SYMEF amplifier

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#743
Well 2 Symef pcbs are finished. Some "butique" parts but not much. I think they look like a million 🙂
Heatsinks will arrive tomorrow.. Still waiting for some insulation material and fuses. That will probably arrive on Monday..

So maybe I can get some sound next week or the week after?

Have attached a couple of pics..
 

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#747
nakamoomin said:
Hi. I used 1.2mm (16 AWG) Wound around a 12mm (1/2 in) core. I first tried 18 turns as suggested, but I got almost 2 uH on the meter. Then I tried 14 turns and stretched it out to ca 1 in (to fit the two mounting holes that are closest on the PCB). That coil measures close to 1 uH. Note that you have to drill these holes as they are a bit tight. Don't solder some thin wire to the coil to make it fit. This component will carry upwards of 20 Amp! (worst case) Don't skimp on the wire thickness. As long as the length, diameter and number of turns is the same, using 1mm shouldn't have a great effect. Just remember that you will get more resistance and thereby more heat.
Click to expand...

Please remember to check the continuity of the drilled pads 🙂
 
#751
I am not sure if I can wait until next week.. 🙂 Waiting for the last parts... (insulation pads for the transistors and fuses)

A couple of questions.

1. Diy transistor insulators.. Is it doable? Some tips would be great.
2. Has anyone tried smps on the Symef? I have one 48Vdc from MeanWell here.
http://www.meanwell.com/search/usp-500/USP-500-spec.pdf

USP - 500 - 48 type..

I will try and compare to a linear PSU .. Will of course post impressions.

Sincerely
 
#753
If you're going down the SMPS route you'll need two PSUs. This amp runs off +/- 40 V (up to 50 V is apparently OK) connect the negative output of PSU A to the positive output of PSU B. This gives you + and - 48 V as well as 0 V where the two PSUs are connected.

BUT: Make sure that the PSUs are bridgable. You may need to put some ultrafast diodes on each wire (before joining the two) otherwise you may end up with some unfortunate effects (instability, sparks, smoke, fire).

OR: get a SMPS that provides dual voltages.

It's probably cheaper and easier to use a linear PSU...
 
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