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My New Crown XTi 1000s Are Here!!


BEC

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Gee, Mike, Is that what those are called? I would say that's obvious enough -- the reason I mentioned the luxury of being able to make changes and adjustments. I have a couple of them, too. Actually, more than a couple of them. What's shown above isn't a finished product. From doing this a long time myself, I understand and appreciate the developmental stages, and what it takes to get there.

Cheers! :)

Erik

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I understand and appreciate the developmental stages, and what it takes to get there.

I understand and appreciate the develoment/tweaking/optimizing or whatever that Dean is doing as well.

But it's still just a piece of MDF(or Plywood) with terminal blocks and wire.....I mean it ain't that pretty, just functional.......his finished networks look nice....

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What makes the Xti a flop for audio work is the topology, which is a new creature for amplifiers.

On Jan.16, 2008 D Glass of Crown wrote:

"However, to put it in a little different light the topology used in the XTi is based of the same AB+B topology used in the DC300 series amplifiers which was a home audiophile amplifier standard for years. The only real difference is that with newer technologies we are able to produce an amplifier with more power, that has better efficiency, weighs less and cost less."

So a class AB amp with a DSP in front of it isn't good for audio? Or any DSP is no good? Or any AB SS amp is no good? Or only the ones that weigh less and cost less?

Don

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What makes the Xti a flop for audio work is the topology, which is a new creature for amplifiers.

On Jan.16, 2008 D Glass of Crown wrote:

"However, to put it in a little different light the topology used in the XTi is based of the same AB+B topology used in the DC300 series amplifiers which was a home audiophile amplifier standard for years. The only real difference is that with newer technologies we are able to produce an amplifier with more power, that has better efficiency, weighs less and cost less."

So a class AB amp with a DSP in front of it isn't good for audio? Or any DSP is no good? Or any AB SS amp is no good? Or only the ones that weigh less and cost less?

Don

Duke spinner says that the D150 and DC300 should both be put in the scrap heap! - To quote him 'They are both old and cold' !

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The Xti amp isn't good for audio work because it can't produce the fundamental minimum detail required in an audio ampliifer for home use.

What is minimum detail?

As far as comparing other amps, I've compared the XTI to Crown's XLS, an old SAE MKII, and the amp section of a Mitsubishi reciever. The XLS and Mitsu receiver were quiet listening about a foot from the HF horn, the XTI has an audible hiss that close. The SAE had more hiss than the XTI. All of these amps sounded acceptably good, with little difference in audible quality when each was used on HF in a tri-amped configuration with amp outputs hooked directly to the voice coils.

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Hi Duke -- the D75A is almost $175 more, and for that you get 12 extra ounces and 15 wpc. I don't really need the power, because I'm eventually going to biamp and the D45 will be on the top horn. I had to spread what money I had around a bit too -- Soniccraft just got $250 and another $300 is going to be chewed up in air cores and autoformers. So, the measley 25 wpc on my small rig will just have to do.:)

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"Minimum detail" is just my subjective term for what would be acceptable in a home audio amp. Detail includes all the tonal and spatial subtleties that allow one to differentiate close but different instruments, spatial locations, and hear individual tones buried in congested passages. If an amp is "cardboard flat" and produces zero front to back depth, and zero side to side space, it is lacking in spatial resolution. If an amp can scarcely differentiate the sound of two trumpets in a horn section, it is lacking in resolution. If an amp can't produce the sound of a glockenspiel lest it sounds like a set of backyard wind chimes, or makes all steel string guitars sound the same regardless of maker and player, that amp simply is not capable of serious audio work. And yet, it will be perfectly fine and wonderful announcing the next batter up at Yankee stadium. In that environment no one cares one hoot about all this detail I am describing. In fact, I dare say detail would be the enemy in that situation. PA amp is PERFECT for that application. You wouldn't use a nail gun to do delicate inlay work, right?

Hiss is the only problem that I have heard from the XTIs I have, and you have to be close to the HF horn to hear it. As far as resolving the details you mentioned, I'm hearing all of these things you mentioned now. The quality of the source and the loudspeaker have far more to do with the resolution of detail in a reproduction system than the amplification that is used. A poor room smears and ruins transient attacks to such a degree that any system is going to sound bad in that room, and any differences in amplification will be difficult to impossible to hear.

Having a 275 W/Ch amp running 1/3 W simply means that it's running in class A nearly all of the time. Amplifiers may interact with the loudspeaker load, and preamplifiers may interact with the power amp. These interactions probably cause most of the differences heard in amplification equipment. Pro amplifiers are designed to drive difficult loads and to deliver massive output when called upon to do so. Pro equipment is designed to work any other equipment, balanced or unbalanced, with few interfacing problems. Pro equipment handles power surges and transients with less chance of damage or audible consequences. Pro amps aren't like nail guns, but rather like 16# mauls that can drive tacks.

Don

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Power surges and ground bounce transients usually do more damage passing through a power stage to components beyond than damage to the power supply itself. Spikes and switching transients create energy up in the 1-2 mhz range and are best filtered by RFI/EMI suppression where power enters the equipment before it is rectified. Once this HF energy gets into any equipment, all bets are off as to damage, with CMOS devices being the most sensitive to this sort of damage, other SS devices right behind. Crown has EMI filtration on the XTI's power input.

I can't speak for the D45's power supply components, but it is not good to run 35V caps at 31V continuously on anything. Poor design, IMO. Vacuum tubes are inherently immune to spikes and surges - they are designed to operate at high voltage, and components are so rated. You never used to hear about power surges and surge damage or see surge protectors back then.

Don

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"Dean, You shouldn't need any autoformers."

That's an accurate assessment. An autoformer is simply a way of balancing driver outputs. The majority of crossover networks use L-pads consisting of either a single series (as in on network design that was posted for the Jubilee), or one in series and another in parallel to maintain the original impedance of the driver being attenuated. The autoformer can also be replaced by resistors on ANY of the older networks, however that makes them less like the original design. Mr. Klipsch preferred the autoformer; other equally well-known companies used and continue to use resistors. Both work.

Since there is no autoformer on the new Klipsch Heritage networks I've seen, I was wondering why they are no longer in the picture. Possibly for a reduction in cost, etc.

I suspect only Klipsch knows the answer to that, which is absolutely fine. I'm confident in their engineering.

Erik

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