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The Wolverine 5th Group buy

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#41
AdrianLevi said:
I found a store with 2SA1494, their website lists 1000 in stock. Are these likely to be fake/after markets at this stage?
If these aren't wise to base the build on due to obsolesence, what are other people planning to base their build on?
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High chance of being fakes with many of the MT200's. Unless maybe buy from a brick and mortar store in Japan that can show you some parts tracing.
FWIW Those transistors aren't on the BOM list for the amp. (Thats not to say they wont work, they just aren't tested or proven)

The biggest, baddest output that is still readily available is the MJL4281/4302 combo.
 
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#42
Holy schnitzel! Back to the drawing board.

500VA 50V AC -> 71V DC rails -> 200W@8ohm for one channel -> Need EF3-4 boards and bigger chassis (e.g. Deluxe 5U or 4U 400mm depth) as explained above
500VA 45V AC -> 64V DC rails -> 200W@8ohm for one channel -> Need EF3-3 boards and smaller chassis (e.g. Deluxe 4U)

Hope I got it right this time LOL!
 
#43
Yup looks good. Theres also nothing wrong with putting the EF3-3 3pair output boards in a 400 Deep chassis, if you want the extra room.

You need to think about auxiliary boards you might want to use - things like soft starts, speaker protections, housekeeping boards, auxiliary supplies (small transformer, mini SMPS or custom auxiliary winding on your main transformer...) for all the aforementioned... Theres a bit to think about, don't rush it.

64V rails is probably the sweet spot. Allows for the smaller chassis, and use of 80VDC capacitors instead of the more expensive 100VDC capacitors required for 71V rails. 70-71V rails really starts pushing the costs up.

71V rails with a EF3-4 board should really be in a 5U chassis IMO.
 
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#45
Heaps more info in the build thread.

https://www.diyaudio.com/community/threads/diy-class-a-b-amp-the-wolverine-build-thread.385920/

My suggestion if you want to start researching is do a google search with the "site:" parameter followed by the thread URL and then a space and then your search terms.

Here's an example of searching the build thread for "4U chassis"

1742341914295.png
 
#46
saabracer23 said:
Count me in for four if the EF3-4 boards and associated parts. Just in case I can’t open and fill out the sheet, I remember kind of having trouble with that last time.

4 V5 EF3-4 boards

I would like all the associated heat sinks for building these four channels. I’m not entirely sure which ones to get, I’m guessing the one that covers all of the heat sinks I would need.

I would be interested in the bridge rectifiers, the speaker protection, the T ground, and ground lift boards. I guess I would like to hear opinions on what people think the benefits are, would the speaker protection degrade the sound or increased distortion at all? I’m not super familiar as you can see.

Also, I have Onsemi KSA1381E and 2SC3503E which from what I understand are Sanyo, yet the package says “ON”. I’m guessing it would be okay to pair these.


I purchased four boards in between some group buys, are these the fourth group buy? Or second?
View attachment 1435205

Anyways, I am building these out to be on the 71 V rails, I noticed that voltage isn’t mentioned with the fifth group by, any reason?

Thanks!
Dan
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Sorry Dan, missed your Q's.

Speaker protection won't degrade the sound. Unless you use a relay style protection, and the relay terminals have corroded badly with age. Most protection boards now are moving to a MOSFET style.

Those are second group buy boards you show.

Voltages are still selectable by builder, 50 to 70VDC rails.
 
#47
It has been found that mosfets do indeed degrade sound quality. Not much, but a good relay is better. I have watched this carefully.

Relays are a maintenance item. If you don't open the contacts with current running, they don't pit. They might if you have signal on them when it closes due to contact bounce. Using a Mosfet appeals to people who want maintenance free, but as always that come at a cost.

With an amplifier this good, I wouldn't throw problems in it's path. At least a Mosfet isn't as bad as a relay with damaged contacts (but then it should have been replaced anyway).
 
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#52
Some of us did 🤣. In fairness, they are ultra-low noise, very nice transformers. Just beware their SKUs don't include small auxiliary windings, and you need to email them for custom order if that's what you want.

dovla83 said:
500VA 45 0 45
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Make sure you order a "2x45" and not a "45-0-45" if you plan to use the dual rectifier type PSU. If using conventional single rectifier style, 45-0-45 will be ok.

1742347546640.png
 
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#53
Some of us did 🤣. In fairness, they are ultra-low noise, very nice transformers. Just beware their SKUs don't include small auxiliary windings, and you need to email them for custom order if that's what you want.
Click to expand...

Well I already have some correspondence going as they don't do 120V primaries by default and waiting for the shipping price to Canada so yeah...call me crazy...

Make sure you order a "2x45" and not a "45-0-45" if you plan to use the dual rectifier type PSU. If using conventional single rectifier style, 45-0-45 will be ok.
Click to expand...

That's a good tip, thanks! I did went with the dual rectifiers per channel (W12 CRCRC Dual).

Regarding the small secondaries, do I even need them? Amp boards, rectifiers, soft start and speaker protection, I guess non of these need it?
 
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