First Build - A Single JBL 804 16" AutoTuba

[njolliffe]

Hi guys,

So I was randomly trolling youtube and after a few videos came across this :-

http://www.youtube.com/watch?v=WE6BOd3bCWk

Well after seeing and hearing the sound coming from this 'horn loaded sub' I was like and then instantly thought to myself I need one of these.
So a week later I had ordered the plans, bought the speaker, bought some wood and have now started work on the cab.

I am making this sub at work and so I only have a few photos so far. I am hoping to take more as the build goes on.

Back shot of JBL and speaker wire with connector block I plan to use

Front shot of JBl

I was a bit annoyed as I found the jigsaw blade tears at the ply causing these chunks to be ripped off.
I found it helps if you score the wood with a knife before cutting.

Bit annoyed with the tear. Obv it wont be seen on this pan but it happened elsewhere too.

Here are a couple of shots of the panels arranged in place. I haven't started to glue them in yet.

That is as far as I have got atm, I am waiting on some t-nuts which I hope will arrive tomorrow and then I can start gluing.

Talking of glue, I live in the UK so PL is expensive/unavailable. I've decided to use lumber jack 5 Minute Polyurethane Wood Adhesive which is about £7 quid from toolstation.
http://www.toolstation.com/shop/Adhesiv ... 198/p78519
I was wondering if anyone has had any experience with this? I think I chose it as someone recommended it on another thread and it seems similar to PL.

I also have a couple of questions which i'm not sure if I should ask here or start another topic? Figure I'll ask anyways.

1) I am currently using an alpine CDE-9850Ri head unit with an old jet sound js 6085 amp. My current setup uses the 2x150w channels bridged, I am planning on using just one 150w channel for the AT.
The amp has a LPF setting but I've no idea to what freq. this is filtering at. I can't see and don't think this is adjustable. I also don't know the frequency range the head unit is sending out the signal to the sub. Am i right in thinking the head unit will only send the lower frequency range rather than the whole audio range?
I've read that the AT should only play frequencies around 30-120hz ish. My question is will playing music with a LPF which may be set as high as 2-300hz with no HPF damage the sub? (Assuming you don't go over the 28v limit)

2) I have also been considering getting a cheap little lepai 2.1 amp for burning in the sub. 2x40w for the mains and 1x68w for the sub.
http://www.amazon.co.uk/Lepai-LP-168HA- ... 577&sr=8-3
I was wondering if these are any good/anyone has had any experience with it? If not does anyone have any other suggestions for a cheap little amp/way of burning the sub in?

[bassmonster]

Hi guys,

So I was randomly trolling youtube and after a few videos came across this :-

http://www.youtube.com/watch?v=WE6BOd3bCWk

That's the video of "Radian", who is a member here.

BTW, Radian, our very own TimpBizkit commented on your video eight times in a row.

OP, very clean build! As for the wood chipping and splintering with the jigsaw blade, I fill that with wood filler and sand it down flat after the filler dries, and repeat until the surface is flat again. As for the glue, if it doesn't expand you run the risk of leaks. The extra expense of PL or another expanding adhesive is worth paying to save your driver, IMO.

[CoronaOperator]

Your build looks good so far, when you do finish it don't forget to add the braces. I'll try an answer some of your questions:

1) I am currently using an alpine CDE-9850Ri head unit with an old jet sound js 6085 amp. My current setup uses the 2x150w channels bridged, I am planning on using just one 150w channel for the AT.
The amp has a LPF setting but I've no idea to what freq. this is filtering at. I can't see and don't think this is adjustable. I also don't know the frequency range the head unit is sending out the signal to the sub. Am i right in thinking the head unit will only send the lower frequency range rather than the whole audio range?
I've read that the AT should only play frequencies around 30-120hz ish. My question is will playing music with a LPF which may be set as high as 2-300hz with no HPF damage the sub? (Assuming you don't go over the 28v limit)

Your particular head unit sends the full audio range to the rca outputs. I couldn't find any info on your amplifier but I'm going to assume that the x-over is factory preset to between 80-120 hz. Pre-set x-overs were quite common back in the day and 80-120hz is usually where they were located with a 12dB/octave slope. Playing frequencies higher than designed for will not hurt the sub as long as you don't go past the voltage limit for the driver.

2) I have also been considering getting a cheap little lepai 2.1 amp for burning in the sub. 2x40w for the mains and 1x68w for the sub.
http://www.amazon.co.uk/Lepai-LP-168HA- ... 577&sr=8-3
I was wondering if these are any good/anyone has had any experience with it? If not does anyone have any other suggestions for a cheap little amp/way of burning the sub in?

Those little amplifiers are great for what they are but don't believe the wattage rating on then. They put out about 18 w /channel at the most. I suppose if it was hit by lightning it is possible to register 2x40w for a brief moment, hard to say.

[Ryan A]

Nice looking build so far.

I would keep the amp you have now. Is it 2 X 150 @ 2 ohms per channel? If so, you could even bridge the amp to your AT, seeing as how the AT will be around a 6-8 ohm load. If its rated 4 ohms per channel then maybe stick with the one channel to the AT.

[Truckinve]

That PU gel seems to be okay, did a research long time ago on Everbuild, and the catalog is so huge.

Cheers

[Chris_Allen]

PU works fine but I would steer clear of the 5 minute stuff, it is very unforgiving. I've used that particular PU and it goes off very quick. When you are preparing clamps, using screws, positioning carefully, 5 minutes is not much time to get it right! and when you have to clean down a failed attempt at positioning a panel, it is very annoying.

http://www.tradingdepot.co.uk/DEF/product/!!30MINPU3!!/
http://www.amazon.co.uk/Everbuild-30MIN ... 635&sr=8-4

I get mine locally from a lumber yard.

