DIY Class A/B Amp The "Wolverine" build thread

I use one i bought years ago.
I am actually looking into heated ones now. Obviously I am not going for hakko its just too expensive but some other alternatives are possible. Either heated suction, recoil ones or with continuous suction via air pump. I'll pause this troubleshooting until I get something better
I bought a Hakko FR-301 about 2 years ago and it has been a awesome. I had issues with applying heat and then quickly putting the sucker in position. This thing works wonders. Once in while I'll need to add solder before removing it, but very efficient. Well worth the expense.
 
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Schematic and PCB layout are critical and make a huge difference. Some part types matter a lot also. Transistor matching in some locations also matter a great deal.

You can have the same schematic with two different PCB layouts and they may perform worlds apart.
 
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Is quality of the pcb impacting the distortion in any way? i am curious as to what's the crucial part that makes the wolverine so great. or is it just the schematics and biasing.
I think all....but for me the most important about distortion it is the topology schematic....OS
So the Wolverine its a Great Amp for sure ....its a Neutral amp not a Musical amp....
 
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I completed my Wolverines this weekend. I am pretty happy with how they turned out. Over the years, I've incorporated a lot of my design learnings into the amp chassis. The initial design started in January. A lot of time was spent on waiting for parts from suppliers local and around the globe, but I intentionally took my time on this one.

There are two monoblocks. Power is from MicroAudio SMPSs; it's my first SMPS build. Each Monoblock also has an off-the-shelf smart controller rated at 4000W that controls remote power on/off and high/low voltage and current shut-off. This is tied to my home automation, so my audio setup can be started and shut off in a specific sequence.

The chassis is made of 2mm steel and weighs a ton. Considering the look I was going for, I had to go with this.

The enclosure separates the power supply and amplifier sections. It is made of 6mm of steel and has a considerable air gap. The power supply and associated wiring are almost completely confined to one side, and the ventilation on both sides is exceptional.

This was during testing and initial wiring clean-up. The vertical mounting offers excellent airflow. The heating and PSU are mounted on individual brackets. The PSU has enough space to accommodate a toroid, but I have to say that these MicroAudio SMPSs are sounding great.

I designed the enclosure for access, so at any point, it is pretty "easy" (a bit backbreaking with 2mm steel!) to take out an individual bracket to work on.
View attachment 1344024

I've installed some horizontal supports. These assist with the rigidity of the enclosure and, on the amplifier side, are supposed to create airflow channels.

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The lid was a design challenge; metal bending has limitations, so I had to design it in two parts. I also had to create a special clamping system to keep the spacing between the two parts equidistant so that they don't scrape the chassis when you put them on.
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These are the final amps in place.

Monoblock A
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Monoblock B
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Sound is subjective, but I have to say that these are pretty incredible.

I just wanted to thank the design team and everyone who offered advice. It's been a pretty tough year, and I don't think anyone talks about how projects like this can give you something immersive and ultimately positive to focus on—special thanks to Stuart for some sideline advice and encouragement.
Very very nice 😎
 
Ok, ready for more dumb questions? I am so close to turning my Mouser project into a shopping cart, but....now that I have all the part numbers and quantities in there I started to think about matching transistors for performance. At Section 14 of the Build Guide (dated May 22, 2024 2nd Group Buy, but I have the 3rd Group Buy boards which I believe are identical) it says to match Q1 and Q2, and Q3 and Q4. But shouldn't Q5 and Q6 also be matched as all three pairs are bonded for thermal tracking?

With help from mainframe99 I finally decided on Onsemi NJW3201/NJW1302 output transistors. Should these be matched too? I don't see anything in the Build Guide on this.

I'll be using a Peak Atlas DCA Pro 75 to do the matching. How many of each type of transistor would you recommend I buy in order to get the Hfe/Vbe matches? I can't pull the trigger on my order until I know.

Do any other transistors need to be matched?

