Alistair W Posted May 24, 2017 Posted May 24, 2017 (edited) This is my take on the classic british monitor speaker - think ATC SCM100 or Harbeth 40.2 I was lucky to buy off another member some very nice drivers - the Audio Technology C-Quenze midrange, and Raal 70-20XR tweeter. I'm pairing them up with the Audio Elegance TD12S 12" woofer. After hearing the AE dipoles in the Kyron room at the last audio show, I was happy to purchase a pair of the TD12's from John at AE. So we have: Raal 70-20XR ribbon tweeter Audio Technology C-Quenze 6" midrange AE TD12S 12 inch woofer Crossover is 12db/oct LR2, with crossover at 350 Hz and 2.8 kHz Edited May 24, 2017 by Alistair W Typo! 1
Alistair W Posted May 24, 2017 Author Posted May 24, 2017 I'm building up a set of test cabinets in MDF so I can tweak the design until I'm happy with it. THEN build some nice boxes! Mitred cuts on top and side - done with circular saw and guide rail Routing some rebates on a side panel so the front and back panels just slot in First box assembled and being glued. I've just placed the back panel (without glue) to hold everything together Dimensions are 820mm high x 425mm wide x 470mm deep Internal volume will be about 100 litres This is a ported design, tuned to 37Hz to suit the woofer. 7
Guest Peter the Greek Posted May 24, 2017 Posted May 24, 2017 Watching with most interest. I've been wanting to pair a TD8X with a Raal
lusk Posted May 24, 2017 Posted May 24, 2017 Good driver selection, it should sound very nice when finished. Aim to keep the Raal at ear height if you haven't already considered it has great horizontal off-axis but its a ribbon so vertical needs to be considered. 1
Alistair W Posted May 28, 2017 Author Posted May 28, 2017 On 25/05/2017 at 9:31 AM, lusk said: Good driver selection, it should sound very nice when finished. Aim to keep the Raal at ear height if you haven't already considered it has great horizontal off-axis but its a ribbon so vertical needs to be considered. Yeah, I thought as much. They'll be going on stands to get the tweeter height just right. Only need about 200-250mm off the floor. Why didn't I do them as floorstanders? Just like the look of monitors on stands! I'm sketching out a pair of stands to be welded out of steel, and will be chatting to a few local steel fabricators, I hope this isn't too small a job to interest them. 1
Upfront Posted May 28, 2017 Posted May 28, 2017 Yeah, I thought as much. They'll be going on stands to get the tweeter height just right. Only need about 200-250mm off the floor. Why didn't I do them as floorstanders? Just like the look of monitors on stands! I'm sketching out a pair of stands to be welded out of steel, and will be chatting to a few local steel fabricators, I hope this isn't too small a job to interest them. You can buy welders cheap on GT. Give it a go yourself
henry218 Posted May 29, 2017 Posted May 29, 2017 Good driver selection, it should sound very nice when finished. Aim to keep the Raal at ear height if you haven't already considered it has great horizontal off-axis but its a ribbon so vertical needs to be considered. May i ask you to elaborate more on the vertical dispersion of the 70-20? Is it your project or were you listening to a commercial speakers?Sent from my iPhone using Tapatalk
MRG Posted June 1, 2017 Posted June 1, 2017 (edited) I'm into a similar project with one speaker sounding very good and the other waiting to get its RAAL after trying Scan 6600 domes. Mine has RAAL 150-40D ATC SM75-150 AE TD10X Crossing at 300 and 3k. Started with LR2 everywhere but now favoring 6dB slope on the mid's high side. It seems to integrate better with the RAAL. And LR3 on the bass to stop it muddying the very clean mids. Excuse the rather phallic looking tuning port. Just trying different lengths experimentally as modelling hardly ever is right. Edited June 1, 2017 by MRG 2
Alistair W Posted June 1, 2017 Author Posted June 1, 2017 Nice one MRG! Interesting about the woofer-mid crossover. I'm thinking the ATC mid would have a natural rolloff below 300, so that combined with an LR2 electrical would give something approx 3rd order. Which could explain why the woofer sounds better LR3? I'm thinking LR2 woofer + mid gave a bit of a dip(?) around the crossover point. Is that an open baffle mid / tweeter section? It's hard to tell from the photo. What's your opinion of the plastic trim on these AE drivers? Personally I don't like it, think it looks a bit cheap. I'm thinking of a removable front baffle to hide the mounting screws and woofer frame from view. Just need to find some time to finish the first cabinet then i can make some measurements.
