Something Stirs in the Workshop

[vinylnvalves]

Followed the instructions off Brian Steeles subwoofer site on time alignment, changing to an (MSL)modified square wave input signal without much success. I seem to get too much noise on the bass/mid driver signal to really distinguish the phase and time of the impulse signal. Will have try REW to see if it gives me a different answer.

I might have call on the services of Dronfield Acoustics……..

[brig001]

Just had another look at the blue trace, and there's a lot of HF there for a sub
Is the brown (?) line the sub or the blue one? There's not much difference time wise, but just to be sure
Did you test with the crossover bypassed?

Sorry for all the questions, but it doesn't look right - then again, I haven't used Holmimpulse

Brian

[vinylnvalves]

The blue one is the 30hz to 120hz range, it’s a 2nd order LR crossover, not the higher order i mistakenly quoted before. There isn’t any HF output that I can hear. The measurement are all indoor, so the room contributes too.

[vinylnvalves]

Just finished the test horn, shipping it out for evaluation. Bit trickier than first thought as had to recontour the inner after a late change in throat angle, plastic wood filler to make the inner match, as cannot add wood. Not my finest work, as cobbled together out of the firewood box, and glued out of lots of bits
(Also trimmed 5mm off the width to make it fit in a box ). It sims a lot better than those ES horns I built before. It’s 395x 320mm. Slightly truncated as that was the biggest piece of scrap I had lying about.
4170169D-8286-45F3-8331-412CB41FDFD9.jpeg

Got some measurements back for the horn, with the SB 65Cdnt driver fitted. Almost as simulated, shame about the driver breakup at 15khz

rossi trace.JPG (71 KiB) Viewed 35906 times

[chris661]

Yep, medium/large-format HF drivers will do that. I have some 18Sound ND1460 which are similar. At PA levels, though, nobody seems to mind too much. The high-Q peaks and dips would be very difficult to EQ, so I'd focus on flattening out the contours of the 1-7kHz range. You should end up with something very listenable, and with very low distortion.


Chris

[vinylnvalves]

Thanks Chris. The driver has the 14khz wobble on its spec sheet in a tube, so it’s no surprise that it ends up still there.

I have been listening to those ES250 horns for a couple of weeks now, quite liking the diffused sound from an open baffle horn.
Going to try and get some Event Opals set up, to compare with my DIY creations in a few weeks.. to see how my different designs compare, should be interesting.

[vinylnvalves]

I haven’t been, doing anything to improve my set up. However I have been slowly working on a pair of “Helios” speaker cabinets for Ian. Due to the poor cosmetic appearance of the birch ply, Ian had, for these cabinets I decided to make the cabinets in a laminated construction, using 25mm wide strips (32mm for the front). Biggest challenge was cutting some wide board sapelle down for the cheek pieces. My bandsaw can only cope with 300mm, so lots of hand sawing - fortunately my drum sander can take the width so dimensioning it after splitting the board wasn’t arduous. They are nearly finished now - need a bigger radius cutter for the edge, and they will be done, ready for finishing.

IMG_2025-06-08-174118.jpeg (55.5 KiB) Viewed 14112 times

[iansr]

They look great Steve.

[Morgan Jones]

Lovely job; much better than my woodbutchery.

[Ali Tait]

Nice job indeed.

[iansr]

For anyone who is interested, the Helios was Jeff Bagby’s last design and he thought it was his best. His aim was to design a speaker that could compete with, well, anything out there. It uses some great SBA drivers including their Be tweeter in a waveguide, regarded by many as the best tweeter you can get. (The new Purifi tweeter may be about to change that . . . )

if I can make Owsten I may bring them along.