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Multi-Way Conventional loudspeakers with crossovers

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Old 9th August 2017, 12:54 AM   #14621
Pano is offline Pano  United States
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The now discontinued P.Audio 18" coax made for an efficient open baffle speaker, on the right size baffle. It had enough grunt in the bottom that even trading away the open baffle rising response left it in the 90s @ 2.83V
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Old 9th August 2017, 04:16 AM   #14622
Kindhornman is offline Kindhornman  United States
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I have to say that the open baffle concept just goes against everything I would hold true from a bass reflex or sealed box. Talking about critical placement, that is the only way you can create any semblance of real bass from an open back. I would expect some of the worst comb filter effects from any open backed cabinet in the bass and mid-bass regions.
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Old 9th August 2017, 04:51 AM   #14623
Pano is offline Pano  United States
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And yet, they can work beautifully. Yes, they do need to be away from the walls, but otherwise placement isn't too critical. The main trade off is loss of bass efficiency.
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Old 11th August 2017, 02:21 AM   #14624
Pano is offline Pano  United States
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John's compression test got me to thinking about the energy in different musical registers. There are some graphs around the web, but I decided to DIY mine. You might find them interesting.
Spectrum of Musical Genres
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Old 11th August 2017, 11:14 AM   #14625
marco_gea is offline marco_gea  Italy
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Default R2R DAC > Class A amp > BTA-like speakers

This post is mostly directed to Lynn Olson (the originator of this thread)...

I have gradually transitioned towards a system that falls in line with many of the recommendations provided by Lynn over the years.

At present, the backbone of my listening chain (I will intentionally just mention the core technologies employed and withold the brand names for the time being) is composed of :

1) A network player reading a mix of 16/44, 24/88, 24/96, 24/192 FLAC and 2.8M & 5.6M DSD files from a NAS drive.
This device uses a PCM1795 Delta-Sigma DAC chip which switches to a "direct DSD" mode when decoding DSD files.

2) An conventional single-ended analog solid state preamp and a push-pull MOSFET power amp that is biased heavily into class A (up to 45W per channel into 8 Ohms, beyond which it transitions to class AB and tops out at 100W per channel into 8 Ohms)

3) A "Beyond-the-Ariel" inspired loudspeaker system consisting of:
- a low-mechanical loss and medium-high efficiency 15" hybrid cone woofer,
housed in an overdamped bass-reflex box made of thick baltic birch multiply,
- a large-format compression driver with Beryllium diaphragm,
- a ~300Hz hypex radial horn, carved out of a solid block of baltic birch plywood and with a throat adapter that perfectly matches the geometry and exit angle of the driver's internal throat and smoothly transitions to the radial portion of the horn,
- a horn-loaded ring radiator supertweeter used to improve dispersion above 6kHz,
- a passive crossover that ensures almost perfect phase tracking between the woofer and compression driver over a wide range of frequencies around the first crossover point of 600Hz.

Given that while putting together this system, each step along the way has been an improvement, I have come to hold in higher and higher regard Lynn's opinions.

And having read his musings on the virtues of R2R multi-bit DACs, I am now intrigued by the idea of testing this out for myself, by inserting one such DAC in between 1) and 2) above (obviously, this would be for the reproduction of the PCM FLACs only; the network player's internal PCM1795 would still be called upon to play DSD files).

The only problem with this is that there are VERY FEW multi-bit DACs on the market today (MSB Technology, AMR, Aqua, ...?) and most of them are very expensive indeed.

Others are less expensive (Schiit, Audio G-D, Soekris, ...?), but somehow I am a little sceptical about them (the top-of-the-line Schiit unit, for example, was reviewed by Stereophile, and the measurements don't look like anything to write home about...).

Then, browsing the internet, I have also come across one recently-discontinued DAC that can still be found new in Japan: the RATOC Audio Lab RAL-24192DM1.
This is intriguing to me because it is a dual mono unit that uses two PCM1704 24-bit chips that are highly regarded by Lynn, it looks like it is very cleanly and neatly put together, and it does not cost the Earth.
It also received a rave review in a German Hi-Fi magazine (for what it's worth...)
I'm currently debating whether to pull the trigger or not...

And of course, Lynn: any further thoughts you might have to share would be greatly appreciated!

Cheers,
Marco

Last edited by marco_gea; 11th August 2017 at 11:16 AM.
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Old 11th August 2017, 01:55 PM   #14626
marco_gea is offline marco_gea  Italy
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Quote:
Originally Posted by marco_gea View Post

And of course, Lynn: any further thoughts you might have to share would be greatly appreciated!
In particular, what do you make of these quotes?

