• WANTED: Happy members who like to discuss audio and other topics related to our interest. Desire to learn and share knowledge of science required. There are many reviews of audio hardware and expert members to help answer your questions. Click here to have your audio equipment measured for free!

DIY Purifi Amp builds

MicroAudio

Active Member
Audio Company
Joined
Mar 27, 2020
Messages
143
Likes
208
Location
AMMAN - JORDAN
I also can hear noticeable “click” from speakers during power on cycle.
When S1 in EVAL1 is always on, clicking on power on cycle is audible. When I switch on S1 a while later manually then there is no click.
I also tested “amp enable” signal connected directly to SMPS. Clicking is also audible.
It looks like Purifi should be enabled a little bit later. I’m going to test that with additional relay with appropriate delay.


Good.

That's why I introduced the delayed output into all models I make.

It will enable the amplifier after the SMPS output voltage stabilized then enable the amplifier after 1 to 3 seconds can be adjusted.

And it turns OFF the amplifier immediately once you turn off the SMPS or put it into standby.

Also, there is another delayed output to control your DC protection circuit if you have one, so your speakers will never burn in case of amplifier failure.

Hope you solve it soon.
 

boXem

Major Contributor
Audio Company
Joined
Jun 19, 2019
Messages
2,014
Likes
4,852
Location
Europe
I switch it off duringThe test and amp enable signal enabled modules anyway. I performed similar test without S1 (I won’t use it in my project) and result is the same.

What interesting I also test the scenario where I connected amp enable signal manually (also through a relay) a few seconds after I turned on amplifier and clicking is also audible.
Do I understand correctly that the only case without click is by manually enabling with S1 after power is set?
 

tlag

Member
Joined
Jun 1, 2020
Messages
25
Likes
19
OR, not NOR. The question was whether the switch has the amplifier enabled before supply is ready.
Right; forgot the /AMPON inversion. So S1 enable wins.

But anyway, yeah, starting to think this is all about start-up supply imbalance. Steady-state DC likely not a factor. So longer turn-on delay would help.
 

Attachments

  • 1594332787342.png
    1594332787342.png
    13.6 KB · Views: 132

starfly

Senior Member
Forum Donor
Joined
Jun 6, 2019
Messages
353
Likes
288
Well, I tested each amp individually with the most basic wiring, and they both work! At least, the amp enable LED (which I had wired up as well) turned on for each amp.

So now on to figuring out all the other stuff for standby power, 12V trigger and standby push button switch in front. And most importantly, wiring up the input and output signals :D
 
OP
J

JimB

Addicted to Fun and Learning
Forum Donor
Joined
Sep 19, 2019
Messages
731
Likes
493
Location
California
R:-13.3mV
L:17.2mV
What is the maximum acceptable level?

I switch it off duringThe test and amp enable signal enabled modules anyway. I performed similar test without S1 (I won’t use it in my project) and result is the same.

What interesting I also test the scenario where I connected amp enable signal manually (also through a relay) a few seconds after I turned on amplifier and clicking is also audible.
I'd say that amount is good, and, per prior communication with Purifi, it is within spec:
https://www.audiosciencereview.com/...y-purifi-amp-builds.10478/page-25#post-336085

Is that the cause of what you hear at turn on? Try Disconnecting and reconnecting the speaker leads while the amp is on, but not playing anything. What do you hear as you make and break contact?
 

TimoJ

Senior Member
Joined
Dec 9, 2019
Messages
412
Likes
448
Location
Finland
What interesting I also test the scenario where I connected amp enable signal manually (also through a relay) a few seconds after I turned on amplifier and clicking is also audible.
How are you going to wire the delay relay? To the pins where S1 is/was connected? I also have this turn-on click, S1 is removed, AmpOn is connected and I have wired a front panel "power" switch that also uses it to disable/enable the amp. I use an external relay box to switch the AC power on/off and the front panel switch is just for occasional use. Front panel switch AmpOn toggle seems cause clicks (both on and off) but I think the startup click after AC is connected is a little louder.