MRG Posted June 1, 2017 Posted June 1, 2017 (edited) Alistair, Exactly how you described it with the dip. I wonder it the same thing happened at the tweeter? Natural roll-off of mid combined with LR2 giving a LR3. So making it a 1st order actually matched the tweeter's LR2 better . Yes it's open baffle - a pretend one as both mid and tweeter drivers are sealed. That trim caused me some issues and will contort with reasonably sized bolts. On the plus side, you don't need a gasket. Edited June 1, 2017 by MRG
Alistair W Posted July 16, 2017 Author Posted July 16, 2017 In between winter colds and bad weather I haven't had much progress this past month! I was able to get a few hours in this weekend and continue building the 2nd cabinet, as well as start doing cutouts on one of the front baffles. The cabinets are 16mm MDF with another layer of 12mm MDF for 28mm thickness. Getting too heavy to lift so i wheel them around on a trolley! Here is a cabinet having the 12mm layer glued on. Wish I had a few more clamps.. As mentioned earlier in the thread, I don't like the plastic trim ring fitted on the AE woofer, so I'm recessing the woofer behind the front baffle. This means the baffle has to be removable - lots of screws around the perimeter. As I'll probably live with the MDF boxes for some time while tweaking the crossover, I've decided to make nice front baffles out of some bamboo plywood. The rest of the box will be painted matt black. I had to route a cutout for the woofer into both the front of the box, and the removable baffle. The woofer is slightly recessed into the front face of the box by about 5mm. The woofer frame protrudes out from the box, so the back of the baffle is routed to fit around the woofer frame. I used the router to round over the woofer cutout on the front baffle, nearly wrecking one baffle when the depth adjustment came loose and the router bit started digging in. That rounding-over bit is a ba***rd of a thing to use, it shakes the whole router like crazy and the depth adjustment wanders if not done up tighter than tight! Front baffle with midrange and woofer cutouts. Tweeter cutout will be next. Trial fit of the woofer. The baffle fits in front and hides the woofer frame. Trial fit of the midrange. you can also see the rounded over woofer cutout. 5
Alistair W Posted November 7, 2017 Author Posted November 7, 2017 On 5/29/2017 at 5:39 AM, Upfront said: You can buy welders cheap on GT. Give it a go yourself I did make the stands myself in the end.. Top is 5mm steel plate and legs are 40x40 square section. I had the steel plate and legs cut to size by a local steel merchant, then a friend offered to help with the welding. We were able to use the metalwork facility at our local high school, so I got a quick course in MIG welding! Tack welding one of the legs: One of the better welds I did. Some not so good.. All welded, ready for finishing The welds turned out a bit rough so I'm adding some automotive filler to smooth them out. I'll sand this back before painting. Finally, here's a video we took of the welding - judge for yourself ;-) https://www.youtube.com/watch?v=ILWSp0m9G2U
Guest BobbyD Posted November 7, 2017 Posted November 7, 2017 Made similar stands for my 2 way to get the tweeter to the right height, the Raal’s are a great choice......great minds....
Al.M Posted November 7, 2017 Posted November 7, 2017 Excusing the potentially less than perfect driver implementation, I’m playing around with 68L and 95L bass modules with removable front panels and different size midrange driver modules also with removable fronts so different driver combos can be used without having to build entire new modules. In the picture below getting great sound from an Eton 581/50 11 inch woofer used in Avalon Eidalon speakers, venerable old Scanspeak 13w 8640 midrange and Scanspeak D2904/7000 ring radiator tweeter. The Eton hexacone woofer goes deep, textured with subtle low and midbass detail, the Scanspeak paper mid is highly detailed, images nicely and forgiving, and the Scan top range ring radiator is absolutely stunning with among the best detailed and accurate dome/ring radiator sound, crisp and not splashy or sibilant (subjectively sounds better than Scan 9900, 9800 or 9500, Seas Millenium or Accuton C23 etc). Will try some other midrange units in the collection like Vifa P13WH poly cone, ATC 150 dome, Eton 5 inch hexacone and Focal Audiom 7 Kevlar.
MrRogers Posted November 16, 2017 Posted November 16, 2017 Made similar stands for my 2 way to get the tweeter to the right height, the Raal’s are a great choice......great minds.... Are the speakers a DIY?
