Dx Blame MKIII-Hx - Builder's thread

[meanman1964]

In the seventies american cars had theire positive battery pole hooked on the chassis of the carbody.JBL had woofers in that time the red speaker connection as negative and the black connection as positive.When you hook those driver on a todays amp and don't turn the connection the cone will move inverse.I think that's why it is important how you wind your coil.

[canonnica]

I'm not sure to get it completely, but is it only relevant when the resistor is located in the core of the coil?

[a.wayne]

Why have the coil , is this the possible slewing we see on canonnica's amplifier can it be removed ?

Anyway Merry Xmas guys , Joe check under your tree , only 24 as requested ..

[evette]

Wayne I believe this coil has something to do with possible ringing of the amplifier at or above 200khz,, It,s acting as a damper . It also helps to stabilize the amplifier. Also reduces the damping factor. My christmas tree died I forgot to give it water. Joe

[meanman1964]

The most important thing is BMW850 didn't find his MKIII sound nice and after he rewind the coils he said the sound improved.There are some things we can't explain and maybe it's good to have some basic rules like how to wind your coil even if it's just for your peace of mind.

[bonfis]

Originally Posted by BMW850

I have the coil on my MKIII on the right way wrapped as Patrick and Hugh Dean suggested and that is a whole improvement.
I had the coil wrapped the wrong way, see #1462

Patrick, thanks for the right solution
Dx Blame MHIII Hx: https://www.youtube.com/watch?v=AHp82_KWuTQ

Regards,
Rudy
Merry Christmas

I'd sure like to hear some technical explanation for why this would make any difference. I have used lots of commercially produced air core inductors (for example in xover networks) and have never seen one marked for polarity or any other indication that they need to be wired into a circuit with a particular orientation. The case of speaker coils is not analogous since they sit in the field of a permanent magnet that has a definite polarity. Air does not have a polarity and neither do resistors.
Steve

[meanman1964]

It had something to do with the input and output of the coil.I've ask Hugh Dean to give an explanation here.I've checked different commercial amps and all the coils are winded the same direction as I stated.

[DAMANHURI]

Originally Posted by SERGIODS

-please, upload all information is the PCB, that looks great. -

where can I get for this PCB layout?

[destroyer X]

to the main thread where the amplifier is shown first time....and there you will have layout to etch the pcboard at your own home.

regards,

Carlos

[bonfis]

Originally Posted by Vostro

I've attached a pdf I put together for you, it's based on a example from Bob Cordells book, but I added as much detail as I could to make it an easy read.
Theres abit of maths, but very basic and only basic electronics knowledge needed, The formula can be taken as standard.
The circuits from D. Self arent always complete, since he deals with principles of the amplifier one stage at a time.


Kind Regards,

Thank you Vostro for taking the time to put together this information. I do understand the concept of emitter degeneration as a method of improving the linearity of an amplifier. There is however some debate about whether this applies to the VAS given its function as a transimpedance amplifier. There is also some evidence that emitter resistors in the VAS stage actually increase distortion. The attached link describes this research in great detail.


http://www.sg-acoustics.ch/analogue_...n_comments.pdf
Thank you again for your kind response.