H-Frame Subwoofer & Other HT speakers build

[arunkvivek]

As some of you might know, I have bought a bunch of drivers from US as my parents were returning. Tang band FRs, GRS 15 inch SW and few other goodies. I am also getting Magnat IC62 ceiling speakers for atmos speakers build. I intend to document this thread with the build of these speakers.

The Tang Band FRs have been put on break-in drill. But, I think H-frame sub-woofers are the lowest hanging fruit for me. I have bought 2 pairs GRS 15 PF for H-frame subwoofer for living room HT purposes . I am going to have them powered by Behringer 3000D with 2 SW wired in parallel per side. I am going to use Marantz AVR's LFE for inputs (~ 150 HZ or 120 Hz cut off) and have the LF managed by Behringer to have SW reach 30 Hz without troubling the X-max. I hardly push the AVR volume beyond 10 o clock position. Given this background, I have a couple of questions regarding the H-frame build:

1. I read a thread which mentioned about moving the front baffle by a couple of inches to ensure that the acoustic center of the woofers are in the center of H-frame.
I am looking at 33 in X 16 in X 16 in (H X W X D) build on 18mm MDF with the baffle (double baffle) positioned at 6 inches from the front. I am too much of noob to translate radius driven formula to compute the SW H frame depth. what should be ideal depth of the H frame on front and the back? Any help in this regard is deeply appreciated.

2. Should the woofers be mounted to fire front? or would mounting them in opposite directions (push-pull) reduce performance? Although, I can try both options before finalizing, I want get the driver rebate (chamfering, may be) on the rear of the baffle done by the carpenter. I am thinking push-pull config would add stability to the frame but not aware as to what I would lose. Could you please advise on which of the two options are better?

 

[arunkvivek]

@Hari Iyer , @yogibear, @Naveenbnc - Any inputs?

 

[arunkvivek]

@yogibear, Thanks for the valuable inputs! I am in talks with carpenter on the rebate part (to be done after experimentation). For now, I am looking to have two SW in a single baffle as building separate frames would increase the SW height to 36 inches without isolation..extremely poor WAF.

I shall try both the alignment and see what works. I am still waiting for my amplifier to reach (expected next week).

With regard to Tang Band FR break-in, I am playing Jim Reeves playlist at extremely low volumes for 4-5 hrs and then a couple of hours break for the amp to cool down and then same drill again. A lot of feedback on W5-1611SAF is that the real sound signature shows up after 50 hours mark. I have clocked around 15 hours so far. I would continue the drill until 100 hrs before building the boxes for them.

 

[arunkvivek]

@arunkvivek Yeah, its a good idea to mount both drivers on a single baffle for H frame. You can flip the driver for Push Pull experiment and decide when you listen to both. Cross at 150-100Hz and decide yourself which sounds best. You may cross lower to 70-80Hz in case of push pull but the full range may not be able to catch so low. Since the drivers are large 15" and two of them are mounted on single baffle, try using more than 18mm thickness. Use 24mm or even 36mm. Though its a real pain trying to paste two 18mm thick ply, cut holes and do the finishings. And when you are trying to talk sense into mind of "Indian species of carpenter", then this "pain" doubles up. I am myself struggling with baffles of my new OB build and trying to talk sense into one. Despite all my design musings, my baffles will stand tall to 50" height. Cannot help it.

Breaking in of driver by playing is just fine. But forcing them by feeding some Hz tone is not, IMO. And further, Its much better idea to break them in first and then measure the TSP to simulate your desired cabinet design.

Good luck on your build. Share some pictures as you progress and your sonic impressions.

The carpenter refused double baffling 18 mm... he is too busy to build the box. So, he offered a favor of cutting the speaker mounting holes and I could build the frame myself!!!
So ended up buying 25 MM Greenland Mdf @ 94 per sq ft, got it cut to right size. damn these are heavy. twisted my leg moving the pieces.
Need to drive some pilot holes for putting in screws after glueing since I don't have clamps for the force.
Targeting Christmas for glueing!! Hopefully will get the amp by next weekend

 

[keith_correa]

With regard to Tang Band FR break-in, I am playing Jim Reeves playlist at extremely low volumes for 4-5 hrs and then a couple of hours break for the amp to cool down and then same drill again. A lot of feedback on W5-1611SAF is that the real sound signature shows up after 50 hours mark. I have clocked around 15 hours so far. I would continue the drill until 100 hrs before building the boxes for them.

