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Class D Switching Power Amplifiers and Power D/A conversion

Any full digital amp project(s) that may rival NAD C390DD?
Any full digital amp project(s) that may rival NAD C390DD?
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Old 21st September 2013, 04:44 AM   #31
craig in SD is offline craig in SD
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Originally Posted by bobistev View Post
Hi Craig,

Is the 7050 using the Zetex technology? Any chance you can post photos of the unit internals?
No photos of the internals. But a number of NADs specs for this unit are line item reproductions of the CSRA6000/CSRA6001 specs. See, for example, THD+N. The functions built into this chipset are ideal for producing an amp with the features of the D7050--e.g. unused amplifier outputs can be used for headphone or line level analog outputs (D7050 has one of each, and is on the low end of the available power range for this IC), and bluetooth streaming. I would wager good money this is what's inside. Is anyone else making such a good fit for this product?
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Old 27th September 2013, 06:36 AM   #32
craig in SD is offline craig in SD
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NAD D 7050 Network Receiver with Bluetooth®

Well, now, it appears CSR is advertising that their direct digital technology is in the D7050, so I guess that clears it up...
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Old 20th November 2013, 02:53 AM   #33
kerkula is offline kerkula  United States
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Default NAD drank the Apple juice

I was just about to by the 7050. It looks like a great product. I am sad to say, unless you own an Apple product (iphone or ipad) you really can't use this amp. You need one of these devices to configure the wi-fi or adjust the subwoofer output. NAD won't support any sort of android interface. There are probably reasons for this. The obvious one is that not only does one need to drop $999 for this amp but you also need to find spare cash to buy an ipad or iphone. Seems like a mistake to me. I really want this amp but not on those terms.

My hunt for the right FDA continues.

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Old 20th November 2013, 04:39 PM   #34
von Ah is offline von Ah  United States
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That is seriously disappointing.
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Old 15th February 2014, 01:02 PM   #35
kerkula is offline kerkula  United States
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Default Android app now available

NAD finally got around to it and made an android app available. I bought the d7050 and am enjoying it. It needed to break in over the course of a month. It sounded very good out of the box but doing even better now.

As for the app it is identical to the apple version which means not much. I suspect there's more functionality lurking in those chips than we are allowed to see.


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Old 27th May 2014, 07:45 PM   #36
audiolic is offline audiolic  Canada
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Originally Posted by soundcheck View Post
I havn't listened the NAD amp.

Though I listened to the NAD M51 (also DDFA ) + a class D amp at a friends place.
That combination sounded awesome.

I do run a tweaked DDX320 for quite some time ( which left my TP Buffalo plus Class-D amp behind)

I've done some tweaking on the DDX320 FDA. (You'll find an FDA article on my blog and discussions in the HifiMeDiy vendor forum.)

Without that tweaking it the DDX is IMO an average performer.
You probably are better of buying one of those 200-300 FDAs.

With my tweaks the DDX is IMO a great sounding device and pricewise
a steal. My mods didn't cost much. At a total of 150 $ (includes the LiPoFe batteries) a DAC incl. amp at this quality is hard to beat.

CSR with DDFA seems to offer a developments/evaluation board soon ( there's another thread over rhere @DIYA). That might be interesting.

NAD will also launch a new product line in July. Those FDAs will be called D7050 D3020. They come with USB input - DLNA/UPNP and wireless (7050) as well as bluetooth APX.
I'd say that these devices are gonna be very interesting. Keep the fingers crossed that they managed to built in even better soundquality then their older devices.
I'd be very tempted to try the big one.
hi there, do you know if your tweaks has been applied to new ddx320 2.2 version
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Old 28th May 2014, 06:34 AM   #37
soundcheck is offline soundcheck  Germany
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Some of them.

The battery supply which made a big difference in my case they skipped for obvious reasons.

However. The DDX320 is no longer sold. Now they sell a (or better two) USB-FullDigitalAmps which are based on the same technology. I havn't tried the new device myself though.

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Old 28th May 2014, 12:29 PM   #38
AudioLapDance is offline AudioLapDance  Canada
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UD20 and UD80 both use the Savitech SA9023 USB receiver and then pass on I2S (with control I2C on the side) to PWM STA335 20W (UD20) or STA328 80W (UD80)

Anyone know where to find the SA9023 datasheet?

Just about to mod my UD20

UD20 top.jpg

UD20 bottom.jpg

UD20 20W STA335

UD80 80W STA328

PS oh ya, check out the un-used features of these kinds of chips (and that's 2007/8)

■ Wide supply voltage range (5 to 24V)
■ 4 Power Output Configurations – 2 channels of ternary PWM (stereo mode)
(2 x 20 W @ 8 Ω, 18 V) – 3 channels - left, right using binary and LFE
using ternary PWM (2.1 mode) (2x10W + 1x20 W @ 2 x 4 Ω, 1 x 8 Ω, 20 V)
– 1 channel PWM output (parallel-mode) (1 x 40 W) – 2 channels of ternary PWM (2 x 20 W) + stereo lineout ternary
■ 2.1 Channels of 24-Bit DDX®
■ >94dB SNR and Dynamic Range
■ Selectable 32 KHz to 192 KHz Input Sample Rates
■ I2C control with Selectable Device Address
■ Digital Gain/Attenuation +48 dB to -80 dB in 0.5 dB steps
■ Soft Volume Update
■ Individual Channel and Master Gain/Attenuation
■ Dual Independent Limiters/Compressors
■ Dynamic Range Compression or Anti-Clipping Modes
■ AutomodesTM
– 15 Preset Crossover filters
– 2 Preset Anti-Clipping Modes
– Preset Nighttime Listening Mode
■ Individual Channel and Master Soft and Hard Mute
■ Independent Channel Volume and DSP Bypass
■ Automatic Zero-Detect Mute
■ Automatic Invalid Input Detect Mute
■ 2-Channel I2S Input Data Interface
■ Input and Output Channel Mapping
■ 4 x 28-bit User Programmable Biquads (EQ) per channel
■ Bass/Treble Tone Control
■ DC Blocking Selectable High-Pass Filter
■ Selectable De-emphasis
■ Sub Channel Mix into Left and Right Channels
■ Advanced AM Interference Frequency Switching and Noise Suppression Modes
■ Selectable High or Low Bandwidth Noise Shaping Topologies
■ Variable Max Power Correction for lower fullpower THD
■ Selectable Clock Input Ratio
■ 96 KHz Internal Processing Sample Rate, 24 to 28-bit precision
■ Thermal Overload and Short-circuit Protection embedded
■ Video Application: 576 x fs input mode supporting
■ PSSO-36 Slug Down package.



Last edited by AudioLapDance; 28th May 2014 at 12:38 PM.
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Old 30th May 2014, 05:58 AM   #39
audiolic is offline audiolic  Canada
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i need coax digital input..
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Old 19th November 2014, 06:14 PM   #40
Yves Smolders is offline Yves Smolders  Belgium
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FWIW - I know it's not what you are looking for, but the combo of NAD M51 (or NAD C 510, almost same as M51) with Ncore amplification behind it is pretty amazing. It's not a pure PWM amplification, but it's the best thing I've heard driving B&W 802 diamond speakers, short of the top of the range devialet. M51 is discontinued and being dumped at low prices
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