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Somewhat practical "audiophile" esk8 audio system plans

Let me preface this discussion by stating that I occasionally skate with well-sealed (foam tip) planar IEMs which sound positively wonderful. I’m perfectly happy with that as my solo rig. I do not expect to achieve anything close to that level of audio quality with anything I can screw, clamp or strap to a board. But, I want to come as close as I possibly can, with a 10lb max weight budget, so that I can enjoy tunes while still hearing traffic, (and maybe entertaining others on a group ride.)

While tunes on a board is silly/dangerous/rude/impractical on many levels, I know it can be done, and want to have some fun fooling around with the project.

Primarily as an exercise for someone else with a Lacroix Lonestar, I tried to engineer a decent system with some bass within that weight budget. I have a few ideas I’d like to bounce off anybody here with something to add.

  1. Instead of wasting energy, bulk, $ on a DC-DC buck converter to power 12V-24V audio gear, I finally found a well-regarded chip amp board happy with a single-ended DC supply up to 50V.

https://www.amazon.com/gp/product/B08FDT855Q/
(It was only $65, and is available for around that elsewhere now.)

The board is only rated to 50V, but the amp chip is happy with 53V, so I’ll have to replace 4x 50V electrolytic caps with 63V versions, then be able to run safely with 12S (50.4Vbat max.) It has 4 separate balanced channels, each of which can provide 150/260W into 8/4ohms at 1% distortion, at least 100/200W of clean power into same = more than enough. It weighs about 9oz. I will use it as a 2.2 amp.

  1. As impractical as they are, since the input impedance of this amp is very high (100k ohms,) this may be a great place to use a PLLXO = passive line-level crossover for bi-amping. The smallest decent crossover I have (Audiocontrol 2xs) is larger and heavier than the amplifier, has unbalanced connections. I’m going to try a 2nd order (12db/oct) balanced PLLXO with 1k, 10k resistors for R1, R2, and 1uF, 0.1uf (100nF) for C1, C2 for a crossover point around 150hz.

Alternatively, if I can push the crossover point to around 1khz, I’d simply use a 2nd order speaker level crossover with air core coils, MKP caps. The woofer I chose below may or may not sound nice at 200-1000hz.

Alternatively, I can use the new saltine-sized DSP board from partsexpress to make a 2-way active crossover, but I hate to go back to the digital domain after such a nice DAC/PRE (Earstudio ES100.) It comes pre-configured as a 2-way crossover, with adjustable xo point and levels via the onboard pots, but it’s not balanced. (I really want to stick with balanced signal cabling as the board produces a LOT of interference, and I don’t want to waste bulk/weight with metal shielding.)

  1. BASS is hard to come by on a weight/size budget, but I’ve got gobs of power to play with. I tried one of these in an Apache 2600 case boom box, is fine for stationary listening, but need more to cut through the noise when skating. (I tried skating with it.) Tang Band W6-2253S 6-1/2" Low Profile Subwoofer
    I’d like to use a pair of these. I’m thinking of making a wedge shaped enclosure the width of the deck, with one facing up/forward, the other up/back, (triangular sides,) with the amplifier stashed in the bottom. I usually prefer the sound of a sealed enclosure (or open baffle) but these could use a bit of help on the bottom, would benefit from a tuned enclosure. If the enclosure is spaced up from the surface of the deck a tad on rubber feet, I’d have room for a single 8-10in passive radiator underneath or a pair of 5.25-6.5in passive radiators on the triangular end caps.

Alternatively, I have a pair of Tang Band W6-1139si, which might sound better, but weighs more than 2x as much! Likewise, I’ve got a W8-1363SB to try too, but one of 'em weighs more than 8lbs.

The first (shallow) subwoofer I mention, used in the boombox, want to use 2x here, is the lightest weight 6.5in woofer I found by a country mile. It’s around 2lbs. The next lightest contender was around 3.5lbs, and I’d need a pair of either.

On a cabinet-size / weight / size budget, these 3 Tang Band subwoofers are about the only game in town. They make smaller ones (5-1/4, 3in, 2in) but they are too small to make any sense here… I’d need too many of 'em and they would cost considerably more in the quantity needed to equal a pair of either of the 6.5in.

  1. In lieu of proper bass, it might be “enough” to use a pair of bass shakers secured to either end of the deck… I’ve never tried them in a home theater, might be fun. In this case, I’d run the “tops” full-range.

  2. I’m on the fence about what to use for the “tops”, leaning toward 3.5in neo magnet “full-range” cone speakers. I had great results pushing 50W/side into 3in FR speakers on a recent boombox build, want a bit more powah. The pair will weigh about a pound.

