Audion Black Shadow

Kingrex

Kingrex

Active member
Joined
Dec 17, 2017
Messages
1,187
Location
Seattle Washington USA
I bought some new used amps. My goodness its nice to finally have quiet amps. It has taken some tunning, but I finally have this set running and at its best, put my head to the woofers or horn and its black. Maybe a tiny hiss from the horn. At its worst there ia a faint hum out to about 2 feet. Further out I can't hear it. Hugh plus for me. For years I was chasing noise thinking it was my utility. It was just a poorly built set of amps.

The Black Shadow is a 845 SET amp. Its different than the standard KT PP type amps I'm use too. I have a speaker that are called efficient at 96db. But, its 2x15" woofers and a horn per speaker. Because of this I opted for a 22 watt SET. Not one of rhe 2.5 to 4.5 watt version. I'm glad I did.

This amp is pretty darn picky. If you have deficiency in your system, this amp may call it out in ways you don't like. But with any new add, you have to tune.
First for me was pre tubes. Dam if it doesn't sing with a Telwfunken E88cc. It works with other $40 tubes, but it comes alive with a nice pair or $300 Tele.
Second, I had to mess with footers. They made a difference.
Third, they are used and I had to engage in some TLC. One thing I noted was one of the power tubes seemed to float and the other was locked down. I ended up putting fresh rubber washers under the ceramic base. It made a large impact for the better.

At this point they were playing dam fine with my vinyl, but the digital was fatigued. Why why why. After a couple days and texting with the guy who sold them to me it clicked. I had put a set of Ching Chang power cables to my dac and server a few months back. Hmmmmm. I pulled the C.C. off my digital, put them to my preamp and took the preamp power cords (Found Music) and put them to the digital. TADAAAAA. That was it. Now both the vinyl and digital sing.

At first I was pretty concerned over this purchase. Now that I have tuned it into my setup I'm very happy. I can see these amps staying with me for quite a few years.

I have a couple other tuning options to address.
1. I have to lift the ground to make these work. A HumX also works. But my power supply is bolted together at the power cord and branch circuit. So I am having a custom set of back to back diode installed in my amps on the ground. That will block micro volts and act like a lifted ground, but pass dangerous voltage on the ground and trip a circuit breaker
2. These amps have a pretty cheap Alps pot on the input. I have found the sweet spot and measures the resistance at that level. I'm going to replace the pot with a Naked Vishay foil resistor.
3. I may change some caps in the signal chain. But the amps are pretty darn good as is. I'm not sure a cap change will improve it. I want to get the pot out and live with it a while before I determine if It needs more of anything.

Rex
 
So happy you’ve found a great solution Rex. Congratulations.
 
Congrats! Especially during social distancing new audio toys are always a welcome distraction.


Sent from my iPad using Tapatalk
 
Thanks all. I'm pretty happy. I do have another issue to try and resolve. I sent my preamp to be updated. When I did, I simply took the rca from my preamp to my amps and put them into the back of my DAC. Being that the amps have a volume on the front, its a nice temp volume control. In doing so I was presented with the most inky black background I ever heard from my stereo. That is how I noted the performance of these amps above. When my preamp is in, the hum is a bit louder and at its worst can be heard at my chair very faintly. At its best I can not hear it at the chair and at the speaker is very faint. So, I have some sort of reaction or ground loop between my preamp and amp. Maybe its just my preamp boosing noise and handing it to my amp to be boosted again. I don't know yet. I have some testing to do. But the amp via my DAC is so very quiet. They are a nice find on the used market. I will get it figured out.

FWIW, I do miss some of what KT PP type amps present. If I had not heard a nice SET, I would also not know what KT PP type amps themselves don't do. Nothing is perfect. But for now, these are fine amps I will use for quite some time.
 
Thanks all. I'm pretty happy. I do have another issue to try and resolve. I sent my preamp to be updated. When I did, I simply took the rca from my preamp to my amps and put them into the back of my DAC. Being that the amps have a volume on the front, its a nice temp volume control. In doing so I was presented with the most inky black background I ever heard from my stereo. That is how I noted the performance of these amps above. When my preamp is in, the hum is a bit louder and at its worst can be heard at my chair very faintly. At its best I can not hear it at the chair and at the speaker is very faint. So, I have some sort of reaction or ground loop between my preamp and amp. Maybe its just my preamp boosing noise and handing it to my amp to be boosted again. I don't know yet. I have some testing to do. But the amp via my DAC is so very quiet. They are a nice find on the used market. I will get it figured out.

FWIW, I do miss some of what KT PP type amps present. If I had not heard a nice SET, I would also not know what KT PP type amps themselves don't do. Nothing is perfect. But for now, these are fine amps I will use for quite some time.
 
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