Agreed.

So, I was expecting 4AP to look similar to 4AI (for these sine-wave sweeps at least). Actually, it is pretty similar above 20KHz... but there is a slight HF roll-off beforehand. I guess this due to artifacts above 88.2KHz, which I can't measure.

In which case, I don't understand is why 4AP is more rolled off than 4_no_filter at ~20KHz...

Mani.

I did this a while back, but with some new filters in XX, I thought it'd be interesting to repeat it.

I have a 16/44.1 wav file that sweeps from 20Hz to 20KHz in 33 seconds at a constant level. So, I simply play this file in XX and monitor the output of XX using RME's 'Digicheck' software.

A few notes:

1. I don't think it's wise to equate any of these graphs with SQ.
2. I'm not sure what happens below 100Hz with 4x upconversion applied - a bug in the RME software maybe?
3. My ADC/DAC is capable of 4x upconversion internally - the output looks identical to 4AI in XX (I had to use a separate laptop/card to generate a 16/44.1 input for my ADC/DAC and then monitored the 24/176.4 output from the ADC/DAC on my main PC - but I forgot to capture this image).

Peter, are these graphs as you would expect? I was surprised by the 4AP graph...

Cheers,
Mani.

 

KUOYAO, I notice you have an RME AES-32. I did a lot of experimenting with this and my Weiss AFI1. What I found was that the RME sounds similar to the Weiss when the RME AES signal voltage is set to 'Consumer'. At this setting, the AES signal is around 2V (similar to the Weiss).

When I was looking into all of this, I was totally flabbergasted by the importantance of getting this AES voltage right. But having liaised with a couple of very knowledgeable people (including the designer of my ADC/DAC), it started to make more sense...

Just check which AES voltage your Lavry is happiest with; 'Professional' (~5V) or 'Consumer' (~2V). My ADC/DAC likes 5V, but I suspect your Lavry will be happier with 2V.

Cheers,
Mani.

I’ll begin by apologising for this post from the outset – it’s probably of absolutely no interest to any of you...

Speed, speed, speed. This is what people seem to be saying really matters. OK, I’ll buy into this. So, I’ve been looking into an ultra-fast and reasonably powerful amplifier to drive my Quad electrostatics. ‘Spectral’ amplifiers seem an obvious choice, to try at least.

So, I called a Spectral dealer in the UK called Steven Harper (of ‘The Audio Consultants’) to have a chat. His first question was, “What are you using as a source?” This kind of surprised me because I would have thought that the obvious first question to ask when you’re considering an amplifier is, “What are your speakers?”... but there you go. I explained that I have a PC/DAC as my main source and before I could go on to give any details, he scowled at me. I then had a 30 minute lecture (really, a one-way lecture) on how a CD played back on a £20K Spectral or a £10K Nagra CD player (both of which he sells) will beat any other digital source. During these 30 minutes, I listened as politely as I could muster while he recounted all the occasions where he had demonstrated the superiority of these CD players to his customers over their “terrible-sounding USB DACs”, and where he also made some pretty dodgy statements about digital audio in general (he obviously didn’t know what ‘bit depth’ and ‘sample rate’ meant). I did actually agree with some of the points he made - he believed that the best sounding labels on CD are ECM and Reference Recordings – I think they sound great too.

So, 30 minutes into the ‘conversation’, once I could get a word in, I mentioned that my PC wasn’t actually connected to my DAC via USB. He was taken aback. “So how else can it be connected?” he asked. After I’d explained how my PC and DAC were connected, the ‘conversation’ then went on to why I would want to use a PC/DAC anyway, as opposed to a good CD player. I mentioned that one of the advantages is that I can play back hires material. As an example, I cited the Reference Recording 24/176.4 hires files. According to RR, these are direct copies of the digital masters which have been derived by digitising the analogue master tapes. But he believed that his CDs had a higher native resolution that my 24/176.4 files. His reasoning was that these hires files contain higher jitter than the CDs because jitter is introduced when files are downloaded from online (???). I mentioned that my files were not actually downloaded at all, but were copies of the digital masters put onto DVD-Rs and sent to me via the post (I don’t think he believed me). In a really condescending manner, he implied that I was mistaken if I thought that my PC/DAC combo playing any files could even come close to his Spectral CD player. At this point, I pretty much had enough and let him know that actually my DAC was an ADC also, and actually the very machine that was used to create the RR CDs that he thinks sound so wonderful. Oh and that the £20K Spectral CD player’s output stage is based on the DAC section of my machine.

Anyway, it was 45 minutes into our ‘conversation’ by now and I’d had enough. I had called as a genuine buyer for an amp. True, I wasn’t going to buy the top-end Spectral amp, but the one that I was considering was still £10K! And rather than trying to understand what I was trying to achieve, he went off lecturing me about how cr*p computer audio is – something that he patently knows very little about. So, I said that I’d buy the Spectral amp from someone else and I put the phone down on him...

What a strange interaction.

Mani.

I'd like to retract this statement.

I didn't feel like working today and have spent the whole day reading (currently getting through 'Fooled by Randomness' by Nassim Taleb) and listening to music.

I've also been comparing amplifiers again. The main reason for this is that I've had a couple of offers for my Pass Aleph 4 power amp and X1 preamp (around a third of what I paid for them new 9-10 years ago). Before saying 'yes', I just wanted to make sure that I was doing the right thing. And boy am I glad I did! The Aleph 4 is MUCH better than the Hypex amp. The Hypex amp sounds ultra, ultra smooth... but pretty dead and boring in comparison to the Aleph. It also has much lower resolution - it sounds smeared in comparison. The Aleph is SO musical - it sings. Its top end is WAY more extended than the Hypex. But across the range, it's just better in every respect.

