Watts Up...?
Mar 18, 2022 at 6:56 AM Post #3,271 of 3,621

AndrewOld

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On Friday 4th March my son Daniel asked me whether I wanted to help record a practice concert, happening on the next day, with his music theory teacher. He was a bit vague on the details (like when the actual concert was), but I thought this would be a great opportunity. Whenever you listen to a recording, one has no idea of the provenance of that recording - the sound of the performance, the acoustic, mikes, recording gear etc. How can we as audiophiles know how really transparent our gear is when we have a huge part of the chain outside of our experience? So I jumped at the chance, as it meant that I could evaluate the whole chain. It also meant that we could learn about the issues of recording orchestras - something my son (who is studying music production) hadn't done before. I thought that this would be just a bunch of kids learning music - but it turned out to be a specially commissioned piece with a capable amateur orchestra. And this was just a practice session, and Alida Watters (Daniel's music teacher) wanted us to record the full concert on Saturday 19th March at Gorseinon South Wales.

Readers of this blog will be aware of that some time ago I bought an AEA R88 stereo ribbon mike for doing Blumlein recordings. This is a very pure technique, as you simply use two mikes with a figure of 8 pattern - this means off axis sounds the mike has no output, on axis full output. You can read about it here. The technique has huge potential for transparency, as no mixing EQ or editing is involved - in our case the mikes go straight into the Focusrite Scarlett 18i8 ADC connected to a laptop which bit-perfectly records the digital data from the ADC. Monitoring is via USB to a Hugo 2 with DCA Stealths.

I must admit to having some trepidation about this. We have never recorded anything like this before - would we make a mess of it? How well would the Blumlein technique work in practice? On paper it's the most accurate and transparent technique available - but I don't have a single recording where I know that the technique is used. Most recordings are multi mics, with huge mixing consoles (and if you have ever heard the OP of a mixing desk direct it's not good too). The simplest technique used is the Decca tree, but that uses a simple mixer as it uses 3 mics. So why isn't Blumlein used more often? Perhaps it doesn't work too well...

Anyway, we set up the system (all battery powered to eliminate mains RF noise), and started monitoring. I used Hugo 2 and DCA Stealth, with my hands clamped hard against the ear cups; matched the volume, and compared the headphone sound to the actual sound, with me listening directly under the ribbon mics. First surprise - digital monitoring sounded very close to the actual sound. We took 5 takes, and subtlety adjusted the positioning, such that listening direct and with headphones gave no difference at all in the precision of lateral (left to right) placement - no detectable difference in angle, or how focussed the instrument was placed. That was a pretty stunning result.

20220305_153950.jpg

Mic position

20220305_154019.jpg

Daniel in the foreground running the recording. Note the player on the left with his hood up - the noise from the heating system meant they had to practice in the cold!

But when we got home we checked the takes, and realised that listening at your leisure gave very different results to listening live. Without stress, ones sensitivity improves dramatically; also, you can go back and forth and compare the different takes much more thoroughly. And it turned out that the first take (take 1), albeit not ideal, was the best for depth; the other takes had more accurate lateral placement, with take 1 being slightly too wide. We figured out the reason for this - subsequent takes had the rear lobe of the mic pointing more to the ceiling, thus suppressing the perception of depth. For the actual concert (which will be joined by full wind and 4 soloists) Daniel will adjust the mic position from these lessons learned and hopefully we will get the best hybrid of the takes - that is good depth and accurate lateral placement.

I decided to publish take 1. Thanks to @Kentajalli for hosting this. If you listen on headphones use cross-feed set to max. Loudspeakers will be fine with no cross-feed.

So how did the takes sound compared to the live performance? In short I was pleasantly surprised as to how close it came, but with some extremely important differences:

1. The tonal balance - the recordings played back via speakers (something I can't talk about plus TT2 driving B and W 803D3) is quite a lot warmer than reality. Played back via (something I can't talk about and Dave with DCA Stealth) is still considerably warmer than reality, but more accurate in tonal balance than the loudspeakers. Having said that, the Church used for the tests is quite bright - most audiophiles would find it way too bright (but then many audiophiles don't listen to live non amplified music either and some audiophiles wouldn't know good sound if they were hit over the head with it as they listen by brand or wallet). Via the Stealth the balance is to my taste; but it exposes the real reason I went to the trouble of doing the lossless (or completely transparent) EQ on Mojo 2 - so that the system can go onto the ADC. Gentle EQ is appropriate (so long as it's completely transparent) for transducer and acoustic problems.

A quick word here about the Stealth - this is a headphone that impresses me the more I hear it. In particular the HF - as it has a very impressive purity and lack of resonances, and although the overall balance of the recording is warmer, it's nonetheless very accurate.

