Pythagoras Subwoofer build thread

[billy p]

Ah...I recall you talking about this AE build awhile back....it really turned out beautifully. I'll agree the av12x are no ordinary drivers.... Very efficent drivers for most ported or PR design sub using limited power.
Hehe..not that I'm suffering from buyers remorse but maybe I shoulda gone with a PR's design in the end...oh well.

 

[annunaki]

Ah...I recall you talking about this AE build awhile back....it really turned out beautifully. I'll agree the av12x are no ordinary drivers.... Very efficent drivers for most ported or PR design sub using limited power.
Hehe..not that I'm suffering from buyers remorse but maybe I shoulda gone with a PR's design in the end...oh well.

If you have the driver you can always add them in a new enclosure...

 

[saabracer23]

Ah...I recall you talking about this AE build awhile back....it really turned out beautifully. I'll agree the av12x are no ordinary drivers.... Very efficent drivers for most ported or PR design sub using limited power.
Hehe..not that I'm suffering from buyers remorse but maybe I shoulda gone with a PR's design in the end...oh well.

I have a pair if av15hs and was going to port them to save a bit of money on buying passives. Do you think there is much oh a difference between going ported and going passive? Other than cost and possible port noise?

Dan

 

[billy p]

I have a pair if av15hs and was going to port them to save a bit of money on buying passives. Do you think there is much oh a difference between going ported and going passive? Other than cost and possible port noise?

Dan

Not sure I'm the right person to ask but from my understanding the H series are better suited for smaller enclosures so PR's is the way to go. The AvX .. are better suited towards ported designs and will likely dig deeper...from what I've being able to discern...

Just my 2 cents.

 

[annunaki]

I have a pair if av15hs and was going to port them to save a bit of money on buying passives. Do you think there is much oh a difference between going ported and going passive? Other than cost and possible port noise?

Dan

The AV-15H models well with two of the 18PR-1600s in 6.18ft^3. This has also been confirmed with John since I was upgraded with half of my order to an AV-15H and dual 18PR-1600. That is an upcoming build for one of my brothers

Going vented will end up at about the same size but then you have the vent displacement to deal with. Doing a proper size vent with a woofer like this to avoid vent noise can yield an additional 1.0-1.5ft^3 displacement or more.

 

[pjoseph]

Wow great work! love the paint job

 

[Alex2507]

Filler applied to screw holes and end grain:

All of the sudden I am curious about the filler you used.

You mentioned that you used automotive paint. I take it that goes for the primer as well? I saw the question about dry times but didn't see an answer. Let me ask about dry times in between coats of primer and the dry time of the last coat of primer to when you can wet sand and then how long again before paint?

Can automotive paint be shot out of an HVLP?

Suddenly I have developed a keen interest in the specifics.

How much is a quart of automotive primer? I take it that allows you to wet sand without fear of swelling the MDF?

I saw this thread before of course but now I can relate to it ever so much better. I see you use MDF for everything, even braces. Is that a good enough meets cost effective type of situation and you just live with the weight or is there some sort of magic in MDF?

Way back I looked up the prices of the parts and think with the amp, driver and PR's you might be just under a grand ... maybe $800. I'm really curious about how many man hours that sub might have in it and what the cost to the customer is but understand if want to keep your pricing private.

I also really appreciate the bracing and framework/bracing that the front baffle attaches to ... and where did you put the Bash Amp? If you have this build on video, I want a copy.

 

[TLS Guy]

All of the sudden I am curious about the filler you used.

You mentioned that you used automotive paint. I take it that goes for the primer as well? I saw the question about dry times but didn't see an answer. Let me ask about dry times in between coats of primer and the dry time of the last coat of primer to when you can wet sand and then how long again before paint?

Can automotive paint be shot out of an HVLP?

Suddenly I have developed a keen interest in the specifics.

How much is a quart of automotive primer? I take it that allows you to wet sand without fear of swelling the MDF?

I saw this thread before of course but now I can relate to it ever so much better. I see you use MDF for everything, even braces. Is that a good enough meets cost effective type of situation and you just live with the weight or is there some sort of magic in MDF?

Way back I looked up the prices of the parts and think with the amp, driver and PR's you might be just under a grand ... maybe $800. I'm really curious about how many man hours that sub might have in it and what the cost to the customer is but understand if want to keep your pricing private.

