Hello,
Please help me identify the components I should have in my Argonaut MkII crossovers. I bought them off someone who said they had replaced the capacitors with ClarityCaps. True but there is still a 10uF Alcap in there, perhaps because it is so much smaller. Here is the schematic.
Because the capacitors have been changed and I suspect the resistors too I'd appreciate somebody telling me what the values in the crossover should be.
HF 5.7uF and 3k ohms
LF 15uF and 3k6 ohms
look right?
Hopefully somebody knows the values or has a schematic.
thanks in advance.
Please help me identify the components I should have in my Argonaut MkII crossovers. I bought them off someone who said they had replaced the capacitors with ClarityCaps. True but there is still a 10uF Alcap in there, perhaps because it is so much smaller. Here is the schematic.
Because the capacitors have been changed and I suspect the resistors too I'd appreciate somebody telling me what the values in the crossover should be.
HF 5.7uF and 3k ohms
LF 15uF and 3k6 ohms
look right?
Hopefully somebody knows the values or has a schematic.
thanks in advance.
Last edited by a moderator:
There can't be a 3K in series with the tweeter, maybe a 3 ohm. I also doubt the 3.6K in series with the parallel caps on the woofers.
3Ω and 3.6Ω look normal. Any pics of the resistors? Are they sand cast and does the woofer shunt read 3R6?
Yes, my stupid mistake - of course that are single ohm values.
The resistors aren't the Micropride sandcast ones I see in pictures of 780 crossovers, but much smaller wirewound ones. I guess they were replaced when the capacitors were replaced.
Without extracting them from positions I can't read anything on the body. They are small and might be discoloured. I might replace them with guaranteed higher power rating anyway.
I'll update the diagram.
The resistors aren't the Micropride sandcast ones I see in pictures of 780 crossovers, but much smaller wirewound ones. I guess they were replaced when the capacitors were replaced.
Without extracting them from positions I can't read anything on the body. They are small and might be discoloured. I might replace them with guaranteed higher power rating anyway.
I'll update the diagram.
Revised diagram
Are the capacitor and resistor values the standard Mission 780 MkII values?
Are the capacitor and resistor values the standard Mission 780 MkII values?
Last edited by a moderator:
Thanks AllenB
Looks like Ricoh found the same caps values as me. Would be good to get confirmation on resistor values too.
Looks like Ricoh found the same caps values as me. Would be good to get confirmation on resistor values too.
A speaker known as an Argonaut worries me. If I know my Greek mythology, Jason was involved with Fleeces... 😀
But actually looks OK. A "Super Elliptic Impedance Transformed Tweeter" sounds like audio hoey, but an efficient waveguided tweeter might help what is a loud MTM time aligned speaker. Two 8" polycones is just screaming for a coil and some impedance correction for a 3.5kHz crossover.
Looks OK to me. Time alignment should make it positive polarity. The coils will be around 1mH on the bass, and 0.2mH on the tweeter.
I do this sort of thing myself with single bass:
There might be a case for adding a 15uF capacitor to the tweeter for third order. I wouldn't lose sleep over a 10uF Alcap on the bass. With 3.6R in series, any residual capacitor ESR will not be an issue. All looks good to me.
The Mission System Mission 780 Argonaut loudspeaker | Stereophile.com
But actually looks OK. A "Super Elliptic Impedance Transformed Tweeter" sounds like audio hoey, but an efficient waveguided tweeter might help what is a loud MTM time aligned speaker. Two 8" polycones is just screaming for a coil and some impedance correction for a 3.5kHz crossover.
Looks OK to me. Time alignment should make it positive polarity. The coils will be around 1mH on the bass, and 0.2mH on the tweeter.
I do this sort of thing myself with single bass:
There might be a case for adding a 15uF capacitor to the tweeter for third order. I wouldn't lose sleep over a 10uF Alcap on the bass. With 3.6R in series, any residual capacitor ESR will not be an issue. All looks good to me.
The Mission System Mission 780 Argonaut loudspeaker | Stereophile.com
Hello,
I have an older loudspeaker Mission 780 Argonaut, from about 1984.
The tweeter does not have a front additional horn "Double Chamber Acoustical Impedance Transformed Tweeter".
The tweeter does not have a rear additional chamber.
Unusual is the non-air damping with thick foam and only one of the bass speakers, see photo.
It has a different speaker crossover than is usually seen here.
I have an older loudspeaker Mission 780 Argonaut, from about 1984.
The tweeter does not have a front additional horn "Double Chamber Acoustical Impedance Transformed Tweeter".
The tweeter does not have a rear additional chamber.
Unusual is the non-air damping with thick foam and only one of the bass speakers, see photo.
It has a different speaker crossover than is usually seen here.
Attachments
