+1. Screaming 1960s / '70s, including girl & her attire (very Little House on the Prairie). Does the article mention if a brown coat & soft hat are required protective clothing during construction?
Not that a big woofer with horn loaded mid-tweet is a bad combination in itself.
A decent high efficiency woofer and horn can be surprisingly good. I did a pair for my brother last year, and the result surprised both my brother and myself. The crossover was a rather complicated beast, and was not only second order but included trap filters to notch out lumps, but also impedance correction / zobel to get roll offs neat.
The silicon chip crossover omits all the above. I guess if the etone 1525 is well behaved then they might get away with it, but given they allude to crossover frequencies that are miles apart for low and high pass, I suspect they were struggling to get a flat response.
The thing that disappoints me the most is the hype and rubbish they use in their promotion and article.
The speaker may well be quite decent. But it can never do what they promise. So in their presentation they lose the opportunity to promote the speakers main assets, great efficiency, modest distortion and immense spl capability on a "pretty good" pass and.
A pity
The silicon chip crossover omits all the above. I guess if the etone 1525 is well behaved then they might get away with it, but given they allude to crossover frequencies that are miles apart for low and high pass, I suspect they were struggling to get a flat response.
The thing that disappoints me the most is the hype and rubbish they use in their promotion and article.
The speaker may well be quite decent. But it can never do what they promise. So in their presentation they lose the opportunity to promote the speakers main assets, great efficiency, modest distortion and immense spl capability on a "pretty good" pass and.
A pity
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I suspect they weren't interested. Broadband +/-3 dB as they've done takes the vocal 'shout' out of today's typical CDs 'voiced' for the various mobile audio apps.
A good rule-of-thumb is for the horn to have a mouth area = the LF's [Sd], so the 1525 would indeed have to be very well controlled above ~700 Hz to mate to such a small horn, especially 1st order. From just looking at its picture, it just might be, and combined with its ~Altec 416 specs I can't help but wonder if it's a 'close enough' clone.
Regardless, I've built quite a few wide BW 12" pulled from consoles + small horn with only a 4.7 uF cap with good sounding in-room results, so not as quick to dismiss the design concept as some, though 'best ever published DIY speaker', not even close! The choice of horn alone disqualifies it.
GM
Well, this is an Aussie mag, and we know how humble and classy people they are...
Browse Silicon Chip issues - Silicon Chip Online
Browse Silicon Chip issues - Silicon Chip Online
Well there's the glitter and glamour of Stereophile
I think it's great/different. Looks old/daggy. Pure DIY
Hi,
Everything screams someone in their dotage trying
to relive the days when you talked utter nonsense
about your latest speakers (Bud Fried anyone ?).
Back it up with a load of poor measurements
and talk utter crap for in this case Australia.
97dB and flat to 20Hz is simply not possible.
There is no way a 1st order x/o is good here.
rgds, sreten.
Everything screams someone in their dotage trying
to relive the days when you talked utter nonsense
about your latest speakers (Bud Fried anyone ?).
Back it up with a load of poor measurements
and talk utter crap for in this case Australia.
97dB and flat to 20Hz is simply not possible.
There is no way a 1st order x/o is good here.
rgds, sreten.
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Sure it is, just not at the same time. This is a very common practice when specifying things like frequency response, distortion, output level, etc. for amplifiers and speakers. For instance amplifier company S*** quotes the maximum power that the amplifier can deliver when describing the amp, e.g. a "100W amplifier" and then says "Audiophile distortion levels of <0.1%" or whatever. What they do not say is that the amp produces 10% distortion at 100W, and only if the amp is dialed back to 20W does it have low(er) distortion matching the claimed "audiophile" spec.
The same is done with subwoofers all the time. 117dB output!!! Frequency response to 17Hz! Wow! But when someone actually does a measurement, you see that the driver can only reproduce 17Hz at a much lower SPL level (e.g. <90dB) and that the distortion rises, becoming very bad at the "peak" output, while the low end frequency response is no longer meeting the spec. You just can't get around physics.
It's the omitted details about the measurement conditions (for all specs) that obfuscate the real performance of many audio components. This is why I like to find out what is inside, and then read the manufacturer's datasheet to see what the "best case scenario" looks like. Sometimes it is quite easy to spot the proverbial red herring.
I want to thank you for the thread.
Humor is always nice.
I have no trouble believing the smoothed curve shown. Of course if you move the measurement microphone a bit you will see more of the actual power response curve. The large woofer will have it's pattern narrow as frequency increases. So as it's output drops from the center sweet spot it will give a reasonably flat curve. Same thing with the tweeter. Now to get a really nice graph at the low end just run a clothes washer or some such in the next room while doing the measurements. Just be sure to twiddle the amplifiers volume knob to match the of levels.
There is a difference between a single point frequency response chart and the actual energy vs frequency coming from a loudspeaker
Of course that curve is as flat as the terrain around here. There are three rivers here! My walk to school had an elevation change of 325 feet in a distance of 4500 feet. Going to was easy, the end of the day, not so.
Humor is always nice.
I have no trouble believing the smoothed curve shown. Of course if you move the measurement microphone a bit you will see more of the actual power response curve. The large woofer will have it's pattern narrow as frequency increases. So as it's output drops from the center sweet spot it will give a reasonably flat curve. Same thing with the tweeter. Now to get a really nice graph at the low end just run a clothes washer or some such in the next room while doing the measurements. Just be sure to twiddle the amplifiers volume knob to match the of levels.
