Something stirs in the Undergrowth

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IslandPink
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#2791 Re: Something stirs in the Undergrowth

Post by IslandPink »

The ScanSpeak 2905-9500's are among the best soft domes, Ed, but I heard definitely more tone in those Beryllium SB's, without harshness.
Scottmoose wrote: Tue Mar 09, 2021 12:26 pm AMTs and ribbons I tend to be a bit wary about. I like good ones, but with a handful of exceptions smaller examples tend to have poor distortion performance at the bottom end, requiring a highish XO frequency and higher order slopes. Coupled with the limited vertical dispersion ribbon types tend to have, that can sometimes make for questionable system polars, which in turn can affect tonal presentation. Good ones though as noted -great. I do rate the big Beymas for instance.
AMTs are fairly common nowadays but also diverse, it's difficult to generalise. Some can go down quite low. I have never lived with one ; I know a couple of people who don't rate them as a substitute for a compression driver or ribbon, though.
As far as ribbons, I suggest they need either a higher crossover, or a steep slope - not both. I use the Aurum G3's with a transitional 1st/2nd order slope but somewhere around 3 to 3.5kHz, and I haven't heard anything better, driven by the 45 amp.
These concerns about the polar pattern, well, maybe my ears are 'blind' to what that does to the sound. I have a few gripes with the OB set-up I have now, but the treble is the one bit i wan't be changing, it's spacious , natural, detailed, dynamic , colourful .... or maybe I'm just biased ...
Maybe Nick, Ali or SimonC could correct me ( go ahead ) .
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#2792 Re: Something stirs in the Undergrowth

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simon wrote: Tue Mar 09, 2021 2:25 pm A fascination discussion chaps, thanks. Lots of food for thought, though it seems, perhaps unsurprisingly, that there's no substitute for hearing all the alternatives for one's self. Which is a rather expensive mission.
It's not that expensive to travel to Denbigh and hear at least two of the options. Some time soon !
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#2793 Re: Something stirs in the Undergrowth

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Scottmoose wrote: Tue Mar 09, 2021 12:32 pm Zero advantage to them over aluminium, it was just a marketing stunt, a bit like titanium is -again, little or no benefit over aluminium or an aluminium-magnesium alloy (which is what Seas often use, not for marketing purposes, as they're often just described as aluminium).
Just a quick FWIW that in the PA world, titanium diaphragms do have their advantages: they put up with considerably more mechanical abuse before shredding.

I found this out when getting a demo of the Powersoft T-series amps - the rep had only received them the evening before, so this was the first demo in the UK of those amps. Took my speakers into the venue, connected the amps up, dialled in some basic processing, messed around saving the presets, and pressed Play.

Buzzing was happening on the bass notes, and at a fairly considerable power level. I also spotted the 10" midbass drivers seemed to be flapping around rather a lot.

Checked the processing, and all the filtering had been bypassed while saving. We'd been playing dubstep at feel-the-bass levels for a few minutes when that one was figured out, and all the while the compression driver diaphragms had been hammering against the phase plugs. I've known aluminium diaphragms turn to shrapnel under much gentler circumstances, but the titanium diaphragms had nary a scratch on them.

The compromise is that the aluminium diaphragms seem to have slightly better self-damping, so the >12kHz range (on a 3" diaphragm) is smoother. At 130dB@1m, though, nobody minds too much.

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#2794 Re: Something stirs in the Undergrowth

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IslandPink wrote: Tue Mar 09, 2021 6:59 pm It's not that expensive to travel to Denbigh and hear at least two of the options. Some time soon !
Wow, just the thought of that is freaking me out. I've put two half tanks if petrol in the car in a year! Looking forward to it :-D. But it will probably be a long time yet :-(.
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#2795 Re: Something stirs in the Undergrowth

Post by Ali Tait »

IslandPink wrote: Tue Mar 09, 2021 6:57 pm The ScanSpeak 2905-9500's are among the best soft domes, Ed, but I heard definitely more tone in those Beryllium SB's, without harshness.
Scottmoose wrote: Tue Mar 09, 2021 12:26 pm AMTs and ribbons I tend to be a bit wary about. I like good ones, but with a handful of exceptions smaller examples tend to have poor distortion performance at the bottom end, requiring a highish XO frequency and higher order slopes. Coupled with the limited vertical dispersion ribbon types tend to have, that can sometimes make for questionable system polars, which in turn can affect tonal presentation. Good ones though as noted -great. I do rate the big Beymas for instance.
AMTs are fairly common nowadays but also diverse, it's difficult to generalise. Some can go down quite low. I have never lived with one ; I know a couple of people who don't rate them as a substitute for a compression driver or ribbon, though.
As far as ribbons, I suggest they need either a higher crossover, or a steep slope - not both. I use the Aurum G3's with a transitional 1st/2nd order slope but somewhere around 3 to 3.5kHz, and I haven't heard anything better, driven by the 45 amp.
These concerns about the polar pattern, well, maybe my ears are 'blind' to what that does to the sound. I have a few gripes with the OB set-up I have now, but the treble is the one bit i wan't be changing, it's spacious , natural, detailed, dynamic , colourful .... or maybe I'm just biased ...
Maybe Nick, Ali or SimonC could correct me ( go ahead ) .
Nope, treble was great as far as I remember.
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#2796 Re: Something stirs in the Undergrowth

