My RPi + Allo Boss DAC + TPA3116D2 Amp

[Aniket]

JLS / Aniket, I am using an unregulated LPS as of now, so if the line voltage goes down or up, the Amp board also gets lower or higher voltages. Can I add a regulator between the rectified supply and the Amp, say, made of two LM338 5A regulators in parallel with a 0.5R 5W resistor in series followed by a large capacitor bank (to get a 10A 24V regulated PS) ?

Although a regulated supply is better for any amplifier, specially for a Class D amp. But, if you have a large capacitor bank and a solid transformer , then adding a regulator wont do much of a difference. It wont be audible.

Even if there is fluctuation of +/-10V in the mains, the DC after rectification will vary by 2-3V only. If you wish to go for a regulated supply then better go for a regulator using discrete high current devices.

Regards,
Aniket

 

[jls001]

JLS / Aniket, I am using an unregulated LPS as of now, so if the line voltage goes down or up, the Amp board also gets lower or higher voltages. Can I add a regulator between the rectified supply and the Amp, say, made of two LM338 5A regulators in parallel with a 0.5R 5W resistor in series followed by a large capacitor bank (to get a 10A 24V regulated PS) ?

You can add regulation but I'm not sure if there will be sonic benefits in doing so.

The variation in the rectified DC voltage due to AC mains variation will be nominal, say a volt here and there. If voltage drops you will lose some amount of output power, but I don't think it will be even noticeable.

 

[SanjeevM]

I am operating this board at 23v now. Is overvoltage protection required, as the datasheet says 26v max? The 3v head will mean a 36v variation of primary voltage.

 

[vbutani]

Very interesting! I have one query as follows :

I have Denon X2300w AVR and I am planning to use allo boss DAC in pure direct mode.

By chance can someone advise, I should build the audio amplifier as well as done by Sanjeev or existing AVR amplifier would be sonically good as I read somewhere that AVR has average audio quality as compared to integrated amplifier?

Thanks.

Sent from my Moto G (4) using Tapatalk

 

[Aniket]

I have Denon X2300w AVR and I am planning to use allo boss DAC in pure direct mode.

By chance can someone advise, I should build the audio amplifier as well as done by Sanjeev or existing AVR amplifier would be sonically good

Your existing AVR has discrete , class AB, 7 channel amplifier. A class D chip amp is no match even for an under built Class AB discrete amp based on sound quality.
In the manual it says 95W pc 8ohms, 0.08%THD, 2 ch driven. I believe that you will probably use only 2 channels for listening music, through ALLO Boss DAC. So, you will degrade sound if you go for a Class D chip amp compared to the receiver.

AVR has average audio quality as compared to integrated amplifier?

Both of these are made for different applications. The former for home cinema and other for HiFi stereo music. in most cases AVR have mediocre and under built amp section compared to integrated amplifiers.


Regards,
Aniket

 

[TCHeN]

Very interesting! I have one query as follows :

I have Denon X2300w AVR and I am planning to use allo boss DAC in pure direct mode.

By chance can someone advise, I should build the audio amplifier as well as done by Sanjeev or existing AVR amplifier would be sonically good as I read somewhere that AVR has average audio quality as compared to integrated amplifier?

Thanks.

Might be a hit and a miss or bang on target, hard to say unless one listens to both.

Typically though AVRs kind of suck compared to dedicated to stereo amps, but one would think that the AVR will triumph in this case (if the stereo amp budget is less and it's class D).

 

[vbutani]

Thanks Aniket and TCHen for thorough information. it cleared many doubts.

Regards,
VB

Sent from my Moto G (4) using Tapatalk

 

[jls001]

I can see that old biases against class D still rear their heads

Never mind. Each to his own. There are those of us who have happily moved on from AB and A to D.

 

[Aniket]

I can see that old biases against class D still rear their heads

Never mind. Each to his own. There are those of us who have happily moved on from AB and A to D.