I never tested how S1 works. So there is something different in the way S1 works vs. AmpOn and it avoids the click with S1? I'm wondering could the circuit be changed so that AmpOn would work without clicks? Has Purifi released schematics of the S1/AmpOn circuit?
 

boXem

Major Contributor
Audio Company
Joined
Jun 19, 2019
Messages
2,014
Likes
4,852
Location
Europe
I never tested how S1 works. So there is something different in the way S1 works vs. AmpOn and it avoids the click with S1? I'm wondering could the circuit be changed so that AmpOn would work without clicks? Has Purifi released schematics of the S1/AmpOn circuit?
My multimeter told me the other day that S1 was shorting /nAMPON to the board ground.
BTW, I just tried, S1 is causing slight clicks in my setup too.
 
D

Deleted member 65

Guest
Oooh my god! that is a killer one! Beautiful!!! Thanks for the sharing :D
And it amazes me again how precise and powerful the cords sound. I'm in love

Saw her live in Stockholm just prior corona, she rocks! Lookup her Youtube performance of Roxanne, you’ll be floored ...
 
  • Like
Reactions: Luc

tlag

Member
Joined
Jun 1, 2020
Messages
25
Likes
19
BTW, I just tried, S1 is causing slight clicks in my setup too.
FWIW, for me, same with /AMPON, regardless of S1 position. Speaker click comes shortly after relay click.

/AMPON always connected to SMPS1200. S1 sitting high at power up-->click. S1 sitting low at power up-->click.

But only just noticeable, better than most other amps I've had.

For context, my sub amp is a pro beast that causes not clicks, but big *thumps*, on turn-on/-off. A feature. :)
 
D

Deleted member 65

Guest
Soon to start my Purifi build based on Neurochrome buffers, waiting for delivery of the voltage regulators from Neurochrome. Anyone knows whether it’s possible to retrieve temperature from the amps? Seems to be avaiable in the I2C reg map (0x11)?
 

Luc

Member
Joined
Jul 7, 2020
Messages
18
Likes
19
Do I understand correctly that the only case without click is by manually enabling with S1 after power is set?

no, the delay function should eliminate the click (that is anyway very low with purifi/micro-audio smps)
i'll tell once i've wired it
 

TimoJ

Senior Member
Joined
Dec 9, 2019
Messages
412
Likes
448
Location
Finland
no, the delay function should eliminate the click (that is anyway very low with purifi/micro-audio smps)
i'll tell once i've wired it
Delay where? If you manually operate AmpOn and the amp still clicks, how can adding delay help? I think only fix is to install speaker relays (probably a bad idea) or modify Purifi's AmpOn circuit
 

Luc

Member
Joined
Jul 7, 2020
Messages
18
Likes
19
Delay where? If you manually operate AmpOn and the amp still clicks, how can adding delay help? I think only fix is to install speaker relays (probably a bad idea) or modify Purifi's AmpOn circuit

SMPS delay
with that function, the result should be like manually turning S1 "on" after SMPS's ready
 

kukocz

Active Member
Forum Donor
Joined
Nov 19, 2018
Messages
166
Likes
155
Location
PL
Electrically, that's totally fine. Practically, depends on speaker/listener sensitivity, listening distance, and personal subjective threshold. With, say, 86dB/Wm speakers at 3ft, I would've thought it barely audible and not a big deal. But total guess; YMMV.

Edit: Just thought of something. Did you measure DC with input open or connected to upstream component? In the end, what matters is with it all hooked up.
The data I provided was for open circuit. What interesting I swapped out the purifi modules and DC voltage decreased to:
R:-10.7mV
L:14.6mV

With connected source it measures:
R:-1.0mV
L:-0.8mV

So definitely it shouldn’t be a problem. My speakers are Tannoys XT8f with 91dB sensitivity.

Good.

That's why I introduced the delayed output into all models I make.

It will enable the amplifier after the SMPS output voltage stabilized then enable the amplifier after 1 to 3 seconds can be adjusted.

And it turns OFF the amplifier immediately once you turn off the SMPS or put it into standby.

