10F/8424 & RS225-8 FAST / WAW Ref Monitor

[xrk971]

Design for 10F/RS225-8 TL Floorstander

Here is the design for a floorstanding transmission line (TL) version of this speaker. The cabinet is 40in tall x 16.5in deep x 10.0in wide. It will used the same crossover as the standmount. Sensitivity is 82.5dB at 2.83v and 1m. The predicted -3dB point is about 31.5Hz. The falloff slope of the bass is hgihly dependent of the level of stuffing used in the TL. I modeled it with moderate stuffing in the first third, very light stuffing in the remaining length. Eggcrate foam could be used to line two walls of the long section in the back and the bottom horizontal path. It will take some experimentation to adjust to taste. A removable back panel is suggested to allow adjustment of stuffing. This design is untested and it is recommended that a prototype be made in XPS foam before committing a wood build. The rear chamber for the full range is a 9in tall sports cone/pylon (of the type used for soccer practice). The cone will protrude a bit into the back path, but won't affect the flow much. Make sure you seal the joint where it penetrates the wall. The cone should be stuffed with fiberglass or polyfill, progressively denser towards the vertex. Leave about an inch clear behind the cone. The main TL needs to be airtight relative to the cone flange.

Plan from SW model, note that sidewalls are not shown for clarity, thus cabinet external width is 10in:

Predicted SPL for 2.83v at 1m:

Predicted impedance:

Predicted RS225-8 cone excursion at 50Wrms (max limit for the driver). Total max power into speaker before XO which divides power into full range and RS225-8 is circa 100Wrms:

Note that if your amp can put out more than 100Wrms, it is highly recommended that you use some sort of active high pass filter to prevent frequencies below 30Hz being fed to speaker at high volumes.

 

[zman01]

Nice design X, and the TL goes plenty ow.

 

[xrk971]

Thanks! There might be a smaller (but larger than the sealed) standmount TL that might get a little bit lower than the current sealed. I will have to look at some of the different folding schemes some more. But since we were looking at floor standers I figure make it big and let it go low. If you listen to reasonable sound levels, there is no need for a subwoofer here.

 

[Vunce]

Excellent X!!
This is exactly what I was looking for
Would all the internal 90° outside corners along the transmission line path benefit from being shaped by a router roundover bit?

 

[xrk971]

No, not really - the purpose of corners and turns in a TL is so that it filters out the higher frequencies via losses. Having rounded corners would decrease the filtering. Plus it’s a pain to do. Maybe just the outer ones and the last corner before the vent to reduce turbulence since the velocity is highest there.

 

[Mas Penk]

Here is the design for a floorstanding transmission line (TL) version of this speaker. The cabinet is 40in tall x 16.5in deep x 10.0in wide. It will used the same crossover as the standmount. Sensitivity is 82.5dB at 2.83v and 1m. The predicted -3dB point is about 31.5Hz. The falloff slope of the bass is hgihly dependent of the level of stuffing used in the TL. I modeled it with moderate stuffing in the first third, very light stuffing in the remaining length. Eggcrate foam could be used to line two walls of the long section in the back and the bottom horizontal path. It will take some experimentation to adjust to taste. A removable back panel is suggested to allow adjustment of stuffing. This design is untested and it is recommended that a prototype be made in XPS foam before committing a wood build. The rear chamber for the full range is a 9in tall sports cone/pylon (of the type used for soccer practice). The cone will protrude a bit into the back path, but won't affect the flow much. Make sure you seal the joint where it penetrates the wall. The cone should be stuffed with fiberglass or polyfill, progressively denser towards the vertex. Leave about an inch clear behind the cone. The main TL needs to be airtight relative to the cone flange.

Plan from SW model, note that sidewalls are not shown for clarity, thus cabinet external width is 10in:

Predicted SPL for 2.83v at 1m:

Predicted impedance:

Predicted RS225-8 cone excursion at 50Wrms (max limit for the driver). Total max power into speaker before XO which divides power into full range and RS225-8 is circa 100Wrms:

Note that if your amp can put out more than 100Wrms, it is highly recommended that you use some sort of active high pass filter to prevent frequencies below 30Hz being fed to speaker at high volumes.

Nice design X
Do we still have put a pyramid (dagger) isolator between the woofer and 10F??

 

[zman01]

Mas Penk,

Yes - the wide-band unit is still isolated from the woofer:

The rear chamber for the full range is a 9in tall sports cone/pylon (of the type used for soccer practice). The cone will protrude a bit into the back path, but won't affect the flow much. Make sure you seal the joint where it penetrates the wall. The cone should be stuffed with fiberglass or polyfill, progressively denser towards the vertex. Leave about an inch clear behind the cone. The main TL needs to be airtight relative to the cone flange.

 

[xrk971]

Here is the 9in sports cone that I have on hand (and hole dimensions for penetration based on - although best to custom check with your own cones):
Cintz 9" Orange Field Cone... https://www.amazon.com/dp/B002RTEU2Q?ref=ppx_pop_mob_ap_share

Great for full range speakers and soccer practice.

I like how the CAD drawing looks. I don’t think I have ever posted a CAD drawing before for a plan. Usually hand drawn - but I wanted to make sure there were no strange fitment issues.

 

[xrk971]

Regarding stuffing or damping, you might try copying what PMC does on their TL's using eggcrate foam:

An externally hosted image should be here but it was not working when we last tested it.

