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Front firing or downfiring Tempest?

Discussion in 'Archived Threads 2001-2004' started by Ryan T, Jan 7, 2002.

  1. Ryan T

    Ryan T Second Unit

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    I have made my decision on a sub box and subwoofer but I have one more question concerning the driver mounting. I'm going to build the 230L seald box that is provided on the adire website here http://www.adireaudio.com/Tech%20Pap...mpest_apps.htm
    My only problem with it is that the design has you mount the driver on the bottom of the box. It is not a real big problem but I would really like to have it front firing. So i'm wondering if I could change the design and mount the driver on the side. If I do this will it hurt the performance or anything? also why does adire use the downfiring designs on so many of there reference designs?
    Ryan
     
  2. Patrick Sun

    Patrick Sun Studio Mogul

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    Low frequency is mainly "omni-directional" so it doesn't really matter if you down-fire or front-fire the sub driver. Some people prefer to keep the driver out of the way of curious hands (kids) via down-firing the driver. Others like the looks of front-firing subs.
     
  3. Pete Mazz

    Pete Mazz Supporting Actor

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    Not having to buy or make a grill is another reason to downfire. You can also disguise the sub easier if you need to.

    Pete
     
  4. Ryan T

    Ryan T Second Unit

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    I think I will make it front firing since I don't have to worry about kids because i'm the youngest one In this house[​IMG]. I'm a little worried that my sub will be crossed over two high. My receiver is a Sherwood surround sound receiver and it does not give the frequency of the subwoofer crossover. I just have the option to set the speakers to small or large, Large cuts the sub out and small gives a signal to the sub. Is there any way to find out the subwoofer crossover frequency? thanks for all the help.
    Ryan
     
  5. Brian Bunge

    Brian Bunge Producer

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    Ryan,

    You're receiver's subwoofer crossover point should be listed in the specs section of the owner's manual. I have a Sherwood Newcastle receiver and it is fixed at 100Hz.

    Brian
     
  6. Scott Simonian

    Scott Simonian Screenwriter

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    I agree with Brian, I dont have or know much about Sherwood receivers but it is the "norm" to have a 100hz crossover. I dont think it should be but that is how it is most of the time. Just hope its not 120hz or 200hz(!). Hey, you may be lucky and find it is a 80hz x-over. [​IMG]
     
  7. Ryan T

    Ryan T Second Unit

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    I've looked through the manual 3 times and there is nothing about the subwoofer crossover. it just says "Subwoofer pre-out, connect a subwoofer to emphasize the deep bass sound." and the specifications section in the back of the manual does not say anything about the Sub crossover! I've E-mail the company twice and both times I got no response so I just gave up[​IMG]. The model number is RD-7103 if that helps any. I've heard that a amplifier cannot output more power than it consumes is this true? anyway this is supposed to do 100 watts X 5 into 6 ohms but it only consumes 200 watts whats the deal? It is a cheapo receiver it only cost me $160 new and I really want to upgrade soon, maybe I will get a onkyo or outlaw or somthing.
    Ryan
     
  8. Travis G

    Travis G Stunt Coordinator

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    Ryan,

    No an amplifier can not produce more power than it consumes. Class AB amplifiers are the most common in hi-fi and the ammound of power they can produce is usually somewhere between 50% and 75% of the power they consume. The rest gets turned into heat. Is it 100 watts * 5 can mean alot of things though sometimes manufacturers list peak output and sometimes list peak to peak (peak output * 2). Sometimes they list continuous wich is perfered. Some will list "music power" which is absolutely meaningless because it depends largely on the program material chosen.

    A friend of mine recently bought a small pair speakers with a "subwoofer" that matched his Playstation 2. The system claimed to be 300 watts PMPO (Peak Music Power Output). A better rating for this system would have read 300 watts WHFO (When Hell Freezes Over). Upon closer examination I discovered that this system put off 26 Watts continuous.

    Travis
     
  9. SimonInd

    SimonInd Auditioning

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    I've just (nearly) completed the 230L Sealed Tempest and it sounds excellent. Mine is downfiring with 'feet' made out of the 4" circles that were cut out of the bracing pieces. The box is glued up but not yet painted/veneered so I can't really call it finished! I'm sure it would be fine in a front firing alignment but downfiring does have the advantage of protecting the driver a bit more.

    I'm using a 500W plate-amp to power the little fella and rather than my amp's crossover ( standard 80Hz THX affair ) I'm taking the Left and Right pre-amp outs and using the crossover built in to the plate-amp. This is currently set quite high ( about 160Hz ) given that it is operating with Epos ES22 floorstanding speakers, however this does seem to provide the best 'integration' for music. SPL meter is in the mail so I'll measure it and set it up properly once I have that.

    One thing I wasn't sure of was whether front firing subs would be more sensitive to room-placement? Mine is affected massively depending on where it is in my 16'x12'x8' room so beware of this.

    Cheers

    Simon
     
  10. Ryan T

    Ryan T Second Unit

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    I just thought of how to find the crossover point. I have my computer hooked up to my HT and so I just downloaded a tone generator and then I unhooked my sub. I can tell the sound starts droping of around 80 to 100HZ so I think it is crossed over in that area. If there is any other way to test it please let me know, thanks.

    Ryan
     
  11. Brian Bunge

    Brian Bunge Producer

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    Ryan,

    You could do the exact same thing you describe above but this time actually measure the SPL with the Radio Shack SPL meter. The point where the SPL is 3dB lower is the crossover point. So say the output is 80dB at 110, 105, 100Hz and slowly starts to drop as you set the frequency lower. The frequency at which the output is 77dB will be the crossover point.

    Brian
     
  12. Ryan T

    Ryan T Second Unit

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    So if my receiver consumes only 200 watts I should not hurt my paradigm titans that are rated at 60 watts max. I guess I should worrie more about the receiver clipping than over powering the titans. as soon as I get a Radio Shack SPL meter I will find the crossover point. Thanks for the help.

    Ryan
     
  13. NathanP

    NathanP Supporting Actor

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    Dude,

    When you get that Shiva done, your parents are going to kick your ass..
     
  14. Ryan T

    Ryan T Second Unit

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    Tempest not shiva. and yes they most likely will [​IMG].
     
  15. Travis G

    Travis G Stunt Coordinator

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    Ryan,

    Are you sure that your reciver only consumes 200 watts of power? I it up on the net and this is what it said:

    • 100 Watts x 2 @ 6 Ohms, 40 Hz-20 kHz with no more than 0.9% THD

    • 100 Watts x 5 @ 6 ohms, 1 kHz 0.9% THD

    • Surround modes

    • Totally Discrete Amplifiers (TDAS) for all channels

    The first spec tells us that with two channels driven into 6 ohm loads the amplifier will produce less than 0.9% harmonic distortion between 40 Hz and 20 kHz.

    Is this where you saw the 200 watts?
     
  16. Ryan T

    Ryan T Second Unit

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    The manual says it only consumes 200 watts and the back of the receiver it says
    AC input
    120V~60hz
    200Watts
    I don't doubt that this could be wrong because there has been so many contradictions with what the manual and internet say and what is really on the back of the receiver. Here is one the manual says that there are "PRE OUT(Front, Center, Rear, Subwoofer)" and guess what no front, center or rear channel pre out on the back of the receiver just a subwoofer pre out. And in my Sound & Vision buyers guide it says that the Sherwood RD-7103 has "100 Wx5 RMS into 6 ohms from 40 Hz-20 kHz with 0.9% THD". And if you look here http://www.sherwoodusa.com/corp/ha_pr1.htm
    scroll down the page a bit to the RD-7103 it says...
    "The new RD-7103 receiver is rated at 100 watts per channel in stereo from 40 Hz to 20 kHz into 8 ohms with no more than 0.05% THD and 100 watts per channel x 5 in the surround mode. It continues the 6-Channel Direct input and uses the new YSS-912 digital decoder for DTS(tm), Dolby Digital, Dolby Pro Logic and to provide 3 DSP modes. The RD-7103 has 4 digital inputs, (2 Optical Toslink and 2 Coaxial), 3 AV inputs and 4 audio inputs. The RD-7103 also has an advanced digital tuner with 4-gang front end and 30 station presets, 6 preamp outputs and includes a universal, preprogrammed remote control to operate up to 8 components. Suggested retail price for the RD-7103 is $349.95 and will be available in May."
    My receiver only has 3 digital inputs 2 coaxial and 1 optical, it has 0.9%THD into 6 ohms not 0.05& into 8 ohms and there are no preamp outputs other than subwoofer pre out. I'm very frustrated with the whole thing and the fact that Sherwood chooses to ignore all my e-mails does not help
    [​IMG].
    Ryan
     
  17. Brian Bunge

    Brian Bunge Producer

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    Ryan,

    Have you tried contacting Jeff Hipps of Sherwood USA? He's a HTF member and usually is very helpful with questions concerning the Newcastle line. I imagine he could also provide you with feedback on your receiver as well.

    Brian
     
  18. Ryan T

    Ryan T Second Unit

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    I just sent a e-mail to Jeff so maybe I will finally get some answers [​IMG]. Thanks for the suggestion Brian. By the way I went ahead and called Circuit City and asked them about the watts here is what they said, "the watts your receiver consume has nothing to do with the watts it outputs" Hey it was worth a good laugh.
    Ryan
     
  19. Travis G

    Travis G Stunt Coordinator

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    LOL that sounds like something you would here from a worker at Circut City.

    Come to think of it though it doesn't say that it uses 200 watts at full power does it. I'm not sure what the 200 watts represents but an amplifier does not need the same amount of power at low levels that it needs at high levels.
     
  20. Ryan T

    Ryan T Second Unit

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    I've been looking in my manual for power output and here is what it says...
    "Surround sound mode, only channel driven
    Front power output, 6 ohms, 1 kHz, THD 0.7 _____125 W/125 W
    Center power output, 6 ohms, 1kHz, THD 0.7 _____125 W
    Rear power output, 6 ohms, 1 kHz, THD 0.7 ______125 W/125 W"
    I think the ONLY CHANNEL DRIVEN part means that it cannot output 125 W to all of the channels at the same time. So I figure if it only can output 125 W total it must be giving around 25 watts to each channel at 8 Ohms [​IMG]. I guess it could be 200 Watts minimum consumption but it does not make much sense to list that on the back of the receiver.
    Ryan
     

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