• WANTED: Happy members who like to discuss audio and other topics related to our interest. Desire to learn and share knowledge of science required as is 20 years of participation in forums (not all true). Come here to have fun, be ready to be teased and not take online life too seriously. We now measure and review equipment for free! Click here for details.

DIY Purifi Amp builds

OP
J

JimB

Addicted to Fun and Learning
Forum Donor
Joined
Sep 19, 2019
Messages
712
Likes
452
Location
California
Thread Starter #1,301
... so I wouldn't be able to mount the base panel flush with the front panel. ...
Need good, uniform contact between the front panel and the SMPS? Not going to be easy with flat heads. Use slightly oversized, or short slotted holes, not countersunk, and pan head screws. Slide the SMPS against the panel and snug down those screws..
 

tlag

Member
Joined
Jun 1, 2020
Messages
24
Likes
19
Need good, uniform contact between the front panel and the SMPS? Not going to be easy with flat heads. Use slightly oversized, or short slotted holes, not countersunk, and pan head screws. Slide the SMPS against the panel and snug down those screws..
Actually quite difficult, if not impossible, to achieve truly good front plate surface contact using bottom screws alone. For me, at least. Too many variables, hence mine's "casual" contact. Far more secure to drill front panel and replace SMPS screws. Or at least use thermal pads, like Bergquist or somesuch.
 
OP
J

JimB

Addicted to Fun and Learning
Forum Donor
Joined
Sep 19, 2019
Messages
712
Likes
452
Location
California
Thread Starter #1,304
Actually quite difficult, if not impossible, to achieve truly good front plate surface contact using bottom screws alone. For me, at least. Too many variables, hence mine's "casual" contact. Far more secure to drill front panel and replace SMPS screws. Or at least use thermal pads, like Bergquist or somesuch.
Short of bolting through the front panel and the bottom, I'm satisfied with the method of good ventilation there, like we see in a typical Ghent case for Hypex modules:
1594000177052.png


1594000409056.png
 

starfly

Active Member
Forum Donor
Joined
Jun 6, 2019
Messages
187
Likes
169
So I need some advice regarding correctly and properly wiring up the electrical parts of the system, specifically correctly and safely grounding both electrical and signal.

From my reading so far, I should connect the ground wire from the IEC socket to bare metal on the chassis. And on the XLR socket, the ground (Pin 1 I believe) should also make direct contact with bare metal on the chassis and I shouldn't bother connecting Pin 1 to the input buffer. But I see that for example the SMPS power supply also has a screw next to the socket for the A/C wires to which I could connect a ground wire (I saw at least one build on here that did so).

I have so far also been shaving off the anodization where I've drilled holes for attaching components to the base plate, so that the screws make direct contact with bare metal (and thus probably also provide some form of grounding for every component).

Are all my assumptions correct so far? Am I missing anything?
 

barrows

Active Member
Joined
Jan 24, 2020
Messages
131
Likes
167
So I need some advice regarding correctly and properly wiring up the electrical parts of the system, specifically correctly and safely grounding both electrical and signal.

From my reading so far, I should connect the ground wire from the IEC socket to bare metal on the chassis. And on the XLR socket, the ground (Pin 1 I believe) should also make direct contact with bare metal on the chassis and I shouldn't bother connecting Pin 1 to the input buffer. But I see that for example the SMPS power supply also has a screw next to the socket for the A/C wires to which I could connect a ground wire (I saw at least one build on here that did so).

I have so far also been shaving off the anodization where I've drilled holes for attaching components to the base plate, so that the screws make direct contact with bare metal (and thus probably also provide some form of grounding for every component).

