Something stirs in the Undergrowth

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Toppsy
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#2026 Re: Something stirs in the Undergrowth

Post by Toppsy »

IslandPink wrote: Sun Jul 16, 2017 9:51 pm Thanks Colin for link to Monacor drivers on Max's thread -
This one is rather tasty as an OB midrange for Quasar style baffle and crossover - could be worth trying as an alternative to the Supravox 285's , crossover around 150Hz, should give a bit more bass extension ; Qt is 0.40 . Be good to compare against the Eminence Betas. Qm around 13 - should be good at low levels .
http://www.monacor.co.uk/categories/15-3/vnr/103760/

This one more suitable for a flat baffle , rather similar to Eminence Beta in parameters :
http://www.monacor.co.uk/categories/15-3/vnr/101040/
Mark,
for interest cost to me of the above 2 Monacor drivers are:
SPA-115PA (10.3760) - List £129.16. Trade price - £44.59+VAT (£53.50 inc VAT)
TF-1525 (10.1040) - List £84.82. Trade price - £64.69+VAT (£77.63 inc VAT)
Postage would be free on ordering a pair any of the above drivers.

For some strange reason known only to Monacor, the more expensive list priced driver, SPA-115PA, is the cheaper to buy trade. Not too great a savings on the TF-1525?

Regards
Colin
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IslandPink
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#2027 Re: Something stirs in the Undergrowth

Post by IslandPink »

Those are very tempting prices, Colin.
James did point out the suckout at 550/600Hz with the SPA-115PA and associated phase-shifts... but at that price might be worth hearing anyway.
Give me a few days ... :)
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#2028 Re: Something stirs in the Undergrowth

Post by andrew Ivimey »

Tempting! Not aff. Amazing!
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#2029 Re: Something stirs in the Undergrowth

Post by IslandPink »

Well the small array is in action and first impressions are that this is the way to go for an affordable OB midrange. Currently I've just been running it full range on a existing wooden test baffle, with CD and vinyl source. Performance on male vocals and cello is superb. I have an FX120 on loan at the moment sat on a 30L sealed box, and I will have to do some careful comparisons to establish which is best in which application. The FX120 single driver sounds best higher up the frequency range, but this might just be a side-effect of the 2x2 array used on the smaller drivers. Maybe if you want to uses the small array higher-up the freq range it might be better to go for a more conventional 4x1 vertical array which would have less horizontal HF lobing.
As done here it should be about 93db/w with around 20W power handling per channel. Nice combination - and the drivers have very low Rms so they work nicely at low level. The 7kHz peak of the FF105wk is less apparent than when it's used alone - however I think the best combo for this would be a low-pass in the amp somewhere around 3 to 5kHz and a ribbon eg. smaller Fountek coming in 1st-order from a second amp to add more tone in female vocals and sparkle at the top.
Just been looking on EBay and the FE103e/n seem rather scarce - maybe being discontinued ?
Array_baffle1.JPG
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#2030 Re: Something stirs in the Undergrowth

Post by IslandPink »

Meanwhile I think I may have found the ultimate track for testing bass :
( course I knew about this, let's say 'rediscovered' ! )


Three types of bass under the macroscope -
Bass_trio.JPG
..which one will win ?
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chris661
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#2031 Re: Something stirs in the Undergrowth

Post by chris661 »

The brass intro bit only goes down to 65Hz, Mark, and is about 40dB down by 1kHz.
I'd bet whichever is smoother over that region would be the best. Not likely to be the tapped horn since at most you can get about 2 octaves out of them.

I actually find Bjork's It's Oh So Quiet to be a good bass test - try following the double bass through the loud bits. Does it keep its tone while the drivers are doing other things?

Chris
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#2032 Re: Something stirs in the Undergrowth

Post by IslandPink »

The track is nearly 15mins long, was the Youtube just a short bit ?
65 sounds a bit high, it sounds like at least 50Hz at times, although not really low. It's the staccato nature of the (synth) bass that's really good for testing, it really showed up the differences on the three speakers.
Thanks for the tip on Bjork. I will be trying a chip amp and CD source tonight, all being well, and I don't have Koyaanisqatsi on CD.

Bad luck on the quiz Chris - the tapped horn was best. Bear in mind I was specifically concentrating on the bass - and had to shut out the relatively poor midrange from the tapped horn, compared to the other two. The tapped horn is more efficient and the notes were better defined and stopped & started quicker.

Course the tapped horn being best is a headache, as it is harder to integrate - seeing as it only goes up to 150Hz with any quality. Damn !
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#2033 Re: Something stirs in the Undergrowth

Post by chris661 »

I was referring to the intro bit that sounds like some large brass instruments. Do you mean the bit around 7.30?
That goes down to 45Hz-ish, and is 20dB down at 20Hz. Synth bass is difficult, though, because nobody has any idea what it ought to sound like - by definition it's an arbitrary waveform. I do take your point about it stopping and starting, though.

For bass alone, I can see the tapped horn doing quite well, but as you've noted, integrating them is a real difficulty. IME, DSP is pretty much mandatory there - the out-of-band peaks as well as the time alignment issues mean doing it in the analogue domain would require a lot of circuitry.