"RAL-24192DM1 doesn't use DF1704 8 x Oversampling and Digital Filter chip. It's Internal firmware control PCM1704 directly and bring out pure and natural sound from the DAC"

and

"RAL-24192DM1 doesn't use DIR(Digital Interface Receiver). RAL-24192DM1 includes software S/PDIF decoder, End Point(memory buffer) for 192 Frames and Timing/Control signal generator for Multi-bit DAC(PCM1704).
The timing/Control signal generator circuit is fully driven by dedicated two independent X-Tal Oscillator modules (24.576MHz and 22.5792MHz). This circuit provides low jitter Bit-Clock and it drives D/A converter accurately. "

Thank you in advance, and sorry everyone for the slightly OT tangent.
Marco
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Old 11th August 2017, 08:42 PM   #14627
Globulator is offline Globulator  United Kingdom
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Quote:
Originally Posted by marco_gea View Post
And having read his [URL="http://www.positive-feedback.com/Issue65/dac.htm"]musings
Ooh! I hadn't read that, thanks for linking!

I've been arguing for years that short transients are not helped by dither and that no one actually uses 44.1k as everything decent up-samples it: Very refreshing to find a man I hugely respect (from his other writings on NutShell HiFi) also pointing out the obvious issues too.

At 88.2 the dither works twice as fast, the steps are half the size and the frequency way above the 22.05kHz that's theoretically there. It would be rude not to..

I tend to play my music from a PC or Tablet into a USB converter capable of 88.2/24 (which are around for 22), and configure my app (see sig.) to output at 88.2/24, set the PC to full volume and to drive the USB at 88.2/24 and then use the optical to drive a DAC (Behringer Ultracurve with RCA's wired directly to the DAC outputs). This can also EQ the room for me too..

I also have a Behringer Ultramatch which can also see what rate/depth is incoming but also experiment with rate/bit conversions too.

So the thread relevant point I'm slowly heading toward is that you can get very nice digital 2-3 way digital crossovers that will play with that rate/depth and feed the results off to separate driver specific DACs and amps to eliminate the crossovers, something I wouldn't be happy doing at 16bit purely down to the level issues alone.
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Old 12th August 2017, 11:34 AM   #14628
Lynn Olson is offline Lynn Olson  United States
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Well, the Ratoc DAC looks interesting; my "other" R2R Dac is from Audio-GD in Hong Kong and features the PCM-1704. My primary DAC is a 15-year-old Monarchy that uses the long-discontinued PCM-63K and a discrete all-tube analog signal path.

The other DAC I've auditioned in my system that sounded pretty impressive, maybe even better than the Monarchy, was Gary Dahl's Canadian-made exaSound DAC. For reasons that aren't clear to me, the exaSound doesn't sound like other DACs that use the ESS converters, so they must be doing something different. At any rate, it directly drove the Karna amplifiers in balanced mode with no trouble.

A few pages back, I mentioned that the crossovers for the Ariels feature sets of DPDT switches that select between a Marantz home-theater amplifier (MA8003) and the pair of Karna amplifiers. The grounds, as well as the signal, are switched, so there is never any ground connection between the entirely separate HT system and the all-triode, zero-feedback 2-channel system. The quick switchover between the Marantz HT and the exotic triode system keeps things honest; the specs of the THX-certified HT system are pretty decent, and Marantz has dialled-in the subjective sound of their electronics so they don't sound as shrill and edgy as the majority of HT equipment. I could describe them as "smooth" and easy-to-listen-to, and not a bad choice for folks who don't care for the hassles of vacuum tubes, but don't care for the edge and grain of many transistor amps.

If I ever upgraded the 5-channel system, I'd pick the Bryston multichannel amp, which sounded really good a few years back at the RMAF show. At any rate, I have two completely different systems to drive the Ariels, and both sound pretty decent. One thing I have discovered is that as efficiency goes up, it acts like a magnifying lens on the rest of the signal chain, whether solid-state or vacuum-tube.

Last edited by Lynn Olson; 12th August 2017 at 11:50 AM.
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Old 14th August 2017, 01:01 AM   #14629
jpak is offline jpak  United States
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Quote:
Originally Posted by marco_gea View Post

Others are less expensive (Schiit, Audio G-D, Soekris, ...?), but somehow I am a little sceptical about them (the top-of-the-line Schiit unit, for example, was reviewed by Stereophile, and the measurements don't look like anything to write home about...).
I owned one, sold it and bought another one

Hard to describe the sound of it but I'll try- it was quite transparent with a bit of "something" that I can't quite explain that made me enjoy classical music more and want to explore more performances than simply think about how good the digital I was listening to was. I also noticed myself listening to historical recordings that sound harsh from 78 rpm surface noise at a comfortable volume, whereas before I would turn down the volume. I'd encourage anyone interested to have a listen to it or the multibit Gungnir, which I have not heard.

I sold it because I initially thought it was overpriced and I really didn't like that the manufacturer recommends leaving it on all the time due to the DACs used since I experienced occasional power outages and was worried about it getting damaged. It was afterwards that I realized I missed the sound of it.
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Old 14th August 2017, 02:51 AM   #14630
gedlee is offline gedlee  United States
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reviewed by Stereophile, and the measurements don't look like anything to write home about...
Seriously!!! You expected a correlation between objective and subjective assessments beyond money?
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