Separate question: I now realize that because I am mounting my EF3-4 boards parallel to the heatsinks, I can completely eliminate the 3mm thick heatsink with Q107 and Q108 mounted on it. I'll mount them on the main heatsink under the board and put Q103 right between them. I have the diyaudio 5U chassis with the standard UMS heatsinks. I haven't checked yet, but I am surmising that I may have to drill a few M3 holes to accommodate these transistors. Am I thinking about this correctly?

Many thanks,

John

PS: Did I mention that I get shaky when I'm not soldering😀.
 
But shouldn't Q5 and Q6 also be matched as all three pairs are bonded for thermal tracking?
See here on matching : Post 3476

Should these be matched too? I don't see anything in the Build Guide on this.
Hope you didn't buy loads of these. Unlike sankens and toshibas, these will be crazy close 1-2% same type and about 5% between types, there is no need to worry.

I'll be using a Peak Atlas DCA Pro 75 to do the matching
This is good. Any builder can do wolverine with just a multimeter.

How many of each type of transistor would you recommend I buy
for Q1 2 3 4 5 6 I would suggest 50 min each would likely get you all the matches you need.
Do any other transistors need to be matched
As linked above. Up to you. Only Q1 2 3 4 critical. I've done amps matching only these, and the amps amazing.

I haven't checked yet, but I am surmising that I may have to drill a few M3 holes to accommodate these transistors. Am I thinking about this correctly
Yes, as I mentioned previously, you will need to drill and tap Q103, 107 and 108 holes 🙂
 
To match transistors, they need to be at exactly the same temperature. I mean exactly.

I gave the forum members a jig design to match transistors ages ago, several boards have been designed for it so far. "Testers" never get the matches close. The jig places two transistors in a diff pair configuration, you mount them together, they are run on a current source for tail current. You simply look for a null between the collectors (0.1% resistors). It makes a difference.

Touch a transistor or breathe on it, and your peak (or any meter type) matcher will not give you the same results, plus the jig is very sensitive. The only way you can match them closely is if they are run a the same time, same current and thermally isolated together. You put foam over the pair, hen a box over that to block air currents. Yup, transistors are that temperature sensitive.
 
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In certain locations, it is critical. It reduces distortion and DC drift.

You can lower distortion by matching complimentary drivers and other parts. Output stages with matched transistors exhibit lower distortion as well. If you have other problems you won't see improvement. If the circuit and build are performing well enough, you will. That assumes you have equipment good enough to measure down to those levels.

The diff pair is the error comparator. It can't do that well if it isn't very closely matched. Errors in following stages need to be corrected via feedback. The less correction needed, the lower the distortion and the better it sounds. It's terribly logical.
 
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Then temperature was 28-29 degree, nonmuch difference


Yes, bias at the start it goes up to 48-50mV then as the amp is getting hotter bias goes back to 43-44mV and then is stable.
I hope you see the same values 48-50 again in mv and them 44 mv steady and the winter. I probably have a problem with my amplifier. And I say this because it was regulated in the winter at 44 mv and now in the summer when I put him back on the bench I counted the maximum at 30mv bias with the same temp on heatsinks at 40C. at the two channels
...
 
Hi Guy's,

While I agree that transistor matching is important and worthwhile, I’d like to share a different perspective based on our experience during the prototype phase of the Wolverine development. At that time, we conducted distortion testing without performing any transistor matching at allg. I just looked back at the measurements and we were able to achieve a distortion level of 0.000285% at 1Khz with a bandwidth of 20kHz and 96kHz at 80W with an 8-ohm load.

So, my point is that while transistor matching is beneficial, it's not something to stress over if you can't achieve perfect matching.

Additionally, in simulation, it appears that matching transistors Q3-Q4 is the most critical, followed by Q1-Q2.
 
Hi Stuart,
Yes, if the design has intrinsic low distortion in the output and Vas stages, it will have low distortion for sure. As you also noted, matching closely can matter. Maybe it also depends on how much performance is important to the equipment. That low distortion makes no sense in a disco or rock concert. It may matter in a very high quality reproduction system. If your main speakers are Bose or Cerwin Vega then who cares for example? I'm sure I just offended some folks.