First Build 2x Jack 112 pics and questions UPDATE: Titan 39

[Sebastjan Pope]

Hi,

I bought plans for Jack 112 more than 2 years ago. I am not sure how I found Bill s website, but right away I was interested and was hooked on idea of building my own speakers that I could use for some small parties or something...

This year I finally made the step and actually start doing it. I bought some plywood, tools( Makita circular saw with Guide Rail, jig saw...) I made myself some sawhorses and Jigs from Bill plans.

I bought drivers and other stuff from Thomman.de :
Woffer driver: 2x Eminence Beta-12A-2
Piezzo drivers: 17x Monacor MPT 016
Power AMP: the t.amp E-800
SpeakON connectors: 4x Neutrik NL4 MPR
Paint: Warnex Structure Paint Black 1Kg
and some other stuff...

In OBI store i got Bison glue PU MAX® Wood Adhesive and it is the right stuff for the job.

I also bought Crossover components from some local seller in my country(Slovenia). He said that the values are not exactly the same but it should not make any big/bad difference:
Air Core Coil 0,680mH +/-3% 0,330Ω wire 1,20mm=17AWG
Air Core Coil 0,430mH +/-3% 0,385Ω wire 1,00mm=18AWG
Jantzen Standard Z-Cap 5,60μF 400VDC 5% MKP dia-21 / 31m
Jantzen Cross Cap 15,00μF 400VDC 5% MKP dia-29 / 44mm.
Resistor Mox 33,00Ω 10W 5% dim.8,5/53 flameproof
Resistor Mox 3,90Ω 5W 5% dim.8,5/24 flameproof
-------------------------------------------------------------------------------

Then the fun started

I first cut all plywood parts for both Jack 112 according to cut list in plans. With aluminium guide rail for circular saw I was quite accurate for inexperience woodworker.
I was actually cutting 2 plywood at one time where I could, so in one cut I got pieces for both speakers.

When I had all parts prepared i started with assembly. I was using Torx screws 3,5mmX30mm and 3mmX20mm and PU glue.

[Sebastjan Pope]

Then i got to flat piezzos array assembley and had a bit of problems and I asked for help in this thread: viewtopic.php?f=25&t=25059
I managed to cut piezzos as needed and glued them with PVC Cement in 8 piece array that fit in a speaker cabinet.

I rounded the corners and sanded cabinets with orbital sander. I also put auto-body kit where it was needed.
I bought some door and window self adhesive foam/tape that I put between the piezzos and wood where they are attached. I used the same foam on the back to make the cabinet airtight.
I was worried that my drivers will not fit airtight because I cut a little to big hole in the driver spacer.
For grille I bought some perforated aluminium. I wasnt sure how to install it on the cabinets. I put painting tape on where I planed to cut them and used an angle grinder. It turned out OK.

I have a friend that went to Electrician School and he did all the soldering of crossovers...

Because I was planing to make a premier test of my new speakers on my birthday party I had to hurry up with the build. The last day I was working until 2:30 am
I must admit that I made a really quick air leak test before I closed the cabinets. I didnt found any leaks.


That day I had the birthday party and I didnt have any Equalizer and the 2x Jack 112 didnt sound too good. We end up connecting some good Hi-Fi speakers that saved the night

[Sebastjan Pope]

I didnt give up on my JACKs. I bought Behringer DEQ2496. I read the tutorial: http://www.decdun.me.uk/deq2496.html
and played some music and EQ.

Now they sound GOOD . I have them on stands and they give full sound with enough low end and clean highs. If I want more bass I put one Jack on the floor.
Its like night and day compered when I didnt EQ them.

[Sebastjan Pope]

OK even if they sound really good to my ears I made some mistakes I know and mybe some I dont know.
So I have couple of questions about my build if someone can help and clear some things out for me

1. Do you think that Hi and Low Filter components I put in are really OK?
I also keep reading about polarity checks when you connect drivers and tweeters.
How it is possible to connect them wrong when It writes on them where is + and - ?


2. For damping I used normal opencell foam 30mm thickness from hardware store. I put the foam right behind the driver, is this OK?
Should I put it somewhere more?

3. I am still worried that the hole in the driver spacer is too big and it will start to leak air at drivers gasket.
I also made a mistake and didnt use Spring Lock washers when attaching the driver to the spacer. Should I repair this?

4. If you look at Auto EQ result you can see some +15db peaks. Is this a sign of some problems/mistakes in my build?
How to properly make Auto EQ outside and inside?

5. I bought the Titan 39 plans. Can I use my amp (the t.amp E-800 stereo amplifier - output power: 2x 500W into 4 Ohms, 2x 350W into 8 ohms)
to run 2x Jack 112 and also Titan 39 together?