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IslandPink wrote: Tue Mar 09, 2021 6:57 pm AMTs are fairly common nowadays but also diverse, it's difficult to generalise. Some can go down quite low. I have never lived with one ; I know a couple of people who don't rate them as a substitute for a compression driver or ribbon, though.
Presumably it depends what they're trying to do with them, and the individual characteristics of the units they're using.
As far as ribbons, I suggest they need either a higher crossover, or a steep slope - not both. I use the Aurum G3's with a transitional 1st/2nd order slope but somewhere around 3 to 3.5kHz, and I haven't heard anything better, driven by the 45 amp.
I don't doubt it for a moment, but it's heavily dependent on the unit. Many small planars, be they ribbons, AMTs or magnetostatics have rotten distortion at the bottom end of their range, so in those cases a low-order crossover at 3KHz - 3.5KHz isn't always sufficient. Not always the case, and a few can hack it, but in a lot of others -don't go there. ;)
=These concerns about the polar pattern, well, maybe my ears are 'blind' to what that does to the sound. I have a few gripes with the OB set-up I have now, but the treble is the one bit i wan't be changing, it's spacious , natural, detailed, dynamic , colourful .... or maybe I'm just biased ...
Unlikely that you're blind to anything, we just all tend to focus on / value different things. The effect of polars is usually most apparent in the range where you're crossing between two drivers that have different dispersion behaviour at & around that point. Daft example: a 10in woofer + 3/4in dome tweeter crossed at 3KHz. The woofer is beaming heavily, while the tweeter is merrily radiating over a much wider angle over the same frequency range. The shift in the system polar behaviour can cause some shifts in tonal presentation through that region. I generally aim to get the polars as consistent as possible out to about 30 degrees off-axis through the XO region, which is one of the reasons I like lower crossover frequencies. YMMV as always.
Last edited by Scottmoose on Wed Mar 10, 2021 11:18 am, edited 1 time in total.
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#2797 Re: Something stirs in the Undergrowth

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chris661 wrote: Tue Mar 09, 2021 8:52 pm Just a quick FWIW that in the PA world, titanium diaphragms do have their advantages: they put up with considerably more mechanical abuse before shredding...
The compromise is that the aluminium diaphragms seem to have slightly better self-damping, so the >12kHz range (on a 3" diaphragm) is smoother. At 130dB@1m, though, nobody minds too much.
Fair point, I was speaking from a regular home audio / HE home-audio perspective. Pro-audio usually has a somewhat different set of requirements, albeit often overlapping; 130dB @1m is a very rare requirement for most home users, albeit all other things being equal the more headroom you have available, the better.
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#2798 Re: Something stirs in the Undergrowth

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Scottmoose wrote: Wed Mar 10, 2021 11:06 am I don't doubt it for a moment, but it's heavily dependent on the unit. Many small planars, be they ribbons, AMTs or magnetostatics have rotten distortion at the bottom end of their range, so in those cases a low-order crossover at 3KHz - 3.5KHz isn't always sufficient. Not always the case, and a few can hack it, but in a lot of others -don't go there. ;)
I wouldn't bother with a small one myself, unless it could be used from say 5kHz. The Aurum G3 is a bit more serious ( or the G2 ) . But I also think people should not be thinking in terms of them being used in a typical 2-way with a bass/mid unit. My experience is that they can only interface to something like a compression driver or a small light-coned full range driver. You need to have something that gets closer to the low level tone and dynamics that the ribbon can deliver, for it not to sound like a disjoint.
Scottmoose wrote: Wed Mar 10, 2021 11:06 am Unlikely that you're blind to anything, we just all tend to focus on / value different things. The effect of polars is usually most apparent in the range where you're crossing between two drivers that have different dispersion behaviour at & around that point. Daft example: a 10in woofer + 3/4in dome tweeter crossed at 3KHz. The woofer is beaming heavily, while the tweeter is merrily radiating over a much wider angle over the same frequency range. The shift in the system polar behaviour can cause some shifts in tonal presentation through that region. I generally aim to get the polars as consistent as possible out to about 30 degrees off-axis through the XO region, which is one of the reasons I like lower crossover frequencies. YMMV as always.
Yes, I see.
However this does tend to suggest that for polar matching a ribbon would be a better bet than a dome tweeter - given its more limited dispersion pattern....
But then as I have found, comments above.

