Project #2: The 'Tenacious Bass 6' and 'Tenacious Bass 8' Subwoofers

[tomzarbo]

Dave,

That came out really nice looking with the paint and exposed ply ends. You know, I like the look of the plywood layers more each time I see someone do it.

Looking forward to hearing your impressions on the combo with the Knobsound 2.1 amp. One thing in your favor in case the subs crossover point doesn't go as low as we were hoping... it may not end up being as noticeable since the active driver is facing down.

Nice! Thanks for posting your progress.

TomZ

[djg]

Running on the Nobsound 2.1 with 100 watts claimed, this sub is just loafing along. Very deep output, nice sound. Well worth building. Somewhat underutilized in this application. No idea of the sub channel crossover point or controlability, but the sub certainly is not putting out voices or other high frequency noise.

This box and PR go much lower than the same TB woofer in a small vented box.

Thanks Tom.

[iglow01gt]

Hi, I love the slot port design of the Tenacious Bass 6 and I was wondering if you ran any design numbers to adapt it for the Tang Band W5-1138SMF?
I have not seen any designs published with using slot ports for the smaller driver and I happen to have one on the shelf.
The ported ones seem to all have reviews that state the round ports are harder to incorporate in the box and they still have chuffing issues.
Thanks,
Tim

[Millstonemike]

Running on the Nobsound 2.1 with 100 watts claimed, this sub is just loafing along. Very deep output, nice sound. Well worth building. Somewhat underutilized in this application. No idea of the sub channel crossover point or controlability, but the sub certainly is not putting out voices or other high frequency noise.

This box and PR go much lower than the same TB woofer in a small vented box.

Thanks Tom.

The Nobsound's claim of 100 W on the sub channel can only be achieved with a 2 ohm driver. The 4 ohm TB sub will see ~65 W rms (clean, < 1% THD) when using a 24 V PS; 40 W rms with a 19 V PS.

The maximum, theoretical, clean W rms for BTL (or PBTL) mode DC powered amps is solely determined by the PS voltage and the driver impedance. The 100 W rms rating of the Nobsound sub channel is the thermal dissipation limitation of the TPA3116 chip (in PBTL mode). For example, at 24 V with a 2 ohm sub, ~130 W rms is possible. But that exceeds the thermal dissipation capacity of the chip (but very possible given certain conditions).

A good ROT for BTL DC amps is: Clean W rms = (Vdc-1)² / (2*R_driver).

[djg]

So, the PE 24V 5A brick is "better" than my 19V 7.5A? The 19V has more watts. Now tell me how inflated these ratings are. Is there a power supply better than laptop bricks? I mean, one generally available assembled or kit?

[Millstonemike]

So, the PE 24V 5A brick is "better" than my 19V 7.5A? The 19V has more watts. Now tell me how inflated these ratings are. Is there a power supply better than laptop bricks? I mean, one generally available assembled or kit?

Yes, the brick will give you more watts into the speakers. In my last post, the last line defines the theoretical maximum power output. The two determining factors are PS V and speaker impedance. A 24 V PS will give you 65% more W rms into the speakers given the PS has sufficient amps to support peak demand. You need to enough amps to get the max power or the Switch mode PS will go into protect mode during peaks and recover within seconds. The 19 V PS will always have less maximum output than a 24 V PS that has sufficient amps, regardless of the 19 V PS amp rating.

A 24 V, 5 amp brick should be good with a 4 ohm sub and 8 ohm L-R speakers.

[djg]

Thank you.

[mzane]

Hi!

I finally finished building the Tenacious 8, which I'd been slowly working on since December! I'm not much of a woodworker but I am serially constructing speakers since I can't afford the sound quality I want otherwise. I needed a subwoofer to pair with my Fusion-8's (https://www.diysoundgroup.com/home-t...alchemy-8.html) and these designs caught my eye. The Fusions were the first speakers I ever built and have a simple poly'd baltic birch enclosure with a flat black MDF baffle. I finished the sub to match, with a wipe-on poly finish and some black pipe legs and skipped the round-offs. I was going to get 8 pipe flanges and connect the bottom to a sheet of wood as yours is, but they're $8 a pop and I didn't want to spend that much on just legs so I just got some ends for the pipe. I may have to acquire some rubber caps if it starts sliding around on the floor.

I've got it crossed over at ~80hz and it sounds great

Notes for others:
- Be careful if you jigsaw out the insides of the holes like Tom does, if you go too fast on the small circle it's really easy to cut where you don't intend. Go slow and leave more room than you'd think you should.
- When painting the speaker insets, I used Rustoleum Painters Choice black primer+paint two in one and it was pretty hard to wipe off my poly as described by Tom, I had to frantically run for some mineral spirits. It may be because my poly layer isn't very thick or because the primer is designed to stick to plastic.
These were the first speakers I ever built and have a simple
- It seems to be impossible to find black screws at hardware stores / Home Depot. I buy silver ones because I'm too impatient for the internet and paint them black.
- Don't be a fool like me and forget how deeeeep that bottom driver is recessed. I bought way too long of screws for it.

Questions?
I accidentally made the box too big by about in inch in every dimension. Should I put something in there to reduce the volume of the box? Or will it not affect the tuning dramatically?
Did you put any stuffing in your 8?

Thanks so much to Tom for the design.

[djg]

Looks nice. I like the legs.

