Amplifying 4inch speakers to match volume with 6.5inch speakers? - Page 1
Forum section: electronics / projects

author: rwgast_lowlevellogicdesin
author_rank: Frequent Contributor
timestamp: April 03, 2015, 08:50:22 pm
content: I currently run an older but nice sony stereo in my entertainment set up. Most of the time everything sounds pretty good but I have a real problem with the audio dynamics of blue rays discs and the volume of the vocals compared to the volume of the effects. One way I want to solve this problem is to build a center channel speaker, and cross over in the vocal range only.I plan to just build a little box and put a left and right speaker in it, they are only 4inch speakers though, while my bookshelf speakers are 6.5inch.If I used some old twelve watt per channel amp IC to amplify the the the 30watts per channel coming out of the stereo, in order to drive the 4 inch speakers as loud as the 6.5 inch speakers am I going to blow up the 12watt amp? I guess what I want to to do is make the center channel active with its own volume control and im not sure if I can just use a little amp to boost the bigger amps signal or if I need to just build a 40 per channel amp?Ive also considered running resistors inline to the 6.5 inch speakers to lower there volume, but im not totally satisfied with that option.

author: dannyf
author_rank: Super Contributor
timestamp: April 03, 2015, 08:57:49 pm
content: QuoteThe only way to amplify a speaker is to stretch on. Find a few beefy friends of yours and each pulls a corner of the speaker as hard as you can. Before long, you would have amplified a 4inch hspeaker to 6.5inch.

author: Richard Crowley
author_rank: Super Contributor
timestamp: April 03, 2015, 08:58:32 pm
content: What are you decoding the audio with? Are you properly extracting the center channel (where all the dialog is)?Trying to get the dialog from Left and Right is unlikely to be satisfactory.If you want a separate center/dialog channel, suggest using the 5.1 output which has the center channel broken out separately.There are many disk releases that have terrible stereo mixes. Many don't have the center/dialog channel mixed in properly.If you are building a box for a center channel speaker, why use 4 inch drivers? Why do you need 2 of them?There are plenty of plans available on the internet for center-channel speakers with tried and tested designs. What is the motivation for making one from scratch?Amplifying 4 inch speakers to equivalent sound pressure levels from 6.5 inch speakers may push them beyond their linear region.

author: rwgast_lowlevellogicdesin
author_rank: Frequent Contributor
timestamp: April 03, 2015, 10:17:34 pm
content: I want to use the 4 inch drivers because they sound good and I have them on hand. I just plan to use the left and right channel audio one for each speaker and build a filter for about 5000hz to 9000hz that way I can turn up the center speaker a little louder and hear the vocals while the effects are loud. I'm no audiophile using the tvs built in speakers like this works ok but why not use a better pair of speakers in a nice box that will sound better

author: Richard Crowley
author_rank: Super Contributor
timestamp: April 03, 2015, 11:57:30 pm
content: Quote from: rwgast_lowlevellogicdesin on April 03, 2015, 10:17:34 pmWhy is because you stand an excellent chance of achieving exactly nothing. Attempting to extract the center/dialog channel from stereo Left and Right is a losing battle. But feel free to experiment. If you want a better chance of reproducing the dialog, then extract the Center channel from the 5.1 output.If your center channel isn't loud enough, then you probably need more power behind it. If the speakers can't take enough power to hold their own against the Left and Right speakers, then they are not suitable for the project, no matter how good they sound.

author: retrolefty
author_rank: Super Contributor
timestamp: April 04, 2015, 01:02:54 am
content: Speaker size is not a parameter of how large an audio output there will be for a given power supplied to the speaker. SPL is an 'efficiency' parameter that lets you know how much sound volume a given specific speaker at a specific wattage input. There will be some 4" speakers rated for higher sound pressure output at full rated power then some 6 1/2".Good speakers come with datasheets that will tell you all you need to compare among speaker choices.