I remember talking to Peter Qvortrup about why he always used 3/4" domes on the AN speakers, and he emphasised the need for the widest possible coverage in the HF ...without fully explaining why. He said he wouldn't consider ribbons, for this reason.
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#2799 Re: Something stirs in the Undergrowth

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As always, YMMV. ;) A ribbon mounted vertically is highly directional in that plane, but usually has very wide horizontal dispersion, so for something like a 2-way, many smaller types (say, something with a faceplate size out to about 120mm) are an utter pain in the neck as they can't get low enough for the polars of the woofer to even begin to match up. Better for 3-ways, although you then need to watch the centre-to-centre spacing as in an ideal world, you don't want to be crossing at more than 1 wavelength distance.

Re Peter -different strokes for different folks. Some like waveguides for e.g. specifically because of the controlled directivity & reduced reflections that can happen with direct radiators. I tend to prefer direct radiators over waveguides (although I do like compression mid-tweets with a good horn, so nobody can ever accuse me of consistency ;) ) so I've a certain conceptual agreement with him on that, if not necessarily with the execution. :mrgreen:
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#2800 Re: Something stirs in the Undergrowth

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Yes definitely, I would not agree with Peter re. ribbons, I have had nothing but success from the G3's.
I did do some Quasar tests at the same time as I posted the horn stuff. I just didn't get around to posting it, as I couldn't reconcile the measurements with the listening experience, but here they are anyway.
This is for one 'unit' without the tweeters ( since the tweeters are bi-amped, it was a bit messy to include them ). Hence the response should appear to roll off beyond 3kHz.

First one is from a listening distance of 2.8m, with an attempt to smooth things out by averaging 7 different microphone and speaker positions. Obviously the fundamental characteristics of the room shape are still in this plot.
Quasar_2.8m_various_SPL_Avgof7.jpg
Quasar_2.8m_various_SPL_Avgof7.jpg (78.89 KiB) Viewed 5928 times
This one is taken much closer ( 30cm ) to the FX120 pair, to try to establish how that looks in the upper midrange :
Quasar_30cm_FX120_SPL_Avgof2.jpg
Quasar_30cm_FX120_SPL_Avgof2.jpg (74.49 KiB) Viewed 5928 times
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#2801 Re: Something stirs in the Undergrowth

Post by JamesD »

Interesting measurements - I can relate to the first one in blue as it has nice well behaved response from 75Hz to 16/17KHz with the top couple of octaves gentle sloping down... taking trend lines lines from the response curve rather than specific frequencies - I would expect the typical FX120 sound and its clear that the two drivers have a nicely integrated response...

The green one is somewhat flatter trend wise but is showing several specific problem areas that I suspect are measurement artefacts of one form or another - but that could be wishful thinking on my part :D The artefacts may well be due to the two drivers interfering together at this close measuring distance and include secondary radiation effects from the baffle and driver edges with both drivers re-radiating from each other - close measuring tends to exacerbate these effects... this is a guess but I have seen this before when using multiple drivers and close measurements - it can be a problem, for instance, with MTM, where some need to be measured from a greater than 1m distance before they integrate properly... It would be interesting to repeat the measurements with the microphone at different heights - say from below the bottom driver to above the top driver and compare the measurement set...

ciao

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#2802 Re: Something stirs in the Undergrowth

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I think you're right that there are likely measurement artifacts from the close driver pair.
From a typical listening distance, the perceived vocal quality is excellent in the upper (female) range, without any obvious harshness, and blends very nicely to the ribbons.
The measurements from a distance suggest that the lower vocal range would be emphasised, but in practice, the opposite is true, it's the lower end of the male vocal range that sounds weak.
In the bass, the upper bass sounds weaker ( I think this, and the lower mids weakness are all to do with the compromises needed to attenuate the Supravox ) and the lower bass sounds pretty strong, at least down to the lower end of the bass guitar range.
So all in all, not entirely encouraging re. measurement vs. listening, which I think is why I was slow to post this info.
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#2803 Re: Something stirs in the Undergrowth

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This won't appeal to everyone, on the basis of the cost involved, but just wanted to report that I received a 2.7m pair of EWA's ( Elsdon Wonfor Acoustic ) top cables, LS-80 today. I'd bought some older LS-25's last year s/h which were surprisingly good in many ways but frustrating ( slow timing) , then in the last two weeks I've had a loan of the next level LS-40 ones, which were very good, but it just spurred me on to get the top ones, while i still can afford them and hear properly !
Anyway they are stupidly good, loads better than TQ Ultra Black, they have improved every aspect of the sound from top to bottom.
I've only been using them 2 hours, they will probably improve a more too.
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