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Old 27th April 2007, 06:13 PM   #21
v-bro is offline v-bro  Netherlands
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One thing that I'd like to add about the way it was measured is that I measured two speakers in mono mode. I thought this would give a more realistic view because both drivers share eachothers enclosure and normally play in stereo mode. So they influence eachother....

And so the graph can suffer from the comb filtering effects....I couldn't make more measurements as the person who owns the equipment had just little time. That's why I want to get my own measuring set...

Any hints to good software for transient and distortion measurements much appreciated...
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Old 28th April 2007, 08:19 AM   #22
Geoff H is offline Geoff H  Australia
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I might have a solution. Looking at the fr graph:
http://www.bmm-electronics.nl/img/Da...ph-30x-8-d.gif

with the many peaks and dips smoothed out helps see a solution.

What's the input R of the amp? I don't think I can totally null it out, but certainly flatten it, and reduce the 20 dB roll-off above it.

A T filter is like a T-pad or attenuator with reactance included in the legs to make it frequency dependant. A twin-t is two t's in parallel, to create a notch or peak. Many audio oscillators used a twin-t filter in the feedback cct.

Doing some maths, I reckon your dustcap is about 19.5mm across the dome. Though that's probably typical for 3 inchers. 1/2 wl @ 9.6K.

Geoff.

edit: Try the free download of ARTA. I haven't grasped all the features yet, so far so good.
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Old 28th April 2007, 11:10 AM   #23
v-bro is offline v-bro  Netherlands
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Hi, I don't exactly know the input R...10K? I also think the response graph from monacor doesn't comply with reality. The 9.3Khz peak is well visible there though...

The dustcap is 28mm, the voice coil is allready 25mm....

I hear very enthusiastic response about ARTA, will try, thanks.
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Old 28th April 2007, 01:13 PM   #24
Geoff H is offline Geoff H  Australia
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Usually, but not always, the input z is set by the first resistor to ground on the input, or level control. Should be able to measure or see it.

Geoff.
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Old 28th April 2007, 10:50 PM   #25
v-bro is offline v-bro  Netherlands
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Than input Z should be 47K, as the gain setting feedback resistor has that value...

Today I took the portable speaker to a lake nearby (with sandy beaches and islands with bridges). The place attracts a large crowd of people swimming and there are areas where ghettoblasters are alowed Today was very sunny....

There were people quite surprised by the enormous sound from the little 1 liter enclosure with the SPH30X.

I also bought a 27 EUR. similar (but smaller) stereo portable speaker from 'TRUST'. It caught my attention because there's a class D amp inside.

Offcourse my little box has more voltage (double, from 6V to 12V), more liters (triple, 1 liter instead of 0.3), more power* (25 times more 25 watt/ch. instead of 1 watt/ch.) and costs a lot more (about 5 times more, ~150 EUR.).

*and probably a lot more efficient drivers...

But it sounds about 100 times better (it's not like slightly better imaging or differences like inputcap differences, it's the difference beteen 'do you hear anything?' and 'where are the telephone booths with 18 inch drivers and horns?!' (joke, offcourse that's slightly exagerated....).

No really I'm totally surprised by these drivers! (well actually in my book Monacor makes top notch stuff, many brands that produce more exotic drivers for much higher prices don't let you succeed in achieving such soundquality so easy. I LLLLLOOOVE the SP-60 4" driver for instance. 20 years ago I built the first set of speakers with them, back than they cost only ~7 EUR. where they cost ~15 EUR. today (still not expensive). They show excellent specs too! These drivers also allow a pretty powerfull amp to play almost max. on the driver even without enclosure! Phenomenal bass response surprised many people that had a listen to the four (2 per ch.) I use in my car (these four SP60 drivers are really 15 years old! Speaking about durability!) Monacor still sells them, that's what I like, a brand that sticks to what is good! Allmost every driver they make can be used in many applications, they are very very versatile. (so a good investment).

