Amplifier too loud

[vweber]

Hi guys,

I´m new in speaker building and I hope you can help me with a problem.

I´m currently working on a couple of simple full-range Bluetooth speakers I want to build for a cabin we have in here in Mexico.

I have been doing some tests with different types of amplifiers, speakers and power sources, but it doesn't matter what combination I use all of them are really loud and start to distort at half the volume.

The biggest issue is that we are renting the cabin for the weekends and holidays and everybody that rents the house will have access to the speakers so I know some of them will play music at full volume and I don´t think the speakers will last.

I´ve been taking some measurements of the voltage of the output of the amplifiers to calculate the RMS watts each amp is giving and none of them go higher than 15 watts and all of the speakers I have are at least 30 watts RMS.

Here is a list of all the components I´ve been testing.

Speakers:
- Dayton Audio PC83-8 3" Full-Range Poly Cone Driver
Dayton Audio PC83-8 3" Full-Range Poly Cone Driver

-Dayton Audio PC83-4 3" Full-Range Poly Cone Driver
Dayton Audio PC83-4 3" Full-Range Poly Cone Driver

-Dayton Audio TCP115-4 4" Treated Paper Cone Midbass Woofer 4 Ohm
Dayton Audio TCP115-4 4" Treated Paper Cone Midbass Woofer 4 Ohm

-FaitalPRO 4FE32 4" Neodymium Professional Full-Range Woofer 8 Ohm
FaitalPRO 4FE32 4" Neodymium Professional Full-Range Woofer 8 Ohm

Amplifiers
- TPA3110D2 2.1 Channel Bluetooth 4.1 Digital Amplifier Board 2 x 15W + 30W with Volume Controls
TPA3110D2 2.1 Channel Bluetooth 4.1 Digital Amplifier Board 2 x 15W + 30W with Volume Controls

- KEYREN Power Amplifier Board, Digital 2.1 Channel Amplifier Board Bluetooth USB TF Input 50W+50W Stereo 100W
https://www.amazon.com/-/es/KEYREN-...etooth+amplifier+module&qid=1585454385&sr=8-9

-Cuawan ZK-502L Mini Dual Channel Stereo Amplificador 5.0 Bluetooth Amplifier Board Wireless Digital Power 2 X 50W
https://www.amazon.com/-/es/ZK-502L...tooth+amplifier+module&qid=1585454817&sr=8-12

- AOSHIKE DC12V-24V 2.1 Channel TPA3116 Subwoofer Amplifier Board High Power Bluetooth Audio Amplifier Board 50W+50W+100W (Bluetooth Amp)
https://www.amazon.com/-/es/DC12-24...&sr=1-52-dd5817a1-1ba7-46c2-8996-f96e7b0f409c

Power source

- 12V 1Amp

-15V 4Amp

-18V 3Amp

Is there an easy way I can limit the volume or gain on the amplifiers?

 

[Yatsushiro]

The fact that you are having trouble with every combination suggests your issue is elsewhere; your source perhaps?

I have used the same amp as the Cuawan you listed, without issue on some Mission 760 and QAcoustic 3020 without issue, but these are larger speakers.

I use the following in some reworked vintage radios, driving internal FaitalPro 3" and 4" speakers, and also with the aforementioned Mission and QAcoustic speakers. Despite the low voltage and wattage, sound quality and volume is surprisingly good. Mated with a 5v BT module, it works very well for small outlay.

https://www.amazon.com/-/es/2001711002/dp/B077MKQJW2/ref=sr_1_1?__mk_es_US=%C3%85M%C3%85%C5%BD%C3%95%C3%91&dchild=1&keywords=pam8406&qid=1585476989&sr=8-1

https://www.amazon.com/-/es/dp/B07P94Z9XR/ref=sr_1_3?__mk_es_US=%C3%85M%C3%85%C5%BD%C3%95%C3%91&dchild=1&keywords=bluetooth+module&qid=1585477161&sr=8-3

https://www.amazon.com/-/es/Niubow-Bluetooth-decodificador-bricolaje-inal%C3%A1mbrica/dp/B07Z6KB4H1/ref=sr_1_16?__mk_es_US=%C3%85M%C3%85%C5%BD%C3%95%C3%91&dchild=1&keywords=bluetooth+module&qid=1585477350&sr=8-16

 

[Douglas Blake]

I have been doing some tests with different types of amplifiers, speakers and power sources, but it doesn't matter what combination I use all of them are really loud and start to distort at half the volume.

That's pretty easy to fix, just add an attenuator at the input. A couple of simple resistors will do the job quite nicely per the thumbnail. You can hide it away inside the casings so nobody can get at it. You may have to experiment with different values of resistors until you get a good result. As shown it will provide about 10db of attenuation...

 

[vweber]

Thanks, Douglas, I will try with different values to see what happens.