RSS315HF-4 as the anchor of a 3-way???

[jkim]

Re: RSS315HF-4 as the anchor of a 3-way???

Pete, this is just a guess, but it's interesting how you got phase perfectly aligned between mid and tweeter with only a 15 dB/oct electrical slope for the mid if the two drivers are time-aligned on the baffle. It might still be possible depending on the drivers' natural rolloffs (w/ the mid slightly off-axis), but I'd double check on the drivers' modeled responses especially at top ends (up to 40 kHz - 50 kHz) for proper rolloffs that were used for HBT phase extraction.

Also, why not LR acoustic 2nd order filters for mid and tweeter if they are time-aligned? The RS28A or F is perfectly suited for this application with its proper Q rolloff, thus having plenty of power handling if crossed at 2.3 k to 2.5 kHz. With respect to linear excursion, it will produce about the same output as the case with your current LR4 filter between 1 k - 2 kHz where the max excursion occurs. This is because any LR2 filter for a tweeter in reality has a slightly steeper slope than the theoretical target below 1 kHz. This still gives excellent phase tracking because of the natural low-end rolloff of any real-world midwoofers---consider how the Duelund 3-way filters work ;). I believe the same filter topology as Zaph used for the XT25 in his ZD5 (single series cap and shunt RL) will work nicely. Impedance flattening LCR may or may not be needed.

[Pete Schumacher]

Re: RSS315HF-4 as the anchor of a 3-way???

I don't know if you can get down to 200Hz without some tube length.

The tube would be a straight shot from behind the mid to the rear baffle, about 20". Is that enough???

[Jeff B.]

Re: RSS315HF-4 as the anchor of a 3-way???

Pot plant?????? :eek:

But in all seriousness, the reason for that shape is more than just looks. The aerodynamic shape will allow the qualities of the drivers to reach the listener with less turbulence and therefore, greater clarity.

Wow, that's brilliant! Why didn't I think of that? :rolleyes:

[Jeff B.]

Re: RSS315HF-4 as the anchor of a 3-way???

Thanks for the tip. Now, the question is what a tube vs a true open back does to the response into the room. I want to use the mid down to the 200Hz XO point. Does the 3dB hold down to that frequency? It seems like a tall order. And I really don't want to push the RSS315 much higher in frequency.

I don't know if you can get down to 200Hz without some tube length.

[Pete Schumacher]

Re: RSS315HF-4 as the anchor of a 3-way???

Scan Speak Revelator 15W for a mid! This is going to be something. I'm not sure if you or other people agree, but after I extensively tested and compared the RS180S-8 and the Usher 8945P with various types of measurements, including my own HD sweeps, and with many filters (including C-E high order filter for the RS180S, recently), I'm now a firm believer of the importance of low tall order harmonics between 500 Hz - 1.5 kHz. I believe that this is because my ear (or our ear?) is very sensitive to the range of 1.5 kHz - 7.5 kHz in which the tall order harmonics arise from fundamentals between 500 Hz - 1.5 kHz.

By the way, I'm now using the 8945P up to 2.3 kHz with a LR acoustic 2nd order filter (w/ a couple of notch filters) and hearing no adverse effects of its 1.2 kHz dip and 3 kHz node on its non-filtered response.

Jay

Yeah, when I was offered a deal on the Scan by DoubleTap, I HAD to figure out a way to get it to play with the RSS315. I'm curious to see how that damped 3rd order approach will work. The transfer function throughout the bass looks real flat by adding the cap.

I will definitely use the Usher in upcoming projects. Paul K's Marcato's were amazing to say the least. He and Dan did a great job integrating the BG tweet into the system.

[Pete Schumacher]

Re: RSS315HF-4 as the anchor of a 3-way???

Just how do you stand a pot plant / photo frame / vase / or whatever dust collecting thing on top of such enclosures ? I cannot see them catching on ! ;)

Pot plant?????? :eek:

But in all seriousness, the reason for that shape is more than just looks. The aerodynamic shape will allow the qualities of the drivers to reach the listener with less turbulence and therefore, greater clarity.

[Pete Schumacher]

Re: RSS315HF-4 as the anchor of a 3-way???

An open back midrange will gain approximately 3dB in sensitivity in the average listening room set-up. You won't be able to pick this up well with measurements either, but your ear will. The increased rear response of the midrange compared to the other two drivers boosts the power response in the midrange's band audibly. I simply found that if I increased the level of my mid's frd file by 3dB my simulations began to match up well with what I was hearing and picking up with an RTA with the mic about 5-6 feet from the speaker. Just a tip.

Thanks for the tip. Now, the question is what a tube vs a true open back does to the response into the room. I want to use the mid down to the 200Hz XO point. Does the 3dB hold down to that frequency? It seems like a tall order. And I really don't want to push the RSS315 much higher in frequency.

[max2tall]

Re: RSS315HF-4 as the anchor of a 3-way???

Just how do you stand a pot plant / photo frame / vase / or whatever dust collecting thing on top of such enclosures ? I cannot see them catching on ! ;)

[Jeff B.]

Re: RSS315HF-4 as the anchor of a 3-way???

I can't believe I didn't think of this earlier.

If I raise the RSS315HF off the floor right next to the mid, around 17", the response in the region above 100Hz begins to drop off. If I adjust the bass alignment, to roll off a bit sooner . . .

The problem is with the XO and its interaction with the woofer impedance peak. The large filter inductor causes a rise in response at resonance that screws up a typical 2nd order filter. Then I thought about Daryl's third order bass alignment.

Voila!!! 3000uF in series with 1 Ohm between the input and the woofer cures the peaking at 60Hz, and along with the baffle diffraction loss by mounting it off the floor, response is smooth and reduced by a couple dB.

