Douk Audio TPA3255 Amplifier with HPF is Coming! Let's Shape it Together!

[Krampi]

@Douk Audiio
Has the a5 been such a success that it is completely sold out? It even disappeared from my shopping cart on aliexpress.
it's spooky! after a few hours It's back in the cart!

 

[Audionaut]

It even disappeared from my shopping cart on aliexpress

 

[NovakJi]

Is it possible to buy this, plug it to my speakers (does not need anything else, right?) and somehow add Bluetooth connectivity to it, so I can use Spotify, etc. with it? Or there is not such possibility? Thanks a lot for help.

 

[Audionaut]

Is it possible to buy this, plug it to my speakers (does not need anything else, right?) and somehow add Bluetooth connectivity to it

Yes, sure. FiiO BTA30 Pro for example.
Or, much cheaper, something like this >>>

2-in-1 Bluetooth 5.2 Transmitter Receiver AptX Low Latency

【No Lip Sync Delay】Soomfon Bluetooth transmitter receiver delivers crystal-clear audio and let you watch tv without delay. It supports AAC, SBC, APTX, APTX-LL, APTX-HD and A2DP. NOTE: To achieve low latency ( <40ms delay), your receiving device must also support AptX Low Latency, or you may...

soomfon.com

 

[EJ3]

Yes, sure. FiiO BTA30 Pro for example.
Or, much cheaper, something like this >>>

2-in-1 Bluetooth 5.2 Transmitter Receiver AptX Low Latency

【No Lip Sync Delay】Soomfon Bluetooth transmitter receiver delivers crystal-clear audio and let you watch tv without delay. It supports AAC, SBC, APTX, APTX-LL, APTX-HD and A2DP. NOTE: To achieve low latency ( <40ms delay), your receiving device must also support AptX Low Latency, or you may...

soomfon.com

Note: (& it tells you but the print is fine): That it must be used with a Bluetooth receiver of equal codec reception capabilities.

 

[Douk Audio]

Hello all friends, thank you for your attention to our A5 amplifier and sorry for my late response since we just got back to work from our Spring Festival Holiday yesterday.
If you have any ideas or suggestions, please feel free to share them here. We will organize and feedback them to our development team to determine whether they are feasible. Thank you again!

 

[Guddu]

@Douk Audio
It seems to be that Douk Audio A5 is using an analog filter which typically has linear roll off, can you help in showing how the frequency roll off looks like on speaker output when HPF is enabled.
Example, I was testing something similar: analog filter with linear roll off.
Setting 200Hz HPF resulted in roll off starting around 600-700Hz, something like this:

Is it how Douk Audio A5 expected to behave as well?

 

[Batmobil3250]

The A5 would benefit from being able to bridge in to mono…….and AUX out shouold defenately be with a RCA connector.

 

[Batmobil3250]

@Douk Audio
It seems to be that Douk Audio A5 is using an analog filter which typically has linear roll off, can you help in showing how the frequency roll off looks like on speaker output when HPF is enabled.
Example, I was testing something similar: analog filter with linear roll off.
Setting 200Hz HPF resulted in roll off starting around 600-700Hz, something like this:
View attachment 427675

Is it how Douk Audio A5 expected to behave as well? Good point. I am also curios to see the slopes and frequency points. 18db/oct would be cool

 

[EJ3]

The A5 would benefit from being able to bridge in to mono…….and AUX out shouold defenately be with a RCA connector.

Amp Hacks: Can you bridge any amplifier? Bridge mode and how to do it without a bridge mode switch​

Barry Watson

35,793 views Apr 17, 2021
Looking to get the most out of your amplifier? Wondering if it's capable of bridged operation? Look no further! In this video, we'll show you how to tell if your amp is capable of bridging, explain exactly what the BRIDGE MODE switch does, and discuss the advantages and disadvantages of bridged mode.
But wait, there's more!
We'll also teach you how to bridge an amp without a bridge switch.
That's right, you don't need a fancy switch to get the most power out of your amplifier.
With our expert tips and tricks, you'll be able to bridge your amp like a pro.Whether you're a seasoned pro or a newbie to the world of amplifiers, this video has everything you need to know about bridging your amp for maximum power and performance. So what are you waiting for? Watch now and take your amplifier to the next level!

 

[Audionaut]

We'll also teach you how to bridge an amp without a bridge switch.

You don't trust people to get along with a Bluetooth transceiver, but you trust them to analyze a TPA3255 board, which is not designed for bridge switching, and to modify it if necessary.
That is interesting.

 

[EJ3]

You don't trust people to get along with a Bluetooth transceiver, but you trust them to analyze a TPA3255 board, which is not designed for bridge switching, and to modify it if necessary.
That is interesting.

What??? I use a Bluetooth transceiver system to send signals from a computer upstairs to a stereo downstairs.
Please explain yourself???

 

[Audionaut]

Please explain

That it must be used with a Bluetooth receiver of equal codec reception capabilities.

 

[EJ3]

Yes & what is wrong with letting someone know that when they might just presume that all Bluetooth receivers will accept all codecs?

