Using 2 mw6503's with peerless tweeter...Which crossover?

jakelm

Hi all. Its been a while since I've visited. I'm glad to be back.

I have 2 mw6503's and a peerless tweeter....I currently have 7b's with peerless as left and right channel and I'm thinking of building a center channel with the 2 mw6503's and the peerless to complement the 7b's. The crossovers in mind or the ones used in the 10's. Polk has 2 different crossovers, one is for 10b and the other for 10 series 2. I was wondering whch would be best for me mw6503's as a center channel?

M10B BE1000-A $46.40 ?
M10 SER 2 BE1000-B $49.60 ?

Now the mw6503 was used in both the 10B and the series 2, but the peerless wasnt. So my question again is with both the mw6503 and the peerless which would be best?

Thanks
Jake

P.S. I did post this in the vintage section, but since this is a DIY job, I figure it would go here too. I appologize for the multipost.

schwarcw

Jake,

Use the crossover that was designed to play with the Peerless tweeter. This will be you most critical timbre match. Sounds like a cool project. Are you going to use a passive radiator in you custom center? Good luck and let us how how it sounds.

jakelm

Thanks Carl

No.This center channel is designed without the low end of a PR. In stead a tuned port will be used. The problem I have is that I cannot find an original Monitor 10 crossover that was used with the peerless. So my other option is to purchase a new one from polk. My guess (or my hope, I should say) is that the crossovers did not change much between the series. The crossover points should be pretty close. So with no luck finding the excact xover, I was hoping from the 2 choices Polk offers, someone would know the best guess.

Im hoping (if I get the encloser right) that the tember match would be closer than anything out there on the market. The trickiest part is going to be the tuning port. I think I will build different lengths and try them out and see which comes closest to the 7b's. I might not need a port at all. But we will see.

Jake

schwarcw

Hi Jake!

Checkout this link on the Forum http://www.polkaudio.com/forums/showthread.php?t=38755

This thread shows the schematic for the Polk Monitor 10's with and without the Peerless. Compare the two schematics for the crossover with the 6503 driver. Use the cap, resistor and inductor (coil) values for the 6503 and the same from the other schematic for the Peerless. You can then select a crossover from Polk that would require the least modification to match your Polk center "hybrid". The other thing to figure out is how to match the cabinent volume. You may have to build a deeper cabinent to maintain the volume needed for your design. Call Polk Customer Service and talk with Ken Swauger. He will give you some sound guidance.

Carl

jakelm

24"w x 8.25"h x 12.5d Which I beleive with a proper port will sound excellent.

The crossover are more different than I thought.

Im trying to figure out the xover point for the tweeter. Seems like the original xover allowed the peerless to handle lower hz. Or is it the opposit. I think I will get the 10B xover and see how it sounds. Unless some one knows of a 10 or 10A xover avaliable.

Jake

jakelm

Well this puts a damper on things......Polk does not handle the 10b or 10series 2 xovers anymore....I really didnt want to have to build one. Ah well..here goes nothing.

Jake

schwarcw

Hi Jake! All is not lost there are not a whole lot of components to the crossover you need. As I mentioned, pick out a crossover from the link that most resembles your design. Parts Express or any company can supply a board, binding posts, inductors, caps and resistors. Good luck! Keep us posted!

jakelm

OK just finished the box...Talk about polkenstien!!.:D .lol.. but it sounds great...I ended up with 22"w x 8.5"h x 12"d with a 2" port approx 7" long on the back side. This box is huge compared to my CS1. Just found an original m10 xover with the fuse on ebay....bought it...hope it works. I'm using my Monitor30 xover for the time being and it sounds awsome. Big difference in the peerless tweeter compared to the other dome tweeter in my CS1 center. The vocals in the center just seem to be more natural. The only thing I'm having trouble with is finding a grill to cover the front. I'll have to biuld one, I dont know how that will come out. I painted it a rot iron grey, same color as my Mitsubishi, but will venner it as soon as I can. You cant tell with the lights out but a grill and veeneer are my next step, after I install the xover.