N.B., there seems to almost always be extra foam to constrict the point right after the woofer. This can also be done with a wad of fiberglass and I bet is one of the main adjustments of the sound quality.

 

[xrk971]

For those wishing to attempt this build in 1in XPS foam, grow the exterior dimensions as needed and maintain interior dimensions. The speaker will be perhaps 15.5in deep and 42.5in tall. The internal width will remain the same but exterior width will be about 10.5in. Also note that there is quite some latitude to be off by a half inch here and there - don’t stress and worry. But do try to keep the final exit port at 2.5in or so. In fact, the initial 8in wife channel can easily be 7.5in and 6.5in can be 6in to keep the speaker smaller if you wish. That won’t affect the performance too much and will actually increase the bass SPL a tad at expense of extension.

 

[xrk971]

A good source of long pieces of eggcrate foam are mattress liners at your local discount box store (in US). Maybe $15 and enough to make many speakers.

Or like this:

Eggcrate Mattress Cushion 34 x 72 x 1.5 Convoluted

You can use the nice grey eggcrate foam pads with adhesive back from PE too, cost a bit more but very convenient and works well.

But even better than eggcrate foam are the melamine magic eraser pads (aka BASF Basotect). I would save those for lining the rear (including the side) walls facing the back of the driver. The will prevent any back reflection from getting back to the driver.

100 x Magic Sponge Eraser Cleaning Melamine Multi-Functional Foam Cleaner https://www.amazon.com/dp/B01LZB2HOQ/ref=cm_sw_r_cp_api_i_Gb3.Db8V3EBJC

Or

US $3.31 15％ Off | 100 Pcs/lot Wholesale White Magic Sponge Eraser Melamine Cleaner,multi-functional Cleaning 100x60x10mm
AliExpress

 

[poseidonsvoice]

X,

I think an impedance with phase curve would be useful for some builders out there. Please post it if you can in the 1st post of the thread and perhaps update the GB first post with that measurement as well. You have posted the phase curve that the mic measures in room but I do not see the electrical phase and electrical impedance curves, i.e. what the amplifier 'sees.' Easy to measure and quick with a Dayton DATS v3 or equivalent.

Thank you!

Best,
Anand.

 

[xrk971]

I suppose I forgot to post this when I last posted the XO on on Jan 11, 2018.

Just to have it all in one place. Here are the Xsim predicted performance curves for 10F/8424 an RS225-8 crossover from the Jan. 11, 2018 version (latest):

Electrical Impedance:

Frequency Response and Acoustic Phase:

Step Response:

 

[sychan]

Sorry, the key to this speaker is the bass unit. The RS225-8 is actually a unique driver and not really available from any other manufacturer even at a higher price point. The key is very flat wide bandwidth that goes up to 5kHz. This allows you to use a simple first order XO with little correction of notch filters etc.

I was wondering if you could speculate about 7" (actually more like 6.5") Anarchy woofer being used for a more compact enclosure. It has a pretty flat response and low distortion:

( from Test Bench: Exodus Audio W06-017R “Anarchy” | audioXpress )

And the Vas is only about 11 liters. The 4 ohm version even matches the efficiency pretty well. Assuming a DSP XO and a few class D amps, do you think the same quality could be achieved in a smaller enclosure?

 

[xrk971]

It looks ok, and if using DSP, almost any driver will work since you have a PEQ to smooth out the rough spots. I would recommend using a Harsch quasi transient perfect XO for a DSP implementation. 4th order BW on woofer and 3rd order Bessel on tweeter. Delay tweeter by specified amount based on XO frequency.

S. Harsch XO

Regarding same quality sound: The RS225-8 is a unique driver with unmatched T/S parameters at even higher price points from any manufacturer. It’s what makes this speaker possible with such a simple passive XO.

With a 6.5in woofer you are at a bass disadvantage. And smoothness and distortion are not as good. There’s something strange at 500Hz.

The 10dB bump at 1400 Hz will require a notch as that is very audible.

 

[Vunce]

Hi X,
I started on the RS225 FAST TL foam proto boxes today. The sides and rear panel are cut from 1” XPS, the top and bottom will be doubled 1/2” XPS. The front baffle will also be doubled 1/2” foam with a layer of 3/16” plywood to help support the drivers. For stability, a cavity will be created in the base to fill with sand or lead shot.
When the PL300 Foamboard adhesive dries in a day or so, I will start the interior baffle work. Once the transmission line is created then the front exit slot can be cut out.
The driver cutouts, cone install and damping will wait until I have all parts in hand for “real” fitment numbers. Since the XO pcb’s probably won’t be ready, I’ll just P2P the XO outside the box.

Any input/ideas would be more than welcome

 

[xrk971]

Those look great! Boy, they are big speakers!

 

[sarathssca]

some examples of floor standers using dayton RS225 for reference , but they don't seems to be TL designs (didn't found many while browsing)
TW-84 Home Entertainment Speakers | Tech Speakers
JJM-001 Home Theatre Loudspeakers | Tech Speakers

 

[zman01]

Good start Vunce!

 

[Vunce]

The Elves were busy again this evening, the interior pieces of 1/2” XPS were glued in to form the TL. It’s starting to look like a speaker enclosure now
Progress will pause for a bit until I receive all the drivers and XO parts.