Hi jls001,

It's not that I am against Class D amplifiers. In the above query class D and class AB were compared on sound quality. And if you compare a discrete class AB vs a class D chip, the former will win in every aspect except efficiency. I talk about logical and scientific facts only rather than subjective opinions and I am crude on it.

Now, if we talk about class D, of course it is the future of amplification and sound reproduction. but, factually class D chips have to improve a lot to near linear amplifiers on sound quality-This is what Mr. Douglas Self says.
And ask any amplifier designer or a music creater, (not a music listener) what they use for recording music.

Couple of weeks ago, this was my own experience, I had a chance to hear Nuprime IDA-8 integrated amplifier, which is a Class D amp, compared to Sonneteer Alabaster, which is a hardcore Class AB amp.
Honestly, there was nothing we can differentiate sonically between the two, except that Nuprime had better sound stage and amazing imaging. But again, its a discrete Class D amp, more of a hybrid-Class A+D.

Summing up all, I would say that Class D is the future. I am for it. But class D chips should stay where they belong. i.e Boomboxes.

BTW, i am also designing a discrete Class D amplifier

Regards,
Aniket

 

[SanjeevM]

I am enjoying Class D sound. Will try the 3251/3255 chips, but still, I will like to hear a better-than-this Class A amp, which I have not found yet.

That said, to each his own !!

My experience with two tube amps that I heard was that their mids n highs were very smooth, esp suited for jazz but it was lacklustre in bass.

 

[jls001]

Hi jls001,
It's not that I am against Class D amplifiers. In the above query class D and class AB were compared on sound quality. And if you compare a discrete class AB vs a class D chip, the former will win in every aspect except efficiency. I talk about logical and scientific facts only rather than subjective opinions and I am crude on it.

I haven't done a comparison of my TPA3118 (with various mods) against a class AB AVR receiver but have had the opportunity to compare it to MyRef Rev C (LM3886 chip based design by Mauro Penasa and Linuxguru), a 50W A/AB Yaqin EL34 tube amp, a friend's 180W class AB power amp, and my own (factory made, not a DIY effort) 80W class A amp. That's a fairly varied range of amplifiers. It was very close to the performance of the class A and the 180W AB. The other two instances were a walkover by the TPA3118. Almost no contest, really.

I liked the TPA 3118 a lot after I completed building and modifying it, but never expected it to sound so good. I did it as a fun, cheap, little project out of curiosity aroused by the long thread over at diyaudio. I was taken by (a very pleasant) surprise. No, AB doesn't win every aspect except efficiency. If one goes by the spec sheet of the 3116/3118, it is but natural to expect them to sound rubbish (10% THD at full power) but the reality is no one pushes these amps to full power or near full power constantly. At regular listening levels they play comfortably in their linear range. And within the linear range, there is absolutely no digital glare or etch or audible distortions. Of course I can't speak for other class D chips since I've not heard them.

Now, if we talk about class D, of course it is the future of amplification and sound reproduction. but, factually class D chips have to improve a lot to near linear amplifiers on sound quality-This is what Mr. Douglas Self says.
And ask any amplifier designer or a music creater, (not a music listener) what they use for recording music.

Yes, considering the amount of interest evinced by class D, implementations will surely improve.

Summing up all, I would say that Class D is the future. I am for it. But class D chips should stay where they belong. i.e Boomboxes.

I think many of the class D chips like STA516 were primarily designed for PA but have been embraced by the hifi community for their surprisingly good sonics. TPA 3116/3118/3130 datasheet does list the following applications:
Mini-Micro Component, Speaker Bar, Docks
After-Market Automotive
CRT TV
Consumer Audio Applications

I think they're being conservative and polite in mentioning the last one I say they will compete very well with many of the entry and mid level hifi brands. But the caveat is there are hardly boxed-up, ready to be plugged in offerings except perhaps from Alibaba/AliExpress. It's heartening to see a class D offering now made available in our own Hifimart. I hope to hear it for myself someday soon.

BTW, i am also designing a discrete Class D amplifier

That's fantastic, Aniket!

Hopefully I'll be able to buy a board/kit from you when you're done.

