Hi folks... I've owned this Yamaha CA-610 II since 1998. I purchased it at a yard sale in Grand Forks N.D. It works perfect.
Here is what I want to do...
1. Replace the Amplifier Section with a pair of L20SE's or similar.
2. Replace the pre-amp section with a combination of Elliott Sound project 97 but use all the functions and controls as in the Volume/Balance/Loudness...Exc.
It looks like the Factory Pre-Amp has little to no gain as seen if the Direct switch is On.
I have no problem doing mods to electronics, been doing it for about 40 years.
I've put together what I think would work but wanted to get thoughts or opinions from other members as I'm NOT an engineer.
Biggest reason for doing this is none of the semiconductors are available from a trusted source.
I suppose I could bread board it to make sure but thought I'd ask.
Thanks all...
Here is what I want to do...
1. Replace the Amplifier Section with a pair of L20SE's or similar.
2. Replace the pre-amp section with a combination of Elliott Sound project 97 but use all the functions and controls as in the Volume/Balance/Loudness...Exc.
It looks like the Factory Pre-Amp has little to no gain as seen if the Direct switch is On.
I have no problem doing mods to electronics, been doing it for about 40 years.
I've put together what I think would work but wanted to get thoughts or opinions from other members as I'm NOT an engineer.
Biggest reason for doing this is none of the semiconductors are available from a trusted source.
I suppose I could bread board it to make sure but thought I'd ask.
Thanks all...
Attachments
Definitely needs some changes to work, just glancing at it.
Also you need to specify the type of op amps, and whether single supply or dual supply.
They will have to be unity gain stable types.
You should breadboard it anyway. Use a solderless breadboard
and the parts won't get mangled or soldered.
Also you need to specify the type of op amps, and whether single supply or dual supply.
They will have to be unity gain stable types.
You should breadboard it anyway. Use a solderless breadboard
and the parts won't get mangled or soldered.
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One example, just before the high filter you need a series resistor to make the filter work.
Something like 6.8k.
The first op amp will have a problem with the high value 200k volume control.
The power amp input impedance is 12k, rather low for that 200k balance control.
Direct mode would load the 200k volume control too heavily.
And the output capacitor would have to be more like 10uF.
Could you change the volume and balance controls to 10k?
Something like 6.8k.
The first op amp will have a problem with the high value 200k volume control.
The power amp input impedance is 12k, rather low for that 200k balance control.
Direct mode would load the 200k volume control too heavily.
And the output capacitor would have to be more like 10uF.
Could you change the volume and balance controls to 10k?
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Project 97 uses 100k for volume and 50k for balance but I know this design is from 1977!! So to go forward, I would have to get 10k pots... I'll have to take the Volume/balance assembly out of the stereo and see if they can be changed.
Thanks much for looking at this.
Those are bipolar so you'll need DC-blocking cap on the volume pot wiper, and another route for input bias currents. Unless you like crackling on the volume control.
Are you talking about the 5532 are bipolar? So the DC blocking should be 10uf? And where would the other route for bias current be placed?
Sorry for the questions but I'm glad you pointed this stuff out.
One more question... The original circuit with the three transistor, (that can't be purchased anymore), is there a way I could replace them with similar values, maybe use lower voltage supply? Just curious.
Thanks much...
> three transistor, (that can't be purchased anymore),
R.G.'s Law. When in doubt, use 2N5089 and 2N5087.
This is vanilla design. Does not need "magic" parts. The Yamaha part numbers may have been speced for OK performance at very low cost or deep availability (at the time).
R.G.'s Law. When in doubt, use 2N5089 and 2N5087.
This is vanilla design. Does not need "magic" parts. The Yamaha part numbers may have been speced for OK performance at very low cost or deep availability (at the time).
This is because of the low input impedance (12k) of the power amp you want to use.