Something stirs in the Undergrowth

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Re: Something stirs in the Undergrowth

Post by IslandPink » Mon Nov 04, 2019 6:11 pm

Form an orderly queue please !
Plenty of room upstairs, have your money ready.
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Re: Something stirs in the Undergrowth

Post by IslandPink » Mon Nov 04, 2019 6:24 pm

Nick wrote:
Mon Nov 04, 2019 8:55 am
Which (at least in the case of two of them from Munich) are not without their own issues. The AER's were the best, but only in one of their own speakers, the other use they made of them were also questionable to my ears.
I would still cross to a ribbon at eg. 4kHz, but it's still something of a gamble as to which has the best midrange.
But all of the current AER's seem to have a Q of under 0.3, so they would be a poor choice on OB as I found with the FE208Ez.
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Re: Something stirs in the Undergrowth

Post by IslandPink » Mon Nov 04, 2019 6:26 pm

ed wrote:
Mon Nov 04, 2019 10:01 am
is the price shown on the website not valid? It says 680 euros each.
I don't think so - I've seen higher prices elsewhere. I think this website came out when they launched and the price is out of date. If I try the 'Contact' or 'Reply' page and attempt to send questions, it sends some sort of failure message when you press 'send'.
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Re: Something stirs in the Undergrowth

Post by IslandPink » Mon Nov 04, 2019 6:27 pm

steve s wrote:
Mon Nov 04, 2019 12:32 pm
Goes to show how important your bass drivers are for good reproduction of male and female voices Mark.
Yes, it is quite thought-provoking.
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Re: Something stirs in the Undergrowth

Post by IslandPink » Mon Nov 04, 2019 6:38 pm

Some comments below in bold :
steve s wrote:
Mon Nov 04, 2019 12:47 pm
I may be off track here Mark but the fx120 are likely to struggle to reproduce the vocal fundamental?
Yes, that's why they are in the 'Quasar' series crossover mode with the Supravox 285GMF :D

My lowthers only came into their own with some female vocals.. some where too low, it wasn't until I combined them with the big goodmans, then all was exposed ?
My musical tastes then broadened
See above.
If you look on page 165 at the graphs, specifically the one under 'Here's an average of everything', you can see there's no lack of SPL in the 80 to 200Hz region where the drivers blend.


It's likely the Enviee may well struggle looking at the measurements?
No , its parameters are very close to the AER Mk.1 which I liked very much in the key areas when combined with the 285GMF

It's how all the drivers play together that counts...

Edit.. I'm not sure how you are evaluating the drivers Mark ( open baffle or back horn?) But if its in open baffle are you cutting the bottom end?
As above. I had a circuit diagram of the crossover not too far back. See also many pictures of the OBs in recent months.

I could not run my Lowthers wide open in baffles, they needed a cap cutting the sub 100hz or they too could sound fuzzy... just a thought ?
Makes sense. My crossover is effectively around 180Hz I think.
Further to this, the measurements in the lower vocal range make me wonder if there is a better position for the OBs in the room that would help male vocals, this is something SimonC might be able to help me explore, when he visits.
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Re: Something stirs in the Undergrowth

Post by IslandPink » Mon Nov 04, 2019 6:44 pm

Toppsy wrote:
Mon Nov 04, 2019 1:23 pm
Mark,
Have you checked out any the SB Acoustics PA drivers? They trade under the SB Audience name: http://www.sbaudience.com/

I understand they are developing a Satori range of woofers with their new Textrene CF cones. They certainly look very interesting being a woven carbon fibre material. Check out SB Acoustics web site in their 'coming' and 'news' pull down menus : https://www.sbacoustics.com/
Thank you Colin - that's very useful. I have just started looking through, and there is at least one 8" driver in the PA range that looks interesting. The Rms value is not too high for a PA unit, which is good.
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Re: Something stirs in the Undergrowth

Post by IslandPink » Mon Nov 04, 2019 6:48 pm

vinylnvalves wrote:
Mon Nov 04, 2019 5:30 pm
There seems to some discussion about this 10” FR driver which should be good under a ribbon. It’s a copy of the coral drivers of old. https://www.diyaudio.com/forums/full-ra ... und-3.html
Ah yes, I had seen that thread a few weeks ago, but there's more on there now. I will catch up later. I like the coral-style cone with the radial ridges. Still a bit nervous about forking out for a Chinese driver though.
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Re: Something stirs in the Undergrowth

Post by IslandPink » Mon Nov 04, 2019 11:21 pm

Meanwhile back on Plan A, I did some sketching in the Lake District with Hornresp data, graph paper, a piece of string and a pencil.
The script at the top says "horizontal expansion - linear from 10 to 48cm"
LHorn208Ez_2p5m.jpg
The Yuichi and ribbon would sit inside the bend of the 'L' horn.
I'm going to have a look at all the spare fibreboard I bought to make the Horst double-horn and see if I could do a straight prototype of this, to evaluate the sound and the effect of the midrange offset.
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Re: Something stirs in the Undergrowth

