Fully Digital amplifiers

Posted by HiFimeDIY 15/07/2016 33 Comment(s)

The UDP80 fully digital amplifierEdit: Now available for purchase
A fully digital amplifier is a PWD (pulse width modulation) amplifier with no A/D conversion, no preamp or any analog signal path before the final output stage. It’s like you remove a bunch of parts and just have a single chip to amplify the digital signal directly to speaker level. You can think of it like a huge powerful DAC chip that connects directly to the speakers. - However the term powerDAC is often used for an amplifier that has a DAC chip built in in addition to the amplification stage. That’s not what this is. A fully digital amp has only one stage converting the digital signal to high level speaker level signal. 


We like the minimalistic approach and it’s a commonly accepted opinion that parts in the signal path (parts that the audio signal goes through) will affect the sound quality. That’s why people spend hundred of dollars on expensive audiophile capacitors, and that’s why our Sabre DAC with no capacitor on the output sounds so good. 


So for a powerful amplifier, what could be better than to remove the need for a DAC and preamp all together!


The sound from the true digital amps is very clear and natural and make the class D amps sound muddy in comparison.


Our new UDP80 amp uses similar technology as our DDX320 amp that’s only sold as DIY (and currently sold out) and the popular UD80 USB amplifier. It has an USB input that accepts all sample rates and files up to 96kHz/24bit and there is now also an optical input that accepts up to 192kHz/24bit. The amp will automatically detect the input source. In fact there is only one control on the amp, the volume control that is of course digital. The amplifier goes to standby when the volume control is set to 0. It will be available in a case as a ready to use product.

More of on the UDP80 coming soon. 

33 Comment(s)

18/07/2016, 08:52:15 AM

Hi. It would be great if you could expose i2s headers on the board for DIY. There are quite a few of us on DIY Audio building multi-channel active speakers and having to modify other DD amps such as the d802 or v200 to allow i2s input. A multichannel USB->i2s card plus multiple DD amps makes an extremely attractive setup. Rgds, Rob.

19/07/2016, 08:23:30 AM

Hi and thanks for the suggestion. it could be done, but we would need to add another switch to be able to switch to the i2s signal. We use a logic switch like 74HC157 to switch optical and USB, another switch could make more delay. We could add pads on the optical path, and then you could use i2s if you remove the optical parts. only some resistors need to be unsoldered. Would that be of any help ?

Peter Pataki:
20/07/2016, 08:01:27 PM

Hi Rob, This multichannel fully digital amping sounds extremely interesting (especially when combined with I2S). How can you combine more of these amps? How do you get the I2S signal from the computer? I would love to hear more about that Thank you in advance Peter

23/12/2016, 02:54:04 PM

Thanks for the reply on the i2s input. Yes, this would be brilliant and unsoldering resistors would be no problem. Even better would be if both inputs were routed via jumpered pins so we could simply remove the link jumper and tap in directly to the i2s. Personally I would disconnect both, substitute a co-ax spdif/i2s board for the optical input, disconnect the USB and directly tap into the i2s from i2s output on my DSP crossover. But if the flexibility is there to access i2s input different folks will use it different ways. I could do with three amps like this for my active speaker setup :-)

18/07/2016, 08:54:32 AM

Hi, the UD80 was discontinued some time ago, just wondering how does this one differ?

19/07/2016, 07:56:50 AM

This new UDP80 has optical input also, and it has some improvement in the circuit and different coils.

18/07/2016, 09:01:06 AM

Does this new amp have a pre out for a subwoofer input?

19/07/2016, 07:57:26 AM

It doesn't have a pre out. But the bass from this amp is quite good.

18/07/2016, 09:30:54 AM

What is the output power? Will there be a remote control? Thanks.

19/07/2016, 08:01:27 AM

2*80W@8ohm, 2*50W@4ohm. There isn't a remote, just the on board volume control. Minimalist design on this amp :)

18/07/2016, 10:01:25 AM

Hello, Good idea for this "FULLY DIGITAL AMPLIFIERS". Can yo tell me the SNR (db) and power for 4 Ohm ? Thank-you

19/07/2016, 08:00:45 AM

100db SNR and 2*50W @ 4ohm (2*80W@8ohm).

dennis deacon:
18/07/2016, 04:35:58 PM, www.d-sonic.net

I am interested in your UDP80 amplifier technology. Does this require a DAC at the speaker or do you provide the DAC at the end of the amplification chain?

Hifimediy DAC:
19/07/2016, 08:03:41 AM

This amp outputs an analog speaker signal, so there is no need for a DAC. You can think of this amp as a powerful DAC.

