So after loving my original SSE for a couple of years I kept eyeing my 2 way horn speakers that use active crossovers and wished I had four channels of single ended tube to drive them. With the amount of times I tinkered with my original SSE I was very comfortable with it and figured I’d just make another one and they could live together with the horns.
First issue was my original used 5k/8 OPTs and the woofers in the horns are 4ohm, that was pretty simple to get around, just ordered a pair of matching 5k/4’s along with another xpwr222 from edcor.
That sorted, then came battling with my internal need for symmetry and aesthetics, so I spent probably a bit too much time figuring out the smallest possible footprint where I could reasonably mirror the chassis and settled on what’s shown below. The choke is horizontal underneath the PT as the feedback from folks on here a few months ago was to keep it as far from the OPTs as possible. Used a water jet to cut the panels and used simple bends and walnut caps to tidy things up. Finally a pair of mono pots so each driver could be tweaked once it’s set up.
I’m super happy with how they turned out, it was my first endeavour with sheet metal based cad so it was a learning experience that thankfully worked out.
Now I just finished putting them together and it’s too late to hook them up, so listening impressions tomorrow.
First issue was my original used 5k/8 OPTs and the woofers in the horns are 4ohm, that was pretty simple to get around, just ordered a pair of matching 5k/4’s along with another xpwr222 from edcor.
That sorted, then came battling with my internal need for symmetry and aesthetics, so I spent probably a bit too much time figuring out the smallest possible footprint where I could reasonably mirror the chassis and settled on what’s shown below. The choke is horizontal underneath the PT as the feedback from folks on here a few months ago was to keep it as far from the OPTs as possible. Used a water jet to cut the panels and used simple bends and walnut caps to tidy things up. Finally a pair of mono pots so each driver could be tweaked once it’s set up.
I’m super happy with how they turned out, it was my first endeavour with sheet metal based cad so it was a learning experience that thankfully worked out.
Now I just finished putting them together and it’s too late to hook them up, so listening impressions tomorrow.
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Initial listening tests are very very positive, turns out 10W or so is more than you would ever ever need on 115dB compression drivers or a 105dB mid bass bin. Especially with no passives I’m the way sucking up any power.
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Congratulations! Looks great! Nice symmetry!
Impressive water cutting of the sheet metal and bending into a chassis. Was that commercially done or did you have access to the equipment? Could you tell a bit more?
Impressive water cutting of the sheet metal and bending into a chassis. Was that commercially done or did you have access to the equipment? Could you tell a bit more?
Thank you! As for the cutting/bending I'm doing a master's degree in engineering and while my research is all augmented reality based we have some very nice facilities we can occasionally make use of when things are slow (with our own materials obviously). I designed the chassis in solidworks, cutouts were all based on datasheets for the parts since I designed it before a few things showed up (which is always terrifying). I made some models of the bits that were going into the chassis so I could fit it together as an assembly before sending anything to the waterjet though, shown below. Bend radius and tolerances were all based on 18ga mild steel so it was a breeze once it was ready to bend. Did those on a pretty simple bending brake with adjustable dies, but I had made the design specifically to be pretty easy to bend without anything too fancy or exact.
The symmetry thing, while a great idea on paper presented some annoying issues with wiring it but it all went find and there's zero hum, the one that has the output transformers opposite the output side of the pcb I braided the wire and the other one has the heater supply crossing the board so that one I used a fairly tight twisted pair in a kevlar jacket just in case it gets toasty, not touching anything but close enough to be a little nerve wracking.
For the signal wires everything is cat 6 cable and with the two unused pairs snipped off, gotta love pre-twisted, shielded copper that's readily available.
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Do you find the NS1000 image better that way, i would by default, put the tweeter/mid on the inside.
Nice job on the SSE. 2 oupput tubes/channel?
dave
Nice job on the SSE. 2 oupput tubes/channel?
dave
Haven't modified the SSE design at all really, I assume the kt-120's will just last 3 times as long as 88's doing the same work, cathode resistor is 560 ohms and the xpwr222 is a 375-0-375 350mA transformer, doesn't even get much more than cozy warm after a few hours of heavy use. As I'm learning a bit more about tube circuits I'm tempted to screw around with it more but for now they're doing their job.
Oh and the big horns cross at 500Hz, the opt's frequency response is down to 40Hz and the lascala clone bass bins can't do much of anything below 50Hz so it works well, the active crossover send everything below 60Hz to the subwoofer with the appropriate delay to keep from being a mess with the folded horns.
I find I prefer the 1000's like this mostly because of the limitations of the room, getting a little distance between them helps with the imaging, they're probably the most sensitive speakers I've ever owned as far as placement is concerned (including magnepans). They go from magic to "kinda ****" pretty fast if they aren't in the right spot, I'm sure tons of people with harsh opinions about ns1000's just heard them in the wrong room.
And yep, the sse is feeding the big horns that are active crossover fed, so 1 tube per driver per channel.