Not really a good or practical solution though as you'd need some way off measuring the resistance and ensuring value doesn't drift.
Is it possible to drive a subwoofer using this 2.0 amp in pbtl mode?
If so what should be the impedance of the subwoofer speaker.
If this doesn't suit for that can you experts suggest me a good ebay kit to drive a subwoofer?
Thanks!
If so what should be the impedance of the subwoofer speaker.
If this doesn't suit for that can you experts suggest me a good ebay kit to drive a subwoofer?
Thanks!
2 ohm for 100 Watt. If that is sufficient depends on the sensitivity of the drivers and your needs.
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Thanks for your reply 🙂
2ohm means I have to use two 4ohm speakers and parallel them to get 2ohms 🙁
I don't think that's a good choice.
Can you suggest me a amp kit to drive a 4 ohm speaker with 100W power?
I don't know, but if you know if it is going to run on a power supply or battery, somebody will probably be able to help you 🙂
The TI EVM board uses a tiny SMT 100k pot to set the gain. Drift is not an issue as the resistances only have to be roughly in range to set an analog voltage which goes to a comparator that then sets discrete gains inside the amp. It has nothing to so with accuracy of the resistors. You basically get a 5 discrete step gain knob controlled by an analog pot voltage divider.
I know. It's still not a practical solution for a finished product. The 5 resistor and 4:1 mux (like a ADG5204) is much more elegant as that only requires the setting of 2 dip switches. One determines slave or master status, the other determines the high or low gain setting.
I have 2 of the "YJ Blue" boards that I got in last week. My intention is to use them with a MINI DSP unit to prototype 2 way speaker crossovers. I would like to see a wiring diagram that would allow me to do as you suggest with the dip switches and syncronizing the amps clocks. I bought 2 power supplies, but would be much simpler to run only one supply.
I bought the boards because of the through hole components, I have little confidence I can re-work an SMD board....
I've really enjoyed following along on this thread since almost the beginning. The postings from folks like Saturnus have been very educational, thanks!
John
xrk971,
Thank you for pointing that out. I was thinking of using a step-attenuator (those 21 steps resistor ladder type) that clicks when you turn. So, all one needs to remember is how many clicks for each setting. Then mark it with a dial. Since the amount of current going through the potential divider is quite small (correct me if I am wrong), there will not be much heat generated. I was told that resistance drift is mostly due to thermal aging - so no concern there.
Actually, it might be interesting to try out different input impedance values (and gain) with different sources - just to see any impact on the sound.
Regards,
Well, I agree that it might not be an elegant solution for a finished commercial product. But for DIY purposes, it is convenient enough and should work fine. I have a few of those step-attenuators lying around if I decide to try it out. One can attach the potentiometer to the front panel and people might think it is just a volume pot. The advantage of setting it up this way is I can change the settings readily when I use different sources ( I am more interesting in the change of input impedance and gain than setting the amp to slave/master mode).
Regards,
Do you plan to run the board in stereo (BTL) or mono (PBTL) mode? If you plan to run the board in PBTL mode and sync the two chips (boards), you have to hard wire the two #16 legs, as shown in the schematic (figure 27) on p.14 of the data sheet. That's after you have set one of the amp to slave mode by implementing the gain/input impedance values that you want.
Regards,
I think that the adjustable gain trim pot with a knob on front panel can work for DIY purposes but if I am not mistaken it is not real time gain switching - I think it reads the voltage setting at power up and sticks with it until next power cycle. So you can change gain but it will require switching off and back on again. I have to read spec sheet again to confirm this though.
Also, what does master and slave syncing have to do with gain settings? I thought that is simply the oscillator clock of one being tied to the other. What does gain have to do with if? It sounds very overly complicated the way it has been described in he past several posts.
Also, what does master and slave syncing have to do with gain settings? I thought that is simply the oscillator clock of one being tied to the other. What does gain have to do with if? It sounds very overly complicated the way it has been described in he past several posts.
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I think you guys need some time with the datasheet. That would be of GREAT help to have a fit, easy to consult thread.
The gain of the TPA31xxD2 family is set by the voltage divider connected to the GAIN/SLV control pin. Master or
Slave mode is also controlled by the same pin. An internal ADC is used to detect the 8 input states. The first four
stages sets the GAIN in Master mode in gains of 20, 26, 32, 36 dB respectively, while the next four stages sets
the GAIN in Slave mode in gains of 20, 26, 32, 36 dB respectively. "The gain setting is latched during power-up
and cannot be changed while device is powered." Table 1 shows the recommended resistor values and the state
and gain:
The gain of the TPA31xxD2 family is set by the voltage divider connected to the GAIN/SLV control pin. Master or
Slave mode is also controlled by the same pin. An internal ADC is used to detect the 8 input states. The first four
stages sets the GAIN in Master mode in gains of 20, 26, 32, 36 dB respectively, while the next four stages sets
the GAIN in Slave mode in gains of 20, 26, 32, 36 dB respectively. "The gain setting is latched during power-up
and cannot be changed while device is powered." Table 1 shows the recommended resistor values and the state
and gain:
I think I'm going to buy that YJ Blue board soon but I have a question.
Will my laptop power supply adapter, HP 19v/7.1a unit work? I may have to solder on the proper end connector if needed. Thanks.
Will my laptop power supply adapter, HP 19v/7.1a unit work? I may have to solder on the proper end connector if needed. Thanks.
I am running the red board on a 19v laptop adapter and it's working perfectly. So i expect the same from the blue board.
Also, 7.1 A is a seriously big laptop adapter 😉
Verstuurd vanaf mijn LT22i met Tapatalk
Also, 7.1 A is a seriously big laptop adapter 😉
Verstuurd vanaf mijn LT22i met Tapatalk
Yup. That's exactly why I suggested the 3 or 5 fixed resistor set up for those that want to change the gain and/or master/slave setting.
I still maintain that even for a DIY product a variable resistor is an impractical solution as it requires people having to measure the resistance very carefully while setting it up and since we're talking about something very close to the chip potentially even under the heat sink and that would be hard for even experienced DIYers.
My comment on value drift using a pot is not related to heat generated in the pot itself but due to the fact that by necessity the pot would have to be next to or even under the heat sink, so it's transferred heat from that. Naturally using a multi-turn pot would all but eliminate that potential for error.
There's several ways a 2- or 4-way wiper can be implemented. A 4:1 mux is elegant but complicated but it could be done more simply by a single pole 4 position rotary or slide switch in miniature size, or even with jumpers.