Fast forward to today, and I finally collected the drivers I figure would offer the performance I was after.

I have a pair of GRS RT1.R-8 ribbons, HiVi DM-7600 dome mids, and Dayton SIG270-4 woofers.

Design goal here is obvious so I will not go in to too much detail. Suffice to say a flat response from 27Hz to over 20kHz and a smooth off-axis.

These are intended to be used in a local studio as playback monitors provided they are willing to pay the price lol.

Preliminary modeling (using 0.5 ohm series resistance):

At first blush it might look a little too "roller coastery", but the ripples are actually +/- 0.3db so inaudible. Pretty sweet woofer as far as that goes. It will handle 70W all the way down to 24Hz! It should handle the volume twist with ease. What it really means is at normal playback volumes (80-85dB peaks) thermal and mechanical compression will have zero issues. This translates to very clean bass and lower mids.

The only thing I am wobbling on is driver arrangement. Do I do all vertical TMW or do I do a horizontal W/TM? The vertical should theoretically offer some advantages over the W/TM, but the W/TM will appeal more to musicians due to the sheer number of such designs penetrating the recording studio world.

So anyways, cabinet work for Cabrini the Last is well underway so in the meantime I have started this one.

Each channel consists of five independent cabinets arranged in an adjustable curvilinear array. From top to bottom, the layout is "MMTMM" + sub (see drawings below).

Each midrange and tweeter driver is given its own small cabinet and each small cabinet is, in turn, connected to the other small cabinets using slotted masonite brackets. This makes it possible to adjust the relative position of each driver in the "X" and/or "Z" dimensions based on measurements and listening tests.

I initially plan to use very short 2 and 3 inch long slotted masonite brackets that will allow for very small driver micro adjustments. These small adjustments will be somewhat similar in concept to those used by Focal's Grande Utopia or Wilson's WAMM Master Chronosonic loudspeakers. If larger adjustments are needed, I can simply swap out brackets of different lengths.

INITIAL DRIVER SELECTION:

Tweeter: Bozhen CQ76B ribbon (1 per channel).
Midrange: Tectonic TEBM46C20N-4B BMR's (4 of them per channel).
Woofers: GRS 12SW-4HE (1 per channel).

Crossover targets: T/mid: 1-3kHz passive LR2.
Mid/woof low pass: Plate amp set to 150 to 200Hz.
Mid/woofer high pass: 150 to 200Hz passive LR2 with parallel notch to dampen the impedance peak.

I had to announce this before the SDC hit for sale prices if people want to purchase items this weekend, however, QnA will likely be limited as my time is as such before Friday.

We have not done 4ways before for the theme, nor are they commonplace projects in attendance. That said, I want to attempt one at some point, but some others may find it daunting. So the 3way option is for those that don't want to go that direction. It still stretches the midrange bandwidth for an inherently less easy blending.

The woofer has to be the beefiest 6-6.5" nominal driver I've ever had or used. Frame curve to curve is about 7", but mounting hole center to center is 7.5". By Dayton measurements, even with the pincushion cast frame, I would call this a 7.5" woofer (7" nominal, not 6" as it is labeled). Other features include a 2" VC, double spider, Maltcross and 3 venting paths for a cool operation, 3 shorting rings, 9mm xmax and 43mm p-p xmech, a resonance reducing surround, and a stiff carbon fiber cone.

The tweeter is an Al/Mg dome with a polymer surround in a thick cast waveguided faceplate, bolted to a cast aluminum chamber. Fs is well damped, and Vance says it does not use ferrofluid. The color of the waveguide appears to be finished compared to the other side being natural as it is closer to a pewter shade.

Feast your eyes...

My interest was sparked when I saw this open source three way project which had two four ohm woofers connected in series to handle the bass.

https://sbacoustics.com/product/tifa-8/

I'm not intending to build it but I just found the concept interesting: why have two four ohm woofers instead of one eight ohm woofer?