You can improve things by adding Helmholtz resonators that are tuned to absorb particular harmonics of the line length. Danley does that sort of thing and they get good results at the top end of their cabinets. Implementing such things would be non-trivial, though, and would need simulating in Akabak. Hornresp won't come close.

Chris
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#2034 Re: Something stirs in the Undergrowth

Post by IslandPink »

chris661 wrote: Tue Jul 25, 2017 3:06 pm Do you mean the bit around 7.30?
Probably ... but just checking now, all of that low bass is inaudible on my PC speakers ! :D
Agreed, DSP could be useful for getting the best out of these - especially as tapped horns are not happy with passive components eg. chokes at the speaker end. Nick and I did get a decent blend of the folded horn with this horn using MiniDSP a few months ago, with a 70Hz crossover.

I was perhaps being pessimistic when I said 150Hz max - from early tests I reckon the tones were pleasant enough up to 200Hz but getting distorted by 250Hz. With the FX120's on this OB which is more or less like an IEC baffle ie. as per datasheet, they're shown as 1dB down at 150Hz and about 4dB at 100Hz. It's a bit tighter than I'd like to get the 'mush' above 200Hz out of the way. FIR would be handy - Nick's on the case .
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#2035 Re: Something stirs in the Undergrowth

Post by IslandPink »

Plot thickens ... playing from CD & chip amp tonight and results between Quasar and Tapped horn are closer. In particular tapped horn seems less good. Was looking at sims though too ... amplitude was optimised at time of design, to be dead flat from 40Hz to 150Hz -but with 0.2 ohm driving impedance. Thought, if it sounded better from vinyl last night - 1.5 or 2R Zout - then maybe phase was an issue. Checked Hornresp and as series resistance is raised by an ohm or two, group delay at 40Hz improves from >25msec to less than 20msec. Put in a 3R3 resistor at speaker ( bit too much ) and it sounds better. Another example of phase being more important than amplitude. However - doesn't explain why it's better than 285GMF on Quasar ( at least from vinyl ) as that has loads better group delay. I can feel madness coming on, so better stop & relax .
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#2036 Re: Something stirs in the Undergrowth

Post by chris661 »

The phase response on the Quasar might be better, but if there are larger amplitude variations, that will factor in - if something has a 10dB dip but has a flat phase response, but something else is flat in amplitude but has some phase wiggles, choosing between them gets more difficult. Neither should be discounted completely IMO.

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#2037 Re: Something stirs in the Undergrowth

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By the time I went to bed I was thinking the best approach would be to build the Quasar style mid/lows and then add in some output from the tapped horn separately using DSP - and just for a small band from 35Hz up to about 60 or 70 - use it like a sub.
Also I was thinking sadly that most solutions don't get that close to the real life bass sound - and going back to Paul's comments about the Edgar Seismic ( or is it Monolith ? ) sub, which is probably the closest thing to a PROPER (HiFI) bass system !

So this weekend I will get a second FX120 to play with, so I wil get the two mounted up and attempt to get a series cross for the 285GMF + 2xFX120 - should be very much like the original AER/285 crossover values. The key is can it work with the -3dB @ 700Hz cross from the amp. With the cross erroneously at -6dB @ 700Hz , before, it didn't work, because the bass/mids 'came apart' in the process, but I think I might be able to manage it with the re-thunk 700Hz filter.
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#2038 Re: Something stirs in the Undergrowth

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Hadn't seen this page - great stuff :
http://www.klipsch.com/founder
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#2039 Re: Something stirs in the Undergrowth

Post by IslandPink »

More experiments this weekend and generally progress ... apart from dropping a heavy test baffle on my foot ( with sandals ) . Thankfully not as bad as the Barker/slate plinth incident a few years ago.
Got router and jigsaw etc out again, and made -
(I) small panel from 12mm birch for 2xFX120 drivers
(ii) hacked ( sadly ) into one Perspex baffle to enlarge the upper hole to take either the 2x2 array or the FX120 array
So , the scene at present looks like this :
Array_FX120.JPG
The only fly in the ointment is that the FX120 when played on the box ( on stool ) to the left has recalibrated my aims for the lower midrange and upper bass :roll:

So, but anyway - the pair of FX120's are a superb substitute for the AER Mk.1 if you want a Quasar combination. They are the best of the four (?) options I've tried over the last few years . With this as a stand-alone set-up, the cap value for a series crossover with 8.2mH air-cored choke appears to be somewhere between 130uF and 165uF. I will try & pin it down tighter eventually.

Now, if you ditch the Quasar crossover and listen to the Yuichi horn and the FX120 pair only, they also blend very nicely and deliver a fair amount of lower mids and upper bass with very tight timing and snap ( & tone ).

Course when you try & get the whole lot together, with the 700Hz amp low-pass on the mid/bass Quasar combo, the lower mids & upper bass still start to lose coherence to some extent. Enough that when compared to a single FX120 on a 30L box ( damn you ) you find it disappointing. The combination is better with -3dB @ 700Hz than it was with -6dB @ 700Hz, though :oops:
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andrew Ivimey
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#2040 Re: Something stirs in the Undergrowth

Post by andrew Ivimey »

It's just dawned on me that this post isn't going to end is it! However for some reason this posting feels better, progress-wise, than many.

Onwards!
Philosophers have only interpreted the world - the point, however, is to change it. No it isn't ... maybe we should leave it alone for a while.
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