[Chris_Allen]

Hi, that's a lot of information to take in at once! Your build quality looks very good considering your self confessed inexperience.

Before going into your questions did you break in your drivers? Also, did you check for leaks round the hats? They can be tricky on the jacks.

The auto EQ doesn't look weird if you did it inside, the room will account for most of that response but you should not need that much correction.

When you have a polarity problem, it will appear as a dip around the crossover frequency, which you don't appear to have. When I used to autoeq my cabs, I would stack them as this naturally flattens response and I got a better reference curve.

Btw, Welcome to the forum.

[Grant Bunter]

Hi.
Nice first build

Is the beta 12 listed in your plans as a suitable driver?
It's not listed in my old J12 plans.

What size phase plug did you use?

OK even if they sound really good to my ears I made some mistakes I know and mybe some I dont know.
So I have couple of questions about my build if someone can help and clear some things out for me

1. Do you think that Hi and Low Filter components I put in are really OK?

They look to be near enough

I also keep reading about polarity checks when you connect drivers and tweeters.
How it is possible to connect them wrong when It writes on them where is + and - ?

Because the + and - connectors may have been made incorrectly in the factory.
Always best to test as per the plans


2. For damping I used normal opencell foam 30mm thickness from hardware store. I put the foam right behind the driver, is this OK?

No. Remove it from behind the driver, or the driver can't adequately cool

Should I put it somewhere more?

Yes. Other than behind the driver, anywhere you can see plywood

3. I am still worried that the hole in the driver spacer is too big and it will start to leak air at drivers gasket.
I also made a mistake and didnt use Spring Lock washers when attaching the driver to the spacer. Should I repair this?

4. If you look at Auto EQ result you can see some +15db peaks. Is this a sign of some problems/mistakes in my build?
How to properly make Auto EQ outside and inside?

Did you use the "target" in the tutorial?
If yes, that is a mistake. You need to set your target based on the SPL charts for the J12, and you will get different results.
If you need help with this, please let us know

You shouldn't try to EQ inside. Your J12's are not hi fi speakers.
Do your auto EQ outdoors only, with at least 17m of clear space to the nearest obstacle (eg house shed etc)

5. I bought the Titan 39 plans. Can I use my amp (the t.amp E-800 stereo amplifier - output power: 2x 500W into 4 Ohms, 2x 350W into 8 ohms)
to run 2x Jack 112 and also Titan 39 together?

Will that amp run both? Yes, but only in mono for the tops.
You will also need to add the DCX2496 to run subs and tops.
Given the power you have in your amp, I would use the BP102 driver in the T39's, and build 20" wide cabs.

[Sebastjan Pope]

Before going into your questions did you break in your drivers? Also, did you check for leaks round the hats? They can be tricky on the jacks.

I didnt brake in the drivers and I check for leaks really quickly I did use a lot of PU glue around the hats, I think there shouldnt be leaks...But I am worried around the driver where I didnt use this "Lock washers" and the hole in spacer was a bit to big...

The auto EQ doesn't look weird if you did it inside, the room will account for most of that response but you should not need that much correction.

In picture attached there is AutoEQ from outside, let say that cabinet was couple of meters from the car and 7 meters from house(left side from speaker) and Microphone was 8 meters from speaker.
There are couple of + 15db spikers an that bothers me. I did AEQ from 80Hz and UP in this picture. It didnt have enough low end and it didnt sound good inside. I didnt try any music outside just pink noise.

[Bruce Weldy]

What kind of mic did you use? It should be an omni reference mic - not a vocal mic.

Like this....

https://www.guitarcenter.com/dbx/RTA-M- ... Rack-PA.gc

[Bill Fitzmaurice]

You're not going to get a lot of bottom outdoors because there's no boundary reinforcement. 15dB of boost or cut is too much. Where the program wants to apply that much back it off to 10dB, which is as much boost or cut that you should be using.

[Sebastjan Pope]

Is the beta 12 listed in your plans as a suitable driver?

Yes it is.

Yes. Other than behind the driver, anywhere you can see plywood

Is the 30mm thickness of the foam too much?

Did you use the "target" in the tutorial?
If yes, that is a mistake. You need to set your target based on the SPL charts for the J12, and you will get different results.
If you need help with this, please let us know

YES I used the "target" from tuturial and one time I used just flat target without any GAINS.
YES I would really need help here!

You shouldn't try to EQ inside. Your J12's are not hi fi speakers.

I tought that first you make AutoEQ outside and than use this result as "target base" and do from this Auto EQ inside?

