Shakers - Simple/Cheap Hookup - Visual Guide - Page 54 - AVS Forum
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post #1591 of 2538 Old 08-25-2008, 09:07 AM
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Thanks. I think my best bet would be to swap out the 10 gauge I put in there and run my leftover 16 in its place. I guess I have to go back and drill a couple more holes

My build thread:
The Maple Street Theater
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post #1592 of 2538 Old 08-25-2008, 04:52 PM
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I guess I have to go back and drill a couple more holes

Better now than later......

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post #1593 of 2538 Old 08-26-2008, 04:09 AM
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What typical sound effects were omitted/attenuated with the use of the 50Hz FMOD?

Eclectic Electronics: A blog containing technology news, information about home theater, digital photography and more.
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post #1594 of 2538 Old 08-26-2008, 05:31 AM
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Originally Posted by blued888 View Post

What typical sound effects were omitted/attenuated with the use of the 50Hz FMOD?

The sounds with frequencies above 50Hz.
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post #1595 of 2538 Old 08-26-2008, 08:45 AM
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If I am looking to buy a used receiver what specs should I look for?
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post #1596 of 2538 Old 08-27-2008, 03:56 AM
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Originally Posted by J. L. View Post

The sounds with frequencies above 50Hz.

I meant... Hmmm... What are some examples of sounds that fall in the 50Hz to 80Hz region? Like small drum beats, deep voices?

Did you choose to use a 50Hz FMOD? Thanks!

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post #1597 of 2538 Old 08-27-2008, 06:59 AM
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Quote:
Originally Posted by blued888 View Post

I meant... Hmmm... What are some examples of sounds that fall in the 50Hz to 80Hz region? Like small drum beats, deep voices?

I did put a
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Did you choose to use a 50Hz FMOD? Thanks!

No, I did not. (My RX crossover is set to 80Hz) Those same deep voices and sounds between 50 and 80Hz are being sent to my subwoofers and the shakers.

My subwoofers have a bit more effect on my theater experience than those in some home theaters. In fact, they vibrate and rumble the room even without the bass-shakers. I have two large-excursion Ascendent Audio 18" drivers, each displacing 6.5 Liters of air, each in a 12.5 cubic foot enclosure, each fed with about 700 watts of power. The frequency response is pretty decent even down to the low teens and below. (I use a BFD as a parametric equalizer for just the subwoofer amplifier channel)

With 13 Liters of displacement, and roughly 1400 watts powering the subwoofers, the aura shakers only fill in the total experience.

With the same 50 to 80Hz sounds coming from the front of the room, I cannot really detect them as a distraction from the shakers.

Joe L.
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post #1598 of 2538 Old 09-08-2008, 03:25 AM
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Hello all-
I was planning on using four pro shakers on my couch in my living room with my Emotiva BPA-1 (75w x2 at 4ohm / 150x x1 at 8ohm). I am sending the signal split from my Pioneer Elite receiver sub out to two Jamo 650subs (one front and one rear) and then pass through the sub to the BPA-1 then mono out to the shakers wired in ?. What is the best way to wire these up- parallel vs series parallel? Does anyone see a problem with my plan plan?

Pioneer Elite - splitter - Jamo Subs (pass through in stereo) - Emo BPA-1 - 4 Aura Pro Shakers

Thank you for the help!
Nik
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post #1599 of 2538 Old 09-25-2008, 02:46 PM
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Okay, I'm in.

I ordered:
- 1x Sony STR-DG500 ($75 shipped off eBay)
- 4x 50watts shakers ($160 shipped off Part Express)

I am planning to mount all 4 on my theater sofa.

The Sony is rated at 660 watts but is really a 220 watts amp with 100 watts/ch in stereo mode (8 ohms @ 20hz - 20000hz).
Do you guys think the Sony will run the 4 shakers at full load without overloading?
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post #1600 of 2538 Old 09-25-2008, 08:24 PM
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Quote:
Originally Posted by spectrumbx View Post

Okay, I'm in.

I ordered:
- 1x Sony STR-DG500 ($75 shipped off eBay)
- 4x 50watts shakers ($160 shipped off Part Express)

I am planning to mount all 4 on my theater sofa.

The Sony is rated at 660 watts but is really a 220 watts amp with 100 watts/ch in stereo mode (8 ohms @ 20hz - 20000hz).
Do you guys think the Sony will run the 4 shakers at full load without overloading?

Since the shakers will probably take about 10 to 15 watts each before bottoming out at certain frequencies, I'd say you will never use that amplifier at anywhere near its normal output... therefore I don't think it will ever overheat with two 8 ohm loads. (two shakers in series on each channel)

If you did run the amp at full output, the shakers will probably be near or at their thermal limits. Be careful with the volume control... it will be easy to overpower your set of shakers if you turn it up too much.

Joe L.
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post #1601 of 2538 Old 09-26-2008, 08:16 AM
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Quote:
Originally Posted by J. L. View Post

Since the shakers will probably take about 10 to 15 watts each before bottoming out at certain frequencies, I'd say you will never use that amplifier at anywhere near its normal output... therefore I don't think it will ever overheat with two 8 ohm loads. (two shakers in series on each channel)

If you did run the amp at full output, the shakers will probably be near or at their thermal limits. Be careful with the volume control... it will be easy to overpower your set of shakers if you turn it up too much.

Joe L.

Ah cool... thanks.
I have not checked yet, but I guess I should set a volume cap on the Sony.

Now, this brings up another issue.
How do I synch the volume level from the main receiver to the Sony to keep things at the same level?

Also, I will be doing coaxial SPDIF out from my HTPC to the Sony, which means that the full sound range will be sent to the shakers.
I also understand that the shakers have their own crossover hard set to 40-80hz.
The Sony will be set to stereo and no subwoofer (full range output to the stereo).
Is my setup optimal or should I output only the sub out from the main receiver to the Sony? Why?

Thanks.
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post #1602 of 2538 Old 09-26-2008, 12:21 PM
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hello everyone

This is a great thread btw, but there is SO much information! I'm sure this has been asked before, but I havn't been able to find an answer on my own:

I have a three person couch, and was thinking 2 or 3 of the aura bass shakers.

What is the cheapest route to go for powering them? If a stereo receiver will work, I'm sure i can find a used one for a good price, but my question is, what specific specs should I look for to make sure the receiver will do a good job -(and are there any recommended old school receivers that would work?

Also, with two i see that you can go out from left and right chan, what do you do with 3? Or would it make more sense to just get 4?

Thanks in advance!
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post #1603 of 2538 Old 09-26-2008, 01:01 PM
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Quote:
Originally Posted by asalerno View Post

hello everyone

This is a great thread btw, but there is SO much information! I'm sure this has been asked before, but I havn't been able to find an answer on my own:

I have a three person couch, and was thinking 2 or 3 of the aura bass shakers.

What is the cheapest route to go for powering them? If a stereo receiver will work, I'm sure i can find a used one for a good price, but my question is, what specific specs should I look for to make sure the receiver will do a good job -(and are there any recommended old school receivers that would work?

Also, with two i see that you can go out from left and right chan, what do you do with 3? Or would it make more sense to just get 4?

Thanks in advance!

Buying a cheap used receiver or boombox (those that use speaker wires) will get you the most value versus buying a subwoofer amp.
Note that a lot of receivers over-rate their wattage.

My Sony STR-DG500, for instance, is rated at 660 watts but is really a 200 watts amp.
The true amp wattage is what really matters here.

As J. L. posted, the 50 watts shakers would need 10-15 watts.
This means that any 100 watts amp should be able to power 4 shakers with ease.

You should get 4 shakers and drive them in pair @ 8 ohms off each of the right and left channels.
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post #1604 of 2538 Old 09-26-2008, 01:06 PM
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Quote:
Originally Posted by spectrumbx View Post

Buying a cheap used receiver or boombox (those that use speaker wires) will get you the most value versus buying a subwoofer amp.
Note that a lot of receivers over-rate their wattage.

My Sony STR-DG500, for instance, is rated at 660 watts but is really a 200 watts amp.
The true amp wattage is what really matters here.

As J. L. posted, the 50 watts shakers would need 10-15 watts.
This means that any 100 watts amp should be able to power 4 shakers with ease.

You should get 4 shakers and drive them in pair @ 8 ohms off each of the right and left channels.

thanks for the quick reply! so ill just look for a stereo amp that has a true 100 watts and ill be good? is there a way to check a receiver's true wattage?

Also - if i went with an AV receiver, could i get three and use the center chan?
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post #1605 of 2538 Old 09-26-2008, 01:10 PM
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Quote:
Originally Posted by asalerno View Post

hello everyone

This is a great thread btw, but there is SO much information! I'm sure this has been asked before, but I havn't been able to find an answer on my own:

I have a three person couch, and was thinking 2 or 3 of the aura bass shakers.

What is the cheapest route to go for powering them? If a stereo receiver will work, I'm sure i can find a used one for a good price, but my question is, what specific specs should I look for to make sure the receiver will do a good job -(and are there any recommended old school receivers that would work?

Also, with two i see that you can go out from left and right chan, what do you do with 3? Or would it make more sense to just get 4?

Thanks in advance!

You can put three in series for a 12 ohm load and power them from a single channel amplifier... if the amplifier is rated at 100 watts into 8 ohms, it will provide about 75 watts into 12. Divided between three shakers, an almost perfect match...

or

you can put two shakers in series on one channel of a stereo amp, and one on the other channel, and then adjust the left/right balance control to make the single shaker shake the same amount as the other two. (you will need to turn the channel with one down, and the channel with the two up)

No other wiring will make them all shake evenly except all in parallel, but that would end up as a 1.3 ohm load, way too low for most amplifiers, and certainly way too low for the average budget/used stereo amp.
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post #1606 of 2538 Old 09-26-2008, 01:48 PM
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Quote:
Originally Posted by asalerno View Post

thanks for the quick reply! so ill just look for a stereo amp that has a true 100 watts and ill be good? is there a way to check a receiver's true wattage?

Also - if i went with an AV receiver, could i get three and use the center chan?

Can't use center channel unless the internal bass management of the receiver can be disabled so it feeds the full frequency range to all the channels. Actually, that goes for left and right channel too. Almost anything old and made for multi-channel home theater use will be limited in allowing you to disable the bass management.

There are four easy ways to check "true wattage"


1. Measure it. (measure the RMS voltage with a steady tone, multiply by itself, divide by the load resistance.)
2. Read reviews where it is been measured by someone other than the manufacturer. (They are more likely to give a true value)
3. Read the back of the receiver... Most will be between 70 and 85% efficient. If it says it draws 100 watts from the AC wall outlet, the most it can output to the speakers (shakers) is 70 to 85 watts. A 200 watt output receiver should say it draws 250 watts or more from the AC wall outlet.
If the receiver has an amperage listed instead of watts, just multiply by 120 (volts) to get the equivalent wattage.

Here is an example... My personal receiver says it draws 6.6 Amps input from the AC line at 120 volts. It therefore draws 792 watts from the wall outlet. Assuming 80% efficiency, I can get, at most, 633 watts output. (regardless of the number of channels, can't get more power out than you put in, the difference being wasted as heat.)

Now, my receiver manufacturer rates my unit for two channels driven at once, not all seven, so they have it conservatively rated at 110 watts per channel, with two channels driven, into 8 ohms. Obviously, with all 7 channels driven, I can get only 90 watts per channel if they keep to the 6.6 amp listing on the rear panel, so odds are it draws a bit more than 6.6 amps probably closer to 7 amps with all channels driven. Now, all this said, my receiver is made by Harmon Kardon, and they are one of the few to honestly list the power output. With 5 channels driven into 8 ohms, it was measured at over 140 watts per channel by one reviewer.

4. The final way to determine if the wattage rating is somewhat honest. Weight. Unless the receiver is a very new design with a switched digital power supply it will have a large power transformer. That MUST be fairly heavy for any amount of power, you cannot cheat physics, even if the marketing staff would like it to be able. My HK receiver weighs nearly 55 pounds. Yup... need a very sturdy shelf to hold it...

Expect a "true" 100 watt receiver to weigh 15-20 lbs or more.

Joe L.
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post #1607 of 2538 Old 09-26-2008, 07:09 PM
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IMHO, if you want bang for buck try and find a receiver that has 2 sets of main speaker outputs. Most will be labeled speakers "A" and "B". That way you can runs 2 shakers on each channel for a total of 8 with an 8 ohm load and not have to worry about overheating the amp and shutting it down.

Just split the output from the LFE channel of your main AVR and run it into both the left and right inputs on your shaker receiver. I used the "tape" input on mine.

I'm using 4 shakers right now on channel A of my old JVC receiver (2 on the right channel, 2 on the left) with the option of adding 4 more in the future if I choose to.
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post #1608 of 2538 Old 09-27-2008, 12:53 AM
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Quote:
Originally Posted by Jailer View Post

IMHO, if you want bang for buck try and find a receiver that has 2 sets of main speaker outputs. Most will be labeled speakers "A" and "B". That way you can runs 2 shakers on each channel for a total of 8 with an 8 ohm load and not have to worry about overheating the amp and shutting it down.

Just split the output from the LFE channel of your main AVR and run it into both the left and right inputs on your shaker receiver. I used the "tape" input on mine.

I'm using 4 shakers right now on channel A of my old JVC receiver (2 on the right channel, 2 on the left) with the option of adding 4 more in the future if I choose to.


No, it don't work that way. Receivers with a set of speaker A & B output like you mention for a pair of stereo channels, are only just sharing the exact same amplifier power output via a selectable switch. Just because it has a A & B output, does not in any way mean it has two more additional amplifiers for the "B" outputs. It don't, it is only sharing power with the "A" outputs. And if you do what you mention, it still will be the same thing and the same load on the as running a total of 8 shakers (4 per channel) on only two L&R ouputs of the receiver.
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post #1609 of 2538 Old 09-27-2008, 09:37 AM
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Quote:
Originally Posted by Jailer View Post

IMHO, if you want bang for buck try and find a receiver that has 2 sets of main speaker outputs. Most will be labeled speakers "A" and "B". That way you can runs 2 shakers on each channel for a total of 8 with an 8 ohm load and not have to worry about overheating the amp and shutting it down.

Just split the output from the LFE channel of your main AVR and run it into both the left and right inputs on your shaker receiver. I used the "tape" input on mine.

I'm using 4 shakers right now on channel A of my old JVC receiver (2 on the right channel, 2 on the left) with the option of adding 4 more in the future if I choose to.

If running at 8 ohms is your concern, then a receiver like mine is best.
I can run 12 shakers @ 8 ohms on its 6 channels set to full range and enabling multi channel stereo.

However, you are not restricted to an 8 ohm load and you will have other options depending on the receiver.

If your receiver only supports 2 ch stereo but also supports A+B (not just A/B), then, yes, you can effectively have 4 channels driven at 8 ohms with 8 shakers.
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post #1610 of 2538 Old 09-27-2008, 02:20 PM
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Quote:
Originally Posted by Johnla View Post

No, it don't work that way. Receivers with a set of speaker A & B output like you mention for a pair of stereo channels, are only just sharing the exact same amplifier power output via a selectable switch. Just because it has a A & B output, does not in any way mean it has two more additional amplifiers for the "B" outputs. It don't, it is only sharing power with the "A" outputs. And if you do what you mention, it still will be the same thing and the same load on the as running a total of 8 shakers (4 per channel) on only two L&R ouputs of the receiver.

But each channel of the A and B will handle a pair of shakers. 8 Ohms per channel, 2 channels per speaker output. 4 total outputs with 2 shakers on each with an 8 Ohm load is 8 shakers without having to worry about overloading the receiver with a 4 ohm load.

If what you gave as an example was true, the receiver would see a 4 ohm load if both sets of speakers A and B were selected and that's just not the case. In your example of 8 shakers (4 on each of 2 channels) you can not come up with a 8 ohm load and keep the receiver functioning.

With my example you get 8 shakers all having the same load on the receivers amp and shaking the same amount.
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post #1611 of 2538 Old 09-27-2008, 08:39 PM
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Quote:
Originally Posted by Jailer View Post

But each channel of the A and B will handle a pair of shakers. 8 Ohms per channel, 2 channels per speaker output. 4 total outputs with 2 shakers on each with an 8 Ohm load is 8 shakers without having to worry about overloading the receiver with a 4 ohm load.

If what you gave as an example was true, the receiver would see a 4 ohm load if both sets of speakers A and B were selected and that's just not the case. In your example of 8 shakers (4 on each of 2 channels) you can not come up with a 8 ohm load and keep the receiver functioning.

With my example you get 8 shakers all having the same load on the receivers amp and shaking the same amount.

No, you are wrong. If it only has a stereo L&R output, then it also ONLY has two channels of amplification for stereo L&R output. The fact that something may have A & B (or A+B) speaker switch, does not in any way double the amount of amplifiers it has or split the load on it. All it really does is share outputs, and the load will be the same as if you hooked up 4 shakers/speakers to each L&R output.
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post #1612 of 2538 Old 09-27-2008, 10:51 PM
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Quote:
Originally Posted by Johnla View Post

No, you are wrong. If it only has a stereo L&R output, then it also ONLY has two channels of amplification for stereo L&R output. The fact that something may have A & B (or A+B) speaker switch, does not in any way double the amount of amplifiers it has or split the load on it. All it really does is share outputs, and the load will be the same as if you hooked up 4 shakers/speakers to each L&R output.

I believe that in the A+B case, power is transfered from the rear channel to the B channel.
This is effectively 4 channel stereo.
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post #1613 of 2538 Old 09-27-2008, 11:21 PM
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Quote:
Originally Posted by spectrumbx View Post

I believe that in the A+B case, power is transfered from the rear channel to the B channel.
This is effectively 4 channel stereo.

If it is only a two channel receiver, that is not even at all possible, as there are no rear channels to transfer the power from. There are even many multi channel receivers that will not do that, unless there is a specific way for setting it up for using a otherwise unused set of rear channel outputs, such as a bi-amp setting on some AVR's. And most of the older or low cost AVR's that many people are thinking of using for this, do not have that feature. I used to have a older two channel Kenwood flagship receiver that weighed about 50lbs and was rated for 165wpc, and that actually tested in few magazine reviews back in that era to put out closer to 190wpc. And it had a A, B, C plus a A+B speaker selection switch, and there was no extra amps and no extra power available for when you operated it at A+B setting, it only shared the same power among them. And in fact, you could even see the extra draw showing up on the built in power meters it had, from the increased load of running two sets of speaker at one time.

Now if a multi channel receiver has a some sort of a stereo party mode setting, in order to run it as stereo L&R only output to all of the 5-7 speakers in a normal surround setup. Then other than not being called a A+B speaker switch setting, it probably would work somewhat like you say, and also probably work for the shakers with that type of setting as well, that is, if it is a available option on the AVR that's being used.
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post #1614 of 2538 Old 10-03-2008, 11:05 PM
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Ok, I have everything setup, but now I have a problem.

I am doing :
- digital optical out to my main receiver, which drives the speakers
- digital coaxial out to a secondary receiver, which powers the shakers

My problem is that the shakers are getting the full range of sound, and at times shakes at unsolicited moments.

Are the shakers supposed to have a fix response range of 20-80hz?
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post #1615 of 2538 Old 10-06-2008, 09:29 AM
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spectrumbx, you should be connecting the analog RCA cable from the subwoofer pre-amp output of the receiver, not the digital coax output. Completely different signals (and analog vs digital).

As for limiting the output (which may be an issue even connected to the right output).. if you don't have a sub, you can set the crossover in your receiver to whatever level you want to limit the shaking even further (e.g. 50Hz). If you already have a sub connected to the sub output, then use an RCA Y-cable. You can then get an inline FMOD low-pass filter if you want additional filtering beyond the built-in crossover of the receiver.

Let me know if something above doesn't make sense..
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post #1616 of 2538 Old 10-06-2008, 01:56 PM
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Quote:
Originally Posted by miltimj View Post

spectrumbx, you should be connecting the analog RCA cable from the subwoofer pre-amp output of the receiver, not the digital coax output. Completely different signals (and analog vs digital).

As for limiting the output (which may be an issue even connected to the right output).. if you don't have a sub, you can set the crossover in your receiver to whatever level you want to limit the shaking even further (e.g. 50Hz). If you already have a sub connected to the sub output, then use an RCA Y-cable. You can then get an inline FMOD low-pass filter if you want additional filtering beyond the built-in crossover of the receiver.

Let me know if something above doesn't make sense..

My setup is as follow:

HTPC -> digital optical -> primary receiver -> speakers & subs
HTPC -> digital coaxial -> secondary reciever -> bass shakers

So, I have two receivers fully processing the digital sound out of my HTPC.

The full processing of the sound by the secondary receiver is where the problem lies.
It works, but the shakers are also outputting high/mid ranges.

I understand that I could connect the secondary receiver to the sub out of the primary one, but it is simpler for me to have my current configuration.

Anyway, it is looking like I am going to have to suck it up and do it the analog way.
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post #1617 of 2538 Old 10-08-2008, 01:46 AM
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Quote:
Originally Posted by spectrumbx View Post


I understand that I could connect the secondary receiver to the sub out of the primary one, but it is simpler for me to have my current configuration..


It is not a matter of "could", or which way is "simpler" for you to hook up, it is a matter which way works for what you need it to do and which way don't.

What you are doing, by feeding the secondary receiver a full range digital signal will not work the way you need it to. To get the LFE signals that you need for the shakers into the secondary receiver, you must use the analog subwoofer output of the primary receiver to feed the analog inputs of the scecondary receiver.
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post #1618 of 2538 Old 10-08-2008, 09:51 AM
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Quote:
Originally Posted by spectrumbx View Post

My setup is as follow:

HTPC -> digital optical -> primary receiver -> speakers & subs
HTPC -> digital coaxial -> secondary reciever -> bass shakers

I understand that I could connect the secondary receiver to the sub out of the primary one, but it is simpler for me to have my current configuration.

You'll need to connect the secondary receiver either inline (parrallel) with your current sub through LFE input or connect your secondary receiver to the line level out of your sub, if it has one. I havent seen a powered sub in some time that didnt have a line level out. Any other way is walking around the mountain to pee next door.

You could also do this:
HTPC -> digital optical -> primary receiver -> speakers & subs
HTPC -> digital coaxial -> secondary reciever LFE OUT-> Tertiary receiver -> bass shakers

but that would be VERY bassackwards. At that point you're simply using the secondary receiver to break out the LFE channel and you're using the tertiary receiver to provide the power to the shakers. It would work but why do it?

Quote:
Originally Posted by vasyachkin
Even i, the genius, only vaguely understand what i am saying here.
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post #1619 of 2538 Old 10-08-2008, 11:15 AM
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Ok, I've been reading this thread for the better part of a week and there seems to be a handful of questions being asked over and over. I have recently hooked up a couple sets of shakers in my theater and will post some tools, info and things I've noticed.


Pro vs non-Pros

It seems from other's experiences and my phone calls to aura that there is no difference between the pro and standard bass shaker aside from the housing. The pros have fins to dissipate heat, the standards do not. These units were originally designed for car audio. This means operating in tiny spaces surrounded by lots of insulation. It also means that its probably going to be driven by some audio thats bass heavy which results in them being active more often than not. This is also why aura recommends them to be set at 100hz low pass. In a car there wont be any Darth Vader voices or door slams that break the realism, just music. I realize that people do watch movies in their cars and other things that result in situations other than described but these weren't intended for those exceptions.

In home audio, in situations where you have more ventilation, you could easily drive the standards with the same power as the pros. The LFE channel isn't nearly as active as it would be in a car unless you're watching something with insane bass. I've been watching Transformers, Iron-man, Jurassic park etc and had absolutely no issues with mine. Mine are mounted to the underside and rear of chairs and they're mostly open, though out of view. I measured them with an IR thermometer during some of the heavy LFE scenes of Jurassic Park and they were only 5 degrees above room temp. If you have them stuffed in a couch or some place that doesn't have a reasonable amount of thermal capacity, you may want to honor the posted wattages.


Parallel vs Serial installations

Lots of people have questions as to the correct method of installation. I found this link earlier in the thread and used it to build the following excel spreadsheet.



The spreadsheet will calculate all the important information simply by putting the specs of your speaker, amp and method of connection. (parallel, series or both) Its calculations are based on 1 channel which means if you plan to hook 3 shakers to your left channel and 4 to your right channel you'll have to fill out the spreadsheet twice. The user fills out the blue section and the red section is calculated.

The info I have displayed is for my current setup. I have 4 standard shakers, 4 ohms each and an amp that is rated at 150 watts at 4 ohms. You could say the amp is a 75 watt amp at 8 ohms and just know that its safe to run it at 4 ohms, the spreadsheet will account for that. As you can see, I could connect all 4 in series and be at 16 ohms for the channel. Almost any amp will handle that. The problem is my current amp will only deliver 9.3 watts per shaker. If I hook 2 of them up in parallel not only does the power skyrocket to 150 watts per shaker but the ohms for the channel drops to 2. My amp is only good down to 4 so that method is out. If I connect each pair in series and then connect the pairs in parallel I get rather good results. The channel is loaded at 4 ohms and all 4 shakers receive a max of 37.5 watts each. (almost like I planned it that way. ) 37.5 watts gives me the ability to drive them up to their RMS yet is still under their peak, should I turn the amp all the way up.

My setup has 2 shakers in series in each chair, and both series circuits go to the amp in parallel. I have RCA connections between the shakers in the second chair and the amp. This way if I need to move chair 2 away from the chair with the amp in it I can simply unplug the RCA cables between the two. My original chair is left with 2 shakers in series which gives me the exact same output as when there were 4 connected.



The load rises to 8 ohms on the channel and the per shaker output is still 37.5. Its invisible to whoever's sitting in the prime chair.

If you'd like a copy of the spreadsheet send me a PM with your email address.

If JL or someone else equally as knowledgeable would like to check my math I'll extend the parallel and series+parallel out to more than 2 and 4 drivers respectively.


Amplifier Used


It seems that most people want to use an old receiver to drive their shakers which is easily feasible should you know the specific properties of each channel. If its more than 2 channel or if it has an LFE output theres a good chance that any LFE signal routed to it could get cut out or unevenly distributed. To keep things easy I'll describe some of the serious gains from using a sub plate amp.

First of all, theres only 1 channel so its very easy to use the above spreadsheet to calculate which way works best for you. Most of them seem to support 4 ohm loads which makes it even easier in many cases to drive your shakers the most efficient way. Almost all have volume control thats easily adjustable. A good portion of them have an adjustable crossover which makes experimenting with performance very easy without the hassle of buying different FMODs or having to swap them in-line. I mounted my plate amp in the bottom of my chair, facing down, so I can simply reach down and modify the volume or crossover while sitting in the chair. Movies like Jurassic Park and Transformers have very good LFE and turning it down near 50hz gives a great effect. Iron-man on the other hand didn't seem to have as much LFE info and I have to turn up the crossover to near 100hz to get what I expect as acceptable feedback. You also don't need long runs of amplified signal since its only a few feet to the furthest shaker from the amp, which means you don't need to calculate the loss to the cable/change in channel ohms. Its easy to run line level feeds to the amp as well.

I also find it easy to do things if you buy your shakers in powers of 2. So 2 shakers is easy to do the math for, so is 4, 8 and 16. Id rather have 8 shakers being run efficiently with equal power distribution than 6 with odd power distribution.

Quote:
Originally Posted by vasyachkin
Even i, the genius, only vaguely understand what i am saying here.
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post #1620 of 2538 Old 10-10-2008, 11:32 AM
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Quote:
Originally Posted by miltimj View Post

spectrumbx, you should be connecting the analog RCA cable from the subwoofer pre-amp output of the receiver, not the digital coax output. Completely different signals (and analog vs digital).

As for limiting the output (which may be an issue even connected to the right output).. if you don't have a sub, you can set the crossover in your receiver to whatever level you want to limit the shaking even further (e.g. 50Hz). If you already have a sub connected to the sub output, then use an RCA Y-cable. You can then get an inline FMOD low-pass filter if you want additional filtering beyond the built-in crossover of the receiver.

Let me know if something above doesn't make sense..

Ok, the sub out from my primary receiver (Y-663) into the secondary receiver (Sony) is not working.
The Sony will work with digital or analog stereo in, but not with the sub out from the Y-663.

Anyone knows why that is?
Also, if I was to go with a FMOD low-pass, it looks like it has to be applied before it gets to the receiver.

That won't work if I am doing digital in.
Am I missing something?
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