Jake

jakelm

http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&item=250010365116

Thats what I found on ebay

Jake

jakelm

Just ordered a grill kit from partsexpress. Now once I have the grill up..you think it would upset people if I slapped a polkaudio logo on it...lol

Jake

Polk65

Excellent project. The RTA 8 / RTA 8TL are worth considering for a vintage center with port. RTA 8 - http://polksda.com/rta8t.shtml

Was this a lucky bid on your part? Looking over the schematics posted by Doro this appears to (my eyes) the correct crossover for the HF1000 or Peerless tweeter. More at post #33:
http://www.polkaudio.com/forums/showthread.php?t=32671

jakelm

If my memory serves me right, the xover with the fuse was the same xover used with the peerless. And what led me to believe also with this xover was the 12uf cap. 2 12uf caps were used with the peerless.

jakelm

Polk65, thats pretty much what I build, except for the peerless instead of the silk dome and the width (if layed sideways) is not as long (22"w), the port is in the back.

Jake

jakelm

Just installed the m10 crossover...works well. The speaker now seems alot brighter. I'm not sure if its a good thing or a bad thing. No distortion or anything just brighter.

I hope I got the wires right. White is negative? Black is positive?

Jake

jakelm

I'll try to take some pics.

Jake

Polk65

The black wires connect to the terminals with a red dot. Blue wires are the counterpart for SDA dimensional drivers.

The crossovers are different. A photo of your 7 crossover may help with suggestions of what to change. I have some spare crossover parts that I can send if you or a friend can solder.

jakelm

Polk65 wrote:

The black wires connect to the terminals with a red dot.

Thanks Polk65: I asssume you mean (red dot) is positive. So black is positive. My mw6503's are labeled +/-.

Another thing. I noticed on the schem of the m10 that the midwof (mw6501's) are ran in parallel with each other not series. But would this be the same for the mw6503's since the mw6503's ohms have changed alitlle. My understanding is the ohms on the newer mw6503 is a tad lower. Should I keep it in parallel (positive to positive, negative to negative)?

Thanks
Jake

Polk65

+ or red dot goes to the black wires. That m10 crossover is designed for drivers in parallel so keep it that way. Getting your center crossover design closer to your mains is what to aim for. From looking at the schematics, I think the issue is in the tweeter circuit. Post a pic of your crossover if you can.

jakelm

The crossover is here... My understanding from the scem is the tweeter wires come from the 12uF cap (left of xover from pic) black= pos and white= neg. And midwoofer wires come off the side(or top in pic) again black=pos and whit= neg. Correct?

jakelm

This is the current wire config...excuse the bad drawing

jakelm

Polk65 wrote:

schematics posted by Doro this appears to (my eyes) the correct crossover for the HF1000 or Peerless tweeter. More at post #33:
http://www.polkaudio.com/forums/showthread.php?t=32671

Polk65: I just read again what Ken had to say between the m10a xover and the 10b xover. My undertsanding of the schem of my xover is that it is a 10a with a 2.5ohm resistor. I still dont understand why it seems so much brighter than my 7b's, the tember especially in the higher fr should be very close to one another. Could I replace it with a 3ohm to smoothin it out even more? Or am I looking at the wrong thing?

Unless its the output of my reciever for the center channel.

Jake

jakelm

Ok now I'm confused on something. The original 10's and the original 7's had the peerless tweeter, correct?

On the schematics of the original 7's there is a 2.0 ohm resistor with the 12uF cap. There is a 2.5ohm resistor with the 12uF cap on the original 10's. Now if there is the same peerless, why is there different resistors?

I'm listening to my 7's compared to the the center I built, right now. There is a major difference in the highs. The highs in the center with the 2.5ohm resistor is alot louder than the 7's (and less mid). Now I did not pull the xover out of the 7's but I'm pretty sure is the original, because of the fuse in the back. To my knowlege there is only one style crossover with the fuse (the original). The others are revised and different generations.

Whats going on?

Jake

Polk65

The original 10's and the original 7's had the peerless tweeter, correct?

Yes. Check out brochure #2 1984 Original Monitor 7/10 Brochure (836K)

On the schematics of the original 7's there is a 2.0 ohm resistor with the 12uF cap. There is a 2.5ohm resistor with the 12uF cap on the original 10's. Now if there is the same peerless, why is there different resistors?

I suppose the 2.5 value is used to tame the tweeter down a notch since the midrange has gained sensitivity with the addition of another driver.

I'm listening to my 7's compared to the the center I built, right now. There is a major difference in the highs. The highs in the center with the 2.5ohm resistor is alot louder than the 7's (and less mid). Now I did not pull the xover out of the 7's but I'm pretty sure is the original, because of the fuse in the back. To my knowlege there is only one style crossover with the fuse (the original). The others are revised and different generations.

