Black Widow [Update] - Second round official, 100 amps total, single chassis

Oops! Guess I'll walkin' the plank soon.

 

So I have a BW1 in the house on loan from @lodexfa and @CEE TEE (Thanks guys!)

The first day sounded fine, then the next day picked up lots of transistor noise. I thought it was my source, my cables, etc.

I got curious and saw on the inside should be +/- 24 V rails. I checked, and only +/- 10 V. This made sense now why the power supply was so hot because regulated power supplies waste heat to bring the power down. So I checked the power supply, not the same board in the BW1 as BW2, but similar and two adjustment pots that changed the voltage. A quarter turn was all it took to get it from 10 V to 24 V. Touchy pot.

It would have made more sense to put in some kind of resistor to have less range in that pot, or to use wax or a dab of nail polish to keep that set adjustment screw in place, like I have seen on some many fixed bias pots.

The same pots are used in BW2 power supply and a similar design although slitly different, but if you have noise issues, check the DC voltage rails and keep them at +/- 24 volts.

Impressions later, but yes, killer amp. One of the best solid state headphone amps for sure.

 

I don't know kw what to tell you, it might have been a half turn, but not much. A slight eek and it jumps about 0.2 to 0.4 V. Not much friction on those adjustment pots.

It was hot because a 24V 50 VAC is gonna dump a lot of heat when regualted down to 10 V.

At normal operating voltage and on for 2 hours was just barely warm. Only dropped about 2 V in regulation after warm up. So I adjusted. I'll continue to check it over the next few days.

 

Update on this as I was told that some of the power supplies that were sold with the BW1 were only rated for +/- 18V rails. Hence why the pots were so touchy, it was running hot, and only at +/- 10V rails when it arrived. Apparently these boards were some Chinese shunt power supplies that you could get on eBay and never meant for +/- 24V.



Note: This was only for the BW1, not for the BW2 that had a upgraded power supply.

This particular power supply died, went poof, and let out the magic smoke (at least on the positive rail). So I will be building a new bipolar supply for this BW. Thankfully I can still use some of the parts (transformer, plug, switch, and connector).

 

UPDATE:

Finished building an AMB Sigma 22 and used the XLR connector, power switch, and Triad transformer from the original PSU.



Tracks the needed +/- 24V nearly perfectly. Sound is full and clear as should be. A definite improvement over the Chinese shunt power supply that came with the BW1.

As far as a comparison with the BW2 PSU, probably a real close call. I don't ha e one here to compare, but both are linear PSU's and likely not very different. It sounds just as big and dynamic.

I can see why some love the AMB σ11 single rail, and σ22 bi-polar PSU's. Although the board is quite big.

 

Hoping someone can help me with a Black Widow 2. I recently got one on loan, and one of the LEDs inside (D15) was dead. Tried replacing it, no dice. I ended up replacing Q7 and Q11 upstream, then the replacement LED worked. I couldn't find LEDs that had the exact same forward voltage, so I ended up replacing all four so they would match (only 0.1V difference).

Does replacing the transistors and LEDs necessitate adjusting the trimpots? I have no idea what any of them do but want to make sure things are kosher before hooking headphones up to it again. Seemingly ok with my KSC75 testers, but you never know.

 

Turns out things were not all ok. That same channel had 400mV of DC offset and other issues. Turns out D1 and D2 were blown. Replaced those and now everything is seemingly good to go! However, my dumb self messed with all the trimpots while I had it scoped to see if that could fix anything, and now I'm not sure how to set any of them? Anyone have any guidance on that?

 

Best is to check with someone at Eddie Current. I inquired about the same thing and I did not get a response. Of course I was emailing about other things as well. To me, most of these amps sold through this community and he should be able to answer a few questions about them and still protect the intellectual property of the design.

The only other person that might know anything is @purr1n, since he helped put together the sale for the BW2 amps and possibly a hand in assembly.

 

I asked purr1n and Craig. Craig responded that they have lost the schematics for the BW2, but told me to measure the DC across the emitter resistor and adjust to 35mV. Unfortunately, the lowest I can go is 80mV. The channel I didn’t touch measures about 470mV.

EDIT: VR3 should be set so that you measure approximately 350mV across R25. VR1 sets the DC offset of the output.

Craig told me that VR1 and VR2 don’t matter and that I could turn them both fully clockwise. Doing this to VR1 caused the DC offset to be -400mV! So VR1 does matter lol. I still haven’t determined what VR2 is doing.

 

Thanks for this info!

I have a BW1 and the boards are very similar. I guess in messing with mine, it is now fried. All I get is distorted audio. RIP

 

Currently experiencing no right channel with my Black Widow 2 as of today. The same RCAs into my Jotunheim, same headphones, works fine. I left it unplugged for a few hours but still no right channel. I'm willing to open it up if anyone knows what might be wrong. Gotta be something I can do

 

Uh oh. Could just be an internal connection inside from the input connectors to the volume pot, the volume pot to the board, or from the outputs to the headphone jack.

 

Does anyone have any idea what VR2 does? I’ve measured and scoped and everything. Cannot figure out what it does or how to set.

 

Happy to hear my BW2 is perfectly fine. Just left it alone for a few days and the right channel fixed itself. Happened one other time in recent memory, is there a failsafe I might be triggering? Or might I have a loose connection internally?

Anyway, this thing sounds damn good, incredibly clean and nuanced. BW2 + gungnir MB ended my search for "good sound" over 2 years ago. I binge as many albums as I want and never get tired.

 

I agree. When I had a BA the PS meter pegged to the right. After carefully inspecting the PS board I found the solder around a transistor leg had cracked all the way around no longer making contact. A reflow of it and several other 'suspects' and all was well.

 

Same channel cut out today so I finally opened it up. The solder around the right input jack had lost contact. I carefully prodded it with the power on and soon the right channel returned—problem identified, thanks for all the help! I'll ask a friend to resolder it. Easy solution

 

You might want to check all the solder joints while you're at it. Could prevent headaches later.

 

The Black Widow has slowly become my favorite headphone amp ever, and I've owned many.

No it's not as resolving as my old 445 (but very close), no it doesn't beguile in the mids like my old ZDSE, but it actually combines elements of those two amps in a SS package. It has the vivid tonal color, pizzazz and grand spectacle-ness of the 445 (with the warmer tubes I had in it), and it has the warm, seductive, enchanting and haunting emotional involvement I felt with the Zana.

On top of that it imbues qualities of solid state.... like extreme clarity, speed, razor sharp precision, unadulterated bass slam and timbral honesty that I feel are welcome additions to the Eddie Current house sound. The Black Widow is like the amp I never knew I wanted. It's also extremely transparent and differences in DACs and playback sources are not at all subtle, allowing me to tweak until I get to that perfect sweet spot.

What I love about Eddie Current is that every amp Craig made was meant to be somebody's endgame. He didn't make mid-fi amps, and you can feel the love, attention, care, energy and devotion he put into every one of his products. I always figured my endgame would be a tube amp... welp... life sometimes catches you off guard and shows you that what you want isn't always what you need!

And no tube nervosa!