Also, there is another delayed output to control your DC protection circuit if you have one, so your speakers will never burn in case of amplifier failure.

Hope you solve it soon.

SMPS1200A400 has built in soft start therefore, in theory, additional delay of “amp enable” line shouldn’t be necessary.

Do I understand correctly that the only case without click is by manually enabling with S1 after power is set?
Yes, correct. But now I’m confused if this is 100% for sure.
Test with S1 was done during the day. Test with manual enabling via “amp enable” was performed during late evening where ambience noise levels are usually lower and hearing perception more sensitive. This could influence my verdict although I put my ears really close to speakers in both cases.
Test with additional really in the “amp enable” path revealed similar clicks.

I'd say that amount is good, and, per prior communication with Purifi, it is within spec:
https://www.audiosciencereview.com/...y-purifi-amp-builds.10478/page-25#post-336085

Is that the cause of what you hear at turn on? Try Disconnecting and reconnecting the speaker leads while the amp is on, but not playing anything. What do you hear as you make and break contact?

Good point. I did that test and then click is almost inaudible. I said almost because then its level is comparable to the little his audible from the tweeter. :)

How are you going to wire the delay relay? To the pins where S1 is/was connected? I also have this turn-on click, S1 is removed, AmpOn is connected and I have wired a front panel "power" switch that also uses it to disable/enable the amp. I use an external relay box to switch the AC power on/off and the front panel switch is just for occasional use. Front panel switch AmpOn toggle seems cause clicks (both on and off) but I think the startup click after AC is connected is a little louder.

I never tested how S1 works. So there is something different in the way S1 works vs. AmpOn and it avoids the click with S1? I'm wondering could the circuit be changed so that AmpOn would work without clicks? Has Purifi released schematics of the S1/AmpOn circuit?

Amp enable and S1 is the same. It pulls down the “amp enable” signal to the ground.
“amp enable” doesn’t really decrease power consumption (it’s decreasing from ~24W to ~20W). In my opinion it should be treated rather as “mute” function not stand by.
Even SMPS in stand by takes ~10W what nowadays is not impressing in terms of power saving :)

Initially I planned to use a relay with built in delay function but as it didn’t work as expected (quiet click is still audible) I abandoned this idea.
My goal is to use bistable relay with momentary switch on front panel to cut the AC power for SMPS.
Only small 5V AC/DC module taken from usb phone charger will be powered in stand by mode.

My multimeter told me the other day that S1 was shorting /nAMPON to the board ground.
BTW, I just tried, S1 is causing slight clicks in my setup too.

Indeed.
What is interesting, when you touch with your fingers the “amp enable” wire, clicks and crack noises are audible from the speakers. Maybe S1 has the advantage over the long wire because the path is short B and not exposed to external interference... Maybe this is why S1 is quieter...?

FWIW, for me, same with /AMPON, regardless of S1 position. Speaker click comes shortly after relay click.

/AMPON always connected to SMPS1200. S1 sitting high at power up-->click. S1 sitting low at power up-->click.

But only just noticeable, better than most other amps I've had.

For context, my sub amp is a pro beast that causes not clicks, but big *thumps*, on turn-on/-off. A feature. :)

My NAD C356 has relays before speaker terminals so I’m not used to hear any clicks... :)
But you’re right. It’s so quiet and rather safe so we shouldn’t take it as a risk.

Delay where? If you manually operate AmpOn and the amp still clicks, how can adding delay help? I think only fix is to install speaker relays (probably a bad idea) or modify Purifi's AmpOn circuit

You’re right. I thought it’s related to the fact that amp section is enabled too early. It turned out it’s not the case :)

SMPS delay
with that function, the result should be like manually turning S1 "on" after SMPS's ready

I still think that S1 is a little bit quieter than amp enable but I already get rid of S1 and cannot re-run the test.
I’ll have to live with that click :)
Especially, that in my opinion this can be forgiven in DIY project more than in commercial implementations for more $$.
 

