sfogg

Averaged...

real time on scope

At 10kHz, harmonics are at 20kHz and above.

Average.....

real time

Same thing at 5k....

with averaging to pull the corrolated signal out of random noise...

On the scope in real time....

Same thing but at 1kHz. Harmonics are a little higher here....

.... because of noise in the output. Same thing but applying averaging in the scope to pull the signal out of the noise. Signal itself looks fine again...

However if you look at this on a scope it looks nasty.

Tried looking at distortion at 1v output into 8 ohm load. This is about 0.12w output. 500hz is the fundamental all the other markers are at harmonics of 500hz. The second harmonic is down almost 75dB, that is low distortion. Shawn

OK, had a little bit of time with the Crown on the bench tonight. First things first... my Crown seems to have about a 3dB boost at 20kHz as compared to 1kHz. The FR starts heading up at abot 5kHz. I checked this with DSP OFF and with DSP OFF and the Limiter turned off too as set by the front panel. I want to plug in the computer to verify all the settings are flat though, it is totally possible there could be a bug in the interface. Also for those biamping Jubs with the Crown and Roys numbers it is possible this was accounted for when he worked up the measurements for the Crowns. This boost was consistent at 1v output, 3.3v output and 9.1v out all referenced to 1kHz. Next up some distortion measurements.... Shawn

"i did read on one projector that it had a range from 11' to 26', so i am assuming that i can mount it at around 15' and have no issues." Bad assumption. Each projector has a throw range which is a ratio of the screen width to projector mounting distance. This ratio varies a fair amount between projectors. And if you do not know what your screen size is going to be you have no idea where the projector is going to be mounted. Likewise without knowing what projector you are looking at you don't know the ratio you have to work with. Some projectors are short throw, some are medium, some are long throw and some have a wide range of zoom/throw options. Like wise without knowing the projector you do not know where the projector is mounted vertically in relationship to the screen. Some have lens shift, some do not. "if i go with the screen size (2.35) then most of the movies i will watch will fit with no black bars?" Look on the backs of your movies. They will give the aspect ratio. See which ones are 2.35 and which ones aren't. "if the moves doesn't have that ratio, then i can use the scaler or zoom to make it fit just right? i don't want any distortion so i would like to know what is the best way to go. " You can't have it both ways. If you fill the 2.35 aspect ratio screen on movies that aren't 2.35 you are introducing distortions to the picture. If you don't want distortions you will have black bars on the *sides* of the picture. Shawn

"- those little RedTrader hones are just too *** small. " That has been my problem with them. They also badly needed to be flattened. I made much more progress after flattening them but the straights just aren't there yet they pull way too much. A larger hone would help greatly I'm sure. "I also have a 12k Chinese, and the various Tony Miller pasted (.5 and 1.0) and hanging strops.." Nice, I have one of Tony's strops too. A 3" Heirloom Artisan dual w/Red Latigo and Horsehide surfaces. Really nice product. "Not as difficult as it seems, gives great satisfaction when done well, no plastic in the landfills and only cuts me when I am careless.." Yup, I took a wack at it this morning (based on this thread) with the custom Wade and Butcher which came honed. Went well, much better then the first time I tried a DE and no blood letting at all. I think starting on the DE likely helped a lot since I already know all the angles and such. Thanks, Shawn

Nice.I have a couple of Wade and Butcher (one in custom wood scales), a Boker, Geneva, Torrey, HMC and the craziest is an Iwasaki. The Iwasaki is seriously shave ready but I'm not sure that is a good one to learn on. RAD hits hard. What hones do you use? I have a set of the Red Trader hones but haven't gotten the others there yet with them.Going back and forth between a Norton 4k/8k or a Blue+Yellow Belgian. Shawn

How much are you looking to spend on the projector and screen? Budget will help narrow things down a little bit. Native 1080p projectors are available from around $2500 and up. Make sure you have *total* light control in your new room. You need the room dark or it will wash out the picture. Where you put the projector depends upon the projector itself. There is quite a bit of difference between the placement of various projectors based on their throw range and if they offer horizontal or vertical lens shift. "scalier and zoom (that way i have no black bars no matter what "widescreen" dvd i have" Keep in mind in doing this (if you use a standard 16:9/1.78 AR screen) you are going to be cropping some of the picture on 2.35AR movies. On some movies you might not notice, in others characters will literally be off the screen. If you are thinking about black bars above/below the picture (on say Star Wars or anything else 2.35 AR) consider a constant height setup. This is what a movie theater does. You use a 2.35 AR screen (W-I-D-E-S-C-R-E-E-N) and your picture always fill the heigh of the screen. You just may use less width of the screen for your non-2.35 AR sources. Much more cinematic this way and you can easily mask the unused screen width with curtains if desired. Constant height is a more involved setup though with some additional complexity and potentially cost depending upon how you do it. Also... with a 2.35 setup there are video processors out there which can take your <2.35 AR sources and perform a non-linear stretch to them so that they fill the screen all the time. The non-linear stretch leaves the middle of the picture alone and stretchs the sides more and more to fill the screen. Doing this you don't end up cropping anyone out of a 2.35 movie but you obviously introduce geometric distortions to your <2.35 sources. Which way to go depends upon what you want and what kind of sources you expect to play on it. If you are just going to be watching 16:9 TV all the time the CH setup isn't worth it. But if you will be watching a lot of movies a 2.35 setup is impressive. Shawn

