Tale of two crossovers

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nickd

Tale of two crossovers
« on: 13 Jan 2020, 11:43 pm »
A few months back, I started thinking about a new build. I had been living with Altec Model 14”s and although they were very good, I’m one of those guys always searching for perfection. The Altec “Manta Rey” horn is a dated design and they really need a sub.

When browsing audio sites one evening I read about the new Ellipticor series of drivers from ScanSpeak. In my experience, there are three things that make a great loudspeaker. Fast drivers with little coloration, a properly shaped and inert box, and the heart of any speaker, the crossover.

I could buy drivers, check. Needed an idea for a nice box, pause. I found the Troels Gravensed site on line. Here was a guy after my own heart. Loves loudspeakers! He had a newer design that was shaped a bit like a Thiel or a Vandersteen. Sloped baffle and first order filters. I have a fondness for the old Thiel CS2. Liked the shape, the sound, the crossover, everything. One big issue. They couldn’t play loud without distortion.

After more snooping, I ordered the kit without the Hypex amp and drivers. I had a pair of 12” servo sub drivers in the garage and ordered a couple of PEQ 370 Servo amps from Danny at GR Research. Bought drivers in the USA and hired out the cabinet construction. The Ellipticor drivers are expensive to say the least, but I rationalized the cost by thinking “I’m getting older there will not be many more opportunities to do a fun project like this”.

I have used PBN Audio in San Diego on other custom builds. Over the years he has become one of my very best and trusted friends. He also loves everything audio from his pre-teen years, just like like me. My house and Garage are San Diego small and Pete is a master speaker builder if there ever was one. A few weeks later, they were complete and in my listening room. Beautiful Trans-Red Oak with a Clear coat. Pyramid enclosures made from 1” MDF. Braced to the extreme and with a sloped baffle and rounded corners, a great platform for these “state of the art” drivers.

The sound was not exactly what I expected. I tend to really like ScanSpeak drivers when well implemented. I have owned several speakers with them over the years and enjoyed almost all of them. They are famous for transparency and dynamics. Well, the Ellipticor III was Transparent like an electrostatic, but no real dynamics. Just like a “stat”, The midrange had a noticeable suck-out and the highs were a bit soft and somewhat lifeless. I knew the risk of buying a speaker I had never heard. No hard feelings of Troels, He is a nice guy, knowledgeable and a great builder. This speaker just was not to my taste, and he openly warns of such on his site. Speakers are a bit like people, all different.

Thankfully I also know Danny of GR Research and his famous ability to “make your speakers sound better”. After a phone call, off a speaker was crated shipped to Iowa Park TX from San Diego. Danny measured the speakers and came up with a new filter for the 8”-21WE woofer, 6”- 18WE Mid woofer and the D3404 tweeter.

The new filters and slopes were quite different, but he was happy with the results and sent my speaker home with new crossover parts. Sonicap’s, Mills resistors, Erse Coils, some sweet Miflex bypass caps, new hook up wire and of course tube connectors.

The Holidays slowed my progress, but finally the wire, Tube connectors and crossovers are installed.

The results. In one word. WOW. What a great speaker. Killer Servo sub bass, the transparent yet tone rich mid bass and midrange that great paper drivers produce. The Tweeter. I know what you’re thinking cloth dome tweeters? How 80’s.

This is not your average cloth dome. The Ellipticor D3404/552000 is indeed special. I have lived with the Neo 3 & 8’s and the SB acoustics Beryllium domes, Scan Speak Revelators, etc. They are all very good. The D3404 is at their level, but different of course.

Imaging, tone, transparency, bass slam and control. All must haves at this point in my audio journey. The Ellipticor III with the GR Research crossover has all of those in spades. They are an easy load of mostly 8ohms and over 90db efficient. I use solid state amplification, but with the right tubes I’m sure they would sing just as well.

An interesting journey. I learned a lot, I usually do on these projects. Spending this kind of money on a build is not for the faint of heart. If it doesn’t work out, you scrap it and start over. I find it interesting that this project had 4 designers at different times (not including Scanspeak team or Brian Ding). The result. They are simply breath taking. A unique speaker that will stand with toe to toe with the best of them. Different than some, but excellent at reproducing an emotional musical event.

Thanks Danny, Peter, Troels,
Love my new speakers!

Rusty Jefferson

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Re: Tale of two crossovers
« Reply #1 on: 14 Jan 2020, 12:32 am »
Congratulations on getting the speakers you wanted. Danny does provide an excellent service.  He made crossovers for a speaker project of mine to excellent results also.  :thumb:

Tyson

Re: Tale of two crossovers
« Reply #2 on: 14 Jan 2020, 12:45 am »
Uh, I think we need some pics!

