Monitor 10B Crossover question.

Blacksoldier

Hi guys,
I have a question that I am sure someone here will be able to help me with. I am in the process of restoring a pair of monitor 10's. They have the MW6503 drivers and the SL2000 tweeters. Based on a couple other threads and my research, I ordered (4)-12uF caps, (2)-33uF cap, and 4 Mills 2.5 ohm resistors (since I could not find a 2.7 ohm one, and I was informed that the 2.5 would work).

Now..here is the problem. When I started to remove the caps and resistors from the crossover, I noticed that their is a 2 ohm resistor in parallel with the 12uF, 50VNP resistor instead of a 2.7ohm one. So...my question is, could I still use the 2.5 ohm mills or do I need to reorder 2- 2ohm mills resistors?

Thanks for all your help.

BS

Blacksoldier

Here is how the cap and the resistor were mounted in the crossover. Is that in parallel or series? I also noticed on the other crossover that there are two resistors with the 12uf cap. Both resistors are mounted on top of each other and the top one says 4ohms. Was Polk trying to make up a value? Thanks for any and all replies.

BS

westmassguy

So you have a pair of 10s with different crossovers correct? Not unheard of. Were the two stacked resistors both 4 ohms? If so, and they were wired in parallel, that would equal a 2ohm 10 watt resistor. Do your 10s have fuses or polyswitches? It's always good practice, to check what's actually on your crossover board, rather than relying on what others wrote about, or even what the schematics say should be there. I'll help as best I can

Blacksoldier

westmassguy wrote: »

So you have a pair of 10s with different crossovers correct? Not unheard of. Were the two stacked resistors both 4 ohms? If so, and they were wired in parallel, that would equal a 2ohm 10 watt resistor. Do your 10s have fuses or polyswitches? It's always good practice, to check what's actually on your crossover board, rather than relying on what others wrote about, or even what the schematics say should be there. I'll help as best I can

Thanks for the quick reply westmassguy. I am not sure if the two stacked resistors are 4 ohms, since they are my reference while I upgrade the other one, maybe they are. My monitor 10's have polyswitches which I was not going to replace, but thought about cutting off the tips and resoldering the bare wire together again as per a few threads I have seen here on the subject. I appreciate any help you can provide. Thanks again.

BS

westmassguy

Blacksoldier wrote: »

Thanks for the quick reply westmassguy. I am not sure if the two stacked resistors are 4 ohms, since they are my reference while I upgrade the other one, maybe they are. My monitor 10's have polyswitches which I was not going to replace, but thought about cutting off the tips and resoldering the bare wire together again as per a few threads I have seen here on the subject. I appreciate any help you can provide. Thanks again.

BS

I would not recommend just jumping them out, which is what you're talking about. The SL2000s are painful enough to listen to with the resistance of the Polyswitch. You need a .5 ohm Mills in place of it. The 2.7 ohm resistor in series with the inductor, is critical, and will affect the voicing of the tweeter. I would contact Eric over at Sonicraft, he'll get you squared away with the various values you need. You need two each .5 ohm, two each 2.0 ohm, and two each 2.7 ohm.

Blacksoldier

westmassguy

There are no 2.7 Ohm resistors in my crossovers, only a 2.5 Ohm 10% 5W, plus the 2.0 Ohm one which is in series I presume with the 12 uF capacitor.

westmassguy

Blacksoldier wrote: »

westmassguy

There are no 2.7 Ohm resistors in my crossovers, only a 2.5 Ohm 10% 5W, plus the 2.0 Ohm one which is in series I presume with the 12 uF capacitor.

Your first post said "4 Mills 2.5 ohm resistors (since I could not find a 2.7 ohm one, and I was informed that the 2.5 would work)"
The schematics all show a 2.7 ohm in series with the small inductor (bypass). They show a 2.0 ohm in parallel with one of the 12uf caps.
You're telling me neither of the crossovers have that arrangement?

