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Review and Measurements of Pro-Ject Pre Box S2 Digital

Veri

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Didn't the Teac use a velvet sound chip?
Yes it did.
Wait this Velvet sound is actually a thing ??

"The AKM AK4493 Premium DAC with VELVET SOUND™ technology is the new flagship 32-bit stereo Premium DAC. Digital input supports PCM inputs up to 768kHz and DSD input of 2.8MHz/5.6MHz / maximum 11.2MHz the industry's highest level. Internal circuit employs a newly developed 32-bit Digital Filter for the ultimate in sound quality and musicality"

Sounds like a whole lot of marketing BS :rolleyes:
 

sonci

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Are CD players possible to measure?
It would be interesting to see a Sony ES series or some players with TDA1541.
 

RayDunzl

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Are CD players possible to measure?
Yes.

It depends...

I think you could create a CD with the REW Sweep tone. Run the output back to REW for analysis.

Or create the CD with whatever test tone you want to look at.

Or some similar method with other analyzers.
 

amirm

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Are CD players possible to measure?
Not easily since the analyzer can't control them. I can run Jitter and distortion tests but not linearity.
 

RayDunzl

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I can run Jitter and distortion tests but not linearity.
Create a 1 bit file, 2 bit file, 3 bit file, etc... stare and compare...
 

amirm

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Create a 1 bit file, 2 bit file, 3 bit file, etc... stare and compare...
I do plan to make a limited version of that for USB testing but it is a lot more work to run.
 

pos

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Pos, rePhase is fantastic. I used it for my PC/active system.
Thank you, glad you like it :)
Just saw your system, very impressive!
Are you considering replacing your Rosetta DAC with several of the new breed tested around here? (mostly mobile ESS based)
I am asking that because I recently hesitated between an RME ADI8 (also considered Lavry blue, Avalon 8, Mytek 8x192, etc.) and several DX7s, and opted for the second option...
 
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Are you considering replacing your Rosetta DAC with several of the new breed tested around here? (mostly mobile ESS based)
I am asking that because I recently hesitated between an RME ADI8 (also considered Lavry blue, Avalon 8, Mytek 8x192, etc.) and several DX7s, and opted for the second option...
Not currently, the Rosetta supports up to 24/192, I also use its ADC/inputs for analogue sources. I like that with the Lynx interface I can use the clock in the Rosetta too.

If I change anything it will be the interface, being PCI its getting on a bit. Minidsp have an interesting looking unit https://www.minidsp.com/products/usb-audio-interface/u-dio8.
 

pos

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The minidsp UDIO8 is what I am currently using on a dedicated linux machine, and so far it works flawlessly!
Did not test the input part though, with the ASRC (no word clock connection, contrary to the Lynx).
 
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L0rdGwyn

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The Pro-ject is looking like an appealing option at the $3-400 USD price point, but doesn't appear to be widely available in the US (as far as I can tell). It can be purchased from the UK site Analogue Seduction with fixed-rate international shipping and Value Added Tax excluded. Comes out to around $366 USD with the current exchange rate :)
 

amirm

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OK, here is the output impedance measurement:

upload_2018-2-22_15-39-25.png


As we see, it is a low 1.9 ohm measured at 1 kHz. I also measured it at 100 Hz and it creeped up to 2.2 ohm.

Unloaded output level is very disappointing at just 2 volts.

Listening with both Sennheiser HD650 and HiFiMan HE400i, I had to listen at max volume of 0 dB. Subjective impression was anemic.

Switching to Topping DX7s was night and day. I had to keep the level at some -15 dB and subjectively bass performance and resolution was far better.

I then tried it with Grado SR60e and now there was plenty of power and good fidelity. Listening level now dropped to -10 dB.

Specs say that the Grado is less efficient that the Sennheiser???

In summary you need to pick your headphone carefully. As it is, I would say this is more of a DAC than DAC+headphone amp.
 
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OK, here is the output impedance measurement:


As we see, it is a low 1.9 ohm measured at 1 kHz. I also measured it at 100 Hz and it creeped up to 2.2 ohm.

Unloaded output level is very disappointing at just 2 volts.

Listening with both Sennheiser HD650 and HiFiMan HE400i, I had to listen at max volume of 0 dB. Subjective impression as anemic.

Switching to Topping DX7s was night and day. I had to keep the level at some -15 dB and subjectively bass performance and resolution was far better.

I then tried it with Grado SR60e and now there was plenty of power and good fidelity. Listening level now dropped to -10 dB.

Specs say that the Grado is less efficient that the Sennheiser???

In summary you need to pick your headphone carefully. As it is, I would say this is more of a DAC than DAC+headphone amp.

Nice to see a low output impedance on this unit. It is a shame that the headamp power output is so low, only 68mW at 32Ohms iirc. Does limit the unit, can't really use it as a one in all for all situations.
 

RayDunzl

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Sal1950

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The Pro-ject is looking like an appealing option at the $3-400 USD price point, but doesn't appear to be widely available in the US (as far as I can tell). It can be purchased from the UK site Analogue Seduction with fixed-rate international shipping and Value Added Tax excluded. Comes out to around $366 USD with the current exchange rate :)
Audio Advisor carries them, out of stock now but due in early April.
http://www.audioadvisor.com/prodinfo.asp?number=PRPRBS2D
 

sonci

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Does Topping really test every device on the analyzer?
I think they test the model, it would be stupid to test every device on AP.

I was looking at Topping D30 test page, and even though Amir hasn't put all the new graphics there, I wonder if we can blindly ABX D30 and Dx7, just by listening to the Dac section, not accounting the headamp.
Does any of the test show clearly that there is an audible difference between them?
 

Jimster480

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I think they test the model, it would be stupid to test every device on AP.

I was looking at Topping D30 test page, and even though Amir hasn't put all the new graphics there, I wonder if we can blindly ABX D30 and Dx7, just by listening to the Dac section, not accounting the headamp.
Does any of the test show clearly that there is an audible difference between them?
They actually test every single device on an analyzer.
I have bought 2x A30's and a D30 and a DX7.
All had measurement papers in the box, but then again I've had the A30/D30 for a year already before it was popular.

I could probably ABX the D30 and the DX7 given the right tracks and headphones.
I did spend many times AB testing the two of them and there are a few songs that have specifically more details with the DX7 vs the D30. The difference is not huge and you have to listen critically.
The one thing though is that the D30 has more jitter via USB and this is present while the DX7 never has a pop or crack no matter how long you listen.
Also the D30 is slightly warmer sounding vs the DX7. I did this testing by feeding my DX7 or my D30 through the same A30. Later on when I got my O2 amp I did some additional testing feeding my O2 with either the DX7 or D30. The tests weren't blind but as I said there are differences which are easier to identify especially listening back to back given the right tracks.
Additionally the D30 had some things where sometimes male vocals were slightly recessed in things like TV shows.... its very weird and I did extensive testing with this to find that it doesn't always happen.
 
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