Tír Na HiFi

Just wondering if anyone out there has an Audio Note M Zero, just bought one which is NOS. But I'm a bit unhappy as its either not working properly or a total mismatch for the rest of my kit, as the noise level in my system has just shot up.

I run a CD-80 -> Beresford Caiman -> Audio Note -> Gainclone Monoblocks.

My monoblocks are normally quiet as a mouse, but now they sound like their playing a track of someone sweeping the street, well not quite, but you get the idea.

I am based in Cork, and would love if there was someone nearby who had similar kit so I could do an A/B and figure out the reality of my situation.

Any thoughts or suggestions are welcome.

Could it be the combination of a high gain preamp with highish gain power amps resulting in the noise?

Can you short the inputs on the preamp and see does the noise drop? Does it change with volume etc? Also, can you describe the noise too?


Fran

Fran wrote:Could it be the combination of a high gain preamp with highish gain power amps resulting in the noise?

Can you short the inputs on the preamp and see does the noise drop? Does it change with volume etc? Also, can you describe the noise too?


Fran

Hi Fran,

Thanks for the reply,

The noise does not change with the volume. I was listening away to the amp today while playing some vinyl and it was sounding really good, but like anyone who obsesses like we do, when you know there is a level of background noise present it just bugs you.

I would describe the noise as more of a hiss than a hum. I have a feeling you are right and that it could be simply the combination of a sensitive, high gain preamp with my monoblocks. When I run the monoblocks with just my beresford as pre there is pretty much silence, so hence my confusion.

Can you describe what you mean when you say short the inputs? Do you mean drop in some attenuators between pre and power?

Thanks,

Nathan

You'd need shorting plugs. The idea is that the input to the preamp is shorted (ie hot and ground connected together). This means that the noise you'd hear is from either the preamp or power amp or connection between the 2.

From what you're saying, it seems the noise is there with any source - which probably means that its the gain. You could try a set of attenuators between the preamp and power amp. Internet wisdom say that these affect the sound and kill dynamics, but I know of one member here who has tried them and they are happy with them.

I looked up the spec on the audio note zero and it says its 21dB of gain - probably about twice whats needed.

Can you do anything to attenuate within the gainclones?

(BTW, what gainclones are you running?)


Fran

Hi,

My gainclones are built using two mono LM3886 chip amp kits. Bought from this site: http://chipamp.com/lm3886-amplifier-kit/

I am sure there must be some sort of mod to attenuate the gainclones.

I've heard the same about attenuators between the preamp and power amp, so I'd rather not go down that route.

Nathan

If you DIYed the gainclones, you could add a resistor divider at the inputs to cut the signal coming in, you could even wire in a switch to do A/B test to see if there is any sonic penalty. The attenuators you'd buy do exactly this anyway. Something like 100k series/10k shunt might work?


One review of the Rothwell attenuators (not complimentary!):

http://www.enjoythemusic.com/magazine/e ... thwell.htm


Fran

I may need to run this thread through Google Translator.

Absolutely,that's given me a good laugh. I mean what are they actually talking about?

Yea, I read that article this morning, not complimentary at all. However, the guy did mention that better quality resistors might yield better results.

Gotta figure out how to do it though.

Nathan

Fran wrote:If you DIYed the gainclones, you could add a resistor divider at the inputs to cut the signal coming in, you could even wire in a switch to do A/B test to see if there is any sonic penalty. The attenuators you'd buy do exactly this anyway. Something like 100k series/10k shunt might work?


One review of the Rothwell attenuators (not complimentary!):

http://www.enjoythemusic.com/magazine/e ... thwell.htm


Fran

Put 100k in series with the hot, and then put one end of the 10k just after the 100k, with the other end of it to ground. You could do it all right on the input jack.

I'm saying this because I'm thinking you bought the kits and assembled yourself - if not do you have anyone near you who could solder them in without wrecking the amp?

Doesn't have to be exactly 100k and 10k either - probably the series one in the range 50-150K and the shunt from 5 to 30k would do AOK.


I went off and had a look at the LM3886. I didn't find the manual etc for your exact one, but did find one for another set of boards (the BrianGT ones also on chipamp.com - http://chipamp.com/docs/lm3886-manual.pdf). As they are all reasonably similar, the specs are undoubtedly similar. Anyway, it gives the gain on it as 35dB - a massive amount, and clearly meant to be made as an integrated or with a passive pre. It went on to say how you could change the gain on the boards by changing the value of one resistor.

***************************
Lads - very funny!!


Fran