to jumper it?

Notice that footnote "B" informs that the polyswitch and the 4.2 uF capacitor were added together in a circuit revision. The Monitor 12S2 high frequency circuit is identical to the Monitor 12 high frequency circuit, with the exception of the added parallel polyswitch/4.2 uf cap combination. In this case, you would need to take the 4.2 uf cap and the polyswitch out of the signal path. Both can be physically removed and replaced with a jumper or you could electrically "remove" them by putting a jumper across the parallel pair's terminals.

heiney9

DK,

So the cap is part of the protection and not part of the contour circuit? Seems like a large hole in the contour would exist if you just take it out, since it's obviously in the signal path. Note, I haven't looked at the schematic just going by what's be said in this thread.

H9

FTGV

heiney9 wrote: »

So the cap is part of the protection and not part of the contour circuit? Seems like a large hole in the contour would exist if you just take it out, since it's obviously in the signal path.

It appears in normal operation the polyswitch shorts the 4.2 uf cap( taking it out of the circuit).If the levels are high enough to trip (open) the poly switch then 4.2 uf becomes part of the hi pass network.This would allow the tweeter to still have some output but because C3 and C4 are now series connected( the combo resulting in just over 3 uf.) the high pass filter will be shifted to a higher frequency which would afford the tweeter more protection.

Note,I haven't looked at the schematic...

Yet you suggested to remove it?:razz:

heiney9

FTGV wrote: »

Yet you suggested to remove it?:razz:

Yep, sure did based on his explanation and what he was asking. If two parts are hooked in parallel to each other and you remove one part, you don;t need to "jumper" the removed the part to complete the circuit. That's what he asked and that's what I answered.

H9

FTGV

heiney9 wrote: »

Yep, sure did based on his explanation and what he was asking. If two parts are hooked in parallel to each other and you remove one part, you don;t need to "jumper" the removed the part to complete the circuit. That's what he asked and that's what I answered.

H9

The fact that a poly switch is in parallel with a cap should be a direct tip off that something unusual is involved requiring a peek at the sch.Just sayin.

heiney9

FTGV wrote: »

The fact that a poly switch is in parallel with a cap should be a direct tip off that something unusual is involved requiring a peek at the sch.Just sayin.

Fair enough, because I did note that was unusual.

musky1963

Quick hijack.....I just pulled the pr's from my 2.3tls. I want to get rid of the polyswitches and use jumpers. I do not see enough room to do so, as the legs on the mustard colored polys are not long enough and are very close to the board. Tight quarters, next to harness and a cap too. Do I have to remove the x-over and do it from the backside of the crossover?