I thought you might find it helpful to see how this Mission 762i loudspeaker works, based on what I know about it, and you might measure some precise values:
Approximate circuit:
Guesstimate response:
Phase response (The bit that usually only I am interested in...):
Here's where some of my Boxsim 1.2 twiddling went, a circuit suitable for a SET amplifier, the middle LCR is called impedance correction, albeit I think closed box works better:
Looks like this:
That 22R and 0.68uF is called a tank notch at around 6kHz.
The dotted line is with just the 22R and positive polarity. Thus:
Boxsim 1.2 available here:
https://www.diyaudio.com/community/...-from-visaton-free.267787/page-2#post-7126272
I like it for its accurate phase calculation. I have no idea what will sound better, but favour the tank notch.
With some cheap Mundorf electrolytics, and cheap ceramic resistors. you could have endless fun experimenting. 🙂
Approximate circuit:
Guesstimate response:
Phase response (The bit that usually only I am interested in...):
Here's where some of my Boxsim 1.2 twiddling went, a circuit suitable for a SET amplifier, the middle LCR is called impedance correction, albeit I think closed box works better:
Looks like this:
That 22R and 0.68uF is called a tank notch at around 6kHz.
The dotted line is with just the 22R and positive polarity. Thus:
Boxsim 1.2 available here:
https://www.diyaudio.com/community/...-from-visaton-free.267787/page-2#post-7126272
I like it for its accurate phase calculation. I have no idea what will sound better, but favour the tank notch.
With some cheap Mundorf electrolytics, and cheap ceramic resistors. you could have endless fun experimenting. 🙂
I have been working on old Mission 770s recently. They were remarkably good in their day and still put a up a very good show nowadays if in good condition. The thin wall concept can work well but the amount of bituminous panel damping originally fitted is minimal. There are better lossy materials than carpet to add some mass damping but that is a good start. There is no need to remove the original damping just staple through it. The speakers should actually feel heavier when properly mass damped.
Look out for loose flappy rubber surrounds where the glue has failed. Also several pairs for reworking have been found to have their connection terminals pulled off at the drive unit. The wire gauge would support welding (!) and is excessive for the strength of the terminals. With care machine screws screws, plastic insulators and solder tags can remake broken terminals. Soldering needs to be done quickly to the Litz leads from the voice coil. Avoid solder droplets going through the cone . I agree that nothing needs doing to the crossovers, Don't be tempted to go for air cored inductors it is impractical. It is easier and it sounds better to make them active. I may try and make some flared ports to upgrade the old ones.
My son has the new 770s. They are extremely clean and are effortless even at high levels. He will be deaf before the year is out, He regularly clips the amp with 150W peaks.
Look out for loose flappy rubber surrounds where the glue has failed. Also several pairs for reworking have been found to have their connection terminals pulled off at the drive unit. The wire gauge would support welding (!) and is excessive for the strength of the terminals. With care machine screws screws, plastic insulators and solder tags can remake broken terminals. Soldering needs to be done quickly to the Litz leads from the voice coil. Avoid solder droplets going through the cone . I agree that nothing needs doing to the crossovers, Don't be tempted to go for air cored inductors it is impractical. It is easier and it sounds better to make them active. I may try and make some flared ports to upgrade the old ones.
My son has the new 770s. They are extremely clean and are effortless even at high levels. He will be deaf before the year is out, He regularly clips the amp with 150W peaks.
