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Crown XTi 2000 vs. Denon 5803


jacksonbart

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This evening I got the Art Clean box, the XLR cables from Blue Jeans and the Crown XTi 2000 in the mail. Well thanks to the fellow forum members, especially Coytee, I set everything up. I am lucky in that I have the Olive Music server, Denon 3910 and the 5803 built into a cabinet that is against a false wall, so it’s easy to set up the XTi and the clean box in the storage area, next to the listening/movie room. I read the manual of the Crown at work even before I got it by downloading the Adobe PDF, so set up was easy. I am not so crazy about the channel #1, #2 vs. left, right but I got that figured out quickly. Once I got the Crown fired up I did notice more of a “pffffffffffffffff” sound coming from the RF7s. With the Denon 5803 you really need to put your head right to the tweeter to hear any slight hiss. The Crown gave off a more pronounced atmosphere than a hiss but I could hear it. Thinking it was my connections I simply connected the speaker wires to the crown and nothing else and it was there. Basically they were removed straight from the Denon to the Crown and I could hear it. It was neither a hum nor distracting, just a difference. Is that normal?? I’m I the only one to hear that? I set the Denon to turn off the RSW15 and just use the RF7s as large. Listening to EC’s Unplugged and Keb Mo’s ‘The Door’ on SACD, I noticed more upper detail with the Crown, more spaciousness, plus more bass for sure, the “pfffffff” immediately disappeared and the music was there. For me it was not life changing, but very nice/different. The Denon was warmer sounding to some degree at lower levels. I also connected the Denon 3910 directly to the Crown via the Clean Box just to ensure the 5803 was not negatively affecting anything. Even at louder volumes the Crown was easier to listen too, it really impressed me about how loud and clean the RF7’s would play, they never sounded strained, just great music, as if it was live. The Crown never indicated -20 towards clipping and it was still cool to the touch. Right now I am listening to the Denon 5803 as a pre-amp with the RSW-15 handling the 60 Hz and below and the Crown connected to the RF-7s. I am enjoying this experiment. I would say I probably could have gotten by with the XTi 1000, but all in all very interesting and I have much more listening ahead.

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Dare I say, "Top notch"?

I had trouble with the 6922 tube in my BBX that I got from JWC in the summer. Crazy oscillation and weird noises. I tried some I had in my Dynaco ST-70 mod, and they were even more erratic. Mark suggessted to somone else that they just get one of the EH 6922 tubes, so I tried one as well. For $12, I wouldn't be out much. I can now hear the hiss from the BBX, but just barely. As soon as the music starts it is gone.

I guess I am saying that you can probably put up with the noise. Will the noise floor drop if you turn down the gain some on the Crown? Then up the output on the pre a bit to compensate.

Bruce

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Jack congrats on the xti...I have been a day late and a dollar
short on a few different used ones. I have heard good things about them
especially when you can hook up your comp and start fooling with the
signals. Also I have heard that the ART box rolls off the lower
frequencies pretty significantly if you don't modify it...someone on
this forum directed me to this page when I was looking at buying one in
the Garage Sale section. The solution is to replace two small caps I
believe...this of course may not be the case but take a listen and see
what you think. This may not be imporntant since you are using it for
the rf-7's. I don't know about you but I love it when I make a
improvement to my system and someone says...hey why don't you do this
too...take it with a grain of salt.

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Nice write up.

Also I have heard that the ART box rolls off the lower frequencies pretty significantly if you don't modify it...

It's only significant if you're using a subwoofer with material below 20Hz. Don't forget about room gain, in many setups the rolloff might actually be a good thing.

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Oh sure...blame me...

Why do I smell Buckster behind this frame-up...

As for

I simply connected the speaker wires to the crown and nothing else and it was there.

, Might we presume you had the inputs to the amp shorted out? When I was having some issues, although with an RCA input amp, I was told to hook my speakers up, create a shorting plug on the input jacks and by doing that, I'd then be hearing JUST the amp and any noise it might have. You probably know this. One thing I don't know is how to short/ground a XLR input.

More bass too? bummer huh!! [H]

So, is it less filling or more bass?

[Y]

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You think the short would describe the extra "pffffffffff"? Do you experiance the same with your Jubs?

Depending on your point of view the Denon seems rolled off a bit in the high frequencies with a slight bump in the lower mid range (sorry I am not a techie). The Crown really seems to make the RF7's horn wake up/pop, the highs are much more pronounced and not the same as if I just cranked up the treble on the Denon. With the Crown, on opening to Clapton Unplugged, you could really hear the musicians set up with thier instruments and the crowd at the very beginning of Signe. It was very well spaced out in the room. The Denon was much more laid back in the same part, but you could hear/almost feel the foot taping of I assume Clapton being more pronounced. Again all subtle differences, not earth shattering. I wonder since I was using the Denon if perhaps that was why I didn't understand so many people calling the RF-7s as overly bright? Even on the Crown yet I would not say they are overly bright, just more in your face. I really can't listen to background music with the Crown/RF7 combo at least I haven't been able to, its much more involving, though I think I prefer the Denon at lower volumes at this point. Sorry for the rambling.

