Adding 3rd seaker to 2 channel amp? (Fixing lack of bass)

Thread Starter

Superking75

Joined Nov 21, 2018
2
Forgive me if this question has already been asked. I personally have not been able to find anything solid after scouring Google. Also, sorry for the botched title.

I am currently looking into the idea of building a semi-portable Bluetooth speaker out of a homemade 2-channel audio amplifier circuit (see attached). My current issue is that it noticeably lacks bass. An issue caused by the fact that my two "full ranged" speakers only operate down to 130hz.

My thoughts are to use a low pass filter to connect a woofer that can operate at a lower frequency, though I'm not exactly sure as to how it would be done. Is it possible? Is there another way I could solve this?

Current speakers: https://www.mouser.com/ProductDetail/Visaton/FR-7-4-Ohm?qs=/ha2pyFadujmkTcblL6XBAkzt692O3vfI4CBJotc3Rqx7ulyQ56l8g==
Hypothetical addition: https://www.amazon.com/DROK-Loudspe...i=B01J5P77UG&refRID=817S29ESVVHJJW8PV18W&th=1
 

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Thread Starter

Superking75

Joined Nov 21, 2018
2
I would look into sub-woofer speakers.
SG
I have to an extent. My issue with true subs comes in with the fact that all the ones I've seen are either to big, or to expensive. (Smaller than 4 inches and preferably Bellow $25)

Though that would still require a way of attaching it to the amp with the other speakers.
 

sghioto

Joined Dec 31, 2017
4,205
I have to an extent.
I lot of the response and/or efficiency is also in the design of the speaker cabinet.
Though that would still require a way of attaching it to the amp with the other speakers.
No problem. Use a stereo chip like a TDA2005 that you can bridge. Combine left and right channel through a buffer, feed this through a low pass filter and then connect to amp.
SG
 
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MrChips

Joined Oct 2, 2009
28,528
First thing to check: make sure your two (or more) loudspeakers are wired in-phase.
If speakers are out-of-phase, the bass notes will cancel hence resulting in reduced bass response.
 

wayneh

Joined Sep 9, 2010
17,273
I think your larger problem is power. The lower you want to go, the more power you need, and I mean a lot more. Unless you have a beefy power supply, you may be chasing your tail. That said, some of the well designed products out there do a surprisingly good job.
 

crutschow

Joined Mar 14, 2008
32,070
An issue caused by the fact that my two "full ranged" speakers only operate down to 130hz.
The 90Hz response of your referenced 3" subwoofer would not help that a lot.
Can you use something a little larger (at least 4", or perhaps 5" or 6")?
Look at Parts Express, as they carry a good selection.
Look for one with high efficiency (dB out per watt) to minimize the amp requirements. Remember a 3dB increase in sensitivity equals a halving of the required amp power for a given audio level.
For reasonable bass, you would likely need an amp of at least 10-20Wrms.
And, of course, it must be placed in a proper bass reflex speaker box designed for the speaker characteristics to get good bass.
 

Audioguru

Joined Dec 20, 2007
11,248
Bose made a little Bluetooth stereo speaker that amazed me with its good sound and its very high price. I told my son so he bought me a much cheaper one from China. The Chinese one has no bass and does not go loud enough

I agree that the tiny 3" speaker will not produce much bass unless you boost it and use a high battery voltage for its added amplifier, but then the battery will not last long.
 
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