Construction journey-Active 3-way

[MJL21193]

Ah well, never mind John. If you'd come back and said it worked, well I'd have been tempted to have a go myself as I have the some problem as you - poor weather this time of year. I'm still waiting to finish up the spray job on the last LGT.

It was worth a try, I guess. I thought you had both of the LGT's finished already, just held up on amps.

I suspect we have this in common: I'm not so much interested in the finished product, but in getting it to the point where I'm satisfied and it looks finished to anyone else. Nothings finished in my book, everything is up for modification or total rebuilding. I get my pleasure from the doing, not the having.

Late last summer I was tempted to build a collapsing paint booth from something like cotton bedsheets and metal conduit. Something I could count on to be dust free and confined enough to heat up a bit with a small electric heater. I'm thinking about doing it now.
I think it would be nice to have anyway, if properly constructed. Painting outdoors still has the odd speck of dust or flying insect lodged in the paint job.

I'll have to make a clandestine raid on the linen closet for likely materials.😀

 

[ShinOBIWAN]

It was worth a try, I guess. I thought you had both of the LGT's finished already, just held up on amps.

They're finished as in they're fully functional and working but one is only partially sprayed up as I ran out of time after winter hit early last year. The amp problem is... still a problem. 🙂

I get my pleasure from the doing, not the having.

I'd say its about 50/50. But I think all DIY'er tend to get bored of what they've built after a period of time or an idea pops up. This is when the next project comes into view.

Late last summer I was tempted to build a collapsing paint booth from something like cotton bedsheets and metal conduit. Something I could count on to be dust free and confined enough to heat up a bit with a small electric heater. I'm thinking about doing it now.
I think it would be nice to have anyway, if properly constructed.

I keep dreaming about stuff like that but its just too impractical for me. I've thought about getting a short term lease on a lockup and doing the spraying in there but its more hassle than its worth by the looks of things.

Painting outdoors still has the odd speck of dust or flying insect lodged in the paint job.

All adds to the charm. I find pointing out the defects are great when trying to prove you've built something. If it wasn't for those some folks would think you were a lying something-or-other.

I'll have to make a clandestine raid on the linen closet for likely materials.😀 [/B]

That reminds me of the time I cut up one of my t-shirts because I couldn't find any clean rags. Everything is up for sacrifice in this hobby. 😀

 

[MJL21193]

They're finished as in they're fully functional and working but one is only partially sprayed up as I ran out of time after winter hit early last year. The amp problem is... still a problem. 🙂

Yes, I had more than enough trouble with my amps also. I have it all working, but I'm still not completely satisfied (I never am 🙂 ). It's tough doing a combined project, where the success of one part depends on the other.

I keep dreaming about stuff like that but its just too impractical for me. I've thought about getting a short term lease on a lockup and doing the spraying in there but its more hassle than its worth by the looks of things.

All adds to the charm. I find pointing out the defects are great when trying to prove you've built something. If it wasn't for those some folks would think you were a lying something-or-other.

That reminds me of the time I cut up one of my t-shirts because I couldn't find any clean rags. Everything is up for sacrifice in this hobby. 😀

In my line of work I wear out clothes all the time, so not uncommon to see old t-shirts as rags (especially the free ones they used to put in the beer case).

I have the space, or I can at least clear enough space in my shop to fold out a decent sized paint booth - maybe 8' x 8'. This would be big enough for most jobs I think. I could make it like a big cube, floodlit from above with the light shining right through the cloth. I am getting excited...🙂

I painted the baffle with two coats of black eggshell spray enamel. Looks presentable anyway.
I'll start on the finish layer for the body next.

 

[Ray Collins]

John,
Sorry about the roller failure; I was hoping for a painting process between spray cans and a compressor/spray gun system. OH WELL.......

Ray

 

[MJL21193]

Box for woofer is 33 litres, tuning freq. 59hz, F3 is 63, Qtc is .628.

Getting back to the original speakers, the above is quoted from my post #39.
More listening and I think I should make these vented. I have ran the calculations through Unibox and I think I'll be more satisfied with the bass response if I add a port.
The unibox sim shows the Fb at 42hz and the F3 at 43hz with a 2.5" x 4.5" port. The best place for one is at the back, below the connection plate.

I think I'll give it a shot. If I don't like it, I can always block it.

