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OLDER DECWARE GEAR SUPPORT >> CSP, CSP2, CSP2+ >> Decware noob, picked up a CSP2+ and have questions
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Message started by AssFault on 04/12/15 at 07:05:31

Title: Decware noob, picked up a CSP2+ and have questions
Post by AssFault on 04/12/15 at 07:05:31

Hi all , I just picked up a used CSP2+ to use as a preamp for my Dynaudio Monitors. Have a few problems/questions, hoping you all can help out. They are:

1. I hear an intermittent crackling noise in both speakers. It kind of sounds like a vinyl pop but I'm listening to digital files so it's not the recording. What could this be?

2. The kid I bought this amp from was twisting the gain pots like volume controls when he was demoing the amp to me. They don't appear to be factory marked and I was reading in the CSP manual how to set the output levels. It mentions how the factory calibration is set using a test tone and measuring input/output voltages. I have a DMM and test tones, can I do this myself? If so, how do I get a voltage measurement from the input & output connections? Do I use a 0db 1000hz test tone? Do I need a speaker connected to the output?

Thanks for any feedback, looking forward to getting this dialed into my system.

Title: Re: Decware noob, picked up a CSP2+ and have questions
Post by Syd on 04/12/15 at 09:45:32

Hi AssFault, congrats on the CSP2+, it`s a great tool for delivering the signal to your amp. The pre in/out volume pots are really trimmers to suit your ears so you can dial in your front end before using the main volume. Subtle differences which are lost on me, and I sometimes use the pre in/outs as master volume settings if I want to keep the main volume knob in one position. No problem in using them which way you want.
The only time I`ve experienced the intermittent`crackling` is when the power cord is just making good contact, and this can happen on any of my Decware amps. Yes they can seem a bit loose, it`s more a safety feature. They`ll come out easy if accidently knocked of a rack etc. You have to get them `just right`which can take a little time. Once done they`re no prob.
Of course there maybe another issue and the obvoius culprits, tubes, tube seating, i/c connections are ones that come to mind.
Dont know about taking voltage readings.
Hope it`s a small issue and you get glitch free sound soon.
Syd.

Title: Re: Decware noob, picked up a CSP2+ and have questions
Post by lLance on 04/12/15 at 14:34:17

The last time I had this problem I checked my cabling thouroly just to find it was an EL34 tube going bad.

Title: Re: Decware noob, picked up a CSP2+ and have questions
Post by will on 04/12/15 at 15:36:45

I get the concern about the volume pots, though I have never heard my own crackle without movement, and then not the stepped pots. I think the calibration is a setup and test thing and as Syd suggests, the pots are about user adjustment.

A good start point for the silver in and out pots might be 9 (one notch back from full open) on the inputs, and 5-7 for the outputs (say 6...four back from full open.) Especially on the outputs, this will modify the CSP OTL effect and sound density. Lower/leaner, less CSP effect, and higher, more. If you don't hear crackling with changing these then I would start by finding starting place where you get the best sound and use the front pot for volume. Does it crackle when you move it? Mine does now, but I never hear it in the music so have been lazy cleaning it. It may be time to clean yours??? I find it is good to explore the silver pots a bit now and then for ultimate sound. And what sounds best may change a little as you get to know the sound or with different tubes.

Also, I wonder if you have spare tubes you can check. Since the noise is in both sides, it may be the input tube. Or just a weak tube connection can cause crackle. Cleaning the tube pins and socket is something I do when I hear weird noises that seem tube related.

Title: Re: Decware noob, picked up a CSP2+ and have questions
Post by Lon on 04/12/15 at 15:44:54

Actually that sound described sounds as if the crackle may be coming from the input tube. . . .