H-Frame Subwoofer & Other HT speakers build

[Nishant Rastogi]

Regarding the centering of acoustic center of the two woofers each side in the H frame, just don't care. I too saw it in some build and I am doubtful if it makes any difference when you cross them below 150Hz.

Using 15" in H frames for music or HT is a brilliant idea and if executed correctly, it will shame 10X famous HT subwoofers, I can bet. Two 15" drivers each side can shake a floor.

Regarding your dilemma on Push Pull or both front firing drivers, there is a nice idea to easily do it and find what you like better.

Let me clarify first, if you mount two drivers in an H frame, both front facing and wired in phase and parallel, its push-push or pull-pull.

If you reverse one driver and they face in opposite directions and are wired in parallel BUT out of phase, its Push-Pull.

In both the cases, the driver sensitivity takes a theoretical 3dB gain. In both cases, pleasantly surprising, the dual driver H frame, the setup Fs is lower than the Fs of the individual driver.

In case of Push-Pull the system Fs is lowest. However in Push Pull the 2nd and 4th order harmonics get cancelled at the cost of deeper bass. The Push-Push H frame does not dig as deep as Push Pull but its very musical. Since the GRS have 29hz Fs, so you may end up liking the both front firing H frame.

A very nice way of making H frame and easy experimenting is, make one individual H frame for each of the four drivers and arrange them as you like and find out. That is, side by side each channel or one above other, each channel and even one reverse backwards for Push Pull side by side or one above other.

I hope it helps. I summed up my own experience from experimenting with H frames. One above other in H frame and front firing was most musical for me with no dearth of earth shattering deep bass. 6" deep sides are good enough. I like to give the driver more space width wise than on the top and bottom in an H frame from the driver frame.

(Its hardly a good idea to put any driver on a break in drill. Play them for some time is much better)

My H frame with 15prv1000v2 with minidsp
High pass at 35 hz - 24db
Low pass at 150 hz - 48db
With just 3 point boost

 

[arunkvivek]

My H frame with 15prv1000v2 with minidsp
High pass at 35 hz - 24db
Low pass at 150 hz - 48db
With just 3 point boost

The H frame looks lovely - Flush mounting and the beading on inside edges look very nice.

 

[arunkvivek]

After a long break, I managed to do finish the cabinets for surrounds and ceiling speakers (totally 3 pairs). Right now, I am letting them break in as sealed speakers for the moment as the rest of the items related to the build are delayed in transit due to lockdown.

Magnat IC62 cabinet was purely a trial as TS parameters are not published anywhere. I emailed Magnat customer care and they said they did not have that info as it was meant to be put in ceiling. i had to check hifi-forum.de and somebody had built a 31cm X 31 cm X 12 cm box and said that it worked well and somebody had suggested 12L box with a 10cm port. So, I decided to take chance (not that i had any other alternative!!) and build boxes of the size - 10 inches X 11 inches X 8 inches (ID). I did not fill the cabinet with any damping material. I just mounted the baffles with screws and screwed in the driver to test.

Magnat IC62 has nice mid-bass and sounds very open even without break-in. I am almost convinced to leave these as sealed speakers only.

Tangband W5-1611SAF was modelled in WinISD for 13L box with 55 hz tuning and is on break in as well. It is taking a while to break-in and is still improving. I lined up the innards with sofa foam ( 1 inch thickness) but I think i should be running them without the foam to see if improves airiness. TB definitely needs a port.

I did not build any network for baffle correction or filters for frequencies as all of them are effect speakers and don't expect them to work below 80 hz (until which they are very steady in volume output). I am trusting AVR calibration to deduct the ideal frequency for cut off.

The difference in size TB - 5 inches vs Magnat 6 inches is very evident in loudness. I am so tempted to put the Magnats as surrounds and mount only one pair on the ceiling for atmos. Will try to pose some build pics during the weekend.

 

[arunkvivek]

Update after a long gap.. finished mounting the magnats to the ceiling. Yet to do wiring..more drilling and fixing conduits for the wire. My family is relieved to see that most boxes have been removed from floor. I have been given final warning to stop further DIY transgression and fold the carpentry table.
Still have two more builds in anvil.

 

[arunkvivek]

The room is almost done.. need to sort out wire management behind AVR. Had a few demo videos run. Atmos is awesome.

 

[arunkvivek]

It has been quite a while since I have updated this thread. There is a slight push back for the H-frames. Is it possible to put these subwoofer drivers into a Ripole build?

 

[arunkvivek]

I happened to finish up a pair of Frugel horns MK3 using Tang band W5-1611SAF. The tonality of these speakers are awesome. They don't go as low as Fostex horns but bass is extremely fast.

Also, I used WPC board for building instead of MDFs and Plywoods. I do not know if if any other DIYers tried using WPC. I can say for sure that they do not sound plasticky at all although the board is a plastic composite. The build was a joy as I didn't have to deal with flying saw dust. The white twirls from trimming and cutting are easy to clean at home. Also, cutting the curve of side panels was a joy as jigsaw cut through the 18mm WPC like butter (it struggled with 4mm ply that i bought to build a template to use my trim router). I could sand all the slopes on the baffle edges as per build plan with very little effort. I do not have have clamps and hence had to predrill holes and nail the baffles. But if clamps are available, just adhesive should be sufficient. Also, the white color of board is so good that we need not paint or laminate it. Nevertheless, i painted them with blue color (left over paint at home) and they look good. I used metal primer on wpc after checking a few youtube videos.

I made them with removable side panels so that i could do change the stuffing. I started off with 180 gms of polyfill. Mids were extremely lean. So, i reverted to the recommended 120 gm range but the bass became boomy. after a couple of iterations, i settled at 150 gms of polyfill. At this level, Mids are meaty but bass is not boomy. Bass is audible until 70 hz -65 hz. Crispyness and immediacy is something very different to what i have listened so far (Elac BS-243, Tannoy bookshelves and Fostex Jericho horns). Also, placing them close to rear wall is very much a necessity for decent bass if it is a large room. I have them in dining hall with open kitchen (15 X 24 feet). They are able to fill this space without going past 50% volume in the amp. But, bass is lost if i move it one foot into the room. So, FH MK3 is not for large rooms.

The use of Tangband W5-1611 SAF has allowed me to use cheap amps (douk audio/SMSL) as speakers have a sensitivity close to 90 db. They are able to handle good volume as well without strain. They do beam a bit (as noted in reviews in parts express) but noticeable when placed 10 feet apart ( i have them in a room against 15 feet wall). They work really well in small (10X 12) to mid sized rooms (12 X 18) as room gain compensates the lower bass output from the drivers.

I have no measurements recorded. All of my observations are subjective and restricted in comparison to the systems that i use or have listened to.

I have placed them in dining room as access to all other rooms have been denied. I now feel encouraged to build Frugal horns XLs using Tangband w5-2143 drivers as i would love to have something that can fill a large room. I also have a temptation towards high sensitivity speakers like Forte III/IV as i love their bass at low volume.

I need to move these out quickly to start with the next build
Edit: a few pics