 

[F1 FAN]

Hi John,I think you will prefer going the vented route if you don't have a subwoofer to augment the bottom end.Interestingly I used the P21REX in a 28 liter vented box with good results.When I later added a sub I just plugged the port which gave me a sealed box with an f3 in the low 60's which became the xover point to the sub.I recently changed the P21's to the CA21REX's with little change in the f3 but they do sound a bit better.I can't remember the specifics of the port tuning but I will dig them up and post it.

Our systems seem to have a lot of similarities.

 

[MJL21193]

I do have a sub that I use for HT.
My original idea was to supplement these speakers with matching subs. While I still plan on doing that, I'd like a bit more bass right now.
Besides, Unibox shows the driver exceeding xmax with the sealed enclosure below 90hz at 40 watts. Now, that's about 104db for this driver, but that doesn't leave room for transients.

Vented performance looks better for this driver.

 

[MJL21193]

I went ahead and put the vents in. I couldn't find a pipe with a 6.4cm inside diameter, so I used two 2" ABS pipes. These have a 5cm inside diameter. A little more work with Unibox to determine the right length plus I subtracted 1 litre of volume for the vents (these are 17cm long with about 15cm inside the cab - close enough to 1 litre).

I also left the rockwool stuffing inside, I just made sure it wasn't around the mouth of the ports.

 

[MJL21193]

They sound better. The bass goes much deeper. I would say this is a big improvement.
I have never been a big fan of bass reflex, but using an 8" woofer limits the low end. Luckily I selected a driver that is suitable for vented alignment as well as ported.

If the time comes when I build the subs for this pair that I want to change them back to sealed, that's possible. I'd just glue in the correct plug available for this pipe.

Here's how it looks. Nice and tidy, you'd say it was always there. I glued them in in the same way I glued the centre channels port in - cut a groove for the epoxy to help anchor it.

 

[MJL21193]

Massive improvement in the bass response with the change to bass reflex. My prior prejudices against vented speakers are washed away. I've been converted.

I have "finished" the centre, as in got the 1/2" maple veneer plywood on the body and I put in the crossover and driver for a listen. I didn't bother with the styrofoam wedges on this one, as I don't think they are doing an effective job in the mains - I had to add quite a bit of stuffing in the mid chamber. This one I have squares of rockwool behind the driver, between the centre brace and the port tubes.

How does it sound? Very good, a surprising amount of bass for such a small box. Strong in the midrange and the treble is very clear. Tony did a good job designing this crossover.

Getting cluttered with the speakers I have sitting around. Worse things to complain about though. 🙂

 

[PB2]

Paint and stain materials?

Hi John,

Very nice looking cabinets there!
Woodworking came natually to me but I don't often get into fine finishing, your results look highly professional.
I have also done some automotive painting so I know the basics of how to shoot paint.
Would you mind telling us exactly what paint, and stains you're using to get that fantastic look? I might give it a try.

You're also choosing some nice drivers, I used that SEAS woofer in a design over 15 years ago. Looks like there is a cone coating on the newer versions.

Pete B.

 

[MJL21193]

Thanks Pete,
Details on the paint I've settled on start here. It's waterbased urethane paint - industrial floor paint. It is very tough, much tougher than any other 1K paint I've ever used. Polishes beautifully.

The stain:
"The stain is a mixture of three colours, two brands and two types. I have Minwax Sedona red, Minwax Ipswich Pine and Flecto Cherry gel stain. The Minwax is liquid brush on.
This combination is like thin paint, when brushed on it stays on the surface without excess running, and doesn't evaporate quickly. I leave it on for about 15 minutes, then wipe it off with a clean cloth."
Quote taken from my post #63 in this thread.
I do two coats of stain, letting the first dry completely (overnight) before applying the second. The second coat makes it a bit darker and evens out the colour.

For a final finish over the stain, first I use one coat of solvent based clear urethane. I find this highlights the grain and improves the vibrance of the colour. After that drys completely, I sand that smooth and follow with several coats of waterbased clear urethane.

I put the second coat of stain on the new centre speaker today. It'll be ready for the first coat of urethane tomorrow.
Here's how it looks. I sold out and used a plastic terminal cup for this one. I did cut a recess for it to sit flush though.

 

[AKN]

Hi John,

You sure make good looking speakers with great finish.

I'm interested in your opinions about the SEAS coax with series filter by Tony Gee.
For instance, have you got any impressions if it can play loud without strain, particularly in the midrange?

 

[MJL21193]

Hi John,

You sure make good looking speakers with great finish.