It looks like the Revelator and RSS315HF are back in league.

I know, I know, active control. But I'm determined!!!!

An open back midrange will gain approximately 3dB in sensitivity in the average listening room set-up. You won't be able to pick this up well with measurements either, but your ear will. The increased rear response of the midrange compared to the other two drivers boosts the power response in the midrange's band audibly. I simply found that if I increased the level of my mid's frd file by 3dB my simulations began to match up well with what I was hearing and picking up with an RTA with the mic about 5-6 feet from the speaker. Just a tip.

[jkim]

Re: RSS315HF-4 as the anchor of a 3-way???

Scan Speak Revelator 15W for a mid! This is going to be something. I'm not sure if you or other people agree, but after I extensively tested and compared the RS180S-8 and the Usher 8945P with various types of measurements, including my own HD sweeps, and with many filters (including C-E high order filter for the RS180S, recently), I'm now a firm believer of the importance of low tall order harmonics between 500 Hz - 1.5 kHz. I believe that this is because my ear (or our ear?) is very sensitive to the range of 1.5 kHz - 7.5 kHz in which the tall order harmonics arise from fundamentals between 500 Hz - 1.5 kHz.

By the way, I'm now using the 8945P up to 2.3 kHz with a LR acoustic 2nd order filter (w/ a couple of notch filters) and hearing no adverse effects of its 1.2 kHz dip and 3 kHz node on its non-filtered response.

Jay

[Pete Schumacher]

Re: RSS315HF-4 as the anchor of a 3-way???

Pete,

If you go with the scan mid, how about an open back tube? This would allow you to utilize the rear output of the mid to fill in and in a sense, increase its effective sensitivity. Anyway, that was my line of thinking for my project that I mentioned in the other thread. I believe Curt depressed the mids in the Statements about 3db, so you might effectively increase the scans in-room sensitivity by 3db or so, which would make it a better match for the RS315-4. The Scan has plenty of xmax, so this should not push it too hard at the 200hz xover point.

I can't believe I didn't think of this earlier.

If I raise the RSS315HF off the floor right next to the mid, around 17", the response in the region above 100Hz begins to drop off. If I adjust the bass alignment, to roll off a bit sooner . . .

The problem is with the XO and its interaction with the woofer impedance peak. The large filter inductor causes a rise in response at resonance that screws up a typical 2nd order filter. Then I thought about Daryl's third order bass alignment.

Voila!!! 3000uF in series with 1 Ohm between the input and the woofer cures the peaking at 60Hz, and along with the baffle diffraction loss by mounting it off the floor, response is smooth and reduced by a couple dB.

It looks like the Revelator and RSS315HF are back in league.

I know, I know, active control. But I'm determined!!!!

[Pete Schumacher]

Re: RSS315HF-4 as the anchor of a 3-way???

I was thinking that the shape of the current mid enclosure would make an interesting tapered TL. A small slot on 1 side of the peak would do it.

There's no benefit for doing so, since the signal is dropping rapidly below ~150Hz. Having an open back would add some midrange energy into the room.

I've asked the artist if he could squeeze in a PVC tube between the front baffle and rear baffle behind the mid. That way, I can try out the open back option, and if it just doesn't pan out, a plug could be fitted onto the back to seal the chamber.

But I'm really beginning to think that the best option is to change woofers. The RSS315HF-8 should match real well with the Revelator.

[HareBrained]

Re: RSS315HF-4 as the anchor of a 3-way???

Pete,

If you go with the scan mid, how about an open back tube? This would allow you to utilize the rear output of the mid to fill in and in a sense, increase its effective sensitivity. Anyway, that was my line of thinking for my project that I mentioned in the other thread. I believe Curt depressed the mids in the Statements about 3db, so you might effectively increase the scans in-room sensitivity by 3db or so, which would make it a better match for the RS315-4. The Scan has plenty of xmax, so this should not push it too hard at the 200hz xover point.

I was thinking that the shape of the current mid enclosure would make an interesting tapered TL. A small slot on 1 side of the peak would do it.

[Pete Schumacher]

Re: RSS315HF-4 as the anchor of a 3-way???

Pete,

If you go with the scan mid, how about an open back tube? This would allow you to utilize the rear output of the mid to fill in and in a sense, increase its effective sensitivity. Anyway, that was my line of thinking for my project that I mentioned in the other thread. I believe Curt depressed the mids in the Statements about 3db, so you might effectively increase the scans in-room sensitivity by 3db or so, which would make it a better match for the RS315-4. The Scan has plenty of xmax, so this should not push it too hard at the 200hz xover point.

I'll have to think about that one. Putting a tube in there isn't all that difficult, even though the front baffle is angled. I just wonder about all the odd resonances such a tube will introduce into the front, as well as rear acoustic output.

Besides, moving to the RSS315HF-8 isn't a terrible trade off. I lose a little sensitivity, but the impedance gets a bit easier to drive too.

[dlneubec]

Re: RSS315HF-4 as the anchor of a 3-way???

Yes, I did consider the SB drivers. But when the Scans were offered, well, what could I say?

The problem I have now is that the Scans may be a little too low in sensitivity to play with the RSS315HF-4. So, I may have to go with the RSS315HF-8 and drop the sensitivity by 3dB.

Pete,

If you go with the scan mid, how about an open back tube? This would allow you to utilize the rear output of the mid to fill in and in a sense, increase its effective sensitivity. Anyway, that was my line of thinking for my project that I mentioned in the other thread. I believe Curt depressed the mids in the Statements about 3db, so you might effectively increase the scans in-room sensitivity by 3db or so, which would make it a better match for the RS315-4. The Scan has plenty of xmax, so this should not push it too hard at the 200hz xover point.