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Get familiar with the reaction system: Introducing the Reaction System
NLA Project #11 in Walnut
I started 5 pairs of speakers using NLA Peerless 5 1/4" Nomex buyouts in 2018 and finally finished up the 4th pair. This pair used the SB Acoustics SB29RDC-C000-4 tweeter. I didn't do a lot of documenting this build since it's nearly identical to previous NLA projects which most of you have seen. I delivered them today as a birthday present to my sister-in-law and her husband and she was thrilled.
Now I need to find something for them to power them with. Seems like the entry level for anything with digital optical in is $300.
Ron
Comments
Very nice, as usual! I still have a few of those woofers hiding somewhere in my stash. I'll put them use eventually.
Are you looking for a receiver or integrated amp? Would a little Class D amp be enough for them? There are a few on Amazon with optical inputs, like the SMSL Q5.
That might just work.
Ron
Those look great Ron!
A lot of the little Class D amps have optical inputs. I recently bought a Fosi DA-2120C for my inlaws to power some 5" Silver Flute 2 ways that I built for them a decade ago. I tested it out before I gave it to them and I was really impressed with it.
both the SMSL and the FOSI seems to be in the 150$ mark. need to try one
I've used an SMSL Q5 for everyday listening in my theater room for a couple of years. I switch out speakers frequently by mood or for tweaking and I love that little thing.
Great job again, Ron.
Man oh man, that's a super flat response! Beautiful, clean wood working as usual.
Hi Ron. Cool project and great looking speakers as usual.
First question: I see that you used a 4th order electrical filter plus a bottomless notch using the first inductor with a small cap for the woofer. Was there something nasty about the woofer that demanded it or did you just want to cross the woofer over low with a steep slope? I'm guessing that is a very robust tweeter that can cross pretty low with a steep slope.
Second question: On your schematic diagram for the crossover the woofer and tweeter's x,y,z positions are identical but only the Z axis is zero. I assume SoundEasy being a two channel measurement system takes the time of flight (Z axis) into account. But what about the X and Y values? Listening position higher/lower and speakers not toe'd in?
Thanks.
It's been quite a while since I designed this crossover so I'm not exactly sure why I put the cap across the inductor in this case. I use the filter optimizer in SoundEasy for all my designs. You start with a filter of your own or one that SE will design for you. You pick the response you want to end up with and you tell SE the range you want to optimize along with the parts you want SE to work with and it will try to come up with a response curve that matches the response you chose. It will also give you a numeric value for how close you came. Somewhere along the line I learned that you can put a small value cap across the 1st inductor in a low pass filter and you can alter the response of the low pass to either suppress breakup modes or improve the slope of the filter to match the target. It's usually a small value cap so I don't mind using it for even a minor improvement.
You are correct that SE takes into account time of flight. You take the tweeter measurements on axis with the tweeter and without changing anything you take the woofer measurements. You need to do a Hilbert-Bode transform on the response measurements and adjust the tails of the transform response measurement until the transform phase matches the actual measurement phase. When you do the transform on the woofer response you can adjust for distance. This is the actual transform for this woofer.
As part of the woofer measurement process SE has you simulate the baffle response and that gets added to the summed NF and port measurements. You then splice that to the FF measurement. The simulation lets you create the baffle and place the various drivers on it at which time you get to choose the mike location. In this case I chose the tweeter axis. I have no idea where the x,y,z coordinates come from in the crossover schematic. They're just part of the 1000's of boxes, options, and obscure elements in SE that keep most people so confused that they never use it.
Ron
Thanks for all the compliments and advice on amps. My sister in law ordered one of these which should work just fine.
https://amazon.com/Bluetooth-Amplifier-Integrated-Converter-Streaming/dp/B07K7MYTXX?th=1
Ron
Great choice. That's the one that I got for my inlaws and I loved it.
I bough the little Fosi 2 channel amp and I was surprised it took about 2 weeks for the amp/ caps to charge/ melo out