DIY ACA mini

[baeijsman]

@zm: Thank you! I absolutely know not what I'm doing.
...but this I would adjust to a third Iq for each pair, to reach same total as original.
... and I would of course have to find 4 very closely matched triplets.

 

[Zen Mod]

what exactly you expect to achieve?

 

[baeijsman]

A tiny increase in damping factor.
...and I'll probably sleep better!

 

[Zen Mod]

I'm not so sure that you'll get increase of DF, that way .....

 

[baeijsman]

Damn! I would have loved to build that, but hey, it was just an idea.
Thank's ZM.

 

[e_fortier]

Would increasing your negative feedback increase your DF ?

 

[Zen Mod]

in general , yes

 

[Nelson Pass]

Damn! I would have loved to build that, but hey, it was just an idea.
Thank's ZM.

But it's an idea. I think you should try it and see.

(That's what I do....)

 

[lastnamenelson]

FYI: I just added a long post to my ACA Mini Listening Impressions thread. I report that my ACA Mini sounds fantastic with the bias set properly. @Nelson Pass says the bias current "wants to be at 350 - 390 mV."

https://www.diyaudio.com/community/threads/aca-mini-listening-impressions.401953/post-7482475

 

[Zen Mod]

I'm not so sure that you'll get increase of DF, that way .....

A tiny increase in damping factor.
...and I'll probably sleep better!

my apologies


you got it right - I was mentally in another thread, where my reply is appropriate

ZM Omniconfused

 

[baeijsman]

@zm: Don't apologize. Omnicity is a skill!

@papa: Thank you. I will proceed!

Next step is to buy a truckload of 520's and 9520's and start measuring.

 

[dieter12]

I had a discussion with Carsten (CW) about more output devices. Why not use IRDF240/IRFD9240 and more bias?
Dieter

 

[Mikerodrig27]

Would you want to lower the source resistance?

 

[dieter12]

yes 0,22R ?

 

[Mikerodrig27]

Sure, but 0.47 seems to be the typical value for IRFP240/9240

 

[Mark Johnson]

You can modify the circuit of post #2392, add zero new components, and reduce C4 by a factor of 10X. From 1000uF to 100uF. Reducing parts cost and board area.

Disconnect and move R3 so it is now in parallel with C4. Modify the values of R3 and R4. Change C4 to 100uF. Done.

 

[WBS]

Should this discussion move to its own thread so as not to clutter this one for those sticking with the original Mini from the store?

 

[Mikerodrig27]

It may get more filtered attention in it's own thread. Maybe just post a link here.

 

[Stanislav]

I had a discussion with Carsten (CW) about more output devices. Why not use IRDF240/IRFD9240 and more bias?
Dieter

You can but then you are in F5 territory (bias, Ciss, Qg, etc.) and better off building F5.

 

[WBS]

Plus a new F5 will be showing up in the store SOON!