Ian Ross:
18/07/2016, 04:44:28 PM

Will it also include SPDIF coaxial input by wire as optical is not that reliable at higher rates 192khz/24bit. As well will SPDIF input include various standard rates i.e., 44.1,48.0,88.2,96.0,176.4 and 193 kHz and bit widths i.e., 16, 24 and 32. Looking forward to the release of this amp as it has features I have been looking for some time. My concern will be how it handles the inevitable CLICKS and POPS that occur on occasion and possibly damage speakers with all digital amps.

19/07/2016, 08:24:47 AM

This will only have spdif optical and USB. We haven't experienced any clicks and pops in our testing.

Alan Ballagh:
20/07/2016, 09:14:19 AM

I've been waiting for this! Can you please tell me how the volume is controlled? Ti used some kind of voltage variation on the output of there pwd amp which seems the only way to go for me, anything that reduces bit's even with a 32bit ref is a compromise I think. I've tried 32bit digital volume I think on my squeezebox Touch and it's not great at high ish attenuation, ie lower volume settings.

HiFimeDIY Web:
21/07/2016, 03:14:25 AM

Hi, yes the MCU reads the potmeter value and control the volume setting in the STA328 chip.

20/07/2016, 09:50:16 AM

What USB chip is used ?

21/07/2016, 03:10:16 AM

The SA9023 is used, the same as in many of our Sabre DACs.

20/07/2016, 06:25:49 PM

Hi, good news ! The chipset will be the STA326/STA328 or other ? Is the USB Asynchronous ? Please include a USB isolator.

21/07/2016, 03:11:16 AM

Yes it's the sta328, adaptive USB with SA9023. There is no USB isolator, but you could connect our USB isolator between the amp and the computer.

29/07/2016, 01:31:39 AM

When will the digital DDX UDP80 be available in a case? How much is the amp? Thank you, Rick

29/07/2016, 06:44:03 AM

Hi, in 4 to 6 weeks probably. The price will be similar to the UD80 amp.

30/07/2016, 11:01:27 AM

a product I really like buy is a complete 3-channel fully digital speaker-amplifier-module - including powerstage, some dsp processing for crossover and chassis equalizing, powersupply, and a proper frontend for this usecase. A lot of diy speaker builders would be really happy, but there is virtually no offer on the market. Until somebody recognises the demand i would be happy with some powerstages with i2s input only, doing my own input and signal processing stages. with regards /ropf

10/08/2016, 11:54:44 PM

Really like the concept of this amp. With 2 * 80 Watt the quality of the power supply is crucial. Probably a simple pin connector for the external power supply will not be sufficient to handle high peak currents. Maybe you can pay some attention to this!

15/08/2016, 09:03:13 AM

Hi, yes we have thought about this, and will use a high current capable connector.

12/08/2016, 09:56:53 AM

Hello, I have two questions : why the power is more in 8ohm than 4ohm (often is opposite) ? ; I think the USB/SA9023 can be Asynchronous, why the choice to Adaptive on this fully digital amplifier ? Thank-you for your answers.

15/08/2016, 09:05:20 AM

Hi, the limitation for the output wattage in this design is the current, as 4 ohm requires more current. That's why the 8 ohm wattage is higher. We made it adaptive as the difference is not big.

20/08/2016, 11:55:31 AM, gooogle.com

Hi! Very interesting thing! Can't wait to try it! But how about frequency response graghs? I can't find it for sabre dac 9018 also :( Only a few people can buy an audiophile hardware blindfold trusting a few beautiful words about it. Is it a top secret information? I think it will be appreciated better than words.

05/09/2016, 10:09:36 AM

Hi, we will have some measurements graphs available soon.

30/08/2016, 08:55:54 AM

This is great news, I'm very interested in testing this digital amplifier. Comment above says it should be available in no time now, max 2 weeks, isn't it? Otherwise can we subscribe to an alert?

04/09/2016, 03:04:17 PM

Hi, I am really interested in the upcomming product and I think it should be a big hit with a little bit of advertising. But I have a question here: will the USB input support OTG also? I think that could be a big catch for all the smart phones/ tablet users. How about a Bluetooth 4 (4.1) Apt-x add on? I know it's not considered Hi-Fi by many people but it will add a wireless solution. Maybe, It might be easier to add OTG functionality instead Bluetooth... Thnks for your answers.

05/09/2016, 10:12:32 AM

It uses the SA9023 usb receiver, same as our Sabre and Sabre 9018 DACs. It does support OTG, but that's more about the phones. Some phones still doesn't support OTG. This amp will support the same phones as the Sabre DAC, Sabre 9018 DAC and the new Android 9018 DAC.

When is release date?:
05/09/2016, 09:57:27 AM

When will this be released? Cheers

16/09/2016, 06:15:16 AM

Any news regarding the availability? Thx.

16/09/2016, 03:22:32 PM

I'm also looking for a release date. Could you please give us an update?