Alistair W Posted January 17, 2018 Author Posted January 17, 2018 Just realised I never posted an update on my speakers. They're up and running with the first cut of the crossover, and raw cabinets. Here's the unfinished cabinet, cat not really helping.. Crossover, 12dB/octave Linkwitz-Riley: The cabinets are 'veneered' with a thin bamboo plywood I sourced from Plyco in Alphington (Melbourne). It's 2.5mm thick, and called 'laser ply'. It glued on easily with contact adhesive and looks fantastic. The front panel is made from 15mm bamboo plywood and needs a final trim to size and rounding over. I'm planning to finish the cabinets with a varnish or furniture oil. They were demo'd at the December DIY night of the Melbourne Audio Club and worked VERY well with Bob Field's triode amp: I'll be tweaking the crossover after they've got a few hours on them, but I like what I'm hearing already! -Al 5
lusk Posted January 17, 2018 Posted January 17, 2018 (edited) Hi Al, Looking good, did you end up going with 1 x cap on the RAAL like suggested or something else? I run sort of similar with AT 18H, it sounded best with 1 x cap but didn't sum together that good with the midrange. I since changed to adding inductor and capacitors like suggested for the other RAALs but it seems to have lost its nice ribbon sparkle. Just wondering what you did. Edit: maybe you did is that 4.7uF for the RAAL in your crossover picture? Edited January 17, 2018 by lusk
Alistair W Posted January 17, 2018 Author Posted January 17, 2018 Also.. The cabinets are sealed boxes, not ported. I changed my mind during construction and decided to build them as sealed boxes, as this config has potentially better transient response (less group delay). The woofers are AE speakers TD12-S, so intended for sealed use. The bass is somewhat light, but you notice it when it's there. No boominess at all, just very clean. I expect things will change as the drivers run in, so will give my impressions after a month or so of listening. The other thing I've noticed is how much more efficient they are, compared to the little bookshelf speakers they replaced. I'm running a 70 watt class-D amp and don't need the volume much above 2 or 3 on most recordings. I'm estimating about 91dB/1W for these, vs probably 85dB for the old bookshelf speakers -Al.
Alistair W Posted January 17, 2018 Author Posted January 17, 2018 Hi Lusk, Yep, 4.7uF on the RAAL, running on the 9 ohm tap for ~91dB sensitivity to match the other drivers. I used an online calculator to derive the crossover values, and put a zobel network on the mid and bass drivers to make them a simple 6 ohm resistive load. The crossover is 2nd order Linkwitz-Riley. 2 minutes ago, lusk said: Hi Al, Looking good, did you end up going with 1 x cap on the RAAL like suggested or something else? I run sort of similar with AT 18H, it sounded best with 1 x cap but didn't sum together that good with the midrange just wondering what you did. Edit: maybe you did is that 4.7uF for the RAAL in your crossover picture? 1
lusk Posted January 17, 2018 Posted January 17, 2018 Thanks Al, Am also a huge fan of going sealed bass, l run 2 x 10"sealed each side. Need to run 2 per side as drop in efficiency from each driver being made for sealed application. Do you have a TD12-S with a dust cap or SBP-12? Normally properly made sealed driver will have low fs and lower efficiency as they add more mass to go low. The TD12-S is more a driver that can do both. Could run class D plate amp on it and push it to go lower though.
Alistair W Posted January 17, 2018 Author Posted January 17, 2018 Hi Lusk, John at AE Speakers kindly made a custom version of the TD12-S for me, swapping the phase plug for a dust cap. It's purely for aesthetic reasons as I didn't like the woofer having a phase plug, and the midrange without one! As I'm only running the woofer up to 360 Hz, John agreed there should not be any disadvantage from removing the phase plug. The SBP-12 didn't match the other drivers in terms of sensitivity, but the TD12-S was 'just right' 29 minutes ago, lusk said: Thanks Al, Am also a huge fan of going sealed bass, l run 2 x 10"sealed each side. Need to run 2 per side as drop in efficiency from each driver being made for sealed application. Do you have a TD12-S with a dust cap or SBP-12? Normally properly made sealed driver will have low fs and lower efficiency as they add more mass to go low. The TD12-S is more a driver that can do both. Could run class D plate amp on it and push it to go lower though. 1
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