 

[antcollinet]

Amp Hacks: Can you bridge any amplifier? Bridge mode and how to do it without a bridge mode switch​

Barry Watson

35,793 views Apr 17, 2021
Looking to get the most out of your amplifier? Wondering if it's capable of bridged operation? Look no further! In this video, we'll show you how to tell if your amp is capable of bridging, explain exactly what the BRIDGE MODE switch does, and discuss the advantages and disadvantages of bridged mode.
But wait, there's more!
We'll also teach you how to bridge an amp without a bridge switch.
That's right, you don't need a fancy switch to get the most power out of your amplifier.
With our expert tips and tricks, you'll be able to bridge your amp like a pro.Whether you're a seasoned pro or a newbie to the world of amplifiers, this video has everything you need to know about bridging your amp for maximum power and performance. So what are you waiting for? Watch now and take your amplifier to the next level!

What that video fails to make sufficiently clear is that most of these chip amp designs (including this one) are already bridged internally, so cannot be bridged to mono.

(It does mention internal bridging, and says to check continuity between the black terminals - but also states "most" amps can be bridged. This might have been true when the video was made - but with the explosion of TPA 32xx chip amps, is no longer (IMO))

 

[Krampi]

What that video fails to make sufficiently clear is that most of these chip amp designs (including this one) are already bridged internally, so cannot be bridged to mono.

(It does mention internal bridging, and says to check continuity between the black terminals - but also states "most" amps can be bridged. This might have been true when the video was made - but with the explosion of TPA 32xx chip amps, is no longer (IMO))

Is it possible in PBTL application, unless I misunderstood the intention.

TPA3255: TPA3255 PBTL mode ，if use 2Ω speaker ， will turn into overcurrent limit protection immediately - Audio forum - Audio - TI E2E support forums

Part Number: TPA3255 Hi ! It is need your help , the schematic as below , TPA3255 in PBTL mode ï¼if use 2Ω speaker ï¼ will turn into overcurrent limit protection

e2e.ti.com

 

[Audionaut]

Is it possible in PBTL application, unless I misunderstood the intention.

The TPA3255 is a high-efficiency Class-D amplifier that can be configured in different ways depending on the intended application. The three main configurations are stereo operation (Single-Ended, SE or Parallel Bridge-Tied Load, PBTL), mono operation (Bridged-Tied Load, BTL), and a flexible design that allows switching between both modes.

But I would never tinker with a TPA3255 circuit board that is intended exclusively for stereo operation.

 

[antcollinet]

Is it possible in PBTL application, unless I misunderstood the intention.

TPA3255: TPA3255 PBTL mode ，if use 2Ω speaker ， will turn into overcurrent limit protection immediately - Audio forum - Audio - TI E2E support forums

Part Number: TPA3255 Hi ! It is need your help , the schematic as below , TPA3255 in PBTL mode ï¼if use 2Ω speaker ï¼ will turn into overcurrent limit protection

e2e.ti.com

That is designed to be paralleled directly on the output of the chip (before the output filter). I've no idea if that will work paralleling after the filter. I suspect it will result in stability problems.

 

[antcollinet]

The TPA3255 is a high-efficiency Class-D amplifier that can be configured in different ways depending on the intended application. The three main configurations are stereo operation (Single-Ended, SE or Parallel Bridge-Tied Load, PBTL), mono operation (Bridged-Tied Load, BTL), and a flexible design that allows switching between both modes.

In BTL mode, two amplifier channels work together to drive a single speaker. One channel receives the standard signal, while the other channel receives the same signal but phase-inverted. The speaker is connected between these two outputs instead of between an output and ground. This configuration doubles the voltage swing, leading to higher power output compared to a single amplifier channel.

A stereo-only PCB design uses each half of the TPA3255 as an independent amplifier channel, with speakers connected between the amplifier outputs and ground. While simple and widely compatible, it lacks the option to increase power for a single channel, making it less suitable for high-power subwoofers. In contrast, a BTL-only PCB is permanently configured to bridge two amplifier channels into one, ensuring that one channel receives an inverted version of the signal while the outputs are wired to maximize power. This design delivers higher Output, making it ideal for subwoofers and PA systems. However, it sacrifices stereo functionality and is less versatile for different audio setups.

A switchable PCB provides the best of both worlds by allowing the user to toggle between stereo and mono operation via jumpers, DIP switches, or software control. This requires additional circuit elements, such as a signal inverter (e.g., an op-amp or DSP function) to provide the necessary phase inversion for BTL mode, as well as a relay or switchable connection to properly route the speaker terminals depending on the selected mode. While this design offers maximum flexibility and allows both standard HiFi stereo and high-power mono applications, it comes with a more complex PCB layout and requires a sufficiently powerful power supply for both configurations.

In summary, stereo-only boards are the simplest and most suitable for general HiFi applications, BTL-only boards maximize power output but lack stereo functionality, and switchable designs provide versatility at the cost of increased complexity. If you are considering a specific board, the choice will depend on whether you prioritize simplicity, raw power, or flexibility.

But I would never tinker with a TPA3255 circuit board that is intended exclusively for stereo operation.

You've missed the point that the TPA3255 has 4 single ended amplifier channels. Nearly all stereo amplifier implementations use these as two bridge tied pairs. They are then not able to be operated with a further BTL mode using the two pairs bridge tied again - doesn't work, will break the amp.

 

[Audionaut]

You've missed the point that the TPA3255 has 4 single ended amplifier channels. Nearly all stereo amplifier implementations use these as two bridge tied pairs.

Thank you, this also explains the almost equal output power for each channel in the mono-only devices compared to the stereo devices. I was assuming the usual circuit designs that I know.
I wonder what advantages a pure TPA3255 mono amplifier offers at all.