Boosting audio

[scarr999]

Hi All,

I have a DY-SV5W and a 50ohm 8w speaker build into an animatronics puppet I want the maxim volume possible, so how can I boost the 5W to 8W easily? also can I overdrive the 8w speaker (I imagine it will degrade the quality)

Thanks

P.S. A variable output would be great 8w-15w so I can set it at the best level if this is possible.

[Zero999]

50 Ohm is a high value impedance for a speaker. You could change it to 8 Ohm, for more volume.

[Xena E]

Agree.
Those modules are able to drive a 4ohm load, and 5Watts through a decent speaker will be earsplitting.

[scarr999]

Hi,

Unfortunately changing the speaker isn't easy as it's embeded in the puppet.

[wasedadoc]

Are you sure about those speaker numbers? 8W into 50 Ohm requires 20 Volts rms which is 56 Volts peak to peak.

[Gyro]

What is the diameter of the speaker?

[scarr999]

Are you sure about those speaker numbers? 8W into 50 Ohm requires 20 Volts rms which is 56 Volts peak to peak.

Hi,

That's what the Chinese puppet manufacturer stated when I asked him, but they haven't been the most reliable

[scarr999]

What is the diameter of the speaker?

I don't know as I can't get at it, it's built into the head, I'll try to get this info, the head is about 70mm x 110mm if this helps.

[Gyro]

My guess is that it is a standard 50mm round speaker then. That would account for the 50 and 8w references ('w' is sometimes used as an alternative for ohms on imported stuff), so 8 ohms. You can check this with a DMM on resistance range - 8 Ohm speakers typically read about 6 ohms at DC.

Such speakers are typically rated at 0.25W - 0.5W. Over-driving them to any significant extent will not only cause serious distortion but risk burning out the voice coil. My suggestion would be to arrange some form of concealed sound reinforcement system with a bigger speaker.

[CaptDon]

I agree that 50 ohms doesn't seem correct. It may have been chosen to obtain long battery life at the sacrifice of much lower volume. As a previous poster suggested, measure the D.C. resistance of the speaker. Multiply the D.C. resistance by a factor of roughly 1.2 and that will be the rated 'impedance'. Also, going from 5 watts to 8 watts is useless. To the human ear an increase of 4 to 6dB SPL (power) is required to sense a 'twice as loud' volume level. 6dB is 4X the power. You would have to go from a real 5W to 15+ watts to double the apparent volume. A previous poster also stated that 5 watts is very loud with a good speaker which is true. However, I am guessing the speaker in the puppet is probably less than 80dB 1 watt / 1 meter with a very poor frequency response curve and probably choked down another 10dB by its placement within the puppet. This will require careful planning to get a meaningful positive outcome. Cheers mate, best wishes!!

[scarr999]

My guess is that it is a standard 50mm round speaker then. That would account for the 50 and 8w references ('w' is sometimes used as an alternative for ohms on imported stuff), so 8 ohms. You can check this with a DMM on resistance range - 8 Ohm speakers typically read about 6 ohms at DC.

Such speakers are typically rated at 0.25W - 0.5W. Over-driving them to any significant extent will not only cause serious distortion but risk burning out the voice coil. My suggestion would be to arrange some form of concealed sound reinforcement system with a bigger speaker.

Thanks to everyone who has replied. When you say "bigger speaker" do you mean physically or W? and being a total novice at all this speaker stuff, I'd appriciate a like to the speaker you think would give me a good volume with the 5w audio module. Cheers

[Gyro]

I was thinking external, I don't know anything about your setup but a small cabinet speaker concealed (behind a back cloth?) a little way behind the puppet. It sounds as if you're going to have some difficulty opening the head and I don't think you'll have much luck making a difference. The problem is that (assuming optimal acoustic design of the head) it is so small that out-of-phase sound from the rear of the speaker cone combines and cancels sound from the front (for all but high frequencies) making it very tinny. Completely sealing the space behind the speaker would would yield a volume too small to allow lower frequencies (tinny again).

Theoretically you could add sound equalization (a filter network before the input of the amplifier), really boosting low frequencies and attenuating high, but you would need lots of power and a specialist speaker unit. The head would probably vibrate significantly.


Edit: Seeing the internal construction might help... if you can do it without damage, I suspect significant amounts of glue are involved.

