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Thread: Holy Crap!

  1. #41
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    Quote Originally Posted by audibleconnoisseur
    Yes, I know about the SPL, etc. What I was getting at is that the 2807 was able to play louder at the -15dB than the 1907. This, to me, said the parts/circuitry/audessy system insides were better or the amps were higher or both. this to me meant that you could technically play them louder with more headroom! that was all but I wasn't sure at the time.
    Hi Audible,

    I think you are missing the point I have been trying to make... If the 2807 sounded better, that is one thing. The fact that it played "louder" at -15dB on the volume contol means absolutely nothing. Current (amperes) is a function of voltage and impedance. If neither receiver was approaching the limits of their current capabilities (and I am sure they were not) -- if they were both delivering the same amount of voltage into the same loudspeakers, they were both producing the same amount of current (for ANY amp / receiver). If one receiver was louder than another at the same volume control level, that receiver was delivering higher voltage, meaning that receiver has higher gain and because of the higher voltages, would be producing more current.

    Voltage = how loud it is.
    Current = how load it CAN get and how much headroom.

    You can not audibly determine how much headroom an amplifier has unless you are listening at a loud enough level where there is audible clipping or compression. At the same output level (not volume control setting) into the exact same loudspeakers (must be the same impedance) if one amp begins to distort and sound compressed while the other still sounds clean, the cleaner sounding amp has more headroom === more current capability === more "power". This procedure is the only possible way to make this generalization without taking measurements.

    I believe you are confusing gain (voltage) with power... Please read my examples again.. I have explained the concept as clearly as I am able -- difficult for me to put concepts to words sometimes..

    I think perhaps you are assuming that the overall volume of the system will keep increasing as the volume control knob gets higher and higher... It won't, you will hit the maximum current capability of your receiver well before you "turn it all the way up"---- Think of the accelerator pedal on a car example.... the speed of the car in reference to the position of the accelerator pedal = gain (amount of voltage being delivered). It is completely unrelated to what the top speed of the car is or how fast the car can accelerate (power).

    If you test drove 2 cars -- car 1, you pushed the accelerator down 1/4 and went 50mph -- car 2, you pushed the accelerator down 1/4 and went 30mph... In your example, you would be assuming car 1 has a faster top end speed. You can't draw that conclusion from this premise... At least in an older car, all I would need is a wrench and pliers to make car 2 go 80mph or 10mph at ¼ pedal position. In a receiver, a soldering iron and a few resistor changes – in a car, my “modification” has no affect on the capability of the engine -- in a receiver, my modification has no affect on the capability of the power supply. Hey – this is a good example, I think?

    Perhaps someone else can explain it better? Where is LeeBailey when you need him

    AleksB - you get it
    Last edited by davef; 01-25-2007 at 10:54 PM.
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    Good Sound To You!

    David Fabrikant
    www.ascendacoustics.com

  2. #42
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    Jan 2006
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    Default Good morning Dave!

    Yes, I get it and I think I provided an incorrect argument but your message a few posts back about this and via the phone the other night were CLEAR and I know something was incorrect. Please don't think me slow or incapable of comprehending what you are saying, as I do

    I know that what I heard and saw were different and I will get to the bottom of it when I can return there to retest the same speakers, as well as test on my own. Not to rehash or ask for another explanation (btw, all of your explanations were VERY clear to me, especially the water in the pipes as I used to be a loss prevention consultant with FM GLOBAL) but my arguement and comments were that @ -15dB on both, I heard much louder sound coming from the same speakers with the 2807. That led me to the questions prior about why and how so I was trying to educate myself as to why or how. I first thought that with this test, if I pushed the 2807 to -5 or 0, it would have been MUCH louder still than the 1907 at the same level so there must have been more power/current/amps. I now know that there is a fallicy in the thought process but it was a good thing to happen b/c now I know MUCH more about this than I did a week ago, thanks to you and the others on here offering their input.

    I did consider the 2807 b/c it could play louder at the same perceived volume level on the dial but now I know better what to look for when I test this weekend and next week. I will use the SPL and the volt meter as you suggested, hopefully without having to call you, and put some thoughts down when I am comfortable with them.

    Thanks Dave, for your CONTINIED and PROFESSIONAL support. I really am not unintelligent, quite the opposite with IQ above MENSA level - however, ignorance will kill you and this is why I ask so many questions! Thanks again to all for your input!

  3. #43
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    That is a pretty good analogy.

    Here's a break-down of how it works:

    Lets start by assuming you have a separate amplifier and pre-amplifier (if you decided to use an external amp with your Denon, this would be your situation), and you're using the analog outputs of a CD player as your source (to keep it simple). Our speakers are 8ohm.

    In both of these cases, gain is literally a multiplier - it increases the voltage by a certain factor (like 6 times).

    An amplifier has a few properties: gain, max power output, max current output (there are more, but we'll stick to these). All three of these items have exact values that you can measure and are always the same for a given amp - lets say our amp has a gain of 7x (usually measured in db, but that's more confusing for our discussion), a max power output of 60W per channel into an 8ohm speaker and a max current output of 3A per channel.