Are all my assumptions correct so far? Am I missing anything?
I have built a Purifi amp, and did it this way in order to achieve both safety and the lowest noise:

1. Always connect a short, large gauge wire directly from the IEC input connector to the chassis, remove anodization at the mounting point.
2. If using the SMPS 1200, its bottom plate is grounded, so I recommend removing some anodization from the chassis at one corner hole where the SMPS 1200 screws in-this only needs to be done at a single corner (in fact, it is probably better to do it at just one corner). I would test for ground continuity from the SMPS heatsink to chassis and IEC ground pin after the SMPS and IEC remounted and the ground connection is made.
3. Best practice, is to connect the XLR jack pin 1 directly to chassis, with as a short a wire as possible. I use 18 AWG here, with ring terminal on one end, and secure it to one of the screws holding the XLR jack in place, again, remove anodization around the XLR mounting hole (and on the XLR jack if using ones that are painted, like Neutrik black ones).
4. The eval board ground (output) needs to be connected to ground as well, it can go to chassis, I connected each one to the other XLR mounting screw (not the same one which has the pin one connection).

BTW, the above connection scheme was what Bruno Putzeys recommended back in the days of the introduction of the NC-400s.
 

starfly

Active Member
Forum Donor
Joined
Jun 6, 2019
Messages
187
Likes
169
I have built a Purifi amp, and did it this way in order to achieve both safety and the lowest noise:

1. Always connect a short, large gauge wire directly from the IEC input connector to the chassis, remove anodization at the mounting point.
2. If using the SMPS 1200, its bottom plate is grounded, so I recommend removing some anodization from the chassis at one corner hole where the SMPS 1200 screws in-this only needs to be done at a single corner (in fact, it is probably better to do it at just one corner). I would test for ground continuity from the SMPS heatsink to chassis and IEC ground pin after the SMPS and IEC remounted and the ground connection is made.
3. Best practice, is to connect the XLR jack pin 1 directly to chassis, with as a short a wire as possible. I use 18 AWG here, with ring terminal on one end, and secure it to one of the screws holding the XLR jack in place, again, remove anodization around the XLR mounting hole (and on the XLR jack if using ones that are painted, like Neutrik black ones).
4. The eval board ground (output) needs to be connected to ground as well, it can go to chassis, I connected each one to the other XLR mounting screw (not the same one which has the pin one connection).

BTW, the above connection scheme was what Bruno Putzeys recommended back in the days of the introduction of the NC-400s.
So, wire the IEC like this?

20200706_211221.jpg

As for the SMPS1200, I had already filed off the anodizing at all 6 screw holes. What's the risk of that vs just having one hole with bare metal?

And what's the best way to test for ground continuity? Use an ohm meter?
 

kukocz

Active Member
Forum Donor
Joined
Nov 19, 2018
Messages
140
Likes
127
Location
PL
Hi all, I just finished the 7 channel power amplifier. Thanks for all of them in thread because I acquire a lot of very useful information :)
Nice project.
This module with two orange relays is standby or soft-start module?
 

barrows

Active Member
Joined
Jan 24, 2020
Messages
131
Likes
167
So, wire the IEC like this?

View attachment 72229

As for the SMPS1200, I had already filed off the anodizing at all 6 screw holes. What's the risk of that vs just having one hole with bare metal?

And what's the best way to test for ground continuity? Use an ohm meter?
Yes, that looks fine. The sMPS 600 used in the NC-400 amps had a single metal standoff in order to ground the power supply at only one point, apparently this was to reduce RF emissions. As the entire bottom plate of the SMPS 1200 is at ground, perhaps this is not as important with this supply. In nay case, yours will be well grounded to the chassis with your approach and you should be fine.
Yes, check continuity with an ohm meter/DMM.
 

Luc

Member
Joined
Jul 7, 2020
Messages
18
Likes
19
Hi All,
For the very first time in the known universe :cool:, Purifi amp powered by Micro-Audio SMPS with PFC function!
So many thanks to Sami for the help and for allowing me that world first :D I'm so glad with that build.
Now checking everything and finalizing layout, details. And then soon to play music!
 

Attachments

Luc

Member
Joined
Jul 7, 2020
Messages
18
Likes
19
specifically designed with the Purifi in mind, pfc, many optional outputs, keeps very cool... and i did not want hypex :facepalm: :D
 

Similar threads

Top Bottom