There is a difference between a single point frequency response chart and the actual energy vs frequency coming from a loudspeaker
Of course that curve is as flat as the terrain around here. There are three rivers here! My walk to school had an elevation change of 325 feet in a distance of 4500 feet. Going to was easy, the end of the day, not so.
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I subscribed to Silicon Chip mag for years and Ive only just cancelled it a few months ago because of just this type of garbage that they are coming out with.Its been a fairly good mag over the years. The problem is that the editor has gone senile in his old age and I suspect a little nasy,he users the editorial page at the start of the mag every month to rail against anyone and everything however remotely connected to electronics.The magazines front picture tells the story.(A pictures worth a thousand words.Anon.)
Pete Mck
The speakers I built used Beyma G125 bass drivers (12 inch rather than 15 inch) and P.Audio PA-D26 compression drivers on (I don't remember which without going and digging) horns.
Were they "the best DIY speakers ever published anywhere since the start of the universe? ". Hell no. They were made as PA boxes, but by an audiophile who could not stop tweaking the crossover till it was at least "OK".
Did they have a crossover a zillion times more complex than you would want for PA? Yes, absolutely. I could not stop myself from correcting a myriad of flaws in the bass driver and horn. In the process I probably "wasted" a couple of dB of efficiency.
Did they come out with a subjective performance that was broadly in line with a moderate "hifi" speaker. I think so, my brother thought so. Measurements still showed a few peaks and dips that I will refer to as "charachter wobbles". They were not enough to be fatal flaws.
Are they awseomely efficient and able to produce very substantial sound levels? Yep - this is the big selling point of high efficiency drivers.
As most of us know however, there is a trade off to be had. It is a bit like the saying that you can have two of three of: "A fast car, a cheap car and a reliable car".
With speakers you can have two of: "efficient speakers, low frequency extension and small speakers" [I just made that up - it might not quite work.... ]
The speakers I built used Beyma G125 bass drivers (12 inch rather than 15 inch) and P.Audio PA-D26 compression drivers on (I don't remember which without going and digging) horns.
Were they "the best DIY speakers ever published anywhere since the start of the universe? ". Hell no. They were made as PA boxes, but by an audiophile who could not stop tweaking the crossover till it was at least "OK".
Did they have a crossover a zillion times more complex than you would want for PA? Yes, absolutely. I could not stop myself from correcting a myriad of flaws in the bass driver and horn. In the process I probably "wasted" a couple of dB of efficiency.
Did they come out with a subjective performance that was broadly in line with a moderate "hifi" speaker. I think so, my brother thought so. Measurements still showed a few peaks and dips that I will refer to as "charachter wobbles". They were not enough to be fatal flaws
.Are they awseomely efficient and able to produce very substantial sound levels? Yep - this is the big selling point of high efficiency drivers.
As most of us know however, there is a trade off to be had. It is a bit like the saying that you can have two of three of: "A fast car, a cheap car and a reliable car".
With speakers you can have two of: "efficient speakers, low frequency extension and small speakers" [I just made that up - it might not quite work.... ]
People, one thing that has me completely confounded is the incredibly complex porting arrangement.
Can anyone explain why you would port a reflex enclosure using:
-1- A very narrow (a couple of mm, or 1/8 inch or less for th imperial folk) slot, from the main bass reflex enclosure into exiting into
-2- An intermediate "port" which at the top is the few mm wide, and at the bottom slightly wider than a 110mm port (way too small to be a resonant cavity in its own right) and
(much less confounding) -3- with the 110mm port venting into a large flared port at floor level.
The impedance plot indicates that overall they have achieved what appears to be a very low tuning frequency for the driver. This could have been done very simply, I would have used a slot port in a PA box like this.
Is there a reason to use such a constrained porting arrangement? I would expect the air velocities in the initial narrow slot to go completely off the scale at low frequencies.
I have read more on speaker design than most, but this is new to me. Is it aimed at going turbulent at high air flow rates, reducing cone excursion? Ideas???????
Can anyone explain why you would port a reflex enclosure using:
-1- A very narrow (a couple of mm, or 1/8 inch or less for th imperial folk) slot, from the main bass reflex enclosure into exiting into
-2- An intermediate "port" which at the top is the few mm wide, and at the bottom slightly wider than a 110mm port (way too small to be a resonant cavity in its own right) and
(much less confounding) -3- with the 110mm port venting into a large flared port at floor level.
The impedance plot indicates that overall they have achieved what appears to be a very low tuning frequency for the driver. This could have been done very simply, I would have used a slot port in a PA box like this.
Is there a reason to use such a constrained porting arrangement? I would expect the air velocities in the initial narrow slot to go completely off the scale at low frequencies.
I have read more on speaker design than most, but this is new to me. Is it aimed at going turbulent at high air flow rates, reducing cone excursion? Ideas???????
If it wasn't for the QR code on the front, I'd be thinking that was an issue from about 1974...
They paid the stylist an absolute fortune to get that authentic retro look down pat!
I was once a subscriber to Electronics Wold & Wireless World (Now Wireless World). When I had the feeling that it went down the drain I cancelled my subscribtion. I wonder if it has turned to the better again in the meantime ......
I own a few issues of the silicon chip magazine. My opinion is that it is basically a cool mag but that its editor seems to be a know-all, sometimes ranting about subjects he doesn't seem to have the slightest knowledge of....
Regards
Charles
I own a few issues of the silicon chip magazine. My opinion is that it is basically a cool mag but that its editor seems to be a know-all, sometimes ranting about subjects he doesn't seem to have the slightest knowledge of....
Regards
Charles
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