SI 2+2 HT18 D4 Sealed Build (Revival of old build thread)

[Sonnie]

This is the last sub build I had from 2013. Joe Alexander drove down from Wisconsin and purchased these from me a while back... after one of our speaker evaluation events. As with my other revival build threads, this only has my posts and pictures I am already hosting on my own site. It is missing all the other member posts since it was originally posted at HTS.

I may as well join the SI HT18 build party... as it seems we got about fifty-eleven build projects going on with them right now. I would expect no less at their bargain pricing.

Nothing fancy here... just a pair of 18's in a sealed box (approx. 11ft³ per enclosure).

Graham (gperkins_1973) provided the enclosure and cutout specs for me.

I ended up going with two inner baffles and only one outer baffle.

My cabinet guy had a stack of ¾" MDF in his shop... $195 got me the MDF and the large cuts on his table saw, so all that I had to do was cutout the bracing and driver baffles, which took me a couple of hours.

Three of the four SI HT18's:

Fourteen clamps:

I hope to get the sides and bottom on tomorrow, then get started on the other one before priming and painting both.

 

[Sonnie]

It is oh so slow going... just got too much going on, but I hope to get the edges routed and some black texture on these sometime tomorrow.

 

[Sonnie]

I had to move the enclosures in to the HT room to finish them. It is absolutely too cold to work in the shop which has no heat. I have the texture finish added and as soon as they warm up to room temp, I will add the first coat of black paint. That will smooth out the texture a little and make 'em look purty. These will be over 200lbs each with the drivers installed.

 

[Sonnie]

They are finished. Not quite the finish I wanted... the texture did not work out as good as it did for me on my other subs, but it is dark in the room and most folks would never know the difference.

I suspect I will probably end up painting the screws with some black direct to metal paint I have.

I already have them split up on each side of the room and they both look the same.

 

[Sonnie]

Swapping out the other subs resulted in about the same corrected response. Naturally the new subs do not need quite at much power to reach the same levels. A small improvement in the extreme lower end, but not anything I will probably ever notice. I did not level match these prior to measuring their response, but have adjusted the offset for a better comparison.

 

[Sonnie]

At that time I had 8 (eight) 18 inch subwoofers in the theater room... the quad 18's in the riser/wall subs and these dual 18's in the front corners... and a little over 10,000 watts of power in the room.

 

[chrapladm]

Nice results. I think spraying is the best option for great finishes. I will be buying a simple Wagner setup soon to do my projects with.

And being only $149 I think everyone should own a pair of SI 18's.

 

[muzz]

I still have (2) of the original D4 HT-18's, 1 I took out of the box to look it over, the other box has never even been opened...one of these days I'll upgrade the power in my room and actually build boxes for them... until then I'll just run my PA460's..I just couldn't resist the $149 mentioned above..I've had these for 2.5-3 years.

 

[Talley]

At that time I had 8 (eight) 18 inch subwoofers in the theater room... the quad 18's in the riser/wall subs and these dual 18's in the front corners... and a little over 10,000 watts of power in the room.

Interesting... and now you have just dual PB-16 Ultras?

 

[Sonnie]

Now I have dual DIY Dayton 18's powered by a couple of EP2500's.

I had to down size a bit due to some financial constraints, so the PB16's had to go, unfortunately, but I am happy with the dual 18's. If I had not had the EP2500's, it would not have worked out quite as well, but they were just sitting around, so figured I may as well put them to work. Here's the thread on those: https://www.avnirvana.com/threads/d...max-sub-kit-um18-22-and-denovo-flatpack.1453/

I need to update it with some finalized pics... been super busy of late with the holidays and opening second location, but things will likely slow down a bit and I can get more active over the next few weeks, and get caught back up here.

 

[Talley]

I'd be very interested in hearing your input on the dual dayton 18s vs those PB-16's. You obviously have had your fair share of sub-woofer experience. I could easily swing 4 of those dayton kits and stack two high on each side of my towers.

 

[Sonnie]

The 16's had more flexibility with tuning with the built-in programming, which I really liked. As far as quality, it's hard for me to compare them, as my ears with low bass like this is not that good. The 18's do the job for me, although critical listeners might not be as happy with them. They play plenty loud, give me all the tactile feel I care for, and they sound good enough for me, although deep down I suspect the 16's are better in many ways.

 

[Talley]

That's probably a fair assessment.

I think I've made up my mind... dual HSU is definately adequate for my 3kcuft room. But if I ever did upgrade I would go straight for dual JTR 4000ULF's. Just no way around it... those are what I would buy.

In fact... I may keep my dual HSU's have them for the mains and then ad a single JTR for just the LFE channel.