Speakers

[stevedabear]

I'm a bit of a novice really when it comes to electronics, but i'm making the 18W amplifier from this site. Can anyone tell me where i'd be able to get my hands on some decent 8 ohm speakers ?

Thanks a lot

[audioguru]

Hi Steve,
Welcome to our forum. ;D
I bought my 1st set of decent speakers before I learnt how to make them.
I went to my local stereo shop and listened to many very expensive speakers. Some sounded fantastic to me, while others I didn't like.
Then I listened to less expensive speakers, and only one sounded exactly the same as the expensive speakers that I liked.
I waited about a month for that brand to go on sale then bought a pair.
That was about 40 years ago and I still use them every day. ;D

These speakers have 8" woofers so aren't too big for my living room, but have a reasonable low frequency response. About 15 years ago I realised that I need a sub-woofer like everyone else and made an electronic bass-extension circuit for my speakers. Now visitors ask me where I hide my sub-woofer but I don't have one, it just sounds like I do. ;D

[MP]

Steve, MCM Electronics has a good variety of inexpensive good quality speakers in their catalog. They have been around for a long time.
Another source is wolferstweeters.com

MP

[stevedabear]

Base extension circuit ? So.. did you just create a seperate bass selective amplifying circuit which was applied to the same speakers ? (Wouldn't be my choice for sound quality) or... i dunno lol

[audioguru]

Base extension circuit?

Yeah. My decent speakers are sealed and have a flat response down to their resonance at 60Hz, then their response below falls at 12dB/octave. They have no problem playing with the full power of my amplifier so I made two underdamped Sallen and Key highpass filters with a 12dB/octave increase in level below 60 Hz and a peak of 12dB at 30Hz. Below 30Hz the response sharply drops off. My bass extension circuit matches my speakers perfectly and sounds great.
I did the same trick with boardroom telephone conferencing systems except used an underdamped lowpass filter peaking about 10dB at 3.4KHz. Ordinary boardroom systems sounded muffled and muddy, mine sounded crisp and clear. Everywhere I demo'd it was a sale for me to install. ;D

[stevedabear]

Just out of interest, do you have a circuit diagram, so i can see the full picture. of the bass extension circuit that is. Send to my email [email protected] if you want.

Cheers

[audioguru]

Hi Steve,
I took a standard Sallen-Key highpass filter with a cutoff frequency of about 30Hz, made it for a single supply and made the feedback adjustment of its Q or damping, adjustable. When the slider of the pot is lowered on the schematic then bass frequencies are boosted around its cutoff frequency. The resistor in series with the pot prevents too much boost to prevent oscillation.
Sorry, I can't find my original plans to give you component values and I don't want to take apart my stereo to see. So this schematic  for 1 channel has its formula. ;D

[stevedabear]

ahh i see,  ;D simpler than i imagined ;D

[cobrakai]

try radioshack?

[audioguru]

I have taken 3 different RadioShack speakers that didn't sound too bad and threw-out their garbage cone tweeters, replacing the tweeters with good dome ones.

Then I also threw-out their garbage single capacitor which was called a "crossover network" and replaced it with 2 coils, 3 capacitors and 2 resistors for a real crossover network.

Then I designed and installed tuned ports for  ;D