JW
Well-known member
Hey folks,
So I built this little mini mixer out of extra yamaha parts that I had acquired over the years (it can actually be 8X2 or split apart as two 4X1's) Works as it should. Has direct outs on every channel in the same fashion by which people are racking up the strips. That is, directly from capacitor C37 to the 600:600 output transformer. At the same time, any of the input strips can feed the 2 master outs or the aux strip as well.
As many people have found, these sound pretty fat on drums and loud stuff, but there's not all that much gain for more quiet sources. When you crank the input switch all the way up, it starts to sound quite thin and nasty driving the output transformer in direct out fashion. (Not when you use the master out, as there is definitely the required gain there)
Anyway, in the interest of having my cake and eating it too, I was thinking that rather than doing things to the input strips to get extra gain, such as bypassing the fader, or adjusting the feedback, it might be a better idea to leave the input strips like they are, and build out the extra amp stage that is present in the master strips, and put it between C37 and the direct out transformers on every channel. Actually, C37 would be driving both this extra stage into direct out, AND going into the master channels at the same time. I don't think this would be a problem, but maybe I'm wrong? . . .
I'm attaching zoom in snap shots of these parts of both the input and master strip schematics to clarify. Notice the 4 transistor amplification stage is almost identical in both the input strip and the master strip with the exception of R14 (12K) and R17 (4.7K trimmer) in the master strip not corresponding to R60 (4.7K) and R61 (10K trimmer) in the input strip.
For the full schematics, they are in the technical documents here: http://groupdiy.com/index.php?topic=44874.0 Input strip in the first post, master strip in the last post.
I have all the transistors already. This would be a pretty cheap solution.
My questions are,
1. Will this work? Am I going to encounter something funky about the input strips driving both the master section and a parallel direct out with 4 more transistors? Seems not because that's what it's doing in the original console anyway correct?, actually driving 4 master strips.
2. Is it just a matter of hanging C7 (master strip line input) on the output of C37 (input strip output?)
3. There is 1 diode in the circuit. What should I use for that? Is says STV-3.
4. What should I do about the 4.7K trimmer in the master out circuit? How to trim? . . .
So I built this little mini mixer out of extra yamaha parts that I had acquired over the years (it can actually be 8X2 or split apart as two 4X1's) Works as it should. Has direct outs on every channel in the same fashion by which people are racking up the strips. That is, directly from capacitor C37 to the 600:600 output transformer. At the same time, any of the input strips can feed the 2 master outs or the aux strip as well.
As many people have found, these sound pretty fat on drums and loud stuff, but there's not all that much gain for more quiet sources. When you crank the input switch all the way up, it starts to sound quite thin and nasty driving the output transformer in direct out fashion. (Not when you use the master out, as there is definitely the required gain there)
Anyway, in the interest of having my cake and eating it too, I was thinking that rather than doing things to the input strips to get extra gain, such as bypassing the fader, or adjusting the feedback, it might be a better idea to leave the input strips like they are, and build out the extra amp stage that is present in the master strips, and put it between C37 and the direct out transformers on every channel. Actually, C37 would be driving both this extra stage into direct out, AND going into the master channels at the same time. I don't think this would be a problem, but maybe I'm wrong? . . .
I'm attaching zoom in snap shots of these parts of both the input and master strip schematics to clarify. Notice the 4 transistor amplification stage is almost identical in both the input strip and the master strip with the exception of R14 (12K) and R17 (4.7K trimmer) in the master strip not corresponding to R60 (4.7K) and R61 (10K trimmer) in the input strip.
For the full schematics, they are in the technical documents here: http://groupdiy.com/index.php?topic=44874.0 Input strip in the first post, master strip in the last post.
I have all the transistors already. This would be a pretty cheap solution.
My questions are,
1. Will this work? Am I going to encounter something funky about the input strips driving both the master section and a parallel direct out with 4 more transistors? Seems not because that's what it's doing in the original console anyway correct?, actually driving 4 master strips.
2. Is it just a matter of hanging C7 (master strip line input) on the output of C37 (input strip output?)
3. There is 1 diode in the circuit. What should I use for that? Is says STV-3.
4. What should I do about the 4.7K trimmer in the master out circuit? How to trim? . . .