I also really appreciate the bracing and framework/bracing that the front baffle attaches to ... and where did you put the Bash Amp? If you have this build on video, I want a copy.

I always use auto paint for a project like yours, but for cars mainly. I use an HVLP unit.

Surface preparation and avoidance of water, grease and dust are key.

You get a good smooth surface. Wipe with Prep All and then lint free cloth.

Shoot the primer, 20 minutes later shoot the top coat and shoot every 20 min until you have the desired result. Three or four coats is usually plenty. No sanding required unless you go over 40 min between coats, which you want to avoid.

I have a good air tank. I have an oiled line and a non oiled line coming from the ceiling. Obviously the non oiled line is used fro painting and the oiled line for air tools.

I use a top end Dixon water filter well away from the tanks to give the air time to cool.

For good measure I use an inline filter at the sprayer connection also.

Yes, automotive paint is expensive, plus the thinners and hardeners.

I think MDF is best, because it dampens better then hard woods. The glue never completely sets, so there is a residual degree of sponginess to it. It is not perfect, but I believe it is the best material for loudspeaker construction available at present, and I have used it for years. If you spray paint MDF you need to cover it with a thin smooth layer of fiber glass filler. MDF is too rough to spray paint straight. I really, really avoid painting MDF.

I hope this helps.

 

[jinjuku]

Can automotive paint be shot out of an HVLP?

Yes

How much is a quart of automotive primer? I take it that allows you to wet sand without fear of swelling the MDF?

~$20 give or take dependent on paint. You should always seal the cut/exposed edge of mdf. 50/50 Tightbond to water and a few coats (2-3).

I saw this thread before of course but now I can relate to it ever so much better. I see you use MDF for everything, even braces. Is that a good enough meets cost effective type of situation and you just live with the weight or is there some sort of magic in MDF?

MDF is inexpensive. Void free cabinet ply is not. Braces are preferable in ply but not necessary.

 

[annunaki]

All of the sudden I am curious about the filler you used.

You mentioned that you used automotive paint. I take it that goes for the primer as well? I saw the question about dry times but didn't see an answer. Let me ask about dry times in between coats of primer and the dry time of the last coat of primer to when you can wet sand and then how long again before paint?

Can automotive paint be shot out of an HVLP?

Suddenly I have developed a keen interest in the specifics.

How much is a quart of automotive primer? I take it that allows you to wet sand without fear of swelling the MDF?

I saw this thread before of course but now I can relate to it ever so much better. I see you use MDF for everything, even braces. Is that a good enough meets cost effective type of situation and you just live with the weight or is there some sort of magic in MDF?

Way back I looked up the prices of the parts and think with the amp, driver and PR's you might be just under a grand ... maybe $800. I'm really curious about how many man hours that sub might have in it and what the cost to the customer is but understand if want to keep your pricing private.

I also really appreciate the bracing and framework/bracing that the front baffle attaches to ... and where did you put the Bash Amp? If you have this build on video, I want a copy.

Hi Alex,

Let me check with my brother as to what type of spray gun he uses as well as some other specifics. We did put the primer on thicker so as to not reach the MDF while wet sanding.

As for body filler, I used rage gold. I will NEVER use bondo again. This stuff sands and fills so much better it is not even funny.

MDF: I use it to keep costs low. The fact that other than saving weight, expensive plywood (void free high count ply) does not gain anything in terms of measurable performance that I have seen when both enclosures are equally braced.

Time: I have a fair amount of time in this specific project. Probably about 8-10 hours combined in the enclosure construction. I then have about 3-4 hours in finishing labor.
EDIT: As part of the finishing labor I seal the MDF with a shellac made of approximately 60% wood glue 40% water. After it dries I do a light sand with 220. Then another application of shellac, then another light sanding. Then it is ready for primer. This is especially important on end grain.

I did not do any video documentation of this build only photos. The amplifier is externally mounted so as not to sacrifice any enclosure integrity or allow for any air leakage.

 

[Rickster71]

I don't know how I missed this thread.
Very nice! At first I thought it was going to be a marble look for the finish.

 

[annunaki]

My customer has now informed me that he will be selling this most impressive subwoofer. He is building a new home and we will be doing 4 in-wall subwoofers in a dedicated theater area. He was only able to use it (quite sparingly) for about 2-1/2 months before he sold his home. He asked that I begin to get the word out that this will be for sale. Please PM me if there is any serious interest. I will probably be listing this in the classifieds for him shortly.