Review of Dartzeel NHB-108 Amplifier

Sean; i've kinda got frustrated with this thread. i even sent Mr. Audiogon a post complaining (for the first time ever) about 'delays pending moderator approval'. if the 'gon' wants to slow down a thread, that is their business......but then i just lose interest. i never 'stir the s**t' and resent being treated as if i do. i suppose it is easier to simply filter threads instead of individual 'goners'.......but i don't like it.

end of rant.

yes, Rives Audio did 'do the math' on speaker and listeneing position placement......which turned up 2 'best spots' for my listening position and one ideal speaker position. i am sitting within 4 inches of the more near-field of the two listening positions. the speakers are about 6 inches closer together and 4 inches forward of the original suggestion.

i don't know exactly how Richard Bird did the math, but you could ask him.

i moved the speakers all over the place and the bass performance was essentially the same......so i ended up just focusing on the soundstage. since the speakers are so far away from room boundaries wherever i put them; there were no changes in the tonal balance as i moved them around. what is almost spooky is how balanced the room sounds as you move around......the soundstage resembles how live music sounds as you would move around a nightclub.

it will be interesting to see how the VR9's will do.

i'm no speaker designer and don't pretend to be. i'm not sure about just how extensive your experience is with the VR9......but your conjecture about how many if it's design choices MIGHT affect performance seems a little too 'all-knowing' in it's tone without some extensive personal auditioning.

after spending hours speaking to Kevin Malgrem, the primary designer of the VR9 and VR11, about how choices were made in it's design......my OPINION is that your theories may not be correct.....but i admit to not being an expert......although i do have a fair amount of high performance speaker listening experience.

i did spend 10 to 12 hours listening to the VR9 at CES. my perceptions are not consistent with your theories. you are guessing about how the crossover is actually designed and exactly how parts are used. you are guessing about how low the front mounted woofers go. many speakers use a rear mounted port for deep bass support (Kharma)......and yet there is no backwave discontinuity percieved......why would a rear mounted subwoofer be any different (unless you listened and identified the cause and effect)......or had experience with that issue on other speakers.

many designers don't disclose exactly what they are doing (Wilson, Kharma)......you gotta listen to judge.

you could be absolutely right.....or absolutely wrong......but only listening will tell that.

Sean writes:

Jtinn: Jenna's cables are based on a woven pattern. While the cables may present a consistent nominal impedance when measured at one end, the design geometry consists of multitudes of impedance bumps along the entire path of the cabling.

That doesn't make much sense to me. How do you know these "impedance bumps" are there? How can you measure them?

Regards,

Cinematic Systems, do not twist everyone's statements out of context and use it to make broad sweeping statements about one's meaning. I can do the same and declare that your statement that seems to imply that jazz musicans don't know what they're doing, shows your lack of knowledge and ignorance. You used the label/term musicians broadly, while I almost clearly defined them. Explain to me, how a musician, who has no interest in putting out a record, NEEDs people like you? If you think I'm arrogant for saying that to musicians who simply enjoy playing music, people like you are irrelevant, than so be it.

In historiography, the "official scholar" and recorder of dynastic history is important because he has the power to "twist" history, not because he is "needed". Written history has made it easier for historians, but history has been passed along fine without being written down. Are recording engineers and such important? Yes to the recording process. Music has been played for many centuries without being "recorded". It's arrogant to think that people need you to record them in order to play music and be a musician.

There's a common belief that the best musician in the world, if there is one, is probably sitting at home practicing. It's certainly a lot merrier playing music with others, but again, you don't NEED anyone to play music.

If planet Earth is near extinction, you'll find people playing music and you'll find people who thinks music is important and inspiring. Good luck finding people who think your job is relevant.

Howie: I am surprised :)

Mike: Speaker design is a science more-so than it is an "art". While many in the design / manufacturing / distribution / sales / reviewing industries of "high end" audio would have you believe otherwise i.e. "the talented and very secretive audio guru's working their black magic", etc..., without the science, formula's and consistencies noted amongst specific design parameters, speaker design would be more "guesswork" than "art". As such, applying the science, formula's and commonalities amongst operating parameters is what makes up about 90% of the speaker design. The other 10% is finessing the variables into place to achieve the specific voicing / electrical characteristics that are desired.

