There is a 6moons review of the intone USB isolator. The reviewer asks himself:


Blood at normal temperatures in this place !

regards, Coen

Hi Peter,

Even in 2017 you cannot treat production has an afterthought. That second industrial revolution still needs a lots of kicking in.

If green is better so be it. Looking forward to the upgrade!

regards, Coen

Looks great Peter,

Unfortunately no sexy white ones so we will have to keep the lid on the NOS !

Let's put PCBWay first!

regards, Coen

I've not yet heard them, only watched the video. There is some Youtube material of audioshow demos that could give a faint impression. I've subscribed to a Beolab90 tour demo maillist because I wanted to hear the merits for myself.

To be frank I'm not that surprised by your findings of the demo, theory is one, execution is two. I became worried at the class-d amplifiers part. They are able to make everything sound like MP3 (maybe that's why they choose to demo with MP3).
And the demo itself? A missed opportunity? Different target audience? No room treatment eh?

Though I have great respect for the research and design effort, this never would be a speaker for me. I'm more of a "less is more" kind of guy. This worked for me all the time.

regards, Coen

No way!

Please be a room treatment evangelist!

I've my share of room problems too. I've never being able to give left and right completely the same balance and have great stereo at the same time.

The merits of room treatments are well advertised, but you rarely encounter a room that has been "treated" for good audio (save for some voodoo patches or curtains on the wall -no wife!-). I never followed up to my plans to make a diffusor, I guess electronics are much more sexy to me.

In the end the acoustical room correctors make a lot of sense in a stereo setting where we aim for identical response. As I learned from the better part of the video speaker placement has a large influence in the sub 300Hz area. No way that is going to be the same for each speaker in a real untreated room.

regards, Coen

You can promote a speaker without marginalizing your audience.

In this video the new Beolab 90 fully active speakers technicalities are explained:

https://youtu.be/yC0hjRHCYs0

This speaker is designed in such a way that it is able to manipulate the directivity. The implications of directivity for the perception of location are mentioned as well as the link with the work environment of the sound engineers.

It is a speaker born out of passion for audio and thoroughness. Interesting material and imho relevant results are presented since we all listen to a stereo system and share the objectives.

regards, Coen



 

Agree, I would not expect something else. Standardized training of "ears" is a very interesting concept. Is it possible at all?

Good sound (if such a thing exists) is a pretty tough subject to capture scientifically. And if you were able to capture it, what would that mean in an "average" consumer setting where looks, practicality and price are more important? Ironically the very group that chases the same goal are the despised (untrained) audio fanatics. 

Blind testing is in my opinion somewhat handicapped though it may lead to a wonderful result. Ever tried to eat delicious gourmet food blindfolded or nice food that was purposely colored in an unnatural tint? The same food actually tastes different has scientific research shown.

regards, Coen

No, not at all. This is about my opinion on the content of the video and I'd be gladly confronted with insights that dispute it! The "you/your" should be taken as part of the expression, not addressing a specific person or group.
 
I got triggered into reacting to this thread solely because of the video (actually about the half i've seen) VJ shared here. The interpretations presented in this part were in my view at least disputable if not of low relevance. Please note that I have no problems with the scientific approach at all, but i object to the lack of prudence wrt to the interpretation of the results.

Now, I probably missed the more interesting parts lets spend some time on the second half!

regards, Coen

Pff.

Started with the video too. I was annoyed by the slightly arrogant attitude of this speaker. Listening to his story it seemed that audiophile/reviewer bashing was the key motive and perspective on the interpretation of his graphs. I could bear it only to halfway, but already the first few results tell a different story to me.

“ double blind tests are the best way to establish scientifically viable results”. This is one big can of worms. The discerning ability of the test subjects is also under test, so conclusions can only be drawn in a presupposed context. Stereophile’s lovely Michael Fremer once had a 100% correct score in blindly discerning different audio components and was excluded from the test results as a “statistical insignificance”. What are you trying to prove or learn by doing that, that MF isn't a representative person or that differences cannot be heard (-by untrained ears-)? This is as unscientific as it gets. Personally I know my system so well I can hear any change immediately, but I can guess stuff at best with someone else’s system.

“The more channels you add the less people are able to tell te difference, that’s why I use mono”. That points to a serious flaw in your testing methods dude. It also imposes serious limitations on the scope and usability of the tests. What are you trying to learn?

“People are biassed by a visual preference”. Like hell they are. The graphs shown also indicate that the test subjects can reliably discern nicely build sh*t from the real thing when looking at it while they listen. They appreciate good sounding and good-looking good stuff better. That doesn’t mean that it is irrelevant, its another limitation on your scope. It is well known that our senses work together in creating an experience along with our expectations of it. The cooperation makes the experience more intense, that’s why the experience of a live concert can never be reproduced by audio alone. That said, we may be able to get very close to recreating the audio part of it.
Imho reproduced audio is an experience in itself and the visual aesthetic of the gear and expectations of the listener are very much part of it.

