Latest project update

S Clark · « **on:** 6 May 2009, 12:39 pm »

Whew! Did 8 hours of prelim measurements and crossover building with the kids yesterday . Most of the 2 way speakers went well, but of course, some of the guys wanted deeper bass and tried a 10" three way. We probably spent 2 hours just on that one project and still don't have it right below 300Hz. Some of the two ways have turned out quite nice. The final judging is in about 2 weeks- we'll see how they turn out.

We nearly lost our Clio unit at another high school last Fri.

The old motherboard crashed (not good when the Clio card required about a 10 year old motherboard). No one had anything that old to make it work, but I remembered that I had an old computer under the bed in the back room that my wife had been after me for years to throw away. Yep, it took the Clio and the hard drive and we were up and running again. Hurray for Windows 98 and the DOS Clio.

I go back after school today for round two with that 3 way and a problem 2 way -- will post pictures tonight.
Scott

HAL · « **Reply #1 on:** 7 May 2009, 02:21 am »

Scott,
Sorry to hear the CLIO PC died. Glad to hear that you had a replacement!

Looking forward to seeing the results pictures.

S Clark · « **Reply #2 on:** 7 May 2009, 04:41 am »

OK, here are couple of pics of some of what the kids came up with today. The first group has a GR-Research M130 crossed with an AV123 tweeter- second order on both woofer and tweeter.

The second is a shot of the Clio screen showing the FR graph. It's got a few problems, but its mostly +/- 3 dB.

And last, a pretty darned good curve by one of the kids.

S Clark · « **Reply #3 on:** 7 May 2009, 03:25 pm »

This gal has an Exodus 6.5" donated by Kevin Haskins and a Hi-Vi K1 tweeter from Madisound. She kept trying combos to tame a peak around - ending up with 2nd order on both woofer and tweeter, baffle step correction, L pad, and notch filter- thank goodness Madisound is giving us a bit of a price break. Part of her problems were related to her cabinet and tweeter mounting, but we finally got it +/- 3 dB from about 80 Hz up.

HAL · « **Reply #4 on:** 20 May 2009, 09:51 pm »

Did the speaker competition happen?

S Clark · « **Reply #5 on:** 20 May 2009, 10:23 pm »

Absolutely it happened!

I just got back from Jim Ned High School where Danny Richie and myself did measuring and listening to seven finalist projects- the eighth was disqualified for not being complete. What a day-- long day--- The good is that the three top projects would fit in well at just about any major DIY shootout and surpassed many $1000 monitors. The best of the best were made from Vifa premium, GR-Research, AV123, HiVi, and Exodus (DIYcables) drivers. Most students used 2nd or 3rd order crossovers, most included BSC, and boxes (except for an OB project) well well braced. The bad was that several groups, mostly those doing the project for extra credit versus the school where the project was required, had not finished by the deadline. Their projects will be evaluated this summer.

The top three projects were very, very good. Engaging, realism, air, detail, soundstage, musical.... all of these were there. I'll post pictures later tonight.

Once again, our Clio glitched. We had gotten half way through impedence sweeps when it stopped sending the signal, and we never got it back

Fortunately, I had saved FR graphs on many as we designed the crossovers, but those graphs don't show improvements made in the interum before the deadline. The quality at the top and middle continues to climb from year to year.

Most were traditional box two ways, but the was the pyramidal tetragon with 3 clustered 8" woofers with a HiVi tweeter, in a sort of open box sort of thing. I really couldn't believe that it could work, but it did. It was definitely a speaker that should have failed, except it didn't for the most part, and in some areas succeeded nicely. Then there was the MTM in an open U baffel connect to a subwoofer.

I'll continue the update and post pictures later this evening when I have a bit more time. All in all, it was a good day.

Scott

laserboi · « **Reply #6 on:** 21 May 2009, 04:06 am »

Pictures aren't working for me, is anyone else having problems viewing them?

S Clark · « **Reply #7 on:** 21 May 2009, 05:50 am »

Just haven't gotten them posted. I'll work on it tomorrow morning.

Scott

HAL · « **Reply #8 on:** 21 May 2009, 02:30 pm »

Scott,
The earlier pictures you posted in the thread above are no longer viewable. I cannot see them either.

S Clark · « **Reply #9 on:** 21 May 2009, 03:15 pm »

Hmmmmm..... I don't have a clue. Is this an AC wide glitch with the temporary server, are pictures not available on other threads and circles as well

? I'll see about putting it all right this afternoon- if necessary, i'll go back and redo them all.

S Clark · « **Reply #10 on:** 21 May 2009, 08:23 pm »

It appears that the problem may be with AC in general. When I go back to modify those earlier post, it appears that the pictures are still embedded in them, but they are not showing up

. Also, it looks like the Gallery is not available yet, so sorry guys, no pictures. If it is up and running by tomorrow morning I'll post them, otherwise, they will have to wait til I get back from vacation.

Danny Richie · « **Reply #11 on:** 21 May 2009, 09:23 pm »

Here are some pics of the speakers from my listening chair perspective. I'll let Mr. Clark fill in some specifics about each pair.

Again the top three were very good.

