Introducing the SSA-WG

[agrippa]

I might be off, but I have done some finishing over the years and I like a thinned polyurethane. My kitchen cabinets, dinning room table, chairs, and a couple other things have it on it and you can hardly tell it is there. I thinned it enough to have almost no shine/plasticy look. I also like it for the lack on maintenance. But if you go for a tung oil be prepaired to oil it once and while. I have a few pieces that I have used an oil finish on... And they need regular maintenance even if I don't use them. Oil finish is nice looking but I have replaced it on one major project because of the maintenance issue. Temperature and humidity could also be a factor.

I highly recommend this book. It busts many myths about wood finishing that presist in many places on the internet. It covers all major and many minor finishes and the best techniques for applying them. For $15 it is worth it for anyone who finishes even one nice set of speakers. It covers many types of oil and you may find it useful.

http://www.rockler.com/understanding-wood-finishing-book?utm_source=google&utm_medium=cpc&utm_term=&utm_content=pla&utm_campaign=PL&sid=V9146&gclid=COqFm4-Eoc4CFZSIaQodfzgL2w

some poly myths busted here in case you want it.

http://www.popularwoodworking.com/article/the_7_myths_of_polyurethane

Stick with oil if you are set on it and don't let some jerk on the internet sell you on poly just because he says it is great.

[sdl2112]

I might be off, but I have done some finishing over the years and I like a thinned polyurethane. My kitchen cabinets, dinning room table, chairs, and a couple other things have it on it and you can hardly tell it is there. I thinned it enough to have almost no shine/plasticy look. I also like it for the lack on maintenance. But if you go for a tung oil be prepaired to oil it once and while. I have a few pieces that I have used an oil finish on... And they need regular maintenance even if I don't use them. Oil finish is nice looking but I have replaced it on one major project because of the maintenance issue. Temperature and humidity could also be a factor.

I highly recommend this book. It busts many myths about wood finishing that presist in many places on the internet. It covers all major and many minor finishes and the best techniques for applying them. For $15 it is worth it for anyone who finishes even one nice set of speakers. It covers many types of oil and you may find it useful.

http://www.rockler.com/understanding-wood-finishing-book?utm_source=google&utm_medium=cpc&utm_term=&utm_content=pla&utm_campaign=PL&sid=V9146&gclid=COqFm4-Eoc4CFZSIaQodfzgL2w

some poly myths busted here in case you want it.

http://www.popularwoodworking.com/article/the_7_myths_of_polyurethane

Stick with oil if you are set on it and don't let some jerk on the internet sell you on poly just because he says it is great.

Thanks for the info...I actually have that book. I'm kind of doing what you suggest. I'm thinning the Arm-R-Seal and adding oil for penetration and workability. It should still retain adequate durability.

[JonMarsh]

BTW, another product to consider, given the finishing technique you want to use (though lord only knows you've got lots right now, you might was well open a store...) is Minwax wipe on poly. Your explanation of what you wanted to do mirrored my goals for the Isiris, - I was working with bare LBL ply. Worked like a charm, looks good, easy to apply and holds up very well.

[sdl2112]

I've been working on a bunch of behind the scenes stuff. Now finally some deliverable progress. :T

I took yesterday off partly because we have a use it or loose it PTO policy now....and I wanted to see how the first coat of varnish goes...very anxious.

During testing I lost count of how many times I had to take the drivers in and out of the cabinet. I'm not using wood inserts but this proves the bamboo holds threads very well, no issues of them wearing out. That said shellac is a good wood hardener so I dripped some in each driver hole with a coffee straw for added strength.


I rough sanded with 80 grit and made temporary cabinet feet.


I completed the speaker turntables and continued with sanding.


Over the last couple weeks I've been trying different finishes. I focused on a vanish or oil/varnish blend. It got a little out of hand 8O...I tried boiled linseed oil, tung oil, polymerized tung oil...alone, under and blended with varnishes...etc. I tried urethane, phenolic and alkyd varnishes. I was focusing on looks and ease of application. I elected to go with Pratt and Lambert 38, a clear soya alkyd varnish. I read good things about its clarity, less yellowing and less of a plastic film look compared to polyurethanes. Waterlox looked good also but was a little darker. I would like to try it on a darker wood. I started out diluting it 50/50 with mineral spirits for a wipe on application.