Whether or not one agrees with the specific figures ( 90% / 10% ) i used, i don't think that anyone familiar with the nuts & bolts of speaker design will question the comments that i made to any great extent. That's because they've studied the science enough to know what to expect out of a product based on how repeatable design parameters are implimented, sometimes even before they hear the product itself.

The only real "catch" here is the "10%" that is art / magic, which can take a poor design and make it listenable, a mediocre design and make it more enjoyable than expected i.e. "a world beater that is greater than the sum of the parts", a good design and make it into something truly enjoyable, etc...

On the other hand, one can have all the "right parts" and a great circuit with a very poor implimentation. As such, that last 10% could kill what should have been at least a decent product.

The point that i'm getting at is that 90% of the equation starts with the design i.e. the consistent and repeatable performance characteristics that are predictable based on science and math. The finesse factor / how it is implimented is what makes the difference once all of the science / math have been implimented. In this case, most of the "science" is pretty straight-forward, hence the ability to describe specific sonic attributes and electrical characteristics onto it as a product. As i mentioned, what instrument radiates 100% of the sound that it produces away from the listener?

With that in mind, i'm not saying that you or someone else can't or won't like this speaker. What i am saying is that based on the money involved and the other design approaches that could have been taken, the end product seems to be questionable in both value and performance. Then again, most every "high end" speaker falls into that category to one degree or another with some being far more questionable than others.

As a side note, this is a 94 dB speaker according to Von Schweikert's website. The rating of 96 dB's only applies if the bass and treble boost circuitry are engaged. In effect, it looks like the active equalization circuitry ( fancy tone controls ) not only increases the average sensitivity, but also delivers the "big & dynamic" ( bright and thumpy ) sound that so many "audiophiles" seem to like. The fact that Legacy voices their products in much the same fashion shows that personal preference may be a better selling tool than accuracy and linearity are. At least with Legacy products though, you do get a lot of driver surface area for the money. In that respect, they are a "bargain" amongst "high end" speakers, even if they aren't anything close to what "high end" audio USED to be about.

Metralla: How do i know that this cable has impedance bumps? That's easy. I have eyes and know how to interpret what i see : )

Honestly though, much of the "science" discussed above that makes speaker design repeatable also applies to the conductivity and electric parameters of cable design too.

I'll try to keep this simple. A conductor in free space presents a specific impedance / velocity of propogation. Placing other conductive objects in proximity close enough to disturb or "couple" to the field produced by the conductor passing signal will change both the impedance and velocity of the signal.

Given that the cable design being discussed consists of a woven pattern, you'll have a conductor that is "somewhat" in free space and then that conductor is placed above / below / next to another conductor. It then hits an open gap in the weave and then is placed in close proximity to another conductor above / below / next to it. This produces a random yet repeated change in impedance until the end of the pattern.

Think of the electrons in the cable as a car and the woven pattern as traffic on an expressway. In some spots, the car can pick up speed as there is no impediment to flow i.e. open space all around it. Once it hits a pack of cars ( enters an "intersection" in the weave ), the speed of travel ( velocity of propagation ) has to be altered. Once the car ( electron ) makes it through the congested intersection ( areas where conductor cross section comes in contact or closer proximity with each other ), it can now procede ahead at full speed as there is a open area i.e. another "gap" in the traffic before it has to weave in and out of the traffic, slowing down progress once again.

When looking at the progress that the car ( electron ) made travelling from point A to point B, we can ascertain the "average speed" ( nominal impedance ) that it took. Only problem is, that average speed is a combo of both "open road" speeds and "heavily congested traffic" speeds, which equate to the different impedances, "electrical bumps" and velocities that the electrons encountered.

As to my vantage point, i'm in a helicopter flying overhead going directly from point A to point B. Not only can i see all of the changes in traffic flow ( impedance alterations ), but i've got a much shorter path since i don't have to weave around other obstacles, which requires me to alter my speed. Once again, this is why the shortest and straightest path is typically the fastest and most consistent route. I also new what to expect in terms of traffic flow ( impedance and speed of conduction ) as i had observed these characteristics many times before with both my naked eyes ( visible traits ) and by studying traffic logging data ( test results ). Knowing what to expect on any adventure and how best to deal with the variables involved can be rewarding in both time and monetary expenses. This is why educating yourself on the subjects that you'll be dealing with is both wise and enjoyable i.e. it pays for itself.

Hope this helps and made the explanation easy enough to follow. Sean
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PS... That explanation is pretty rudimentary, but it gets the point across.