collinTHEbrewer
Active member
- Joined
- Jul 29, 2013
- Messages
- 35
Here goes another Yamaha mixer thread...
I got a pretty clean Yamaha M512 from a local shop, and I thought I'd consider using it as a vibey preamp option. 12-channels of cheap-ish input transformers sounded like a fun deal to me especially for drums. I had an old RAMSA mixer years ago that I used for a similar thing, but the size was a little ridiculous. This is a lot more compact and could easily be put away when not in use.
So here's what I'm thinking:
-Add balanced outputs
-Swap Preamp TA7322P opamps (IC1, IC2)
-Recap
-Tweak EQ frequencies
Balanced Outputs
I think I've got two main options here. Either way, I would be diverting the pre-fader FB send to a switching TRS jack. The question is, to transform or not to transform? I can either do some psuedo impedance balancing using a resistor and capacitor as described by Jensen (https://www.jhbrandt.net/wp-content/uploads/2014/11/Interconnection_of_Balanced_and-Unbalanced-Equipment.pdf), or I could add in some OEP A262A2E transformers. One is obviously way cheaper than the other, but I did find a good deal on a dozen OEP transformers.
Opamp Swap
The TA7322P is a real pain. For starters, it's a single opamp in a 9-pin SIP package that runs on a +-25VDC supply.
Problem #1 - SIP Package
There are some solutions/adapters that will fit the SIP pinout and adapt to something like a OPA604 or similar. The most common solutions are fairly pricey (~$4 per adapter x 2 x 12 = $$$).
Problem #2 - Supply Voltage
Most modern opamps won't tolerate more that +-18VDC. I was thinking I could throw in a pair of 7.5V zener diodes to each opamp to lower it down closer to 18V.
Problem #3 - Inventory
I have about 20 LME49720 dual opamps laying around, and I'm thinking that sounds cheaper than 24 new single opamps. However, I would need to figure out an adapter solutions that could potentially utilize both channels of the LME49720.
Recap
I only count about half a dozen electrolytic caps touching the the signal path between the input and fader. Any reason to replace any others?
EQ Frequencies
Without getting to use this in a session yet, I have no idea what to expect from the EQs, but the word on the web is that they could use some love. (https://groupdiy.com/index.php?topic=51214.0)
Anyone have any thoughts or see any red flags?
I got a pretty clean Yamaha M512 from a local shop, and I thought I'd consider using it as a vibey preamp option. 12-channels of cheap-ish input transformers sounded like a fun deal to me especially for drums. I had an old RAMSA mixer years ago that I used for a similar thing, but the size was a little ridiculous. This is a lot more compact and could easily be put away when not in use.
So here's what I'm thinking:
-Add balanced outputs
-Swap Preamp TA7322P opamps (IC1, IC2)
-Recap
-Tweak EQ frequencies
Balanced Outputs
I think I've got two main options here. Either way, I would be diverting the pre-fader FB send to a switching TRS jack. The question is, to transform or not to transform? I can either do some psuedo impedance balancing using a resistor and capacitor as described by Jensen (https://www.jhbrandt.net/wp-content/uploads/2014/11/Interconnection_of_Balanced_and-Unbalanced-Equipment.pdf), or I could add in some OEP A262A2E transformers. One is obviously way cheaper than the other, but I did find a good deal on a dozen OEP transformers.
Opamp Swap
The TA7322P is a real pain. For starters, it's a single opamp in a 9-pin SIP package that runs on a +-25VDC supply.
Problem #1 - SIP Package
There are some solutions/adapters that will fit the SIP pinout and adapt to something like a OPA604 or similar. The most common solutions are fairly pricey (~$4 per adapter x 2 x 12 = $$$).
Problem #2 - Supply Voltage
Most modern opamps won't tolerate more that +-18VDC. I was thinking I could throw in a pair of 7.5V zener diodes to each opamp to lower it down closer to 18V.
Problem #3 - Inventory
I have about 20 LME49720 dual opamps laying around, and I'm thinking that sounds cheaper than 24 new single opamps. However, I would need to figure out an adapter solutions that could potentially utilize both channels of the LME49720.
Recap
I only count about half a dozen electrolytic caps touching the the signal path between the input and fader. Any reason to replace any others?
EQ Frequencies
Without getting to use this in a session yet, I have no idea what to expect from the EQs, but the word on the web is that they could use some love. (https://groupdiy.com/index.php?topic=51214.0)
Anyone have any thoughts or see any red flags?