  3. There are 2 very interesting new-ish choices for tops: There are now knock-offs of Bohlender & Graebner planar tweeters & mids, for 1/3 the price, some of which can be crossed at only ~500-700hz. There are also now high power 1in and 1.25in Corundum (synthetic sapphire) tweeters for $50-$60 that are good down to 800-1000hz. Either one would get the XO point “out of the way”, vastly improve dispersion (in at least 1 axis) vs the dinky cones.
    GRS PT6816-8 8" Planar Slim Tweeter 8 Ohm
    https://www.parts-express.com/Peerless-DA25TX00-08-1-Corundum-Dome-Tweeter-264-1676
    Peerless DA32TX00-08 1-1/4" Corundum Dome Tweeter

  4. Speaker attachment to the board??? I propose a prism shape enclosure for the woofers (and amp) above that will sit top center on the deck. For the highs, I’d like to share the truck top plate bores to mount a simple small pear shaped baffle front and rear. When I stand on the board as I would ride (goofy), torso at about a 45deg angle, looking forward, the front speaker is ahead of and to the right of my right shoulder, rear speaker to the left of and behind my left shoulder… both aimed up at my noggin.

  5. Source / input: I absolutely love the Earstudio ES100 bluetooth receiver, which has a 4V p-p balanced output. It’s the size of a matchbox, battery lasts 12hrs+. There are now better receivers with a somewhat hotter signal, DSD support, DSP EQ for $20-$30 more, but no point in upgrading for this project unless the speakers are proven to sound good.

Anyone have any thoughts on this planned audio rig? I plan to deploy it on my already heavy-as-hell Lacroix Nazare. Looking at some long-distance skates this Summer, serious tunes would be quite nice.

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Not gonna lie, I don’t know shit about speakers and it seems like you know your shit already.

The only one I can think of who allegedly knows about speakers is deckoz but he left us.

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I know, what he’s talking about. :joy:
I don’t know, where the fuck he wants to integrate two 8" subs and all the electronics in a nazare… (In a room you only need 10W for a loud experience and 200W peak, holy moly)

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Hey if I wanted to build a portable bluetooth speaker that could kick the the shit out of a JBL Boombox, would you be able to tell what parts to use?

On the cheap…

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I wouldn’t cheap out on that topic, but you can have a best bang for the buck. I would have to search.

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téléchargement

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To say it better. Home theatre. :sweat_smile:

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You might be better off with car stuff that designed for shallow mounting or do you have plans to run a minidsp or something? I have some nice audio stuff at home but for a eskate a good loud bt speaker might be more practical

Like the biggest problem will be bass. You can’t just cheat this a small box will sound worse I really see that as the biggest obstacle. I’d recommend a baffled open air dipole setup for your mids/highs and a small box for a 6" sub if you’re going nuts. A dipole setup outside will easily sound the best it can so fuck the box for mids/highs. Also porting the box will help with more bass but can bottom out drivers I’d def look into car 6" with the higher linear excursion since to have any bass youre going to need it I don’t think the tang band will have it. 8" might be the smallest you can get any good beefy sub for screwing around outside too so not sure if you can work with that.

Sorry I read the beginning and started writing you are adressing most of this. I’d just say the shallow mount subs suck, you need a whole lot more surface area and the mini dsp is a good way to fix everything easily without an eq.

Ill repost this because the board gives an aura almost, this might be all you need (3:34 mark)

This is the more audiophile idea, reduce these to essentially a box with a tweeter on it:

Actually if you do an ohm type the dispersion is better for everyone to enjoy so any 360 drivers?

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I guess you will be able to blast some serious sound but given you’ll be using it in open area with lots of parasitic ambient noise, you might just not be able to achieve audiophile level quality in these disastrous conditions even with a crystal clear rig.

Now just a thought, have you tried recycling a modern Boombox? Not a pocket unit like UE, JBL or similar but a real Boombox.

Sharp, JVC and Pioneer and there’s also another brand which I forget… These guys still know their hand if you can grab one. I have an old Sharp Boombox in my parents garage, that thing was impressive blast on a wall charger but anemic on small batteries, never tried to make a new battery for it tho!

Something like this

Other options for lightweight purpose, isn’t there anything powerful enough in the portable amps? Given you’ll somehow trash around with your board, something like cheap couple Fiio or BK amplifiers fed through a small bec and feeding your speakers?

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as documented by the dude who ghosted, @deckoz

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I know all the reddit kids love putting motors inside their wheels.

What if you made four wheels… …out of woofers

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Clever placement but you get it wrong Brian, IMHO he should have tweeters facing upwards for the crisp mid to high and have the woofers face the ground for strong bass reverb and have space to give them a box of breath.

Else the bass will just muddy up and leave in the empty sky! :cloud:

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I love the idea, with propper RGB lightning it would make for quite a spectacle. On group bycicle rides in Riga we have one guy with woofer mounted on the back and RGB lights. This would definetly be upgrade to that.

Regarding your setup, as others mentioned, biggest problem is air space for woofer to work. Other big problem is the direction. In our cycle group rides, if you where in opposite side of woofer, you pretty much heard nothing. So there should be at least 2 speakers facing both directions, or maybe one facing downwards?

