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Background noise when connecting Amp to Pre-amp

richiesgr

richiesgr

New Member
Hi
I've received as a gift a turntable from my children.
My amps is a Onkyo NR474 not really a musical amps and doesn't have a PHONO input.

So I brought a PHONO pre-amp FOSI BOX-X4 with tube

I connect the pre-amp to CD or PC input in the amp and connect the turntable to the pre-amp so far so good
BUT

I hear a strange click sound + high background noise + low volume (I need to push the volume of the pre-amp to max to barely here something)

This occurs when I connect the AMP to pre-amp EVEN when the turntable is disconnected.

Regarding grounding
The turntable come with 2 mode phono or line (I'm using the phono)
There is no grounding anywhere in the turntable
There is no grounding in the ONKYO
The pre-amp have a ground terminator

I've try to ground the AMP by connecting a wire between a screw to the pre-amp ground terminator it doesn't change nothing I got the exact same noise
I'm posting the recording I made from the speaker to give you an idea The most problematic are the clicking noise of course

Thanks for any help
 

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That must be a hybrid design of some sort. The 5654 is a single pentode, not sufficient by itself for the functions claimed for this preamp. And at $90, well, you get what you pay for. I would return it and try a different model. If this is your budget, you'll probably have better luck with something all solid state.

Jack
 
TriodeLuvr said:
That must be a hybrid design of some sort. The 5654 is a single pentode, not sufficient by itself for the functions claimed for this preamp. And at $90, well, you get what you pay for. I would return it and try a different model. If this is your budget, you'll probably have better luck with something all solid state.

Jack
Click to expand...
Yeah I hoped for another answer but you probably right.
You also right it's an hybrid at 90$ so for you all the components are OK they just don't fit together ?
Thanks
 
TriodeLuvr said:
That must be a hybrid design of some sort. The 5654 is a single pentode, not sufficient by itself for the functions claimed for this preamp. And at $90, well, you get what you pay for. I would return it and try a different model. If this is your budget, you'll probably have better luck with something all solid state.

Jack
Click to expand...
I have a small line level preamp/headphone Amp that uses those tubes.
It is a hybrid. It has a single ended SS output stage.
 
If the turntable has two output settings; line and phono, it has an onboard phono preamp. By using the phono output into a phono preamp you're applying the RIAA curve twice to the signal. You are essentially putting two phono preamps into the signal. Try the line output setting on your turntable or try the phono setting without the external preamp. Also try the Pure Audio Mode on your Onkyo. It should improve the sound quality from your turntable significantly.
 
It's not really a stand alone phono preamp is it? It's a preamp with a MM phono stage. You really just need a stand alone phono preamp. There are options in the same price range of that FOSI. Just plug a phono preamp into an aux input on the Onkyo. When it comes to phono preamps personally I'm not picky when it comes to it being SS or tube. It just has to sound good and be quiet.
I was acually surprised by the ultra cheap Pyle 999 phono preamp. While it's really cheap, it was dead quiet and didn't sound horrible. I bought it to use in a second system until I was done building a really nice SS phono preamp.
The Pyle was acually listenable. For around $100 there are much better options like the Pluto, etc.
 
richiesgr said:
You also right it's an hybrid at 90$ so for you all the components are OK they just don't fit together ?
Click to expand...
I think the problem here is more fundamental than that. No company can produce a quality tube-based phono preamp anywhere near that price. The 5654 was likely chosen for this product because it's a fairly inexpensive tube and (as far as I know) hasn't been commonly used for audio. This is a frequent strategy for bottom-feeding Chinese companies. But even with that, other components add significantly to the cost of a tube design unless they are very poor quality. It's just not the best route to take for what you're doing.

Jack
 
dcgibby said:
If the turntable has two output settings; line and phono, it has an onboard phono preamp. By using the phono output into a phono preamp you're applying the RIAA curve twice to the signal. You are essentially putting two phono preamps into the signal. Try the line output setting on your turntable or try the phono setting without the external preamp. Also try the Pure Audio Mode on your Onkyo. It should improve the sound quality from your turntable significantly.
Click to expand...
I've done this put the turntable on PHONO and connect to PC AUX input and no noise at all I was not aware also about pure audio mode it's working good now.
I stay with these FOSI tube pre amp and don't know what I'm supposed to do with it
Ideas ?

Thanks for your quick help
 
richiesgr said:
I've done this put the turntable on PHONO and connect to PC AUX input and no noise at all I was not aware also about pure audio mode it's working good now.
I stay with these FOSI tube pre amp and don't know what I'm supposed to do with it
Ideas ?

Thanks for your quick help
Click to expand...
@dcgibby is spot on with his suggestion. You were doubling up on phono preamps by using the one in the turntable feeding another phono preamp.

If you want to use the Fosi unit, set your turntable to line out mode and plug it into the Fosi MM input. Then plug the Fosi output RCAs into your Onkyo AVR. If the noise still exists with this connection setup you probably have some noisy Fosi tubes.
 
BmWr75 said:
@dcgibby is spot on with his suggestion. You were doubling up on phono preamps by using the one in the turntable feeding another phono preamp.

If you want to use the Fosi unit, set your turntable to line out mode and plug it into the Fosi MM input. Then plug the Fosi output RCAs into your Onkyo AVR. If the noise still exists with this connection setup you probably have some noisy Fosi tubes.
Click to expand...
So you think it could be also that this noise come from a defective tube in fact after checking they've not send me the 5654 tube but something like "6m2 electronic tube" (quote).
Is it worth trying to get a new pair of tubes or not using this pre-amp at all ? because it's not really meant to be used with this kind of turntable
Thanks @BmWr75 @TriodeLuvr
 
I would just return the device if it's still an option. Regardless, I would forget all about using it- either put it aside or give it away to someone.

As a general suggestion, please be specific as possible upfront about equipment (ie, make and model number) when asking for technical advice. :thumbsup: It'll save a lot of guesswork.

Glad you got it sorted out.
 
richiesgr said:
So you think it could be also that this noise come from a defective tube in fact after checking they've not send me the 5654 tube but something like "6m2 electronic tube" (quote).
Is it worth trying to get a new pair of tubes or not using this pre-amp at all ? because it's not really meant to be used with this kind of turntable
Thanks @BmWr75 @TriodeLuvr
Click to expand...

If you don't need it, I would not put it in the signal chain. My approach as I've gotten older is to keep it simple as possible.
 
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