[tomzarbo]

Hi!

I finally finished building the Tenacious 8, which I'd been slowly working on since December! I'm not much of a woodworker but I am serially constructing speakers since I can't afford the sound quality I want otherwise. I needed a subwoofer to pair with my Fusion-8's (https://www.diysoundgroup.com/home-t...alchemy-8.html) and these designs caught my eye. The Fusions were the first speakers I ever built and have a simple poly'd baltic birch enclosure with a flat black MDF baffle. I finished the sub to match, with a wipe-on poly finish and some black pipe legs and skipped the round-offs. I was going to get 8 pipe flanges and connect the bottom to a sheet of wood as yours is, but they're $8 a pop and I didn't want to spend that much on just legs so I just got some ends for the pipe. I may have to acquire some rubber caps if it starts sliding around on the floor.

I've got it crossed over at ~80hz and it sounds great

Notes for others:
- Be careful if you jigsaw out the insides of the holes like Tom does, if you go too fast on the small circle it's really easy to cut where you don't intend. Go slow and leave more room than you'd think you should.
- When painting the speaker insets, I used Rustoleum Painters Choice black primer+paint two in one and it was pretty hard to wipe off my poly as described by Tom, I had to frantically run for some mineral spirits. It may be because my poly layer isn't very thick or because the primer is designed to stick to plastic.
These were the first speakers I ever built and have a simple
- It seems to be impossible to find black screws at hardware stores / Home Depot. I buy silver ones because I'm too impatient for the internet and paint them black.
- Don't be a fool like me and forget how deeeeep that bottom driver is recessed. I bought way too long of screws for it.

Questions?
I accidentally made the box too big by about in inch in every dimension. Should I put something in there to reduce the volume of the box? Or will it not affect the tuning dramatically?
Did you put any stuffing in your 8?

Thanks so much to Tom for the design.

mzane,
Looks good! I like the plywood end grain type of look when it's done with good quality ply like you have. I didn't stuff mine with anything that I recall.
I usually put enough poly on my cabs to get a decent sheen, 6-7 layers usually. I don't know if I mentioned it or not previously, but I make sure the rag is fairly damp when I wipe off the excess black paint... I've never had an issue with it trying to stick, even 3-4 minutes afterward. You do need to rub it just a bit for it to fully come off if you wait a few minutes. Maybe you didn't have much poly built up or the rag wasn't damp? Dunno, but thanks for the info on that. I'll pay extra attention to it the next time I do it to look out for potential problems.

The extra volume shouldn't change things too much. I now have mine tuned a tiny bit lower than the setup I published by using more weight with no issues... small changes shouldn't change things too much. I'd suspect the bigger change to the design would be the larger distance between the driver and the floor in your version as opposed to mine with only 1.5" from driver to bottom plate.

I'm glad you like it and thanks for posting pics of your build.

TomZ

[mzane]

The extra volume shouldn't change things too much. I now have mine tuned a tiny bit lower than the setup I published by using more weight with no issues... small changes shouldn't change things too much. I'd suspect the bigger change to the design would be the larger distance between the driver and the floor in your version as opposed to mine with only 1.5" from driver to bottom plate.

Yeah I sure expected the pipe to screw further in but there's a lot of spacing remaining on the threads. Which way would it move the tuning? I may have to go to a wooden base anyway, I'm getting a lot of floor vibration as is. I'm not sure if there's much to do about it though. Also, this thing will definitely slide around on a wooden floor with the legs as is.

Another note to others is the passive radiator comes with gasketing but the woofer does not and you'll almost definitely want some. I got some after I had finished the build and it makes a big difference.

Oh also, I totally skipped the compartment separating the amplifier. If it rattles, I may add something in, but I'm not sure that'd make a big difference anyway. Tom, it kind of looked like you included it because you changed the design?

Michael

[tomzarbo]

Yeah I sure expected the pipe to screw further in but there's a lot of spacing remaining on the threads. Which way would it move the tuning? I may have to go to a wooden base anyway, I'm getting a lot of floor vibration as is. I'm not sure if there's much to do about it though. Also, this thing will definitely slide around on a wooden floor with the legs as is.

Another note to others is the passive radiator comes with gasketing but the woofer does not and you'll almost definitely want some. I got some after I had finished the build and it makes a big difference.

Oh also, I totally skipped the compartment separating the amplifier. If it rattles, I may add something in, but I'm not sure that'd make a big difference anyway. Tom, it kind of looked like you included it because you changed the design?

Michael

Michael,
Having the driver closer to the floor would push the tuning a bit lower as some of the air under and directly next to the cabinet/driver would be coupled to the driver's cone, adding to the vibrating air mass. Not a big change, but just trying to make the point that either wouldn't change things too much to be an issue either way. I think if you did add a base similar to what I constructed, it may reduce floor vibration issues because I don't seem to have any at all, though I use mine on carpet.

The TB 8 was supposed to be a slot vented design originally, so yeah, I did end up changing things from the original design, but I tend to make sub-enclosures for amps these days as I just don't like the idea of the amp itself being the air-barrier...too much vibration for my taste. I do like the Yung amps, though, real solid and good performing for a good price.

TomZ

[djg]

I put a base on my Tenacious 8 with a gap 1/4" less than Tom's spec, but I put a speaker sized hole in it. It is on carpet. I am very happy with the results, no idea if the result is much different than original.