I ran with the resistor chain current stabiliser... I wasn’t keen on the existing current stabiliser... in fact that may well be the cause of failure.... similar array wreaked havoc on V4X amps
Those who wonder.... same power ic in Z600 Z610 Z650 V66 X90 - never see those have current stabiliser dramas they present danger to the power ic
Ok I see what you're doing (don't totally got it but just enough to understand the concept).
I think if I do this for my friend it will have to be on a budget so I'll probably bypass the whole pcb idea and connect the components directly between pins/wires.
I think if I do this for my friend it will have to be on a budget so I'll probably bypass the whole pcb idea and connect the components directly between pins/wires.
If it were mine I would do it for sure, and I count on insisting he decides that too but from there it's out of my hands.
Speaking from experience here. I would pull out of the project. Otherwise everything that goes wrong will be your fault.
-Chris
-Chris
I'm having cold sweats from the beginning but he really wants to see them live again. Would you recommand getting rid of the whole amplifier part, take the output of the preamp/tone control, put in a new amplifier kit using +/-48V rails and connect the output to the protection circuit. Or even get a kit with a built in protection relay and connect directly to the speakers and power meters ? It would seem that budget wise that might not even turn out to be more expensive.
I would do what you are most comfortable with. If he doesn't want to do something the proper way, then bail on the project. Since you will be held responsible for what you do, recommended or not, you have every right to expect that you are allowed to do things in a reliable way. Otherwise ... you just can't win.
-Chris
-Chris
Words of wisdom. I'll explain both options and according to the answer will either go for the more complicated (and surely more expensive) but probably closer to the original method or the swap feast option. I'll keep you posted anyway 🙂
Ok so here's the final decision, I will swap out the whole power amplifier of the su-v4 and put a mx50se kit in its place, it will work on the existing supply rails (I will increase slightly the 2 filter caps). Only question is, as the tone controls are in the negative feedback loop, can I make them work by connecting them up like shown in the pictures ?
Hi Depaj,
I would run the tone section on an external op amp and feed the new amplifier with that. Running the amplifier feedback through a set of tone controls can have really serious issues.
-Chris
I would run the tone section on an external op amp and feed the new amplifier with that. Running the amplifier feedback through a set of tone controls can have really serious issues.
-Chris
Is it as simple as you make it sound or does this involve a whole lot of modifications ? The tone control here seems to use a dc servo amp that confuses me a little bit.
Simple? Depends on your experience. A piece of vero board would do. Use an NE5532 or similar.
A feedback type tone control circuit in the feedback network of a power amplifier can make it conditionally unstable. PITA to figure out, so if you can avoid this all together, do it. A tone control that is separate is a much cleaner way to create a tone control.
If you need a schematic, just search some preamplifiers and you should be able to find one.
-Chris
A feedback type tone control circuit in the feedback network of a power amplifier can make it conditionally unstable. PITA to figure out, so if you can avoid this all together, do it. A tone control that is separate is a much cleaner way to create a tone control.
If you need a schematic, just search some preamplifiers and you should be able to find one.
-Chris
So I will have to build a new one, I can't use the existing one ?
My experience with building is extremely limited, I've been repairing and restoring a lot and Am currently working on my first complete project but for the most part it's based on existing designs.
My experience with building is extremely limited, I've been repairing and restoring a lot and Am currently working on my first complete project but for the most part it's based on existing designs.
Hi Depaj,
Just copy it from another piece of equipment. You can read schematics and that's a big hurdle out of the picture. It should be fairly straight forward.
-Chris
Just copy it from another piece of equipment. You can read schematics and that's a big hurdle out of the picture. It should be fairly straight forward.
-Chris
It's not the copying that's worrying me, I got quite good at that 😀 , it's the whole bunch of new parts I will have to get plus the pcb to order or the extensive modification I will have to bring to the existing board. Also the amp seems to have an active tone control with IC 303 as the tone amp, does this change anything ?
Last edited: