Rookie DIY project question on tranducers

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Herman T

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Aug 3, 2021
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Hi folks,

I really can use the help. I know next to nothing about electronics. I am trying to add 2 tactile transducers to my massage bed to send waves up to the person sleeping on it. These need not be so strong, just some good vibrations on SPA musics to induce relaxation.

I currently have a basic studio amplifier which I plug in 120V, it's 60HZ and 30 Watts.

So my question is can I put 2: Dayton Audio Tactile TT25-8 Transducer Mini Bass Shakers (8 Ohm).... or shall I go for 16 Ohm? The specs say maximum output is 30W for each of these.
Any information for my attempted setup would be appreciated.
 
those would work. you probably need to mount them to a sheet of ply/mdf and sandwich it between the box and mattress to get it to transmit the bass properly. you could try mounting to to just the box spring but im not sure how well it transmit, i could be wrong.
 
guessing that your amplifier is 8ohms stereo then you should just be able to hook them up like normal if you pick up the 8ohm versions. Have the specs on the amp handy?
 
pendragon1 said:
those would work. you probably need to mount them to a sheet of ply/mdf and sandwich it between the box and mattress to get it to transmit the bass properly. you could try mounting to to just the box spring but im not sure how well it transmit, i could be wrong.
Click to expand...
Yes it needs a surface to vibrate on. Either the frame of the bed or a separate plate. 8 ohm vs 16 ohm is just basically that you need double the amp power to get a similar signal on 16 ohms vs 8 ohms. But you can install two 16 ohm drivers into one channel if your amp is really crappy and can't handle 4 ohm loads. Which from the sound of 30W mains input, it is. That indicates that your real amp power is probably 2x7W and you'll just get big distortion trying to drive those bass transducers. Get a cheap amp that has 2x50W true output minimum.
 
magnetik said:
guessing that your amplifier is 8ohms stereo then you should just be able to hook them up like normal if you pick up the 8ohm versions. Have the specs on the amp handy?
Click to expand...
Was about to post the same.
Moving to a 16 ohm shaker at the same power rating (instead of 8 ohm) has the same effect as halving the output of the amplifier, so an amp of twice the 8ohm power will be needed.
(stating this because its rare to see the 16ohm specs of an amp, they give 4, 6 or 8ohm.)

Also shakers that move a solid metal element tend to initially have a high peak load at the start of each 1/2 cycle and very little load after that.
Amps specced correctly to the same as the shakers max power need dont like this because it pushes them to their limit momentarily.
I wrecked a PA amp using a shaker, even when not pushing it hard on average.
Check peoples experience with the exact shaker you wish to buy and see what amps work without problem, if you want to look for bargains.

>>My advice is overspec the amps power output if you want it to last, limit its max output to avoid damaging the shaker.
This is very easy to do with the Behringer NU DSP amps, they have a full on DSP controller to manage freq response (with superb EQs), power output etc. and can control 2 shakers independently.
I currently use the NU3000 DSP (3KW peak at 2ohms) with a single 8ohm 1KW shaker in bridged mono mode to get more than a single channel will give. A very sturdy amp.
(single channel on my amp at 8ohms maxes around 375W. Bridged mono at 8ohms is 1500W. Those are peak, RMS is around 3/4 of that, so about 1.1KW)

The NU1000 DSP is perfect for small shakers. Its classed as 1000W but thats peak not RMS and into 2 ohms, higher resistance reduces max power output.
The following are closer to the true RMS max figures (on this amp approx 75% of rated peak power):

With 2ohm shaker(s) its probably capable of around 375W RMS into 2 channels (2 separate shakers) = 750W total.
With 4ohm thats 750W bridged or 187W x2.
With 8ohm thats 325W bridged or 93W x2,
With 16ohm thats 162W bridged or 46W x2.
** see Edit2 below, the real figures are probably much lower.
*** bridged mode cannot handle 2ohm speakers. Each amp channel alone can handle 2ohm but when bridged the total minimum resistance is 4ohm.

You can configure the above amp to not give out more power than the shaker is designed for, so overspeccing has no risk.
Oh, and it can be programmed via USB from a PC.

Edit
1) 2x 16ohm shakers can be powered in parallel using a single channel 8ohm amplifier.
ie 16ohm in parallel with 16ohm = 8ohm total resistance.
BUT the amplifier channel must still be able to supply the power needs of both shakers.
So if the shakers are 30W each, the amp channel needs to be capable of at least 2x 30W = 60W. And taking my earlier advice, preferably a lot higher than that.
Also, it doesnt make much sense to get a single channel amp when the most common (hence generally cheaper) are stereo.
The newer Class D amps can handle a lot of power with good efficiency (less wasted power) and lower cost.
Thought I'd spell that out as it could help make a better purchase decision.

2) If you ever need to increase the amount of shakers, care must be taken.
With a single channel or stereo amp and one 8ohm shaker on each channel, adding another 8 ohm shaker in parallel on each channel will bring the total shaker resistance down to 4 ohms on each channel.
Its not common that cheap amps can drive 4 ohms, especially not at high power. Get it wrong and the amp wont last long, the power transistors will just flake.
You can always get another amp if you increase the number of shakers.
Or plan ahead with your first amp purchase, get one capable of supplying enough power for more shakers and handling the lower resistance.
The amp I suggested is ideal.
Although they appear to have updated to a new amp line, NX1000D which has a DSP but I dont know anything more about it yet. i'm not sure if it can be configured using a PC...
... yep, it can be configured with the front display or using a PC.
You can still find the NU1000 DSP if you shop around, hopefully its dropped in price too.

Edit2
It appears the NX1000D has much lower power than advertised. I think the NU1000 DSP is as well but perhaps not quite as bad.
So halve the power figures I stated above.
More info: https://www.audiosciencereview.com/...ringer-nx1000d-review-stereo-amplifier.24908/

To get more power, the 3000W amp is a good buy.
Note, all these Behringer iNuke amps have loudish fans. They can be replaced with a much quieter Noctua. Or house the amp in another room.
 
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Hi folks

I have the specs on my amp. I don’t want to f*** this up. so currently the amp powers 2 x 6 ohm on each chanel. I would like to keep one of the Chanel’s for speakers (for music) and switch the other to the 2 transducers I spoke about. So shall I get 2 x 8ohm or 2x16 ohm transducers for that single 6ohm chanel.

I hope this helps you tell me what ohm transducers to install in serial.
 
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Herman T said:
Hi folks

I have the specs on my amp. I don’t want to f*** this up. so currently the amp powers 2 x 6 ohm on each chanel. I would like to keep one of the Chanel’s for speakers (for music) and switch the other to the 2 transducers I spoke about. So shall I get 2 x 8ohm or 2x16 ohm transducers for that single 6ohm chanel.

I hope this helps you tell me what ohm transducers to install in serial.
Click to expand...
We dont know what amp you have.
Theres not much point you knowing its specs if we dont ;)
 
Nenu said:
We dont know what amp you have.
Theres not much point you knowing its specs if we dont ;)
Click to expand...
Sorry about that. The amp is 15 watt per Chanel, 6 ohm per Chanel. Remember I want to use only 1 of these Chanels for the 2 transducers.
 
magnetik said:
guessing that your amplifier is 8ohms stereo then you should just be able to hook them up like normal if you pick up the 8ohm versions. Have the specs on the amp handy?
Click to expand...

I want to setup these 2 x 8ohm transducers on one Chanel of the amp. Specs for each channel is 15 watt, 6ohm.
 
Herman T said:
Sorry about that. The amp is 15 watt per Chanel, 6 ohm per Chanel. Remember I want to use only 1 of these Chanels for the 2 transducers.
Click to expand...
We still dont know what the amp is.
Chances are it wont work well enough tho, you will lose 1/2 the power.
 
Heh :)
I fear the power supply and output transistors of the amp are already saturated running 1 on each channel, unless it was used pretty quiet.
Putting 2 on one channel may not allow any more power into one channel, giving almost the same effect as just having one transducer.
But if he was using it quietly, it could work.

If we knew what the amp is it might help to determine how much headroom there is.

ps
re my first post, I forgot what the op wrote in the op and rambled on rather lol.
 
Herman T said:
It’s a Yamaha MCR-B142

I appreciate the help. I’m a newbie :)
Click to expand...
https://www.avforums.com/threads/yamaha-mcr-b142-review.1898141/
Unfortunately its rating is 15W/ch at 6 ohms with 10% THD.
Thats probably 12W at 8 ohms.
But 10% THD is not a rating used on anything near good quality I'm afraid so its realistic power figure is a lot less unless you dont mind a lot of distortion.


You didnt give an indication of how loud you use it.
If its quiet you may get away with it.
If not, it probably wont work out well.
You may get lucky.
 
spa music isnt exactly bass-y, not sure how well that will work. you probably just gonna need to get them and try.
 
Yep.
It shouldnt cause damage using 2x 16 ohm.
But 2x 8ohm might harm the amp, not necessarily immediately.
If that channel gives up the ghost one day, this could be the reason.

But...
With the same hifi system, 2x 16 ohm shakers in parallel will produce the same power output of 1x 8 ohm shaker when using the same volume level.
So you might as well stick with one 8 ohm for all the difference it will make.

A better idea is to use another amplifier with its own volume control (to calibrate how much bass you want) with inputs in parallel to the other amp, to drive the shakers, and get 2x 8 ohm shakers.
 
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Nenu said:
Yep.
It shouldnt cause damage using 2x 16 ohm.
But 2x 8ohm might harm the amp, not necessarily immediately.
If that channel gives up the ghost one day, this could be the reason.

But...
With the same hifi system, 2x 16 ohm shakers in parallel will produce the same power output of 1x 8 ohm shaker when using the same volume level.
So you might as well stick with one 8 ohm for all the difference it will make.

A better idea is to use another amplifier with its own volume control (to calibrate how much bass you want) with inputs in parallel to the other amp, to drive the shakers, and get 2x 8 ohm shakers.
Click to expand...


Yes but I have volume control and bass control on this system already. If I go with 2 x 8ohm shall I put lots of base or low base (obviously I will start with lower volume).
 
Herman T said:
Yes but I have volume control and bass control on this system already. If I go with 2 x 8ohm shall I put lots of base or low base (obviously I will start with lower volume).
Click to expand...

I'll quote this again:
But 2x 8ohm might harm the amp, not necessarily immediately.
If that channel gives up the ghost one day, this could be the reason.
Click to expand...
It will for sure destruct faster with more power if it cannot handle 4 ohms, it will harm the output transistors which will sooner or later die.

Thats why I recommend using another amp "alongside" your current setup, just for the shakers.
I very much doubt your amp is designed to handle a 4 ohm load.
 
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That amp frequency response is down to 50hz, those transducers you have are 20-80hz with a resonant freq at 40hz. Not sure what frequency you are trying to use as a massage so that would be helpful info as well. I don;t think the amp you are using will be well suited to fully utilize the shakers.
 
Nenu said:
Was about to post the same.
Moving to a 16 ohm shaker at the same power rating (instead of 8 ohm) has the same effect as halving the output of the amplifier, so an amp of twice the 8ohm power will be needed.
(stating this because its rare to see the 16ohm specs of an amp, they give 4, 6 or 8ohm.)

Also shakers that move a solid metal element tend to initially have a high peak load at the start of each 1/2 cycle and very little load after that.
Amps specced correctly to the same as the shakers max power need dont like this because it pushes them to their limit momentarily.
I wrecked a PA amp using a shaker, even when not pushing it hard on average.
Check peoples experience with the exact shaker you wish to buy and see what amps work without problem, if you want to look for bargains.

>>My advice is overspec the amps power output if you want it to last, limit its max output to avoid damaging the shaker.
This is very easy to do with the Behringer NU DSP amps, they have a full on DSP controller to manage freq response (with superb EQs), power output etc. and can control 2 shakers independently.
I currently use the NU3000 DSP (3KW peak at 2ohms) with a single 8ohm 1KW shaker in bridged mono mode to get more than a single channel will give. A very sturdy amp.
(single channel on my amp at 8ohms maxes around 375W. Bridged mono at 8ohms is 1500W. Those are peak, RMS is around 3/4 of that, so about 1.1KW)

The NU1000 DSP is perfect for small shakers. Its classed as 1000W but thats peak not RMS and into 2 ohms, higher resistance reduces max power output.
The following are closer to the true RMS max figures (on this amp approx 75% of rated peak power):

With 2ohm shaker(s) its probably capable of around 375W RMS into 2 channels (2 separate shakers) = 750W total.
With 4ohm thats 750W bridged or 187W x2.
With 8ohm thats 325W bridged or 93W x2,
With 16ohm thats 162W bridged or 46W x2.
** see Edit2 below, the real figures are probably much lower.
*** bridged mode cannot handle 2ohm speakers. Each amp channel alone can handle 2ohm but when bridged the total minimum resistance is 4ohm.

You can configure the above amp to not give out more power than the shaker is designed for, so overspeccing has no risk.
Oh, and it can be programmed via USB from a PC.

Edit
1) 2x 16ohm shakers can be powered in parallel using a single channel 8ohm amplifier.
ie 16ohm in parallel with 16ohm = 8ohm total resistance.
BUT the amplifier channel must still be able to supply the power needs of both shakers.
So if the shakers are 30W each, the amp channel needs to be capable of at least 2x 30W = 60W. And taking my earlier advice, preferably a lot higher than that.
Also, it doesnt make much sense to get a single channel amp when the most common (hence generally cheaper) are stereo.
The newer Class D amps can handle a lot of power with good efficiency (less wasted power) and lower cost.
Thought I'd spell that out as it could help make a better purchase decision.

2) If you ever need to increase the amount of shakers, care must be taken.
With a single channel or stereo amp and one 8ohm shaker on each channel, adding another 8 ohm shaker in parallel on each channel will bring the total shaker resistance down to 4 ohms on each channel.
Its not common that cheap amps can drive 4 ohms, especially not at high power. Get it wrong and the amp wont last long, the power transistors will just flake.
You can always get another amp if you increase the number of shakers.
Or plan ahead with your first amp purchase, get one capable of supplying enough power for more shakers and handling the lower resistance.
The amp I suggested is ideal.
Although they appear to have updated to a new amp line, NX1000D which has a DSP but I dont know anything more about it yet. i'm not sure if it can be configured using a PC...
... yep, it can be configured with the front display or using a PC.
You can still find the NU1000 DSP if you shop around, hopefully its dropped in price too.

Edit2
It appears the NX1000D has much lower power than advertised. I think the NU1000 DSP is as well but perhaps not quite as bad.
So halve the power figures I stated above.
More info: https://www.audiosciencereview.com/...ringer-nx1000d-review-stereo-amplifier.24908/

To get more power, the 3000W amp is a good buy.
Note, all these Behringer iNuke amps have loudish fans. They can be replaced with a much quieter Noctua. Or house the amp in another room.
Click to expand...
Please note that speakers have resistance and impedance values, which are two entirely different things. The speaker coil has a resistance value and when speaker is driven with an AC signal, it has impedance that varies with frequency. An 8 ohm speaker may have 32 ohms impedance on high frequencies and 2 ohm on low frequencies and vice versa, depending on the implementation.

The Behringer amps are generally awesome for money but the power ratings promised do not reflect reality. A "1000 watt" inuke usually puts out around 200-300 watts per channel to 8 ohms and closer to 1000 watts when bridged to 4 ohms. A 300 watt amp is a bit over kill for a 30 watt shaker, although excess power is never a bad thing. Just cost/benefit factor drops if you pair a cheap shaker with a big amp.

For therapeutic uses a quiet amp is the most logical selection so any hifi integrated amp from a garage sale is a good option (plenty of Yamaha, Pioneer, Denon, Marantz etc. amps rated for 2x50 - 2x100 watts usually on sale for peanuts), or even a Behringer A500 if new is required.
 
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