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You think the short would describe the extra "pffffffffff"? Do you experiance the same with your Jubs

First, a bit of background. I was going from RCA outputs on my Peach to XLR inputs on my crossover using a home made wire with XLR on one end and RCA on the other end. I was having some noise issues although my "pffff" usually ended like "pffffffTTT" (as my wife stomps away... [:$])

Ok.. so once I unhooked ALL the wires (even the input, however, I unhooked it on the RCA side, leaving the XLR side plugged in, thinking it was totally disconnected)

Anyways, once I did that, I still had issues so I touched a screwdriver to the RCA center pin to the RCA sleeve or what ever the outer part of it is called. The instant I did that, virtually ALL noise ended and it was at that moment that my lightbulb finally went off as to what Mike meant when he told me about shorting it as well as after having done it that "this insures that the only "noise" you might hear will be from your amps"

So, in my case, other than my wife 'pffffffting' at me [*-)], I'd say yes, shorting the input DID clear up that issue. More specifically, it helped prove to me that it was my XLR/RCA wire that was really my specific problem because once I put the Cleanbox back into the loop, virtually all the noise disappeared except for some, as you say, pfffff (no wife this time)

Now what I find, my input gain to my Peach is higher and I can be literally sitting across the room with the volume completely OFF and if I have my Left/Right attenuaters on my Peach at the 12:00 position, I can "clearly" (as defined as faint) hear bleed through of what ever is playing, in spite of my volume being off. If I turn my attenuaters FULL on or maybe take them back to 9:00, the bleedthrough will subside to the point of being gone. Seems the 12:00 on the attenuaters is the point of maximum noise. I once asked Mark about this and although I do NOT understand the technical part of it, he agreed that the 12:00 postion is where (butchering his comments here) "the tube pulls from both sides of the signal...blah blah blah..." I don't know if at that time, he realized I was juicing up the input strength by using this cleanbox because he seemed genuinely surprised that I'd make comment about this much noise and bleedthrough. Indeed, I've since made casual comment and someone read my comments and clearly pointed out that THEIR Peach didn't have ANY noise "at 12:00" (well, nanny nanny to me, they probably didn't realize the different plumbing I was running [:o])

Sooooo... all that to say "yes" lol

You should listen to David Gilmour's "Meltdown concert". I will sometimes put it on to JUST listen to the opening of it as he's standing there on the stage with his acoustic guitar, starting his song. He pushes various buttons with his feet (to control his guitar) and the floor squeeks, the equipment clicks... it is a VERY "you are there" kind of thing. I really get a kick out of all the detail of just the beginning of that concert. Much like you say..."you could really hear the musicisans set up with their insruments..." Very top notch!

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Coytee, you know that it is a LOT easier to short out amps by dropping your drink cup on top of the case while your listening to loud music. The result is that you hear a nice fluid, smooth sound that caresses the ear as the sparks fly inside the unit... ;)

It's very ironic you mention that today as the day before yesterday I was helping the wife load an item onto Ebay. She had placed a (fortunately NEAR empty) cup of hot tea near the mouse. As I reached over for the mouse, hand hit cup, cup went sprawling and soaked the side of the pc box.

No problem you say... they have sides of solid steel. Yes... EXCEPT for the vent holes which just happens to be where the lip of the cup hit as it was falling to the ground, spilling its (thankfully nil) contents on the side of the box and INTO said vent holes.

PC immediately freaked out, video feed turned 100% blocky/pixelish and I had to take side off and dry off some drops that got inside. Must have been perfect trajectories to the video card.

[:D]

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Just out of curiosity, I am a bit confused as to what point many are trying to prove.

Are you trying to blame the interface unit, or the fundamental operation being performed, or what?

As far as the basic fact that you are going from unbalanced to balanced, you might want to acknowlege some fundamentals. And having done so, THEN try to ascertain exactly what the source of the problem is that is being complained about.

"Unbalanced interconnections are inherently prone to noise because
the grounded conductor, which most often also serves as the cable
shield, is not only part of the signal circuit, but also a path for
small power line currents. These unavoidable power line leakage
currents will always flow in any wire connecting pieces of equipment
together. In an unbalanced interconnection, as these currents flow
through the resistance of the grounded (shield) conductor, the
resulting voltage drop is directly added to the signal voltage. This
common-impedance coupling causes virtually all hum and buzz
problems in unbalanced interfaces." [Whitlock, Interconnection of
Balanced and Unbalanced Equipment
, Jensen Application Note AN003

You can check the Whitlock papers posted on Jensen website for the referred schematics, but here is a bit of information that addresses some of the various topologies you may find usefull for such an endeavor. My suggestion is to reasearch Bill Whitlock and Neil Muncy's references.

"UNBALANCED-TO-BALANCED INTERFACES












i'd like to direct your attention first to Figure 1B. This schematic
shows a commonly used, but noise-prone, method using 2-conductor
(shielded single conductor) cable and an RCA-to-XLR adapter at the
input. Do not use this adapter — it results in zero ground noise
rejection. All the potential noise-reduction benefit of the balanced
input is wasted. Sadly, many commercial cable assemblies are wired
exactly this way.

















