Monitor 10 Crossover 4 Ohms?
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Rambler
Posts: 3
Greetings!
I picked up a pair of what appear to be early Monitor 10s. I'm in the middle of refurbishing them. The original peerless tweeters were DOA. I was able to purchase a used pair of peerless tweeters from ebay but they are not polks. The 6.5s are silver baskets with no label on the magnet.
The tweeters read 8 ohms. The 6.5s read 6.6 ohm. I got everything connected on the bench and I'm getting 4 ohms at the terminals. Did I do something wrong? Is this correct? Everything plays when hooked up to a receiver. I have been reading they should be 6 ohms.
Capacitors are ClarityCaps one 12uF and one 33uF per crossover
Resistors are Mundorf 2.7 ohm two per crossover
Inductors were reused.
This crossover does not follow any schematics I found on this site. I did not see any polarity markings on the capacitors or resistors and quick search said it should not matter. The cabinets are not done so I am still waiting to put everything back together.
Are my crossovers fine? Were the tweeters supposed to be 4ohm? Just put it together any play them? Any advice is appreciated. I know enough to be dangerous with a soldering iron and read a schematic but after that i'm lost.
Thanks
I picked up a pair of what appear to be early Monitor 10s. I'm in the middle of refurbishing them. The original peerless tweeters were DOA. I was able to purchase a used pair of peerless tweeters from ebay but they are not polks. The 6.5s are silver baskets with no label on the magnet.
The tweeters read 8 ohms. The 6.5s read 6.6 ohm. I got everything connected on the bench and I'm getting 4 ohms at the terminals. Did I do something wrong? Is this correct? Everything plays when hooked up to a receiver. I have been reading they should be 6 ohms.
Capacitors are ClarityCaps one 12uF and one 33uF per crossover
Resistors are Mundorf 2.7 ohm two per crossover
Inductors were reused.
This crossover does not follow any schematics I found on this site. I did not see any polarity markings on the capacitors or resistors and quick search said it should not matter. The cabinets are not done so I am still waiting to put everything back together.
Are my crossovers fine? Were the tweeters supposed to be 4ohm? Just put it together any play them? Any advice is appreciated. I know enough to be dangerous with a soldering iron and read a schematic but after that i'm lost.
Thanks
Comments
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You are just reading the midwoofer circuit when you measure resistance across the binding posts because the tweeter circuit has a capacitor in series with it and capacitors cannot pass DC current. You are getting the DC resistance of the large inductor plus the resistance of the 2 MW6500s in parallel with each other. The MW6500s should measure 6.50 Ohms each and in parallel would be 3.25 Ohms. The rest is from the inductor.
The tweeters should measure almost 8 ohms. Some that I have are lower than that but most of mine measure around 7.7 Ohms. Polk didn't use any 4 ohm nominal impedance Peerless to my knowledge.
6 ohms is the nominal impedance rating. Nominal impedance is always going to be higher than DC resistance due to inductive reactance and impedance will vary with frequency greatly.George / NJ
Polk 7B main speakers, std. mods+ (1979, orig owner)
Martin Logan Dynamo sub w/6ft 14awg Power Cord
Crown D150 amp
Logitech Squeezebox Touch Streamer w/EDO applet
iFi nano iDSD DAC
iPurifier3
iDefender w/ iPower PS
Custom Steve Wilson 1m UPOCC Interconnect
iFi Mercury 0.5m OFHC continuous cast copper USB cable
Custom Ribbon Speaker Cables, 5ft long, 4N Copper, 14awg, ultra low inductance
Custom Vibration Isolation Speaker Stands and Sub Platform -
I appreciate education. It sounds like I'm on the right track. I was worried about the tweeter because I could not test the old ones.
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I can't really read the EIA Source code but maybe it says 1056? If so the drivers were made by Gefco. The number next to that should be the date code.
As far as I can tell you are on the right track
George / NJ
Polk 7B main speakers, std. mods+ (1979, orig owner)
Martin Logan Dynamo sub w/6ft 14awg Power Cord
Crown D150 amp
Logitech Squeezebox Touch Streamer w/EDO applet
iFi nano iDSD DAC
iPurifier3
iDefender w/ iPower PS
Custom Steve Wilson 1m UPOCC Interconnect
iFi Mercury 0.5m OFHC continuous cast copper USB cable
Custom Ribbon Speaker Cables, 5ft long, 4N Copper, 14awg, ultra low inductance
Custom Vibration Isolation Speaker Stands and Sub Platform -
Better pic of magnets. Two look like 1056 to me
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The masking tape is covering up the other ones and the two that say 1056 I can't read the date codes very well. I see one of the ones with the masking tape says 43rd week of 1977.George / NJ
Polk 7B main speakers, std. mods+ (1979, orig owner)
Martin Logan Dynamo sub w/6ft 14awg Power Cord
Crown D150 amp
Logitech Squeezebox Touch Streamer w/EDO applet
iFi nano iDSD DAC
iPurifier3
iDefender w/ iPower PS
Custom Steve Wilson 1m UPOCC Interconnect
iFi Mercury 0.5m OFHC continuous cast copper USB cable
Custom Ribbon Speaker Cables, 5ft long, 4N Copper, 14awg, ultra low inductance
Custom Vibration Isolation Speaker Stands and Sub Platform -
Should have gotten the 34uF from Sonicap. It does make a difference.
Oh yeah, the short version is you're measuring the resistance not the nominal impedance.Political Correctness'.........defined
"A doctrine fostered by a delusional, illogical minority and rabidly promoted by an unscrupulous mainstream media, which holds forth the proposition that it is entirely possible to pick up a t-u-r-d by the clean end."
President of Club Polk
