KG CFA3 headphone amp
Mar 18, 2021 at 7:16 AM Post #106 of 1,794
Hi.

Would you possibly know of how small a CFA3, and of how small a Dynahi, possibly could be made?
Going to SMD components would let you shave at least 30-50% of area mostly by shrinking resistors. TO-92 board footprint isn't much smaller than SMD transistors and board width will be determined by heatsinked output transistors. I dunno, maybe some layouting wizard could make it flat mountable on a 2U heatsink. The problem is that many DIY'ers are afraid of SMD parts.
 
Last edited:
Mar 18, 2021 at 8:01 AM Post #107 of 1,794
Going to SMD components would let you shave at least 30-50% of area mostly by shrinking resistors. TO-92 board footprint isn't much smaller than SMD transistors and board width will be determined by heatsinked output transistors. I dunno, maybe some layouting wizard could make it flat mountable on a 2U heatsink. The problem is that many DIY'ers are afraid of SMD parts.
Thank you for your suggestion for what might be possible for making those amplifiers smaller.

Why are many DIY builders afraid of SMD components?
 
Mar 30, 2021 at 5:18 PM Post #109 of 1,794
Thank you for your suggestion for what might be possible for making those amplifiers smaller.

Why are many DIY builders afraid of SMD components?
Not necessarily afraid of them. I've built around 5 of the SS Mini Dynalos, which are pretty much all SMD. The problems with SMD include the difficulty in troubleshooting them, parts removal/changeout (depends on device footprint), problems with matching devices (resistors/transistors), etc. An amp done with all SMD will also tend to run hot. Looking at you mini dynalo :) Just because the amp board is done SMD doesn't mean the heatsinking and thermal requirements will decrease.
Packages such as the QFN-20 are in my opinion dumb. Try soldering one of these to a 2 or 3oz copper board, with half the pins connected to ground. Good times.
 
Mar 30, 2021 at 6:07 PM Post #110 of 1,794
Not necessarily afraid of them. I've built around 5 of the SS Mini Dynalos, which are pretty much all SMD. The problems with SMD include the difficulty in troubleshooting them, parts removal/changeout (depends on device footprint), problems with matching devices (resistors/transistors), etc. An amp done with all SMD will also tend to run hot. Looking at you mini dynalo :) Just because the amp board is done SMD doesn't mean the heatsinking and thermal requirements will decrease.
Packages such as the QFN-20 are in my opinion dumb. Try soldering one of these to a 2 or 3oz copper board, with half the pins connected to ground. Good times.
Thank you for explaining those difficulties, that utilising SMDs provide.

Are there advantages to utilising SMDs, besides the smaller size of the piece of equipment that would be possible to be made from utilising them?
 
Apr 14, 2021 at 10:01 AM Post #112 of 1,794
Bumping this thread because I have some downtime while I wait for some parts to be cleared by the customs.
Have 2 custom CFA projects on my table at the moment. The larger one is a 3U case while the smaller one is 2U. Roughly the same spec as my previous builds but both are going to have some uniqueness to them, which I will reveal when they are finished. :)
What were the "uniqueness to them" from both of these builds? I never saw that across the remainder of the thread.
 
Apr 14, 2021 at 11:58 AM Post #114 of 1,794
The 3u build had speaker taps, and switch to go between speaker/headphone.
Did you or @Dukei expand if you increased the bias or anything else perhaps different?
 
Apr 14, 2021 at 12:02 PM Post #115 of 1,794
Did you or @Dukei expand if you increased the bias or anything else perhaps different?
I don't think he did? I personally have no idea. I just said make me pretty things that make nice sounds and send to me. So details are lost. Forgot to say small, and now it's pretty and big. Hopefully he can fill in the details.
 
Apr 14, 2021 at 12:10 PM Post #116 of 1,794
I don't think he did? I personally have no idea. I just said make me pretty things that make nice sounds and send to me. So details are lost. Forgot to say small, and now it's pretty and big. Hopefully he can fill in the details.
Haha. I love how you forgot to say make it small and now you have the largest build.

I'll wait to hear @Dukei respond.

The beauty of DIY is any ****ing way you want it. :grin:
 
Apr 20, 2021 at 9:28 AM Post #120 of 1,794

Users who are viewing this thread

Back
Top