Seriatim from InDIYana and MWAF

[jhollander]

Here is my Seriatim (Latin for "in series") build from Ludicrosity InDIYana and MWAF.

The drivers are HiVi RT1.3 tweeter and RS180P-8 woofer. The HiVi RT1.3 WE (round face plate) is a direct replacement.

This speaker uses a series crossover. The crossover transfer functions are shaped similar to the Neville Thiele Method™ (NTM). The slopes are 48dB /octave, eighth order.

I've been playing with a crossover for positioning this speaker on a shelf and near a wall. I've included this “tweaked” cross over along with the original.

If the original crossover sounds a bit fat, increase the insulation behind the woofer.

See the attached PDF for the details.

Let me know if you see any errors.

[isaeagle4031]

Re: Seriatim from InDIYana and MWAF

Great work John. This is a super nice speaker. Kinda glad I didn't have to compete against you twice!

[jhollander]

Re: Seriatim from InDIYana and MWAF

Thanks Chuck.

Also thanks to Wolf for encouraging me to try the HiVi RT1.3 and creating the challenge of designing a series crossover.

A few other comments about this build.

The HiVi RT1.3 tweeter sounds better than its $40 cost. The HiVi RT1.3 WE will look better.

The woofer hole in the MDF box was cut oversize to improve the driver venting. The curved sides were made oversized from ½ inch MDF. The sides were sawn every 3/8 inch to create slots to facilitate bending. The sided were glued to the assembled top, bottom, front, and rear “frame”. The oversized pieces were cut flush with a numbers of saws and hand planes. The MDF slots were filled with wood putty. The box was sealed and sanded multiple times with shellac based primer to eliminate any ripples from the slotting and bending the MDF.

The port was fabricated from ½ inch stock and a 3/8 inch round over was added to the inside opening. Cutting the port in the front baffle is tricky. Generally you want to use a flush cutting bit to cut the port opening in the baffle before you trim the baffle to the sides of the box

I used black peal and stick felt from the craft store to seal the openings between the baffle and the box.

[donradick]

Re: Seriatim from InDIYana and MWAF

Very beautiful design and execution!
Ever since I saw a pic of those I was wondering about them.

[NyxOne]

Re: Seriatim from InDIYana and MWAF

Here is my Seriatim (Latin for "in series") build from Ludicrosity InDIYana and MWAF.

The drivers are HiVi RT1.3 tweeter and RS180P-8 woofer. The HiVi RT1.3 WE (round face plate) is a direct replacement.

This speaker uses a series crossover. The crossover transfer functions are shaped similar to the Neville Thiele Method™ (NTM). The slopes are 48dB /octave, eighth order.

I've been playing with a crossover for positioning this speaker on a shelf and near a wall. I've included this “tweaked” cross over along with the original.

If the original crossover sounds a bit fat, increase the insulation behind the woofer.

See the attached PDF for the details.

Let me know if you see any errors.

Beautiful project and congrats on your first place!

Do you have any off axis measurement ? I'm curious how well your project did off axis being that you cross a 7" driver relatively high (3.8khz ?)

Chucky

[jhollander]

Re: Seriatim from InDIYana and MWAF

The subjective results were good. I do not have actual measurements. Here's pic of the modeled response at 45 degrees.

[HiHoSilverado]

Re: Seriatim from InDIYana and MWAF

Thanks for sharing what looks to be a great design. I would like to build a version of these using the P/E .56cf flat pack cabs (#300-7064) and flared ports. Precision Ports' website port-length calculator suggests using a tube length of about 6.4 inches to tune a 3 inch diameter port to 50hz. Does this sound right? The suggested 2" diameter port length would only leave .5 inches of tube after subtracting 5 inches from the calculated length (per their instructions). See http://www.psp-inc.com/tools2.html.

I built a pair of Zaph Audio SR-71s using the same cabinets and they sound fantastic. However, the SR-71s are rear-ported because the baffle lacks space for a front-mounted flare port. Would rear-mounting the port here seriously impact sound quality (they will go on stands, not on a bookshelf)? If so, any other suggestions for commercially available port alternatives? I am confident I can build the rectangular ports per the provided design, but would like to do the build as off-the-shelf as possible to encourage others without advanced woodworking skills.

I am looking forward to comparing these with my SR-71s down the road.

Winston

[jhollander]

Re: Seriatim from InDIYana and MWAF

The rectangular baffle will change the tweeter response a bit so your result will be different. You can you a 2 inch port without a problem. Rear mount is OK.

If you go rear mount you can use the PE adjustable 2 inch port, http://www.parts-express.com/speaker...table--260-387 length should be 9 to 10 cms.

For the precision port with the original tuning, use a 2 inch port 12.3 cm or 4.8 inches. I’d recommend erring on the short side. The original tuning is 56 Hz.

Use the original crossover if you are stand mounting. Good luck

[HiHoSilverado]

Re: Seriatim from InDIYana and MWAF

Thanks for the input. I will post pics once I get started.

[HiHoSilverado]

So, it has taken 3 years to finally get this project under way (adding a second kid to the family really slowed me down) and I am getting close to assembly. I used the PE .5ft knock down cabinets and made the baffles out of Oak board. The baffles will be finished with gloss poly and the cabinets with white paint to match the trim in my house (my wife’s idea). I have a question about the interior insulation- the specs say Roxul and batting on the sides and back. By Roxul, do you mean mineral wool insulation? Do you use spray adhesive or just cut it fat and press in to place? Thanks, pics are forthcoming. Sent from my iPhone using Tapatalk

[HiHoSilverado]

Crossover and schematic: Sent from my iPhone using Tapatalk

[HiHoSilverado]

First coat of paint on the cabinets: Sent from my iPhone using Tapatalk

[jhollander]

You can use mineral wool or fiberglass in a polyester batting pillow and place it behind the woofer under the port.

[HiHoSilverado]

Great, thank you! Sent from my iPhone using Tapatalk

[jhollander]

From what I can tell in the picture you might be missing a wire. Also I labeled the woofer positive lead. See attached