Peter J

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Re: Tale of two crossovers
« Reply #3 on: 14 Jan 2020, 12:49 am »
Uh, I think we need some pics!

Yep, it's mandatory. Don't be a woodworking tease!

Danny Richie

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Re: Tale of two crossovers
« Reply #4 on: 14 Jan 2020, 04:05 am »
I think one of his speakers made it into one of my Tuesday Tech Talks.

And yes, very nice speakers. I liked them.

nickd

Re: Tale of two crossovers
« Reply #5 on: 14 Jan 2020, 05:14 am »



nickd

Re: Tale of two crossovers
« Reply #6 on: 14 Jan 2020, 05:16 am »



maty

Re: Tale of two crossovers
« Reply #7 on: 14 Jan 2020, 08:25 am »
Ellipticor-3



http://www.troelsgravesen.dk/Ellipticor-3.htm


by Troels Gravessen



5 components




by Danny Richie

18 components



Quote
The results. In one word. WOW. What a great speaker...

Imaging, tone, transparency, bass slam and control. All must haves at this point in my audio journey. The Ellipticor III with the GR Research crossover has all of those in spades. They are an easy load of mostly 8ohms and over 90db efficient. I use solid state amplification, but with the right tubes I’m sure they would sing just as well...

poseidonsvoice

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Re: Tale of two crossovers
« Reply #8 on: 14 Jan 2020, 12:04 pm »
Oh I see.

http://www.troelsgravesen.dk/Ellipticor-3.htm

It’s important to put all this into perspective (for my small brain!).

The goal of Troels here was a 1st order crossover, which might be doomed for failure without compensation circuits and the like. No measurements of step response etc were revealed...to prove his goal was met. A higher order crossover will most likely help and there you have it. That being said, even after listening to Dunlavy, Vandersteen, ie true 1st order designs by competent engineers, my impressions are somewhat “meh”, not bad, but so much effort for what can already be obtained with other higher order crossover designs. 1st order designs are actually tough to get right. Like Nick said, at higher SPLs, a lot of 1st order designs, sadly, fall apart, even when the drivers are intrinsically uber smooth outside of their pass band. And most if not all, are somewhat inefficient. The best examples I have heard are from Vandersteen and he exerted herculean efforts to get the drivers to “behave.” It gets expensive and in my opinion it is an antiquated method of designing.

This thread would be demonstrably more instructional if before and after measurements were posted (from Danny’s archive), not just a potpourri of crossover parts pictures! In addition, showing us HOW the measurements were done in particular, how a reflection free area was developed to establish some honesty to the measurements. I am very much afraid of looking at measurements that have too much gating or smoothing as it substantially decreases the resolution of said measurement in order to make the graph look 'pretty.' It's the reason why anechoic chambers exist and the Klippel NFS speaker measurement system exists as well.

Thank you!

Anand.
« Last Edit: 14 Jan 2020, 02:06 pm by poseidonsvoice »

Danny Richie

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Re: Tale of two crossovers
« Reply #9 on: 14 Jan 2020, 01:39 pm »
Matty, unfortunately that is not how the speaker measured with that network.


maty

Re: Tale of two crossovers
« Reply #10 on: 14 Jan 2020, 01:52 pm »
Being the original filter so simple it does not seem logical that the cause of the discrepancy is its implementation. I suppose the tweeter has been inverted (like my modded little coaxials) as indicated:




https://www.google.com/search?q=ellipticor+3

-> http://www.troelsgravesen.dk/Ellipticor-3.htm

-> http://www.jantzen-audio.com/ellipticor3/

-> https://www.audiocircle.com/index.php?topic=165022.0

-> https://www.diyaudio.com/forums/multi-way/330903-troels-sine-cap.html


-> https://audioxpress.com/article/test-bench-the-new-ellipticor-d3404-552000-tweeter-from-scan-speak



Quote
Figure 3: Scan-Speak Ellipticor D3404/552000 horizontal on- and off-axis frequency response (0° = black; 15° = blue; 30° = green; 45° = purple).

I can not bring more light than its owner, Peter Noerbaek and Troels Gravesen.

nickd

Re: Tale of two crossovers
« Reply #11 on: 14 Jan 2020, 03:05 pm »
Marty,
For Clarity, Troles is the primary designer of the upper cabinet chambers, cabinet shape, baffles etc. Troles also designed the 1st order filter included in the kit.

Peter Noerbaek built the cabinets and modified the lower sub section to have the correct volume for the sealed 12” GR/Rythmik servo sub. The back panel also has to be modified to house the PEQ370 amp.

