Forums - CSP 2+ Up in Smoke?

Tony

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CSP 2+ Up in Smoke?
01/25/23 at 14:55:24

About 18 months ago, I bought a CSP 2+ preamp from a Decware member, and it has worked as expected until yesterday. I powered up the amp and preamp, and shortly after, a loud hum came out of the speakers. Not the type of hum one could only hear if your ear were so many inches from the speaker; this hum/roar sounded like something out of the exorcist movie. Quick, I shut everything down.

The preamp's transformer was hot, and I could smell something burned. Luckily, nothing else in the system was affected. After pulling out the preamp, everything else played for a few hours without a problem. Later, I inserted an older ZStage in place of the preamp, and the sound quality was good.

The CSP 2+ needs to go back to Decware for assessment and repair. I quickly searched the Forum for similar reports or discussions and found none. When the preamp cooled, I opened it up and saw nothing suspicious. I saw nothing burned or charred due to the smoke smell.

I wanted to post this event and ask if anyone can opine on what the heck happened. No unusual precipitating event. No gradual decline in performance, just all of a sudden this problem. Tubes in the preamp appear to be OK, with no discolorations or markings.

Thanks in advance, Tony

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Lon Seasoned Member "Love without guts is worthless!" Philip K. Dick Posts: 25786	Re: CSP 2+ Up in Smoke? Reply #1 - 01/25/23 at 15:19:48 Tony, I suspect that perhaps the rectifier socket has failed. That mirrors a former incident in my experience with the Taboo. Sending it back is likely the best thing to do.
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Tony Seasoned Member "Life without ..music is inconceivable" A.Einsteln Posts: 746	Re: CSP 2+ Up in Smoke? Reply #2 - 01/25/23 at 15:39:13 Lon, That could be. I had forgotten that Steve coached me to tighten the rectifier socket using a dental pick on the preamp a few weeks ago. A simple procedure that seemed to go well, but perhaps I weakened something else in the process. Any idea of what accounts for the burning smell? Might I have fried the rectifier tube?
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Paul2

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Re: CSP 2+ Up in Smoke?
Reply #3 - 01/25/23 at 15:39:20

Hey Tony, Strange day for CSP2+ preamps.

This morning at 2AM I turned everything on as I normally do. NO SOUND !
CSP was cold !

Shut everything down and pulled the new Decware 5U4G and replaced it with a Psvane 274B. Nuttin'

Shut dow again and put the Decware rectifier back in. Everything returned to normal.

Have been playing music for about six hours now and it's perfect. Hopefully, tomorrow everything will be fine.

I just find it strange that you also had a problem with your CSP.

Good luck with getting your problem repaired.

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JBzen Seasoned Member Posts: 1529	Re: CSP 2+ Up in Smoke? Reply #4 - 01/25/23 at 15:42:10 Check to make sure the fuse has not been changed or eliminated. John
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Lon Seasoned Member "Love without guts is worthless!" Philip K. Dick Posts: 25786	Re: CSP 2+ Up in Smoke? Reply #5 - 01/25/23 at 15:43:53 I would wager that the rectifier has also failed. I change rectifiers so often (love to experience and analyze the profound effect they make on an amp) that I know that is why mine likely failed.
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Tony Seasoned Member "Life without ..music is inconceivable" A.Einsteln Posts: 746	Re: CSP 2+ Up in Smoke? Reply #6 - 01/25/23 at 16:03:39 If I understand correctly, check the fuse, try another rectifier tube, and test it out. My hesitation is the burning smell. It would be great if a simple fix were at hand as I thought back to Decware was the only hope.
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qaztar

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Posts: 36

Re: CSP 2+ Up in Smoke?
Reply #7 - 01/27/23 at 17:14:57

I've had a couple blown rectifier fuses on my CSP3. The first time it charred the fuse holder and circuit board. If the CSP2+ also has the fuse holder circuit board that might be what you're smelling-- the smell of FR4 or equivalent. I hadn't seen the dental pic and tube socket fix, but I do know one of my rectifier socket pins isn't the same as the others. Thanks for mentioning.

