If you're headed down that path, it looks like Joseph Crowe offers 3D CAD files for that horn... maybe try that?
3D CAD Model for Horn No.1155 —- Biradial for RAAL 7020XR – Joseph Crowe
3D CAD Model for Horn No.1155 —- Biradial for RAAL 7020XR – Joseph Crowe
One could do much better IMO. The beamwidth of that horn is already 120° at 5500Hz. I think a more narrow beamwidth (90° is a personal preference) with pattern control down to c 2500Hz would be a better match for the Purifi.
Perhaps an elliptical throat would help reduce cancellation nulls vs the parallel walls of your tractrix horn. Just spitballing.
Perhaps an elliptical throat would help reduce cancellation nulls vs the parallel walls of your tractrix horn. Just spitballing.
Well, I’m going to listen to it on flat baffle with the TL for a while. I like how it sounds so far on a plain baffle and can’t wait to hear it with the full TL for bass. The crossover is certainly simple. Not sure how much the 3kHz peak will bother people. Thinking it’s probably from the sharp edges baffle.
This is a great project. I have early edition Selah Audio Veritas monitors (RAAL 70-20XR with SB Acoustic midwoofer ( not the final Seas driver chosen)) and feel the box holds back their potential. A TL design would be a great option to try. I have been very curious about the PTT6.5 since you first posted about it. Looking forward to seeing how this all evolves.
.. dB
.. dB
Hi Dbel84,
That’s nice to see other folks on DIYA who own one. I can’t wait to get the TL box back to test it out further. Debating whether or not I should go ahead and assemble a stereo OB pair. The imaging might just be killer and seal the deal. 😎
That’s nice to see other folks on DIYA who own one. I can’t wait to get the TL box back to test it out further. Debating whether or not I should go ahead and assemble a stereo OB pair. The imaging might just be killer and seal the deal. 😎
After more careful reading I see that this waveguide needs to have the face plate of the RAAL removed. That will destroy the factory set pre-tension on the ribbon and make it flap like flag in the breeze. One would need make a faceplate replacement that clamps the ribbon and allows tightening of the clamp after the ribbon tension is set with a hot air gun. I think a design that keeps the factory faceplate would be essential for making this work. But as I have found out - the requires the waveguide to start after the faceplate - preventing a smooth transition from ribbon to horn. Also, not having a screen mesh guard is asking for trouble. That magnet will suck objects right down the bore like a black hole funnel. The mesh is the only thing to keep such things from happening.
YouTube
That is too much trouble to get a waveguide installed on the 70-20XR.
I also don't see a reason to use a waveguide on the 70-20XR with your current PTT6.5 setup:
- your XO point is at 3.5Khz, you don't need the extra output of the waveguide
- the 70-20XR should be used above 3Kz, below is too much distortion
- the great accidental XO will be not so great anymore 😉
Yes those magnets are very strong, I've discovered that when a screw and my screwdriver was pulled to it, lucky there is that mesh.
I also don't see a reason to use a waveguide on the 70-20XR with your current PTT6.5 setup:
- your XO point is at 3.5Khz, you don't need the extra output of the waveguide
- the 70-20XR should be used above 3Kz, below is too much distortion
- the great accidental XO will be not so great anymore 😉
Yes those magnets are very strong, I've discovered that when a screw and my screwdriver was pulled to it, lucky there is that mesh.
Viawave looks super and perhaps perfect here as well. I just don’t have one on hand - unless someone wants to loan/gift me one for a measurement and new XO development.
well worth trying OB - here is an experimental OB system I tried - still need to go back and tweak as the XO was far from optimal. I bought a DSP4X10 to help model the ideal XO but haven't set it all up again to make it happen. I have also since bought a small horn to play with as an alternative to the RAAL
- if only we could be content with a single set up
..dB
dB, that’s a sweet setup! Lowther DX4?
Reminds me a bit of my one time fun with a big OB that had all high sensitivity drivers. A CD horn, dual 95dB 5MR450NDYs and dual Beta 12cx used as woofers.
