HELP! - Speaker hissing under all conditions

[waltschwarzkopf]

Hi guys,

I recently acquired a Phil Jones CUB II AG-150 BK amp in good condition. I had been looking for a two channel acoustic amp to us with my stick.

The amp has many features and all seem to work fine, the only problem is the continuous hissing, not humming. (hissing = hiiiiiiiiiissssss, humming = hummmmmmmm)

I tried it without any instruments plugged in, all knobs turned to 0, gains, volumes, master, everything and the hissing is still there.

Any ideas of what the problem could be and how to get rid of it?

Cheers,
Walter

 

[Gtrjunior]

Re: HELP! - Speaker hissing under all conditions

How loud is the hissing?
Does it make the amp unusable?

I think with any amp 100% silent is unrealistic.

 

[Jacew]

Re: HELP! - Speaker hissing under all conditions

It shouldn't make noise volume down.

Have you tried it in different house?

 

[ehdwuld]

Re: HELP! - Speaker hissing under all conditions

Solid state?

Aint the speaker

Signal , probably some loose connection or solder joint , leaking through

 

[waltschwarzkopf]

Re: HELP! - Speaker hissing under all conditions

How loud is the hissing?
Does it make the amp unusable?

I think with any amp 100% silent is unrealistic.

Loud enough to be annoying, quite enough to be "unnoticeable" when you're playing.

It shouldn't make noise volume down.

Have you tried it in different house?

Yes, I knew about this when I bought it. Therefore the deal, 100 bucks for it. I hissed at the guy's house and hisses at mine. I tried also different cables and also by removing the center pin (ground) from the power outlet.

Solid state?

Aint the speaker

Signal , probably some loose connection or solder joint , leaking through

I believe it is SS. I was gonna remove the speakers and check for loose connections, but I guess is not needed, right? Where should I check for a loose connection or solder joint?

 

[ehdwuld]

Re: HELP! - Speaker hissing under all conditions

If it hisses with the volume down
I would think something around the output transformer has a bad solder joint
The hiss is the small arc of power passing over the gap

That would be where I'd start

Oh wait
Does it have an effects loop

Jump that with a patch cable first

 

[waltschwarzkopf]

Re: HELP! - Speaker hissing under all conditions

If it hisses with the volume down
I would think something around the output transformer has a bad solder joint
The hiss is the small arc of power passing over the gap

That would be where I'd start

Oh wait
Does it have an effects loop

Jump that with a patch cable first

Good idea, although I tried it and it was still hissing. I guess I'll have to open it and and check the output section to see if there is any apparent problem.

 

[waltschwarzkopf]

Re: HELP! - Speaker hissing under all conditions

Another thing. I tried using the headphones output and sound (guitar) comes out of the headphones and the speaker is muted (as it should). However, the hissing continues to com out through the speakers but no through the headphones.

Are the speakers the problem? I can remove them and have a quick look if there is anything wrong there. Also, since the amp is SS, I could turn it on with the speakers disconnected, right? This way I can see if the hissing actually comes through them and not some other part.

 

[ehdwuld]

Re: HELP! - Speaker hissing under all conditions

I think the headphone uses a different tap on the output transformer

 

[dystrust]

Re: HELP! - Speaker hissing under all conditions

I think the headphone uses a different tap on the output transformer

The amp is SS, so it probably doesn't have an output transformer.

Like others have said, I seriously doubt that the speaker is the cause here. And I agree with ehdwuld that the source of the hiss appears to be after where the headphone signal is tapped off.

 

[Jacew]

Re: HELP! - Speaker hissing under all conditions

Just a wild stab, but is the speaker grounded?

 

[waltschwarzkopf]

Re: HELP! - Speaker hissing under all conditions

Just a wild stab, but is the speaker grounded?

What do you mean by this?

The amp is grounded, as I'm using a three-pin plug to the power outlet. I can open the amp and remove the speakers to check them further, but what do I check exactly?

 

[Jacew]

Re: HELP! - Speaker hissing under all conditions

What do you mean by this?

The amp is grounded, as I'm using a three-pin plug to the power outlet. I can open the amp and remove the speakers to check them further, but what do I check exactly?

My Fender Mustang combo had a ground wire on speaker chassis to connect it to the amp chassis. I think it did made a slight hiss without it when I tried.

 

[NegativeEase]

Re: HELP! - Speaker hissing under all conditions

Phil Jones equipment has some pretty unique amp/speaker configs.. I suggest contacting Phil Jones, as if there ever was a company doing weird things -it's them.

 

[waltschwarzkopf]

Re: HELP! - Speaker hissing under all conditions

Ok! I’ll constant Phil Jones about the issue, seems like the first thing to do. In the meantime, I’ll have a quick look at the speakers and give it and try with the grounding.


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[waltschwarzkopf]

Re: HELP! - Speaker hissing under all conditions

My Fender Mustang combo had a ground wire on speaker chassis to connect it to the amp chassis. I think it did made a slight hiss without it when I tried.

I removed the speakers, and I have to say that those were the finest connections I've seen in any amp!

There was no ground to the speaker chassis, but also no way to do it, the whole cavity was made of solid wood and also filled with some woolly type of thing. I don't think they "forgot" the ground wire, there were only the + and - wires for each speaker.

 

[waltschwarzkopf]

Re: HELP! - Speaker hissing under all conditions

I tried again with headphones and the hiss becomes apparent if I crank up the volume, although I would never use it like this. Still, makes me think that he problem is not in the speaker, but somewhere else.

 

[ehdwuld]

Re: HELP! - Speaker hissing under all conditions

Ain't the speaker
There is no ground on any of my speakers

It may be a ribbon cable inside

 

[beaubrummels]

HELP! - Speaker hissing under all conditions

Do you have the limiter on? Try turning that off or turn it to 0. Otherwise, it could be that amp has some bad components in the output power section. It’s not speaker related. Hiss when volumes are down comes from the power section.

 

[waltschwarzkopf]

Re: HELP! - Speaker hissing under all conditions

Ok, then I’ll have a look at the output section. Should I look for anything in particular?

Glad to know that the speakers are not the problem. Although there was no hissing when the speakers were disconnected, I understand the hissing happens because some unwanted signal is coming from the output, right?


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