    A pre-amplifier also has a couple of properties: gain and attenuation (volume control). Lets say our pre-amp has a gain of 3x. The attenuation is variable since it's the volume knob.

    A CD player basically has a fixed output of so many volts, we'll assume 1V for this example. (Obviously the voltage is lower during quiet passages of music and higher during loud ones, but we'll just pick one level for the example).

    So, what happens when you play music??

    A CD player is kicking out a 1V signal to the pre-amp.

    The preamp does two things, it reduces the level through attenuation and increases it through gain. This seems very strange, but think of it like an engine that is always going at the same speed and the only way to slow the car down is to use the brakes. For this example, we'll assume our volume knob brings the level down to 0.7V, then the gain brings it back up to 2.1V and passes this to the amp.

    The amp also has a gain and increases the 2.1v to 14.7V which it passes on to the speaker. An amp applies the same multiplier to all incoming signals, it's just a voltage increasing box. With an 8ohm speaker applying 14.7V requires 27W of power per channel, meaning that the amp has to be able to put out 1.8A per channel. Our amp can pull this off (our amp hits its limits right around an 8ohm speaker at max volume with this pre-amp and CD player).

    If we hooked this same combination to a 4ohm speaker, reaching 14.7V would require 54W and 3.7A per channel, exceeding the current capabilities of our amp. For this reason, high current output amps are most important when you have speakers that have a lower impedance.

    How 'loud' things get at a particular voltage is determined by the sensitivity of the speaker. In the example above, if both speakers had the same sensitivity, they would be equally loud at the same volume knob setting, but the 4ohm one would be eating up twice the power.

    In short, 'loudness' is only a factor of voltages (output of source, attenuation and gain of pre-amp, gain of amp and sensitivity of speakers) and the back end requirements to meet those demands are met by the power and current capabilities of the amp.

  4. #44
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    Jan 2006
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    Default Here's what I know

    Hey, they sound damn good! They are build well and solid! They were very reasonably priced for my needs! Dave and the crew are top notch at support and helping the "little guy" know more! They could use a refresher look sitting on the bookshelfs, but the sound is what is important!

    I also know that I am getting mine in about 2-3 hours and will be leaving work early to bring them in from the cold and set them up properly to break them in well. I know I can't wait so I am taking a 1/2 day! I know that I have researched what I can and past what I needed to for the best I could find in my price range and know that I have compared them to $500, $600, $800, $900 and $2100 sets of both floor and bookshelf speakers and also that they outperform all of them. Are they the best out there? This depends on who you ask. For me, my needs and wants and budget, they are and I came to this conclusion from MUCH research given to many sets of speakers (10+ sets) and time spent talking with Dave, James, and all of you out here with your collective knowlege. Only thing left to do is break them in, test them with different receivers to find the best sound and features for my ears and our needs and hook everything up and enjoy!

    You guys out here are awesome and I appreciate all of you that have provided your input for my/our benefit. Much respect to you all - I will still be around often though since I work on a computer much of the day! Cheers and Ciao ~

  5. #45
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    I don't know if your receiver has pre-outs, if it does and you like its' feature set; you might give the idea of buying an amp and using your receiver as a pre/pro instead of another receiver some thought.

  6. #46
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    Default BradJudy

    Would it be safe to say that most receivers would be high current.

  7. #47
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    Quote Originally Posted by leon55
    Would it be safe to say that most receivers would be high current.
    No, that isn't a safe statement. The best way to see if they are higher current is to see if they officially support 4ohm speakers (for example, H/K says their receivers are fine with 4ohm speakers).

    Another popular method is the pure weight of an amp/receiver. Since the largest single source of weight in an amp/receiver is the transformer(s), it is an indicator of current capacity. This measurement isn't exact because other things add weight (heat sinks, chassis, etc) and it doesn't work well with class-D options that are much more efficient, requiring smaller transformers and heatsinks.

  8. #48
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    It still seems as though there is some confusion as to the "overall volume level," in this case -15 (from reference, because I'm sure the store properly calibrated) and indivudual gain settings for each channel. I'll take a more simplistic approach and see if this helps (and I do apologize if you understand).

    Both receivers were set to -15 at the main volume setting. In the set up menu for each receiver there will be additional "volume" (actually referred to as gain) settings for each individual channel (or speaker and typically referred to as "channel level"). The 1907 may have had the individual channel settings at "0" where as the 2807 had it's individual channel settings to +6, thus the 2807 sounded louder and more powerful. What everyone has been trying to say is to look into the setup menus of both receivers and see what the "channel level" is set to for both...chances are the 2807's will be higher than the 1907. This is where Dave's pipe analogy comes into play (the 2807 would be using the 2" pipe, and the 1907, has been restricted to a 1" pipe).

    Not trying to beat a dead horse and again I apologize if I'm oversimplifying.

  9. #49
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    Jan 2006
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    259

    Default i know

    i did this and i am telling you that all things were equal except what i didn't see on the computer screen he was controlling. this is why i have the 2807 in my home to test b/c i won't lie or cheat myself! i appreciate your input but the test has to be performed by me to know for sure! i will let you all know this or next week when i have the guys back over to test them...

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