Help Debugging Dumbleator

[mwdavis14]

Hi all. Just finished my first build, a C-Lator - Ceriatone's buffered effects loop. Plugged in to test. Works, but having it plugged in there is a hissing type sound added which is louder/quieter depending on the output volume. Unplugging the C-lator eliminates this hiss, so its certainly coming from the unit. Every now and then, you will also hear an isolated pop or crackle type of noise. There is a pop sound when either of the bright switches are toggled, or when the standby switch is toggled. Another odd thing is that if the unit is in the signal chain and it is switched to standby w/power still on, there is no appreciable change in the sound. However, if I unplug the instrument cable from the input jack (while the unit is still in standby) and then re-insert the cable, the situation changes & no sound will come through until the standby toggle is switched back to operate. I have considered that there may be an issue with the grounds and will be checking those, but that doesn't seem to account for all aspects of this picture.

I am completely puzzled. Can someone help? I've posted on the ceriatone forum as well, but as yet no responses.

Thanks in advance,
Mark

[M Fowler]

The pop and crackle noise tells me there are poor solder joints and I would recommend referring to the layout and checking all connections for good solder as well as correct wiring.

Is this the C-later kit or home brew?

[mwdavis14]

Thanks. I thought as much. Built from kit. Followed meticulously, so a poor solder joint slong the way is all that really made sense. I tried playing with it again and found that when I flip it into standby the sound coming through will gradually fade away, as though residual energy is being dissapated. There is an audible pop when power switch is turned off. All other switches & pots are quiet. If these afded points help narrow likely source points, please advise. Thanks in advance.
Cheers

[martin manning]

Post some good in-focus pics.

[mwdavis14]

I ran a continuity test across each of my solder joints and found one which appears to be bad - the one which grounds the coax running to the speaker out jack. Seems a logical place to inject noise yet account for the unit otherwise working well. I'm going to start by reworking that joint and if that doesn't solve it, I'll post pics. thanks to everyone who's chimed in so far. Much appreciated!

[mwdavis14]

I've checked continuity across all of my joints and they all test fine. The one I thought was bad (per my last post) was not. I simply forgot that the ground side of the coax should not have continuity with the inner core, so the connections on the coax was actually fine. Though the joints appeared fine, I did see a few which had a dull appearance, and I decided to go ahead and rework those. Plugged it back in and, basically same deal.

With the gain dialed low and the output levels on the c-lator in a moderate position, it runs quiet. However, if I dial up the gain or crank the output on the c-lator, the high frequency hiss is present. Crackling is now gone, though there is still a "POP" when I turn the c-lator off with the amp turned on.

Is this Hiss something that would be normal for a tube amp product of this kind? I've only ever used solid state - this is my first foray into tube. Pics to follow

[mwdavis14]

Attached are pics of the build. Joints all appear solid & shiny, and there is continuity across all.
As an FYI, I tested all components which were not pre-assembled (boards come pre-assembled from ceriatone) and they all tested good.

[mwdavis14]

more pics attached

[mwdavis14]

2 final shots

[M Fowler]

I can't see any obvious problems.

Are you connecting the Dlater as shown by the operating manual?

[martin manning]

The pop when switching off with the amp on is normal. Hiss can come from a noisy tube, resistor or cap. I would try different tubes first. There will always be some noise, but it should be low-level. You can connect half of the unit at a time to help isolate the problem, but recognize that the input-send stage has ~unity gain, and will be inherently less noisy than the return-output stage.

[mwdavis14]

Thanks much. I'll try changing the tube & following these suggestions. The unit is hooked up per the manual

[Structo]

You may be running your levels too high.

On my D'lator which I run a TC G Sharp reverb/ delay through, have the Send (drive) control about 1:00, the Return (in) at 1:00 and use the Output (Out) pot to control overall volume.

On the amp I have the Preamp volume at 1:00 and the Power amp at 12:00.

If you run those first two pots too high it will hiss.

Also high treble or bright switches can add hiss.

And as mentioned, it could be one of the three preamp tubes or the D'lator tube.

[mwdavis14]

Thx. You are likely correct. With the levels in that range it is pretty quiet. Hiss begins when levels are high. Thanks again for the courtesy of the replies