Blacksoldier

westmassguy wrote: »

Your first post said "4 Mills 2.5 ohm resistors (since I could not find a 2.7 ohm one, and I was informed that the 2.5 would work)"
The schematics all show a 2.7 ohm in series with the small inductor (bypass). They show a 2.0 ohm in parallel with one of the 12uf caps.
You're telling me neither of the crossovers have that arrangement?

Sorry for the confusion, I had originally made that post based on what I saw online before checking my crossover. Sorry for not editing my original post when I discovered the discrepancy. Correct, neither of my crossovers have that arrangement. One has a 2.0 Ohm,10% 5W with the 12Uf Cap, and a 2.5 Ohm 10%, 5W resistor by itself. The other has a 2.5 Oh, 10%, 5W by itself, and what could possibly be 2, 4.0 Ohms 10%, 5W resistors in parallel as you suggested along with the 12uF Cap.

westmassguy

Blacksoldier wrote: »

Sorry for the confusion, I had originally made that post based on what I saw online before checking my crossover. Sorry for not editing my original post when I discovered the discrepancy. Correct, neither of my crossovers have that arrangement. One has a 2.0 Ohm,10% 5W with the 12Uf Cap, and a 2.5 Ohm 10%, 5W resistor by itself. The other has a 2.5 Oh, 10%, 5W by itself, and what could possibly be 2, 4.0 Ohms 10%, 5W resistors in parallel as you suggested along with the 12uF Cap.

No worries. If you want to just use what you have, the 2.5 in place of the 2 should be OK, just be sure to jump out the polyswitch. The total resistance going forward will be about the same, but no telling what the interaction will be with the 12uf in parallel. I doubt you'll notice any difference.

Blacksoldier

westmassguy wrote: »

No worries. If you want to just use what you have, the 2.5 in place of the 2 should be OK, just be sure to jump out the polyswitch. The total resistance going forward will be about the same, but no telling what the interaction will be with the 12uf in parallel. I doubt you'll notice any difference.

Ok Thanks. So based on the pic I posted showing how the 12uF cap and the 2 ohm resitor were soldered in the crossover, is that what it looks when its in parallel? Also, just to be sure, cutting off the end of the polyswitch and soldering the endes together is ok then? If I do decide to get the .5 ohm and the 2.0 Ohm resistors, I should remove the polyswith and replace it with the .5 ohm and use the 2.0 ohm since that was already in the crossover?

Thanks again, you have been a great help.

westmassguy

Blacksoldier wrote: »

Ok Thanks. So based on the pic I posted showing how the 12uF cap and the 2 ohm resitor were soldered in the crossover, is that what it looks when its in parallel? Also, just to be sure, cutting off the end of the polyswitch and soldering the endes together is ok then? If I do decide to get the .5 ohm and the 2.0 Ohm resistors, I should remove the polyswith and replace it with the .5 ohm and use the 2.0 ohm since that was already in the crossover?

Thanks again, you have been a great help.

Correct on all points. It would be better to just de-solder the polyswitch, and put a small jumper wire in it's place. You'll have plenty of small lengths once you trim off the bottom of the caps after soldering.

Blacksoldier

Ok thanks again westmassguy, you are the man. hey another question. I had posted it in an older post I had about my MW6503 drivers but Ill ask since you are replying so quickly to my posts here...lol. Where would I get a rubber surround that has separated from the cone on my MW6503 driver/ Thanks again.

BS

Blacksoldier

Sorry Westmassguy, I did not realize the post was being answered in the thread meant for it. I will post the pic of the driver in that thread instead.

StantonZ

I had a similar question when I first looked at schematics and thought about rebuilding my 10B crossovers. My conclusion at that time was: get rid of the polyswitch and use a 2.5 ohm resister (instead of 2.0). I'm almost afraid to measure the resistance of the polyswitch since it's so old: I know if I do I'll probably want to mod the crossovers immediately!