30 minute products tend to be stronger too.

[Bill Fitzmaurice]

Talking of glue, I live in the UK so PL is expensive/unavailable. I've decided to use lumber jack 5 Minute Polyurethane Wood Adhesive which is about £7 quid from toolstation.

http://billfitzmaurice.info/forum/viewt ... 14&t=17239

Effing up a build for the sake of a few quid is not a wise decision.

[Truckinve]

Wooops I think it was the 30min

Sorry

[njolliffe]

Thanks for all the replies.

Effing up a build for the sake of a few quid is not a wise decision.

Hi Bill, thanks for chipping in. I had seen that thread whilst looking for PL sources in the UK, the amazon link is no longer available and the cheapest place I could find is about £21 ~ $33 delivered for one tube on eBay.
I couldn't really justify spending this much on a tube of glue.... esp when the 4x8 sheet of BB birch already cost me £48 ~ $75

when you have to clean down a failed attempt at positioning a panel, it is very annoying.

Haha Chris this is too true, although not really a failed attempt but you'll see why in the pictures below. I think next time I will definitely get the longer cure time version (not that i't would've helped in the example below but I can see it may be a problem in the future).

Is it 2 X 150 @ 2 ohms per channel?

I am having a hard time tracking down the specs of this amp. It was my dads old unit and is at least 10 years old so there is very little info on the net. I've had a quick look round the amp but can't see anything about what ohm rating the output is. I am going to pull it out the car at some point and have a look to see if there is some more info on the bottom. I did see a 'level' dial though which at first I thought may be a gain dial but now I'm thinking it may be something to do with the X-over, especially as it also has a HPF setting.

Those little amplifiers are great for what they are but don't believe the wattage rating on then.

I'm still undecided on these, will probably leave it for now as my flatmate has an HT amp and failing that I will just use the amp in the car for breaking the sub in.

As for the glue, if it doesn't expand you run the risk of leaks.

I had some doubts about this glue but now after fitting the first panel I'm almost 100% sure it will be fine for the job.


Anyways, on with the build. Unfortunately the T-nuts didn't arrive today, they should be here tomorrow. As they didn't arrive there wasn't really much to do apart from fit panel 1. Lol I spent a while trying to get it perfect as I read a miss aligned panel 1 can throw out the whole build, however it didn't turn out quite as planned.

I used the right angle jig method to screw the panel in place. Gotta remember to fill in the holes.

Bead of the Lumber Jack PU. Nice and neat...

A bit too much squeeze out.

So after waiting about 10mins, at which point the glue joint should have 'fixed' the panels in place but not yet fully cured, I decided to remove the Jig. Out came the screws, but the Jig wouldn't budge.

Had to smack it pretty hard with a hammer before it finally released. Lol unfortunately it took half my MDF jig and a layer of ply with it...

So the 5 min, time saving, fast curing glue took another 20mins to sand and chisel back down. Was thinking I should properly check the damage and make sure there are no little fingers of loose wood as I guess they could start buzzing around?

Lesson learnt, next time I will chamfer the Jig so the glue has squeeze out room and I will apply a little less.
On the bright side I'm now pretty certain the glue has a strong bond and decent expansion, and I'm not too fussed about the damage to the ply as it wont be seen.

I was a little worried my 'gentle persuasion' may have knocked the panel out of position but its all good.



So yeah, that's all I could do really, just waiting on the T-nuts before fitting the sub to check clearance and fitting panel 2.

[sine143]

I line my right angle jigs with parchment paper, adhered with painters tape. prevents the stick.

[Tom Smit]

It looks like a good start.

About the squeeze out, just leave it where it's not in the way. Only the last panels may need some trimming.

[Chris_Allen]

Yeah, I never clean on the inside, only the outside panels. Leaving the glue there will just make it stronger and reduce the chance of leaks. What you can't see won't hurt you.

[Ryan A]

Thanks for all the replies.

Is it 2 X 150 @ 2 ohms per channel?

I am having a hard time tracking down the specs of this amp. It was my dads old unit and is at least 10 years old so there is very little info on the net. I've had a quick look round the amp but can't see anything about what ohm rating the output is. I am going to pull it out the car at some point and have a look to see if there is some more info on the bottom. I did see a 'level' dial though which at first I thought may be a gain dial but now I'm thinking it may be something to do with the X-over, especially as it also has a HPF setting.

Those little amplifiers are great for what they are but don't believe the wattage rating on then.

I'm still undecided on these, will probably leave it for now as my flatmate has an HT amp and failing that I will just use the amp in the car for breaking the sub in.

Check the voltage output of it when bridged at max output, without speakers hooked up. This voltage probably won't be useable anyway since the distortion level at max voltage is probably quite high, but it will give an idea of its capabilities.

[88h88]

For the record I've used that 5 minute PL before and it works. However it's a complete arse on bigger speakers such as tubas/titans as the panels are bigger and more of a faff to get into place, checked, double checked and then secured. It works but the 30 minute stuff is better for bigger builds purely because you can realise 'oh bollocks that panel's in upside down!' and still rescue it as it doesn't fully harden until 45 minutes to an hour later.

[osse]

For the record I've used that 5 minute PL before and it works. However it's a complete arse on bigger speakers such as tubas/titans as the panels are bigger and more of a faff to get into place, checked, double checked and then secured. It works but the 30 minute stuff is better for bigger builds purely because you can realise 'oh bollocks that panel's in upside down!' and still rescue it as it doesn't fully harden until 45 minutes to an hour later.

Happened me quite some times when building..! good advice

Also, I'm amazed that you chose to build the AT based on that video, as it gives very little justice to the design... the real thing will be much better than what was be caught on that camera!