New TK2050 board

[Don Jerry]

Originally Posted by SOSx

Another quick question. Does this board require a separate 5v dc power line also?

No. Separate 5v dc power is NOT required.
Bye!

[hifimediy]

Originally Posted by SOSx

Dear hifimedy,

A quick question? As I have stated I am using your boards for a mobile audio system.
I am looking at batteries for the system.

We would very much like to employ a 24v lifepo4 battery pack due to size and weight.

Most seem to have nominal full charge of 28v-30v which I know from your posts is fine (if not near optimium) but the problem i can see is that the voltage cut off levels are generally between 16&19v.

Also as DC offset is varied according to input voltage, so surely as the batteries voltage lowers with discharge the dc offset will increase?

Will the board still operate safely at 16-19v?

Your thoughts (or anyone else for that matter)

Kind regards

Hi, We use 24V relay on v2.0 board, so if below 18V, will lead to unstable for relay(may not able to turn on the relay). But for DC offset, I think it will be ok, will be almost stable(offset no more than 10mV in my test) when down to 16V. But I think the board will not be destroyed when 16V or even lower.

[hifimediy]

Originally Posted by Don Jerry

Another question for hifimediy:
using the same type of capacitors, what I should expect using 2.2uF caps intead of 3.3uF? I read the Tripath datasheet but honestly I didn't understand in which manner the uF value affects the audio signal.
Thanks, bye!!

Hi, refer to high pass filter formula.
fc=1/ (2*π*Ri*Ci ), π=3.14. Ri=20k
if you use Ci=2.2uF, fc=1/(2*3.14*20000*0.0000022=3.6Hz
means your amplifier will allow down to 3.6Hz siglal input.
we use Ci=3.3uF now, and will get better bass.
But don't try to use larger caps, which will lead to power off pop noise( will not happen on our boards, but we still not suggest use unnecessary large caps).
thanks.

[Don Jerry]

Originally Posted by hifimediy

Hi, refer to high pass filter formula.
fc=1/ (2*π*Ri*Ci ), π=3.14. Ri=20k
if you use Ci=2.2uF, fc=1/(2*3.14*20000*0.0000022=3.6Hz
means your amplifier will allow down to 3.6Hz siglal input.
we use Ci=3.3uF now, and will get better bass.

Into the 2-3Hz range there should be no audible audio signal.
However I think that you refer to the slope, so increasing or decreasing 1Hz in the high pass filter could affect the audible audio range.
I'm correct?

[SOSx]

Thank you for the replies.

So what voltage do think the relays would not open?
As long as the board is not damaged by the low voltage thats fine.

With the batteries i am looking at the Under voltage (discharge) protection should kick in at about 18-20v and turn the unit off anyway.

Kind Regards

[Don Jerry]

Originally Posted by SOSx

Thank you for the replies.

So what voltage do think the relays would not open?
As long as the board is not damaged by the low voltage thats fine.

With the batteries i am looking at the Under voltage (discharge) protection should kick in at about 18-20v and turn the unit off anyway.

The absolute minimum for the relays should be 17Vdc, so you should be just fine.

[hifimediy]

When you need to use a voltage bellow we suggest, the state of relays will be unsure.
I tried 16VDC on one of my board and find the relays can turn on, but I'm still not sure if other ones can, and not sure every time it will work. So we'd better make sure the voltage for relay will not be lower than 18V DC. We always give no less than 22V DC to make sure it will work.

[hifimediy]

Originally Posted by Don Jerry

Into the 2-3Hz range there should be no audible audio signal.
However I think that you refer to the slope, so increasing or decreasing 1Hz in the high pass filter could affect the audible audio range.
I'm correct?

Hi, we always don't want to cut any audio signal, so there is a reason to design the filter down to below 20Hz.

[vaughn]

Any issues with using this board with an active preamplifier? Kenwood C2 to be specific...

[alkasar]

very interesting board. I am tempted

Coming from gainclones, let me share a concern, maybe a bit off-topic, about smps.
Many people here seem to prefer smps.
Linear PSU (transformer + rectifier + caps) have large caps, to filter and also provide an energy tank to supply power instantaneously when needed. Frequently 50.000 µF or more for powerfull amps. This provides the amp "authority" to drive the speakers.
SMPS do not have this large tank. Neither do the amp boards here.

I just don't get how SMPS can compare to linear supplies with large caps ?


ps: great to see the board designer respond and take into account the users comments