Post by SimonC » Tue Nov 05, 2019 8:51 am

Hi Mark,
Finally got round to grabbing some of the room mode results for you, this is early days as it is just the bare room with no fixtures and furniture. I've got the pretty pictures for all the different modes, but they don't show much apart from it gets complex once you get past the first couple of modes.
Take the results with a pinch of salt, the software might calc to 3 decimal places but there are so many variables and assumptions that go into this that they are all approx values.
Mesh model.png
Mesh model
Modal Freq.png
Modal Freq.png (6.92 KiB) Viewed 387 times
Mode 2.png
Mode 2
Onwards!
Simon C

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Re: Something stirs in the Undergrowth

Post by IslandPink » Tue Nov 05, 2019 8:04 pm

Ah, nice - good work.
I suppose it's not much use putting them up as you need to see them 'in action' ?
Does it require you to drive the sound into the model in a certain place - ie. where the speakers sit ?
I do remember in the bass when testing the tapped horn, from the typical listening position you got 10dB difference with a 5Hz increment.
I'm particularly interested in what happens in the lower midrange of course
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Re: Something stirs in the Undergrowth

Post by SimonC » Wed Nov 06, 2019 10:56 am

IslandPink wrote:
Tue Nov 05, 2019 8:04 pm
Ah, nice - good work.
I suppose it's not much use putting them up as you need to see them 'in action' ?
Does it require you to drive the sound into the model in a certain place - ie. where the speakers sit ?
I do remember in the bass when testing the tapped horn, from the typical listening position you got 10dB difference with a 5Hz increment.
I'm particularly interested in what happens in the lower midrange of course
These are just the frequencies the standing waves in the room will happen at, they don't care what excites them (behave DTB...! I can hear you sniggering at the back from here). My initial interpretation of them is that your room is going to be at its most lively around 60Hz and 75-80Hz as you have a couple of clusters of modes around those regions.
The next step is to add a source into the model (effectively a 'perfect' speaker) and actively drive the room through a range of frequencies to see what happens. Watch this space, but don't hold your breath :)

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Re: Something stirs in the Undergrowth

Post by ed » Wed Nov 06, 2019 11:19 am

Hi Simon

I'm curious as to what can be achieved with this evaluation. I did some very amateur studio measurements back in the day but didn't get very far with nulling bad reflections, other than identifying places to put auralex. Apart from reflections and resonant points what else can be done with modes?

as an aside this can be fun if you fiddle with parameters:

http://kaistale.com/blog/130928roommodes/

edit:
seems I really am out of touch, there is even an app to do the hard work....what will the yoof think of next!
https://www.auralex.com/news-rlx/
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Re: Something stirs in the Undergrowth

Post by SimonC » Wed Nov 06, 2019 4:03 pm

ed wrote:
Wed Nov 06, 2019 11:19 am
Hi Simon
I'm curious as to what can be achieved with this evaluation. I did some very amateur studio measurements back in the day but didn't get very far with nulling bad reflections, other than identifying places to put auralex. Apart from reflections and resonant points what else can be done with modes?
On their own room modes don't really help that much, they can give an idea of which frequencies will excite them which in turn can help explain why a room sounds 'lively' at certain frequencies. It doesn't take into account room treatments or anything else, its just the frequencies that a body of air that size & shape resonates at. Its not easy to change these modal frequencies, you need to do something that changes the physical shape/volume of the body of air. Room treatments are usually something thats trying to absorb energy at certain frequencies, which is something different. In reality its usually the first couple of modes that dominate, the more complex ones tend to be swamped by them (but they do make for pretty animations).

Where I'm going with this is to add in a source (that simulates a speaker) that does a frequency sweep. This lets you look at what these modes do when you give them a shove, and it also lets me start to see the impact of speaker placement and room treatments.

The background is that I use this software (ansys) for work, but for doing structural stress analysis, not acoustics. It has a lot of acoustics functionality, and I'm using this as a project to get myself up the learning curve on the basics of using them. I'm starting very basic ;)

Si

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Re: Something stirs in the Undergrowth

Post by Dave the bass » Wed Nov 06, 2019 8:36 pm

SimonC wrote:
Wed Nov 06, 2019 10:56 am

These are just the frequencies the standing waves in the room will happen at, they don't care what excites them (behave DTB...! I can hear you sniggering at the back from here)..........
I can't help it if you keep posting rude things :)
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Re: Something stirs in the Undergrowth

Post by IslandPink » Sun Nov 10, 2019 8:28 pm

Further fettling has yielded some rewards.
I managed to get some 1mH air-cores with 1mm wire ( 0.4R)
Now I have a slightly lower high-pass on the ribbons , with 3.9uF/1mH into them, About 3kHz I think, the slope is transitional in that it's 1st-order around 3kHz but steepens to 2nd-order lower down. I'm sure it has the name of someone associated with it :)
In conjunction , I had to up the zobel capacitor on the mid drivers a bit to tame the 'crud' I can hear on vocals, so went back from 0.47u to 1.0u ( was 1.5u originally ) .
Overall this seems like a good compromise. I haven't measured it, and I'm sure there's a dip where the two units cross, but I'm happy with it, especially today. Sounds pure and lovely on female vocals.

More on the bass/mid cross later. I have done some pondering and calculating and decided the 85uF I had in the series cross was not nearly enough, despite my previous trials. I have gone up in value and now getting some extra fullness to male vocals, and better timing. Need to listen more but happy so far.
"The bass is the king of the instruments - it has no known natural predator" (Wobble)

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