Burn in

Enjoy the videos and music you love, upload original content and share it all with friends, family and the world on YouTube.

www.youtube.com

 

[arunkvivek]

Updates
probably the last time I would work with MDF. I got a huge pile of dust is from drilling 50 odd holes.
Got schooled for dirtying the clothes drying on the line.
Finished the dry fit of the frames, drilled holes for speaker mounting (for a first timer, it was nightmare).
Mistakes:
1. Missed pilot holes for a few screws and they slowed down the work drastically. Tightening in MDF is far more physically demanding than in a plywood. One more reason to switch to ply.
2 . The baffle cut size - 14" per parts express was slightly oversize. This gave less than ideal thickness for drilling holes with1/4" bit. Luckily the MDF did not give way. There was enough material to drill a bit to sink in t- nuts. Need to learn how to measure a speaker dia for baffle cut!
You would see that one of the t-nut is on foot board with one leg in the air. Thankfully, the speaker tapers an inch away from the cut when mounted. No harm done!!
I also tried Asian paints loctite (araldite kind of product) for one frame and fevicol marine for another. I love the adhesion from Asian paints. Only after trying the marine glue, I realised how good the Asian paints loctite was. I was able to @tcpip's recommendation of araldite to test and wholeheartedly agree with him. Must finish as much as possible this weekend as workload at office is piling.

 

[adas]

Try to get the t-nut flush and put a dab of glue on them carefull not to get it on the threads.. nice build though

 

[arunkvivek]

Try to get the t-nut flush and put a dab of glue on them carefull not to get it on the threads.. nice build though

I am scared of filling the thread with glue and hence just hammered them in for now. If they fail to stick to the baffle, I shall glue them on.
@keith_correa - my dad is monitoring the break-in drill. So he is driving the playlist. Moved from Jim Reeves to Ranjani-Gayathtri for now.
Got some goodies from Germany - Behringer NX3000D, Stagg rca to xlr cables, phono cable for upgrading my TT, a few banana plugs.
Unable to hold the itch, to assemble the connectors, speakons & driver terminals and test the SW or finish the lamination of the SW. No work at the office but will have to go to collect the ceiling speakers tomorrow ;-)
Pic of the day:

 

[arunkvivek]

Made a lot of progress -
1. Mounted the drivers And unmounted them as I did not get the terminals aligned !!
2. Got the wires fixed with crimp terminals so that I can plug and unplug them.
3. Connected speakons with LAN cables for speaker wires.
4. Connected the amp, learnt how to set the crossovers without connecting to a laptop.
5. Tested the amp and it is rock solid. The limit indicator LEDs don't even light up before my listening limits are reached. (Too much boom though as I am yet to re-calibrate AVR and setup right DSP modes).
4. Unmounted the drivers and stuck vinyl self adhesive wrap ( from AliExpress).
5. The fan of Behringer amp was extremely noisy as noted in multiple forums. I wanted to witness it first hand to see if it was bearable. It was not.so, the fan was replaced with low noise fan. Also, fixed additional heatsinks for better cooling.
After powering up, I had a doubt if I wired properly or not as the fan was so quiet.

I shall complete the other SW tomorrow. The family is more or less in agreement with a tentative position for SWs. I might end up disposing of the AV racks and build a new one.

A few pics:

 

[arunkvivek]

The H-frames are done. Fixed the terminals for connecting speakons. As an unplanned purchase, I got LG C9 65 inches for the new year!!!!
Had to put a demo system for my dad to impress upon relatives! I chose an alternative position right behind the recliners for the SW. This position had 5 feet space behind them. Family objected to this position straightaway as it looked very odd close to the pooja room. we started off with Jurassic Park as demo before people arrived. I promised them that it was temporary. I have setup the SW amplifier crossover with 20 hz to 150 hz (LR48 crossover on both the end). Suggestions are welcome in this regard as I am not aware what ideal crossovers should be.

I was supposed to go JC road to buy rubber matting used in Gyms for tightening up the bass (check this thread). I wanted to just have the movie started without any hiccups. while my wife was getting ready, I was watching the movie. I knew that the bass thrills would arrive during the park tour chapter. The film was meandering to the excavation scene when my wife got ready. I asked her to wait for a couple of minutes as Attenborough would arrive by chopper (nice surround effect).