[sdl2112]

I had issues with test finishing in the garage. The temperature and humidity changes were causing the finishes to bleed out and tack up quickly. I decided to apply it indoors. There would also be less dust. The fumes were not bad for the test pieces but likely would be with both speakers. Bob made a good suggestion of segregating the work piece if possible to keep the odor down. My laundry room was the perfect location. I made a small exhaust fan to place in the window and it worked great. I left the house and when I came back I could hardly detect any odor.:T

Fan in place, ready for varnish.


Varnish/Laundry room.


First set of varnish coats applied. I'm going with a schedule of 3 light coats per set about 1 hour apart. One set of coats every couple days with light sanding in between...we'll see how it goes.

[Steve Manning]

See what happens when you have more than one choice ....... Looking good Scott. Do I see a portable ac unit for the garage in your future?

[Face]

Nice job, they look great!

That fan looks like the exact one I removed from a Crown amp.

[sdl2112]

See what happens when you have more than one choice ....... Looking good Scott. Do I see a portable ac unit for the garage in your future?

Thanks Steve. Believe me I was tempted...They had them on display at HD but I need to quit spending money :B

[sdl2112]

Nice job, they look great!

That fan looks like the exact one I removed from a Crown amp.

Thanks Face. I was a little concerned wiping a surface this big...so far so good.

This little fan really blows...surplus from work, rated for 105CFM.

[sdl2112]

I'm glad to finally have an update. The finishing process is an art in itself. I am relieved, I just finished...I think. As Ron said before...I've had enough fun, it's good enough. I started with clear gloss varnish then switched to satin for the final coats. I was just going to build with the clear but the pores remained unfilled and bringing it back down to satin would leave shiny spots. So I switched to satin for the last 6 coats. All in all I applied 20 wipe on coats. Sounds like a lot but wipe on coats are very thin but leave a very good finish.

I waited 3 weeks before rubbing out the final finish. I was very nervous of sanding through the finish and having to start over. Luckily all went well. For the final rub out I leveled with P800 grit paper with a sponge sanding block then moved on to 1000 then 2000 Mirka Abralon sanding discs, wet sanded with my orbital sander and by hand. Highly recommended.

Here sanding between coats with Abralon 500grit


Finished...






I also ordered x-over parts back in August. The package ended up in parcel space somewhere but ultimately made it to the USPS recovery center where the correct address was found. This order includes components I'm pretty sure of, some of the more expensive one's I'll order later once a mock-up is tried.

[flamethrower1]

Cabinets turned out very nice, love the finish.
Looks more like polished wood rather than plastic coated wood.
Very nice job

[dar47]

Wow Scott, beautiful job on the finish the satin is perfect:T:T

[Steve Manning]

Very nice Scott ...... nice to see the sheen stay where you wanted it. I have become a fan of satin since doing the Minerva's and your is looking killer.

[wkhanna]

nice.
V nice!

[sdl2112]

Cabinets turned out very nice, love the finish.
Looks more like polished wood rather than plastic coated wood.
Very nice job

Wow Scott, beautiful job on the finish the satin is perfect:T:T

Very nice Scott ...... nice to see the sheen stay where you wanted it. I have become a fan of satin since doing the Minerva's and your is looking killer.

nice.
V nice!

Thanks everyone! It's not perfect but from the couch view it will be fine. There's some waviness and scratches upon close inspection. The scratches would have taken more sanding and buffing but I wasn't going to take the chance.

As I was moving them past the sunny doorway it gave me a chance to take some natural light photos. The first two show the closest real color, some of the closer shots are a little too rich in color. One thing the photos don't show is how smooth they are. The top feels like a new waxed car...:T

[ergo]

Very very nice looking. Something to wait for is to see the pretty drive unit in them as well.

