Had a productive evening at Colin's yesterday, having found a bit of time between work and gigs to go over there and get the ball rolling. This is a write-up for those interested in how that went, plus tasting notes for whoever might demo them in the future.
First up, these new speakers make the Edingdales look rather compact. They're tall and imposing and they clearly mean business.
Colin put on a CD for me, with just the mid-high section running, powered by his valve amp. Initial impressions, for female vocals and other no-bass-needed instruments, were very good. Measurements backed that up - nice and flat.
When something with bass came along, the sharp low-frequency cutoff was apparent. No problem, though - that's what the 4x 10" bass drivers are for.
Scott had passed on a suggestion of a 2nd order Bessel filter for the woofers, at 200Hz. After messing around with the Hypex amps a bit (firmware updates!), we had them up and running.
It's worth noting at this point that the amps have 3x presets which can easily be switched between. I set the lowpass-only filter as Preset 1.
We played some tunes for a bit, and the outlook was positive. That was, until I played Hey Now by London Grammar. When the bass kicks in, there are a few different notes which should all be approximately the same volume (the very low note should be a little quieter). With those initial settings, one of the middle notes made the floor shake and was much much louder than the rest.
A close-mic'd measurement of the woofers revealed nothing amiss (your usual 2nd order rolloff starting around 40Hz). Putting the mic at the listening position revealed the problem: a very tall spike at 38Hz, plus some a wide and fairly-deep dip at 100Hz.
First of all, I set about coming up with a DSP filter that would bring down the 38Hz spike, and the results were much improved. The 100Hz dip, though, was still audible: as notes played there (or instrumental harmonics passed through), things would disappear. It was fairly subtle, but once you'd spotted it, it was easy enough to pick out repeatably.
Anyway, this improvement was saved as Preset 2.
We tried a couple of things like moving the speakers closer to the back wall (remarkably little change in sound), adjusting the carpet, etc, without luck.
Normally, when I encounter a dip in the response, I'm hesitant to simply apply more power to fill it back in: I often work with PA systems which will be pushed close to the ragged edge, and applying 10+dB of boost at a frequency would simply put an amp into the limiters all night.
Colin, however, suggested that we do try to EQ it back in. A lot of boost was required (something like 18dB overall), but the advantage of large amplifiers and powerful drivers is that they don't mind if you throw a bit of power around every now and again.
So, I came up with the final DSP curve and saved it to the amps as Preset 3. The measurements showed the dip had filled in nicely, so we settled down to do some listening. We were treated to world-class sound. It's as simple as that. Some of you know where I've worked previously, and it shouldn't be surprising that Colin's speakers cheerfully demolish anything that was built there. Even the flagship £140k/pair floorstanders.
In the future, it would be nice to go back and figure out where the 100Hz cancellation was coming from and find an acoustical fix for the problem, but for now Colin seemed to be pleased with the results.
It's easy to switch between the presets, so if a fix is found for the 100Hz problem, the 2nd preset (without the 100Hz boost) would likely be suitable.
On account of the size of these speakers, and the required DSP matching to the room, I doubt that Colin would be enthusiastic about taking these out to HiFi shows. Perhaps the best way to hear them would be to form an orderly queue.
PS - the -3dB point ended up being 11Hz, -10dB at 7Hz. Proper bass.
Last edited by chris661 on Sat Nov 19, 2022 1:04 pm, edited 1 time in total.
Great day over at Colin's yesterday -many thanks for the invitation, and the hospitality from you and Lynne. Great to see Nick again after about 2 1/2 years too!
The first time I've seen the completed speakers (they were in the raw furniture / high-end kitchen worktop grade particle board when I was last over to take some in-box measurements of the drivers). Colin's done his usual beautiful work on the finish; the maple veneer suits them well, and the walnut with black banding provides some useful contrast. These are big speakers of course -but assuming you have a reasonable sized room, they aren't actually particularly imposing. Mini-monitors they are not, but after a few minutes you get used to them -perhaps my sense of scale is slightly skewed as I do a lot of substantially sized designs for our cousins over the pond. Nevertheless -visually large, yes, but not excessively so. The shape itself is conventional enough, and since the driver arrays are formed into a normal circular pattern, you tend to accept them quite quickly.
Chris has done an excellent piece of work with the active modules, their low pass and EQ, taking out a lot of the issues with room modes in the process. The one problematic mode we think needs more investigation is most likely another of those; probably on the vertical. At present, he's EQ'd it out (extremely well), as detailed above. While not his favoured approach, for home audio where even at high levels both the amplifiers and the drive units themselves are not remotely near their limits, it may end up being the preferred option as it doesn't at this point seem to be inherent to the speaker itself.
As for the sound, it's a little reminiscent, as I suspected, of the big JBLs of the 1970s -as in the proper ones used by studios, most of which our American friends sensibly kept for themselves. It does some of what you get from midrange horns, sans the colouration frequently encountered. Not exactly the same, but they do share a few traits in that regard. General response is smooth; non-linear distortion very low -no surprise given that the bass units and tweeter have some of the best motor designs on the market, and there are 14 small-coil drivers per channel handling the midrange (i.e. each unit only does 1/14 of the work over their operating range). Like Chris, I can think of quite a few extremely expensive speakers that frankly don't do what these can, even without a bit of final fine-tuning, so I'd say a fitting swansong for Colin's speaker-building indeed.
Just caught up on the postings after the very successful weekend. As you may guess I haven't been on-line until this morning, when I have been ordering the upgrade components for the passive filter and have now just had the time to log on to the forum before I slip back into my listening room to further rediscover my music collection.
I have to say these speakers have ticked all my expectations and some. To my ears they are quite awesome. It's so refreshing to be able to concentrate on listening and following the bass notes in a piece of music and still follow the rest of the recording very clearly. There is very clear separation of individual players and instruments within the stereo mix. Just need to bottom out the 100Hz room suck-out which we, by this I mean Chris, with the help of me, Nick and Andrew. This minor niggle we hope to bottom out the weekend Saturday 3rd December.
Until then I hope to have the passive filters installed, with the upgraded components, inside their dedicated space inside the speakers.
Anyway, thanks guys for the congrats and any you guys are most welcome to pop over for a listen just get in touch via the forum if you don't already have my personal contact details.