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4 Bose 901 Series 6's


Guest tony3d

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WOW! I just added a second pair of Bose 901 Series 6's to my exhisting 901 series 6's, and I'm just blown away. Two are up high on towers, and the other pair are on the floor on pedestals. They are in a very large room with cathedral ceilings, and the low end is amazing. I'll take a photo first chance I get. The related components are an Emotiva RSP-2 pre-amp, and a Crown XTI-2000 power amp. Each speaker is getting 400 watts. So far I am very impressed. Don't know how I lived with only two.

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WOW! I just added a second pair of Bose 901 Series 6's to my exhisting 901 series 6's, and I'm just blown away. Two are up high on towers, and the other pair are on the floor on pedestals. They are in a very large room with cathedral ceilings, and the low end is amazing. I'll take a photo first chance I get. The related components are an Emotiva RSP-2 pre-amp, and a Crown XTI-2000 power amp. Each speaker is getting 400 watts. So far I am very impressed. Don't know how I lived with only two.

Can you hear the fan Crown's fan?

I have Bose 901's and I still don't think I have the right amplification for them.

I have an Odyssey Stratos. At 150 wpc it has power but I feel it's a little dark sounding for these speakers.

Did you try different amps?

How would you characterize the sound of the Crown + Bose 901's (2 of them).

I would like to get the 2 901's sounding right before even considering a second pair. Besides, my room is 22W X 20L X 8H.

If your room is much bigger than maybe it warranted 4 901s.

Looking forward to the pictures of your setup!

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Can you hear the fan Crown's fan?

I have Bose 901's and I still don't think I have the right amplification for them.

I have an Odyssey Stratos. At 150 wpc it has power but I feel it's a little dark sounding for these speakers.

Did you try different amps?

How would you characterize the sound of the Crown + Bose 901's (2 of them).

I would like to get the 2 901's sounding right before even considering a second pair. Besides, my room is 22W X 20L X 8H.

If your room is much bigger than maybe it warranted 4 901s.

Looking forward to the pictures of your setup!

No, the Crown's fan has not come on once with for 901'"s playing. Even if it did, I doubt you would here it as it's variable.

My Crown Xti 2000 compared to my Onkyo M504 power amp which has received many excellent reviews over the years, is simply in a different sound league entirely. I have got many direct to disc recordings from Sheffield Labs, and many others that I use as a reference. These albums are in mint condition. One guitar album I have is an especially delicate recording of acoustics guitar.

On my Onkyo M504 the sound is thin, lifeless, boring, and lacks the nuances of a live unamplified acoustic guitar. The Crown opens this recording wide up, giving it the vibrance and attack that a good acoustic guitar recording is capable of. Bass passages on the Crown deliver the impact, and punch my Onkyo delivers as muddy, and boomy sounding.

Now I'm comparing a Crown Xti-2000, I have no idea what other current Crown amps sound like, as I have no experience with them, but this amp compared to my Onkyo M504 is superior sounding in every way. When I had bought my Onkyo I payed $899.00 for it. It lasted about 9 years. This Crown cost me $699.00. It would be a steal at twice this price. I am now interested in learning what other pro amps in Crown's line sounds like. It could very well be that this new amp sounds much better than there other amps, I don't know. 5 years ago I would have never considered buying one of these pro amps. Today I can't imagine spending four or five times the amount on a consumer amp. I go with my ears and they have been listening to live unamplified jazz for many years. I'm more that pleased with the results. So much so I will probably never look back. I'm sorry but that is the acoustic truth as I hear it. The only amp I have owned in the past that approaches this sound quality was my Harman Kardon Citation 16. I think we would all agree that was a fine sounding amp.

Go for the Crown. You won't be disappointed. By the way my room is 36 X 29 feet. I'll post a picture soon.

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  • 2 months later...
Speakers located that way certainly will deliver a room-filling and extra-large soundstage image. With most pop music this will be impressive and enjoyable. With classical and jazz the soundstage will not be particularly realistic, however. Live-concert, acoustic-instrument ensembles do not present that kind of amorphous image.

Your room is so large that it is no surprise that the Crown has an edge over the Onkyo, at least at seriously high playback levels. It is likely that the Onkyo is simply clipping, which could result in any number of negative artifacts being audible. In a smaller room, or at gain levels that do not have the Onkyo clipping, the two amps would sound identical, assuming that neither is defective. People make much too big a deal out of so-called amp "sound." If an amp playing within its output design limits is coloring the sound it was either designed by somebody who was incompetent (and I doubt if the Onkyo engineers are that way) or else it is defective.

When comparing amps, it is MANDATORY that the levels on each channel be matched from unit to unit to perfection. While a digital volt meter and test signal is the best way to this, one can get decently close by simply using pink or white noise and their ears. If this is not done and the levels are not matched, any comparison is going to be very problematical. Once the levels are precisely matched, comparing will be even more bulletproof if the work is done blind, or better yet, double blind.

