little noise with BOSOZ

[ralf]

Hi,
since ihave searched in the forum for sometihng about that, but nothing finding, i make this new thread:

I just have finished the prototype of my BOSOZ and connected it to my SOZ.

Now a little "ssssss" is hearable.
Might it be the parts?
I used IRF620. The Power supply and the BOSOZ circuit is original the one from Passdiy.

The only thing is i changed are the R1 -R6 Resistors. I used non Metal Types. Could this be the reason.

Other Question: can i use C1 -C2 as Paper in Oil capacitors for better sound?


THANK YOU VERY MUCH,

Regards,

Ralf

 

[grataku]

I have no ssssss's to report and I have used metal film resistors and the original mosfets.
When you say no metal resistor what do you mean? Did you use wirewound or carbon?
At what gain are you operating? Mine is 10dB.
I don't see why you shouldn't be able to use all the types of cap you want.

 

[Nelson Pass]

Keep in mind that power MOSFETs are not
very quiet. It could be that with a sufficiently
sensitive speaker you will be able to hear some
hiss, particularly with your ear against the tweeter.

Also, does the amp hiss with a grounded input and
no source? Does the combination hiss with the
input to BSOZ grounded and/or the volume control
all the way down?

 

[PassFan]

I was going to mention it but Nelson already has. I had some slight offset hum in my SOZs when I finished. You had to put your ear up to the speaker to hear it. Wound up coming from a modded CD player I changed an output chip in. I wouldn't have noticed it except I bypassed the blocking caps on the output.

 

[ralf]

Thank you, Mr Pass and Grataku

I used wirewound resistors, the "sss" is hearable only when i put my ear near to the tweeter, -yes the speakers do have a good sensitivity.
The "sss" is hearable when i use 10db gain ore more.

I should tell, that my Poti is in the CD Player ! with no balanced output.
Should i use a poti in the output of the BOSOZ???

Perhaps i use the original IRF610, and metal types.


regards,

Ralf