Hi guys, I decided to mount my EF3-4 (V. 4) boards parallel to the heat sinks in the diyaudio 5U chassis. Watching Daniel's video I saw that he turned one board upside down. This results in the output transistors toward the top plate of the chassis for one channel and the output transistors are toward the bottom of the chassis for the other channel. Doing this allows you to keep the connections to the inputs/outputs for both channels short.
Because adjustable resistors R11, R25 and R109 have side adjustment screws, you need to have them facing up. Since one board is flipped around, the Bourns pots on that board are flipped around to keep the adjustment screws facing up.
I suppose the midpoint is the midpoint regardless of their direction, but R109 needs to be set to its maximum resistance to start the test procedure.
Do I still measure between location 1 and 2 printed on the board for R109. Or do I need to determine which board has the flipped resistors and measure between 2 and 3 on the board to maximize the resistance to 500 ohms? I don't want to hit the board with voltage and have the pot inadvertently turned down to zero resistance.
I hope I've made my question clear.
Best to all,
John
Because adjustable resistors R11, R25 and R109 have side adjustment screws, you need to have them facing up. Since one board is flipped around, the Bourns pots on that board are flipped around to keep the adjustment screws facing up.
I suppose the midpoint is the midpoint regardless of their direction, but R109 needs to be set to its maximum resistance to start the test procedure.
Do I still measure between location 1 and 2 printed on the board for R109. Or do I need to determine which board has the flipped resistors and measure between 2 and 3 on the board to maximize the resistance to 500 ohms? I don't want to hit the board with voltage and have the pot inadvertently turned down to zero resistance.
I hope I've made my question clear.
Best to all,
John
The build guide its very clear about these points. Please take your time to review the build guide and post back if your still having trouble
Oversized is quite literally that. It means your wattage (VA, more accurately) available is larger than is what is required, as a result the rail voltages don't sag as much in heavy loads and you get a little more output power. (Kinda like stuffing a V8 in a V6 engine bay, ignore the gas milage penalty). Here, the penalty is quite literally physical size and cost.
There are no specific brands or models. Some common brands are Antek or Toroidy. Choose size and secondary windings accordingly.
Dual Monoblock means stuffing 2 separate transformers in the same chassis, each powering its own amp channel. The advantage is the amplifier channels do not share a common ground return. The disadvantage is space and cost. This can also be achieved by using more secondary windings from a more "typically" sized transformer to separate rectifier and bulk cap banks, but this is not truly dual mono.
Respectfully, if you are having trouble with understanding transformer sizing or understanding the above, you may want to read through the build guide available in the first post, completely, a couple times and assess if you are up to the task of building the wolverine. It is not a cheap or easy build.
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Honestly, if you have an issue with power supply sag, you are probably clipping anyway. You really need a larger amplifier under those conditions. The extra current doesn't buy you anything. I guess if the "normal" spec is marginal it will improve, so you just need to increase things a little - iff (if and only if) that is an actual problem.
Yeah I did have extremely in there before heavy load but removed it.. and the normal spec definitely isn’t marginal.
I don’t think the extra power (headroom) is going to be audible to anyone going from normal to oversized, heck you could even go undersized and probably not notice but let’s not open that box.
We just sometimes like to go over the top because it’s cool and we can and bigger is gooder (see 2000VA transformers and 150,000uF caps etc) 🤣
Stuart, I've read the build guide a couple of dozen times. I don't understand it. Build Guide Revision 43 (7-10-23) Section 16.2 Setup IV. says "Verify that R109 is set to its maximum resistance of ~500 Ohm as measured between pins 1 and 2." Does this mean measure between pins 1 and 2 of the pot even though it's upside down? Or does it mean measure between location 1 and 2 on the pcb? It seems to me the circuit on the pcb matters. Or am I completely off base and looking at the wrong section of the Build Guide.
I realize answering these questions must be frustrating..frankly I don't know how you do it. You seem to have infinite patience. I want you to know I appreciate it, and I could not build this amplifier without it.
John
Thanks RickRay. But didn't the orientation of the pot with reference to the pcb change? This would cause you to have to turn the adjustment screw in the opposite direction to increase resistance, wouldn't it? So to max out the resistance on the pot do you measure between pin 1 and 2 of the pot regardless of its orientation, or do you go to location 1 and 2 on the pcb and measure there?
I appreciate your interest in getting me to the point where I understand this.
John
@jminassi
I don't have the build guide but generally if you're trying to set the resistance of a potentiometer to max, turn it all the way to the right, measure on it's pins with ohm meter (polarity doesn't matter), turn all the way left, measure again and you'll know where the max is. Just check as they usually come with 3 pins, which one are pin 1 and 2. If you have BOM handy, you can post the model of the trimmer here so we can check the pin layout.
I don't have the build guide but generally if you're trying to set the resistance of a potentiometer to max, turn it all the way to the right, measure on it's pins with ohm meter (polarity doesn't matter), turn all the way left, measure again and you'll know where the max is. Just check as they usually come with 3 pins, which one are pin 1 and 2. If you have BOM handy, you can post the model of the trimmer here so we can check the pin layout.
Always measure between 1 and 2 labeled on the board, the board didn't change. You are right you will twist the screws different directions on the two boards.
The orientation of the board, or the Pot, doesn't change this fact.
You left out the important footnote in blue 😉
2 & 3 on the PCB are shorted together (or 3 might be a blank pad, I'd have to double check) as we are only interested in making a variable resistance across 1 & 2 i.e. using a potentiometer as a variable resistor.
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Yep, it has 3 pins. Those pin numbers are hard to read. Mouser P/N 652-3296X-1-501LF. The adjustment screw is side mounted. My pcb's are parallel to the heat sinks.
Thanks,
John
Thanks for the reply! It makes sense.
I am comfortable with this build, I just have a lot to learn and catch up with on how this design was established. I have built both the Amp Camp Amp and the Akitika amps with good success. I wish I could get access to the BOM and updated build guide.
Does anyone have any examples of Wolverine monoblocks that have been built? I am looking for inspiration and also ideas for the case.
Pin 1 is the furthest away from the screw and pin 2 is the middle one. Please measure it to the desired value (I guess 500 ohm). PCB orientation relative to the heat sink does not matter.
What does the manual say, do you measure it "in circuit" (trimmer already soldered to the board) or you first set the trimmer and then you solder it to the board?
Yes pins 2 and 3 are shorted on the pcb. But if one pcb is facing up and the other down, then pins 1 and 2 of the pot are not going to be in the same location on each board. This is the source of my confusion. It seems the circuit should rule. As long as the resistance measured on the pcb locations marked 1 and 2 is 50 ohms, you should be good. You will have to turn the adjustment screw in the reverse direction to adjust it. Correct?
You need to put the ohmmeter probes on pins 1 and 2, no matter of the orientation of the PCB, heat sinks or anything else. Same goes for screw turn direction, you need to turn it to 500ohm, not left or right.
The latest build guide and schematic is on the first post. BOM is reserved for PCB purchasers. (It is made available to you at payment so well before you receive boards).
See first post also - Wolverine build album. Stuart’s monoblock build album is absolute reference material.