Along the same lines check out: http://www.theonion.com/content/node/33930 Which came out about a year before Gillette released a 5 bladed razor.... Shawn

Double edged safety razors. Smoother shaves with much less irritation then the Mach5 or Sensors I used before it. Blades cost about $0.07 each in quantity. Usually with Trumpers or Mitchells Wool Fat shaving soap. I have a couple of straights I want to learn on too but haven't had the time to really get them honed perfectly yet. Shawn

Dean, "Shawn, at the top of Bob's plot I believe it says, "Input random noise at 500mv 1 watt output 8 ohms"." Thanks, I missed that. One possibility is that the variations may be from the random noise. I think Bob applied averaging to that measurement, which he should since noise will have a Crest factor. What I can't tell from that graph is if this is a transfer function or just a straight measurement of the noise. If it is a transfer function the graph is basically showing the difference between the input and the output, in which case the variations are being introduced by the amp. A transfer function may not work properly on the XTI though due to the latency through it. I'll have to try that when I receive mine to see what that looks like. If this is a straight measurement of the noise itself it could be the noise isn't flat or that the amp isn't flat or there wasn't enough averaging to even out the Crest factor. Measuring hundreds/thousands of points (size of the FFT) all at once with noise is a little different then measuring a couple of dozen points one at a time with an oscilator. Shawn

Bob, "FR test on Crown XTi 1000 at one watt with resolution of 1 db per major division." Is that done with a frequency sweep or with some form of noise? Shawn

"Yup Class A, zero feedback Single Ended Triode........ how long did you spend to find that reveiw from 1995" About 5 minutes. Any amp with high output impedance is going to show FR deviations when measured into a load other then a resistor. "and it looks to me like Stereophile quit using that testing procedure way back when..." Nope. Here is the same measurement of a Quad II tube amp done in 2005... The Quad IIs output impedance is 1.83 ohms. Remember.... Lumpy frequency response on the neighborhood of plus minus 1 or 2 dB is not typical of home audio amps. Shawn

For Reference: Here is a class A tube 'home' amplifier playing into an 8 ohm resistor then playing into a reactive load. Shawn

"If I can hear it, I should be able to measure it. The test I did for this was, volume adjusted to produce 1 watt then removed the input signal and looked at the output. My test equipment noise level is at about 90 db below 1 watt. I saw nothing above that noise level. Repeated that with gain adjusted for 10 watts. Still nothing. " It may be below the noise floor/range of your instrument. I ran into this when working on the Teac's to lower their noise floor. They had a lot of ultrasonic noise in them and the difference between that noise and the audible noise floor hiss was a wider dynamic range then what my SD-380 could handle. Keeping the ultrasonics below clipping the input into the SD-380 resulted in the Teac's hiss being below the noise floor of the SD-380. Trying to turn the signal level up to 'see' the hiss and I'd clip the input and get all sorts of false readings. I ended up measuring it on my computer which had more dynamic range then the SD-380. Shawn

"That's correct. Which is why I mentioned the brick wall filter. With a sample rate of 44khz, you can't get past the Nyquist frequency. Result: very lumpy response in the passband - as you can see if you magnify Bob's 10dB chart to a more reasonable resolution. If this is impressive for people - fine. It wasn't to me. " That is not at all what I said. There is no reason whatsoever that the Nyquist frequency results in 'very lumpy response in the passband.' That is nonsense, look at CD players (that also are limited by the same Nyquist freqency) and you can find ones that are +/- well under a dB over their bandwidth. Not saying the Crown may or may not show a response like that, but if it does it isn't because of the sampling rate. What I said is anyone that understands a square wave and what the Crown is doing will already know what a 10kHz square wave will look like without measuring it. The Nyquist frequency results in is a very hard upper frequency response limit. If the Crown is sampling at 44.1kHz (possible with a 23kHz top end) then if one plays a 10kHz square wave through it it is going to come out looking exactly like a 10kHz sine wave. And the reason for that is a 10kHz square wave is nothing more then a 10kHz sine wave with lots of odd order harmonics. The first odd order harmonic is at 30kHz which is above the bandwidth of the amp. So all that makes it through is the fundamental sine wave. This isn't of the Crown but the Crown will measure the same wave... bottom trace is the test signal, top trace is the output of the device. Shawn