Pete frowned upon my selection of a 1st order design. He is not typically a fan. It was a bit of an I told you so moment when we first hooked them up.

Like I said, they weren’t bad, just not to my taste. There are audiophiles who enjoy a mid range dip and limited dynamics. Just not my preferred sound. It was a very “warm” sounding speaker in kit form.

Anand,
I don’t believe Danny uses a built anechoic chamber. That said his method is sound and his results speak for them selves. I sent the speaker to Danny because I’m my opinion, his methods, filters and parts selection produce designs I enjoy listening to. This speaker is astonishing is resolution. But yet smooth as butter.
A computer optimized anechoic chamber validated crossover just does not light my fire any more. I have owned at least 40 of them. They typically sound hard and lifeless.

Like I said speakers are different. Just like people. Some are joyful, some are painful. Means of measuring is a bit of an art form as much as science.   
« Last Edit: 14 Jan 2020, 04:06 pm by nickd »

maty

Re: Tale of two crossovers
« Reply #12 on: 14 Jan 2020, 03:29 pm »
The changes you comment on refer only to the active subwoofer, so the response should be similar in counting from 200 - 300 Hz. It would not be the first time someone incorrectly connects the tweeters, DIY or not.

If you look at the woofer(s) curve, I think the logical thing was a second order filter for him. And then the tweeter without inverting. Bypassing the tweeter cap with Miflex KPCU-01 0.022uF and Miflex MRA12 (12 watts) as resistors, my choice.

Or something like Zvu proposed to KEF Q100 (two first order).

[IMG, link] http://maty.galeon.com/WP-imagenes/kef-q100/KEF-Q100-fabricka-zvu.png

[IMG, link] http://maty.galeon.com/WP-imagenes/kef-q100/KEF-Q100-modifikovana-zvu.png


poseidonsvoice

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Re: Tale of two crossovers
« Reply #13 on: 14 Jan 2020, 03:55 pm »
Nick,

Thanks for your opinion and sharing your project. It is an enjoyable read. I would like Danny to share more of his methods and changes to the original design when he has time. Academic for me, if that makes sense. Oh and just to clarify, I am not talking about computer optimized crossovers, etc...that is a different topic in and of itself.

Best,
Anand.

nickd

Re: Tale of two crossovers
« Reply #14 on: 14 Jan 2020, 04:27 pm »
Maty,
we tried the tweeter with both polarity. While one was better than the other. Still not exactly to my taste. I'm pretty sure Danny measured with the tweeter in both polarity also, as we sent the speaker with bare wires for easy hookup. Like I said they measure in kit form how a lot of people like their sound. Not bad per say, just different. People used to love the Cary 805 Tube amps. They would make a thin sounding speaker sound much warmer. The 805 added a bit of "Fletcher Munson Curve". to the sound. My amp is accurate. Therefore I need a speaker that has a pretty flat response through the lower mids and upper presence range.

Danny Richie

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Re: Tale of two crossovers
« Reply #15 on: 14 Jan 2020, 04:56 pm »
If you guys want to learn about the crossover designs and how they function than I can post before and after measurements, but only if it is okay with Nick. I did this work for him.

nickd

Re: Tale of two crossovers
« Reply #16 on: 14 Jan 2020, 09:23 pm »
Danny,
I don’t have any issue with folks seeing your work and or measurements. The mid range response is a bit of a bragging right.  :thumb:

poseidonsvoice

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Re: Tale of two crossovers
« Reply #17 on: 15 Jan 2020, 02:14 am »
Danny,
I don’t have any issue with folks seeing your work and or measurements. The mid range response is a bit of a bragging right.  :thumb:

Looking forward to it  :thumb:

Best,
Anand.

jmpsmash

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Re: Tale of two crossovers
« Reply #18 on: 15 Jan 2020, 02:39 am »
I like how in Danny's crossover he measures and marks the actual value of the components. Not practical at our hobbyists quantities but for him with benefit of scale it allows better matching.

poseidonsvoice

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Re: Tale of two crossovers
« Reply #19 on: 15 Jan 2020, 02:49 am »
I like how in Danny's crossover he measures and marks the actual value of the components. Not practical at our hobbyists quantities but for him with benefit of scale it allows better matching.

Indeed! Not just that, but I have (more than once) measured a cap/resistor/inductor that is labeled “X” from the manufacturer and actually measures as “Y.” With a calibrated LCR it’s very possible to verify these things and get it right the first time. And more importantly if you don’t then your troubleshooting forever! Sure it’s an issue with a crossover (and easily fixed if so), but imagine a complicated diy SMD based amp, then what? You end up scrapping the project!

Best,
Anand.