S Clark · « **Reply #12 on:** 21 May 2009, 11:25 pm »

Once again, Danny, I am humbled. How did you get those to post? I have alway taken pictures from the Gallery... and there is no gallery currently.

Oh well. The first picture is an U open baffle MTM with the GR-Research 130-16 with an accompanying subwoofer. Great idea, but the U baffle had pretty severe resonance issues. With more work over the summer, this should become a very solid project.

The second photo was another M130 project with an AV123 tweeter. This one measured out +/- 3dB and worked well overall. We suspect that there was some baffle resonance issues. The crossover was second order with baffle step compensation.

The third photo is a Vifa metal cone tweet with the Parts Express DA-175 Al cone 7" woofer. Really clear deep base, but they never really solved the rather severe breakup modes of the woofer. This one still needs work with the Clio unit (if we can get it working again)

4th photo- M130 with Vifa silk dome
This project worked very well. Musical, articulate, fair imaging and air around the notes. Could have used more baffle step compensation.

5th photo- PE buyout poly cones with AV123 tweeter. Sometimes a kid just wants to do it differently... But to my very real surprise, it sort of worked. Pretty decent vocals, but still had cabinet resonance issues due to lack of bracing.

6th photo- We have a winner!! This little M130/AV123 combo did everything well. Clear, articulate, good bass, musical, imaging, soundstage.... this little speaker did it all. Conratulations to the team of Jordan and James.

7th Photo- And these girls were right behind by a nose. This was the Exodus 6.5" from DIYcables with a HiVi K1 tweeter. Wow, very nice bass, clear mids, with just a touch of sibilance in the upper registers, but not obvious. Just musical, and for me, easy to listen to.

Like all projects, those that put in the time, reaped the rewards. Several of the projects that didn't make the finals also showed work and understanding of concepts.

Thanks to all those that helped make this possible, and congratulations to the kids for doing great work. I think we have some young engineers and designers on the way.

Scott

HAL · « **Reply #13 on:** 22 May 2009, 01:20 am »

Scott,
Very cool indeed! Would have loved to hear the kids comments in real time.

Man, does that preamp and those interconnects look familiar!

Danny Richie · « **Reply #14 on:** 22 May 2009, 01:29 am »

Quote

How did you get those to post?

I didn't put them in the gallery. I uploaded them to the GR Research server.

I think you may have the speaker info on the 2nd and 5th picture mixed up. I know they look a lot alike.

The one in the second photo was this one: "This little M130/AV123 combo did everything well. Clear, articulate, good bass, musical, imaging, sound stage.... this little speaker did it all. Congratulations to the team of Jordan and James."

I will also add that Kevin's Exodus woofers sounded really good, and if those girls would have done a few more tweaks (there were several ways that they could have improved them) they could have easily been the best there. A big thanks to Kevin (DIY Cable) for donating them.

We always get pretty good sound up there on that stage that is surrounded by curtains. The playback system was really good too. It really let the top three really shine.

Danny Richie · « **Reply #15 on:** 22 May 2009, 01:31 am »

Quote

Man, does that preamp and those interconnects look familiar!

It was also a Dodd Audio designed tube amp. We were even using some of the new Electra Cable power cords and a Majik Buss too.

S Clark · « **Reply #16 on:** 22 May 2009, 03:31 am »

Your right about switching those two projects. I might add that the amp was a cloned copy of a prototype that Gary made just for us a couple of years back using iron from a garage full of Fisher 400 and 500 receivers. Several kids and I took the prototype and copied it cap for cap, resistor for resistor. I can guarantee you that those kids now know how to solder and will never forget. They went to college with the best sounding amp of any freshman on campus and plenty of clean power to shake the dorms above and below.

HAL · « **Reply #17 on:** 22 May 2009, 01:35 pm »

Quote from: Danny on 22 May 2009, 01:31 am

Quote
Man, does that preamp and those interconnects look familiar!

It was also a Dodd Audio designed tube amp. We were even using some of the new Electra Cable power cords and a Majik Buss too.

Ok, I know I will have to try the Electra Power Cord and the Majik Buss.

Don't forget the speaker cables.

There is another idea that comes from Scott's last post. If some of the students are DIY building electronics and want a tube preamp kit, the Euterpe Preamp kit that BillP is selling is an entry level single 6J6 dual triode per channel setup. The 6J6 tubes are between $1 and $5 a piece depending on NOS brand and included with the kit. Building one here as a fun project.

Just a thought.

S Clark · « **Reply #18 on:** 22 May 2009, 03:44 pm »

Rich,
I did a brief look around and couldn't find a home site for that preamp kit. What does it cost and where do you buy one? I would like to do more soldering projects since the Dodd amps worked out so well.

Scott

HAL · « **Reply #19 on:** 22 May 2009, 04:38 pm »

Scott,
Here is a link to BillP (billnchristy) thread at the Skiing Ninja website.

http://ninjasreview.com/forum/showthread.php?t=66

The basic kit is $250. You choose the wood for the side panels and the chassis color and finish type.

Not sure how many Bill is going to make. I have the first kit out so far. Django has the first prototype and did post some listening impressions. I am in the build process.

Rich