Building field coil speakers Rullit Aero

[Lautreamont]

My pleasure, Lautreamont!

Yes, you're correct. The Qts parameter of the driver changes value with voltage, which may allow for use in different applications. Low voltage results in high Qts, which can work for a sealed enclosure, or open baffle design. Conversely, high voltage lowers Qts, which may work well for a ported enclosure. Of course, there are always trade-offs. Lowering voltage for a high Qts comes at the cost of sensitivity.

This is very satisfying and good news - thank you very much. I appreciate all the informative posts on this forum - I learn something new every day.

I will try to investigate the matter more in the coming time and then come with a conclusion. It seems that there's a hope that I can find a cabinet that brings the best out of the Rullit and then match it with a single ended amplifier that produces enough power to tame the "beast" of the field coil while ensuring that there is room enough in my apartment.

 

[Treehaus Audiolab]

Thanks for the shout-out Ken!

Lautremont,
I make complete speakers using the Rullit Aero or Super Aero. In my experience with them, I have found them best suited in more of an open-baffle design. I experimented with open-backed boxes (along with a myriad of other variants) but I did not personally like the color they introduced. I did also find that in an open baffle, the 10" drivers start to roll off perhaps around 90-80hz (its a rather gentle roll-off) and the 8" is probably around 120-130hz (its open baffle, and field coil, so there are a lot of other variables at play) I could enjoy them without any bass augmentation, but they do require a low woofer to complete the sonic picture.

I recommend for our speakers 2ft from the face to the back wall as a minimum, with 3ft+ being preferred.

@TKK has my speakers in his apartment space, he might be able to chime in a bit as well as to how they perform in such environments.

 

[dcathro]

Thanks for the shout-out Ken!

Lautremont,
I make complete speakers using the Rullit Aero or Super Aero. In my experience with them, I have found them best suited in more of an open-baffle design. I experimented with open-backed boxes (along with a myriad of other variants) but I did not personally like the color they introduced. I did also find that in an open baffle, the 10" drivers start to roll off perhaps around 90-80hz (its a rather gentle roll-off) and the 8" is probably around 120-130hz (its open baffle, and field coil, so there are a lot of other variables at play) I could enjoy them without any bass augmentation, but they do require a low woofer to complete the sonic picture.

I recommend for our speakers 2ft from the face to the back wall as a minimum, with 3ft+ being preferred.

@TKK has my speakers in his apartment space, he might be able to chime in a bit as well as to how they perform in such environments.

Hi Rich,

I am curious, at what frequency do your woofer start to roll off in the open baffle?

I know people worry about overloading small rooms, but I have 15" field coils in 130L ported boxes (tuned to 35hz) with open baffle wideband (170 - 6khz) in a small 15 meter sq room. I have the speakers (acoustic center) 3' from the front wall, but the speakers close to the side walls to get bass re-enforcement.

By the way, it is great that you and Ken interact with the DIY guys and give advice. It really does elevate this forum in my opinion!

 

[Lautreamont]

Thanks for the shout-out Ken!

Lautremont,
I make complete speakers using the Rullit Aero or Super Aero. In my experience with them, I have found them best suited in more of an open-baffle design. I experimented with open-backed boxes (along with a myriad of other variants) but I did not personally like the color they introduced. I did also find that in an open baffle, the 10" drivers start to roll off perhaps around 90-80hz (its a rather gentle roll-off) and the 8" is probably around 120-130hz (its open baffle, and field coil, so there are a lot of other variables at play) I could enjoy them without any bass augmentation, but they do require a low woofer to complete the sonic picture.

I recommend for our speakers 2ft from the face to the back wall as a minimum, with 3ft+ being preferred.

@TKK has my speakers in his apartment space, he might be able to chime in a bit as well as to how they perform in such environments.

Thank you very much for sharing your experience. I agree with @dcathro - it is truly amazing that you take your time to visit these forums and share your thoughts. It shows great and genuine character.

I have seen videos of people using the field coil driver as the only single unit but it also makes sense with a woofer. I think the choice of enclosure will probably deduce if I need a bass solution.

I hope TKK will find his way to this thread and share his experiences as well - I hope that a lot of people can learn from this thread.