HiFimeDIY Web:
22/09/2016, 02:34:55 AM

Hi, it is available now, first units will ship next week. You can order here: http://hifimediy.com/upd80-usb-spdif-digital-amplifier

19/09/2016, 07:22:38 AM

Hi! I have your 9018 usb dac, so here's a question: your old UD80 amp had 100dB SNR, new 9018 dac has 122dB SNR, my old analog amp gives 112dB SNR. So won't it be worse for me with the new UDP80 instead of 9018 dac + old amp? The speakers are yamaha ns-6490 and i love it, all the frequencies are amazing. But in my case it gives a very poor low bass in amp's direct mode, so i had to add a sub-woofer for the low bass. (I'm not a fan of bass and I hate any subs, but I really had to) May be it is my amp cutting from 100 hz to the left. Im afraid, that it can be the speakers fault, so I can get the same result with your new UDP80 amp. But it has no out for sub-woofer. Please, tell a few words about my hesitates.

HiFimeDIY Web:
23/09/2016, 03:39:45 AM

You can't just look at the numbers. This is a different technology and the short analog signal path has some benefits. Maybe you can connect your source to the sub.

Colin Canfield:
22/09/2016, 05:12:18 AM

It looks great, but a couple of questions. - what DAC chip you use in this, or this also handled by the USB host ? - since the negative speaker outputs cannot be shorted is it possible to drive a headphone with this?

HiFimeDIY Web:
23/09/2016, 03:37:57 AM

There is no DAC chip, only the amplifier chip, you can think of that as a powerful DAC chip. You can drive a headphone if it's wired with separate negatives. We have used these amps with hard to drive Hifiman HE5, sound great.

Nick T:
22/09/2016, 12:00:53 PM

Hi Impressed so far but can you advise if it will be available board only for DIY? Can you confirm the physical dimensions of this cased version please?

07/10/2016, 09:35:01 PM

At last it's there for sale! But I'm quite surprise by the DC-in small jack for a 6A (36V) current... How does it behave with such load?

HiFimeDIY Web:
17/10/2016, 06:01:18 AM

The DC plug we use is rated at 10A.

19/10/2016, 12:42:40 PM

Hello, Did make a comparison of this FDA with the competition like the QA960, the Q5 Pro or the FA802C ? Are the SMPS power supplies a good option to feed your UDP80 ?

Carlo Pacetti:
21/10/2016, 02:01:44 PM

Hi! Very nice amp! Any hope to have the USB input extended to 192kHz/24bit?

19/11/2016, 12:39:50 AM

Hi, will you make this type of amplifier for headphone ?

26/11/2016, 12:47:14 PM

Hi! Regarding the following text in the description of UH1, "It also has optical INPUT which will redirect the optical signal to USB/computer. Note: The SPDIF/OPTICAL input does not go to ANALOG output". Does this mean that I can't connect an optical cable from an Apple TV and then connect the analog output to my amplifier?

HiFimeDIY Web:
27/11/2016, 05:29:49 AM

Hi, that is regarding the Uh1 dac, not this udp80 amplifer. The UDP80 amplifier accepts optical SPDIF signal directly.from your Apple Tv.

29/11/2016, 07:49:41 AM

I posted the question under the wrong product, sorry for that :-(. My question is regarding the DAC UH1.

13/12/2016, 06:20:09 AM

Hi I use one of those since few weeks.....well,coming back to class D or T amp is no longer an option ;-) Also sounds IMHO far away better than QLS amp I had (far more expansive). Nothing aggressive, real nice bass. I use it with 24VDC regulated PS.

15/12/2016, 05:55:53 AM

Hi! I got my UDP80 a few weeks ago and saved a little bit by buying a cheap 36V 3A power adapter off Amazon. It is incredibly clear and POWERFUL even with only half (3A vs 6A) the amperage it can take. Only one problem. ***I want another one to run my woofers! How do I run two of these together?*** I REALLY wish you had a line out on this that I could run into a second one :-( I am using the camera kit adapter on my iphone to get the digital signal out. Is there a digital EQ / Preamp available that can help? I WANT MOAR UDP80!

04/01/2017, 03:10:45 PM

You can use a mini dsp in full digital domain,

28/12/2016, 01:44:48 PM

Any plan to make a headphone version? You can even probably get away making it balanced if it has to.

Chris Lukas:
07/01/2017, 06:30:24 PM

I'd use a USB --> spdif converter for the iPad and then an all-optical splitter for the spdif so you can run two UDP80

16/01/2017, 10:08:54 PM

If I drive 2x or 4x UDP80 boards (2way or 4way active stereo speakers) I need to alter the volume control simultaneously on all channels. Like to alter the level from a DSP preamp with remote control etc. How does the volume control work on the board. Can see that there is a potentiometer. Can this be replaced with some kind of analogue voltage level or is there other alternatives that you have thought of.

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