Hi Folks,
We are really close to being able to start this second GB production run. I do have some good technical news. I finally tested out the master/slave frequency sync feature designed to prevent beat-note noise when two amps are being driven together in the same box and psu. I bought pre-crimped leads for the tiny connectors and set one as master and other as slave using the DIP switches. It all works as expected. So, if you are looking to use this AN’s multi amp in an active setup (perhaps for LX521 etc) it can work very well.
You can see the black twisted pair cable between the two amps.
We are really close to being able to start this second GB production run. I do have some good technical news. I finally tested out the master/slave frequency sync feature designed to prevent beat-note noise when two amps are being driven together in the same box and psu. I bought pre-crimped leads for the tiny connectors and set one as master and other as slave using the DIP switches. It all works as expected. So, if you are looking to use this AN’s multi amp in an active setup (perhaps for LX521 etc) it can work very well.
You can see the black twisted pair cable between the two amps.
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Thanks Max!
We had one more person back out, but I think to kick this off with a booster shot, I’ll buy the rest for us to reach 30.
GB status update:
30 amps total - ready to collect funds for production!
Thanks folks!
Preorder Listing in my shop. Please place your order and add note with your DIYA screen name so that I can track it.
Note that I am including a free BTSB balanced drive preamp PCB with this GB. Please choose TH or SMT. Note that these BTSB boards do not have SE output. But you don’t need that for driving the TPA3255.
RTR TPA3255 Reference Class D amplifier | Etsy
We had one more person back out, but I think to kick this off with a booster shot, I’ll buy the rest for us to reach 30.
GB status update:
30 amps total - ready to collect funds for production!
Thanks folks!
Preorder Listing in my shop. Please place your order and add note with your DIYA screen name so that I can track it.
Note that I am including a free BTSB balanced drive preamp PCB with this GB. Please choose TH or SMT. Note that these BTSB boards do not have SE output. But you don’t need that for driving the TPA3255.
RTR TPA3255 Reference Class D amplifier | Etsy
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GB status update.
I think the last one is for ahtllc, as it is for 2 boards and in USA.
I think the last one is for ahtllc, as it is for 2 boards and in USA.
Vunce / 1 Amp / USA
xrk971 / *14 Amps* / USA *Committed to ordering 14*
StarDollar / 1 AMP / Norway *Pre-Order Placed*
diy40 / 1 Amp / USA *Pre-Order Placed*
telliottaus / 2 Amps / Australia *Pre-Order Placed*
mb (mervin) / 1 Amp / Singapore
ahtllc / 2 amps / USA *Pre-Order Placed*
mahtew / 2 Amp / Poland *Pre-Order Placed*
CBRworm / 1 Amp / USA
chermann/2 amps/ Austria *Pre-Order Placed*
s610adam/ 1 amp / USA *Pre-Order Placed*
Bologna1 / 1 amp / USA *Pre-Order Placed*
Maxreboband / 1 amp / USA *Pre-Order Placed*
I am double checking the production BOM data. I am upgrading the PFFB resistors to Susumu 0.1% 25ppm metal thin film for the 33k and 2k7 values. This will ensure that the distortion in the feedback path is low and that the gain is accurate and doesn't drift. The default resistors in this amp are 1% metal thin film.
The parts in the BOM are all in stock at Mouser. I just found that I am short of 5 PCBs so need to order another batch.
The parts in the BOM are all in stock at Mouser. I just found that I am short of 5 PCBs so need to order another batch.
If you wanted to try this yourself as a DIY option, the way the power supply is laid out, there is a solder bridge that connects the various power supply stages from one another. This was made to allow each system to be isolated to test and debug PSU systems.
So the main 53v supply feeds a DCDC buck converter to 15v. There is a solder bridge there. Between the 15v and 12v linear regulator is another solder bridge. Between the 12v regulator to the 3.3v regulator is another solder bridge. In theory, you could remove the solder bridges that connect the 15v to 12v regulator and use your own external low noise 15v supply. There is a 3pin SOT223 12v regulator on board that could be replaced with one of your choice. Or you could simple bypass the onboard 12v regulator (remove it) and jumper two pins and rely on your external LT3045.
Note that as designed, the TPA3255 is one of the quietest amps I have ever tested with a noise floor already at the limit of my equipment (-135dB). I am not sure if using a better regulator is going to yield audible improvements.
I think I know where this is going as someone on another thread is using this regulator to provide an ultra low noise GVdd/Vdd for the TPA3255. Keep in mind that the TPA3255 is a Class D amp with tens of amps of current on board switching at 400kHz to 500kHz for the main audio load. The amp has noise in the 40uV level as designed, will the use of a 0.8uV noise LDO on GVdd/Vdd pins improve performance? I don’t know but I am quite sure -135dB and less is probably impossible to hear the difference.
But for the purposes of this GB2, I cannot change any layout or topology but only components. You can disengage the built in on board PSUs and connect your own external one at the solder bridges (marked Wxxx).
So the main 53v supply feeds a DCDC buck converter to 15v. There is a solder bridge there. Between the 15v and 12v linear regulator is another solder bridge. Between the 12v regulator to the 3.3v regulator is another solder bridge. In theory, you could remove the solder bridges that connect the 15v to 12v regulator and use your own external low noise 15v supply. There is a 3pin SOT223 12v regulator on board that could be replaced with one of your choice. Or you could simple bypass the onboard 12v regulator (remove it) and jumper two pins and rely on your external LT3045.
Note that as designed, the TPA3255 is one of the quietest amps I have ever tested with a noise floor already at the limit of my equipment (-135dB). I am not sure if using a better regulator is going to yield audible improvements.
I think I know where this is going as someone on another thread is using this regulator to provide an ultra low noise GVdd/Vdd for the TPA3255. Keep in mind that the TPA3255 is a Class D amp with tens of amps of current on board switching at 400kHz to 500kHz for the main audio load. The amp has noise in the 40uV level as designed, will the use of a 0.8uV noise LDO on GVdd/Vdd pins improve performance? I don’t know but I am quite sure -135dB and less is probably impossible to hear the difference.
But for the purposes of this GB2, I cannot change any layout or topology but only components. You can disengage the built in on board PSUs and connect your own external one at the solder bridges (marked Wxxx).
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