Will that amp run both? Yes, but only in mono for the tops.
You will also need to add the DCX2496 to run subs and tops.
Given the power you have in your amp, I would use the BP102 driver in the T39's, and build 20" wide cabs.

If I put 2x 250RMS 4ohms speakers on one channel it becomes 8ohms => My amp is 2x 350RMS at 8ohms do this speakes still take 250RMS at 8ohms or they change values?
What happens with second channel on amp in this case? It becomes 8ohms or it stays 4ohms if I connect just one 4ohm driver?

Thanks for all answers and input!

[Sebastjan Pope]

I am using Superlux ECM999 Measurement Microphone - condenser (15-48V), 20Hz-20kHz

You're not going to get a lot of bottom outdoors because there's no boundary reinforcement. 15dB of boost or cut is too much. Where the program wants to apply that much back it off to 10dB, which is as much boost or cut that you should be using.

OK. But should I boost(Include in AutoEQ) Low frequencies from 40Hz to 80Hz?
Is +15dB and - 15dB normal thing?

[Bill Fitzmaurice]

You should not boost 40-80Hz. That's where power and excursion demands are highest, especially as the cab sensitivity drops below 80Hz. That's not an issue with electric bass, since with typical cab placement on stage you're getting 1/4 space loading. It's not an issue with PA when elevated, so long as you're not putting a lot of low end content through it. In PA applications where you need more lows than they can deliver use subs.

[Grant Bunter]

Yes. Other than behind the driver, anywhere you can see plywood

Is the 30mm thickness of the foam too much?

25mm is enough.

Did you use the "target" in the tutorial?
If yes, that is a mistake. You need to set your target based on the SPL charts for the J12, and you will get different results.
If you need help with this, please let us know

YES I used the "target" from tuturial and one time I used just flat target without any GAINS.
YES I would really need help here!

I will answer this one separately

Will that amp run both? Yes, but only in mono for the tops.
You will also need to add the DCX2496 to run subs and tops.
Given the power you have in your amp, I would use the BP102 driver in the T39's, and build 20" wide cabs.

If I put 2x 250RMS 4ohms speakers on one channel it becomes 8ohms => My amp is 2x 350RMS at 8ohms do this speakes still take 250RMS at 8ohms or they change values?
What happens with second channel on amp in this case? It becomes 8ohms or it stays 4ohms if I connect just one 4ohm driver?

Where do you get 4 ohms from?
The beta 12a is an 8 ohm nominal driver, the J12 has 8 ohm filters. Each of your cabs are 8 ohms cabs, not 4 ohm.
2 x 8 ohm J12 cabs "daisy chained", or, in parallel, will present a 4 ohm load to your amplifier on one channel.

The other amplifier channel doesn't care what load is attached to it, as long as it's more than 4 ohms.
The BP102 driver I recommended for your T39 is an 8 ohm driver, so it would be an 8 ohm load on your amplifier

[Grant Bunter]

Target curve.
The easiest way to get a target curve is something called mirror imaging.

Use this SPL chart. The first one at the top of this page:
viewtopic.php?f=12&t=8778

Copy it, paste it into word, print it out.
Get a pencil and draw a ruler line across the chart at 97.5dB.

Set all frequencies on your DEQ to 0.
Whatever is above your pencil line in the J12 response on your printed chart needs to be reduced on the DEQ.

I'll give you some examples:
40,50,60,70,80,90,100Hz, no change.
125hz, change from 0 to -2.5dB
250Hz, change from 0 to -5dB
300Hz to - 7.5db
400Hz to -7dB
500Hz to -7dB

and so on, right across the chart to until you've covered all the frequencies.
You will notice the largest reduction will be around 10KHz, reduce by -10dB there.
When you're done, it should look like the reverse of the J12 chart on your DEQ screen.
For 20 and 30 Hz, set them both to minus 15dB.
For 20KHz, you can probably go -15dB there as well.

You've now set a proper target curve for your cab(s).

Auto eq outside now, with at least 17 metres of space around the cabs.

Once you have done that, save it.
Get back to us...

[Sebastjan Pope]

Auto eq outside now, with at least 17 metres of space around the cabs.

Once you have done that, save it.
Get back to us...

I have made "target curve" using mirror imaging. I have made AEQ from 100Hz to 16000Hz. Then I have manualy reduced the -15dB peaks to -10dB peaks.
I tried and played some recorded Youtube music and the Jacks 112 sound very good to my ear, but I will probably build one Titan39 to go with them because I miss a bit low end(they are on stands).

What do you think about this values? Are they OK?