ACT2.2 distortion/pops?

[roberto]

And always the best way to a bad tube is to replace it with another with the same number or direct substitute. Never use a tube where it does not belong to the circuit design.

As AJ pointed out, I also had an intermittent small signal tube with noises and pops. The last one was on a VT-200 Audio Research power amp tube. Sometimes the right channel was making popping and a ppppprrrrrffff noise. Also the signal dropped -10dB, and suddenly started to work fine. There are five 6922 tubes on each channel. The tube tester did not find any problem with the bad one. So I started to swap them between channels. Then with one, the problem went to the left channel. That was it, a bad 6922.

Also in a CT-5 are two 6NH30 tubes connected in parallel. One 6NH30 was intermittent and doing unwanted noise.

Happy listening!

[Big Dog RJ]

Attn: HPfish

Checking on your noise issue with the ACT2... any further outcome? Any idea what was causing it?
Would be good to know so that others could take notes.

Best, RJ

[hpfish10]

I have not used the system awhile now and started auditioning this week. Of course the problem showed up. Now I need to go thru the troubleshooting steps again. I am swapping the L/R source signal from ACT2.2 to 350 to reconfirm if it's the ACT2.2 issue. Will keep you posted.

[hpfish10]

I started to listen to my system last few days. It played well couple of days then the loud pop and distortion noise returned. I swapped new tubes out and put back the old set of tubes, still have problem. As stated the pop/distortion was on the left channel, I swapped L/R output cables to my CJ 350 amp, the problem moved to the right channel, and persists even with no input signal or different source signals. I think the left channel is the culprit. Any ideas? I will need to contact Conrad Johnson to ask them for advise for next steps.

[admin]

Sounds like it's not a tube issue. I don't have a schematic for the ACT2 so going pretty blind here. I would go with the low hanging fruit. Very thorough visual inspection of the left channel components looking for any burn marks, bulging caps, poor solder connections, etc... Next I would get a non-conductive pencil length stick/rod, and while the unit is on, very carefully apply gentle pressure to components to see if there is a cold solder joint that may be the culprit if you can reproduce the pops/distortion.

Again, not very specific I know, but without schematics and in depth knowledge of the ACT2 design, that is where I would start. Of course Jeff at CJ could surely fix it but that will obviously cost a bit (which would not be a waste in my opinion as you would have a refurbished unit that you know was "done right").

[Big Dog RJ]

That's the best advice by Admin.

Also just to add, unless you had a local techie who's familiar with this design. The ACT2 is actually bit complicated and cumbersome to work with, since it's a dual chassis design.
The sub-chasis floats on a second level, based on a suspension system of some kind, and that config is not easy to access.

My very skilled CJ techie took nearly a whole week to figure it out, carefully step by step, and he's been servicing CJ gear since the Premier line commenced. Of course once he sorted it out, it never had any problems. Also, the new owner whom I sold it to, hasn't encountered any issues as yet, so far so good.

Good luck with it, and let us know how you go.
Cheers, RJ

[Joe Appierto]

The Premier 16LS used a similar sub-chassis system. You could feel the give when changing tubes. I don't remember any more whether the same held true for the Premier 17LS.

[hpfish10]

I played it 8hrs yesterday and so far no issue, so it will be difficult to fix this intermittent problem.

[hpfish10]

Update: I discovered the left channel cable (Purist Audio) from preamp to amp was connected in reverse and not as the manufacturer’s directional intention. Hopefully that is the culprit, I will need to play more hours to confirm.

[roberto]

Hola,

With much respect, a cable connected reversed mode cannot produce pops and odd noises. Yes, play more hours to make sure who is the culprit on your preamp. Usually odd noises are due to a small signal tube.

Let's think that the position of the tubes are like a clock dial face. Tubes 9 o'clock and 6 o'clock belongs to the left channel and 3 o'clock and 12 o'clock tubes are the right channel. First swap the 6 o'clock for the 3 o'clock. If the noise is still on the left channel, then swap the 9 o'clock for the 12 o'clock. This is my assumption and I could be wrong with the tubes channel position, then if the noise is still on the left channel. Swap the 9 o'clock for the 6 o'clock and then 12 o'clock for the 3 o'clock.

Perhaps this could track better for a noisy tube.

Happy listening!

[admin]

I also don't see how a cable direction would cause these issues, unless the cable was not seated properly to begin with and simply removing and reconnecting made a better contact. Or a cold solder in the connector and reseating the cable simply pushed it to a better contact.