Sure there are probably better drivers, and I didn't try them all. Tangband also caught my eye, but none of the many drivers they make had what I was looking for. Most are designed for indoor use only, or are heavy....I needed:

Low weight (neodyme magnet)
Water and dust resistant (no phase plug...)
High efficiency.
High power handling (especially mechanically)
Shielded magnet.
Small enclosure suitable.
Reasonably low Fs.
Really wide freq. range (for it's size offcourse...)

For sure there are better thinkable applications for it (as mentioned a wooden (MDF...) enclosure for exxample). Didn't try it yet, but probably will. I will buy a lot more of'em for sure!

Another driver I think could be very interesting, the 4" Vifa 10bgs. But I've had many poor results with Vifa drivers in the past (17WP200, D75 and some 10" poly...cone I had were really bad, HT275 was nice though..)

I think the edge is in the edge, the Vifa drivers all had questionable finishing there...the D75 I think had a too heavily coated, too thick material roll edge. The 17WP200 had too tough rubber and the large woofer had a far too wide (therefore unsteady, not linear and lossy) edge in comparison to it's motor power...

SPH30X has a very flexible, but thin, yet durable edge. Seems very low loss and responsible for very detailed response. It also seems to have exactly the right size. The transients it can handle, man I never expected to feel the vibrations in my body from so far away from a 3"! (couple of meters...) I really wish they come up with a 4" version soon. A friend asked me to build a larger and even more powerfull version for him.

I did read many positive responses about the Vifa 10 bgs http://wt.parsimony.net/cgi-bin/view...itragsnummer=2
http://www.speaker-online.de/preise/pico.gif

Anyone with experience please share, I'd especially be interested to know about the mechanical capabilities of this driver? Does it rattle by the voice coil slamming to the poleplate, or does it just end in a bit rougher and distorted sound?

Keep
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Old 29th April 2007, 01:42 AM   #26
Geoff H is offline Geoff H  Australia
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Hi v-bro. Try this. The 47K - 0.001 uF should provide roll off above 6khZ
The 0.82nF provides boost at 14kHz. Max attenuation should be about 7 dB @ 9K.

If that works out OK, we can add BSC.

If you change values to taste, change one at a time, they will interact a little.

Geoff
Attached Images
File Type: gif pleq_sph30x-s.gif (5.2 KB, 1396 views)
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Old 29th April 2007, 06:35 PM   #27
v-bro is offline v-bro  Netherlands
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Hi Geoff, thanks a LOT! Will sure try, maybe tomorrow because I have to get the values...and have too little time right now.

It would also be nice to have ARTA up and running to show the measured differences...
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Old 30th April 2007, 10:39 AM   #28
v-bro is offline v-bro  Netherlands
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I've collected the components, think tomorrow I can start experimenting...

The guy who has the measurement equipment will be there too, so maybe I can show some graphs right away....
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Old 2nd May 2007, 02:23 AM   #29
v-bro is offline v-bro  Netherlands
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No measurements yet, but I tried your circuit Geoff, nice things are happening with the high frequencies. But voices still could be somewhat more in the background. My previous 2.5Khz notchfilter with added 1nF caps parallel to the input resistor. The latter absolutely enhances the highest frequencies.

But Monacor probably measured the driver in a baffle, they also seem to add smoothing on the graphs. The enclosure I use is far from ideal, so that might need a different type of filter (or same filter, but other values...)

Looking at the measurement I took from the unfiltered loudspeaker it would seem that it would just need bass boost....

Or maybe Z isn't 47K afterall...I'll have to get back to it tomorrow...
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Old 27th May 2007, 01:43 PM   #30
Dr_EM is offline Dr_EM  United Kingdom
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That SPH30X driver looks interesting and seems to be available in the UK here (any ideas if this site is ok?):

http://www.soundsec.com/store/en/vie...iew=images#tab

Do you think it would work well in a cyburgs needle type design? How is the power handling, it specs higher than the TB W3-871 but can it use it?
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