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

[stuartmp]

Where can I get the latest version of the Wolverine schematic, including the .asc file for ltspice?

I looked for about 100 pages here on the forum and couldn't find it.

Hi Carlos, we are not sharing the .asc file at this stage. You maybe able to modify the one that OmeEd mentions using our latest schematic. The .asc version that ostripper posted was not the final version.

 

[stuartmp]

What’s next, a holiday?

Yes, we are all taking a break. Thank you for supporting the fellow members in this thread. I've seen quite a few of your helpful posts. 🙏

 

[kolakidd]

I am cutting the the VAS, Pre-Driver, and Driver heatsinks.
Is there any point in making them taller (from 30mm high to 50mm high)? I have the space to acccomodate a taller heatsink

 

[fireanimal]

I would not make the un-pinned heatsinks bigger. Too much leverage on the leads.

 

[richbandit]

Hi Guys,

Excuse the quick basic query - what are the implications of not grounding the on-board heatsinks, on both IPS and EF3-x? Bad, or fairly insignificant? Is it absolutely necessary?

 

[OmeEd]

Usually the heat sinks are already grounded by the mounting bolts to the metal chassis, in that case, additional grounding is undesirable because it creates a ground loop. I put a ground wire on the heat sinks only if they are floating and/or touch sensitive.

 

[fireanimal]

I have tested both ways and it makes no difference in this case, but depending on the wire used, it can improve stability.

 

[richbandit]

Thanks to both for responding so promptly!

@OmeEd - Are you referring to the main heatsinks for the output transistors, part of the enclosure ....... ?

I don't mean those, I was referring to the CCS2 &VAS, pre-drivers and drivers aluminium heatsinks fitted on the IPS and EF3-x board directly .....

@fireanimal - if your response relates to these 'on board' aluminium heatsinks then that answers my query, many thanks - could you kindly confirm that is what you meant?

 

[OmeEd]

Yes my answer is related to the main heat sinks, I realize now I misread your question, sorry about that.

 

[fireanimal]

Correct we are talking about the same ones, the CCS/VAS heatsink and the Predriver heatsink.

 

[richbandit]

Many thanks both, cleared up nicely!

 

[mainframe99]

Slightly OT but I been thinking, If one was to only swap output transistors completely from one set to another, would the bias adjustment need to be remade? Why would this be? I'm just thinking if my (hard to find) outputs ever poofed, I could have a spare set of something more common in storage. And that got me thinking the above. Obviously, its not hard to recorrect the bias, but why would it differ, and by how much?

 

[hcpower]

From a noob who just did a output swap in an old amplifier: different Vibe is my first thought why BIAS might need adjustment

 

[EdGr]

Is in the Ebers-Moll equation will differ. Is can be estimated from the graph of Ic versus Vbe.
Ed

 

[OmeEd]

An emitter follower is a voltage follower, not a current follower. Ve = Vb + Vbe. However Ic = Ib * beta. Since beta difference from device to device and also depends on other properties like collector current and temperature.

 

[EdGr]

The relevant variable is Is, not Hfe. The output transistors are driven by a low-impedance voltage source.
Ed

 

[OmeEd]

Of course, but quiescent current is a current, not?

 

[EdGr]

Ie = Is * exp (Vbe/Vt)

Yes. The bias adjustment controls Vbe which in turn controls Ie.
Ed

 

[stuartmp]

If one was to only swap output transistors completely from one set to another, would the bias adjustment need to be remade?

For safety I would set R109 to maximum resistance and then power up each amplifier module on the bench on a regulated supply as described in the build guide and using a lower rated fuse etc. Then adjust R109 to verify the output bias is working correctly. Then set R109 back to maximum. Once everything is verified reassemble each module back in your chassis and then power up and adjust your output bias and dc offset as described in the build guide. I'd also double check the ltp ccs just to be concerned.

 

[stuartmp]

Yes. The bias adjustment controls Vbe which in turn controls Ie.
Ed

The thermal resistance and HFE may also be different so I believe it best to reset and start again as I described above.