My New Crown XTi 1000s Are Here!!

[mikebse2a3]

OK, I heard some noise, but less than others report. I think Mark reported more noise than I heard. Is it possible that we all need to look upstream of the XTi 1000 to find the noise. I used probably less equipment than others and heard less noise.

What do you guys think?

Bob

Hey Bob

I believe the best way to test for the amplifier's inherent noise floor is to short (or place a reasonably low input impedance to the input of the amp) the input of the amp and look at the amplifier's output noise level. Any increase in noise from this reference measurement could then be the result of a system's upstream componets noise floors, gain matching issues, impedance interactions and ground point interactions between componets.

mike tn[]

[BEC]

OK, I heard some noise, but less than others report. I think Mark reported more noise than I heard. Is it possible that we all need to look upstream of the XTi 1000 to find the noise. I used probably less equipment than others and heard less noise.

What do you guys think?

Bob

Hey Bob

I believe the best way to test for the amplifier's inherent noise floor is to short (or place a reasonably low input impedance to the input of the amp) the input of the amp and look at the amplifier's output noise level. Any increase in noise from this reference measurement could then be the result of a system's upstream componets noise floors, gain matching issues, impedance interactions and ground point interactions between componets.

mike tn

Mike

That is what I was saying I did. The noise from the amp is at least 90 db down from where 1 watt would be.

Bob

[BEC]

Mark said "Secondly, I connected the output to an 8 ohm resistor, shorted the input and looked at it on the 'scope. I saw 200mV of broad spectrum noise."

Mark,

Like I said earlier, don't have access to my scope, but I did that same test using my true RMS DMM. Read 0.0000 VAC. The DMM claims to be good to 20 khz.

Bob

[mikebse2a3]

BEC said:

My son Michael is younger and has more sensitive ears than I. He could hear the noise at 3 inches from one tweeter and around a foot from the other tweeter. Neither of us could hear any noise at a normal listening distance.

Mark said:

I didn't have ANY "upstream" equipment. I just shorted the input and listened to the output on 96dB speakers. The noise was audible from my listening spot about 8 or 10 feet away. Didn't bother me that much, I just noted it as an unusual thing. My Mac had no such noise, my new D45 has no such noise.

OK this is why something doesn't add up about the Crowns.

BEC do you estimate your cornscala to be about 100db efficient? If so then you and Michael should have heard the noise much worse than Mark with his speakers around 96db efficiency and heard noise 8'-10' away.

Now if I remember right Mark1101 reported noise at a similar distance of approximately 10ft.

The amps that BEC has now are Mark1101's amps correct? So they were very noisey in Mark1101's setup but not noisey in BEC's setup. Sure sounds like some system interaction issues being a possible cause in Mark1101's case anyway?

mike tn[]

[BEC]

Yes, 100 db is about the efficiency of the Cornscalas. More specifically, I guess we could just talk about the tweeter we were listening to. It is 104 db attenuated by 3 db, so 101 db.

And yes, I have Mark1101's amps.

Bob

[mark1101]

I'll repeat. I could clearly hear a loud hiss the length of my 26 ft. room. There was nothing connected to the input of the amp. Just the speakers. The hiss came out of the 402 horn. If my room was 10 ft. longer I would still have been able to hear. it. Hmm. I recall a place I heard Jubs and had to ask where the horrible hiss came from. Mine was just about that loud. I find it peculiar that I heard it in two places, one being my home.......but everyone else can't replicate to the same level.

[BEC]

I'll repeat. I could clearly hear a loud hiss the length of my 26 ft. room. There was nothing connected to the input of the amp. Just the speakers. The hiss came out of the 402 horn. If my room was 10 ft. longer I would still have been able to hear. it. Hmm. I recall a place I heard Jubs and had to ask where the horrible hiss came from. Mine was just about that loud. I find it peculiar that I heard it in two places, one being my home.......but everyone else can't replicate to the same level.

Mark,

Did you ever try the amp with DSP off just using it as an amp? If I remember right, the K-402/K69 is around 107 db and the settings for the Jub with K402/K-69 provide a lot of boost on the top end.

Bob

[mark1101]

Bob, what I found was that changing the DSP settings had no effect on the hiss. I remember that. The volume controls and DSP didn't change it at all. It was always there with the amp on. Both amps sounded exactly the same to me.

I'm sure of this. I disconnected my entire system to trace it......and found the amp and speakers alone still did it.

I now have my Scott LK-72 connected with passives and there is a tiny hiss and buzz that that amp always had no matter what speakers I connected it to. But it is pretty tame. What I would call the normal tube noise I always used to hear.

[Islander]

The high sensitivity of the K-69 tweeters will let hiss come through that won't be evident with other speakers. I've dealt with some noise issues with my Yamaha amps, which are fairly quiet, yet the K-69s produce a hiss, while the CT125s did not, when being powered by the same amp.