I'm interested in your opinions about the SEAS coax with series filter by Tony Gee.
For instance, have you got any impressions if it can play loud without strain, particularly in the midrange?

Thanks 4fun,

Unfortunately, I don't have two of these speakers for a listen in stereo. I don't like to try and judge the speaker quality in mono, it never sounds right, so I paired it with the left side 3-way for a listen (the picture further above, with it on a paint bucket).
It would be unrealistic to expect it to keep up with the 3-way, but it performed very well. Midrange is very clear, highs are well detailed . I think above I compared the tweeters performance to the SS 9300 I used in the 3-ways and I must say it's impressive.
Bass is strong and tight and more than I expected from this small speaker.

As for it's ability to play loud without strain, I can't say for certain yet. I didn't "crank" it up during my first listen, as I was just trying to judge it's quality for a centre speaker. TBH, I don't think it would have any problem at all playing loud, especially in the midrange.

From what I've heard so far, I'm not tempted to change or tweak this filter in any way. When you consider that I used this driver right out of the box without measuring it and matched it to Tony's crossover without testing, that's not a bad result.

 

[ShinOBIWAN]

I don't like to try and judge the speaker quality in mono, it never sounds right,

Mono is the ultimate useless test 😀 And by that rather pointless train of thought, if sounds good in mono you can bet it sounds good in stereo.

 

[MJL21193]

And by that rather pointless train of thought, if sounds good in mono you can bet it sounds good in stereo.

Hi Ant,
Good or bad, it just sounds weird. I will try it right now, speaker is connected to the centre channel on my HTR. I'll switch to 7 channel stereo, disconnect the rear surrounds and turn off the active amp and see how it it is...

Listening now. Speaker has good full sound, nice clean midrange, smooth bass and clear treble.
Sound stage is a little narrow... 😀

Seriously, you're right Ant, I can actually hear this speaker now. Once again, I stand corrected.
A little flexibility in your approach to doing things is an asset in this hobby. 🙂

 

[ShinOBIWAN]

Seriously, you're right Ant, I can actually hear this speaker now. Once again, I stand corrected.
A little flexibility in your approach to doing things is an asset in this hobby. 🙂

🙂

Wish I didn't have to but sometimes I'm forced to live with mono for a number of weeks or even months at a time because I'm left finishing up a second speaker. Its underwhelming at first because there's no imaging, panning or soundstage etc. Its all rather flat and small in direct comparison to stereo. Listen a bit harder though and it offers another way of hearing issues. You don't have any stereo related attributes to impress you. I'm not saying this is the way to tweak a loudspeaker, you listen in stereo so that should be the final arbiter, but its something I've gotten used to doing over the years and yes, its possible to have something that sounds good in mono.

PS. its better that you sum the stereo signals when doing a mono playback so as you hear both the left and right channels. Some recordings can sound weird if you only playback one channel of a stereo recording, particularly if there's pans or steering.

 

[MJL21193]

PS. its better that you sum the stereo signals when doing a mono playback so as you hear both the left and right channels. Some recordings can sound weird if you only playback one channel of a stereo recording, particularly if there's pans or steering.

I always have a pair of speakers hanging around to listen to while I'm finishing the latest, so I've avoided mono.

The centre output from the HTR (in 7 channel sterio mode) is both channels combined, so it's the complete recording.

Closing my eyes and just listening, I'd swear this is a bigger speaker. A capable centre for sure. It has the same clear resolution as the 3-ways - a good fit.

 

[MJL21193]

Talking to Andy Graddon here about the mids used here. I'm considering opening the back of the cabinet, as I believe it will improve the midrange. I need to do some more listening before I take this step.

As for opening the back, here's the plan: cut a hole the nearly covers the rear of the midrange/tweeter chamber. Cut a recess around it to receive a grill frame with ordinary black speaker fabric on it.

Another thought I had was to put a rear firing tweeter in. I have a pair of Pioneer 1" metal domes that I'd be willing to experiment with. I haven't heard a speaker with a rear firing tweeter before, but I've heard good things about the results. Thoughts? Comments?


Here's a quick paste on an existing photo of roughly how it would look. I think I could manage to make it look neater. 🙂

 

[Andy G]

try to get as much opening on the back as you can. maybe consider using a smaller faceplate rear tweeter on a small semicircle of wood eg Vifa D26NC

I think that cavity you have created behind where you have the tweeter on your diagram will cause all sorts of problems !!!