First One - mosFET amplifier module

[Lazy Cat]

Wow! Looks great!

Beautiful...

Beautifull job.

...As usual...

Thanks guys.

It takes two day's working time and it's finished, for some ultrafast DIY-ers one day at most.

 

[Lazy Cat]

Do you have young children ?

I like it to be hidden still within reach of a finger.

 

[quan]

OK then, First One having 0,3 uH output inductor only, so try to put extra 0,5 uH parallel with 2,2 Ohm/2 W resistor (serial output RL filter) in series with positive output wire. Normally amps having serial output inductor ranging from 0,5 - 1,5 uH. Impedance in this case should change enough (higher with freq) to prevent any unwanted effects.

Hi LC. I have soldered extra inductor of 0.6uH on positive speaker out. There is no noise when power up on its own but there is pulsating noise when connect with preamp. Do i need more inductance you think or problem elsewhere?.
Quan

 

[Lazy Cat]

Hi LC. I have soldered extra inductor of 0.6uH on positive speaker out. There is no noise when power up on its own but there is pulsating noise when connect with preamp. Do i need more inductance you think or problem elsewhere?.
Quan

Elsewhere. Probably grounding issue. What kind of alien preamp you own, according to battery spk cables.

 

[quan]

Elsewhere. Probably grounding issue. What kind of alien preamp you own, according to battery spk cables.

The preamp is Herron Audio tube pre VTPH-3a model. BTW the speaker cable is not actively shielded. I don't think it is a grounding issue as the noise sound different to ground hum or buzz. The noise is of higher frequency not hum or buzz.
Quan

 

[Lazy Cat]

The preamp is Herron Audio tube pre VTPH-3a model. BTW the speaker cable is not actively shielded. I don't think it is a grounding issue as the noise sound different to ground hum or buzz. The noise is of higher frequency not hum or buzz.
Quan

Any pic of assembled amp? If you connect one channel only, is there the same issue?

 

[quan]

Any pic of assembled amp? If you connect one channel only, is there the same issue?

Hi LC, amp power on without interconnect- no noise, with both interconnect -noise, one chanel only- no noise. Grounding issue?. Perhaps i should try ground loop breaker as you suggested.

 

[quan]

Hi LC, installed the ground loop breaker using 10R/0.1uF/bridge rectifier as per ESP web site but the noise remains.
Quan

 

[tubo]

quan,

Hope this helps,

regards

 

[quan]

quan,

Hope this helps,

regards

Thanks Tubo, did try ground loop breaker but not successful.
Quan

 

[androa76]

Maybe this will help you,

 

[Lazy Cat]

Thanks Tubo, did try ground loop breaker but not successful.
Quan

SMPS probably have GND connected to bolt pad and thus to chassis and that's not OK since loop is formed. Try to isolate both SMPS PCB fixing bolts and brake the loop.

 

[quan]

SMPS probably have GND connected to bolt pad and thus to chassis and that's not OK since loop is formed. Try to isolate both SMPS PCB fixing bolts and brake the loop.

Thanks LC, i will try that and let you know.
Quan

 

[BYRTT]

Hi LC, installed the ground loop breaker using 10R/0.1uF/bridge rectifier as per ESP web site but the noise remains.
Quan

Hi quan when trouble shooting finished you can try listening test LC's suggested loop breaker instead of the ESP one, to see if sonics improve in you setup as it did for LC and listening team. Here is link to post #838 http://www.diyaudio.com/forums/vend...e-mosfet-amplifier-module-84.html#post3940983.

 

[meanman1964]

Hi LC, installed the ground loop breaker using 10R/0.1uF/bridge rectifier as per ESP web site but the noise remains.
Quan

Disconnect the resistor and the noise is gone

 

[quan]

Disconnect the resistor and the noise is gone

I thought they meant to equalised the potential difference of small voltages?.
Quan

 

[meanman1964]

sometimes this resistor can cause a noise with certain amp designs
Just try it to see if the noise is gone if not connect it again

 

[irribeo]

Many SMPS's do produce noise. Many need to be shielded completely too.

 

[_henry_]

No noise from hypex's smps so far with smps600 and smps1200

 

[meanman1964]

I've tested a new SMPS brand as Beta tester together with the Fist One module.Amp module maximum 5 cm distance away from the SMPS no noise or what so ever.Maybe SMPS related could that be?