Exploring Purifi Woofer Speaker Builds

[xrk971]

I see that the new Jones-Scanlon Baby Reds (approx $4400 USD, per pair) are based om PTT6.5 together with tweeter Faital Pro FD371.
Would Harsch XO be applicable to the FD371?

RAAL is seriously very good.
We used them (AG-version) in our "Bendit" Project.
Why is 4th order for RAAL compulsory ? (4th order is a recommendation for 1600 hz). I guess you are aiming for low xo avoiding beaming from PTT?

I am getting an extra set of baffles made for the PTT6.5 TL to allow mounting of a RAAL 70-20xr ribbon. It should be a simple LR4 XO with the RAAL in reverse polarity.

 

[5th element]

Put the RAAL in a waveguide! I mean for all the hype the ribbon isn't that happy below 3kHz. Hopefully with the WG loading, and necessary filter to achieve a flat response, it would allow it to cross lower and have a good directivity match with the Purifi.

 

[xrk971]

The RAAL 70-20xr is supposed to be able to go down to 1600Hz according to factory data sheet. I agree a WG would be the cat’s meow but would require me to design one and 3D print it. I have made a foam core tractrix for it and had some issues with cancellation dips due to the sharp 90deg sidewalls. I suspect a shallow angle WG would be less likely to have those problems.

Nano-Trynergy - a Compact Tractrix RAAL Ribbon Point-Source Horn

Here is a quick attempt at 3 way with parallel sealed RS225-8 woofers and dual (highly attenuated) 3FE22-8 mids at injection ports.

 

[5th element]

Yeah RAALs claims are more than a bit optimistic. The tweeter might not suffer damage when used that low but HD rises rapidly below 3k especially the high orders.

Measurements are here

RAAL 70-20XR | HiFiCompass

Note that this is even with a 4th order at 2k in place. They definitely can't be used down to 1.6k unless you like listening to distortion or only listen very quietly. I'm sure things look a lot better if they are only producing 70-80dB.

 

[xrk971]

Maybe I should stick with 3500khz crossover - that would be easy as that’s where my current XO is located. The polars won’t look as good as with the RS28F in a WG300 though.

 

[soundchaser]

Hi jmpsmash;

I mean no disrespect but seeing the cable routed in through the port made me laugh my head off! That is a very practical approach.

Cheers
Matt

6.5 cu ft. it takes up quite a bit of space!

 

[wilbur-x]

There is a Seos WG that fits to Raal 140-15D, would that be convenient?
Not so serious:
An extra "k" may have sneaked into the above xo ;-)
The second port do miss a cable for cat stop.

 

[Skip Pack]

I am not sure EQ’ng the PTT6.5 to get stuff above 3.5k makes sense. It’s a midwoofer. I would consider pairing it with a Scanspeak 10F. That might be very nice sounding. Cross around 1kHz.

I would think your TL cabinet would work well upside down with the 10F in an exposed penta-dagger above the Purifi, using your 1st order crossover. Would the driver centers be too far apart?

Skip

 

[xrk971]

Or a Dagger with 10F properly mounted in the baffle. I will try the RAAL first then cut the hole bigger for a 10F and small rear chamber.

 

[jmpsmash]

Hi jmpsmash;

I mean no disrespect but seeing the cable routed in through the port made me laugh my head off! That is a very practical approach.

Cheers
Matt

It is work in progress... for the past 10 months.

 

[jasdiy]

I tried crossing at 80Hz and then 120Hz. 120Hz has more grunt to the bass.

Can I ask what the filter slopes were.

 

[Mooly]

Some posts from MaikelM and following replies have been deleted due to personal issues.

Hope all works out OK

 

[xrk971]

My TL build is almost done. I even have a spare set of baffles for the RAAL 70-20xr made up:

 

[Norman Tracy]

Shiny. So shiny for MDF. XRLaudio will soon be having the Big Fun Time.

 

[5th element]

That's not MDF he's using plywood for the cabinets.

It'll be interesting to see what you think of the TL vs PRs.

 

[xrk971]

That’s 3/4in BB plywood on exterior panels and 1/2in BB on interior walls. The templates for routing the holes was made of MDF - so that may have caused some confusion. I have a super experienced cabinet maker doing these for me as I don’t have a wood shop nor the skills to make fine joints like this. He tells me they will be delivered tomorrow in the PM. I will still need to install final stuffing, crossovers, and general buttoning up. Will be using square drive socket cap screws to secure the baffle. Should look great.

Here is a template:

 

[nicoch58]

great project

 

[Norman Tracy]

It's ironic I mistook XRK's Birch ply for MDF. I am a big proponent of quality plywoods over MDF. Let's leave the MDF vs. BB discussions to the other 214 threads online where that has been discussed. I'll just say I prefer working with BB.

 

[xrk971]

Only 3 hrs more to go before I take delivery!

Side panels getting glued on and front baffle screw holes getting drilled out.

The proportions look pleasing to me so far. I hope it is not too heavy to lift onto a tall speaker stand.

 

[ScottG]

I always loved the "Phil Jones" chuncky, square & squat, deep, stand-mounted monitor school of aesthetic.

Now you just need to grab the AE2's double-column stand!