Sunday, March 28, 2010

Big 2 way DIY loudspeakers with waveguide

This project went from simple testing of vifa xt25 tweeter in 12in parts-express waveguide to finished loudspeaker.
I think most pictures here are self explanatory. One thing to note, this peerless SLS 830669 in it's stock form will not sound good with this crossover. It's cone starts to resonate around 700hz, and it is very audible. Cone treatments that I've applied, significantly reduced this resonance and it's audibility.

Dust caps are removed, top layer (polypropylene?) peeled from cones. Then cones are slit and coated with damping spray. Copper ring (from home depot plumbing supply) glued onto pole piece.

Red impedance curve is before and green curve is after cone treatments.

Preliminary crossover

Speaker is converted from open baffle to sealed. 12in cardboard tube ( for concrete) was glued to the baffle.

Final crossover.
I use these speakers for home theater. They can play loud with great speech intelligibility.

Until recently my main home speakers were ones with scanspeak drivers,
documented below. In process of moving I packed scanspeaks and carried out 
of the basement these speakers and placed them in place of scanspeaks.
Connected them to my favorite HarmanKardon amplifier and was surprised with much
improved dynamics over scanspeaks. Unfortunately I have to part with these speakers due to their size. In terms of sound quality, these may be the best speakers I've built, although I have not compared them directly to my 3 ways.

Wednesday, March 17, 2010

3 way loudspeakers

These are my first 3way speakers. They went through several crossover iterations, the chosen crossover sounds best, obviously :)
Parts used:
0.75 parts-express cabinet (sealed),
tweeter - Usher 9930-20
mid - CSS FR125(early model)
woofer - seas H511

Rear chamber for mid driver is made out several layers of duct tape.

Final crossover, and calculated frequency response.

Tuesday, March 16, 2010

Two way loudspeakers with waveguide

For these speakers I used Seas 27TDFC/TV tweeters, Scan-speak 18S/8531G woofers, 1cft parts-express cabinets and 6.5in MCM waveguide.

These are my main speakers, they have very non fatiguing sound. I can listen to them entire day without getting tired. I use separate amps for tweeters and woofers. I slightly lowered tweeter's amp gain, so if I used single amp, I'd use a bit larger resistor in series with tweeters.


Line array speaker project

These are parts-express buyout drivers. 69c per pair. Part number 309-160  I actually had to tear apart 52 pairs of speakers to pull these drivers out (not all of them are in the picture) :)

Drivers are glued back to back, then hung on a piece of rope, then wired in parallel/series configuration for 5 Ohm. They are configured as dipole (front - push, rear- pull) There is total of 48 drivers per side.

8in away on axis frequency response (FR) and harmonic distortion.

Correction circuit

12ft away on axis array FR

FR of two arrays with correction circuit and OB woofers together, at listening position, about 12ft away.

For a little less than a hundred dollars in parts and shipping, I've made a not bad sounding exotic speaker system :)
Here is my subjective impression of the sound from these speakers. While you are sitting or standing in one spot, sound is very similar to a standard speaker, maybe with a little bit of a full range flavour, just as all full rangers these drivers are forced to play in their resonant region. The big difference from other speakers begins to reveal itself, when you start moving. There is an impression of sound "glued" in space, does not matter where you move, sound remains exactly the same. Tone and loudness do not change.