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Class T Audio Amplifiers

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Hi
I have just built up an amp using the TA3020v3c, A1000SMPS and BIPS, it sounds great, but when powering down i get a sort of fizz from the speaker as the amp shuts down, any ideas as to what may be causing this? I have re-wired and checked everything and all is ok.

cheers Adrian
 
On the backside of the amplifier pcb, there is a diode, D17. this diode can be an usual switching diode such as 1N4148 for mains transformer powered amps or for smps can be replaced with a 39V Zenner diode connected with the cathode to the fuse connection and anode to R69. in this way, the amp will mute when the voltage will drop below 40V on supply rails and the noise will dissapear.
 
ta3020 v3c with IRFP4228 sounding great after diode tweak

I ordered a replacement for the TA3020 v3c some time ago to replace the one I wrecked trying to "improve" it, but on arrival it didn't work with my existing chassis/PSU.

Cristi offered to work with me on Skype and email to fix it at the time, though over the holidays I was to busy with other things (including updating drivers on my speakers, and travel) to put my full attention on it, until the last few days.

Interestingly replacing D17 on my board was the solution as well.. The older board has an "M7" SMD diode, while the newer replacement board had a different one (small glass SMD one with a higher measured voltage drop).
Replacing this with an 1N4004 as per Cristi's suggestion (after I emailed him voltages measured at various points on the board) and now the TA3020 v3c is up and running and sounding GREAT.

I have also updated my speakers (crossover & woofer) during this time so unfortunately I don't have a direct reference to A-B from, but the excellent sound I am expecting is there.

My speculation here is that maybe the speaker protection circuit diode is sensitive to the PSU voltage? I am using a 500VA toroidal transformer that supplies 40-0-40 to the board, this is about the highest it can go without needing a cooling fan.
 
Recomended PA system using your amps

Hi Cristi,
I am planning on building a small PA system using your amps.
1. My first order was a TA2022 amp (order #90). Which of your SMPS would you recommend (amp will be connected to an 8ohm HF compression driver rated at 50W)?
2. I would like to order two TA3020 amps (one powering the 450W 8ohm stereo mids and the other powering the 700W 4ohm sub at bridge mode). Would you recommend they share one SMPS or rather two separate ones?
3. Is there a problem housing all Amps in the same case?

Thanx
 
The suitable SMPS for TA2022 amplifier is SMPS180QR Connexelectronic if the amp will work on 4 R load, the SMPS250QR Connexelectronic can be considered.
2. i recommend to use separate smps for each amplifier if they are used for sub and mid. for the mid one, 450W the SMPS500R will do the job, and for the sub i recommend the SMPS800R. the TA3020v4 can be considered as well instead of smps+amp combination.
3. all the amps can be installed in the same case, just make sure they have at least few cm distance one from another and the signal wires will not be routed close to the power or output wires of the same or any other amplifier. try to keep a clean and short routing for wires, and avoid GND loops. also, the temperature inside the case must not exceed 50-55*C or the performances and reliability of the amps can be affected. having few amplifiers and smps in a single case must ensure a proper cooling, in most of the cases at least one fan is needed.
 
Cristi,

In regard to your new TA3020v4 combined power supply and amp module:

1. Do you see any problem relocating the cooling fan supplied with your kit from above the amp heatsink to the perimeter of the case, still nearby the heatsinks, but in a position where it is drawing air through the case in which the modules are installed, from outside of the case (or would a fan control component value need to be changed to increase the fan speed a little)?

2. Would you recommend using your TA3020v4 in BTL (bridge) mode for maximum fidelity sound, or does this depend on many factors such as speaker impeadance, power levels used for listening, frequency used through the particular module, etc. (I already know about the relative merits of bridged vs non-bridged mode for non class D/T amps, but are seeking your input with your specialised knowledge of your above amp and power supply module)?

Thanks for your input Cristi.
 
The actual position of the fan on the heatsink is the best position if the air intake can be assured on the top or front of the case, the air circuit must follow this path: power stage heatsink, then half evacuated thru the power supply heatsink and transformer before exits the case, the other half on the front side of the case. In the next version i plan to make some layout changes which will allow the board to have a lower profile, tush fitting in a 1RU case. i will consider other cooling options as well.

Running the TA3020v4 amplifier in BTL mode is justified when a higher output power is needed, higher than each channel can provide in SE mode. then for stereo, two modules are needed. another advantage of the BTL mode is that the pumping effect is eliminated, allowing a cleaner sound when high volume low freq. are played.
 
The TDA2500/TA0105A Reference Board Amplifier Module is based on the TDA2500/TA0105A digital audio power amplifier driver from Tripath Technology. This board is designed to provide a simple and straightforward environment for the evaluation of the Tripath stereo TDA2500/TA0105A amplifier. This board has 2 versions, one for low-impedance applications, such as 4 and 8 Ohms and can provide up to 500W with 0.1% THD on each channel, and is fitted with 200V Vds MOS-FET Transistors and higher impedance, such as 25-50 Ohms where can provide up to 400W with 0.1% THD on each channel and is fitted with 500V Vds MOS-FET Transistors. The acctual board is fitted with TA0105A driver which is the improoved version of the TDA2500 and STW34NB20 MOS-FET Transistor. On request, TDA2500 driver can be provided. Note that the TDA2500 and TA0105A are pin by pin compatile, the difference consist in their functionality and parameters.
 
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