In the photo of your Monitor 10 crossover, resistor (B) is clearly 2.7 ohms. Resistor (A) is hard to read. Is this 2.5 ohms or 2.0 ohms? If it's 2.0 this would make the Peerless overly bright. There were several changes and part substitutions. Don't assume that your Monitor 7 crossovers match the posted schematics.

In the other thread, Ken mentioned that the tweeter will be brighter with a 2.0 ohm resistor versus 2.5 ohms. While looking over some other monitors which used Peerless tweeters I noticed that 2.7 ohm resistors were used. Try swapping the 2.5 ohms resistor (A) with 2.7 ohms resistor (B). This will tame the tweeter a notch and should wake up the mids.

I'm learning from this and starting to enjoy this project. If I make mistakes hopefully you or someone else will catch it.

jakelm

Polk65 wrote:

Is this 2.5 ohms or 2.0 ohms?
.

It is 2.5ohms.

jakelm

What if I leave the 2.7 where it is (B). And just replace the 2.5ohm (A) with a 2.7. What I will do is pull the xover out of one of my 7's and see what size resistor. If its the same, I will try swapping tweeters from my 7's to my center and see if its the driver. If it isnt the tweeter then I will try swapping the 2.5 ohm resistor with a 2.7 ohm.

jakelm

Polk65 wrote:

I suppose the 2.5 value is used to tame the tweeter down a notch since the midrange has gained sensitivity with the addition of another driver.

Why would the tweeter be tammed a notch when more bass is added? Seems it would be the oposite, with increasing the highs to keep it flat with the mids and lowes.

jakelm

I do have this hooked up right , do I? The tweeter comming of the 12uF (D) and the mids coming of the 34uF (F)?

Polk65

My understanding from the scem is the tweeter wires come from the 12uF cap (left of xover from pic) black= pos and white= neg. And midwoofer wires come off the side(or top in pic) again black=pos and whit= neg. Correct?

The wires from the yellow 12uF Mylar cap (D) go to the tweeters. Black is positive (+) red dot for both.

What if I leave the 2.7 where it is (B). And just replace the 2.5ohm (A) with a 2.7. What I will do is pull the xover out of one of my 7's and see what size resistor. If its the same, I will try swapping tweeters from my 7's to my center and see if its the driver. If it isnt the tweeter then I will try swapping the 2.5 ohm resistor with a 2.7 ohm.

That's a good plan but I hate solder fumes.

Why would the tweeter be tammed a notch when more bass is added? Seems it would be the oposite, with increasing the highs to keep it flat with the mids and lowes.

This depends on the mid-woofer driver(s) sensitivity. I don't know the driver specs but after combined, they could be more sensitive than the tweeter. The rule I believe is, when two 8ohm drivers are connected in parallel they have a combined gain of 6 dB. Let's say the tweeter is rated at 92 dB, and the mids are each 88 dB. With one mid you would want to tame the tweeter. Combining the mids in parallel increases their sensitivity so in this example, two mids rated at 88 dB would increase to around 94 dB so you would want to tame them.

jakelm

Polk65 wrote:

This depends on the mid-woofer driver(s) sensitivity. I don't know the driver specs but after combined, they could be more sensitive than the tweeter. The rule I believe is, when two 8ohm drivers are connected in parallel they have a combined gain of 6 dB. Let's say the tweeter is rated at 92 dB, and the mids are each 88 dB. With one mid you would want to tame the tweeter. Combining the mids in parallel increases their sensitivity so in this example, two mids rated at 88 dB would increase to around 94 dB so you would want to tame them.

If the 7's have the peerless and the resistor is 2.0. The xover I have for my center has a 2.5ohm resistor, wouldnt that make the peerless in the center "softer" than the peerless in the 7's, not brighter?

Thats what confuses me, my center has a larger ohm resistor, yet a brighter tweeter.

I'm saying this yet without pulling my 7's xover, to make sure. (At this point I'm assuming about the resistor on my 7's).

I have never heard the 10's personally. With the same driver, are they normally brighter than the 7's?

jakelm

Of wait a minute here....just noticed something.....

On the specs of the original 7's,,,,If you look at the notes at the bottom right. It states " 'A' : 2.0ohm was 2.7ohm; deleted"

I might have a 2.7ohm in my 7's

that would make since for the reason I have a brighter center chanel

jakelm

What I need to do is pull the 7's crossover and make sure they are the same...If they are not, I will put the same xover in the center as are in the 7's