Zaph B3S + Micro Subwoofer Stands + Active Crossover

[Landspeeder]

Active Crossover: miniDSP 2x4
- USB self powered device and wide range of DC power options (4.5 to 24VDC)
- Volume control by potentiometer on 3pin header - This will be the ONLY volume control on the unit
- Programmed at 200 Hz cutoff between stereo Zaph and stereo subwoofers.

HOW TO POWER THIS?
-Either via a Cell phone USB charger --- or somehow straight off of the amp PSU?
-Parallel the power to this AND the amp from the PSU?
-Some help if possible please!

Amp: 4x100W at 4 Ohm TK2050 Class-T Digital Audio Amplifier Board. Part # 320-335

Amp PSU: 24 VDC 14.6A 350W Regulated Switching Power Supply. Part # 320-316

Subwoofer Idea
- Same profile dimensions as Zaph B3S (5" wide, 8" deep max)
- Height 17" - 22" tall (desktop requirement for ear level Zaphs).
-Tang Band W4-2089 4.5" RBM Mini Flat Panel Subwoofer 4 Ohm (down to 35 hz in a 0.03 ft.³ sealed box)
I AM OPEN TO OTHER SUGGESTIONS on the woofers This sucker is expensive at $70/speaker

Zaph B3S
-Done (Upgraded Crossover pictures below)

[Hdale85]

Wow, beautiful B3S's. They look like pricey cabinets though.

[Landspeeder]

Thanks Hdale.

A 4x8 Sheet of 1/2" Carbonized Vertical 3-PLY Bamboo Plywood from CaliBamboo was $165 for a single (plus a little for shipping across the country). The cost goes down with additional sheets at once.

The only downer to this material is that it is HARD. It wears out blades, router bits, sandpaper, etc FAST. Also, the occasional splinters are LONG and SHARP.

I should be able to build a few projects out of this amount... and no need for veneer (which can be just as expensive), or painting.

The finish is 50/50 Tung/Turpentine followed by about 30 coats of tung (all 100% / natural)... followed by 1 coat of paste wax.

[Landspeeder]

Slightly Upgraded Crossovers (aka, the spare parts bin)

[Landspeeder]

Close up of the bamboo

[Landspeeder]

A couple more shots... then time to start working on the Amp/Crossover tower

[---k---]

Those look great. :T
I got no ideas on how to work out the miniDSP.
I know the miniDSP will be fun, but for the sub, have you considered just using a subwoofer plate amp with a speaker level crossover in it? Seems like a much easier solution and one that is already purpose built for what you want.

What will the source be?

[Landspeeder]

---K---
Thanks!
I am considering wiring a switch to the front and the back. The back switch will provide power to the front switch AND a cell phone charger. I will essentially leave the miniDSP on ALL the time via the cell phone charger.
The front switch will then provide power to the 24V PSU.
Not elegant... but in testing it appears to work fine (still open to suggestions). The miniDSP needs to be on before the source and amp to prevent a bad pop.

I have built a few of Zaph's B3S speakers - They work GREAT with a cheap receiver that will digitally filter out between 150-200 Hz.
Below 100 Hz these speakers hit some serious distortion - Zaph provides a passive filter for those that wish to run with a plate amp but that filter costs more than the active crossover does. Also, with a crossover closer to 200 Hz these can take some serious power! Of course, at 200 Hz proper stereo subs are needed!

While a plate amp will work with a full range wave, it makes these speakers sound Terrible! Zaph has a write-up on this and a measured graph:



Try not to cringe. The source is a computer (all music saved at 320 kbps mp3). I used to use a Xonar, but have since moved to USB DACs (ODAC and Schiit Modi).

[Landspeeder]

DAC/Active Crossover/AMP/PSU idea



Red: Sure Amp 4x100W at 4 Ohm TK2050 -two TC2000 and four TP2050.
Pink: ODAC.
Grey: 24 VDC 14.6A 350W - Regulated Switching PSU.
Blue: miniDSP 2x4 Active Crossover
…
Back PSU panel held on by Magnets. Includes a Mesh Vent
Right Side panel comes off with Hex Bolts. Main Side panels Bamboo Ply
All else Wood Veneer
…
Back From Bottom Up.
AC in
PSU Switch with fuse
Sub L/R out - binding posts
Main L/R out - binding posts
USB miniDSP Crossover in (for programing tweaking)
RCA and 3.5 MM Pass-though (for future use should DAC go down)
USB ODAC in
Front
AMP Power Switch
Volume Potentiometer hooked up to miniDSP

[Landspeeder]

Amp Idea 2.
Bottom slots in side panels AND in bottom horizontal support.
Top back vent - just hook up USB pass through via vent mesh - skip RCA/3.5 pass through for now
Right side panel, again allow via bolt on/off via hex screws.

