Review of Dartzeel NHB-108 Amplifier

Sirspeedy: Well said!

Well, since i tried to be a "nice guy" and get back on track with my "calmer, more friendly" New Year's Resolution in previous attempts to reply to this thread, and they didn't make it through moderator approval, i guess i'll resort to the point by point response that i really didn't want to have to make.

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. The multitude of impedance variations is what makes up that nominal impedance and increases the potential for rejecting RFI. That's because one consistent impedance is easier for an RF signal to propagate itself upon / within, hence the multitude of impedance bumps making it tougher to pass an RF signal.

On top of that, impedance bumps create phase shifts, which in turn creates smearing. On top of that ( part II ), it is very difficult for all of the conductors within a mass produced multi-strand cable to remain the exact same length, giving the signal multiple length paths to choose from. This also increases smearing due to differences in arrival times. I could continue further with this, but no need to.

As far as speaker or product design goes, i don't have to build or market anything to have a basic understanding of parts quality and / or design theory and / or understanding on how instruments work and / or understanding on the room / speaker interface and / or the audible perception of various radiation patterns. What products do you design / manufacture to think you know so much? What technical and / or electronics credentials do you have to question my credentials?

As far as Solen's go, they are a great bang for the buck product. I don't think that anyone familiar with them would deny that. When compared to some other caps that shall remain nameless, the only reason that one would select the Solen's would be a matter of keeping production costs lower. The fact that the Von Schweikert website specifically mentions the use of Solen caps in the crossover led me to believe that they were the primary ingredient in terms of capacitors used, hence their trying to play up the use of a recognized "hi-fi" brand name. I didn't see any other brands of capacitors or inductors mentioned, so what would lead me to believe that others were used??? The fact that you said that there is ONE Solen used in the crossover circuit leads me to believe that this is either the only cap used, or that there are others used, but of lesser quality. If this were not true, i would think that they would have listed the names of the higher quality caps rather than settling for Solen as the "high end" buzzword.

As far as one woofer goes, a speaker of this cost using one woofer seems rather cut-corner to me. Since output capacity is directly related to driver displacement, one would think that multiple drivers would be a natural here, especially at this price range. That is, unless the designer thinks that one large diameter, long excursion driver is sufficient. The problem with that is that it is common knowledge that the more excursion that a driver has to make, the more non-linear the output i.e. distortion starts to climb. Using multiple drivers of the same surface area reduces the amount of excursion necessary, lowers distortion, increases maximum sustainable spl's, increases dynamic headroom, lowers thermal stress on each of the individual drivers, etc... If designed properly, a multiple woofer system can also load the room more effectively, therefore producing more consistent response.

As to the 80 Hz crossover, this is a bit high for use as a "subwoofer". The name "sub-woofer" implies output below the normal frequency range of a woofer. On top of that, 80 Hz is more easy to localize than if a lower crossover point were used. This has to do with the fact that a higher percentage of room nodes will be excited than if output were actually kept down low i.e. in the SUB-woofer frequency range.

As to the rear placement of the driver, the length of the signal path from all of the other drivers to the seated listening position compared to that of the "subwoofer" aren't anywhere near the same length. On top of that, please name one instrument that produces low frequencies and radiates them in the opposite direction of that of the listener with NO direct radiation towards the listener at all. Even a kettle drum or pipe organ will radiate some of the sound forward off of the stage. Without this frontal wave, all of these instruments would produce completely different attack and decay characteristics to our ears and change the timbre of the instruments as we know them and hear them.

Other than that, it is convenient of you to overlook some of the other things that i've said about you in a positive manner. Obviously, your attempt to portray me as being "anti-Jonathan Tinn" is a ruse to distract others from the real matters at hand. I don't care who you are or what you sell, so long as you represent yourself and the products that you push honestly.

As i've said before, i try to call them as i see them. My comments in this thread, and all the others that i've contributed to, are simply my honest opinions. If you've got a problem with that, that's your problem. If i've stated incorrect information in this or other posts, that's OUR problem. Please feel free to correct my mistakes as you see fit and make me aware of the corrections. I want to learn from my mistakes. That's pretty much the only reason i know what i do i.e. i've made a LOT of mistakes and learned from them in the past.

As i've stated before, my "mission" is to share, learn and educate, not mislead by posting misinformation. I've always tried to do my best and be as honest as i can, even if i've gone overboard on some points. I hope others can recognize my efforts for what they are. I'm not looking for praise, just mutual respect from my fellow audiophiles that take the time to learn and share with me as a group. We don't always have to agree to be friends or discuss matters in an open manner. Sean
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PS... Mike, i'm still wondering about my question pertaining to the computer modeling / room simulations of various speakers & speaker placements in your room. Have you ever tried this and compared the results in terms of perceived sonics vs predicted results?

Well, I guess it's safe to reenter the thread, since most of the bickering and sniping seems to have stopped. This has been said ad nauseum, but it bears repeating again here: we're in this hobby for one reason and one reason only--to connect with the music in the deepest, most spiritual sort of way. Whether some people prefer Kharma or not, DarTZeel or not, it's not for us to judge. Sound quality is so subjective that, really, NO choice is wrong, provided the person enjoys that equipment. What ruins it, here and on Audio Asylum, is when ego struggles get involved. Person A thinks Von Schweikert speakers are the best on the market; person B thinks Kharmas are. Neither one wants to back down, it soon turns personal, and the potential for truly meaningful discussion is ruined. I truly believe that individual ego destroys at least 25% of threads initiated here and on AA. People either can't let go of their agenda, or they refuse to lose an argument, and soon it turns into a spiraling bicker-fest. It happened here, which is a shame because I wanted this thread to be an amicable forum to discuss the wonderful DarTZeel amplifier. Oh well, I guess I should have expected it. It started out well, though.

Sirspeedy,

Where can I get a copy of this book?

Thanks

Wow Sean, what a wealth of technical details. Thank you as there is always much to learn from your inputs.

As Sean mentions, we try to maintain our "more friendly" nature but sometimes things are written here that just fire us up. And no matter how hard we might try to get a point across, some people just don't get it. It's not the difference in viewpoints - it's the ability to listen to and understand other viewpoints. Only a few days ago I was told by someone here I needed a lesson in internet etiquette. Well at least in this thread I have behaved myself.

And yes Hooper, it's unfortunate that your attempts to share your amplifier experiences shifted to a speaker dogfight here. But I think it's very clear the amplifiers and speakers covered extensively in this thread have great merit to get so much praise from a number of highly respected Audiogon members.

John