Out of blue, there was a shot when two guys load some sort of gun and shoot it in the air. Boy, this had deep bass. This non-descript scene was never registered in my memory. As I wasn't expecting this moment, it sent chill all over the body. I couldn't stop gleeing for next 10 minutes. Entire family's changed from reluctance to joy. They were now convinced that I could get DIY working. The recliners had tremors. Shopping cancelled and we continued watching the entire movie. Felt like we were in movie theater. Extreme satisfaction even without AVR re-calibration. I was transported back to 90s when I watched the movies in Sathyam theater in Chennai as kid. Five feet behind SW made all the difference between first run and the demo run. I wish i could bribe my way to get this position from the family. I don't think I would ever get this bass from the position that we have finalized for the SWs (just below the AV rack).

With office work taking over my time, I don't think there would be any more updates until end of January. I am waiting to finish off the surrounds/Atmos speaker build and recalibrate everything. Need to figure out a way to get the same performance from 1.5 feet from wall. I have started reading about cardioids. It needs more than an accountant's IQ to achieve the cancellation of bass in a single direction. Anyways no action for now.

I would like to thank @Hari Iyer and other FMs for their detailed conversations on open baffle build. This thread along with @Naveenbnc 's rapid prototyping builds were great inspiration for me to start. Most of all, it was @yogibear endless inputs on driver shortlisting, frame dimensions that made this build possible.

 

[mpw]

Congratulations !

You will find the sweet spot for placement I guess if you sweetly convince your family...

Njoi !

 

[arunkvivek]

Congratulations !

You will find the sweet spot for placement I guess if you sweetly convince your family...

Njoi !

Thanks, Mahesh! Aesthetically, I am with them. Need to do a major reorganization, if I were to retain this place. Current status looks bleak. I have convinced dad (but that counts for nothing). Next level, Wife & Mom. Didn't expect the both to gang up. Need to hatch a strategy now.

Pictures Arun ! Congrats ! I told you the dipole bass is most realistic of all other bass and could put high end subs to shame. If your fronts are good down to 100-120hz, you may like to cross them around 120hz. This will tighten the bass and confine them to their true region of duty. They will keep performing better and better with any upgrades in source or amps. I myself could not measure any end to betterment in performance with tweaks. It looks like indefinite road. They don’t cease to amaze me.
Also, Experiment and You may find good placement acceptable to all.

Apologies. I did not have time to take pictures as there was too much mess to be cleaned up in the living room. Your assessment was bang on target. I think the four drivers are giving a huge advantage. Since the SPLs are reached with minimal power, there is hardly any distortion.
I have the LFE set at 120 hz. Only two mods before AVR calibration:
- Adding weight over the frames (scouting for the right colour granite)
- Adding gym matting
All the activities put on hold because of work. Need to get the cabinets for ceiling speakers and surrounds done. More action after end of the month.

 

[elangoas]

@arunkvivek This is impressive build.. Cheers..

 

[arunkvivek]

A quick question - I find that if I make the SW lay horizontal, it doesn't sound as good as it sounds it is standing tall. Is this because more surface area is in contact with floor? Would using exercise mat beneath the SW or slab of stone make any difference?
I would like to make them lay flat to avoid the imposing presence of 34 inches height.

 

[arunkvivek]

Back to DIY.. warming up with vinyl adhesive lamination of fostex.

 

[manniraj]

Back to DIY.. warming up with vinyl adhesive lamination of fostex.

Now thats coming up very nicely Vivek, congratulations

 

[blackscorpio]

Back to DIY.. warming up with vinyl adhesive lamination of fostex.

Center looks different which is that? Couple pics of the center please

 

[arunkvivek]

Center looks different which is that? Couple pics of the center please

This is the closest I could get owning a Rethm. It's Rethm center channel bought from an FM here. Vocals sound very real on it. It lacks bass though. 120 hz is all it does but magical tonality.

 

[blackscorpio]

This is the closest I could get owning a Rethm. It's Rethm center channel bought from an FM here. Vocals sound very real on it. It lacks bass though. 120 hz is all it does but magical tonality.

Nice thanks for taking time.

 

[Spinekar]

This is the closest I could get owning a Rethm. It's Rethm center channel bought from an FM here. Vocals sound very real on it. It lacks bass though. 120 hz is all it does but magical tonality.

They look magical