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XRK RTR TPA3255 Reference class D Amp GB2

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xrk971

xrk971

Founder of XSA-Labs
Joined 2012
etsy.com/shop/XRKAudio
Paid Member
#1
Edit Dec 5. 2020: the GB is now taking preorders in my shop. I am including a free BTSB PCB with each order.

XRK RTR TPA3255 Reference class D Amp GB2

RTR TPA3255 Reference Class D amplifier | Etsy

This is the GB number 2 thread for the ready to run (RTR) TPA3255 reference Class D amp from this thread:
TPA3255 Reference Design Class D Amp GB

836851d1587609199-tpa3255-reference-design-class-amp-gb-67aa1113-6c7f-4ff0-91da-9f8655028f17-jpeg


The thread has a lot of details on the development process and build question and answers. A GB interest list will just get buried and lost in it so I decided to make a new thread as there seems to be some renewed interest now that Redjr has just released his masterpiece build using this amp. I have already received several requests for more RTR amps.

To make this viable for a manufactured amp from a California based assembly house, I will need a commitment for at least 20 amps from folks here. I will pledge to buy another dozen amps and we then get these professionally made using a pick and place machine with a genuine Mouser BOM.

As before, the default amp will be balanced input stereo BTL output. We now have the BTSB Buffer board to go with it which will provide the necessary conversion from SE inputs and gain to drive this amp effectively.

BTSB Buffer - SE/Bal to SE/Bal Buffer GB

The amp will be manufactured using 2mm thick pcb’s and 2oz copper and ENIG finish. Amp modules will be fully tested and come with a set of Molex connectors for audio in, speaker out, and PSU in. Pricing of the amp will be $277 each. The lead time may be up to 3 months, although I think it will go much faster this time since it is a second run and we have the kinks all worked out.

Edit Aug. 21, 2020: Special Promotion - Free BTSB Buffer PCB (TH or SMT) with your order of the RTR amp. A $23 value that allows this amp to be used with any source.

Please put your name, number of boards, and country down on the list below. Once we have 20, I will put a preorder listing on my shop for you to purchase.

Thanks,
X


Interest List:

Name / number of amps / country
____________________________

JohnDoe / 2 amps / USA
 
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#8
The way to prevent pop sound on power-up is a delayed release ob TPAreset-pin=low. For power-down an early TPAresetpin=low mutes the output before pops come in. This requires some extra circuitry like an power-on-reset-chip with delay or a microcontroller. Which is the way I do it.
Furthermore it is helpful to study TIs datasheet completely which tells you that increasing input coupling caps beyond sane values is another source of introducing pop noise.
 
#10
If anyone has doubts about the sound quality or performance of this amp, you might want to look at Redjr's review of his build here:
https://www.diyaudio.com/forums/class-d/87913-class-amp-photo-gallery-162.html#post6305030

The Sound --

I have to say that I have build a number of class D amps, and by far this is the best sounding DIY solution I have found. The first thing I immediately noticed was how quiet this amp is. There is nothing but silence when it's turned on. Then when the music starts.... wow! While class D amps may have a 'bright' overall sound, in my listening to it over the past several weeks, I never found this amp harsh, or fatiguing to listen to in any way. Instead, the sound is smooth, full-bodied yet very articulate in executing the music with clarity and detail. With plenty of wonderful and warm sounding mids, and solid bass when called upon.
Click to expand...

867116d1597094895-class-amp-photo-gallery-p1020239-jpg


867119d1597094994-class-amp-photo-gallery-p1020268-jpg


867117d1597094895-class-amp-photo-gallery-p1020300-jpg


Redjr has kindly provided the CAD files for making the same custom front and rear panels from Frontpanelexpress here:
TPA3255 Reference Design Class D Amp GB
 
#19
New measurements using the BTSB Buffer for SE to Balanced conversion with 20dB gain turned on. Beautiful result - the BTSB doesn’t add any noise or distortion. Basically at the limit of the Focusrite.

Here is the reference condition of 10Vrms into 10ohms (10w). At 0.0012% THD is similar to earlier measurement with THAT1646 but we now have up to 20dB of gain. Plus the HF hash is reduced.

attachment.php


The noise floor is so low (-130dB) you could use it as a headphone amp. 🙂

More info on the measurements here:
BTSB Buffer - SE/Bal to SE/Bal Buffer GB
 
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#20
Hi everyone, I'm Italian and I don't speak English, I use a translator, if I understand correctly you assemble TPA3255 homemade and then sell them? explain me better please I am very interested, for the moment I have a simple TPA3255 AIYIMA A07 that does not make pop noise and with a DC 48V 7.3A power supply and sounds great with Speakers (Focal Chorus 726).
 
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