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Lots of problems with my CSP2+ (Read 6141 times)
Mad Dude
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Lots of problems with my CSP2+
06/04/12 at 19:17:56
 
Hello everyone,

I'm the owner of a CSP2+ since about two months. First, let me say that it sounds terriffic - I primarily use it as a headphone amp, and I have yet to hear one that sounds more life-like than the CSP2+. Unfortunately, I have several issues that bother me... let me start from the beginning:

- When I received the amp, I immediately noticed some background humming. I do realise that a tube amp will never have a perfectly silent background, but with the CSP2+ it was clearly audible even when listening to music (in more quiet passages, anyway). I would call it baely acceptable, and was about to return the amp - but then decied against it, and hoped that the humming would get better with different tubes.

Since then, I have purchased several new sets of tubes for the CSP2+. While the humming issue actually did get better with some of them, there were additional problems...:

- I first tried some NOS Sylvania 6922. I tried every tube separately - keeping the stock 6N1P in the two other positions - and observed with a shock that the tube started arcing after about 10-20 seconds. After removing the faulty tube, I tried the amp with the stock tubes, and luckily everything sounded alright. I then tried the other Sylvanias, first in front, then in the rear position - both started arcing like the first one.

- Next, I tried some Amperex Bugle Boy 6922's. These did not arc (phew!), but presented other problems. I had two pairs: the first was extremely microphonic, the second pair exhibited a weird sort of hissing noise, which from time to time would grow louder and then turn into a faint crackling noise. Note that this appeared when I tried the tube in the front position.

- I then tried some new production ECC88's. This time, no crackling or hissing (humming was still there) - but when listening to something, there was an enormous amount of distortion, even on low volumes. This was consistent with all three tubes. Poor quality, I guess...

- Finally, I tried a new production EH 6922 in the front position, and two Amperex 6922's in the rear position. With this combination I've had the best overall result, and that's what I'm using since about three or four weeks. Only one issue was persistent, an occasional, irregular, faint crackling in one channel. This didn't bother me too much, but it was audible if it occured just in the pause between two tracks.

- Today, with the tube combination mentioned above, a new issue appeared out of nowhere: a distinctive hissing in the left channel, which turned eventually into a crackling noise - the same that I had discovered when I tried one Amperex tube in the front position. I was somewhat ennerved and decided just to go back to the stock 6N1P tubes, with which I did not have any problems before. And guess wha - the exact same problem occured with these tubes as well!

I tried most of the combinations listed above with three different rectifiers: The stock one, an RCA 5Y3GT, and a GE 6087 (which is, I think, mostly identical with the 5Y3GT). I did not notice any difference between them, so I think the rectifier is fine.

... well, I'm at my wits end. Does anybody have an idea what is wrong with my amp? Could it be that the arcing Sylvania tubes have damaged the amp, so that my problems are now persistent with all tubes? And further, just how much background humming is normal for this amp?
I'm trying to make sure that the problem lies with the amp, and not the tubes - I'm in Europe, so shipping the amp back to the US for a check-up would be very expensive, especially if it should turn out that nothing is wrong with the amp itself.

Really looking forward to your replies. Thanks! Smiley

lastly, I apologise for any grammatical errors - as you surely have noticed, English is not my primary language Wink
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Lon
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Re: Lots of problems with my CSP2+
Reply #1 - 06/04/12 at 19:36:47
 
Mad Dude, your English is excellent.

I've always had some hum in my system with the CSP2 in place. I don't use headphones and it's not audible at my listening position, so I would say it is not unusual to have some hum.

To be honest, those sounds are what I've heard from tubes before, not amps. It would seem unlikely that with those different tube sets that you'd have all noisey tubes however.

I know that the best person to answer your questions is Steve himself. I would recommend sending an email to Sarah@decware.com asking her to get Steve to give you advice through email. I suggest Sarah as I've had really good luck getting emails through to her.
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Rivieraranch
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Re: Lots of problems with my CSP2+
Reply #2 - 06/05/12 at 03:52:58
 
Don't give up on the unit. I have had arcing, too and I posted about it. Put the strongest tubes in the driver positions because that circuit is most demanding on the tubes. I find that the 6N1P tubes do not arc in the driver positions because the tubes are rugged. The input position is an easier circuit on the tube. You can use any tube there and none will arc.  

