Harbeth use veneered MDF, no solids AFAIK. It's difficult to use solids with thin-wall construction, beyond the beechwood stringers the BBC used in their original LS3/5a prototypes & specified for production models as it provided the best impedance mismatch they could manage between the baffles & damped thin-ply box structure.
Thanks Scottmoose.
I gave this speaker some thoughts as I was lying in bed this morning. I know he did make some tweaks to the driver but I'll bet he gets the sound out of the wood. What I think he did was make a musical instrument with a speaker. Harley uses 3.2cm (~1.25") oak, that's thick wood, I'll probably try 5/4 which nominals out at ~1-1/16" as 5/4 gives me more wood options.
I walked around the house this morning looking at the doors I built, some I did over 25 years ago, to refresh myself and check for cracking. The large French doors were built over 25 years ago out of 8/4 maple and for about ten years before I put in the sunroom they faced harsh northern winters in NY's Catskill Mountains. While they were mortise and tenon joints I only saw slight cracking on the outside of the doors on the bottom where snow sat on and off for years. The width of the bottom panel is ~8-3/4" the glass is double pain thick glass that the glass place should have used 1/8" glass on but use 1/4" so each glass panel is a good 50 pounds if I remember so there's a lot of weight on the bottom plate.
Even the photo with the inlay never cracked but it is a shorter grain difference.
I think I can reliably get up to about 9" of grain difference before I start to see trouble, I'll have to think about joints and gluing.
I'd like see how Pearl did the tops of those speakers, it looks like at the bottom opening they but joined them at 45 degrees, I imagine there's a spline along the length?
I gave this speaker some thoughts as I was lying in bed this morning. I know he did make some tweaks to the driver but I'll bet he gets the sound out of the wood. What I think he did was make a musical instrument with a speaker. Harley uses 3.2cm (~1.25") oak, that's thick wood, I'll probably try 5/4 which nominals out at ~1-1/16" as 5/4 gives me more wood options.
I walked around the house this morning looking at the doors I built, some I did over 25 years ago, to refresh myself and check for cracking. The large French doors were built over 25 years ago out of 8/4 maple and for about ten years before I put in the sunroom they faced harsh northern winters in NY's Catskill Mountains. While they were mortise and tenon joints I only saw slight cracking on the outside of the doors on the bottom where snow sat on and off for years. The width of the bottom panel is ~8-3/4" the glass is double pain thick glass that the glass place should have used 1/8" glass on but use 1/4" so each glass panel is a good 50 pounds if I remember so there's a lot of weight on the bottom plate.
Even the photo with the inlay never cracked but it is a shorter grain difference.
I think I can reliably get up to about 9" of grain difference before I start to see trouble, I'll have to think about joints and gluing.
I'd like see how Pearl did the tops of those speakers, it looks like at the bottom opening they but joined them at 45 degrees, I imagine there's a spline along the length?
Attachments
Harvey / Pearl haven't modified the drive unit as such -it's a custom unit produced specifically for them by Markaudio.
To a point, although in most cases what you really want is mechanical stability and individual / structural resonant profiles which are unlikely to cause unwanted audible colouration, which is one reason they've gone for a tight-grain slow-growth French oak of that thickness. A loudspeaker is not a musical instrument -its job is to accurately reproduce the instruments that have been recorded, not add major panel resonances of its own devising (aka 'distortion'). I've worked with Harley -the Sibelius is his design, but I know what's in it, what the load & dimensions are & I've done some minor confirmatory load modelling for him, as well as offering some more general feedback / guidance on matching etc. It took him a long time to empirically develop since they wanted solid material for the cabinet, and to do that well you need to both prevent movement / cracking over the long term in as many demanding conditions as possible, & to select the materials & manipulate their resonant profiles (since it's not possible to eliminate resonance, only move it about) so you aren't plagued by unnatural colouration. Bernie is great at this sort of thing too, as you can see from some of the images Dave posted.
Edit: lovely work on those doors BTW.
Last edited:
Okay, thanks - good to know, personally I'd rather build out of ply or MDF and vernier, much more flexibility and nicer wood choices besides I think they build a stronger more stable box. I don't know what his care instructions are but I'll bet relative humidity is in there somewhere.
Thanks on the doors.
Just out of curiosity I'd like to see a side by side but I guess that isn't ever going to happen.
I was going to mention quality ply + veneer. Dave's going to freak out if he sees "MDF" mentioned in your build.
Yeah those arched glass doors are really cool.
jeff
Last edited:
Unlikely. And even if it happened, from the outside you would not be able to tell anything.
dave
Almost. MDF is not really a suitable build material unless it is all you can get.
dave
Thanks Dave, you guys are really saving me time and work, much appreciated. No problem going with cabinet grade ply.
To answer that (either way) I'd have to break a legally binding non-disclosure agreement about commercial details, so with respect to all involved, I can't answer certain questions. I stress there's nothing to be read into that: I'm simply saying that as far as design details go, I can't give any information beyond what's in the public domain (or can be be reasonably inferred from that only).
Not really. They simply show an average of human hearing sensitivity at various frequencies (ignoring damage, decline from age etc.), and that's what we live with, sans any form of manipulation in our day-to-day lives. It can help with off-axis / power response, step-loss etc. though.Might the MarkAudio drivers tilted response in the higher octaves contribute to the speakers sounding fairly correct if we consider equal loudness and Fletcher-Munson curves.
You'd be surprised actually (I certainly was). The last time we spoke on Zoom, Harley showed me a pair of his own Sibelius; from fallible memory one had been sitting more or less in front of a radiator for the best part of 4 - 5 years. No sign of any movement. I can't say I'd be that brave myself, but a/ I didn't design & build them, and b/ I've spent the last 5 years living on an average of £462 per month (gross), so when you're in your mid-40s and as broke as I am, you can't afford to be brave.
I remember something in an interview or maybe on Harley's videos, about switching to a square wire for the voice coil....
Something about a fiddly noise when reproducing an instrument, and Mark knowing exactly what to do.
That's about all I remember about driver mods, maybe they coat them, idk.
I see no reason not to use baltic birch or appleply (say 13 layers in 3/4") plywood if going for cat's meow....
Something about a fiddly noise when reproducing an instrument, and Mark knowing exactly what to do.
That's about all I remember about driver mods, maybe they coat them, idk.
I see no reason not to use baltic birch or appleply (say 13 layers in 3/4") plywood if going for cat's meow....
Last edited by a moderator: