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Amplifier Modules and PCBs For Sale

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Deleted member 148505

ricyuyc said:
no PFFB on TPA3251 because there is no significant improvement on output?
Click to expand...

We can't remove the pop/tick on TPA3251 modules. It is even present on voltage supervisor enable/disable event.

For your module, we will check if a 3.3uF input coupling cap will solve the issue.

If it solves the issue, then we will provide PFFB for Sylph-D200.

454Casull said:
Dang it. Hopefully the measurements of the TPA3255 @ 48 V are good enough because I definitely do not want to get another power supply.
Click to expand...

It is only for March 5 release. If we streamline the manufacturing of different configurations, we will offer PFFB @48V. (using different PFFB values require more setup for manufacturing which increases cost)
 
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Deleted member 148505

I created a follow up soundcard interface using isolated 5V to +/-15V, TPS7A49/30, OPA1656 and INA1651. This module won't be a bottleneck for MOTU M4.

SMT parts assembled by JLCPCB (attached bottom pcb pic).
 

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jimk04

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Joined 2018
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Thanks Lester for the update and for the fantastic support to your customers.

I'm just tweaking my psu. At present I have 500va trafo >Lt4320 ideal rectifier>30800uf cap bank .
I measure 6mv AC ripple at idle but peaks 60 to 100mv on transients when the volume is way up...uncomfortable levels.
So I am trying a capacitance multiplier and see what that brings.
It will drop my psu 2 to 4 v but will still be about 44 to 46V so I shall stick with non PFFB.
Thanks for all your work on these great amps
 
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Deleted member 148505

jimk04 said:
How do you find SQ difference between 3255 @ 36v compared with non PFFB @48v?
Click to expand...

I already tried comparing the two since I have an adjustable supply here. Can't tell the difference with 48V using non-PFFB module, maybe I need more listening time or maybe we are using heavy duty inductors that's why using higher voltage has negligible effect.

You can use a variac since you are using a linear supply.

I prefer non-PFFB since it sounds more balanced and natural, With Sylph-D200, PFFB sound is more airy but the voice is more prominent since lower midrange is attenuated (by ear).

I also bought a new bookshelf speaker today to check PFFB vs non-PFFB sound in a different speaker setup.
 
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Deleted member 148505

My new speaker has arrived.

I compared PFFB vs non-PFFB, on this speaker, PFFB has an attenuated "lower midrange" around 200hz to 500hz, clarity is also better. Non PFFB has normal sound. If I equalize and increase 200hz to 500hz then non-PFFB and PFFB sound more or less the same.
 

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Mello4

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Joined 2021
JLesterP said:
We can't remove the pop/tick on TPA3251 modules. It is even present on voltage supervisor enable/disable event.....
Click to expand...

My Aiyima 04 with TPA3251 has NO pop during start up or turn shutdown. Normally a pop is due to DC offset voltage charging or discharging a capacitor in the signal chain.

It takes about 7 seconds before I hear sound, after I turn on the power to the amp (using always on wall wort brick). Maybe on the Aiyima 04 TPA3251 design they are delaying one of the power Vdd lines?

On the TPA3251EVM board there is a TPS3802 time delay reset IC with a 400mS delay tied to the reset pin.
 
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Deleted member 148505

Mello4 said:
My Aiyima 04 with TPA3251 has NO pop during start up or turn shutdown. Normally a pop is due to DC offset voltage charging or discharging a capacitor in the signal chain.

It takes about 7 seconds before I hear sound, after I turn on the power to the amp (using always on wall wort brick). Maybe on the Aiyima 04 TPA3251 design they are delaying one of the power Vdd lines?

On the TPA3251EVM board there is a TPS3802 time delay reset IC with a 400mS delay tied to the reset pin.
Click to expand...

Yes we are also using supervisor IC 1100mS delay, the tick is present at the mute-unmute of the TPA3251 and we can replicate it by shorting out the mute pin when the amp is running normally (out of startup/shutdown sequence).

Using smaller value coupling capacitor or disabling PFFB fixes the problem. PFFB contributes to the pop/tick since 1/2 PVDD is being fed back to the summing junction.

Vunce said:
Hi JLesterP,

Is the heatsink on the Sylph-D200 adequate running a 48vdc psu into 8R load?
Click to expand...

Yes it's more than adequate :)
 
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Deleted member 148505

Vunce said:
The reason for my concern is because I was using a 100mm x 40mm x 25mm heatsink on my TPA3255 (Sylph-D200 sink looks smaller) and it was not adequate. The HS would be 60°C at moderate listening volume. I worried about long term reliability, especially if I wanted to pump up the volume.
Click to expand...

Sylph-D200 is using the same heatsink as the TI's EVM (ATS-TI1OP-519-C1-R3). Granted that TI engineers only designed the EVM for 1/8th of full power which is around 75W of continuous output.

Top heatsink attachment also makes modification of parts easy. It's very difficult to disassemble a bottom mounted heatsink.
 
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