Howard Ferstler

The factors that influence the way a particular amplifier will cause a given speaker to sound are many. The basic theory behind testing amplifiers for frequency response, non linear distortion, hum and noise, power output, etc. is correct. The problems stems from the fact that the conditions customarily used to test amplifiers do not correspond to the way they are used in the real world. For example, it is customary to test an amplifier on a test bench with an 8 ohm and a 4 ohm resistive load at one watt output, at least for its frequency response. A variac assures the power input voltage is exactly 120 volts. In the real world, this is hardly the case. Loudspeakers are not resistive loads by a long shot, in fact they are not even passive loads. And line voltage can vary often by at least several percent. In all fairness, this kind of testing showed the significant and meaningful differences in amplifiers say 60 or 70 years ago when signal bandwidth was limited and variations so high within the constraints of these tests, you could often distinguish one amplifier from another by this method alone. But things have changed drastically.

One of the major factors in amplifier performance is the power supply. This is often one of the important differences between so called "professional amplifiers" and consumer amplifiers. The ability of the power supply to maintain the quiescent operating voltage the signal transistors (or tubes) were designed to operate at is key. Good amplifiers have well regulated power supplies that compensate for these real world factors of input power voltage and difficult loads. Many low to moderate cost consumer amplifiers do not. Regulation consists of at least three general types, input, output, and brute force. Input regulation is the ability of the amplifier to maintain the correct output voltage over a range of power voltages from your wall outlet. Ordinarily, if the input to the power transformer increases or decreases, so does the output voltage. Output regulation is the ability to maintain the correct output voltage under a variety of conditions such as high current flow to the speakers and voltage kickback (reverse emf) from the loudspeaker. Brute force regulations refers to the maximum design load the amplifier will be used to support being a fraction of its true capability. This usually requires the use of large and consequently expensive transformers and lots of filter capacitance. Electronic regulator circuits also play a role in maintaining output voltage. The faster the power supply can react to difficult load conditions that tend to alter its output voltage the better.

An example of how a loudspeaker can affect the performance of an amplifier can easily be seen by applying a 100 hz square wave to the input and connecting the output to an oscilloscope. With no load, the square wave should look quite flat and level. Add a resistor and it may tilt slightly. Connect a speaker instead and you will see a visible tilt of the wave towards the trailing edge. The greater the tilt, the greater the speaker is pulling down the power supply voltage and the less output there will be. And sign of ringing (the waveform not being a straight line) means more trouble. For a DC coupled amplifier with zero output impedence (the ideal case) the tilt will be zero. Output impedence is often directly related to power supply regulation, the lower the better. The problem causing tilt is the high inrush current on each half cycle of the inductive load the speaker presents. As bad or worse is the reverse emf the speaker generates. All electromagnetic motors are also generators and a dynamic loudspeaker is nothing more than a linear electromagnetic motor. The reverse emf is the kinetic energy stored in the driver being reconverted to electrial power. The lower the power supply impedence, the faster this power will be dissipated as heat in the outupt devices and the power supply itself. The principle is used for what is called dynamic breaking of large electrical motors, that is in addition to the friction brake, stopping a motor from turning can be improved by short circuiting its armature. This is what amplifier damping does. High output impedence whether inherent in the amplifier or the series resistance of the wire delays this dissipation and allows the speaker to produce audible spurious sounds principally at its natural resonance frequency. Inside the amplifier the applied reverse emf adds and subtracts to the power supply voltage causing the quiescent operating point of the transistors to oscillate. This can cause distortion. There are other factors which make one amplifier sound different from another that don't show up in traditional tests or specifications.

Insofar as Crown amplifiers are concerned, they are among the very best amplifiers availabe at any price and their low cost is remarkable. Anyone who needs a reliable high powered amplifier would do well to consider buying one. If you don't like the way it makes your sound system peform, look for the problem elsewhere, it won't be due to the amplifier.

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  • 11 months later...
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I also added a second pair of 901's to my current set-up and was very pleased indeed. I had previously been using a pair of nice (but not 901 level nice) Yamaha's in the back for that 5.1 surround effect. That was ok when watching a movie, but when I would listen to music, their "direcctness" as compared to the 901's "spaciousness" was very noticeable and annoying to say the least. By adding a second pair for that end of the room, it was a night and day difference. With my eyes closed, I could no longer locate the speakers in the room. The sound is everywhere and equally distributed. And of course I think the quality of the sound is much improved also. Now at last I can lay into the volume on the big, fat Denon and not hear the rear speakers knocking themselves to pieces. As a matter of fact, I sometimes can't hear myself think… which is a relief sometimes. Some music just demands to be felt as well as heard. Good thing I own the house next door too.

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