When I showed the tech from the local pro audio shop some pictures of forum members' setups with XTi1000s, he commented that they were not the quietest amps he'd dealt with. They're good value, but you can spend more and get less noise to go with the music.

[mark1101]

This hiss is no mystery. Just go to the Corwn forum. When I first bought the amps and discovered it I went to the Crown forum to see if others reported it. There were several reports. Go read them.

[mark1101]

I just went to the Crown forum and the very first post is a rfesh complaint about hiss on an XTI 4000. Read some of the others comments in that thread. Look at some of the other threads too.

[Deang]

Bob, remember, the DSP is "on" whether it's on or off. The noise level from the horn stays the same regardless of how you manipulate with PEQ or attenuate the input level. You can attenuate the input signal 60dB and the noise level from the horn stays the same. The only way to make it going away is to click "mute" or turn off the amp.

Basically 6dB difference between a CornScala and a Jubilee -- that's quite a bit. Several other factors might contribute in how that noise level is perceived; noise floor of the room, how live the room is, and of course individual hearing.

JC has the amp Mark Deneen had, and on his LaScalas can barely hear it, yet we get the sense from Mark that it was a bit obnoxious when he had it and he doesn't even have a tweeter -- go figure. I can barely hear it either, so maybe JC and myself have some HF hearing loss, I simply don't know how else to explain it. OTOH, I thought the setup Mark1101 is referring to was pretty noisy myself, but I'm just not hearing it that way over here. I gotta say though, if I could hear that noise from 26 feet away I would have dropped kicked them to the curb the day after I bought them.

[NOSValves]

I gotta say though, if I could hear that noise from 26 feet away I would have dropped kicked them to the curb the day after I bought them.

Me thinks if you could truly hear them you would drop kick them to the curb []

[SWL]

"if I could hear that noise from 26 feet away I would have dropped kicked them to the curb the day after I bought them."

Agreed.

[NOSValves]

As far as the noise goes this could be very much house/neighborhood AC related. Maybe these little babies are very susceptible the noise from the power grid......

[Deang]

The high sensitivity of the K-69 tweeters will let hiss come through that won't be evident with other speakers. I've dealt with some noise issues with my Yamaha amps, which are fairly quiet, yet the K-69s produce a hiss, while the CT125s did not, when being powered by the same amp.

When I showed the tech from the local pro audio shop some pictures of forum members' setups with XTi1000s, he commented that they were not the quietest amps he'd dealt with. They're good value, but you can spend more and get less noise to go with the music.

I think they're very good performers if you use them the way they were primarily designed to be used -- active filtering with multiple amps. They work good on Roy's big horn, and I think they sound clean and detailed without hyping up the top end. A little bit of noise at idle, which you don't notice once the music or movie starts. They have a commanding midrange presence which will inflict a great deal of pain at higher SPL's with poor recordings. The image is more two-dimensional than I'd like it to be -- but I've never heard any solid state that can get the sound out into the room like a good tube set up can. However, the big horn does an admirable job in helping to offset that. If you want PK's and Roy's last stand, and find your checking account dipping down into the red -- a couple of these amps will get you up and running for $850 more and leave you with very little to complain about.

[Deang]

As far as the noise goes this could be very much house/neighborhood AC related. Maybe these little babies are very susceptible the noise from the power grid......

Interesting -- mine are patched into a Furman AR1215.

[Deang]

I gotta say though, if I could hear that noise from 26 feet away I would have dropped kicked them to the curb the day after I bought them.

Me thinks if you could truly hear them you would drop kick them to the curb

Well, Al always did tell me I like the sound of distortion, and Bob says I hear what I want to hear.

[BEC]

I have to run off to get my beauty sleep. But, I think it is time to re-ask the question that I must have stated poorly before. If as my measurements indicate, noise from the Crown is at least 90 db below 1 watt, how do I or anyone else hear it? Since one watt would give me about 100 db., to hear something at least 90 db beolw that sounds impossible to me. A very quiet room is probably 30 to 40 db. I think someone told me that our own heartbeat is about 25 db.

Bob

[mikebse2a3]

I have to run off to get my beauty sleep. But, I think it is time to re-ask the question that I must have stated poorly before. If as my measurements indicate, noise from the Crown is at least 90 db below 1 watt, how do I or anyone else hear it? Since one watt would give me about 100 db., to hear something at least 90 db beolw that sounds impossible to me. A very quiet room is probably 30 to 40 db. I think someone told me that our own heartbeat is about 25 db.

Bob

OK I'm about all thunk out for today myself!

As far as the room noise floor I guess that depends on what frequencies the room noise floor is. Never really thought about it that much but logic would dictate that the room noise isn't high enough in frequency and level to mask the HF noise being heard from the amp/speaker.

mike tn[]