Hum can be induced by many different things so that is a whole other topic.
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Lord Soth
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Re: Lots of problems with my CSP2+
Reply #3 - 06/05/12 at 13:47:40
 
Dear Mad Dude,

Sorry to hear that you have so many issues with your unit.

I have rolled many types and brands of tubes and my unit is both HUM and hiss free. The weakest tube I rolled in the sensitive input tube position had only 50% emission life left and it was still hum and hiss free.

Here are some suggestions I can think of

1. Power Plug
I'm using a cheap but effective power plug (Belkin brand) which cuts out all kinds of RF noise from the power lines.
Air-conditioners and refrigerators contribute to the power line noise and this simple and cheap plug works for me.

2. Ground loop
I'm no electrician but this might be the source of your problems.
http://www.epanorama.net/documents/groundloop/

3. Tubes
Do you still have all those problems even when running on all stock tubes from Decware?

I understand that every unit is tested with the stock tubes. So you really have an unusual problem.

If you don't want to send your unit in for repairs, here's what I suggest. You need to get hold of a very good and reliable tube dealer.
I can recommend 2 tube sellers who test their tubes extensively. Be sure to ask them for low noise non-microphonic tubes.

Kevin Deal
http://www.upscaleaudio.com/6922/

Brent Jessee
http://www.audiotubes.com/6dj8.htm

If you still have problems with those tested tubes, then your CSP2+ might really have a problem.

Best Regards

LS
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Mad Dude
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Re: Lots of problems with my CSP2+
Reply #4 - 06/05/12 at 17:12:59
 
Thanks for your replies everyone!
I will try and contact Steve Deckert and ask if he has any advice.

Regarding the humming, I guess I will not be able to get rid of that - I live in an apartment in a ~ 40 years old house, and some of my neighbours have really old refrigerators and other old electrical devices, which probably introduce problems with the AC power. Perhaps I will try an AC filter and see if this brings an improvement. The only weird thing is that I used to have other audio equipment, among it some tube amps, and none of them exhibited this amount of humming.
Anyway, I could actually live with the humming - but not with the hissing and/or other, irregular noises. These are really disturbing and clearly audible in music with quiet passages.

In any case, if the only solution is a check-up for the amp I will of course send it to Decware. But since shipping the amp to the US and back, plus import taxes, can easily cost me $350 or more (ouch!), I try to make sure if it actually is the amp that has a problem and not something else.
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Lon
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Re: Lots of problems with my CSP2+
Reply #5 - 06/05/12 at 17:24:34
 
One other thought. . .are you using unshielded interconnects? If so, try using a pair of shielded. I have found hum in my system because of unshielded interconnects before, too close to power cords, transformers, etc. I have one pair of shielded (Audioquest Silver) interconnects I had to dig out to use between a turntable and a phono preamp this week, forgot how essential it is to have shielded interconnects there.
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« Last Edit: 06/05/12 at 20:01:01 by Lon »  

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Mad Dude
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Re: Lots of problems with my CSP2+
Reply #6 - 06/05/12 at 20:57:08
 
I proudly use the cheapest generic interconnects I could find. They don't sound quite as good as coat hangers but are so much more convenient to use. On a more serious note, my problems are not related to the cables - I have tested the amp without any cables connected except the power cord and headphones, and the problem persists.

Today I also disconnected every electric device in my apartment (except basic household devices like refrigerator etc), then connected the amp directly to a wall outlet (without any extension cable or power strip in between). Unfortunately nothing changed.
I'm getting more convinced that the amp itself is the problem. I have again tried swapping some tubes but the problems are always the same (always the same channel, same volume).
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Lon
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Re: Lots of problems with my CSP2+
Reply #7 - 06/05/12 at 21:08:42
 
Best to seek advice from Steve then. I hope that the easiest possible fix is the one that is needed.
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deucekazoo
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Re: Lots of problems with my CSP2+
Reply #8 - 06/05/12 at 21:50:55
 
Did you say crackling?
Just an idea here. I have an older CSP2 that has the adjustable output volume controls. Mine went bad to the point that just a little turn they want loud and yes I had loud crackling and just bad sound. I replaced them with some stepped volume controls and all is fixed. I can't remember if I had hum issues but I would check those volume controls out. I guess the quckest fix would be to get a electrical cleaner spray an see if you can clean them. If the sound just get a little better then you know its them. Just something else for you to check.