[janoc]

Thanks to everyone who has replied. When you say "bigger speaker" do you mean physically or W? and being a total novice at all this speaker stuff, I'd appriciate a like to the speaker you think would give me a good volume with the 5w audio module. Cheers

You can't really get good performance and high power out of a small speaker. More power = more current through the coils = more heat = smoke escaping. There is no way to work around the physics there. 

There is also a matter of sound pressure - a speaker with a larger diaphragm will generally be (a lot) louder and better sounding than a tiny speaker, even though you are pushing the same power through them. Simply because the larger area moves more air. So if you want to make things louder, making the speaker larger is your first thing to attempt.

[MarkT]

Clearly the speaker is nominally 50W 8 ohm, not 50 ohm 8W (50 ohm speakers are not a thing, they are 4/8/16/32 typically).  But 50W is probably a spurious "music power" rating, basically meaningless.

For good bass you need either a large volume speaker enclosure, or a ported enclosure and a less efficient speaker driver.  The proper way is to obtain the Thiele-Small parameters for the driver and do the calculations to select enclosure and port sizes.  Or trial and error, with a range of different drivers.  Or buy a complete speaker, not just a driver.

[Gyro]

Clearly the speaker is nominally 50W 8 ohm, not 50 ohm 8W (50 ohm speakers are not a thing, they are 4/8/16/32 typically).  But 50W is probably a spurious "music power" rating, basically meaningless.
...

50W in a 2" speaker?  That would have to be very spurious, even the China sellers on ebay don't claim that!

[Zero999]

I can confirm that 50 Ohm speakers do exist. I've got one in my junk box, I salvaged from an old telephone with a speaker phone.

The obvious solution would be a transformer. A mains transformer with a 120V primary and 30V secondary could be run in reverse to reduce the impedance of the speaker to just under 4 Ohms.

Note that a 120V:30V transformer will really be 120:33 or more. Also, the transformer will need to be significantly de-rated, to account for the fact that audio goes down to 20Hz, so it can only be used with 10V RMS in.

[scarr999]

Clearly the speaker is nominally 50W 8 ohm, not 50 ohm 8W (50 ohm speakers are not a thing, they are 4/8/16/32 typically).  But 50W is probably a spurious "music power" rating, basically meaningless.

For good bass you need either a large volume speaker enclosure, or a ported enclosure and a less efficient speaker driver.  The proper way is to obtain the Thiele-Small parameters for the driver and do the calculations to select enclosure and port sizes.  Or trial and error, with a range of different drivers.  Or buy a complete speaker, not just a driver.

When you say "making it larger" you mean changing the speaker for a larger 5w 4Ohm to work with the DY-SV5W

[CaptDon]

I concur, 50 ohm speakers do exist. I have seen them in very old headphones that used a speaker that looked like it can from a small transistor radio. Granted, they are unpopular. The headphones came with home stereo equipment that had no internal level reducing resistors for the headphone jack. It was a way of limiting the available headphone power and SPL.

[Calvin]

Hi,

#9, CaptDon:

To the human ear an increase of 4 to 6dB SPL (power) is required to sense a 'twice as loud' volume level. 6dB is 4X the power.

These figures are actually incorrect. A clear discrimination of loudness can be sensed at +3dB of SPL ... sensitive ears can discriminate lower levels.
A sensed doubling of loudness requires about +10dB of SPL, resp. a power factor of 3.16.
So doubling power doesn´t equal double loudness!

regards
Calvin

[CaptDon]

Most folks can perceive an increase in loudness at 1dB. A 3dB increase is most definitely noticeable by everyone. 6db is where most listening audiences say the volume has doubled. In this case we are speaking about measurements made using a pure single tone sinewave. Granted, with music it is more subjective and the increases may have to be greater than those stated above. This data is presented in most sound engineering handbooks.

[Calvin]

Hi,

no Sir!
+6dB increase in SPL is not a factor of 2, resp. +6dB increase in sensed loudness.
It´s a generally accepted rule-of-thumb that +10dB in SPL relates to a doubling of sensed loudness.
Whereby it should be noted that sensed loudness is a measure coming from Psychoacoustics (defined by Stevens, 1936).... as such it doesn´t correlate exactly with the physical measure of SPL and varies, depending on intensity, frequency range/resp. kind of ´acoustic phenomen´, time, etc.
See also: https://sengpielaudio.com/calculator-loudness.htm

regards
Calvin
 

[themadhippy]

Just put a bigger speaker stack in and everybody will think its  louder