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Tony

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Re: CSP 2+ Up in Smoke?
Reply #8 - 01/27/23 at 20:05:21

Thanks, everyone, for your ideas.

I met with Steve yesterday, and he hunched that it could have been an anomaly. A flash that burned off something inside the rectifier tube. Like Lon, he suspected that tube was the source of the problem. However, the preamp blew a fuse when I tried to turn it on again with different tubes throughout. Back it goes to Decware for assessment and fixing.

The original rectifier tube seems OK, as I played it for a few hours in my SE84UFO without any problems.

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Tony

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Re: CSP 2+ Up in Smoke?
Reply #9 - 01/30/23 at 16:36:40

I am following up briefly with some current events in this thread I started last week.

Above, Lon had suspected that the rectifier tube in my CSP 2+ may have been at fault, producing those bizarre sounds from the speaker. However, since that same tube seemed to function well with the SE84UFO, I figured that suggested no tube problem. I'll come back to that.

I have sent my CSP 2+, which stopped working entirely after overheating, back to Decware for assessment; it should arrive tomorrow.

As luck would have it, yesterday, I happened upon another 10-year-old CSP 2+ preamp in pristine condition at an estate sale in SF. The previous owner had been a Decware enthusiast with two or three other Decware amps. I could not pass up this CSP 2+. I figured the audio gods had placed it in my path. I bought it, played it with the SE84UFO last night, and it sounded terrific.

Since everything was working so well, I dropped the rectifier tube Lon initially suspected was problematic into this newly acquired CSP 2+. And, once again, from the speaker, I heard that same roar I had heard before. I quickly shut down the preamp, replaced the rectifier tube, and all worked well again.

So, the rectifier tube that worked with the amp does not want to work in the preamp. That does not make sense. What is happening with that rectifier tube? Any ideas? Thanks.

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CAJames

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Re: CSP 2+ Up in Smoke?
Reply #10 - 01/30/23 at 16:58:09

Quote:

Posted by: Tony Posted on: Today at 08:36:40

...So, the rectifier tube that worked with the amp does not want to work in the preamp. That does not make sense. What is happening with that rectifier tube? Any ideas? Thanks.

Different amps have different current and voltage requirements so a tube working in one is no guarantee that it will work in another. I suspect if you kept the rectifier in the UFO it would fail sooner rather than later. But a tube not working in one ought to be thrown out IMO.

FWIW when a rectifier and/or fuse blows a good plan is to remove the rectifier and replace the fuse and start up the amp to confirm or deny the other tubes light up. If the don't then you've got a big problem. If they do then at least the low voltage filament circuit is working and you can add a new rectifier and proceed with playing music.

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Tony

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Re: CSP 2+ Up in Smoke?
Reply #11 - 01/30/23 at 18:18:51

If I understand, there would be no danger of starting the amp/preamp without a rectifier tube. If the other tubes light up, that reveals proper functioning.

I was concerned that turning on the amp/preamp without a rectifier might harm something else. It sounds like that is not the case. It tests the low voltage filament circuit.

I will take your advice and dispose of the rectifier tube even though it worked with the amp. Too bad, it was one of my more expensive rectifiers.

Thanks.

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CAJames

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Re: CSP 2+ Up in Smoke?
Reply #12 - 01/30/23 at 18:40:09

Quote:

Posted by: Tony Posted on: Today at 10:18:51

I was concerned that turning on the amp/preamp without a rectifier might harm something else. It sounds like that is not the case. It tests the low voltage filament circuit.

Correct. The rectifier is in the high voltage, aka B+, circuit that connects to the tube plates.

Quote:

I will take your advice and dispose of the rectifier tube even though it worked with the amp. Too bad, it was one of my more expensive rectifiers.

I hear you, but we've all been there, or will be if we have tube amps long enough. For me the only tube I've lost in my UFOs is a high dollar Mullard GZ34 fat-base smooth-plate that should have lasted my lifetime

. This is why solid state is popular.

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Sumiko Pearwood -> Mapleknoll Athena -> Luxman SUT -> Mapletree Phono 3E
STR-1002 -> Woo WA22 -> 2x UFO25s, balanced monos
Omega SAM , Hifiman Arya, Audeze LCD-XC

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