John
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Mad Dude
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Re: Lots of problems with my CSP2+
Reply #9 - 06/07/12 at 18:31:30
 
Thanks for the suggestion John. I'm afraid though that my problems are not related to the input pots, at least there is no change at all if I adjust them (I suppose the crackling/hum/hissing would change at least a little bit if the pots were the culprit).
Anyway, I will wait for a reply from Steve Deckert. I do hope that my problems can be solved - I have another headphone amplifier (solid state) which is perfectly capable of powering my headphones, but lacks the very pleasant coloration which the CSP2+ provides. :-)
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Steve Deckert
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Re: Lots of problems with my CSP2+
Reply #10 - 06/08/12 at 16:14:02
 
Hissing, ticks, crackles and all related noises are typically tubes.  Hum, while less or more with certain tubes is likely the unit itself.  A certain amount of hum is expected.  At this stage of the game it would be helpful to know what specific headphones you are using so I can examine the efficiency.  Some phones are as much as 12dB more efficient than others, so it's possible for one guy to have no hum and the other guy to have some hum based on the difference in efficiency.

I thought I read you mention something about "always on one side" can you expand on that a bit more?

Steve
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Mad Dude
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Re: Lots of problems with my CSP2+
Reply #11 - 06/08/12 at 18:21:21
 
Steve, thanks for your reply.  :-)
I would think as well that the tubes are the problem; but I cannot believe that all of my tubes are faulty - the problems are the same no matter which tubes I try.
I have to repeat, I can live with the hum. The real problem is the hissing/crackling which is driving me insane...

I will try to explain about the hissing/crackling: I only get this in one channel (the left one), it never changes. Swapping the tubes does not do anything. Also, it is not related to the input (source) - the issue stays the same even if no interconnects are installed.

Also, I have to add that the hum and the hissing/crackling do not seem to be connected. The hum is "stable" on both channels and only changes in intensity when new tubes are installed (6922 hum a bit less than 6N1P).
The hissing/crackling is only in the left channel, it intensifies over time: After plugging in the headphones (I usually let the CSP2+ warm up for about 5-10 minutes before that) I get a few seconds of silence (except hum), then the hissing starts, first only faintly, then grows stronger after half a minute or so. After one or two minutes, it is quite loud and then it develops into a crackling noise, which then gets louder as well. The crackling sounds a bit like ripping apart a piece of cloth or felt.

Regarding headphones, I mostly use the Sennheiser HD600 (300 Ohm / sensitivity 97 db/MW). I also have a pair of Fostex T50RP (50 Ohm / sensitivity 97 db/MW) and a Beyerdynamic DT1350 (80 Ohm, don't know the sensitivity) though I rarely use these two with the CSP2+.
It is noteworthy that with the T50RP I get almost none of the issues described - there is only a slight hum and nothing else. With the DT1350 it is almost exactly the same as with the HD600 (hum, hissing and crackling).
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Steve Deckert
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Re: Lots of problems with my CSP2+
Reply #12 - 06/09/12 at 04:07:48
 
OK, Next we need to see if we can cause the hissing and crackling to change by wiggling tubes, wiggling input and output pots, wiggling headphone jack.  

Steve
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Mad Dude
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Re: Lots of problems with my CSP2+
Reply #13 - 06/09/12 at 16:54:27
 
I've tried wiggling around everything, but nothing changed. In the meantime I've also cleaned the tube sockets, but unfortunately the problem persists.

Interesting side note: Yesterday evening, just after I made my last post, I switched the amp on for an hour or so, and this time the crackling was greatly reduced (the hissing was still there however). But today the crackling was back in full strength...
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Rivieraranch
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Re: Lots of problems with my CSP2+
Reply #14 - 06/09/12 at 18:31:26
 
I'm not the one to say but it sounds more like tube problems than anything else.
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