2. Depth. So on the live versus headphone digital feed by far the biggest change was the suppression of instrument placement depth. So the lead Cello is around 5 metres away from the mic; but listening on the headphones it immediately dropped by about 50%, to say 2.5m impression of depth. Listening to the takes again back at home reinforced that impression - Hugo 2/Stealth around 50%, x Scaler/Dave gave better impression around 66% of the depth (perhaps better but no more than 75%). On my 803, we felt it was pretty accurate sitting in the listening position - but of course this is artificially adding 2m anyway (listening position to loudspeakers).

3. Softness of transients. All the takes had a softening to transients - you can't perceive the starting of notes as accurately as live. This was apparent with live against headphones, and listening back home.

4. Timbre variation. Noting that everything is generally warmer than reality, there was one exception, the piano on the hard right side. This was very warm live (soft and warm like many English pianos and when used and the lid was down) but on the takes was brighter than reality, indicating that timbre variation is being suppressed.

5. Instrument separation and focus. This was pretty good, but not as good as live - it's not so easy to follow the lead violin when the cello plays.

Now the above deficiencies were entirely expected and I am convinced due to the ADC. Depth will be vastly improved by using the pulse array noise shapers, as it will resolve small signals much more accurately. I also know that aliasing - as I have been doing lots of listening tests recently - is a huge problem, and it directly affects the perception of the starting and stopping of transients. To stop this, you need to completely eliminate any trace of aliasing - to ridiculously small levels - and ADCs today have huge levels of aliasing. So I am confident that this deficiency can be overcome, or at least markedly improved upon. And careful readers will know from my posts that timbre variation and instrument separation and focus is down to noise floor modulation - something for which modern ADCs have large amounts of.

The experience also taught me that the Blumlein technique doesn't have any fundamental flaws. I was worried that it might over emphasise reverb - but the reverb you hear on the take is exactly as per the live acoustic, as the reverb in the church was a little dry compared to a concert hall. The technique in terms of lateral imagery (left to right) is nigh on perfect; placement of instruments laterally is the same as live whilst using the Stealth or the 803 D3. Moreover, instrument separation and focus, albeit not as good as live, I think is better than any recording I have. I wish all classical recordings used this simple technique.

I was also left with the impression how good the transducers (the R88, Stealth and 803) are - and also how good Hugo 2 is (and if I had used Mojo 2 I no doubt would be saying the same) compared to the live music. It was very much closer than I expected.

But my big and overwhelming excitement was hearing the deficiencies, and realising that these problems can, I think, be solved with the upcoming pulse array ADC. It's given me a huge stimulus to get the technical difficulties with the project overcome.

Just think - being able to close the gap from live non amplified sound to reproduced is a very exciting prospect indeed.
You might be interested in this book, “Classical Recording A Practical Guide in the Decca Tradition By Caroline Haigh, John Dunkerley, Mark Rogers”

https://www.routledge.com/Classical...RTB7gEo8PbkMGD93nzLTMOr9tPnhUvC4aAiALEALw_wcB

Classical Recording: A Practical Guide in the Decca Tradition is the authoritative guide to all aspects of recording acoustic classical music. Offering detailed descriptions, diagrams, and photographs of fundamental recording techniques such as the Decca tree, this book offers a comprehensive overview of the essential skills involved in successfully producing a classical recording. Written by engineers with years of experience working for Decca and Abbey Road Studios and as freelancers, Classical Recording equips the student, the interested amateur, and the practising professional with the required knowledge and confidence to tackle everything from solo piano to opera.”
 
Mar 18, 2022 at 8:31 AM Post #3,272 of 3,621

Christer

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In January, I was lucky enough to sit front of stalls at The Bridgewater Hall, Manchester for Mahler 3. Alice Coote singing directly down at me. A few days later the BBC broadcast the concert but the difference was night and day. I'm sure the main difference came from the position of the microphones suspended from on high. Via the radio, I was listening from above and not below. It was far less intimate.
I have had similar experiences many times to the one you describe .But apart from the very few ones I made myself informally with my Sony DAT and two spaced omnis or figure of 8 miking into my digital camera from a good seat in the hall, at all the actual professional recordings sessions I have been present at, official mics have always been imho a bit too high above the musicians to capture the sound as one would hear it from a good midstalls seat.
Judging from the 2 pics Rob just posted he seems to have put his mic a bit too high too.
And in too many cases of actual sessions,there has also been a veritable forest of mics spread out among the orchestra players on stage.
"Only for backup and if really needed for final mastering" is the answer I have mostly been given.
And with mch recordings for SACD or mch downloads release two mics are simply not enough for mch speaker playback.
Unfortunately my old Sony DAT is probably irreparably broken. I left it with batteries in for too long.The good thing about it compared to Rob´s Hugos and Mojos was that it ran on ordinary AA batteries before they started leaking.But I am getting interested in buying one of the newer 32bits capable portable recorders and start recording both nature sounds again and maybe some of the promising budding young musicians at the Vadstena Piano and Opera Academy not far from where I live.
Regarding Rob´s first?Church recording having listened to it more than once now I am also a bit surprised how dry it sounds via my speakers.
Nice string timbre , both bowed and plucked. With some to my ears not absolutely perfect playing included in the snippet.
But I do not hear much of any Church acoustic?
Maybe I need both a Dave and an Mscaler X?