The stated dB of the four ohm is 92.5, compared with 90.5 for the eight ohm. The woofers are from the SB Acoustics budget range, SB20pfcr-8 and -4.

From my very basic understanding:

• theoretical dB from the two woofers wired in series would be 92.5
• the cabinet for one woofer could be half the size (VAS is the same for both drivers)
• the two woofer design would move more air, so would suit larger rooms
• two woofers would give you higher power handling
• the crossover would be pretty much the same, with some tweaking to deal with 2dB difference
• I assume that the designer didn't use two eight ohm woofers in parallel - for six more dB - as the mid range would not have sufficient output to match, or for the speaker to present a more benign impedance to the amplifier, as was the case with Curt's "Tritrix" MTM.

Are those assumptions correct, please?

Thank you for your indulgence with what's a pretty basic question

Geoff

Proposed dates are 10/17 or 10/24. We are asking our central Iowa peeps if either weekend works better from a sporting event perspective.

Stay tuned!

And not with the 250 piece minimums anymore!

Spoke to Solen yesterday, Peerless removed the very high minimum order requirements they have had for the past couple of years.

Solen here in Canada will be carrying Peerless again as well.

Good news!

No arguing, either. We are all grown-ups. At least as grown up as people who build speakers for fun can be

I'll start... Mama did a bangup job decorating for Christmas.

New GRS - Replacement drivers for Dynaco A25: 2" dome tweeter and 10" woofer

Already discussed in other threads:
Wavecor cone tweeter
SB Acoustics Satori 7.5" coaxial

I'll probably start with the single woofer version and see how I like the sound.
May move to the ISO version if all sounds good.

Any advice or thoughts other than build it and see?

This first simple jig is just a round scrap of MDF that I cut a cove into that in turn fits a 3-1/2" diameter hole with a 1/2" round over, for recessing terminals. The key is a tight fit, and then drilling the holes square with the plywood, that way I just drop it in, square up the plywood portion with the cabinet and drill. This one has two sets of holes, one set centered and another offset higher.

To round out that driver, in the 'high performance to price style' Zaph was known for: The venerable SEAS 27TBFCG metal dome tweeter, and the Dayton audio RS180P-4. The former was also chosen as a visual match to the ZA14, and the latter mostly because I was impressed with its midbass performance in the Kozo speaker I built some years ago.

It'll be a sealed alignment, rolling off the bottom end at roughly 80 Hz, 2nd order.

I'm doing the crossover model now, and the 3d design for printing the enclosure - a sand-filled double-walled PLA design.

More to come, and given no large issues, I'll have them at Iowa this year to demo.

Going back to a two stacked box build where I can change out the top (broad ranger, coaxial, or mid / tw separates).

I’m now ‘sold’ on sealed woofer(s) so going with a pair of 8in sealed 1.5 way set-up with the .5 rearward facing. Easy enough to incorporate via active, with interchangeable passive top(s).

Top box; while I recently built an ~open back/side Celestion coax, I’m starting with my old friend- an Audio Nirvana Super 6.5. It’s a very solid, cast aluminum framed, broad ranger with excellent extension. So keeping it ‘simple stupid’.

I may down the road try a Markaudio / super tweeter combo (beyma slot or fostex super tweeter) as this image is ‘calling’ me.

I wanted a pair of low-Qcb sealed subwoofers with decent output capability.
And it had to be small. So here it is.
Note: this original idea was snarfed from a big manufacturer with a 3-letter name.

The Build Consists of: 2 x RSS210HO-8's in parallel on a Dayton 250W DSP amp.

The RSS-210HO-8's are mounted on opposite sides of the enclosure.
2x the output and it is vibration cancelling.
This WORKS awesomely, ladies and gentlemen! The sub didn't move on the Telarc 1812 Overture Cannons.
The rig was at -14.5dB on the volume dial. Wendy not home level
This "opposing sides" driver orientation is a highly useful idea and should be seriously considered on a sub build.