[Landspeeder]

Subwoofer Speaker Stands:
Tang Band W4-2089 4.5" RBM Mini Flat Panel Subwoofer 4 Ohm

http://www.tb-speaker.com/detail/1230_04/w4-2089.htm

external dimensions of 14"H x 6"W x 10"D
3/4" MDF
two 1" diameter ports that are 8" long each.
Tuned box to 40 Hz with F3 of 37 Hz.

These will be on tall spikes (for listening level)


HELP
The speaker mounts on these suck. They are 1 3/8" Deep.
I have 3 mounting style ideas
1 - On Surface (easy, but not pretty)
2 - Rear mount with face roundover (easy, prettier) - Any issue with this if tuned for a cutoff below 200 Hz?
3 - Flush mount. (tricky... very tricky)

[---k---]

I think I'm confused. I'm a little sleep deprived these days.

Your way is probably better sounding. I'm just not sure I would go through it with those drivers.

I was suggesting: Computer --> amp for the full signal range --> full range signal into the plate amp speaker level input --> plate amp output to the speakers.
So your amp would be powering your B3 speakers and the plate amp would power the subwoofer. You would not use the plate amp low level input like we normally do. The crossover would be done by the plateamp. Here is a picture of the SA100 plate amp for reference. You can see left and right speaker level inputs, and then you see the left and right speaker level outputs. Seems so easy to me.
Maybe the crossover in the plateamp is noisy? Plate amp crossovers seem to be rarely talked about these days, but I don't remember ever reading a complaint 10 years ago or so.

[---k---]

Wow. That is different.
My initial thought was to flush mount by double up the baffle thickness. But you're really looking at tripling the baffle. As you said, it's tricky.

With surface mount, the back side of the driver will be pretty confined i think. You would want lots of backside relief which may be hard to do.
So, I think you're looking at rear mounting. I don't think it will be a problem with a big roundover on the opening and frequencies less than 200hz.

[Landspeeder]

I think surface mount is really out... it is UGLY and you make a good point of tripping up the backside.

Flush mounting is doable, but the routing would be really tricky for me (my routing table and big routers are all in long term storage... so it would be done with a veneer router!)

I think a rear mounted build with a heavy roundover on the driver and ports (PVC Pipe) is probably my best option. I know it does not matter for 80 Hz down... I did not know if it was ok for 200 hz down... Thanks!

MMM... I should probably make the baffles removable should the speaker ever need replacement! The side panels will need about 0.5" routed out for clearance!

[Landspeeder]

'RE to the plate amp.
I did try one with the first B3S I ever built... even after reading Zaphs writeup. Hopefully Zaph does not mind my re-posting his words here:

http://www.zaphaudio.com/audio-speaker18.html

use an active subwoofer crossover!
some of you with plain old stereo receivers will be tempted to to hook up a sub with a plate amp, using the high level inputs, and then run the satellites from the plate amp's speaker level outputs. don't do it. here's why.

[image] - response with plate amp speaker level outputs

a plate amp speaker level output usually has a "1st order" high pass which is essentially just a 100 uf cap. this woofer has a fairly sharp impedance peak at it's resonant frequency. in this box, at this exact enclosure volume, the impedance peak is around 130hz. in the schematic, c0 represents the 100 uf cap. when you combine the impedance peak with the cap, what you get is a huge, sharp peak in the response as shown in the image above.

we can fix that problem with a passive impedance flattening circuit, but i have to warn you, it's not the most cost effective way to do it. you'll see why in the image below.

With something like the Overnight Sensations MT I have NO issues with a plate amp... but it just does not work with the B3S without getting some NASTY sounds... unless one is willing to spend a chunk of cash on passive crossover and at that point I prefer active for the same or less money

[Landspeeder]

Also - I own the DC PSU, the miniDSP, a spare ODAC, and the Sure 4 channel amp!

[---k---]

Ahh. That explains it. You posted the graph previously. I looked at it. I saw the big dip, but it didn't occur to me that was being caused by the plate-amp interaction.
I guess I now need to go back and read the original question.