So it looks like you have already removed the RAALs from their original box?
Reminds me a bit of my one time fun with a big OB that had all high sensitivity drivers. A CD horn, dual 95dB 5MR450NDYs and dual Beta 12cx used as woofers.
So it looks like you have already removed the RAALs from their original box?
The RAALs are back in their original box but I don't use the monitors much. My daily drivers are Maggies. The fullrange in the OB is the driver from the Moth Audio Cicada (I thought the original towers limited this driver too).
OBs are such fun and I feel that they provide some of the most realistic acoustics (the same reason I like TLs )
OBs are such fun and I feel that they provide some of the most realistic acoustics (the same reason I like TLs )
Added a Miflex KPCU-01 0.1uF 600v paper/PP/oil cap bypass on the 2.2uF RAAL tweeter cap. Listening now - subtle but nice improvement in detail over a no-name 2.2uF film cap. A RAAL definitely deserves the best caps you can afford.
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Only a bit? Try with Hotel California (Eagles). In my small coaxial the difference between the two loudspeakers was overwhelming.
Maybe the RAAL tweeter is not so good 😛
Maybe the RAAL tweeter is not so good 😛
That red no-name cap looks very much like Chinese "Audiophiler" caps that are the worst sounding PP caps I have ever encountered. They were sonically behind even MKT block caps in my comparison. Miles under Miflex league anyway...
Those are temporary development kit caps. I have a set of Clarity 2.2uF 630v CMR caps on the way - should be here soon. The red Chinese caps work for temp duties - they were ranked a 7 out of 15 by Humble Homemade HiFi:
Humble Homemade Hifi - Cap Test
These are the new Clarity that are on order:
ClarityCap Capacitor 2.2uF 630Vdc CMR Series
Bypass caps have different effects in different crossovers and systems. In your case, it is for a KEF 1st order filter in a coaxial, here it is a 2nd order filter and at a different frequency and with a riboon vs a dome. Lots of different things at play. A RAAL certainly sounds better than any dome tweeter I have heard from a standpoint of resolution transient effects.
Humble Homemade Hifi - Cap Test
These are the new Clarity that are on order:
ClarityCap Capacitor 2.2uF 630Vdc CMR Series
Bypass caps have different effects in different crossovers and systems. In your case, it is for a KEF 1st order filter in a coaxial, here it is a 2nd order filter and at a different frequency and with a riboon vs a dome. Lots of different things at play. A RAAL certainly sounds better than any dome tweeter I have heard from a standpoint of resolution transient effects.
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Logically, fewer components needed in the filter, more the differences in the quality of the components, if any, should be noticed. So I am resisting increasing the complexity of the KEF Q100 crossover, maybe the woofer section.
I do not remember reading a bad comment about the RAAL ribbon tweeter except for its high price. They all speak wonders.
I do not remember reading a bad comment about the RAAL ribbon tweeter except for its high price. They all speak wonders.
"The red Chinese caps work for temp duties - they were ranked a 7 out of 15 by Humble Homemade HiFi:
Humble Homemade Hifi - Cap Test"
I know 😉 I was shocked to see 7 there... my guess is that their production QC varies and I got a real bad batch. Good thing you got Claritycaps
Humble Homemade Hifi - Cap Test"
I know 😉 I was shocked to see 7 there... my guess is that their production QC varies and I got a real bad batch. Good thing you got Claritycaps
As I am an electronic illiterate can you give me the value in ohms of your resistors in your crossover diagram/ schematic ...ie 510m=?
510 milliOhm or 0.51ohm
Please not that these are open baffle measurements and the final closed box TL sensitivities will be different. I expect some higher value resistor to be required to balance the treble with the bass better.
Open baffle will sound louder than in a box for frequencies above baffle step.
Please not that these are open baffle measurements and the final closed box TL sensitivities will be different. I expect some higher value resistor to be required to balance the treble with the bass better.
Open baffle will sound louder than in a box for frequencies above baffle step.
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