Note on Drivers:
I too, prefer the HF's for music but was limited on enclosure size. The HO's fit nicely in a small cabinet, however.
I think the pair will give me a lot of low visibility bass on a large enough scale : )
Won't be Xmaxing a pair of these on music.

Sealed Box Specs:
0.7 Qcb sealed enclosure with Scan Speak AP Vent on the bottom (epoxied in).
Enclosure volume after bracing is 0.68ft3
Fs/F3: 53Hz

I added the AP vent to let the cones do their thing a little more easily and add a little bias towards music.
If your intention is Home Theater or heavy, heavy bass, you may want to leave it out.

I also tried out Acousta-Blue (not really necessary but I can't help myself on damping enclosures).
You can glue it in with Tite-Bond, nice feature.
Also packed with Acousta-Stuf at the end.
T-Nuts are epoxied in.

Cabinet is heavily braced 3/4" MDF with 1.25" Poplar corner blocks c/o Menards.
Additionally, there are a pair of Oak Dowels bracing the enclosure top - bottom.
The weight with drivers and amp makes them little back-breakers.

The second sub's enclosure is complete - just waiting on ordering the drivers and amp.
Opportune moment when the ducats can be apportioned : )

How does it sound? Goes deep deep deep! The 1812 cannons had lots and lots of boom/crunch.
With 2, there will be significant room pressurization.
I used TrueRTA with a calibrated UMIK-1 mic (nice toy) to level up the room.

NAD C.399 XO at 50Hz (18dB/Octave, a little unusual in onboard electronic XO's).
Sub volume to flat and 15 degrees of phase shift - I LOVE this, wish I had it back in the day. Makes dips and peaks go away.
A 3dB touch of parametric at 30Hz to bring the bottom up flat. Nice amp.
Haven't tried the DSP yet other than manual adjustments.

The ZRT's can utterly scream with the bass under 50Hz away and 180WPC from the NAD.
I think I actually got some power compression on the 1812.
RSS builds always seem to turn out well.

Below are pics including Feline Disrespect. As usual.

I

As an example, why would the same driver have such different crossover interpretations?

The two circuits in the attached Xsim diagram are from public domain, three way builds with (I think) pretty much the same crossover points. The top one is paired with a Peerless 830656 mid; the bottom with a Peerless dome mid range and both use the Peerless 830657 as the woofer.

The circuits for the mids and woofers are similar.

Both reportedly sound very good, so does anyone have any comments on why the second XO looks so much more complicated (and expensive)?

Please note that I'm not intending to build either of these - I have something similar in mind from PWRRYD if WAF approval is possible - but I'm still curious

Thank you

Geoff

After modeling just about every configuration and driver 8" and larger, stressing over sealed or vented, actively or passivly boosted, small and large, I finally settled on the RSS390HO-4 paired with the SPA500DSP.

In just over 1 cu.ft. sealed I can get a near flat response down to 20Hz with the DSP functionality of the amp. 500W puts max playback around 102-103 dB anechoic, which I deemed plenty loud enough for my purposes, and I will never run out of xmax, even with DSP room correction/boost. This is a significant upgrade over the W5-1138SMF powered with that old 25W plate amp.

Based on what others have measured in old Inifinity speakers, I was super curious to see how these things did.

My plan was to build boxes for all four (4) drivers and mount them in between the ceiling joists in the roof of my garage/workshop.

I can see myself 3D printing my own ports in the future.

Ron

The first is a Tekton style array. I would have to buy 4 more, but they are on clearance at Madisound currently. This array would have a small format SB Accoustics tweeter in the middle with an 8” below.

The second is a more conventional approach. Again, I was thinking a small format SB Accoustics tweeter in the middle with an 8” below, but in a mmtmmw. I have it drawn as a wmmtmmwww and had thought about using some MAC06 drivers.