203MixMatchFig1Bcapt.jpg

















Figure 1A shows a much better way to connect an unbalanced output to
a balanced input. Sometimes called a pseudo-balanced connection,
this method allows power line leakage currents to flow in the shield of
a 3-conductor (shielded twisted pair) cable. This allows the balanced
input to sense the signal at the unbalanced output and reject the
common-mode ground noise. The 470-ohm impedance of the unbalanced
output will degrade the 60Hz CMRR of the typical balanced input to
about 30 dB, but that's still 30 dB better than using the adapter! For
all intents and purposes, using a pseudo-balanced connection is
the correct way to connect an unbalanced component to a balanced
one. Now, let's look at the best way to add a transformer into the
system.

















cleansignals1A.gif

















Adding a Transformer. The interface in Figure 1C uses a conventional
transformer to improve the impedance balance. This will reduce the CMRR
degradation of the balanced input stage at low frequencies. In this
circuit, CMRR will be about 55 dB at 60 Hz, but because of the
inter-winding capacitance in the transformer, CMRR will gradually fall
to about 30 dB at frequencies over 1 kHz. Compared to the correct
adapter cable of Figure 1A, it doesn't improve buzz, which contains
many high-frequency components, but it does reduce 60Hz hum by another
25 dB.

















cleansignals1C.gif

















With rare exceptions, transformers used in hum eliminator boxes are
conventional designs that don't include a Faraday (electrostatic)
shield between the windings to prevent capacitive coupling between
primary and secondary windings.

















The interface in Figure 1D uses a Faraday-shielded, or
input-style, transformer to improve the tolerance of the input
stage to impedance imbalances. The input transformer, unlike the input
stage itself, can tolerate large source impedance unbalances with very
little CMRR degradation. In this circuit, CMRR will be about 100 dB at
60 Hz and 70 dB at 3 kHz, making it very effective at eliminating both
the hum and buzz components. (Faraday-shielded transformers are used in
most Jensen ISO-MAX isolator boxes.)

















cleansignals1D.gif

















None of the interfaces shown in these figures provides the 12dB gain
necessary to increase the nominal -10dBV (316 mV) consumer reference
level to the nominal +4dBu (1.23V) professional reference level. In the
rare case where the pro equipment doesn't have enough available gain,
an active amplifier may be necessary.

















One might ask, “Why not use a 1:4 step-up transformer to get
the voltage gain?” A step-up transformer, even if ideal (i.e.,
without any loss) is not a viable source of gain in this application.
Reflected impedances cause excess loading of the consumer output,
leading to an actual loss of gain, compromised low-frequency response
and increased distortion." [Whitlock, “Audio Transformer
Basics,” Handbook for Sound Engineers, Third Edition, Glen
Ballou Editor, Focal Press, 2002, Chapter 11, pp. 254-256.]

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Is this pfffff sound you guys are describing a high frequency hissing type sound (almost like static)? Is it audible at the listening position?

The XTi is rated with a noise floor of 100 dBA...which means any noise you hear should be 100dB down from the peak acoustical output of your speakers with the amp at full power. In other words, you're talking like below 30dB. (Hmmmm...that seems off - I'll have to check my math when I'm not so tired).

It seems odd that multiple people are having this problem though. I would probably give Crown Tech Support a call. They tend to be very helpful. Does anyone notice this issue that is using the XTi 1000?

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I wasn't attempting to point the blame at anything other than my own ignorance =) I am very new at everything audio but am wanting to learn as much as I can. The article you posted looks like it will be very helpful - I'll go over it tomorrow at a reasonable hour.

Dr - I'll post about the sound (more specifically) tomorrow as well - don't want to power everything up and be tempted to play a song while people in the house are sleeping =D

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Here you go...Here is a Whitlock Doc that should resolve these issues.

Note, with the Crown you should be good to go with imply the cable, as their input sensitivity covers a pretty broad range.

Its a bit strange, as I have not haad trouble with the Rolls MD15 Promatch with any noise...but everyone seems to be rushing to get the Art product (and I haven't taken the time to compare schematics). As Doc asked, are you guys running the 2000 wide open?

an003.Interconnection ofBalAndUnbalEquip.pdf

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I can run the QSC SRA 2422 wide open without the slightest hum, hiss , buzz or any other noise with my ear at the mouth of the horn. And actually this is the first amp I have ever had hooked up to my Chorus II's that I could say that. My so called home audiophile amps always have had some noise.

Pro amps can be dead silent. I think there must be something going on here with one of the other devices or cabling.

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I was not getting any hum, buzz, creaking, etc or other noise, other than a slight "pffffffffff" as beng distinct from just using the Denon. My room typically has a very low noise floor. I am using the art clean box. When my wife and friends walked into the room with the crown hooked up, they noticed nothing, even when I pointed it out. Its only appearent to me when I switched between the two. Again its more like added atmosphere if you will. It disappears with the music and after being in the room you have to turn off the crown to notice it gone in a silent room. Its very slight and does not bother me, just wondered if it was normal. I think it has to do with the Crown's ability to handle highs better than the Denon. Perhaps I am just not deaf enough, but I am sure that will come with time.

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