[JonMarsh]

Very nice looking, Scott- you have much reason to be proud of how these have turned out with all your hard work! :T

No progress for me on speaker stuff; I'm eating lunch right now in Vancouver WA on my way to Tacoma, then Seattle Monday morning.

[5th element]

Well I've certainly missed a lot here, those are looking fantastic!

[sdl2112]

Very very nice looking. Something to wait for is to see the pretty drive unit in them as well.

Thanks ergo...I am really looking forward to see drivers and the base installed.

Very nice looking, Scott- you have much reason to be proud of how these have turned out with all your hard work! :T

No progress for me on speaker stuff; I'm eating lunch right now in Vancouver WA on my way to Tacoma, then Seattle Monday morning.

Thanks Jon...It's neat how the project is evolving.

I hope you will have time soon on your project.

Well I've certainly missed a lot here, those are looking fantastic!

Thank you too Matt...Congratulations on your website. I look forward to checking it out!

[meb46]

Very nice work, they look fantastic!

[wkhanna]

OT, but Matt, your website is looking V good!

[sdl2112]

I can't believe it's been almost 2 yrs since my last update. There are these life distractions and the next thing you know time flies by. Now I'm on the home stretch. The last couple weeks I've been working on the prototype crossover, doing tweaks and optimizations. I have both up and running and they sound fantastic. This is with some lower quality parts. There are more things I want to try but here are photos of progress thus far. I'll have more measurements when time permits.

Here's adding the base for testing.


Initially I tested on a table to help reduce room reflections






Here's measurement at 2M, 15 deg off axis when on the table with 10ms and 200ms gating.

[Steve Manning]

Hey Scott .... 2 years, wow that's crazy already. Good to see you active again.

[scottvalentin]

I remember following this - wow 2 years. As Steve said, glad to see you getting to the finish line on these, you did a beautiful job on the cabinets!

[sdl2112]

Thanks guys....I’m glad to be making progress again.

[Dave Bullet]

They look fantastic! Nice on axis response too. can't ask for much better. Have you found any "problem" tracks? I'm working on a 3 way and some tracks make the tweeter (with my 2KHz LR4 acoustic crossover) jump out and get all forward and angry. I wonder whether it is just the recording and they are being all too "revealing" lol.

[sdl2112]

Thanks Dave, I just got them up and running Monday afternoon so still working things out. I need to move some obstacles in the room and optimize room placement. No problems stand out yet. I also plan to try Jon's voicing circuit.

[jim1961]

They look fantastic! Nice on axis response too. can't ask for much better. Have you found any "problem" tracks? I'm working on a 3 way and some tracks make the tweeter (with my 2KHz LR4 acoustic crossover) jump out and get all forward and angry. I wonder whether it is just the recording and they are being all too "revealing" lol.

Just a guess on my part, but I would look at the phase response.

I say this because unusual or odd location of things in the soundstage can often be traced to nonlinear or a lack of smoothness in the phase response. Timing/phase is what allows for the illusion of placement in the soundstage in the first place. So hunt for sudden changes in the frequencies in question.



Here is what mine look like unsmoothed just for reference at the listening position (Red = right channel, Gray = left). Also is good for L & R to lineup closely.

Note: If you have strong room reflections, things can get mucked up in a hurry.

[jim1961]

Great job Scott!

[Dave Bullet]

Thanks Jim. That's good advice. I'll take a closer look at phase. I have noticed the transfer function of the tweeter has a sharp cutoff / knee. This could lead possibly? To ringing or some anomaly around the upper midrange / lower treble to which we are most sensitive. I'll try a gentler slope playing the tweeter alone to see.

[sdl2112]

Hey Dave...please post your results and good luck!

[sdl2112]

I have a few updates. I think the xover is very close to being finalized. At least until I find something else to fiddle with . I have simplified it a little from the previous version but not much has changed. There is very good correlation between simulated and measured. Below is the latest...I'm calling it rev 3.3.


Here are all drivers with the mid connect in and out of phase.


Next is the target and driver responses. I selected 2M at 15 deg off axis for optimization.


Next shows the transfer functions.


Here is the overall impedance.