Maybe it gets better later on….

regards, Coen

Nanotubes are allready done: http://www.vandenhul.com/cable-technologies/carbon-nano-tube-cnt

Looks very promising with electrons only.

This is allready extremely expensive..., oh and you have to put the ice in wich probably makes it even more so. I'm not an expert on particles but I'd say that all audio gear prefers electrons over protons for proper operation.

regards, Coen

Hi Peter,

In the background I expected no less from you !!!

Sounds like you have found the path from High Fidelity to Hyper Fidelity. A fascinating development. I appreciate the audio technicalities but does it also serve the musical immersion or are we in for a totally new experience?

cheers, Coen

Hi Peter

80 Euros for a Black Magic audio tweak with the suggested improvements that's quite a bargain these days. I salivate at the thought to hear the music that is hidden in the music so count me in immediately!
 
You sound pretty confident on this one. Is there really no need for the usual five day real-or-fake-cool-off period?

cheers, Coen

Hi Peter,

Thanks for the additions!

let me push yours a little further:

There is the efficiency of the loudspeaker that tells us about the amount sound pressure we get from 1 watt of power and the sensitivity that tells us about the amount of sound pressure we get from 2,83V RMS (which is of course 1 watt @ 8 Ohms, apply the math!). They are related via the impedance.

The sensitivity tells us about how much voltage the amplifier must deliver to play at a certain loudness, the efficiency purely how electrical power translates into sound pressure power.

Simply put the efficiency does not take the impedance into account, but the sensitivity does. A 100dB/watt efficient loudspeaker can have an impedance of any ohm. I have Philips 9710 AM that are 800ohms rated impedance and about 100dB efficiency, contrary to Peter's 8 ohm horns (2,83 volt) you will need a truckload of voltage (28,3V) to get a watt into them.

It takes some effort to estimate the amount of SPLs in your listening chair. As old fashioned dual channel listeners we have actually two amplifiers and two loudspeakers generating a signal. This potentially adds 3dB to the maximum attainable sound pressure.

Yet our chairs and couches are some meters from the speakers, we are usually not at the specificatied 1 meter away from them. Depending on the radiation pattern (directivity versus frequency) the sound pressure lowers with increasing distance from the loudspeaker. As a rule we may assume that the radiated surface increases with distance and as such decrease between 3 and 6dB every doubling away. So if the output is at 1m 100dB it is at 2m: 97-94 dB and at 4m 95 -88dB.  This suggests that we need more than 120dB (minus 3 ....) at the loudspeakers to get 120dB at our chairs.

But the room is not an infinite space, that is waves reflect on all boundaries: the floor, ceiling, sidewalls, but also tables closets etc. Especially the side and behind walls are acoustically close to the loudspeaker and as such are the reflections are significant. Well that is for those frequencies that the loudspeaker has a wide dispersion. Anyway a lot of energy is confined in and and interacts with the room. Signals with low directivity (lower notes) interact the most. This accounts for extra decibels for many frequencies.

In the end I do not think we need 120dB+ capable loudspeakers and amplifiers in our rooms. My 103dB Altec VOTT was intended to operate with a 15 watt amplifier. Originally they were designed for intelligible sound in a 400 seat movie theatre. I already got loudness complaints with my 2x0,8watt tube amp so in practice the "120 dB calculations"  do not really make sense.
Unlike the image industry there are little generally accepted and implemented references for sound. If this were the case we would be able listen to realistic sound levels, at least how they were recorded or intended by the engineer. Imho the 120dB case (a full-out orchestra: Mahler/ R. Strauss) can only apply with such a reference. In all other cases we would have changed the volume (=power) with the crescendo to something we can bear in our rooms.

regards, Coen

I think this thread is causing confusion, at least to me so hereunder an attempt to clarify my view on power a little.  

Peak sinus power and average RMS power have physical definitions.

Rated amplifier power is always rated at a certain (restive) impedance.

This has a lot of implications.

————— tutorial break “understanding power”—————

Delivered Power is defined as (Applied Voltage)x(Required Current).

The amount of current required for a certain applied voltage is determined by Ohm's law: Required Current (Ampere) = Applied Voltage (Volt) / Impedance (Ohm).
In loudspeakers this impedance is frequency dependent and as such has a "phase angle" that defines the lag between the current and applied voltage. This last complication is not needed to understand power delivery.