It reminds me a bit of how Morten Lindberg of 2L recorded the Trondheim Soloists in Selbu church in DXD some years ago .
He captured them very much as being up on stage with them. Intentionally quite intimate and dry. I actually liked the richer more reverberant sound from the Organ Balcony best of all, although it was very exciting to be right in the middle of it all with my camera during Grieg´s "Sarabande".
And it is still one of my reference recordings of how a Chamber Strings Orchestra actually sounds close up.
Maybe Rob and Davina will become a challenge to that?



Cheers CC
 
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Mar 20, 2022 at 2:00 AM Post #3,273 of 3,621
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A quick word here about the Stealth - this is a headphone that impresses me the more I hear it. In particular the HF - as it has a very impressive purity and lack of resonances, and although the overall balance of the recording is warmer, it's nonetheless very accurate
Glad to know that my prediction was right. I was just watching your presentation at CanJam, which MidFi Guy uploaded to Youtube. Just prior, I had been watching Dan Clark's one, which covers a lot of related ground.
 
Mar 20, 2022 at 9:49 AM Post #3,274 of 3,621

ecwl

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Glad to know that my prediction was right. I was just watching your presentation at CanJam, which MidFi Guy uploaded to Youtube. Just prior, I had been watching Dan Clark's one, which covers a lot of related ground.
Thanks for sharing the MidFi Guy YouTube video. What I learnt was that:
1) Rob Watts may have found a limit for audibility of noise floor modulation, perhaps from his ADC research which I presume he’ll share once the DAVINA ADC is ready
2) Rob Watts will talk about his WTA filter algorithm upgrade next year which may mean that ”the thing he can’t talk about”, which we presume to be the Choral M-Scaler, may not come out until the very end of the year or maybe until 2023
3) 64-bit floating point DSP actually adds noise floor modulation (in addition to have potential small signal phase & amplitude accuracy issues)
In the mean time, I’m more tempted to buy the Mojo2 even though I don’t need it.
Time to listen to Dan Clark talk about Stealth on MidFi Guy. Another product I’m tempted to buy buy don’t need.
 
Mar 25, 2022 at 4:45 AM Post #3,275 of 3,621

hmartin

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After using the Mojo 2 for some time I must say that it is amazing to be able to bring such high performance in such a small size. Love addition of crossfeed and the extended volumerange.

Now to a question, getting rid of the passive crossover in speakers must be one of the biggest improvements we have to look forward to. Considering the Mojo 2 DSP feature this now seems within reach? But it seems to me that it would not add much cost to e.g. a mscaler to include a digital crossover? The upsampling to 768 would be the same, the compute for the DSP is pretty cheap(?) so the mayor cost is adding 1or 2 extra dual bnc outputs?
 
Mar 25, 2022 at 6:38 AM Post #3,276 of 3,621

Kentajalli

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Now to a question, getting rid of the passive crossover in speakers must be one of the biggest improvements we have to look forward to. C
I went down that route with analogue active speakers a while ago. I have also auditioned newer incarnations from respectable companies recently.
On paper, it should improve things, but subjectively, I have not heard any real improvements with my own ears.
 
Mar 25, 2022 at 7:07 AM Post #3,277 of 3,621

Rob Watts

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After using the Mojo 2 for some time I must say that it is amazing to be able to bring such high performance in such a small size. Love addition of crossfeed and the extended volumerange.

Now to a question, getting rid of the passive crossover in speakers must be one of the biggest improvements we have to look forward to. Considering the Mojo 2 DSP feature this now seems within reach? But it seems to me that it would not add much cost to e.g. a mscaler to include a digital crossover? The upsampling to 768 would be the same, the compute for the DSP is pretty cheap(?) so the mayor cost is adding 1or 2 extra dual bnc outputs?
Agreed - I think getting rid of passive crossovers should provide us with huge potential improvements in SQ.

It's very much on my to do list, but it's something that would have to be done in conjunction with a loudspeaker company. Once the ADC and DX amps are done...
 