[sdl2112]

Now some measurements. The previous plot was on the elevated table near the middle of the room. I'll show measurements at the listening position. First are quasi near field measurements of each driver. I'm trying to get each driver response without room reflections to validate the xover function. Below shows the measurements.


Here is the 0, 15, 30, 45 and 60 deg off axis response at 58 inches


The next curves are the left and right responses at the seating position. It's approximately a 7.5ft equilateral triangle. This wasn't the original room I had planned for these but it was becoming impossible to place these in the living room without blocking the TV. I may try it there later. Any way it is a pretty small room and there are no room treatments...yet, we'll see. I initially started with the Cardas room guide for the ratio from the rear wall to the side wall. This yielded more mid-bass and less deep bass then I was hoping. Moving it back from 59" from the back wall to 41" improved it quite dramatically, it may not look that substantial but it is. I made incremental measurements for the distance and I'm still working on that, there are always trade-offs. Below I show 59 inches (red) and 41 (green). I placed the speakers on furniture sliders which helped out a lot. It looks like all frequencies are there but room treatment should help with the peaks and valleys...one thing at a time though. In the latest position they sound quite impressive. I have 400W available and they can take quite a lot of power. Imaging is good, mid, base and highs are better than I have heard in my house. It's like I'm looking (hearing) through a cleaner window. Every aspect just seems more clear and real.

Enough for now.

Left


Right

[Hdale85]

Hmm this is a great looking design, went to look at what the driver costs are now days and boy I bet it's gone up quite a bit from 2 years ago lol. Would love to do something like this for a 2 channel setup downstairs in an emptyish room we have.

[Dave Bullet]

Hey Dave...please post your results and good luck!

I will do but will post in my own thread so as not to hijack your build post.

My mic pre-amp has had a failure (+48v phantom circuit has burnt out) so will need to sort that first.

[jim1961]

The next curves are the left and right responses at the seating position. It's approximately a 7.5ft equilateral triangle. This wasn't the original room I had planned for these but it was becoming impossible to place these in the living room without blocking the TV. I may try it there later. Any way it is a pretty small room and there are no room treatments...yet, we'll see. I initially started with the Cardas room guide for the ratio from the rear wall to the side wall. This yielded more mid-bass and less deep base then I was hoping. Moving it back from 59" from the back wall to 41" improved it quite dramatically, it may not look that substantial but it is. I made incremental measurements for the distance and I'm still working on that, there are always trade-offs. Below I show 59 inches (red) and 41 (green). I placed the speakers on furniture sliders which helped out a lot. It looks like all frequencies are there but room treatment should help with the peaks and valleys...one thing at a time though. In the latest position they sound quite impressive. I have 400W available and they can take quite a lot of power. Imaging is good, mid, base and highs are better than I have heard in my house. It's like I'm looking (hearing) through a cleaner window. Every aspect just seems more clear and real.

Enough for now.

Left
[ATTACH=CONFIG]28509[/ATTACH]

Right
[ATTACH=CONFIG]28510[/ATTACH]

Looks real nice there Scott. Are you aiming for a flat response? What I mean is many prefer a tilted response where from 50-10k, the response drops off the highs in reference to the lows at about 1db/octave. This of course is a purely subjective preference.

Anyway, if after some additional listening you notice things are a tad bright, you might dial down the tweeter 1-2db or so.

[sdl2112]

I was lucky I bought my C173 mids before the price of neo magnets went sky high. I got them for about $600 each, now they are back over $900 each. I thought 600 was high...

For response tilt or voicing I plan on experimenting with the voicing circuit Jon and others have suggested. I do think that a downward tilt will sound better but I wanted to start with a flat response. The information on this can be found in
this thread.

Here's another graph of left (red) and right (green) with a 5ms gate, 1/6 oct smoothing at the listening position to show the average response and how the L/R compare. The dissimilarity at the high end may be attributed to toe in differences that may not have exactly the same. Btw, the previous graphs were with a 250ms gate and 1/3 oct smoothing.

[Hdale85]

Yeah they are expensive now days. Your design is right around 4 grand for drivers now I bet they are fantastic though.