Say the impedance at a certain frequency is 8 ohm (no phase angle). If we have a signal that peaks at say 40 Volts than the required peak current would be 40V / 8Ohm = 5 Amperes, hence the required peak power would be 40Vx5Amp = 200 Watts.
A sinusoidal signal averages out on the 'Root of the Mean of the Squares' aka RMS value which is root(1/2) x Max voltage. At root(1/2) x Max voltage, the required average current current would be: root(1/2) xMax Voltage / impedance = root(1/2) x Required Current. The Average Power in RMS will now be the product of those two values hence root(1/2) x root (1/2) x peak Voltage x peak Current = 1/2 x  Peak Power (sinusoidal).

Halving the impedance to 4 ohms would double the required current for a given max voltage In the case of 40V this will be required peak current of 10 Amps in stead of 5 Amps, so double the power would be required by the loudspeaker :10Amps x 40V = 400 Watt peak. Doubling the impedance to ie 16 ohms wil consequently half the required power.

The above stated ‘phase angle” makes these precise calculations of the ‘current - voltage relation’ harder and more abstract, but what happens in practice is that there can be (far) more or (far) less current required by the loudspeaker (“load”) than the resistor would predict. In other words there may be more (or less) power required than in the resistor case. The amplifiers design has to be able to cope with this.

—————— end of tutorial break — — — — — — — -

Now a power amplifier specification measurement is usually performed with a resistive (no phase angle) load of a standardized value (to be able to compare). Mostly this will be 8 ohm. Power amplifiers however have two physical constraints that determine the maximum power that it can deliver into other loads than that value; ones that are greater or smaller than 8 ohms (and/or when the phase angle requires more or less current).
One is the maximum available voltage, the other the maximum available current.

Typically transistor power amplifiers operate at voltages that are close to the voltage that is required for the 8 ohm power specification. Our 100W RMS (hence 200W sinus peak into 8 ohms) amplifier wil likely operate at 50V-60V tension. This causes an available power reduction for a 16ohm load (2,5Amp needed for 40Volts or 100W peak or 50W RMS), yet the amplifier may be able to supply the 10 amps necessary for a 4 ohm load and as such provide more power when more amps are needed. Eventually the amplifiers power supply is not able to provide any more amps before blowing the fuse or significantly degrading the supply tension.
So this amp’s real maximum delivered power will be determined by how much current it is able to supply for the maximum voltage (about 40 V). This can be much more than the rated 100Watt.

 Amplifiers with a typical current constraint are OTL designs. The tubes operate at very high voltages (150-200V), but cannot source more than the tubes allow for the 8 ohm per specification (like 1 amp per tube max). That is that a 100Watt RMS (40V, 5 Amps at 8 ohm) rated OTL amp will not be able to deliver the 10 Amps required for 4 ohms, but it is able to deliver 5 Amps into 16 ohm. That is 5 amps at 80 Volt or 400Watt peak or 200Watt RMS. This amplifier real maximum power is limited by how much voltage it is able to generate for a 5 amp load. Also this can be much more than the rated 100Watt.

Usually -Single Ended- Tube amplifiers are designed to optimally couple the tube to to the load. In such a case the maximum Voltage and maximum current occur both at the rated impedance.
So our example amplifier of 100 Watt would not be able to supply more than 5 amps and more than 40 Volts which occurs precisely at 8 ohm. Both maxed out at the same time, so theoretically one point with maximum power.
Well those are the ratings. In reality the tube amp can deliver more than 5 amps or more than 40 Volts but not at the rated impedance. This flattens the ‘peak available power’ curve somewhat. Please note that this maximum power is more like a real ‘peak/RMS power’ unlike the two examples above.

With these three amplifiers you can understand that they favor different loudspeakers. The transistor amp theoretically matches well with a loudspeaker that has a low impedance  (<8 ohm)or impedance dips, the OTL favors high impedance ones (>16 ohms) and can handle impedance peaks well and the the transformer coupled tube amp is best served with a constant impedance at the rated value.

For sure there is much more to amplifiers than maximum deliverable power , but my experience is that this rule is implicitly followed by many ’system builders’.

Lastly I wanted to observe that an increase in power does translate into an equal amount of increase in sound pressure. Most amplifiers act as voltage amplifiers so the current follows the applied voltage. As the voice coils heat up and become more resistive, less power is absorbed for that voltage. Also speakers' excursion does not follow the power (and certainly not voltage) in a linear relationship extra power is less extra excursion than you expect.

This power transfer thing is where horns have big advantages. The compression drivers provide a very resistive load to the amplifier and they use low power, hence little heating of the voicemail occurs. And lastly excursion of the compression driver is extremely small and thus very linear. They are ideal candidates for transformer coupled tube amps, especially of the DHT variety that exhibit extremely low distortions at low signal levels.

I hope this helps somewhat to be more specific in what we try to say.

regards, Coen

Hi Peter,

Thanks for the clarification, horses for courses as they say!

regards, Coen