Measuring Amplifiers - Page 26

+



Chest thumping is centered around 70hz, therefore no lies there
Subharmonic Synth?


http://www.crownaudio.com/pdf/amps/139472.pdf

BTW, just hit me, the DSP is off? It looks like its a 4dB HPF, or a -4dB PEQ low Q.

Exojam, Im actually with you!! I have several of the amps here that have been HAMMERED by the tests and I still use them knowing that I love the sound STILL. Although Im still thinking there is something more to the Xti test...no way it only has that many Watts at 20Hz...

Anyways, I did pick up a second SC-1250 and I will have that tested if it works out well then I might replace all my amps with the Velodyne SC-1250...RCA connects, no fan, nice home audio rich look (not the normal PRO amp ugly stuff), REMOTE CONTROL!!!



I hate you dammit, I just hate you...I like the 1000W per side @ 2 ohms for $200!!! Heck that is cheap enough to just buy and send to Chuck....Chuck I hope you are not to busy

Here is another amp I found today....Marathon MA-5050 1900 Watts Per Channel 4 Ohm DJ Amplifier for $750 (- Output Power 2 (ohms): 2 x 2500W, Output Power BRIDGE 8 (ohms): 3600W, Output Power BRIDGE 4 (ohms): 5000W )

lots of amps out there too buy and test

Chuck,
mabey HiQnet System Architect 1.7 will give you easier control of the XTi over usb

http://hiqnet.harmanpro.com/sa_download.php

Thy,

I don't see how the sound between those frequencies (35hz - 100hz) would be inaudible between the Buttkicker and the XTi. The Buttkicker measured 14% distortion at 50 HZ. All I did to hear the difference in music was to play something I listen to on a regular basis, cranked it up and sat right next to the sub and could tell the difference.

Crown ...you better answer.

I am not going to give this 90W monkey business a rest until this is either solved or I return my amps and exchange them for something else.

Tomorrow I will run test tones,at very high SPL. Lets see how TC-3000 react.Lets see what Clown Inc has in the tank.

Please do.

Looks like more QSC PLX II for TheEAR....

Looks like Clown will have alot of clowning to do to come out of this.

I never knew I had three Clowns R Us amps !

Its a powerful performer for HEADPHONES ! I could not even damage in ear drivers with this much output at 20hz.

You could always build a tweeter array......

I am going to do better...an altar of Shame and Clown will be the guest of dishonor.

lets wait and see if there are any filters still set or if something else is wrong.

lol, I already have it in a shopping cart.. I can not resist a $200 amp with specs on paper like this.

EDIT: I decided to buy the Samson PG3800 because its only $360 shipped and if it only does half of what it says it will drive my IB array very well. (The PG3800 offers up to 3800 watts of power bridged mono at 4 ohms and 1800 watts per side at 2 ohms.) The PLX3402, XS1200 and XTI4000 are the other amps with those posted specs.....For $360, I doubt it comes close to those, except now the XTi one is probably questionable.

I corrected my post to read "20 msec". My bad.

That may be a point to check out. The amp front panel and DSP can be locked using the HiQnet system and (that) cannot be released with the front panel display.
Chuck, did fireanimal have any presets in the DSP? If he did was there a Frequency response curve installed looking like the result we're trying to analyze on your test result?
And the last excuse . . . . . if UPS DID drop the amp and/or bounced it hard enough to dislodge the fuse from it's holder could there be some damage to the unit?
In any case I think the amp should be sent to crown for analysis.

Most excellent!

I'd say even if it can do 75% of those numbers on Chuck's test, its a darn good buy. You'll have to start a thread on it, post the full manuf. specs (can't find them anywhere), and tell us about the fans, etc.

I'm referring to only the XTI, < 35hz vs. > 35hz playback. I don't know
what your system is or music.

Tapco Juice J-2500 is on sale for $299 shipped at MF.

"All readings were taken with a THD set between 0.475% and 0.5%. "

That could be it right there.

Maybe the Crown will produce its rated power at 20 Hz, but with much higher THD, in which case it would be easy to believe it could go unnoticed.

So the question is, at what power does it actually hit the voltage rails?

The reason that I don't think that there are any filters set is the distortion on the measurement. Chuck took the measurements all at close to .5% THD. If the DSP was on with a filter of some sort you wouldn't really expect the distortion to jump as a result, would you? Even with a filter set, it should still get pretty much the same power output in this test. This was a test up to a distortion limit, not the front panel gain limit.

If it were a filter issue we would see a drop off in the 8 ohm measurements as well, in which we don't. I highly doubt there is a 4 omm only filter.

did this happen?

though i already bought a Behringer EP2500, i'm curious about this amp.


can someone do a running graph of these tests?

yes i'm pushy.

super thanks chasw for doing all the hard work.

Thy,

Sorry, I misunderstood what you were referring to.

So, no DSP, everything cleared. Got that out of the way...
I'm so stupid, if there really was a DSP filter then it would have affected 8 ohms 20Hz too anyway. Well at least 8 ohms is running 20Hz a-ok, so 8-ohms drivers are ok as long as the impedance dips do not get too low.

If something is indeed faulty in the amp, is it probable that both channels are affected simultaneously? And to the same degree both channels, as far as power is concerned? I'm not an expert, but my guess is no.

Just 2 weeks ago I nearly wanted to get this amp too as the DSP is good and convenient. But something pulled me back when another forumer told me there is "NO CONTEST" (his exact words) when he compared between the XTi2000 vs Face Audio F-1200TS (old school design). He tried everything from DTS-20 to growler, 1 per channel, 2 per channel, bridged, high level volume and even low level volume. Not as tight...No Contest, yada yada. He thought that the Face Audio was a mistake and wanted to change to the XTi so was trialing it. Together with some pro users who used it for sub duty saying that they did not like the low freqs (together with the Yamaha flagship P7000S). That did it for me....

Who has an I-tech?

Very good observation and also what I suspect.

Maybe with 2-3% THD it can get closer to spec,not meet spec(as it does not meet at 1KHz either).


The can O worms is open,Crown better step in and explain this poor performance.


I will calm down and run some heavy test tones on TC-3000 sealed 15's ,it will not go very far with 90W if true.

Hasnt happened yet, I have two SC-1250s and they are being used for my own in room measurement tests once Im done with that, I will send one off too Chuck.

Im hoping to ship it Monday or Tuesday.

Couldnt we say this about the Dayton 1000W test too? I didnt see anything about the set THD but we could use higher THDs to get closer to the specs?