[sdl2112]

Well, I have the response reasonable flat except for the room influence. I haven't addressed that yet. After more listening it is apparent all the sound is there, just not really in the proportions I like. I always planned for a flat response of the base speaker then shape it with passive shelving circuits ahead of the power amp. Parts came in and I dusted off my breadboard. Initially I tried the 3.2db shelving circuit and it's definitely a step in the right direction. Not dull at all, kind off takes the edge off. It does encourage you to turn it up a little.

I also thought the low end could use a little boost so I'm trying an additional shelving in the low end. These shelving RC circuits are pretty independent but do take away from the overall gain but so far that hasn't been an issue.

I've normalize the gain of the two circuits below for comparison.

Here is the breadboard circuit.


The simulated responses; red is the 3.2db single shelf, the green has the high and low shelves. They track quite well with the green just adding (subtracting less) a little low end boost.


Next is the measured response at the listening position, 250ms, 1/3 oct. A little hard to see with all the room influence but the red is no shelf, green is high shelf only, the blue has the high an low shelves, again normalized to each other for comparison.

[Juhazi]

Excellent speakers! Congrats.
On-axis straight response sounds different with speakers that have different directivity "profiles". With a quite large waveguide like sdl uses, 15¤ off-axis (no toe-in) gives easily 2dB tilt above 2kHz. Also total power response in treble is lower than with a regular dome on flat baffle. Bass level changes a lot when speaker's distance to walls is changed. RTA measurement by moving the mic around the listening spot mathes very well to how it sounds.

I have noticed that decay time (RT) is longest around 2kHz in most rooms that have large windows. Then we need rather high level from the tweeter to compensate, or the sound gets hard and cold.

Tone controls in preamp or in-line are nice and easy fix to adjust sound in the room. It may lead to high distortion with small 2-way speakers. If one has listened only to 2way stand speakers, it will take some time to get adjusted to a floorstanding 3-way sound. Different floor reflection nulling and bass extension make most of the difference.

[ergo]

I plan to experiment with the in line filter also on the WC Ardents once I get the xover settled.... As the WC Ardents are run through NAD C390DD at moment I do need to first move back to more traditional DAC/pre + power amp though. This full digital beast has no line level to stick the filter to

[Dave Bullet]

Can you pin point any particular music / tracks that you want to tame the upper mid / treble on? I've been reading about a 2.5KHz notch and will try that - as I suspect that is where my ears are overly sensitive and playing the tweeter alone with its circuit is confirming something not pleasant is going on there.. .only on certain recordings though.

[Juhazi]

Dave, your speaker has higher directivity between 2.5 - 6kHz. Perhaps you should try how a 2-3dB Q=1 notch around 1kHz sounds? Easiest way to test it is to use some eq plugin with Foobar or other player software. When you get nice balance, copy that in your passive in-line filter!

Speaker positioning and reflection damping/diffusing will also change balance a little, reverberant soundfield is quite important and measurement systems/graphics might look a bit funny when your ears tell it sounds right! Trust your ears! When the loudspeaker has basically good crossovers, low distortion and it goes low enough, it is best to play with (in-line) eq to suit your taste. When you move speakers, listening chair of change furniture, it is easy to adjust eq again. This is one reason why I like dsp-xo so much!

[sdl2112]

I can't say I am hearing issues in that range. That said this is the first time I've had speakers in this room and everything is new. I will say I am really impressed with the Be tweeter and ceramic mid. No metal or break up sounds that I can detect, very articulate, smooth and clean. My biggest issue is getting smooth bass. A lot depends on the recording. Some I say I don't know how it could sound better, others not so much. Listened to Humble Pie - I walk on Gilded Splinters and it sounded a little sterile...what do expect live, yet still sounded pretty good.

[Dave Bullet]

Could that in room mode / peak @ 550Hz be the issue with the bass? I mean, a peak or trough elsewhere can mask or make other areas seem deficient when they may be fine. That measures out to ~ 61cm wavelength. What could that be from? (assuming it is mainly midrange output contributing at that frequency?)