Mar 25, 2022 at 7:37 AM Post #3,278 of 3,621

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On the same note regarding removing passive crossovers, ATC loudspeakers offer Active version without passive crossovers. Though still AB amps.
btw, waiting for my 19A to arrive sometime this spring. Will use them directly from TT2/HMS. Wondering how they will integrate into Chord transparency and musicality.
 
Mar 25, 2022 at 7:48 AM Post #3,279 of 3,621

Triode User

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On the same note regarding removing passive crossovers, ATC loudspeakers offer Active version without passive crossovers. Though still AB amps.
btw, waiting for my 19A to arrive sometime this spring. Will use them directly from TT2/HMS. Wondering how they will integrate into Chord transparency and musicality.
From personal experience and to my ears the ATC actives integrate very well with the Chord Dacs connecting them directly and using the Chord DAC for volume control. I used to use the TT2 connected to ATC40 actives and now I use the Dave connected to ATC150 actives. Of course the ATC actives have XLR input and so I use the XLR outputs from the Dacs.
 
Mar 25, 2022 at 7:48 AM Post #3,280 of 3,621

hmartin

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On the same note regarding removing passive crossovers, ATC loudspeakers offer Active version without passive crossovers. Though still AB amps.
btw, waiting for my 19A to arrive sometime this spring. Will use them directly from TT2/HMS. Wondering how they will integrate into Chord transparency and musicality.
Big fan of Atc speakers, the newer models with Atc tweeters are fantastic.

Problem is switching to active speakers when already invested in amps etc. But starting fresh active Atcs is perhaps best value today imho.
 
Mar 25, 2022 at 7:50 AM Post #3,281 of 3,621

Vyyy

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From personal experience and to my ears the ATC actives integrate very well with the Chord Dacs connecting them directly and using the Chord DAC for volume control. I used to use the TT2 connected to ATC40 actives and now I use the Dave connected to ATC150 actives. Of course the ATC actives have XLR input and so I use the XLR outputs from the Dacs.
Yes i will connect straight from TT2 with Furutech CF-601M/F and FA-αS22 cable.
 
Mar 25, 2022 at 7:52 AM Post #3,282 of 3,621

uzi2

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Agreed - I think getting rid of passive crossovers should provide us with huge potential improvements in SQ.

It's very much on my to do list, but it's something that would have to be done in conjunction with a loudspeaker company. Once the ADC and DX amps are done...
There is a very good one just a short distance down river from Chord HQ
 
Mar 25, 2022 at 7:56 AM Post #3,283 of 3,621

griff500

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Big fan of Atc speakers, the newer models with Atc tweeters are fantastic.

Problem is switching to active speakers when already invested in amps etc. But starting fresh active Atcs is perhaps best value today imho.
That's what I did and I've been very pleased with my SCM40A. They would only be replaced by models further up the range.
 
Mar 25, 2022 at 11:36 AM Post #3,284 of 3,621

Kentajalli

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I heard Kudos Titan 808 at London Hi End show a few years ago, active amplification by Linn Exact system.
If memory serves right, the Exact system, is a programmable digital crossover / amplifier system. An SD card is used to program the crossovers for different speakers.
So the same crossover/amplifiers can work with various speakers by changing software. But RW is correct, they have to work in conjunction with speaker company.
A year later, I heard the same speakers with Exposure amplifiers, and they were doing a crude A/B against passive!
- The Linn-Kudos sounded superb! but no better than some passive speakers from B&W or Magico.
- Kudos-Exposure sounded very good too, but I preferred the Passive version! somehow the Active left something on the table.
The potential is there, absolutely, on paper.
Meridian has also been making active speakers, very successfully.
In 1989, I made my own!
Using a five-sided column design, two 8" bass units, a Kef B110 and Morel tweeters.
Amplification was a mofified Meridian 105 mono poweramp for Bass drivers, and a 103D stereo for midrange and tweeter.
Crossover was acrude design of mine using discreet circuitry to split the input from my pre-amp into three bands!
I had it for 10 years, before giving it away to a very good friend. They still work to this day.
Sounded very good too.

DSCF0690.jpg
It weight a ton! three 200VA transformers in the base of that column, many many capacitors! linear PSU's for input sections of the amps and the crossover.
You can see the Meridian Alu boxes in front at the bottom.
 
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Mar 25, 2022 at 12:56 PM Post #3,285 of 3,621

feddar

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@Rob Watts,

On the TT2, is there any harm with using RCA for one set of speakers and the 1/4” headphone plug for another set, and do A/B testing by plugging and unplugging the 1/4”. I do this with my open headphones, and I assume that is not an issue. Please correct me if I am wrong.

Thanks again!
 

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