What kind of modulation scheme and switching frequency are you planning?

 

[TCHeN]

I can see that old biases against class D still rear their heads

Never mind. Each to his own. There are those of us who have happily moved on from AB and A to D.

Ha ha not my intention.

My response was a guesstimation for the amp being from the Allo stable (the same as the DAC). An AVR would win hands down.

 

[SanjeevM]

I think they're being conservative and polite in mentioning the last one I say they will compete very well with many of the entry and mid level hifi brands. But the caveat is there are hardly boxed-up, ready to be plugged in offerings except perhaps from Alibaba/AliExpress. It's heartening to see a class D offering now made available in our own Hifimart. I hope to hear it for myself someday soon.

The Texas Instruments datasheet for TPA3251 chip says that the chip is suitable for
Blu-ray Disk / DVD Receivers
High End HTiB Systems
AV Receivers
High End Soundbar
Mini Combo Systems
Active Speakers and Subwoofers

Wait for the TPA325x boards to become available commonly, and we will witness a whole new level of performance at budget prices, which will be difficult to beat. Presently, the boards cost $68 or so, say INR 4K. Add INR 5K for an uber-beefy LPSU (or 1K for a SMPS), and voila, in Rs 9,000 you have a light-weight & cool but a high performance Amp at your service.

When the TPA325x chips were demonstrated at a show, they left the listeners mesmerised. Obviously, TI is betting big, so better chips are bound to hit the market as time passes.

The future is bright for Class-D. Hot and heavier Class-A, prepare to make space

 

[vizeta]

Thanks for sharing about it. After reading about Boss DAC I ordered one (Boss player Kit) from diyaudiocart.
The Boss player came with Volumio loaded but it was crashing every time during my library scan (over the smb mount).

I am using two separate SD cards loaded with picoreplayer & Moode (bought license key). Moode for Air play support (however it is disconnecting frequently) and PCP for simplicity and full compatibility with Squeezebox touch.



I was planning to buy Volt+ & attenuator kit, but there is a new model of Allo Volt+ planned. Looks great.
It is scheduled to in 3rd or 4th week of September.
Decided to wait or it.

 

[SanjeevM]

You could take a 8gb card and put Volumio on it. That should work, and not have the problem of crashing.

Sent from my ASUS_Z00AD using Tapatalk

 

[vizeta]

You could take a 8gb card and put Volumio on it. That should work, and not have the problem of crashing.

Sent from my ASUS_Z00AD using Tapatalk

Allo shipped the kit with Volumio installed on 8gb card. It seems Volumio doesn't like some meta-data in my music library. I tried to debug it, but the crash point (technically it's not a crash, the system gradually becomes slow after some point) was always different.

 

[SanjeevM]

Allo shipped the kit with Volumio installed on 8gb card. It seems Volumio doesn't like some meta-data in my music library. I tried to debug it, but the crash point (technically it's not a crash, the system gradually becomes slow after some point) was always different.

You need to check the name of each song in your library. Try deleting all folders, then adding them one by one.

I recently bought the TPA3251 board, and am running it with a 36.6volts linear PSU. The sound is much more open, highs are clearer, lows are distinct, and the background is blacker, as compared to the 3116d2. So, presently, the 3116d2 has been de-commissioned.

The rest of the player, I. e. the RPI and BossDAC is running strong, feeding the TPA3251.

 

[sree0320]

Dear FMs,

I recently bought the TPA3251 board, and am running it with a 36.6volts linear PSU. The sound is much more open, highs are clearer, lows are distinct, and the background is blacker, as compared to the 3116d2. So, presently, the 3116d2 has been de-commissioned.

The rest of the player, I. e. the RPI and BossDAC is running strong, feeding the TPA3251.

Where did you bought it from. What's the price?
Please share the link

 

[SanjeevM]

Where did you bought it from. What's the price?
Please share the link

My friend brought it from US. It's available on eBay, from 3eaudio.

 

[vizeta]

My friend brought it from US. It's available on eBay, from 3eaudio.

seller not shipping to India :sad: