| Home |
| Search |
| Today's Posts |
|
#1
|
|||
|
|||
Using a surround receiver for tri-amping?
Is it possible to use a modern 6.1 or 7.1 home-cinema receiver for
tri-amping a classical stereo setup? (I have never owned such a receiver, so I am just speculating) I realize I may need to hook in an outside 3 way crossover. If the answer is receiver-dependent, I am thinking of using a Yamaha RX-V750 (not yet purchased). Any suggestions? |
|
#2
|
|||
|
|||
|
"RLS" wrote in message
Is it possible to use a modern 6.1 or 7.1 home-cinema receiver for tri-amping a classical stereo setup? Some yes, some no. The lower-priced ones generally lack 5, 6, or 7 channel analog inputs. I realize I may need to hook in an outside 3 way crossover. The obvious choice for that would be the Behringer DCX-2496 ULTRA-DRIVE PRO If the answer is receiver-dependent, I am thinking of using a Yamaha RX-V750 (not yet purchased). Any suggestions? Look for those analog inputs! A picture of the back panel may clarify the situation. |
|
#3
|
|||
|
|||
|
In addition to what AK said...
Most multichannel amps have identically powered channels. But you should check the spec sheet closely to see if there's any difference. For example, if you think you need, oh, 100 watts to drive the woofer, and the amp has only one 100W output, then you'll need to look elsewhere. Oh, yes, another thing (mimicking Peter Falk)... If you intend to use the subwoofer channel, make sure that it doesn't have a crossover of its own, or if it does, that it can be switched off, or set to a much higher frequency than you intend to use. |
|
#4
|
|||
|
|||
|
RLS wrote:
Is it possible to use a modern 6.1 or 7.1 home-cinema receiver for tri-amping a classical stereo setup? (I have never owned such a receiver, so I am just speculating) I realize I may need to hook in an outside 3 way crossover. If the answer is receiver-dependent, I am thinking of using a Yamaha RX-V750 (not yet purchased). Any suggestions? Probably not without surgery. But there are some multichannel _amplifiers_ that are made for the home theatre market that you might look into. Parasound makes a decent one. You add a preamp and a crossover and you are good to go. --scott -- "C'est un Nagra. C'est suisse, et tres, tres precis." |
|
#5
|
|||
|
|||
|
I agree that the idea is messy. Amy Krueger (above) says it is
possible with some receivers. If money was no object, I wouldn't try this gymnastics. The probleme is that the [preamp + tuner + Parasound amp] solution is at least 2 or 3 times the price of a "decent" mass-market home theatre receiver. In France, where I live, the price differential is even more dramatic. (You wouldn't want to transport a power amp back and forth across the Atlantic, for service - say) --ramez =============================================== On 28 Jun 2004 09:19:13 -0400, (Scott Dorsey) wrote: If the answer is receiver-dependent, I am thinking of using a Yamaha RX-V750 (not yet purchased). Any suggestions? Probably not without surgery. But there are some multichannel _amplifiers_ that are made for the home theatre market that you might look into. Parasound makes a decent one. You add a preamp and a crossover and you are good to go. --scott |
|
#6
|
|||
|
|||
|
RLS wrote:
I agree that the idea is messy. Amy Krueger (above) says it is possible with some receivers. If money was no object, I wouldn't try this gymnastics. The probleme is that the [preamp + tuner + Parasound amp] solution is at least 2 or 3 times the price of a "decent" mass-market home theatre receiver. Yes, but it doesn't sound like crap. You just cannot believe how awful most of the mass-market home theatre gear is. In France, where I live, the price differential is even more dramatic. (You wouldn't want to transport a power amp back and forth across the Atlantic, for service - say) So look at used amplifiers out there. Start out with two channels, then add on. The cost of a good crossover is going to cost you as much as the amps in some cases, anyway. --scott -- "C'est un Nagra. C'est suisse, et tres, tres precis." |
|
#7
|
|||
|
|||
|
|
|
#8
|
|||
|
|||
|
In article ,
RLS wrote: On 28 Jun 2004 13:59:09 -0400, (Scott Dorsey) wrote: So look at used amplifiers out there. Start out with two channels, then add on. The cost of a good crossover is going to cost you as much as the amps in some cases, anyway. I am new to this area (bi or tri-amping.) I thought I would start experimenting with the Behringer "Super-X Pro CX3400" 3-way stereo crossover, which is very affordable (haven't bought it yet). Does that sound like a poor choice? Yes. --scott -- "C'est un Nagra. C'est suisse, et tres, tres precis." |
|
#9
|
|||
|
|||
|
|
|
#10
|
|||
|
|||
|
RLS wrote:
On 28 Jun 2004 14:45:45 -0400, (Scott Dorsey) wrote: I thought I would start experimenting with the Behringer "Super-X Pro CX3400" 3-way stereo crossover, which is very affordable (haven't bought it yet). Does that sound like a poor choice? Yes. What is your candidate for a "basic", good 3-way crossover (for musical/hi-fi listening)? Well, the Rane AC-23 is minimally acceptable. I wouldn't want it in my home, but it's certainly better than the usual range of PA junk. It could certainly be cleaned up a lot inside. In a home installation, though, I would really worry whether something of that grade would be any better than a passive crossover. Unless you are going to go up to the Sumo/Perreaux grade of gear and go with a decent high grade amplifier set, I would think you'd be a lot better off for the dollar going with a clean full-range system. --scott -- "C'est un Nagra. C'est suisse, et tres, tres precis." |
|
#11
|
|||
|
|||
|
|
|
#12
|
|||
|
|||
|
In article ,
RLS wrote: On 28 Jun 2004 15:12:52 -0400, (Scott Dorsey) wrote: Well, the Rane AC-23 is minimally acceptable. I wouldn't want it in my home, but it's certainly better than the usual range of PA junk. It could certainly be cleaned up a lot inside. Do you categorize the whole Behringer line as "PA junk" ? The Behringer gear that I have used, and I admit it is a pretty limited amount, was not good enough to be considered "PA junk." How about the DCX2496 Ultra-Drive ? Or (to compensate for room modes) the DEQ2496 used as parametric eq / notch filter? Why would you want any of this stuff? Notch filtering is a terrible kludge that people do when they only have a short setup time and can't fix the room modes. There's no reason do that in the home system. Why do you want to put all this crap in your signal path? You will do much better to have as simple and direct a path as possible, especially if you are on a severe budget. One channel that sounds good beats eight that sound bad, any day. --scott -- "C'est un Nagra. C'est suisse, et tres, tres precis." |
|
#13
|
|||
|
|||
|
Arny Krueger wrote:
"RLS" wrote in message Is it possible to use a modern 6.1 or 7.1 home-cinema receiver for tri-amping a classical stereo setup? Some yes, some no. The lower-priced ones generally lack 5, 6, or 7 channel analog inputs. In the case of Yamaha, even the RX-V450 (current low end model, I think) has 5.1 inputs (why not 6.1, since it is a 6.1 amplifier with 6.1 outputs ?). But for tri-amping only the RX-V650 and RX-V750 have enough channels (actually they have 7.1). The older models (RX-V640 and RX-V740) also only have 5.1 input. I realize I may need to hook in an outside 3 way crossover. The obvious choice for that would be the Behringer DCX-2496 ULTRA-DRIVE PRO One interesting thing (but I don't know if it would work) would be to use a crossover with digital input and output. I think the amplifier accepts multichannel PCM (since the DVD-video standard includes that). Anyone knows if such a crossover exists ? The Behringer DCX-2496 Ultra-Drive Pro seems to have one digital input but only analogue outputs: http://media.samedaymusic.com/media/...ed78c46ea6.pdf If the answer is receiver-dependent, I am thinking of using a Yamaha RX-V750 (not yet purchased). Any suggestions? Look for those analog inputs! A picture of the back panel may clarify the situation. http://www.yamaha.com/yec/products/RECEIVER/RX-V750.htm http://www.yamaha.com/yec/customer/manuals/RX_V750_.PDF analogue inputs (7.1) http://www.yamaha.com/yec/images/rxv750_1.gif pre-out (7.1) http://www.yamaha.com/yec/images/rxv750_4.gif About the power: all these Yamaha models have equal power for the 6 or 7 channels (7 * 100 W in the case of the RX-V750). But if you look at the specifications in the manual, it says: Power Consumption [U.S.A. and Canada models] .......400 W/500 VA So it can't send 100 W to all 7 channels simultaneously. But for tri-amping, that sould not be a problem. Assuming 100 W for each woofer, 10 W for each tweeter, that would leave 180 W for the 2 mid drivers and the amplifier itself. Of course amplifiers are far from 100% efficient, so these values will be lower in practice. -- http://www.mat.uc.pt/~rps/ ..pt is Portugal| `Whom the gods love die young'-Menander (342-292 BC) Europe | Villeneuve 50-82, Toivonen 56-86, Senna 60-94 |
|
#14
|
|||
|
|||
|
"Rui Pedro Mendes Salgueiro" wrote in message
About the power: all these Yamaha models have equal power for the 6 or 7 channels (7 * 100 W in the case of the RX-V750). But if you look at the specifications in the manual, it says: Power Consumption [U.S.A. and Canada models] .......400 W/500 VA So it can't send 100 W to all 7 channels simultaneously. Not necessarily. The name-plate power consumption of audio gear is not based on all channels running full output at the same time. This has been discussed in various audio groups in the past, but I can't remember the precise spec. I think UL bases their power spec on something like all channels at something like 10 to 15% output. Also, when amplifiers are playing music, it is virtually impossible for them to be required to produce signals with more than about 10-13 % of their equivalent maximum sine wave power at clipping. This is because music is as a rule not composed of a single pure tone. Even a single sustained bass note has substantial harmonic content, which vastly reduces its RMS power. Loudspeakers also have average impedances that generally are far greater than their rated impedance. A speaker might bottom out at rated impedance or slightly below over a few narrow bands, but when operated with music, there considerable energy at other frequencies. |
|
#15
|
|||
|
|||
|
Not necessarily. The name-plate power consumption of audio gear is
not based on all channels running full output at the same time. This has been discussed in various audio groups in the past, but I can't remember the precise spec. I think UL bases their power spec on something like all channels at something like 10 to 15% output. Also, when amplifiers are playing music, it is virtually impossible for them to be required to produce signals with more than about 10-13% of their equivalent maximum sine wave power at clipping. This is because music is as a rule not composed of a single pure tone. Even a single sustained bass note has substantial harmonic content, which vastly reduces its RMS power. Loudspeakers also have average impedances that generally are far greater than their rated impedance. A speaker might bottom out at rated impedance or slightly below over a few narrow bands, but when operated with music, there considerable energy at other frequencies. Arny, your overall explanation is correct, but I'm surprised at some of the errors in the details. First (and least-important), there is no such thing as RMS power. It can be mathematically defined, but it has no practical meaning. RMS applies only to current or voltage. When talking about the sine-wave output of an amplifier, the correct term is continuous average power. Adding harmonics to a sine wave does not decrease the waveform's average power level -- it increases it. (Obviously.) What you're talking about is crest factor. With respect to power, a sine wave has a crest factor of 3dB -- its peak power is twice its average power. Added harmonics generally increase the peak-to-average ratio. * I haven't made a systematic study of crest factor, but I've measured values of 16dB for a trumpet and piano. Most instruments have lower crest factors. A heavily compressed recording can have a very low crest factor, regardless of its harmonic content. In such cases it is theoretically possible for all the channels of an amplifier to be simultaneously driven to near-clipping _and_ full power. By definition, the "average" impedance of a driver cannot be "far higher" than its rated impedance, unless the speaker has a severe impedance dip over a narrow frequency range and the manufacturer is conservatively stating that value. In which case, we aren't talking about "average" impedance. (There have been such speakers, some of the Dayton-Wright electrostatics having impedances that range from 2 ohms to over 150 ohms being good examples. **) Intelligent speaker designers (no offense to Mr. Wright, whom I used to know) try to keep the impedance constant. The tendency is to state the lowest value, rather than the average, so that the customer won't use an amplifier that can't pump enough current. I should also point out that, although many speakers show an impedance rise near bass resonance, and this rise means that less power is delivered to the driver, the resonance offsets the loss and acoustic output remains constant. * That's generally. A square wave -- which comprises a fundamental and all its odd-order harmonics -- has a crest factor of 0dB. ** When I worked at retail, we had an FM Acoustics amp and Dayton-Wright XG electrostatics on display. The amp could not drive the upper-midrange impedance dip of the D-W's -- you could hear it "current clip" at even moderately loud levels. |
|
#16
|
|||
|
|||
|
"William Sommerwerck" wrote in message
Not necessarily. The name-plate power consumption of audio gear is not based on all channels running full output at the same time. This has been discussed in various audio groups in the past, but I can't remember the precise spec. I think UL bases their power spec on something like all channels at something like 10 to 15% output. Also, when amplifiers are playing music, it is virtually impossible for them to be required to produce signals with more than about 10-13% of their equivalent maximum sine wave power at clipping. This is because music is as a rule not composed of a single pure tone. Even a single sustained bass note has substantial harmonic content, which vastly reduces its RMS power. Loudspeakers also have average impedances that generally are far greater than their rated impedance. A speaker might bottom out at rated impedance or slightly below over a few narrow bands, but when operated with music, there considerable energy at other frequencies. Arny, your overall explanation is correct, but I'm surprised at some of the errors in the details. First (and least-important), there is no such thing as RMS power. It can be mathematically defined, but it has no practical meaning. Sure it does. The idea of RMS power is that it is an amount of power that provides heating equivalent to some amount of DC power. RMS applies only to current or voltage. When talking about the sine-wave output of an amplifier, the correct term is continuous average power. Apply a current or voltage to a more-or-less ideal resistor. The heating of that resistor will be the same as an equvalent amount of DC current or voltage. That's the basic idea of RMS. Tesla and Westinghouse needed some way to explain the practical utility of AC power to a world that was weaned on Edison's DC power. It's my understanding that we owe Tesla for RMS. Adding harmonics to a sine wave does not decrease the waveform's average power level -- it increases it. (Obviously.) Right, but the harmonics also affect the peak voltage. Peak voltages and/or currents generally set the undistorted operational limits of a power amp. Here's a practical exercise whose results you will shortly comment on, whether you meant to or not: (1) Find a segment of any real wolrd musical passage. (2) Measure its peak amplitude (3) Measure its ability to heat an ideal resistor. Compare music's ability to heat resistors (or power transformers, or heat sinks) with that of a sine wave with the same peak amplitude. The music will always be 8 dB or more weaker than the sine wave. There's at least one DAW program that facilitates this - I'm thinking of Audition/CE. Its statistics analysis facility works this all out for you each and every time you use it. What you're talking about is crest factor. Yes, that's one way to look at the problem. With respect to power, a sine wave has a crest factor of 3dB -- its peak power is twice its average power. Added harmonics generally increase the peak-to-average ratio. * I haven't made a systematic study of crest factor, but I've measured values of 16dB for a trumpet and piano. Most instruments have lower crest factors. Agreed and agreed. But there is a floor to crest factors for real-world instruments and real-world music. Its someplace around 8 dB. A heavily compressed recording can have a very low crest factor, regardless of its harmonic content. Agreed and agreed. But there is a floor to crest factors for real-world music even when heavily compressed. Its someplace around 8 dB. This same basic problem is of great interest to people who build power amps for cell tower transmitters. They end up having to overbuild the transmitters in terms of peak power handling ability, because they amplify very complex signals. There's a bunch of papers about the power content of multitones. Their final conclusions won't surprise anybody with real world experience with the details of power and signal levels inside an audio amp. In such cases it is theoretically possible for all the channels of an amplifier to be simultaneously driven to near-clipping _and_ full power. Well, theoretically, but back in the real world. There are some pathological theoretical cases that the real world seems to shield us from. One of them is *musc* that is really a single fundamental square wave, which you allude to later on. This has even a worse crest factor than a sine wave. However, there is very little if any real-world music that is this way. By definition, the "average" impedance of a driver cannot be "far higher" than its rated impedance, unless the speaker has a severe impedance dip over a narrow frequency range and the manufacturer is conservatively stating that value. In fact most drivers do have what might be called severe impedance dips. It's not the least bit unusual to find a speaker that is rated at 4 ohms, and dips down to 3 ohms at one or two frequencies. I even own a few examples, one of which is a KEF Q-15. It's peak impedance is at least 30 ohms, so its proper to say that it "...has a severe impedance dip over a narrow frequency range and the manufacturer is conservatively stating that value". In which case, we aren't talking about "average" impedance. (There have been such speakers, some of the Dayton-Wright electrostatics having impedances that range from 2 ohms to over 150 ohms being good examples. **) I did a fairly thorough job of working over a fairly large database of impedance curves before I formulated the impedance curve for my amplifier speaker simulator, as described in detail at http://www.pcavtech.com/pwramp/ .. That one peaks out at close to 60 ohms with minimums just over 3 ohms. Intelligent speaker designers (no offense to Mr. Wright, whom I used to know) try to keep the impedance constant. The tendency is to state the lowest value, rather than the average, so that the customer won't use an amplifier that can't pump enough current. In fact it's pretty easy to keep speaker impedance fairly constant. For example, just take a Q15 and shunt it with a 16 ohm resistor. Voila, the nasty-looking high peaks are gone, and minimum impedance has only dropped a little. |
|
#17
|
|||
|
|||
|
First (and least-important), there is no such thing as RMS power.
It can be mathematically defined, but it has no practical meaning. Sure it does. The idea of RMS power is that it is an amount of power that provides heating equivalent to some amount of DC power. Oh, I _got_ you Arny! Wrong, wrong, wrong, wrong, wrong. RMS AC voltage is the voltage that would produce the heating effect in a resistor as the same DC voltage. So, for example, a sine wave with 1.414 peak volts has an RMS voltage of 1.0 volts. It would heat a resistor to the same average power dissipation as 1.0 volts DC. Compare music's ability to heat resistors (or power transformers, or heat sinks) with that of a sine wave with the same peak amplitude. The music will always be 8 dB or more weaker than the sine wave. That's correct -- but it's not what you said. Well, theoretically, but back in the real world. There are some pathological theoretical cases that the real world seems to shield us from. One of them is *musc* that is really a single fundamental square wave, which you allude to later on. This has even a worse crest factor than a sine wave. However, there is very little if any real-world music that is this way. No, square waves have a lower crest factor than sine waves. But running a power amp near clipping with a square wave demands at least twice as much of the amp as does running a sine wave. Given the extreme compression of some recordings (which has been discussed here), it looks like recording engineers are increasingly producing recordings that approximate square waves. grin |
|
#18
|
|||
|
|||
|
On Thu, 1 Jul 2004 12:35:35 -0400, "Arny Krueger"
wrote: "William Sommerwerck" wrote in message By definition, the "average" impedance of a driver cannot be "far higher" than its rated impedance, unless the speaker has a severe impedance dip over a narrow frequency range and the manufacturer is conservatively stating that value. In fact most drivers do have what might be called severe impedance dips. From the standpoint of amplifier dissipation, two more issues intrude, One is that the imaginary/reactive portion of the load is *all* reflected, and must be dissipated in the amplifier. The other is that maximum internal dissipation with conventional audio amplifiers, which operate in class B for thermal purposes, occurs at lower than full output with sine waves. Somewhere around 1/3 or so, IIRC. Chris Hornbeck |
|
#19
|
|||
|
|||
|
"Chris Hornbeck" wrote in message
On Thu, 1 Jul 2004 12:35:35 -0400, "Arny Krueger" wrote: "William Sommerwerck" wrote in message By definition, the "average" impedance of a driver cannot be "far higher" than its rated impedance, unless the speaker has a severe impedance dip over a narrow frequency range and the manufacturer is conservatively stating that value. In fact most drivers do have what might be called severe impedance dips. From the standpoint of amplifier dissipation, two more issues intrude, One is that the imaginary/reactive portion of the load is *all* reflected, and must be dissipated in the amplifier. Kinda depends on how and where you look at it. It's not unusual for a speaker to have high reactance and high impedance in a given range of frequencies. In this case very little power is exchanged between the amplifier and the load. While the reactance is great, it generally isn't a troublesome load. There's not a lot of current associated with the "action". It is more unusual for a speaker to have low impedance and high reactance in a given range of frequencies, but it definately does happen. There will be quite a bit of current involved with the "action". The active devices may run hotter, but the power supply probably won't be under a lot of stress, because the net energy output is not that great. This kind of operation tends to maximize the possibility of secondary breakdown in the output transistors. For that reason, it will also tend to activate any protective devices, if the output stage lacks the needed ability to handle this kind of load. When I was designing my speaker simulator, I studied this mode of operation more than any other, and tried to come up with an electrical network that was a reasonable worst case simulation of a speaker that was agressively designed on this count. The other is that maximum internal dissipation with conventional audio amplifiers, which operate in class B for thermal purposes, occurs at lower than full output with sine waves. Somewhere around 1/3 or so, IIRC. Agreed. |
|
#20
|
|||
|
|||
|
The other is that maximum internal dissipation with conventional
audio amplifiers, which operate in class B for thermal purposes, occurs at lower than full output with sine waves. Somewhere around 1/3 or so, IIRC. The FTC standards require pre-conditioning at 1/3 rated power. This is about the worst-possible operating condition, and as it's about 5dB below full output, it bears little relationship to real-world operating conditions. |
|
#21
|
|||
|
|||
|
RLS wrote:
Is it possible to use a modern 6.1 or 7.1 home-cinema receiver for tri-amping a classical stereo setup? Depends, if it has direct power amp inputs: in theory yes. (I have never owned such a receiver, so I am just speculating) I realize I may need to hook in an outside 3 way crossover. If the answer is receiver-dependent, I am thinking of using a Yamaha RX-V750 (not yet purchased). Any suggestions? Look for a multichannel poweramp, normally I use a NAD 906 for my small monitors, but it is currently off sick: the treble channel pair suddenly ran very hot. And yes, you will need a cross-over. DIY or Behringer comes to mind, there are others, dunno if NAD still makes 6 channel amps, Rotel used to have something similar, go Google. Kind regards Peter Larsen -- ******************************************* * My site is at: http://www.muyiovatki.dk * ******************************************* |
|
#22
|
|||
|
|||
|
Arny Krueger wrote:
Look for those analog inputs! A picture of the back panel may clarify the situation. And DO compare the power specs with the electrical specs, I have seen somebody incorrectly choose a surround receiver for use as a multichannel poweramp. They thought it had 6 X 130 watts, it has 6 amps that can deliver 130 watts with two channels driven and a max power consumption of 550 watts, i.e. no more than some 65 watts pr channel all channels driven. Such a limitation may matter less for running a multiway speaker system and less even if a separate subwoofer amp is deployed. Kind regards Peter Larsen -- ******************************************* * My site is at: http://www.muyiovatki.dk * ******************************************* |
|
#23
|
|||
|
|||
|
And DO compare the power specs with the electrical specs, I have seen
somebody incorrectly choose a surround receiver for use as a multichannel poweramp. They thought it had 6 X 130 watts, it has 6 amps that can deliver 130 watts with two channels driven and a max power consumption of 550 watts, i.e. no more than some 65 watts pr channel all channels driven. Good point. However, surround sound simply tends to sound louder than stereo. You can "get away" with 3dB to 6dB less power per cannel. Of course, if you still play stereo recordings with no multi-channel enhancement, that won't do you any good. |
|
#24
|
|||
|
|||
|
William Sommerwerck wrote:
And DO compare the power specs with the electrical specs, I have seen somebody incorrectly choose a surround receiver for use as a multichannel poweramp. They thought it had 6 X 130 watts, it has 6 amps that can deliver 130 watts with two channels driven and a max power consumption of 550 watts, i.e. no more than some 65 watts pr channel all channels driven. Good point. However, surround sound simply tends to sound louder than stereo. You can "get away" with 3dB to 6dB less power per cannel. Of course, if you still play stereo recordings with no multi-channel enhancement, that won't do you any good. It is in fact a wise design for surround all things considered, which is why I omit the make and model in this context. What is not wise is to want to use that receiver to amplify announcers vox on a grassy meadow using 6 ground located rock look-alike "blending in" loudspeakers, in the context a visually good idea, with an 89 dB sensitivity .... a Crown XLS 402 and 6 times something with 99 dB sensitivy makes more sense for that purpose I reckon ... Kind regards Peter Larsen -- ******************************************* * My site is at: http://www.muyiovatki.dk * ******************************************* |
| Reply |
| Thread Tools | |
| Display Modes | |
|
|
Similar Threads
|
||||
| Thread | Forum | |||
| FS: Sony STR-G3 Home Theater Receiver | Marketplace | |||
| Surround audio problems with Pioneer VSX-36TX receiver | Tech | |||
| Yamaha DSP-A2070 Surround Sound Receiver | Marketplace | |||
| YAMAHA RX-830 Surround Receiver - below Bluebook | Marketplace | |||
| What's a good bang for the buck surround receiver? | Pro Audio | |||
Linear Mode