Indeed, I concure with everything that Pedal and Telstar have said - I'd now only recommend the Hypex modules for bass and not for full range duties.

I really don't know what happened when my friends were around a few weeks ago. We all agreed that the Hypex sounded better then. There must have been something seriously wrong with the way I set things up... that's all I can think of.


I’ve mentioned before that the Pass has a slew rate of 30 volts/microsecond – in Nelson Pass’s own words: “... which is about 30 times faster than the fastest signal you will ever see, and about 100 times faster than what you will be listening to.”

So how ‘fast’ is fast enough?

Mani.

Well, if that's the chip its using, then it's certainly 18 bit... and not 24 like the NOS1.

http://www.audiodesignguide.com/DacEnd/AD1865.pdf

Mani.

GO HOLLAND! Teach these Uruguayans that cheating doesn't pay.

Ghana deserved to be playing tonight...

Mani.

Yes, well done The Netherlands...

Mani.

Peter/Marcin,

You guys have just redefined 'off-topic' for me!

Marcin, good luck with your new 'computeraudiophile-like' endeavour... But as well as focusing on the absolute leading-edge in CA, I think there really is a market for helping 'regular' audiophiles enter into the world of computer audio. I know of many who are holding off for two main reasons:
1) they are infinitely knowledgeable about 'regular' audio but just feel 'inadequate' wrt to computer audio
2) they are waiting for more 'true' hi-rez material to appear - but as we know here, processes like AP can perform alchemy on 16/44.1 CD rips (perhaps AP will be considered the true audiophile 'Philosopher's Stone' in years to come)

Mani.

Well that was really the motivation for trying this in the first place. So, I didn't manage to test this.

But as I said, right now, I'm satisfied with my PC/RME/AES setup... SMPS 'n'all - I think Zalman must have done good job with the design of the TNN300 case and it's integrated silent SMPS.

Mani.

Yes, I received the 'PCIe to 4xPCI Expansion Box' from VirtuaVia a couple of weeks ago. It was a disaster!

Not only did my latency go to pot (I couldn't even play Adaptive with a buffer of 4096 samples!), but it made my PC very unstable also. I was regularly getting the blue ‘screen of death’. I installed the ‘ExpressBooster’ program that came supplied with the box, which just made things worse – my PC would not boot up at all. I had to boot in safe mode and uninstall the software.

In any event, as you've no doubt already have garnered from this thread, I'm satisfied that my RME card is performing well plugged directly into the PCI socket of the mobo.

Please learn from my mistake - even though I received a full refund for the box (€189), this episode has cost me >€100 in shipping costs. I strongly recommend anyone to AVOID this box. However, I commend VirtuaVia for providing good customer service and a 'no quibble' money back policy.

Mani.

Exactly.

My vinyl setup is:

Technics SP-10MkII on a solid metal plinth and mounted securely onto a supporting brick wall  (i.e. the most rigid support available)
SME 3009 ('pre-improved') arm
Denon 103 cartridge
Rotel RHQ-10 phono stage
Henry Matchbox HD single-ended phono to balanced XLR converter

This is not a particulary expensive vinyl setup, as far as they go. However, I know many vinyl aficionados who would claim that this is a very good setup. As I have already stated, 16/44.1 files that I've recorded from single-sided 45rpm vinyl on this setup trounce the equivalent CD rip.

Good luck with your recordings!

Mani.

I agree that it doesn't prove that my PC is necessarily optimally configured to play back 16/44.1 files through XX. But it does prove that my PC is optimally configured to play back 24/4fs files through XX. I mean, how could playback be any better than the analogue source from which the 24/4fs files were derived?

But I doubt the PC is strained any more when playing back 16/44.1 files than when playing 24/4fs files, even with QAP and/or HDCD - my understanding is that this is all done in pre-processing.

Of course, I totally concede that my analogue source, amp and speakers may not be of high enough quality to really hear nauanced differences. It is therefore here that I would now like to focus, rather than on the digital side of things. As I improve the analogue components, maybe I will start hearing deficiencies in the digital recording/playback chain...

Mani.

Do you have an AD/DA converter, or is it just a DAC? If it's the latter, you're not going to be able to do exactly what I did.

Mani.

Huh? When did I say, "Everything sounds the same?"

If I make a change to the AES voltage, to the AES cables or to buffers, the sound changes. It's taken me a while to find the 'sweet spot' and I probably wouldn't have found it if it were not for Keith Johnson's input. And here was the issue:

From the Model Two manual:
“The AES Ground Isolators should be connected to all AES digital signal inputs and outputs at the Model Two whenever they are in use.
The AES Ground Isolators consist of a number of turns of precision 110 Ohm balanced, shielded cable fed through multiple ferrite cores, each having a different selected permeability.”

So naturally, I have been using these AES Ground Isolators since I got the Model Two. But in his response to me, KJ said:

“... I find that sometimes a ferrite core on the interconnect wire or more drastic changes make improvements for that particular hookup. However things could be better or worse for a different one."

(The highlight is mine.) After reading this, I decided to try without these Ground Isolators (going against the strong recommendation in the manual)... and voila, I found that they were making things worse and not better. [EDIT: Having removed them, I found the 'sweet spot' by using an AES voltage of 5V and my 'cheap' Sommer Dsub-AES breakout cable.]

So what exactly is the same? Well:
1) the analogue source
2) the analogue source being fed through the Model Twos AD section and then internally to its DA section
3) the analogue source being fed through the Model Twos AD section then through an AES cable to the RME card, through the RMEs mixer, and then back down an AES cable to the Model Twos DA section
4) a 24/4fs recording of the analogue source being played back on XX

These four sound identical, all else being equal.

Mani.