Other options I see is having the woofer on the bagpack:
image
that way you can integrate both, the batteries and airspace there without many restrictions. But it’s giving up on the idea at that point.
You can also add a smaller skateboard with woofer similar to how it was done here:
image
That way you have a lot more freedom with the air box, as well as direction of speakers and batteries. If done right it would have more of an effect, as well as providing an amusement for rest of the pack.

I would also avoid using same battery packon the board for feeding any kind of powerful speaker. For any sortof electronics it’s not good to have uneven DC voltage, unless specifically made so.

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Not 8’s… a pair of 6.5’s. I tried a 2x50W + 100W 2.1 TPA3116 amp board powered by a 6S4P battery in the boombox, neither the amp nor single 6.5in woofer were “enough” to enjoy while wearing a helmet. Those power numbers are very misleading. The boombox amp puts out maybe 25W of clean power into each of the tiny 3in full-range speakers which is more than enough. However, these little 2lb 6.5in subwoofers are not very efficient… the 50W of clean power from that amp is simply nowhere near enough, nor could one of 'em do any better with more clean power. I just want to use a pair.

I do NOT expect to need more than 100W of total power to drive the system when finished… I picked that amp board because it could be driven directly from the main 12S battery pack, eliminating the need for a (second or different) DC-DC converter. The stock buck converter in the Nazare handles a measly 2A = 24W.

Any store-bought boombox or bluetooth speaker smaller than a loaf of bread that makes decent bass does so with the aid of a very complex cabinet tuned to reinforce lower bass frequencies. I don’t h

Looks like a legit 2.1 setup (w/o actually reading the build log) but I face more sideways as I skate, want one small “top box” at each end & a pair of larger woofers in the middle of the deck facing upward. If I wanted to listen to NPR, this would work great. Not going to cut it for doom/sludge.

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For a boombox, this is easy… Plenty of room to use the cabinet to enhance bass response of small (4in and smaller) woofer. Parts Express sells a clamp & glue & paint & plug & play kit for $129 that gets rave reviews.

Dayton Audio MKBoom Portable Bluetooth Speaker Kit?

I will have NO enclosure at all for the small full-range speakers, which means they will make practically no bass at all under 125hz. It all has to come from the woofers, and in a volume smaller than one half of this boombox. Not easy.

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Never had the pleasure of hearing a pair of Ohm Walsh’s, don’t see 6-figure German Physiks speakers on the horizon for me any time soon :slight_smile: That said, you don’t need to spend $10k+ for true omni sound. I am a huge fan of Gallo stuff with their cylindrical omni tweeters. My little CS-2s have the budget version that only radiate 180deg, but it sounds the same in any seat on the sofa… no sweet spot. Upstairs I rock the Reference 3’s w/ the 300deg tweeters, 5in mid spheres, integral woofers… same thing. So long as you’re on vertical axis, anywhere in the room sounds great… The stereo image shifts as you move.

On the board, dispersion is low on the list, but those large planar tweeters sound phenomenal, just came down from $200ea to $40ea! GRS is the company/brand knocking off the B&G, they’re getting rave reivews on PartsExpress.com.

Nothing in this system is particularly expensive or exotic… Maybe $300-$350 build budget all-in.
The only weird stuff about the system is the passive line level crossover… People use the dopey version all the time, in the form of Harrison Labs Fmod plugs. All they are is a resistor + capacitor soldered into an inline RCA jack/plug. They go for ~$25/pr, and represent less than $1 worth of functional parts. I blew $20 on fancy MKP caps and metal film resistors for this project, to make the equivalent of $200 worth of Fmods.

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Hah that’s funny I’ve been debating selling some of my stuff and getting some galos, mainly because they look cool but I know they have good design.

I really only used the walshes as an example for a 360 firing design for public speakers. They aren’t anything special aside from the special coating and tuning to the box(so yes special,lol) but you could diy some with a down firing full range maybe. Just an idea that could sound cool.

Funny you suggest pulling a trailer… That’s on the summer’s to-do list, not to carry (audio) gear, but to allow my dog to join me :slight_smile:

Re not hearing anything when skating “out of the line of fire”, bass radiates 360deg from 80hz down, and at least 300deg from something like 150hz down. Directionality of sound is frequency dependent.

For the most part, mids and tweeters need to be aimed at the listener, and response drops off badly when off-axis either horizontally or vertically. What’s counter-intuitive is that larger mids and tweeters, and those mounted on wide baffles, are MORE directional than tiny ones. The flat planar tweeters, gallo’s cylindrical tweeters cheat this in one axis… They radiate high frequency sound very widely in one axis, terribly in the other… Great across the short axis, terrible across the long axis. Even with 7in long planars, the sweet spot vertically is only a couple feet at listening distance. Since my position on the board is rather fixed, but I swivel my torso, if I go with the long skinny planars, I’ll mount them sideways for better vertical dispersion so it sounds the same as I crouch vs stand.

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What is your goal? Good sound for yourself, also for your riders or for everyone around too?

Sorry reread original post…entertain some group riders as well