LYNX amp problems...Help

[Jan Dupont]

Thanks 🙂
I have just emailed you the datasheet for the non-polarity caps 😉

 

[li_gangyi]

Where did you get them??
I need to find some...I know RS carries them...but I hate their delievery charge...often it's higher than the stuff I get...unless I plan to get some trafos from them...

 

[JojoD818]

Jan,

Thanks for the upload! I got my copy just now. I see that you used 340/350 as the predrivers instead of the 15032/33 pair. Anyways, thanks man! 😎

JojoD

 

[Jan Dupont]

li_gangyi
These are from RS.
However you can use normal caps instead of the NP-Caps😉

Jojo
My component list are only suggestions!!!!
It works fine with both types

We have just has a major Power Down (6 hours) on the electricity net here in eastern Denmark and southern Sweden, so I won't be able to upload more today.
However I hope to be finished tomorrow (if the electricity don't fall out again )

 

[li_gangyi]

I assume the positive of the caps will be the thinner line of the cap...am I right??

 

[Jan Dupont]

If you are not using NP-caps but "normal" caps, you should use two to make a Non-Polarity cap 😉
If you connect the two negative terminals on two normal caps together you got a NP-Cap
Like this:

lead------ (+ cap -) -----lead----- (- cap +) ------lead

 

[UrSv]

Sorry to barge in here but ACD, would it be possible to bridge the amplifier?

Thanks

 

[li_gangyi]

Yeah I know that trick ACD...but that would mean I would need tow caps that are twice the original Value...in this case series connecting 2 44uF caps will give me a NP 22uF cap...as for the bridging problem...I think that's perfectly possible...just use a simple opamp circuit to "split-up" the sound signal and apply it to 2 amps...and then jion both speaker wires to the positive of the amps...remember not to ground any side...

 

[Jan Dupont]

Welcome to UrSv
Yes! This amp is perfect for bridging. You just need a seperate circuit with an Opamp and 4 10K resistors to invert the signal to one of the amplifier circuits🙂

Li:
The value of these NP-caps are not so important, as they only goes into action, when the current limiter circuit strikes.
I wonder why it is so difficult to get NP-caps where you live

 

[sajti]

Hi all,

I finished Yesterday the LINX amp. It has really good bass, and can drive anything down to 2ohms.
I used MJL21193/94, MJE15030/31, and MJE340/350 for the output stage.
I made some modification, as I add DC servo for the circuit and I used NE5532 for input and DC servo application.

Sajti

 

[Jan Dupont]

Sajti

Always nice to hear a respond, when people build your stuff 😉
Congratulations and thanks 😉

Yes! DC-servo can be used, however I have observed a weaker bass response when using DC-feedback and servo's.
As this amp amplifies DC, it's necessary to use a very low DC-offset opamp

The first version I made used a DC-offset trimmerpot to on pin 3 of the opamp, to remove the DC-offset🙂

 

[sajti]

I had no problem with the bass. I set the DC servo frequency to 0.2Hz, and I use 2nd order filter, to avoid bass cut, and noise.
The output DC offset was less than 1mV over hours.

Sajti

 

[Jan Dupont]

sajti

Well done

 

[peranders]

Jan (ACD), note that you have written mH instead of microHenry for the output filter. Also, this "L" can usually be 0.5 uH - 2 uH, not very critical.

 

[li_gangyi]

I'm not so sure why I cannot find NP caps here easily...other than from RS...which costs a lot to ship here...so I'm just taking an easy way out...hehe

 

[Jan Dupont]

Peranders

Thanks😉
Will be corrected a.s.a.p.

 

[Jan Dupont]

li_gangyi

How?? 🙂

 

[li_gangyi]

What you mean by how...I'm still waiting for my PCBs....haha

 

[Jan Dupont]

I emailed the PCB-files to my supplier yesterday😉
I better give him a call🙄

 

[li_gangyi]

Wonder if my stuff has reached you already...lolx...😎