MicroAudio

Active Member
Audio Company
Joined
Mar 27, 2020
Messages
143
Likes
208
Location
AMMAN - JORDAN
@
kukocz

"SMPS1200A400 has built in soft start therefore, in theory, additional delay of “amp enable” line shouldn’t be necessary. "

I never mentioned the soft start, and what I said has nothing to do with it either.

The delay output is something different and does not exist in HYPEX SMPS, HYPEX has AMP-ENABLE, I have AMP-ENABLE & Delay-Out (SMPS1K_PFC). also, hypex doesn't have a power factor corrector.

Delay output is an output that will be activated AFTER full stabilize of the power supply rails, and will immediately trip once disconnecting the SMPS or putting it into stand by.

Hope it's clear now.
 

phoenixdogfan

Major Contributor
Forum Donor
Joined
Nov 6, 2018
Messages
3,294
Likes
5,068
Location
Nashville
The data I provided was for open circuit. What interesting I swapped out the purifi modules and DC voltage decreased to:
R:-10.7mV
L:14.6mV

With connected source it measures:
R:-1.0mV
L:-0.8mV

So definitely it shouldn’t be a problem. My speakers are Tannoys XT8f with 91dB sensitivity.



SMPS1200A400 has built in soft start therefore, in theory, additional delay of “amp enable” line shouldn’t be necessary.


Yes, correct. But now I’m confused if this is 100% for sure.
Test with S1 was done during the day. Test with manual enabling via “amp enable” was performed during late evening where ambience noise levels are usually lower and hearing perception more sensitive. This could influence my verdict although I put my ears really close to speakers in both cases.
Test with additional really in the “amp enable” path revealed similar clicks.



Good point. I did that test and then click is almost inaudible. I said almost because then its level is comparable to the little his audible from the tweeter. :)



Amp enable and S1 is the same. It pulls down the “amp enable” signal to the ground.
“amp enable” doesn’t really decrease power consumption (it’s decreasing from ~24W to ~20W). In my opinion it should be treated rather as “mute” function not stand by.
Even SMPS in stand by takes ~10W what nowadays is not impressing in terms of power saving :)

Initially I planned to use a relay with built in delay function but as it didn’t work as expected (quiet click is still audible) I abandoned this idea.
My goal is to use bistable relay with momentary switch on front panel to cut the AC power for SMPS.
Only small 5V AC/DC module taken from usb phone charger will be powered in stand by mode.



Indeed.
What is interesting, when you touch with your fingers the “amp enable” wire, clicks and crack noises are audible from the speakers. Maybe S1 has the advantage over the long wire because the path is short B and not exposed to external interference... Maybe this is why S1 is quieter...?



My NAD C356 has relays before speaker terminals so I’m not used to hear any clicks... :)
But you’re right. It’s so quiet and rather safe so we shouldn’t take it as a risk.



You’re right. I thought it’s related to the fact that amp section is enabled too early. It turned out it’s not the case :)



I still think that S1 is a little bit quieter than amp enable but I already get rid of S1 and cannot re-run the test.
I’ll have to live with that click :)
Especially, that in my opinion this can be forgiven in DIY project more than in commercial implementations for more $$.
Just how loud is the click? Loud enough to damage your speakers? To startle? To my mind a soft click does not harm at all. I am still awaiting my final drilled case to assemble my Eval1, but I'm not losing any sleep whatsoever over a minor click upon turn on. If it's more than minor I'd of course like to know, but otherwise...well, I guess I'm just not as perfectionisic as others on this thread.
 

MicroAudio

Active Member
Audio Company
Joined
Mar 27, 2020
Messages
143
Likes
208
Location
AMMAN - JORDAN
Just how loud is the click? Loud enough to damage your speakers? To startle? To my mind a soft click does not harm at all. I am still awaiting my final drilled case to assemble my Eval1, but I'm not losing any sleep whatsoever over a minor click upon turn on. If it's more than minor I'd of course like to know, but otherwise...well, I guess I'm just not as perfectionisic as others on this thread.

I am sure it's just a low-level click, and it is related to the amplifier itself, and it's normal.

I can hear that with ICE power modules usually, and dbtechnologies, RCF
 
Top Bottom