LumberJocks

speakers for a BT stereo amplifier

  • Advertise with us
Project by harum posted 05-06-2019 07:49 PM 1395 views 3 times favorited 12 comments Add to Favorites Watch

These are small size two-way speakers for the office built to be used with a compact amplifier with a Bluetooth receiver. I built the boxes and ordered other parts from online stores (drivers, tweeters, cables, plugs, crossover parts and the receiver). At the back there is a 5” passive radiator, which are used to impove the sound of the bass end of the spectrum.

The receiver is really small 2” x 4” x 5” in size; the speakers are 9-1/2”H x 7”W x 6-1/2”D each. The boxes are mitered, glued with TBIII.

The woods are chechen for the sides, quilted silver maple for the front and back, lacewood and purple heart as accents. I exposed the purple heart to some sunshine and then let the boxes sit in garage to develop back the bright color. Not sure though if UV helps in bringing the color back; it might be just oxidation.

A simple circle cutting router jig from the Internet was very useful in making holes for mounting the drivers.

The sides are laminated 3/16”-thick bandsaw-cut chechen veneer over cherry as a substrate. These two woods move almost identically in response to changes in the moisture content. This, together with several coats of 1 lb.-cut blond shellac, I believe will take care of seasonal wood movement. Several coats of a wiping poly varnish went over the shellac.

I used free software for all the designs dealing with the volume of the speakers and cusomized crossovers.

Overall, the woodworking part of the project was much harder than the electronics part, which was just using speaker design software and then soldering the parts together. If you asked me, I’d say woodworking takes more skills, equipment, practice and patience!

-- "If you're not counting the ripples when throwing pebbles in the water, you're wasting your time."





12 comments so far

View tbone's profile

tbone

325 posts in 4766 days


#1 posted 05-06-2019 10:12 PM

Nice work. Was the electronics a speaker kit with assembly instructions? Or do you have that skill along with your woodworking skills? I’d like to try to build some stereo speakers, but I know nothing of the electronics. I know there are some kits out there that get pretty good reviews, and I can solder okay. But I would need instructions.
Anyway, again. Nice work.

-- Kinky Friedman: "The first thing I'll do if I'm elected is demand a recount."

View harum's profile

harum

421 posts in 2725 days


#2 posted 05-06-2019 10:45 PM

Thanks, Tbone! Yes, I wanted speakers with specific dimensions, so decided not to use kits thinking I could have more options. Watched some Youtube videos and read two or three diy forums to learn the basics. Once familiar with the terminology and having finalized the design, I used free software that literally creates the schematics, which is simpler than I thought it would be for my speakers (I used 2nd order crossovers, which only need resistors, caps, and inductors).

-- "If you're not counting the ripples when throwing pebbles in the water, you're wasting your time."

View swirt's profile

swirt

6194 posts in 4054 days


#3 posted 05-07-2019 01:06 AM

Very nice looking speakers.

-- Galootish log blog, http://www.timberframe-tools.com

View harum's profile

harum

421 posts in 2725 days


#4 posted 05-07-2019 01:30 AM

Thank you, Swirt! After using them for a bit I believe the sound is worth the trouble. I decided to go for an enclosed amplifier after reading that the aluminum case shields from external interference, which might help with the sound quality.

-- "If you're not counting the ripples when throwing pebbles in the water, you're wasting your time."

View dannmarks's profile

dannmarks

1025 posts in 1663 days


#5 posted 05-07-2019 01:32 AM

This is spectacular. I made my first speakers back in 1974. My brother still has them as I use polypropylene instead of paper cones. The work you did was beautiful. What you did is inspirational and I may make another pair myself. However I will go massive as that makes me happy.

View harum's profile

harum

421 posts in 2725 days


#6 posted 05-07-2019 02:11 AM


This is spectacular. I made my first speakers back in 1974. My brother still has them as I use polypropylene instead of paper cones. The work you did was beautiful. What you did is inspirational and I may make another pair myself. However I will go massive as that makes me happy.

- dannmarks

Thank you, Dannmarks! It would be interesting to see how diy speaker building today compares to the 70s. Someone, for example, mentioned here on LJ that for today’s home woodworking hobbyists much more equipment and materials are available in terms of variety and prices compared to the 70s.

-- "If you're not counting the ripples when throwing pebbles in the water, you're wasting your time."

View Ivan's profile

Ivan

16789 posts in 3949 days


#7 posted 05-07-2019 05:53 AM

Very nice woodworking part of that technical project.

-- Ivan, Croatia, Wooddicted

View Mainiac Matt 's profile

Mainiac Matt

9888 posts in 3410 days


#8 posted 05-07-2019 02:45 PM

Very nice looking speakers…. How do they sound?

Just out of curiosity, what crossover frequency did you use.

On my last build I used 4K ohm and regret it…. wish I had used 2,500 Ohm.

-- Matt -- I yam what I yam and that's all what I yam

View harum's profile

harum

421 posts in 2725 days


#9 posted 05-07-2019 03:36 PM

Thank you Ivan! Thanks Matt! I like how these little guys sound. Crispy enough with a good mid-range; as far as I can hear, the bass from the 4” woofer goes as low as around 100 Hz.

Based on the drivers data, I used 2.5 kHz for the crossover frequency and then adjusted the crossover components to get a relatively flat transfer function over the desired range.

Interesting observation. I’m just a beginner, so curious how the crossover frequency changes the sound. Do you mean some of the frequencies aren’t there?

-- "If you're not counting the ripples when throwing pebbles in the water, you're wasting your time."

View ostap's profile

ostap

93 posts in 842 days


#10 posted 05-07-2019 03:57 PM

Great iob!Thank you!

-- Ostap,UKRAINE I know that I know nothing .SOCRATES www.youtube.com/channel/UC9zSjkAe2FFn4aXUVXjGu6Q/videos?view_as=subscriber

View harum's profile

harum

421 posts in 2725 days


#11 posted 05-07-2019 06:53 PM

Thank you, Ostap!

I tested the speakers through the BT amp with a YouTube 20 Hz to 20 kHz test. I hear speakers starting at 80 Hz through about 12 kHz. Hmm… I guess there’s no way to tell why I don’t hear anything above 12 kHz without the measurements with a microphone. Could be my individual hearing, or could be my crossover desing/build, or could be the BT amp.

-- "If you're not counting the ripples when throwing pebbles in the water, you're wasting your time."

View harum's profile

harum

421 posts in 2725 days


#12 posted 06-10-2019 05:40 AM

The speakers have been doing great so far. It turns out that they can be easily connected to a Google Echo device, too. Well, I tested the lower range with a YouTube test video through BT: the speakers start sounding at about 15 Hz. Pretty impressive range for this simple setup: 15 Hz though at least 12 kHz (don’t hear beyond that).

-- "If you're not counting the ripples when throwing pebbles in the water, you're wasting your time."

Have your say...

You must be signed in to post the comments.

DISCLAIMER: Any posts on LJ are posted by individuals acting in their own right and do not necessarily reflect the views of LJ. LJ will not be held liable for the actions of any user.

Latest Projects | Latest Blog Entries | Latest Forum Topics

HomeRefurbers.com